Information
-
Patent Grant
-
6644059
-
Patent Number
6,644,059
-
Date Filed
Wednesday, November 20, 200221 years ago
-
Date Issued
Tuesday, November 11, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Doerrler; William C.
- Shulman; Mark S.
Agents
- Armstrong, Westerman & Hattori, LLP.
-
CPC
-
US Classifications
Field of Search
US
- 062 271
- 062 94
- 062 2383
- 062 92
- 062 3241
-
International Classifications
-
Abstract
A dehumidifying apparatus capable of continuously supplying dry air having an absolute humidity of 4 g/kgDA or lower is provided. The dehumidifying apparatus has a moisture adsorbing device for removing moisture from process air and for being regenerated by desorbing moisture therefrom with regeneration air B, and a heat pump having a condenser for condensing a refrigerant to heat the regeneration air at the upstream side of the moisture adsorbing device, an evaporator for evaporating the refrigerant to cool the regeneration air to a temperature equal to or lower than its dew point at the downstream side of the moisture adsorbing device, a pressurizer for raising a pressure of the refrigerant evaporated by the evaporator and delivering the refrigerant to the condenser, and a heat exchanger for exchanging heat between the regeneration air flowing between the moisture adsorbing device and the evaporator and the regeneration air flowing between the evaporator and the condenser, wherein said regeneration air is used in circulation. Since moisture is removed from the process air by the moisture adsorbing device, it is possible to obtain air having a low dew point equal to or lower than an freezing point, i.e., a low absolute humidity of 4 g/kgDA or lower.
Description
TECHNICAL FIELD
The present invention relates to a dehumidifying apparatus, and more particularly to a dehumidifying apparatus having a high moisture removal.
BACKGROUND ART
As shown in
FIG. 17
, there has heretofore been available a dehumidifying apparatus
11
having a compressor
1
for compressing a refrigerant C, a condenser
2
for condensing the compressed refrigerant C to heat process air A, an evaporator
3
for depressurizing the condensed refrigerant C with an expansion valve
5
and evaporating the refrigerant to cool the process air A to a temperature equal to or lower than its dew point. The evaporator
3
cools the process air A from an air-conditioned space
10
to a temperature equal to or lower than its dew point to remove moisture from the process air A, the condenser
2
heats the process air A which has been cooled to a temperature equal to or lower than its dew point, and the heated process air A is supplied to the air-conditioned space
10
. With the illustrated dehumidifying apparatus
11
, a heat pump HP is constituted by the compressor
1
, the condenser
2
, the expansion valve
5
, and the evaporator
3
. The heat pump HP pumps heat from the process air A which flows through the evaporator
3
into the process air A which flows through the condenser
2
.
The conventional dehumidifying apparatus
11
having the heat pump HP cannot supply dry air having an absolute humidity of 4 g/kgDA or lower. The reason is that since the operating temperature of the evaporator
3
in the heat pump HP is equal to or lower than the freezing point, the removed moisture is deposited as frost on the heat transfer surface to inhibit the heat transfer, and hence the apparatus cannot continuously be operated.
It is therefore an object of the present invention to provide a dehumidifying apparatus which can prevent moisture removed from air from being deposited as frost on a heat transfer surface of an evaporator in a heat pump to continuously supply dry air having an absolute humidity of 4 g/kgDA or lower.
DISCLOSURE OF INVENTION
To achieve the above object, according to an aspect of the present invention, as shown in
FIG. 1
, for example, there is provided a dehumidifying apparatus comprising: a moisture adsorbing device
103
for removing moisture from process air A and for being regenerated by desorbing moisture therefrom with regeneration air B; and a heat pump HP
1
having a condenser
220
for condensing a refrigerant C to heat said regeneration air B at the upstream side of said moisture adsorbing device
103
, an evaporator
210
for evaporating said refrigerant C to cool said regeneration air B to a temperature equal to or lower than its dew point at the downstream side of said moisture adsorbing device
103
, a pressurizer
260
for raising a pressure of said refrigerant C evaporated by said evaporator
210
and delivering said refrigerant C to said condenser
220
, and a first heat exchanger
300
for exchanging heat between said regeneration air B flowing between said moisture adsorbing device
103
and said evaporator
210
and the regeneration air B flowing between said evaporator
210
and said condenser
220
; wherein said regeneration air B is used in circulation.
With the above arrangement, since the dehumidifying apparatus has the condenser, the evaporator, and the first heat exchanger, the regeneration air is circulated such that it is heated by the condenser, regenerates the moisture adsorbing device to increase the amount of moisture contained in the regeneration air, is cooled by the first heat exchanger, is cooled and condensed by the evaporator to reduce the amount of moisture contained in the regeneration air, and is heated by the first heat exchanger. When the regeneration air is cooled by the first heat exchanger, the moisture thereof may partly be condensed, reducing the amount of moisture contained in the regeneration air. The regeneration air is cooled (precooled) by the first heat exchanger prior to cooling in the evaporator, and is heated (preheated) by the heat exchanger after cooling by the evaporator. Therefore, the dehumidifying apparatus can be operated at a low sensible heat factor.
Since the moisture of the process air is adsorbed by the moisture adsorbing device, the humidity of the process air is greatly reduced, and hence dry air can be supplied. The expression that the regeneration air is used in circulation means that after having regenerated the moisture adsorbing device, e.g., the desiccant of a desiccant wheel, the regeneration air flows a circulating circuit so that most of the regeneration air can be used again as regeneration air, without being discharged directly into the atmosphere (no regeneration air may be discharged into the atmosphere, or part of regeneration air may be discharged into the atmosphere).
In the first heat exchanger, the refrigerant is evaporated and condensed typically under an intermediate pressure between the condensing pressure in the condenser and the evaporating pressure in the evaporator.
In the dehumidifying apparatus, the first heat exchanger
300
may comprise a thin pipe group connecting the condenser
220
and the evaporator
210
to each other, for passing the refrigerant therethrough; wherein the thin pipe group may be arranged so as to introduce the refrigerant condensed by the condenser
220
to the evaporator
210
and also to bring said refrigerant into alternate contact with the regeneration air flowing between the moisture adsorbing device
103
and the evaporator
210
and the regeneration air flowing between the evaporator
210
and the condenser
220
.
With the above arrangement, since the thin pipe group into which the refrigerant is introduced is brought into alternate contact with the regeneration air flowing between the moisture adsorbing device and the evaporator and the regeneration air flowing between the evaporator and the condenser, heat exchange between these two flows of the regeneration air can be performed by the refrigerant. The connection between the condenser and the evaporator includes indirectly connecting the condenser and the evaporator with a pipe, a pipe joint, or the like.
In the dehumidifying apparatus, as shown in
FIG. 1
, for example, the first heat exchanger
300
may have a first compartment
310
for passing the regeneration air between the moisture adsorbing device
103
and the evaporator
210
, and a second compartment
320
for passing the regeneration air between the evaporator
210
and the condenser
220
, the thin pipe group being connected to the condenser
220
through a first restriction
330
, extending alternately through the first compartment
310
and the second compartment
320
repeatedly, and then being connected to the evaporator
210
through a second restriction
250
.
With the above arrangement, since the dehumidifying apparatus has the first restriction and the second restriction, while the refrigerant is passing through the first restriction and the second restriction, the refrigerant develops a pressure drop across each of the first restriction and the second restriction. The refrigerant passing through the first compartment is evaporated and the refrigerant passing through the second compartment is condensed under an intermediate pressure between the condensing pressure of the refrigerant in the condenser and the evaporating pressure of the refrigerant in the evaporator. Therefore, the heat exchanger acts as an economizer, and the coefficient of performance (COP) of the heat pump is increased.
As shown in
FIG. 13
, for example, the dehumidifying apparatus may have a plurality of thin pipe groups
51
(
52
,
53
) connected to the condenser
220
through first restrictions
331
a
(
332
a,
333
a
) and alternatively extending through the first compartment
310
and the second compartment
320
repeatedly and then connected to the evaporator
210
through corresponding second restrictions
331
b
(
332
b,
333
b
), and a plurality of combinations of the first restrictions
331
a,
332
a,
333
a
and the second restrictions
331
b,
332
b,
333
b
which correspond respectively tothe thin pipe groups
51
,
52
,
53
. As shown in
FIG. 13
, the first compartment
310
and the second compartment
320
should preferably be arranged such that the regeneration air flows as counterflows in the respective compartments
310
,
320
.
In the dehumidifying apparatus, as shown in
FIG. 8
, for example, the first compartment
310
and the second compartment
320
may be arranged such that the regeneration air flows as counterflows in the respective compartments
310
,
320
; and the thin pipe groups in the first compartment
310
and the second compartment
320
may have at least a pair of a first compartment extending portion
251
B and a second compartment extending portion
252
B in a first plane PB which is substantially perpendicular to the flows of the regeneration air, at least a pair of a first compartment extending portion
251
C and a second compartment extending portions
252
C in a second plane PC, different from the first plane PB, which is substantially perpendicular to the flows of the regeneration air, and an intermediate restriction
331
disposed in a transitional location from the first plane PB to the second plane PC.
With the above arrangement, from the viewpoint of heat exchange between the flows of the regeneration air, a high heat exchange efficiency is achieved because heat exchange can be performed between counterflows. The thin pipe groups have at least a pair of a first compartment extending portion and a second compartment extending portion in the first plane to form a pair of refrigerant paths, and at least a pair of a first compartment extending portion and a second compartment extending portion in the second plane, different from the first plane, which is substantially perpendicular to the flows of the regeneration air, to form a pair of refrigerant paths. Therefore, the heat exchanger can be constructed in a small compact size as a whole. Since the thin pipe groups also have an intermediate restriction disposed in a transitional location from the first plane to the second plane, the pressure of evaporation or condensation in the first and second compartment extending portions in the second plane can be of a value lower than the pressure of evaporation or condensation in the first and second compartment extending portions in the first plane. Accordingly, the heat exchange between the flows of the regeneration air flowing through the respective compartments can be made similar to counterflow heat exchange, thus increasing the heat exchange efficiency. The first plane and the second plane typically comprise rectangular planes.
As shown in
FIG. 1
, for example, the dehumidifying apparatus may have a second heat exchanger
340
disposed in the passage of the regeneration air used in circulation, for exchanging heat between the regeneration air and another fluid.
With the above arrangement, the second heat exchanger is capable of exchanging heat between the regeneration air and the other fluid for cooling or heating the regeneration air. The second heat exchanger typically cools the regeneration air.
As shown in
FIG. 6
, for example, the second heat exchanger
340
a
comprises a second thin pipe group connecting the condenser
220
and the first heat exchanger
300
to each other, for passing the refrigerant therethrough, and the second thin pipe group is arranged so as to introduce the refrigerant condensed by the condenser
220
to the first heat exchanger
300
and also to bring the refrigerant into alternate contact with the regeneration air flowing between the moisture adsorbing device
103
and the first heat exchanger
300
and the other fluid.
With the above arrangement, the second heat exchanger is capable of exchanging heat between the regeneration air and the other fluid via the refrigerant.
The other fluid should preferably comprise external air. With this arrangement, the excessive amount of heat of the regeneration air can be discharged into external air which is an almost unlimited source of heat.
The present application is based on Japanese patent application No. 2000-025811 filed on Feb. 3, 2000, which is incorporated herein as part of the disclosure of the present application.
The present invention can more fully be understood based on the following detailed description. Further applications of the present invention will become more apparent from the following detailed description. However, the following detailed description and specific examples will be described as preferred embodiments only for the purpose of explaining the present invention. It is evident to a person skilled in the art that various changes and modifications can be made to the embodiments in the following detailed description within the spirit and scope of the present invention.
The applicant has no intention to dedicate any of the embodiments described below to the public, and any of the disclosed modifications and alternatives which may not be included in the scope of the claims constitutes part of the invention under the doctrine of equivalent.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1
is a flow diagram of a dehumidifying apparatus according to a first embodiment of the present invention;
FIG. 2
is a cross-sectional front view schematically showing a structure of the dehumidifying apparatus shown in
FIG. 1
;
FIG. 3
is a Mollier diagram of a heat pump of the dehumidifying apparatus shown in
FIG. 1
;
FIG. 4
is a psychrometric chart illustrative of operation of the dehumidifying apparatus shown in
FIG. 1
;
FIG. 5
is a schematic cross-sectional view illustrative of a behavior of a refrigerant in a first heat exchanger and a second heat exchanger used in the first embodiment of the present invention;
FIG. 6
is a flow diagram of a dehumidifying apparatus according to a second embodiment of the present invention;
FIG. 7
is a Mollier diagram of a heat pump of the dehumidifying apparatus shown in
FIG. 6
;
FIG. 8
is a flow diagram of major components of a dehumidifying apparatus according to a third embodiment of the present invention;
FIG. 9
is a Mollier diagram of a heat pump of the dehumidifying apparatus shown in
FIG. 8
;
FIG. 10
is a flow diagram of a heat exchanger of a dehumidifying apparatus according to a fourth embodiment of the present invention;
FIG. 11
is a Mollier diagram of a heat pump of the dehumidifying apparatus shown in
FIG. 10
;
FIGS.
12
(
a
) and
12
(
b
) are cross-sectional plan and side elevational views, respectively, of a heat exchanger suitable for use in the heat pump of the dehumidifying apparatus according to the embodiment of the present invention;
FIG. 13
is a flow diagram of a heat exchanger of a dehumidifying apparatus according to a fifth embodiment of the present invention;
FIG. 14
is a Mollier diagram of a heat pump of the dehumidifying apparatus shown in
FIG. 13
;
FIG. 15
is an enlarged plan view schematically showing a heat exchanger shown in
FIG. 13
;
FIG. 16
is a perspective view, partly cut away, showing a structure of a typical desiccant wheel for use in the dehumidifying apparatus according to the embodiment of the present invention; and
FIG. 17
is a flow diagram of a conventional dehumidifying air-conditioning apparatus.
DESCRIPTION OF THE REFERENCE NUMERALS AND SIGNS
21
,
22
,
23
dehumidifying apparatus
101
air-conditioned space
103
desiccant wheel
102
,
140
air blower
210
evaporator
220
condenser
251
,
251
A,
251
B,
251
C,
251
D,
251
E evaporating section
252
,
252
A,
252
B,
252
C,
252
D,
252
E condensing section
250
restriction
260
compressor
300
,
300
b,
300
c,
300
d,
300
e
heat exchanger
310
first compartment
320
second compartment
330
restriction
331
,
332
intermediate restriction
340
,
340
a
heat exchanger
HP
1
, HP
2
, HP
3
, HP
4
heat pump
PA, PB, PC, PD, PE plane
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. Identical or corresponding parts are denoted by identical or like reference characters throughout drawings, and will not be described repetitively.
FIG. 1
is a flow diagram of a dehumidifying apparatus
21
according to a first embodiment of the present invention. The dehumidifying apparatus
21
circulates regeneration air B to regenerate a desiccant and dehumidifies process air A with use of the desiccant.
FIG. 2
is a cross-sectional front view of the dehumidifying apparatus
21
shown in FIG.
1
.
FIG. 3
is a refrigerant Mollier diagram of a heat pump HP
1
included in the dehumidifying apparatus
21
shown in
FIG. 1
, and
FIG. 4
is a psychrometric chart of the dehumidifying apparatus
21
shown in FIG.
1
.
Structural details of the dehumidifying apparatus
21
according to the first embodiment will be described below with reference to FIG.
1
. The dehumidifying apparatus
21
cools the regeneration air B which has regenerated the desiccant to a temperature equal to or lower than its dew point to condense the moisture in the regeneration air B into water and collect the condensed water, and dehumidifies the process air A with the regenerated desiccant to keep an air-conditioned space
101
which is supplied with the process air A at a low humidity level.
In
FIG. 1
, devices related to the process air will be described along a path for the process air A from the air-conditioned space
101
. A path
107
connected to the air-conditioned space
101
, an air blower
102
for circulating the process air A, a path
108
, a desiccant wheel
103
filled with a desiccant for adsorbing the moisture of the process air A that passes therethrough to lower the humidity of the process air A, and a path
109
are arranged in the order named so as to return the process air A from the path
109
to the air-conditioned space. The paths
107
through
109
connect the devices mentioned before the respective paths
107
through
109
to the devices mentioned after the respective paths
107
through
109
. The desiccant wheel
103
serves as a moisture adsorbing device according to the present invention.
Devices related to the regeneration air will be described below along a path of the regeneration air B.
A second compartment
320
of a heat exchanger
300
serving as an economizer of the heat pump HP
1
, a path
124
, a condenser
220
, a path
125
, the desiccant wheel
103
filled with the desiccant which is regenerated by the regeneration air B passing therethrough, a path
126
a,
a second heat exchanger
340
for exchanging heat between external air as another fluid and the regeneration air B, a path
126
b,
a first compartment
310
of a first heat exchanger
300
, a path
127
, an air blower
140
for circulating the regeneration air B, a path
128
, an evaporator
210
for cooling the regeneration air B to a temperature equal to or lower than its dew point to condense the moisture in the regeneration air B into water and collect the condensed water, and a path
129
are arranged in the order named so as to return the regeneration air B from the path
129
to the second compartment
320
of the heat exchanger
300
and to circulate the regeneration air B. Since the regeneration air B is not required to be discharged out of the circulating system and highly humid air is not discharged into an indoor space (air-conditioned space
101
), the dehumidifying apparatus
21
is not limited to any installation area and may be mobile.
The paths
124
through
129
connect the devices mentioned before the respective paths
124
through
129
to the devices mentioned after the respective paths
124
through
129
. The moisture in the regeneration air B which has been condensed by the evaporator
210
is collected by a drain pan
451
disposed vertically below the evaporator
210
, and then accumulated in a drain tank
450
.
Devices of the heat pump HP
1
for moving (pumping) heat with use of a refrigerant C will be described below along the path of the refrigerant C.
An evaporator
210
for heating the refrigerant C with the regeneration air to evaporate the refrigerant C, a path
201
, a compressor
260
serving as a pressurizer according to the present invention for compressing the refrigerant C that has been evaporated into a vapor by the evaporator
210
, a path
202
, a condenser
220
for cooling the refrigerant C with the regeneration air to condense the refrigerant C, a path
203
having a restriction
330
disposed thereon, a condensing section
252
for heating the regeneration air B which flows through the second compartment
320
of the first heat exchanger
300
, an evaporating section
251
for cooling the regeneration air B which flows through the first compartment
310
of the first heat exchanger
300
, and a path
204
having a restriction
250
disposed thereon are arranged in the order named so as to return the refrigerant C to the evaporator
210
. The paths
201
through
204
connect the devices mentioned before the respective paths
201
through
204
to the devices mentioned after the respective paths
201
through
204
.
The desiccant wheel
130
will be described later in detail with reference to FIG.
16
.
Next, referring to
FIG. 1
, structural details of the heat exchanger
300
will be described below. The heat exchanger
300
comprises a heat exchanger for performing heat exchange between the regeneration air B flowing into the evaporator
210
and the regeneration air B flowing out of the evaporator
210
, indirectly with the refrigerant C. The heat exchanger
300
has a plurality of substantially parallel heat exchange tubes as refrigerant paths or tubules in each of a plurality of different planes PA, PB, PC, PD which lie perpendicularly to the sheet of FIG.
1
and also to the flow of the regeneration air B (four planes are illustrated in
FIG. 1
, but the number of planes is not limited thereto). In
FIG. 1
, only one tube is shown in each of the above planes for simple illustration.
The heat exchanger
300
has the first compartment
310
for allowing the regeneration air B before flowing through the evaporator
210
to pass therethrough, and the second compartment
320
for allowing the regeneration air B after flowing through the evaporator
210
to pass therethrough. The first compartment
310
and the second compartment
320
form respective separate spaces, each in the form of a rectangular parallelepiped. Both of the compartments have partition walls
301
,
302
disposed adjacent to each other, respectively, and the heat exchange tubes extend through these two partition walls
301
,
302
.
In an other embodiment, the he at exchanger
300
may be constructed such that a single space in the form of a rectangular parallelepiped is divided by a single partition wall and the heat exchange tubes as a group of thin pipes extend through the partition wall and alternatively through the first compartment and the second compartment (see
FIGS. 5
,
12
(
a
) and
12
(
b
)).
The regeneration air B which has flowed from the desiccant wheel
103
passes from the right in FIG.
1
through the path
126
a
into the heat exchanger
340
, is precooled in the heat exchanger
340
, is supplied through the path
126
b
into the first compartment
310
of the heat exchanger
300
, and then flows out of the heat exchanger
300
from the left in FIG.
1
through the path
127
. On the other hand, the regeneration air B which has passed through the evaporator
210
and has been cooled to a temperature equal to or lower than its dew point with the lowered absolute humidity is supplied from the left in FIG.
1
through the path
129
into the second compartment
320
of the heat exchanger
300
, and then flows out of the heat exchanger
300
from the right side of the second compartment
320
of the heat exchanger
300
through the path
124
.
As shown in
FIG. 1
, the above heat exchange tubes extend through the first compartment
310
, the second compartment
320
, and the partition walls
301
,
302
which separate those compartments from each other. The heat exchange tubes disposed in the plane PA, for example, have portions extending through the first compartment
310
, and such portions are referred to as an evaporating section
251
A (hereinafter simply referred to as an evaporating section
251
in the case where it is not necessary to discuss a plurality of evaporating sections separately). The heat exchange tubes disposed in the plane PA also have portions extending through the second compartment
320
, and such portions are referred to as a condensing section
252
A (hereinafter simply referred to as a condensing section
252
in the case where it is not necessary to discuss a plurality of condensing sections separately). The evaporating section
251
A and the condensing section
252
A serve as a pair of first and second compartment extending portions, and constitute refrigerant paths.
Further, the heat exchange tubes disposed in the plane PB have portions extending through the first compartment
310
, and such portions are referred to as an evaporating section
251
B. The heat exchange tubes disposed in the plane PB also have portions extending through the second compartment
320
, and such portions, which constitute a pair of refrigerant paths with the evaporating section
251
B, are referred to as a condensing section
252
B. Refrigerant paths are also provided in each of the planes PC, . . . as with the plane PB.
As shown in
FIG. 1
, the evaporating section
251
A and the condensing section
252
A are paired with each other and formed by a single tube as an integral passage. This feature, together with the fact that the first compartment
310
and the second compartment
320
are positioned adjacent to each other with the two partition walls
301
,
302
being interposed therebetween, is effective in making the heat exchanger
300
small and compact as a whole.
In the heat exchanger shown in
FIG. 1
according to the present embodiment, the evaporating sections
251
A,
251
B,
251
C, . . . as the first compartment extending portions are successively arranged in the order named from the right in
FIG. 1
, and the condensing sections
252
A,
252
B,
252
C, . . . the second compartment extending portions are also successively arranged in the order named from the right in FIG.
1
.
Further, as shown in
FIG. 1
, the end of the evaporating section
251
A (remote from the partition wall
301
) and the end of the evaporating section
251
B (remote from the partition wall
301
) are connected to each other by a U tube. The end of the condensing section
252
B and the end of the condensing section
252
C are similarly connected to each other by a U tube.
Therefore, the refrigerant C flowing in one direction from the condensing section
252
A through the evaporating section
251
A is introduced into the evaporating section
251
B via the U tube, and then flows into the condensing section
252
B, from which the refrigerant flows into the condensing section
252
C via the U tube. In this manner, the refrigerant paths including the evaporating sections and the condensing sections extend alternately repetitively through the first compartment
310
and the second compartment
320
. In other words, the refrigerant paths are provided as a group of meandering thin pipes. A group of meandering thin pipes pass through the first compartment
310
and the second compartment
320
, and are held in alternate contact with the regeneration air B which has a higher temperature and the regeneration air B which has a lower temperature.
While the refrigerant from the restriction
330
is first introduced into the condensing section
252
A in the present embodiment, the refrigerant may first be introduced into the evaporating section
251
A. According to such a modification, the end of the condensing section
252
A (remote from the partition wall
302
) and the end of the condensing section
252
B (remote from the partition wall
302
) are connected to each other by a U tube, and the end of the evaporating section
251
B and the end of the evaporating section
251
C are similarly connected to each other by a U tube.
Next, flows of the refrigerant C between the devices will be described below with reference to FIG.
1
.
In
FIG. 1
, a refrigerant vapor C compressed by the refrigerant compressor
260
is introduced into the refrigerant condenser
220
via the refrigerant vapor pipe
202
connected to the discharge port of the compressor
260
. The refrigerant vapor C compressed by the compressor
260
is cooled and condensed by the regeneration air B as cooling air immediately before flowing into the desiccant wheel
103
, to thus heat the regeneration air B.
The condenser
220
has a refrigerant outlet connected by the refrigerant passage
203
to the inlet of the condensing section
252
A in the heat exchanger
300
. The restriction
330
is disposed on the refrigerant path
203
near the inlet of the condensing section
252
A.
The refrigerant liquid C that flows out of the condenser
220
is depressurized by the restriction
330
and expanded so as to be partly evaporated (flashed). The refrigerant C which is a mixture of the liquid and the vapor reaches the condensing section
252
A, where the refrigerant liquid C flows so as to wet the inner wall surface of the tube in the condensing section
252
A. The flushed refrigerant is cooled and condensed by the cooled regeneration air B immediately after it has flowed out of the evaporator
210
. When the refrigerant is thus condensed, the regeneration air B flowing through the second compartment
320
, i.e., the regeneration air B which has been cooled and dehumidified by the evaporator
210
to a temperature lower than the temperature of the regeneration air before flowing into the evaporator
210
, is heated (preheated).
The condensing section
252
A and the evaporating section
251
A are constructed as a continuous tube. Specifically, since the condensing section
252
A and the evaporating section
251
A are provided as an integral passage, the condensed refrigerant liquid C (and the refrigerant liquid C which has not been condensed) flows into the evaporating section
251
A. The refrigerant C is then heated and evaporated by the regeneration air B which has flowed out of the desiccant wheel
103
and has been cooled to a certain extent in the heat exchanger
340
, thus further cooling (precooling) the regeneration air B flowing through the first compartment
310
. This regeneration air B is the regeneration air B before flowing into the evaporator
210
.
As described above, the heat exchanger
300
has the evaporating section as the refrigerant path extending through the first compartment
310
and the condensing section as the refrigerant path extending through the second compartment
320
(at least one pair of them, e.g., denoted by
251
A and
252
A) in the first plane PA, and also has the condensing section as the refrigerant path extending through the second compartment
320
and the evaporating section as the refrigerant path extending through the first compartment
310
(at least one pair of them, e.g., denoted by
252
B and
251
B) in the second plane PB.
The outlet of the final condensing section
252
D in the heat exchanger
300
is connected to the evaporator
210
via the refrigerant liquid pipe
204
, and the expansion valve
250
is disposed as a restriction on the refrigerant pipe
204
.
The refrigerant liquid C condensed in the condensing section
252
is depressurized and expanded by the restriction
250
to lower its temperature. Then, the refrigerant liquid enters the refrigerant evaporator
210
and is evaporated to cool the regeneration air B with heat of evaporation. The restrictions
330
,
250
may comprise orifices, capillary tubes, expansion valves, or the like.
The refrigerant C which has been evaporated into a vapor in the evaporator
210
is introduced into the suction side of the refrigerant compressor
260
through the path
201
, and thus the above cycle is repeated. In this manner, the heat pump HP
1
pumps heat from low-temperature regeneration air as a low-temperature heat source to high-temperature regeneration air as a high-temperature heat source.
The dehumidifying apparatus
21
simultaneously regenerates the desiccant and removes moisture from the regeneration air, with the heat pump HP
1
, and preheats the regeneration air B before regenerating the desiccant and precools the regeneration air B after regenerating the desiccant, with the internal operating medium. Therefore, the dehumidifying apparatus
21
is simple in structure, and has a high moisture removal as most of the cooling effect of the heat pump can be used to condense the moisture in the air.
When the air is to be cooled and dehumidified, if the air is cooled directly to its dew point, then the amount of cooling is large. Therefore, a considerable portion of the cooling effect of the heat pump is consumed to cool the air, so that the moisture removal (dehumidifying performance) per electric power consumption is low. For this reason, the air-to-air heat exchanger
300
is provided across the evaporator
210
to precool and reheat (preheat) the regeneration air B, thereby reducing the sensible heat factor and reducing the amount of cooling down to the dew point.
In addition to providing a high moisture removal, the dehumidifying apparatus
21
can recover the heat to cool to the dew point for use as the heat to heat the regeneration air. Therefore, the desiccant can perform the moisture removal with a small amount of electric power. Since the amount of heat required is smaller than the amount of heat needed by a conventional electric heater, and the heat pump HP
1
has a high energy efficiency, the electric power consumption of the dehumidifying apparatus is small.
A mechanical arrangement of the dehumidifying apparatus
21
described above will be described below with reference to FIG.
2
. In
FIG. 2
, devices of the dehumidifying apparatus are housed in a cabinet
700
. The cabinet
700
comprises a housing of thin steel sheets in the form of a rectangular parallelepiped, and is divided into an upper region
700
A and a lower region
700
B which are located vertically with respect to each other and sealed from each other, by a horizontal flat partition plate
701
. The upper region
700
A defines a process air chamber
702
through which the process air A flows from the left-hand end to the right-hand end thereof. The lower region
700
B primarily defines a regeneration air chamber
703
in which the regeneration air B is circulated as described later. The lower region
700
B includes a space positioned away from the regeneration air chamber
703
for housing the compressor
260
and the drain tank
450
. The partition plate
701
may comprise a thin steel sheet which is similar to those of the cabinet
700
.
The arrangement of devices in the process air chamber
702
will first be described below. An air inlet port
104
is opened in a vertically uppermost portion of a left side panel
704
A of the cabinet
700
, for drawing the process air A from the air-conditioned space
101
(see FIG.
1
). The air inlet port
104
is an opening of the process air chamber
702
, so that the process air A drawn from the air inlet port
104
flows through the process air chamber
702
. A filter
501
is provided near the air inlet port
104
of the process air chamber
702
for preventing dust in the air-conditioned space
101
from entering the dehumidifying apparatus. The air blower
102
is disposed inwardly of the filter
501
, and the process air A flowing from the air inlet port
104
through the filter
501
into the process air chamber
702
is drawn by the air blower
102
. The path
107
is defined between the air inlet port
104
and the air blower
102
. The process air A is caused to flow through the process air chamber
702
by the air blower
102
.
The process air A discharged from the air blower
102
flows through the path
108
, flows horizontally into an upper half of the desiccant wheel
103
, and is dehumidified by the desiccant of the desiccant wheel
103
. The process air A which has flowed horizontally from the upper half of the desiccant wheel
103
passes through the path
109
, flows out of the process air chamber
702
(i.e., flows out of the cabinet
700
) from an outlet port
110
which is opened in an vertically uppermost portion of a right side panel
704
B of the cabinet
700
, and is returned and supplied to the air-conditioned space
101
.
The desiccant wheel
103
extends through an opening
706
defined in the partition plate
701
with its rotational axis AX being horizontally oriented. The desiccant wheel
103
has a semicircular upper half disposed in the process air chamber
702
and a semicircular lower half disposed in the an upper region
703
A, described later, of the regeneration air chamber
703
. An electric motor
105
as an actuator is disposed near the desiccant wheel
103
in the upper region
703
A, described later, of the process air chamber
703
with its rotational axis being horizontally oriented. The electric motor
105
and the desiccant wheel
103
are operatively connected to each other by a chain
131
, which transmits the rotation of the electric motor
105
to the desiccant wheel
103
to rotate the desiccant wheel
103
at a rotational speed ranging from 15 to 20 revolutions per hour. Since the rotational axis AX of the desiccant wheel
103
is oriented horizontally, the cabinet
700
can be constructed in a compact size with its horizontal length being reduced.
The height of the process air chamber
702
is slightly larger than the radius of the desiccant wheel
103
, and the height of the regeneration air chamber
703
is slightly smaller than twice the radius of the desiccant wheel
103
. The regeneration air chamber
703
has a horizontal flat partition plate
707
disposed therein which is spaced downwardly from the partition plate
701
by a distance slightly larger than the radius of the desiccant wheel
103
. The partition plate
707
divides the regeneration air chamber
703
into vertically spaced upper and lower regions
703
A,
703
B. The partition plate
707
has openings
705
A,
705
B defined respectively in its opposite ends, for allowing the regeneration air B to circulate in the upper and lower regions
703
A,
703
B therethrough.
The arrangement of devices in the regeneration air chamber
703
will be described below. A filter
502
is disposed in a right-hand portion of the upper region
703
A of the regeneration air chamber
703
, for removing dust from the regeneration air B which flows upwardly from the lower region
703
B through the right opening
705
B and then flows horizontally. The condenser
220
having a coiled heat exchange tube is disposed on the left-hand side of the filter
502
. The regeneration air B which has passed through the filter
502
passes through the condenser
220
, and is heated thereby. The regeneration air B which has passed through the condenser
220
and the path
125
flows horizontally into the lower half of the desiccant wheel
103
, thus regenerating the desiccant. The regeneration air B which has flowed horizontally out of the lower half of the desiccant wheel
103
flows through the path
126
a
into the heat exchanger
340
, and is cooled thereby. The regeneration air B which has passed through the heat exchanger
340
and the path
126
b
flows into the first compartment
310
of the heat exchanger
300
, and is precooled thereby.
External air as another fluid is introduced into the heat exchanger
340
through a duct (not shown). When the cabinet
700
is not installed in the air-conditioned space
101
, a duct for introducing external air into the heat exchanger
340
is not required. In this case, air in the environment where the cabinet
700
is installed is used directly as a fluid for exchanging heat with the regeneration air. The heat exchanger
340
may use cooling water instead of external air. When cooling water is to be used, a cooling water supply pipe and a return pipe are connected to the heat exchanger
340
.
The arrangement of the heat exchanger
300
will be described below. The heat exchanger
300
extends through an opening
708
defined in the partition plate
707
and is accommodated in the upper and lower regions
703
A,
703
B of the regeneration air chamber
703
. The first compartment
310
of the heat exchanger
300
is disposed in the upper region
703
A, and the second compartment
320
of the heat exchanger
300
is disposed in the lower region
703
B.
The regeneration air B which has flowed out of the first compartment
310
of the heat exchanger
300
is drawn through the path
127
into the air blower
140
which circulates the regeneration air B in the regeneration air chamber
703
. The regeneration air B discharged from the air blower
140
passes through the path
128
which is extremely short and the evaporator
210
having a coiled heat exchange tube, and is cooled by the evaporator
210
. While the regeneration air B is then flowing through the path
129
, it changes its direction to a vertically downward direction, and passes through the left opening
705
A. The regeneration air B which has passed through the opening
705
A changes its direction to a horizontal direction, flows horizontally in the lower region
703
B of the regeneration air chamber
703
, and flows into the second compartment
320
of the heat exchanger
300
where the regeneration air B is preheated. The drain tank
450
and the compressor
260
are disposed in a portion of the regeneration air chamber
703
which is horizontally closer to the viewer of FIG.
2
. The regeneration air B which has flowed out of the second compartment
320
of the heat exchanger
300
flows through the path
124
, changes its direction to a vertically upward direction, passes through the right opening
705
B, then changes its direction to a horizontal direction, and reaches the filter
502
. Thereafter, the regeneration air B circulates repeatedly through the above flows.
The arrangement of devices constituting the heat pump HP
1
through which the refrigerant C flows will be described below. The compressor
260
and the drain tank
450
are disposed beneath the partition plate
707
away from the lower region
703
B of the regeneration air chamber
703
. The compressor
260
is disposed substantially directly beneath the desiccant wheel
103
as viewed from the viewer of
FIG. 2
, and the drain tank
450
is disposed substantially directly beneath the evaporator
210
. The paths
201
through
204
are disposed to connect the devices as shown in FIG.
1
.
In the above arrangements, the devices are arranged such that the process air A flows horizontally, and the regeneration air B flows mainly horizontally and slightly vertically for circulation. However, the devices may be arranged such that the process air A flows vertically, and the regeneration air B flows mainly vertically and slightly horizontally for circulation.
Next, operation of the heat pump HP
1
will be described with reference to FIG.
3
.
FIG. 3
is a Mollier diagram in the case where HFC134a is used as the refrigerant C.
FIG. 1
will be referred to for the description of the devices. In the Mollier diagram, the horizontal axis represents the enthalpy h (kJ/kg), and the vertical axis represents the pressure p (MPa). In addition to the above refrigerant, HFC407C and HFC410A are suitable refrigerants for the heat pump and the dehumidifying air-conditioning apparatus
21
(see
FIG. 1
) according to the present invention. These refrigerants have an operating pressure region shifted toward a higher pressure side than HFC134a.
In
FIG. 3
, a point “a” represents a state of the refrigerant at the outlet port of the evaporator
210
shown in
FIG. 1
, and the refrigerant is in the form of a saturated vapor. The refrigerant has a pressure of 0.30 MPa, a temperature of 1° C., and an enthalpy of 399.2 kJ/kg. A point b represents a state of the vapor drawn and compressed by the compressor
260
, i.e., a state at the outlet port of the compressor
260
. In the point b, the refrigerant has a pressure of 1.89 MPa and is in the form of a superheated vapor.
The refrigerant vapor C is cooled in the condenser
220
and reaches a state represented by a point c in the Mollier diagram. In the point c, the refrigerant is in the form of a saturated vapor and has a pressure of 1.89 MPa and a temperature of 65° C. Under this pressure, the refrigerant is cooled and condensed to reach a state represented by a point d. In the point d, the refrigerant is in the form of a saturated liquid and has the same pressure and temperature as those in the point c. The saturated liquid has an enthalpy of 295.8 kJ/kg.
The refrigerant liquid C is depressurized by the restriction
330
and flows into the condensing section
252
A in the heat exchanger
300
. This state is indicated at a point e on the Mollier diagram. The pressure of the refrigerant liquid is an intermediate pressure according to the present invention, i.e., is of an intermediate value between 0.30 MPa and 1.89 MPa in the present embodiment. The intermediate pressure is a saturated pressure at a temperature of 15° C. in the present embodiment. The refrigerant liquid is a mixture of the liquid and the vapor because part of the liquid is evaporated.
In the condensing section
252
A, the refrigerant liquid C is condensed under the intermediate pressure, and reaches a state represented by a point f
1
on the saturated liquid curve under the intermediate pressure.
The refrigerant C in the state represented by the point f
1
flows into the evaporating section
251
A. In the evaporating section
251
A, the refrigerant C removes heat from the regeneration air B having a relatively high temperature and flowing through the first compartment
310
, and is evaporated. The refrigerant C further flows into the evaporating section
251
B and reaches a state represented by a point g
1
, which is located intermediately between the saturated liquid curve and the saturated vapor curve. In the point g
1
, while part of the liquid is evaporated, the refrigerant liquid C remains in a considerable amount.
The refrigerant C in the state represented by the point g
1
flows into the condensing section
252
B and then into the condensing section
252
C. The refrigerant C is cooled in these condensing sections, increases its liquid phase, reaches a state represented by a point f
2
on the saturated liquid curve, and then flows into the evaporating section
251
C and then into the evaporating section
251
D. In these evaporating sections, the refrigerant C increases its liquid phase, and then reaches a state represented by a point g
2
. Similarly, the refrigerant C is condensed in the next condensing section
252
D and reaches a state represented by a point f
3
on the saturated liquid curve. In this manner, while the refrigerant C is being repeatedly condensed and evaporated, it exchanges heat between the regeneration air having a low temperature and the regeneration air having a high temperature. The condensed refrigerant C in the state at the point f
3
is then introduced into the expansion valve
250
.
On the Mollier diagram, the point f
3
is on the saturated liquid curve. In this point, the refrigerant has a temperature of 15° C. and an enthalpy of 220.5 kJ/kg. The refrigerant liquid C at the point f
3
is depressurized to 0.30 MPa, which is a saturated pressure at a temperature of 1° C., by the restriction
250
, and reaches a state represented by a point j. The refrigerant C at the point j flows as a mixture of the refrigerant liquid C and the vapor at a temperature of 1° C. into the evaporator
210
, where the refrigerant removes heat from the process air A and is evaporated into a saturated vapor at the state indicated by the point a on the Mollier diagram. The evaporated vapor is drawn again by the compressor
260
, and thus the above cycle is repeated.
When the dehumidifying apparatus is arranged such that the refrigerant at the state e is not evaporated in the evaporating section
251
as in the present embodiment but is first condensed in the condensing section
252
, the amount of the refrigerant in a vapor phase which passes through the restriction
250
under volume control is reduced because the refrigerant becomes close to a two-phase state. Therefore, a cooling effect is maintained at a high level.
In the heat exchanger
300
, as described above, the refrigerant C goes through changes of the condensed state from the point e to the point f
1
or from the point g
1
to the point f
2
in the condensing section
252
, and goes through changes of the evaporated state from the point f
1
to the point g
1
or from the point f
2
to the point g
2
in the evaporating section
251
. Since the refrigerant transfers heat by way of condensation and evaporation, the rate of heat transfer is very high.
In the vapor compression type heat pump HP
1
including the compressor
260
, the condenser
220
, the restrictions
330
,
250
, and the evaporator
210
, when the heat exchanger
300
is not provided, the refrigerant C at the state represented by the point d in the condenser
220
is returned to the evaporator
210
through the restrictions
250
. Therefore, the enthalpy difference that can be used by the evaporator
210
is only 399.2−295.8=103.4 kJ/kg. With the heat pump HP
1
according to the present embodiment which has the heat exchanger
300
, however, the enthalpy difference that can be used by the evaporator
210
is 399.2−220.5=178.7 kJ/kg. Thus, the amount of vapor that is circulated to the compressor
260
under the same cooling load and the required power can be reduced by 42%. Consequently, the heat pump HP
1
according to the present embodiment can perform the same operation as with a subcooled cycle.
Since the refrigerant enthalpy at the inlet of the evaporator
210
is reduced due to the economizer effect of the heat pump and the cooling effect of the refrigerant per unit flow rate is high, the moisture removal effect and the energy efficiency are increased.
Operation of the dehumidifying apparatus
21
having the heat pump HP
1
will be described below with reference to a psychrometric chart shown in FIG.
4
.
FIG. 1
will be referred to for structural details. In
FIG. 4
, the alphabetical letters K, L, P and R represent states of air in various regions, and correspond to the alphabetical letters which are encircled in the flow diagram shown in FIG.
1
. The psychrometric chart shown in
FIG. 4
is also applicable to a dehumidifying apparatus according to second and third embodiments of the present invention which will be described later.
In
FIG. 1
, the process air A (in a state K) from the air-conditioned space
101
is drawn through the process air path
107
into the air blower
102
, discharged from the air blower
102
, and delivered through the path
108
into the desiccant wheel
103
. The process air A from which moisture has been desorbed by the desiccant wheel
103
and hence which has been dried has its absolute humidity lowered to 2 g/kgDA and its dry-bulb temperature increased (state L). The process air A is then returned through the path
109
to the air-conditioned space
101
. “DA” in the unit of the absolute humidity stands for Dry Air.
The regeneration air B (in a state P) having an absolute humidity of 5 g/kgDA and a dry-bulb temperature of 5° C., which has flowed out of the evaporator
210
, is delivered through the path
129
into the second compartment
320
of the heat exchanger
300
. In the second compartment
320
, the regeneration air B is heated to a certain extent by the refrigerant C which is condensed in the condensing section
252
, to increase its dry-bulb temperature (intermediate between 5° C. and 60° C.) and to keep its absolute humidity constant (state R). This process can be referred to as preheating because the regeneration air B is preliminary heated before being heated by the condenser
220
.
The preheated regeneration air B is introduced through the path
124
into the condenser
220
. The regeneration air B is heated by the condenser
220
to increase its dry-bulb temperature to 60° C., with constant absolute humidity (state T). The regeneration air B is further delivered through the path
125
into the desiccant wheel
103
, where the regeneration air B removes heat from the desiccant (not shown in
FIG. 1
) in the dry elements, thus regenerating the desiccant. The regeneration air B itself increases its absolute humidity to 10 g/kgDA, and reduces its dry-bulb temperature due to heat of desorption of moisture from the desiccant (state Ua).
The regeneration air B which has flowed out of the desiccant wheel
103
is delivered through the path
126
a
into the heat exchanger
340
, where the regeneration air B lowers its dry-bulb temperature with constant absolute humidity (state Ub).
The regeneration air B which has flowed out of the heat exchanger
340
is delivered through the path
126
b
into the first compartment
310
of the heat exchanger
300
. In the first compartment
310
of the heat exchanger
300
, the regeneration air B is cooled to a certain extent by the refrigerant C which is evaporated in the evaporating section
251
to lower its dry-bulb temperature and to keep its absolute humidity constant (state V). This process can be referred to as precooling because the regeneration air B is preliminary cooled before being cooled to a temperature equal to or lower than its dew point by the evaporator
210
. The regeneration air B is drawn through the path
127
by the air blower
140
and discharged into the path
128
. The discharged regeneration air B is delivered through the path
128
into the evaporator
210
, where the regeneration air B is dehumidified and cooled to a temperature equal to or lower than its dew point, for thereby lowering its absolute humidity to 5 g/kgDA and its dry-bulb temperature to 5° C. (state P). The regeneration air B which has flowed out of the evaporator
210
repeats the same cycle.
In the heat exchanger
300
, the regeneration air B is precooled by the evaporation of the refrigerant C in the evaporating section
251
and heated by the condensation of the refrigerant C in the condensing section
252
. The refrigerant C evaporated in the evaporating section
251
is condensed in the condensing section
252
. Thus, the evaporation and condensation of the same refrigerant C causes indirect heat exchange between the regeneration air B before being cooled by the evaporator
210
and the regeneration air B after being cooled by the evaporator
210
.
In the air cycle on the psychrometric chart shown in
FIG. 4
, the amount of heat Q with which the regeneration air B is heated in the second compartment
320
corresponds to heating with use of waste heat, the amount of heat i with which the regeneration air B is heated by the evaporator
210
corresponds to a cooling effect, and the amount of heat recovered by the heat exchanger
300
as an economizer is represented by H. The heat exchanger
340
removes heat from the regeneration air B by the amount of heat Q
1
to cool the regeneration air B. Since the regeneration air B is cooled to a certain extent by the heat exchanger
340
and then flows into the heat exchanger
300
, the temperature of the regeneration air B flowing into the evaporator
210
is lowered closely to its dew point, for thereby increasing the moisture removal of the heat pump per cooling effect. The amount of heat that is discharged as a whole when the moisture in a vapor phase in the air-conditioned space is converted into a liquid phase and stored in the tank
450
and the amount of heat corresponding to the drive power of the compressor
260
can be discharged from the dehumidifying system through the heat exchanger
340
(not shown in FIG.
3
).
A behavior of the refrigerant C in the evaporating sections and the condensing sections of the heat exchanger
300
will be described below with reference to FIG.
5
. The refrigerant C which is reduced in pressure by the restriction
330
and which comprises a mixture of a liquid phase and a vapor phase with the refrigerant liquid being partly expanded flows into the condensing section
252
A. While the refrigerant C is flowing through the condensing section
252
A, the refrigerant C preheats the regeneration air B, and heat is removed from the refrigerant C itself to reduce the vapor phase of the refrigerant, and then the refrigerant C flows into the evaporating section
251
A. In the evaporating section
251
A, the refrigerant C cools the regeneration air B having a higher temperature than the regeneration air B in the condensing section
252
A, and flows into the next evaporating section
251
B while heat is applied to the refrigerant C itself to evaporate the refrigerant C in a liquid phase. While the refrigerant C is flowing through the evaporating section
251
B, heat is further applied to the refrigerant C by the regeneration air B having a higher temperature to further evaporate the refrigerant C in a liquid phase. Then, the refrigerant C flows into the next condensing section
252
B.
In the heat exchanger
300
, as described above, the refrigerant C changes in phase between the vapor phase and the liquid phase while flowing through the refrigerant path. Thus, heat is exchanged between the regeneration air B before being cooled by the evaporator
210
and the regeneration air B which has been cooled by the evaporator
210
to lower its absolute humidity.
In the dehumidifying apparatus
21
, the heat exchanger
300
is used as a precooling/preheating heat exchanger, and the operating fluid of the heat exchanger
300
and the operating fluid (i.e., the refrigerant) of the heat pump HP
1
are the same. Since the process of charging the refrigerant can be shared by the heat exchanger
300
and the heat pump HP
1
, the cost of manufacture and the cost of maintenance of the dehumidifying apparatus
21
can be reduced. The precooling/preheating heat exchanger can be manufactured as a unitary assembly. Because the refrigerant as the operating fluid flows as the refrigerant of the heat pump in one direction through the refrigerant path, no wick is required in the heat pipe, and hence the heat exchanger can be manufactured by production facilities for producing ordinary air/refrigerant heat exchangers, which have no wick. Accordingly, the heat exchanger can be manufactured at a low cost.
A second embodiment of the present invention will be described below with reference to FIG.
6
. The second embodiment differs from the first embodiment in that a heat exchanger
340
a
is used instead of the heat exchanger
340
. The heat exchanger
340
a
has a structure similar to the heat exchanger
340
.
The heat exchanger
340
a
has evaporating sections
341
A,
341
B and condensing sections
342
A,
342
B. The evaporating sections
341
A,
341
B correspond to the evaporating sections
251
A,
251
B of the heat exchanger
300
, and the condensing sections
342
A,
342
B correspond to the condensing sections
252
A,
252
B of the heat exchanger
300
. While the evaporating sections and the condensing sections are shown as being considerably spaced apart from each other, they should preferably be in the form of a group of integral thin pipes as with the heat exchanger
300
.
The evaporating sections extend through a first compartment
343
and the condensing sections extend through a second compartment
344
. The first compartment
343
is inserted between the desiccant wheel
103
and the first compartment
310
of the heat exchanger
300
. The regeneration air B which has passed through the desiccant wheel
103
passes through the first compartment
343
of the heat exchanger
340
a,
and then flows into the first compartment
310
of the heat exchanger
300
.
The second compartment
344
of the heat exchanger
340
a
is arranged such that external air is allowed to pass therethrough by an air blower
144
.
The refrigerant pipe
203
extending into the condensing section
342
A has a restriction
336
disposed thereon. The dehumidifying apparatus is arranged such that the heat exchanger
340
a
is inserted on the refrigerant pipe
203
according to the first embodiment as viewed along the flow of the refrigerant. The refrigerant C flows through the condensing section
342
A, the evaporating section
341
A, the evaporating section
341
B, and the condensing section
342
B, and then reaches the restriction
330
. In this time, heat is transferred from the regeneration air B passing through the first compartment
343
to external air passing through the second compartment
344
by the condensation and evaporation of the refrigerant, as with the heat exchanger
300
.
Operation of a heat pump HP
2
will be described with reference to FIG.
7
.
FIG. 7
is a Mollier diagram plotted in the case where HFC134a is used as the refrigerant C, as with FIG.
3
. Details of operation which are the same as those described with reference to
FIG. 3
will not be described below.
In
FIG. 7
, points a, b, c, d are the same as those shown in FIG.
3
. The refrigerant liquid C in the state represented by the point d is reduced in pressure by the restriction
336
and flows into the condensing section
342
A of the heat exchanger
340
a.
This state is indicated by a point “e” on the Mollier diagram. The pressure of the refrigerant is an intermediate pressure according to the present invention, and is of an intermediate value between 0.30 MPa and 1.89 MPa in the present embodiment. The intermediate pressure is higher to a certain extent than a saturated pressure at a temperature of 13° C. The refrigerant C is a mixture of the liquid and the vapor because part of the liquid is evaporated.
In the condensing section
342
A, the refrigerant C is condensed under the intermediate pressure, and reaches a state represented by a point f
1
on a saturated liquid curve under the intermediate pressure.
The refrigerant C in the state indicated by the point f
1
flows into the evaporating section
341
A. In the evaporating section
341
A, the refrigerant C removes heat from the regeneration air B having a relatively high temperature and flowing through the first compartment
343
, and is evaporated. The refrigerant C further flows into the evaporating section
341
B, and reaches a state represented by a point g
1
, which is located intermediately between the saturated liquid curve and the saturated vapor curve. In the point g
1
, while part of the liquid is evaporated, the refrigerant liquid C remains in a considerable amount.
The refrigerant C in the state represented by the point g
1
flows into the condensing section
342
B, is cooled to increase its liquid phase, and reaches a state represented by a point f
2
on the saturated liquid curve. The refrigerant liquid C is reduced in pressure by the restriction
330
, and flows into the condensing section
252
A of the heat exchanger
300
. Subsequent operation is the same as the operation described above with reference to
FIG. 3
, and will not be described below. The points f
1
, g
1
, f
2
, g
2
, f
3
shown in
FIG. 3
are changed respectively to points f
3
, g
3
, f
4
, g
4
, f
5
in FIG.
7
. The operating temperature of the heat exchanger
300
is lowered to a certain extent from 15° C. to 13° C. because the refrigerant C is efficiently cooled by the heat exchanger
340
a.
With the above arrangement, since the heat pump has the heat exchanger
304
a
which utilizes heat transfer by way of condensation and evaporation, the regeneration air B can be cooled with an excellent rate of heat transfer. The cooling effect of the refrigerant can further be increased.
A third embodiment of the present invention will be described below with reference to
FIGS. 8 and 9
. The third embodiment differs from the first embodiment shown in
FIG. 1
in that the refrigerant flows from the restriction
330
first into the evaporating section
251
A of a heat exchanger
300
b,
the refrigerant moves from the plane PA to the plane PB between the condensing sections
252
A,
252
B (the movement of the refrigerant between the other planes is successively shifted), a plane PE is added, and restrictions
331
,
332
are provided between the evaporating sections in the planes PB, PC and between the evaporating sections in the planes PD, PE. Specifically, as shown in
FIG. 8
, the end of the evaporating section
251
B in the plane PB and the end of the evaporating section
251
C in the plane PC are connected to each other via the restriction
331
, and the end of the evaporating section
251
D in the plane PD and the end of the evaporating section
251
E in the plane PE are connected to each other via the restriction
332
. Other structural details are identical to those shown in FIG.
1
and are omitted from illustration.
The major change of the third embodiment from the first embodiment is the restrictions
331
,
332
disposed between the planes. Other changes do not cause a significant operational change except that the evaporation and condensation in the heat exchanger
300
b
are shifted as a whole to a vapor phase because the refrigerant flows from the restriction
330
first into the evaporating section
251
A. More planes than the planes PA through PE may be added, and more restrictions may be added accordingly.
In the above arrangement, the refrigerant C introduced into the evaporating section
251
A is partly evaporated into a two-phase state in the evaporating section
251
A, and flows into the condensing section
252
A. The refrigerant changes its direction in the U tube, and flows into the condensing section
252
B and the evaporating section
251
B. The refrigerant is partly evaporated in the evaporating section
251
B, is depressurized by the restriction
331
, and flows into the evaporating section
251
C in the plane PC. The refrigerant is further evaporated in the evaporating section
251
C, and then flows into the condensing section
252
C. The refrigerant changes its direction in the U tube, and flows into the condensing section
252
D. In the condensing section
252
D, the refrigerant is further condensed and then flows into the evaporating section
251
D. The refrigerant C is partly evaporated in the evaporating section
251
D, and reaches the restriction
332
. The refrigerant is depressurized by the restriction
332
, and flows into the evaporating section
251
E in the plane PE and subsequently into the condensing section
252
E in the plane PE. The refrigerant C is sufficiently condensed in the condensing section
252
E, and flows through the path
204
to the expansion valve
250
.
The evaporating pressures in the evaporating sections
251
A,
251
B and the condensing pressures in the condensing sections
252
A,
252
B, i.e., first intermediate pressures, or the pressures in the evaporating sections
251
C,
251
D and the condensing sections
252
C,
252
D, i.e., second intermediate pressures, depend on the temperature of the regeneration air B before flowing into the evaporator
210
and the temperature of the regeneration air B after flowing through the evaporator
210
and being cooled therein.
Since the heat exchanger
300
shown in
FIG. 1
or the heat exchanger
300
b
shown in
FIG. 8
utilizes heat transfer by way of evaporation and condensation, the heat exchanger has an excellent rate of heat transfer. Particularly, the heat exchanger
300
b
has a very high efficiency of heat exchange as it performs heat exchange of the regeneration air B on the counterflow principles as described later. Since the refrigerant C is forcibly caused to flow in a substantially one direction as a whole in the refrigerant paths, from the evaporating section
251
to the condensing section
252
or from the condensing section
252
to the evaporating section
251
, the efficiency of heat exchange between the regeneration air B having a high temperature and the regeneration air B having a low temperature is very high. The expression “the refrigerant flows in a substantially one direction as a whole” means that the refrigerant C flows in a substantially one direction in the refrigerant paths when viewed as a whole even though the refrigerant may locally flow back due to turbulences or be vibrated in the flowing direction due to pressure waves produced by bubbles or instantaneous interruptions. In the present embodiment, the refrigerant C is forced to flow in one direction under the pressure increased by the compressor
260
.
When the high-temperature fluid is cooled, i.e., the heat exchanger is used for cooling the high-temperature fluid, the efficiency φ of heat exchange is defined by
φ=(
TP
1
−
TP
2
)/(
TP
1
−
TC
1
)
where the temperature of the high-temperature fluid at the inlet of the heat exchanger is represented by TP
1
, the temperature thereof at the outlet of the heat exchanger by TP
2
, the temperature of the low-temperature fluid at the inlet of the heat exchanger by TC
1
, and the temperature thereof at the outlet of the heat exchanger by TC
2
. When the low-temperature fluid is to be heated, i.e., when the heat exchanger is used for heating the low-temperature fluid, the efficiency φ of heat exchange is defined by
φ=(
TC
2
−
TC
1
)/(
TP
1
−
TC
1
)
Operation of a heat pump HP
3
according to the third embodiment shown in
FIG. 8
will be described below with reference to
FIG. 9
(
FIG. 8
shows only part of components of the heat pump HP
3
, and
FIG. 1
will be referred to for other components). In
FIG. 9
, the transitions from the point a to the point e are identical to the first embodiment shown in FIG.
3
and will not be described below. The refrigerant C in the state represented by the point e which flows into the evaporating section
251
A in the heat exchanger
300
b
is a mixture of the liquid and the vapor with part of the liquid being evaporated under the first intermediate pressure, as described above with reference to FIG.
3
.
The refrigerant C is further evaporated in the evaporating section
251
A, and reaches a point f
1
nearer to the saturated vapor curve in the two-phase region on the Mollier diagram. The refrigerant C in this state flows into the condensing section
252
A, where the refrigerant is condensed. Then, refrigerant is reversed in direction by the U tube, flows into the condensing section
252
B, is further condensed, and reaches a point g
1
nearer to the saturated liquid curve though in the two-phase region. Then, the refrigerant flows into the evaporating section
251
B, goes toward the saturated vapor curve within the two-phase region to reach a point h
1
a.
Up to this point, the refrigerant undergoes changes substantially under the first intermediate pressure.
The refrigerant C in the state represented by the point h
1
a
is depressurized by the restriction
331
, and reaches a point h
1
b
under the second intermediate pressure. Specifically, the refrigerant flows from the evaporating section
251
B as the refrigerant path in the plane PB through the restriction
331
into the evaporating section
251
C as the refrigerant path in the plane PC. This refrigerant C is evaporated under the second intermediate pressure in the evaporating section
251
C, and reaches a point f
2
. The refrigerant is then repeatedly similarly evaporated into a vapor phase and condensed into a liquid phase alternately, and depressurized by the intermediate restriction
332
to a third intermediate pressure. Thereafter, the refrigerant C which flows through the refrigerant paths of the evaporating section
251
E and the condensing section
252
E reaches a point g
3
on the Mollier diagram which corresponds to the point f
3
in FIG.
3
. On the Mollier diagram, the point g
3
is on the saturated liquid curve. In this point, the refrigerant has a temperature of 11° C. and an enthalpy of 215.0 kJ/kg.
As in the case of
FIG. 3
, the refrigerant liquid C at the point g
3
is depressurized to 0.30 MPa, which is a saturated pressure at a temperature of 1° C., by the restriction
250
, and reaches a state represented by a point j. The refrigerant flows as a mixture of the refrigerant liquid C and the vapor at a temperature of 1° C. into the evaporator
210
, where the refrigerant removes heat from the regeneration air B and evaporated into a saturated vapor at the state indicated by the point a on the Mollier diagram. The evaporated vapor is drawn again by the compressor
260
, and thus the above cycle is repeated.
In the heat exchanger
300
b,
as described above, the refrigerant C repeatedly goes alternately through changes of vapor phase and changes of liquid phase. Since the refrigerant transfers heat by way of evaporation and condensation, the rate of heat transfer is very high, as with the heat exchanger
300
in the first embodiment.
In the heat exchanger
300
b,
the regeneration air B before being cooled in the evaporator
210
exchanges heat successively in the evaporating sections
251
A,
251
B,
251
C,
251
D,
251
E in the first compartment
310
. Specifically, the temperature gradient of the regeneration air B and the temperature gradient of the evaporating section
251
are in the same direction. Similarly, the regeneration air B after being cooled in the evaporator
210
exchanges heat successively in the condensing sections
252
E,
252
D,
252
C,
252
B,
252
A in the second compartment
320
. Specifically, the temperature gradient of the regeneration air B and the temperature gradient of the condensing section
252
are in the same direction. Thus, heat exchange is performed between the counterflows of the regeneration air B before being cooled in the evaporator
210
and the regeneration air B after being cooled in the evaporator
210
. Such heat exchange, together with the heat transfer by way of evaporation and condensation, allows the heat exchanger
300
b
to achieve a very high efficiency of heat exchange.
The enthalpy difference that can be used by the evaporator
210
is remarkably larger than that in the conventional heat pump. Thus, the amount of vapor that is circulated to the compressor under the same cooling load and the required power can be reduced by 20% (1−(620.1−472.2)/(620.1−434.9)=0.20), as in the case of FIG.
3
.
Operation of the dehumidifying apparatus with the heat pump HP
3
will not be described below as it is qualitatively the same as described above with reference to the psychrometric chart of FIG.
4
.
FIG. 10
shows a flow diagram of a dehumidifying apparatus
23
according to a fourth embodiment of the present invention. According to the fourth embodiment, a heat exchanger
300
c,
which corresponds to the heat exchanger
300
according to the first embodiment and the heat exchanger
300
b
according to the second embodiment, has restrictions
331
,
332
disposed at the condensing section
252
side. Other structural details of the fourth embodiment are identical to those of the second embodiment shown in FIG.
8
.
FIG. 11
is a Mollier diagram of a heat pump HP
4
shown in FIG.
10
. Unlike the Mollier diagram shown in
FIG. 9
, the refrigerant is depressurized in the condensing process under the intermediate pressure. Specifically, the refrigerant is depressurized from a point g
1
a
to a point g
1
b
by the restriction
331
and depressurized from a point g
2
a
to a point g
2
b
by the restriction
332
. The fourth embodiment is also the same as the embodiment shown in
FIG. 9
in that heat exchange is performed between the counterflows of the regeneration air B before being cooled in the evaporator
210
and the regeneration air B after being cooled in the evaporator
210
.
The restrictions may be provided as a combination of the restrictions shown in
FIGS. 8 and 10
, and disposed on both sides of the evaporating sections and the condensing sections. With this arrangement, each time the refrigerant moves from one plane to the next plane, it flows through a restriction, and the evaporating temperatures/condensing temperatures differ in each plane, so that the flows of the regeneration air between which heat is to be exchanged become nearly perfect counterflows.
A drain pan
451
is shown in
FIGS. 1 and 6
, and such a drain pan is preferably located below not only the evaporator
210
, but also the heat exchangers
300
,
300
b,
300
c.
Particularly, the drain pan
451
is preferably disposed below the first compartment
310
because the regeneration air B is mainly precooled in the first compartment
310
of the heat exchangers
300
,
300
b,
300
c
and some moisture may possibly be condensed therein.
An example of a structure of the heat exchanger
300
d
according to the present invention will be described below with reference to FIGS.
12
(
a
) and
12
(
b
). FIG.
12
(
a
) is a drawing showing the heat exchanger as viewed in the direction in which the regeneration air B having a low temperature and the regeneration air B having a high temperature are flowing, and FIG.
12
(
b
) is a drawing of side elevational view showing the heat exchanger as viewed in a direction perpendicular to the flows of the low-temperature regeneration air and the high-temperature regeneration air. Specifically, FIG.
12
(
a
) is a view as viewed from an arrow taken along a line A—A of FIG.
12
(
b
). In FIG.
12
(
a
), the high-temperature regeneration air B flows through the compartment
310
away from the viewer, and the low-temperature regeneration air B through the compartment
320
toward the viewer. In the heat exchanger
300
d,
tubes are disposed in eight rows in each of the four planes PA, PB, PC, PD which lie perpendicularly to the flows of the low-temperature regeneration air B and the high-temperature regeneration air B. Thus, the tubes are arranged in four tiers and eight rows along the flows of the regeneration air B. A plane PE, not shown, may be provided below the plane PD, and eight rows of tubes may be disposed in the plane PE. In
FIGS. 1
,
5
,
6
,
8
and
10
, the heat exchange tube is disposed in one row per tier in each of the planes PA, PB, PC and PD for illustrative purpose. Typically, however, the tubes are provided in a plurality of rows per tier. In this manner, the tubes constitute a group of thin pipes.
An intermediate restriction
331
is disposed in a transitional location from the first plane PA to the next plane PB. An intermediate restriction
332
(not shown) is disposed in a transitional location from the plane PB to the plane PC. An intermediate restriction
333
is disposed in a transitional location from the plane PC to the plane PD. While one restriction is provided in a transitional location from one plane to the next, tube rows in the plane PA may be arranged in a plurality of layers. In such an arrangement, an intermediate restriction is disposed in a transitional location from each layer to the next. Planes prior and subsequent to an intermediate restriction are referred to as first and second planes.
Heat exchangers each having tubes in eight rows and four layers (tiers) as shown in FIGS.
12
(
a
) and
12
(
b
) may be arranged parallel to each other or in series with each other with respect to the flows of the high- and low-temperature regeneration air, depending on the amount of the regeneration air.
In the Mollier diagram shown in
FIG. 11
, for example, the cycle is effective even if the refrigerant C is repeatedly evaporated and condensed into a subcooled region beyond the saturated liquid curve. In view of the heat exchange between the flows of the regeneration air, however, the refrigerant C should preferably change its phase in the two-phase region. With the heat exchanger
300
d
shown in FIGS.
12
(
a
) and
12
(
b
), therefore, the heat transfer area of the first evaporating section connected to the restriction
330
should preferably be larger than the heat transfer area of the succeeding evaporating section. Furthermore, since the refrigerant C flowing into the restriction
250
is preferably in the saturated or subcooled region, the heat transfer area of the condensing section connected to the restriction
250
should preferably be larger than the heat transfer area of the prior condensing section.
The heat exchanger according to the present invention is inexpensive and economical when being used instead of expensive heat pipes. Unlike heat pipes, the heat exchanger according to the present invention can be maintained with little effort because it can use the same operating fluid as in the heat pump.
A dehumidifying apparatus according to a fifth embodiment of the present invention will be described below with reference to
FIGS. 13 through 15
.
FIG. 13
is a flow diagram showing flows in the dehumidifying apparatus according to the fifth embodiment, and
FIG. 14
is a Mollier diagram of the refrigerant in a heat pump HP
5
included in the dehumidifying apparatus shown in FIG.
13
. In
FIG. 13
, a heat exchanger
300
e
and refrigerant and air paths connected thereto are shown, and other details are omitted from illustration. The fifth embodiment differs from the third embodiment shown in
FIG. 8
in that the heat exchanger
300
b
according to the third embodiment shown in
FIG. 8
is replaced with the heat exchanger
300
e.
Those parts or elements of the fifth embodiment which operates in the same manner or has the same functions as those of the third embodiment are denoted by the identical reference characters, and those parts or elements of the fifth embodiment which will not be described below are the same as those of the third embodiment.
In the present embodiment, the refrigerant path is branched into a plurality of paths (three paths in
FIG. 13
) downstream of the condenser
220
, i.e., branched refrigerant paths
51
through
53
, unlike the other embodiments. The branched refrigerant paths
51
through
53
are joined into a single refrigerant path
204
upstream of the evaporator
210
. Specifically, a plurality of branched refrigerant paths are provided between the condenser
220
and the evaporator
210
, and a first heat exchanging means and a second heat exchanging means are disposed in the branched refrigerant paths.
In other words, the dehumidifying apparatus according to the fifth embodiment has a plurality of thin pipe groups
51
(
52
,
53
) connected to the condenser
220
through the first restrictions
331
a
(
332
a,
333
a
) and alternatively extending through the first compartment
310
and the second compartment
320
repeatedly and then connected to the evaporator
210
through corresponding second restrictions
331
b
(
332
b,
333
b
), and a plurality of combinations of the first restrictions
331
a,
332
a,
333
a
and the second restrictions
331
b,
332
b,
333
b
which correspond respectively to the thin pipe groups
51
,
52
,
53
.
The branched refrigerant paths
51
through
53
alternately extend through a first heat exchanging portion (first compartment)
310
and a second heat exchanging portion (second compartment)
320
of the heat exchanger
300
e
repeatedly. The branched refrigerant paths
51
through
53
have the restrictions
331
a
through
333
a
upstream of the first heat exchanging portion
310
and the restrictions
331
b
through
333
b
downstream of the second heat exchanging portion
320
. These restrictions
331
a
through
333
b
may comprise orifices, capillary tubes, expansion valves, or the like, for example.
The first compartment
310
and the second compartment
320
are arranged such that the regeneration air flows as counterflows in the respective compartments
310
,
320
. In the first compartment
310
, the refrigerant paths
51
,
52
,
53
are arranged in the order named in the downstream direction of the regeneration air. In the second compartment
320
, the refrigerant paths
51
,
52
,
53
are arranged in the order named in the upstream direction of the regeneration air.
FIG. 15
is an enlarged view showing the branched refrigerant paths
51
through
53
in the heat exchanger
300
e
in the dehumidifying apparatus shown in FIG.
13
. The branched refrigerant paths
51
through
53
extend through the first heat exchanging portion
310
and the second heat exchanging portion
320
. As shown in.
FIG. 15
, the branched refrigerant path
51
has an evaporating section
251
A
a,
a condensing section
252
A
a,
a condensing section
252
A
b,
an evaporating section
251
A
b,
an evaporating section
251
A
c,
and a condensing section
252
A
c
arranged successively from the condenser
220
. Similarly, the branched refrigerant path
52
has an evaporating section
251
B
a,
a condensing section
252
B
a,
a condensing section
252
B
b,
an evaporating section
251
B
b,
an evaporating section
251
B
c,
and a condensing section
252
B
c,
and the branched refrigerant path
53
has an evaporating section
251
C
a,
a condensing section
252
C
a,
a condensing section
252
C
b,
an evaporating section
251
C
b,
an evaporating section
251
C
c,
and a condensing section
252
C
c.
In
FIG. 14
, the behavior of the refrigerant from the point a to the point d is the same as the behavior of the refrigerant in the third embodiment shown in
FIG. 9
, and will not be described below. The refrigerant liquid which has been cooled in the condenser
220
and has reached the state represented by the point d is branched into the branched refrigerant paths
51
through
53
and flows into the heat exchanger
300
e.
First, the refrigerant flowing through the refrigerant path
52
will be described below. The refrigerant liquid flowing into the refrigerant path
52
is depressurized by the restriction
332
a
and flows into the evaporating section
251
B
a
of the first heat exchanger
310
. This state of the refrigerant is indicated by a point e, and the refrigerant is a mixture of the liquid and the vapor because part of the liquid is evaporated. At this time, the pressure of the refrigerant is an intermediate pressure between the condensing pressure in the condenser
220
and the evaporating pressure in the evaporator
210
, i.e., is of an intermediate value between 1.89 MPa and 0.30 MPa in the present embodiment.
In the evaporating section
251
B
a,
the refrigerant liquid is evaporated under the intermediate pressure, and reaches a state represented by at a point f
1
which is located intermediately between a saturated liquid curve and a saturated vapor curve, under the intermediate pressure. In the point f
1
, while part of the liquid is evaporated, the refrigerant liquid C remains in a considerable amount. The refrigerant in the state represented by the point f
1
flows into the condensing sections
252
B
a,
252
B
b.
In the condensing sections
252
B
a,
252
B
b,
heat is removed from the refrigerant by low-temperature air in the state at a point P which flows through the second heat exchanger
320
, and the refrigerant reaches a state represented by a point g
1
.
The refrigerant in the state represented by the point g
1
flows into the evaporating sections
251
B
b,
251
B
c,
where heat is removed from the refrigerant. The refrigerant increases its liquid phase and reaches a state represented by a point f
2
. Then, the refrigerant flows into the condensing section
252
B
c,
where the refrigerant increases its liquid phase and reaches a state represented by a point g
2
. On the Mollier diagram, the point g
2
is on the saturated liquid curve. In this point, the refrigerant has a temperature of 11° C. and an enthalpy of 215.0 kJ/kg.
The refrigerant liquid at the point g
2
is depressurized to 0.30 MPa, which is a saturated pressure at a temperature of 1° C., by the restriction
332
b,
and reaches a state represented by a point q. The refrigerant at the point q flows as a mixture of the refrigerant liquid and the vapor at a temperature of 1° C. into the evaporator
210
, where the refrigerant removes heat from air in the state at a point V, and is evaporated into a saturated vapor at the state represented by the point a. The saturated vapor is drawn again by the pressurizer
260
, and thus the above cycle is repeated.
In the same manner as described above, the refrigerant flowing into the refrigerant path
51
passes through the restriction
331
a,
the evaporating sections, the condensing sections, and the restriction
331
b,
goes through states represented by points j, i
1
, k
1
, i
2
, k
2
, and reaches a state represented by a point l. The refrigerant flowing through the refrigerant path
53
passes through the restriction
333
a,
the evaporating sections, the condensing sections, and the restriction
333
b,
goes through states represented by points m, n
1
, o
1
, n
2
, o
2
, and reaches a state represented by a point r.
In the heat exchanger
300
e,
as described above, the refrigerant goes through changes of the evaporated state from the point e to the point f
1
or from the point g
1
to the point f
2
in the evaporating sections, and goes through changes of the condensed state from the point f
1
to the point g
1
or from the point f
2
to the point g
2
in the condensing sections. Since the refrigerant transfers heat by way of evaporation and condensation, the rate of heat transfer is very high and the efficiency of heat exchanger is high.
In the vapor compression type heat pump HP
5
including the pressurizer
260
, the condenser
220
, the restrictions
331
a
through
333
b,
and the evaporator
210
(other details than the heat exchanger
300
e
and the refrigerant and air paths are omitted from illustration in FIG.
13
), when the heat exchanger
300
e
according to the present invention is provided, the amount of vapor that is circulated to the pressurizer under the same cooling load and the required power can remarkably be reduced as with the third embodiment. Thus, the heat pump can perform the same operation as with a subcooled cycle. With the dehumidifying apparatus according to the present invention, since the enthalpy of the refrigerant at the inlet of the evaporator
210
is reduced due to the economizer effect of the heat pump HP
5
and the cooling effect of the refrigerant per unit flow rate is high, the moisture removal effect and the energy efficiency are increased.
While the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but may be carried out in various different forms with the scope of the technical ideas thereof. For example, the number of evaporating sections in the first heat exchanging portions in the refrigerant paths and the number of condensing sections in the second heat exchanging portions in the refrigerant paths are not limited to the illustrated examples. The number of the branched refrigerant paths in the fifth embodiment is not limited to the illustrated example, but the refrigerant path may be branched into any number of branched refrigerant paths.
Structural details of the desiccant wheel
103
for use in the embodiments of the present invention will be described below with reference to FIG.
16
. The desiccant wheel
103
comprises a thick disk-shaped wheel which is rotatable about a rotational axis AX, and a desiccant is filled into the wheel with gaps for allowing a gas to pass therethrough. For example, the desiccant wheel
103
comprises a number of tubular dry elements bounded to each other so that their central axes extend parallel to the rotational axis AX. The wheel is arranged so as to rotate in one direction about the rotational axis AX and also to allow the process air A and the regeneration air B to flow into and out of the desiccant wheel
103
parallel to the rotational axis AX. Each of the dry elements is positioned so as to alternately contact the process air A and the regeneration air B according to rotation of the desiccant wheel
103
. Generally, the desiccant wheel
103
is arranged so that the process air A and the regeneration air B flow as counterflows parallel to the rotational axis AX through respective substantially half areas of the circular desiccant wheel
103
.
The region through which the process air A flows and the region through which the regeneration air B flows are separated from each other by a partition plate (not shown in FIG.
16
). The desiccant wheel
103
rotates across the partition plate to bring the dry elements
103
a
into alternate contact with the process air A and the regeneration air B. In
FIG. 16
, the wheel is shown as being partly cut away to illustrate the dry elements
103
a
clearly.
The desiccant may be filled in the tubular dry elements as described above. The desiccant wheel
103
is arranged to allow the process air A and the regeneration air B to flow across the disk-shaped rotor.
In the embodiments described above, the same refrigerant C is used as a heat transfer medium in the evaporator
210
for cooling the regeneration air B to a temperature equal to or lower than its dew point, the first compartment
310
of the heat exchangers
300
,
300
b,
300
c,
300
d,
300
e
for precooling the regeneration air B, the condenser
220
for heating the regeneration air B, and the second compartment
320
of the heat exchangers
300
,
300
b,
300
c,
300
d,
300
e
for preheating the regeneration air B. Therefore, the refrigerant system is simplified. The refrigerant is positively circulated because the pressure difference between the evaporator
210
and the condenser
220
can be utilized. Since a boiling phenomenon with a phase change is applied to heat exchanges for precooling and preheating the process air, a high efficiency can be achieved.
The dehumidifying apparatus according to the above embodiments has been described as the dehumidifying apparatus for dehumidifying an air-conditioned space. However, the dehumidifying apparatus according to the present invention is applicable not only to the air-conditioned space, but also to other spaces that need to be dehumidified.
Industrial Applicability
According to the present invention, as described above, a dehumidifying apparatus comprises a moisture adsorbing device for removing moisture from process air and for being regenerated by desorbing moisture therefrom with regeneration air; and a heat pump having a condenser for condensing a refrigerant to heat said regeneration air at the upstream side of said moisture adsorbing device, an evaporator for evaporating said refrigerant to cool said regeneration air to a temperature equal to or lower than its dew point at the downstream side of said moisture adsorbing device, a pressurizer for raising a pressure of said refrigerant evaporated by said evaporator and delivering said refrigerant to said condenser, and a first heat exchanger for exchanging heat between said regeneration air flowing between said moisture adsorbing device and said evaporator and the regeneration air flowing between said evaporator and said condenser; wherein said regeneration air is used in circulation. Therefore, the regeneration air can be precooled by the heat exchanging means prior to cooling in the evaporator, and the amount of heat removed in the precooling process can be recovered from the regeneration air which has been cooled by the evaporator. Thus, a dehumidifying apparatus having a heat pump with a high coefficient of performance can be provided, and it is possible to provide a dehumidifying apparatus which consumes a small amount of energy per amount of moisture removal.
The moisture of the process air is not removed by being cooled by the evaporator, but is removed by the moisture adsorbing device. Therefore, it is possible to obtain air having a low dew point equal to or lower than an freezing point, i.e., a low absolute humidity of 4 g/kgDA or lower.
Claims
- 1. A dehumidifying apparatus comprising:a moisture adsorbing device for removing moisture from process air and for being regenerated by desorbing moisture therefrom with regeneration air; and a heat pump having a condenser for condensing a refrigerant to heat said regeneration air at the upstream side of said moisture adsorbing device, an evaporator for evaporating said refrigerant to cool said regeneration air to a temperature equal to or lower than its dew point at the downstream side of said moisture adsorbing device, a pressurizer for raising a pressure of said refrigerant evaporated by said evaporator and delivering said refrigerant to said condenser, and a first heat exchanger for exchanging heat between said regeneration air flowing between said moisture adsorbing device and said evaporator and the regeneration air flowing between said evaporator and said condenser; wherein said regeneration air is used in circulation.
- 2. A dehumidifying apparatus according to claim 1, wherein said first heat exchanger comprises a thin pipe group connecting said condenser and said evaporator to each other, for passing said refrigerant therethrough;wherein said thin pipe group is arranged so as to introduce said refrigerant condensed by said condenser to said evaporator and also to bring said refrigerant into alternate contact with said regeneration air flowing between said moisture adsorbing device and said evaporator and said regeneration air flowing between said evaporator and said condenser.
- 3. A dehumidifying apparatus according to claim 2, wherein said first heat exchanger has a first compartment for passing said regeneration air between said moisture adsorbing device and said evaporator, and a second compartment for passing said regeneration air between said evaporator and said condenser, said thin pipe group being connected to said condenser through a first restriction, extending alternately through said first compartment and said second compartment repeatedly, and then being connected to said evaporator through a second restriction.
- 4. A dehumidifying apparatus according to claim 3, further comprising a plurality of thin pipe groups connected to said condenser through said first restrictions and alternately extending through said first compartment and said second compartment repeatedly and then connected to said evaporator through said corresponding second restrictions, and a plurality of combinations of said first restrictions and said second restrictions which correspond respectively to the thin pipe groups.
- 5. A dehumidifying apparatus according to claim 3, wherein said first compartment and said second compartment are arranged such that said regeneration air flows as counterflows in the respective compartments; andsaid thin pipe groups in said first compartment and said second compartment have at least a pair of a first compartment extending portion and a second compartment extending portion in a first plane which is substantially perpendicular to the flow of said regeneration air, at least a pair of a first compartment extending portion and a second compartment extending portion in a second plane, different from said first plane, which is substantially perpendicular to the flow of said regeneration air, and an intermediate restriction disposed in a transitional location from said first plane to said second plane.
- 6. A dehumidifying apparatus according to any one of claims 1 through 5, further comprising a second heat exchanger disposed in a passage of the regeneration air used in circulation, for exchanging heat between said regeneration air and another fluid.
- 7. A dehumidifying apparatus according to claim 6, wherein said second heat exchanger comprises a second thin pipe group connecting said condenser and said first heat exchanger to each other, for passing the refrigerant therethrough; andsaid second thin pipe group is arranged so as to introduce said refrigerant condensed by said condenser to said first heat exchanger and also to bring said refrigerant into alternate contact with said regeneration air flowing between said moisture adsorbing device and said first heat exchanger and the other fluid.
- 8. A dehumidifying apparatus according to claim 6, wherein said other fluid comprises external air.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/JP01/04072 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO02/09308 |
11/21/2002 |
WO |
A |
US Referenced Citations (13)
Foreign Referenced Citations (7)
Number |
Date |
Country |
10-288421 |
Oct 1998 |
JP |
10-288486 |
Oct 1998 |
JP |
2000-356481 |
Dec 2000 |
JP |
2001-162131 |
Jun 2001 |
JP |
2001-215030 |
Aug 2001 |
JP |
WO9846957 |
Oct 1998 |
WO |
WO9846958 |
Oct 1998 |
WO |