ROOFTOP AIR CONDITIONING UNIT

Abstract

A rooftop air conditioning unit (RTU) is disclosed. The RTU comprises an absorber configured in a supply airstream, and a desorber configured in a regeneration airstream, wherein the desorber is fluidically connected to the absorber via a liquid desiccant system. The RTU further comprises a first heat exchanger configured upstream of the absorber in the supply airstream, a second heat exchanger configured upstream of the desorber in the regeneration airstream, and a third heat exchanger configured downstream of the absorber in the supply airstream, wherein the first heat exchanger and the third heat exchanger are fluidically connected to the second heat exchanger via a vapor compression system.

Description

BACKGROUND

This invention relates to the field of rooftop air conditioning units, and more particularly, a simple, improved, and efficient liquid desiccant-based rooftop air conditioning unit.

Existing rooftop air conditioning unit may involve a liquid desiccant system to provide dehumidification capabilities with a liquid desiccant contact media device installed downstream of an evaporator in the supply airstream. The non-isothermic process of the media device may condition the supply airstream. However, cooling or heating of the airstream prior to being supplied may be needed using separate vapor compression systems, additional heat exchangers and passive thermal devices, based on the state of the air coming out of the liquid desiccant device.

SUMMARY

Described herein is a rooftop air conditioning unit (RTU). The RTU comprises an absorber configured in a supply airstream, a desorber configured in a regeneration airstream, wherein the desorber is fluidically connected to the absorber via a liquid desiccant system; a first heat exchanger configured upstream of the absorber in the supply airstream, a second heat exchanger configured upstream of the desorber in the regeneration airstream, and a third heat exchanger configured downstream of the absorber in the supply airstream, wherein the first heat exchanger and the third heat exchanger are fluidically connected to the second heat exchanger via a vapor compression system.

In one or more embodiments, the RTU is configured to operate one or more of the first heat exchanger, the second first heat exchanger, and the third heat exchanger with the system as a condenser and/or an evaporator to adjust temperature and humidity of the supply airstream, downstream of the absorber, at predefined values.

In one or more embodiments, the supply airstream is to be cooled to provide the airstream of the predefined values downstream of the absorber, the first heat exchanger and/or the third heat exchanger is operated as the evaporator, and the second heat exchanger is operated as the condenser to reject heat of the supply airstream into the regeneration airstream.

In one or more embodiments, the RTU comprises one or more passive heat transfer systems fluidically configured between the supply air stream and the return air stream, and/or between the supply airstream and the regeneration airstream.

In one or more embodiments, the one or more passive heat transfer systems comprises enthalpy wheels and/or recirculated fluid loop.

In one or more embodiments, the RTU is adapted to be configured at an area of interest (AOI) to supply the airstream having the predefined values of the temperature and humidity at the AOI, and further receive the return airstream from the AOI.

In one or more embodiments, the RTU comprises a controller that is configured to: receive a set of instructions pertaining to the predefined values of the airstream to be supplied at the AOI; and control operation of one or more of the heat exchangers associated with the RTU to supply the airstream having the predefined values of the temperature and humidity to the AOI.

Also described herein is a rooftop air conditioning unit (RTU). The RTU comprises a first heat exchanger configured downstream of an absorber in a supply airstream, a second heat exchanger configured downstream of a desorber in a regeneration airstream, and a third heat exchanger configured in a return airstream, wherein the first heat exchanger is fluidically connected to the second heat exchanger and the third heat exchanger via a first vapor compression system.

In one or more embodiments, the RTU comprises a fourth heat exchanger configured upstream of the absorber in the supply airstream, and a fifth heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the fourth heat exchanger is fluidically connected to the fifth heat exchanger via a second vapor compression system, and wherein the absorber is fluidically connected to the absorber via a liquid desiccant system.

In one or more embodiments, the RTU comprises a fourth heat exchanger configured upstream of the absorber in the supply airstream, a fifth heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the first heat exchanger, and the fourth heat exchanger are fluidically connected to the second heat exchanger, the third heat exchanger, and the fifth heat exchanger via the first vapor compression system, and wherein the absorber is fluidically connected to the desorber via a liquid desiccant system.

In one or more embodiments, the RTU comprises a fourth heat exchanger configured upstream of the absorber in the supply airstream, and a fifth heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are fluidically connected to the first heat exchanger, and the fourth heat exchanger via the first vapor compression system, and wherein the absorber is fluidically connected to the desorber via a liquid desiccant system.

In one or more embodiments, the RTU is configured to operate one or more of the heat exchangers associated with the system as a condenser and/or an evaporator to adjust the temperature and humidity of the supply airstream at predefined values.

In one or more embodiments, when the supply airstream downstream of the absorber is to be cooled to provide the airstream of the predefined values, the first heat exchanger is operated as the evaporator, and the second heat exchanger and/or the third heat exchanger are operated as the condenser to reject heat of the supply airstream into the regeneration airstream and/or the return airstream.

In one or more embodiments, when the supply airstream downstream of the absorber is to be heated to provide the airstream of the predefined values, the first heat exchanger is operated as the condenser, and the second heat exchanger and/or the third heat exchanger are operated as the evaporator to supply heat from the regeneration airstream and/or the return airstream into the supply airstream.

In one or more embodiments, when the supply airstream downstream of the absorber is to be cooled to provide the airstream of the predefined values, the first heat exchanger and the fourth heat exchanger are operated as the evaporator, and one or more of the second heat exchanger, the third heat exchanger, and the fifth heat exchanger are operated as the condenser to reject heat of the supply airstream into the regeneration airstream and/or the return airstream.

In one or more embodiments, when the supply airstream downstream of the absorber is to be heated to provide the airstream of the predefined values downstream of the absorber, the first heat exchanger, and the fifth heat exchanger are operated as the condenser, and one or more of the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are operated as the evaporator to supply heat from the regeneration airstream and/or the return airstream into the supply airstream.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, features, and techniques of the invention will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the subject disclosure of this invention and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the subject disclosure and, together with the description, serve to explain the principles of the subject disclosure.

In the drawings, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

FIG. 1A illustrates an exemplary representation of a first embodiment of rooftop air conditioning unit (RTU) which is capable of handling outside air or ventilation at an area of interest or space in accordance with one or more embodiments of the disclosure.

FIG. 1B illustrates an exemplary psychrometric chart depicting the temperature and humidity of air in the supply airstream, regeneration airstream, and return airstream in the RTU of FIG. 1A.

FIG. 2A illustrates an exemplary representation of a second embodiment of an RTU operating in a first mode in accordance with one or more embodiments of the disclosure.

FIG. 2B illustrates an exemplary psychrometric chart depicting the temperature and humidity of air in the supply airstream, regeneration airstream, and return airstream in the RTU of FIG. 2A.

FIG. 2C illustrates an exemplary representation of the second embodiment of the RTU operating in a second mode in accordance with one or more embodiments of the disclosure.

FIG. 2D illustrates an exemplary psychrometric chart depicting the temperature and humidity of air in the supply airstream, regeneration airstream, and return airstream in the RTU of FIG. 2C

FIG. 3A illustrates an exemplary representation of a third embodiment of an RTU in accordance with one or more embodiments of the disclosure.

FIG. 3B illustrates an exemplary psychrometric chart depicting the temperature and humidity of air in the supply airstream, regeneration airstream, and return airstream in the RTU of FIG. 3A.

FIG. 4A illustrates an exemplary representation of a fourth embodiment of an RTU in accordance with one or more embodiments of the disclosure.

FIG. 4B illustrates an exemplary psychrometric chart depicting the temperature and humidity of air in the supply airstream, regeneration airstream, and return airstream in the RTU of FIG. 4A.

FIG. 5 illustrates an exemplary block diagram of the liquid desiccant-based outdoor air system.

DETAILED DESCRIPTION

The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject disclosure as defined by the appended claims.

Various terms are used herein. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the subject disclosure, the components of this invention. described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower,” “first”, “second” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the RTU, liquid desiccant system, absorber, desorber, heat exchangers, vapor compression system, and corresponding components, described herein may be oriented in any desired direction.

Existing rooftop air conditioning unit (RTU) includes a supply airstream, a regeneration airstream, and a return airstream. The RTU may involve a liquid desiccant system to condition the outside and provide conditioned supply airstream at an area of interest or space. When humidification and cooling are required to condition the outdoor air to neutral conditions before supplying to the space where the RTU is installed, ambient or outside air is allowed to enter into the system from outdoors and is cooled down to a lower temperature and saturated state at an evaporator part of a vapor compression system installed in the supply airstream. The cooled supply airstream is then supplied through and dehumidified at a contact media device (absorber or dehumidifier) associated with a liquid desiccant system where a concentrated solution of liquid desiccant is sprayed or blown across the supply airstream. The absorber or media device is installed downstream of the evaporator part in the supply airstream, in a process that decreases the air dew point and increases its dry bulb temperature. However, at this point of the process, the air downstream of the absorber or media device may either be warmer or colder than a user-defined range or neutral range making it inconvenient for the users in the space. There is therefore a need to improve the existing RTU to provide a user-defined range or a neutral range of 70° F. to 75° F. to the space.

This invention provides a simple, improved, efficient, and cost-effective liquid rooftop air conditioning unit (RTU). The RTU conditions the supply airstream downstream of the absorber in a comfortable or neutral range by implementing additional heat exchangers downstream of the absorber and the desorber, and/or in the return airstream. The additional heat exchangers may be a part of the main vapor compression system of the RTU or may be a part of an additional vapor compression system (in addition to the main vapor compression system). The heat exchangers may be operated as an evaporator or a condenser to further condition the supply airstream, thereby efficiently and cost-effectively controlling the temperature and humidity of the supply airstream to a user-defined range or neutral range. The RTU is capable of handling outside air to provide ventilation at the AOI or space.

Referring to FIG. 1A, a first embodiment of the rooftop air conditioning unit “RTU” 100 is disclosed. The RTU 100 may include an absorber 102 (also referred to as dehumidifier 102, herein) configured in a supply airstream (SA), and a desorber 104 (also referred to as regenerator 104, herein) configured in a regeneration airstream (RA). The desorber 104 may be fluidically connected to the absorber 102 via a liquid desiccant system 106. The RTU 100 may further include a first heat exchanger 108 configured upstream of the absorber 102 in the supply airstream SA, and a second heat exchanger 110 configured upstream of the desorber 104 in the regeneration airstream RA. The first heat exchanger 108 may be fluidically connected to the second heat exchanger 110 via a vapor compression system 112. In addition, the RTU 100 may include a third heat exchanger 114 configured between the vapor compression system 112 and the liquid desiccant system 106. The heat exchangers 108, 110, 114 are operable to control the temperature and humidity of the supply airstream downstream of the absorber 102 or to be supplied to an area of interest (AOI) or space to predefined or user-defined values. In one or more embodiments, the predefined value of the temperature of the airstream to be supplied to the AOI or space is in a neutral or comfort range of 70° F. to 75° F. but is not limited to the like.

The heat exchangers 108, 110, 114 of the RTU 100 may be operated as an evaporator and/or a condenser to control the temperature and humidity of the supply airstream and also facilitating controlling the mass transfer potential between the desiccant and the airstream at the absorber 102 and the desorber 104.

In one or more embodiments, when the supply airstream downstream of the absorber 102 is to be cooled to provide the supply airstream of the predefined values to the AOI or space, the first heat exchanger 108 and/or the third heat exchanger 114 may be operated as the evaporator, and the second heat exchanger 110 may be operated as the condenser to reject heat of the supply airstream into the regeneration airstream.

In the liquid desiccant system 106, the desiccant circulates between the absorber 102 and the desorber 104. In the absorber 102 (humidifier), a concentrated solution of the desiccant is distributed over a contact media device while ambient air or outdoor air is blown across the desiccant stream. The desiccant stream absorbs moisture from the air and is simultaneously cooled down. The results of this process are the cool dry air downstream of the absorber 102 and the diluted desiccant solution. In the desorber 104 (regenerator), the diluted desiccant solution from the absorber 102 is distributed over a contact media device, and the ambient air is blown across the desiccant solution stream. Accordingly, some moisture/water is taken away from the diluted desiccant solution by the ambient air while the desiccant is heated. The resulting concentrated desiccant solution is then collected, and hot humid air is rejected to the ambient. Further, the collected concentrated desiccant solution is circulated back to the absorber 102.

In one or more embodiments, the RTU 100 may comprise one or more passive heat transfer systems such as but not limited to enthalpy wheels and/or recirculated fluid loop fluidically configured between the supply air stream and the return air stream, and/or between the supply airstream and the regeneration airstream of the RTU 100 to facilitate controlling the temperature of the supply air stream to be supplied to the AOI or space to user-defined values or neutral condition.

Referring to FIG. 1B, a psychrometric chart of the processes involved in the RTU 100 when the supply airstream is to be cooled to provide the user-defined or neutral supply airstream at the AOI or space is disclosed. The RTU 100 takes in ambient/outside air OA1 or SA1 in the supply airstream, whose temperature may be lowered by additional energy recovery devices such as an enthalpy wheel and the like (not shown) that may be installed upstream of the first heat exchanger 108 to provide SA2, however, the humidity of the SA1 and SA2 remains the same. The first heat exchanger 108 acting as an evaporator subsequently cools the SA2 upstream and provides cool SA3 to the absorber 102 where the air can lose moisture from SA2 to SA3. The cool SA3 is then passed through the absorber 102 where the SA3 is dehumidified in a process where a concentrated solution of the desiccant is distributed over while SA3 is blown across the desiccant stream. The desiccant stream absorbs moisture from the SA3, which is simultaneously cooled down to keep the SA4 downstream of the absorber 102 dehumidified and in the neutral range or user-defined range. The dehumidified SA4 downstream of the absorber 102 is further cooled at the third heat exchanger 114 that is acting as an evaporator to supply cool and dehumidified SA5 to the AOI or space where the RTU 100 is employed. The heat rejected by the first heat exchanger 108 and/or the third heat exchanger 114 while cooling the air in the supply airstream is rejected into the regeneration airstream via the second heat exchanger 110 connected to the first heat exchanger 108 and the third heat exchanger 114.

The RTU 100 also takes in ambient/outside air OA1 in the regeneration airstream. The second heat exchanger 110 acting as a condenser subsequently heats the OA1 upstream of the second heat exchanger 110 and provides heated OA2 to the desorber 104, however, the humidity of the OA1 and OA2 remains the same. Further, the OA2 is then passed through the desorber 104 where the OA2 is further heated by the desiccant received from the absorber 102 to provide heated OA3. In the desorber 104, the OA2 is blown across the desiccant solution stream received from the absorber 102. Accordingly, some moisture/water is taken away from the diluted desiccant solution by the OA2 while the desiccant is heated. The resulting concentrated desiccant solution is then collected, and hot humid air OA3 downstream of the desorber 104 is rejected to the ambient.

Further, the concentrated desiccant solution collected from the desorber 104 is further circulated back to the absorber 102. The RTU 100 conditions the desiccant with the interchange heat exchanger by allowing hot desiccant downstream of the desorber 104 to cool down before entering the absorber 102, thereby improving water mass transfer from the air to the desiccant. Further, the interchange heat exchanger allows cold desiccant downstream of the absorber 102 to heat up before it enters the desorber 104, thereby improving water mass transfer from the desiccant to the air.

Referring to FIGS. 2A and 2C, a second embodiment of the RTU 200 is disclosed. The RTU 200 may include an absorber 102 (also referred to as dehumidifier 102, herein) configured in a supply airstream (SA), and a desorber 104 (also referred to as regenerator 104, herein) configured in a regeneration airstream (RA). The desorber 104 may be fluidically connected to the absorber 102 via a liquid desiccant system 106. The RTU 200 may further include a first heat exchanger 202 configured downstream of the absorber 102 in the supply airstream SA, a second heat exchanger 204 configured upstream of the desorber 104 in the regeneration airstream RA, a third heat exchanger 206 configured in a return airstream. The first heat exchanger 202 may be fluidically connected to the second heat exchanger 204 and the third heat exchanger 206 via a first vapor compression system 212. Further, the RTU 200 may include a fourth heat exchanger 208 configured upstream of the absorber 102 in the supply airstream, and a fifth heat exchanger 210 configured upstream of the desorber 104 in the regeneration airstream. The fourth heat exchanger 208 may be fluidically connected to the fifth heat exchanger 210 via a second vapor compression system 214.

The heat exchangers 202 to 210 and the vapor compression systems 212, 214 are operable to adjust or control the temperature and humidity of the supply airstream supplied to the AOI or space to predefined or user-defined values. In one or more embodiments, the predefined value of the temperature of the airstream supplied to the AOI or space is in a neutral or comfort range of 70° F. to 75° F. but is not limited to the like.

In one or more embodiments, the RTU 200 may comprise one or more passive heat transfer systems 216, 218, 220 such as but not limited to enthalpy wheels and/or recirculated fluid loop fluidically configured between the supply air stream and the return air stream, and/or between the supply airstream and the regeneration airstream of the RTU 200 to facilitate controlling the temperature of the air to user-defined values or neutral condition.

The heat exchangers 202 to 210 of the RTU 200 may be operated as an evaporator and/or a condenser to control the temperature and humidity of the supply airstream and also facilitating controlling the mass transfer potential between the desiccant and the airstream at the absorber 102 and the desorber 104.

In one or more embodiments, as shown in FIG. 2A, when the supply airstream downstream of the absorber 102 is to be cooled to provide the airstream of the predefined values to the AOI or space, the RTU 200 may be operated in the first mode where the first heat exchanger 202, and the fourth heat exchanger 208 may be operated as the evaporator, and the second heat exchanger 204, the third heat exchanger 206, and/or the fifth heat exchanger 210 may be operated as the condenser to reject heat of the supply airstream into the regeneration airstream and/or the return airstream.

Referring to FIG. 2B, a psychrometric chart of the processes involved in the RTU 200 operating in the first mode when the supply airstream is to be cooled to provide the user-defined or neutral supply airstream to the AOI or space is disclosed. The RTU 200 takes in ambient/outside air OA1 or SA1 in the supply airstream. The heat dissipating device 216 may be operated to slightly cool the SA1 to SA2 by exchanging heat between the supply airstream and the return airstream, however, the humidity of the SA1 and SA2 remains the same. The fourth heat exchanger 208 acting as an evaporator subsequently cools the SA2 downstream of the heat dissipating device 216 and provides cool SA3 to the absorber 102 where the air loses moisture from SA2 to SA3. The cool SA3 is then passed through the absorber 102 where the SA3 is dehumidified in a process where a concentrated solution of the desiccant is distributed over while SA3 is blown across the desiccant stream. The desiccant stream absorbs moisture from the SA3, which is simultaneously cooled down to keep the SA4 downstream of the absorber 102 cool and dehumidified in the neutral range or user-defined range. The dehumidified SA4 downstream of the absorber 102 is further cooled at the first heat exchanger 202 that is acting as an evaporator to supply cool and dehumidified SA5, which may be further conditioned by the heat dissipating devices 218, 220 to provide cool and dehumidified supply airstream to AOI or space where the RTU 200 is employed, however, the heat dissipating devices 218, 220 may also be kept inactive based on the temperature of the air coming out of the first heat exchanger 202. The heat rejected by the first heat exchanger 202 while cooling the air in the supply airstream is rejected into the regeneration airstream and/or the return airstream via the second heat exchanger 204 and the third heat exchanger 206 connected to the first heat exchanger 202 via the first vapor compression system 212. Further, the heat rejected by the fourth heat exchanger 208 while cooling the air in the supply airstream is rejected into the regeneration airstream via the fifth heat exchanger 208210 connected to the fourth heat exchanger 208 via the second vapor compression system 214.

The RTU 200 also takes in ambient/outside air OA1 in the regeneration airstream. The fifth heat exchanger 210 acting as a condenser subsequently heats the OA1 upstream of the fourth heat exchanger 208 and provides heated OA2 to the desorber 104, however, the humidity of the OA1 and OA2 remains the same. Further, the OA2 is then passed through the desorber 104 where the OA2 is further heated by the desiccant received from the absorber 102 to provide heated OA3. In the desorber 104, the OA2 is blown across the desiccant solution stream received from the absorber 102. Accordingly, some moisture/water is taken away from the diluted desiccant solution by the OA2 while the desiccant is heated. The resulting concentrated desiccant solution is then collected, and hot humid air OA3 downstream of the desorber 104 is supplied to the second heat exchanger 204 that is acting as the condenser to further heat the OA4 which is rejected to the ambient. Furthermore, the heat rejected by the supply airstream may be transferred to the return airstream via the heat dissipating device 220 to heat the return airstream from RA1 to RA3, which may be further heated at the third heat exchanger 206 that is acting as the condenser.

In one or more embodiments, as shown in FIG. 2C, when the supply airstream downstream of the absorber 102 is to be heated to provide the airstream of the predefined values at the AOI or space, the RTU 200 may be operated in the second mode where the first heat exchanger 202, and the fifth heat exchanger 210 may be operated as the condenser, and the second heat exchanger 204, the third heat exchanger 206, and/or the fourth heat exchanger 208 may be operated as the evaporator to supply heat from the regeneration airstream and/or the return airstream into the supply airstream.

Referring to FIG. 2D, a psychrometric chart of the processes involved in the RTU 200 operating in the second mode when the supply airstream downstream of the absorber 102 is to be heated to provide the user-defined or neutral supply airstream to the AOI or space is disclosed. The RTU 200 takes in ambient/outside air OA1 or SA1 in the supply airstream. The fourth heat exchanger 208 acting as an evaporator subsequently cools the SA1 and provides cool SA2 to the absorber 102, however, the humidity of the SA1 and SA2 remains the same. The cool SA2 is passed through the absorber 102 where the SA2 is dehumidified in a process where a concentrated solution of the desiccant is distributed over while SA2 is blown across the desiccant stream. The desiccant stream absorbs moisture from the SA2, which is simultaneously cooled down to keep the SA3 downstream of the absorber 102 cool and dehumidified. The dehumidified SA3 downstream of the absorber 102 may be further heated at the first heat exchanger 202 (that is acting as a condenser in mode 2) based on the neutral range or user-defined values of supply airstream to be supplied at the AOI, to supply conditioned and dehumidified SA4 downstream of the first heat exchanger 202. The SA4 may be further conditioned by the heat dissipating devices 218, 220 to supply conditioned and dehumidified supply airstream SA6 at AOI or space where the RTU 200 is employed. The heat rejected by the fourth heat exchanger 208 while cooling the air in the supply airstream is rejected into the regeneration airstream via the fifth heat exchanger 210 connected to the fourth heat exchanger 208 via the second vapor compression system 214. Further, the heat received by the first heat exchanger 202 for heating the air downstream of the absorber 102 in the supply airstream is received from the second heat exchanger 204, and/or the third heat exchanger 206 connected to the first heat exchanger 202 via the first vapor compression system 212. Furthermore, in the second mode, heat may be transferred to the supply airstream from the return airstream or the regeneration airstream via the heat dissipating devices 218, 220 to heat the supply return airstream downstream of the first heat exchanger 202, thereby heating the return airstream from RA1 to RA2.

Referring to FIG. 3A, a third embodiment of the RTU 300 is disclosed. The RTU 300 may include an absorber 102 (also referred to as dehumidifier 102, herein) configured in a supply airstream (SA), and a desorber 104 (also referred to as regenerator 104, herein) configured in a regeneration airstream (RA). The desorber 104 may be fluidically connected to the absorber 102 via a liquid desiccant system 106. The RTU 300 may further include a first heat exchanger 302 configured downstream of the absorber 102 in the supply airstream SA, a second heat exchanger 304 configured upstream of the desorber 104 in the regeneration airstream RA, a third heat exchanger 306 configured in a return airstream. Further, the RTU 300 may include a fourth heat exchanger 308 configured upstream of the absorber 102 in the supply airstream, and a fifth heat exchanger 310 configured upstream of the desorber 104 in the regeneration airstream. The first heat exchanger 302, and the fourth heat exchanger 308 may be fluidically connected to the second heat exchanger 304, the third heat exchanger 306, and the fifth heat exchanger 310 via the first vapor compression system 312, without the requirement of additional vapor compression system as in FIGS. 2A and 2C.

The heat exchangers 302 to 310 are operable to control the temperature and humidity of the supply airstream to predefined or user-defined values. In one or more embodiments, the predefined value of the temperature of the airstream supplied to the AOI or space is in a neutral or comfort range of 70° F. to 75° F. but is not limited to the like.

In one or more embodiments, the RTU 300 may comprise one or more passive heat transfer systems 316, 318, 320 such as but not limited to enthalpy wheels and/or recirculated fluid loop fluidically configured between the supply air stream and the return air stream, and/or between the supply airstream and the regeneration airstream of the RTU 300 to facilitate controlling the temperature of the air to user-defined values or neutral condition.

The heat exchangers 302 to 310 of the RTU 300 may be operated as an evaporator and/or a condenser to control the temperature and humidity of the supply airstream to be supplied to the AOI or space and also facilitate controlling the mass transfer potential between the desiccant and the airstream at the absorber 102 and the desorber 104.

In one or more embodiments, when the supply airstream is to be cooled to provide the airstream of the predefined values to the AOI or space, the first heat exchanger 302 and the fourth heat exchanger 308 may be operated as the evaporator, and one or more of the second heat exchanger 304, the third heat exchanger 306, and the fifth heat exchanger 310 may be operated as the condenser to reject heat of the supply airstream into the regeneration airstream and/or the return airstream.

Referring to FIG. 3B, a psychrometric chart of the processes involved in the RTU 300 operating in the first mode when the supply airstream is to be cooled to provide the user-defined or neutral supply airstream to the AOI or space is disclosed. The RTU 300 takes in ambient/outside air OA1 or SA1 in the supply airstream. The heat dissipating device 316 may be operated to slightly cool the SA1 to SA2 by exchanging heat between the supply airstream and the return airstream, however, the humidity of the SA1 and SA2 remains the same. The fourth heat exchanger 308 acting as an evaporator subsequently cools the SA2 downstream of the heat dissipating device 316 and provides cool SA3 to the absorber 102. The cool SA3 is then passed through the absorber 102 where the SA3 is dehumidified in a process where a concentrated solution of the desiccant is sprayed over while SA3 is blown across the desiccant stream. The desiccant stream absorbs moisture from the SA3, which is simultaneously cooled down to keep the SA4 downstream of the absorber 102 cool and dehumidified in the neutral range or user-defined range. The dehumidified SA4 downstream of the absorber 102 is further cooled at the first heat exchanger 302 that is acting as an evaporator to supply cool and dehumidified SA5, which may be further conditioned by the heat dissipating devices 318, 320 to provide cool and dehumidified supply airstream to AOI or space where the RTU 300 is employed, however, the heat dissipating devices 318, 320 may also be kept inactive. The heat rejected by the first heat exchanger 302 and/or the fourth heat exchanger 308 while cooling the air in the supply airstream is rejected into the regeneration airstream and/or the return airstream via the second heat exchanger 304, the third heat exchanger 306 and the fifth heat exchanger 310 connected to the first heat exchanger 302 and fourth heat exchanger 308 via the first vapor compression system 312.

The RTU 300 also takes in ambient/outside air OA1 in the regeneration airstream. The fifth heat exchanger 310 acting as a condenser subsequently heats the OA1 upstream of the fifth heat exchanger 310 and provides heated OA2 to the desorber 104, however, the humidity of the OA1 and OA2 remains the same. Further, the OA2 is then passed through the desorber 104 where the OA2 is further heated by the desiccant received from the absorber 102 to provide heated OA3. In the desorber 104, the OA2 is blown across the desiccant solution stream received from the absorber 102. Accordingly, some moisture/water is taken away from the diluted desiccant solution by the OA2 while the desiccant is heated. The resulting concentrated desiccant solution is then collected, and hot humid air OA3 downstream of the desorber 104 is supplied to the second heat exchanger 304 that is acting as the condenser to further heat the OA4 which is rejected to the ambient. Furthermore, the heat rejected by the supply airstream may be transferred to the return airstream via the heat dissipating device 320 to heat the return airstream from RA1 to RA3, which may be further heated at the third heat exchanger 306 that is acting as the condenser.

Referring to FIG. 4A, a fourth embodiment of the RTU 400 is disclosed. The RTU 400 may include an absorber 102 (also referred to as dehumidifier 102, herein) configured in a supply airstream (SA), and a desorber 104 (also referred to as regenerator 104, herein) configured in a regeneration airstream (RA). The desorber 104 may be fluidically connected to the absorber 102 via a liquid desiccant system 106. The RTU 400 may further include a first heat exchanger 402 configured downstream of the absorber 102 in the supply airstream SA, a second heat exchanger 404 configured upstream of the desorber 104 in the regeneration airstream RA, a third heat exchanger 406 configured in a return airstream. The first heat exchanger 402 may be fluidically connected to the second heat exchanger 404 and the third heat exchanger 406 via a vapor compression system 412. Further, the RTU 400 may include a fourth heat exchanger 408 configured upstream of the absorber 102 in the supply airstream, and a fifth heat exchanger 410 configured upstream of the desorber 104 in the regeneration airstream. The second heat exchanger 304, the third heat exchanger 306, and the fourth heat exchanger 508 may be fluidically connected to the first heat exchanger 402, and the fifth heat exchanger 510 via the vapor compression system 412, without the requirement of an additional vapor compression system as in FIGS. 2A and 2B.

The heat exchangers 402 to 410 are operable to control the temperature and humidity of the supply airstream to predefined or user-defined values. In one or more embodiments, the predefined value of the temperature of the airstream supplied to the AOI or space is in a neutral or comfort range of 70° F. to 75° F. but is not limited to the like.

In one or more embodiments, the RTU 400 may comprise one or more passive heat transfer systems 416, 418, 420 such as but not limited to enthalpy wheels and/or recirculated fluid loop fluidically configured between the supply air stream and the return air stream, and/or between the supply airstream and the regeneration airstream of the RTU 400 to facilitate controlling the temperature of the air to user-defined values or neutral condition.

The heat exchangers 402 to 410 of the RTU 400 may be operated as an evaporator and/or a condenser to control the temperature and humidity of the supply airstream to be supplied to the AOI or space and also facilitate controlling the mass transfer potential between the desiccant and the airstream at the absorber 102 and the desorber 104.

In one or more embodiments, when the supply airstream downstream of the absorber 102 is to be heated to provide the airstream of the predefined values to the AOI or space, the first heat exchanger 402 and the fifth heat exchanger 410 may be operated as the condenser, and one or more of the second heat exchanger 404, the third heat exchanger 406, and the fourth heat exchanger 408 may be operated as the evaporator to supply heat from the regeneration airstream and/or the return airstream into the supply airstream downstream of the absorber 102.

Referring to FIG. 4B, a psychrometric chart of the processes involved in the RTU 400 when the supply airstream downstream of the absorber is to be heated to provide the user-defined or neutral supply airstream to the AOI or space is disclosed. The RTU 400 takes in ambient/outside air OA1 or SA1 in the supply airstream. The fourth heat exchanger 408 acting as an evaporator subsequently cools the SA1 and provides slightly cooled SA2 to the absorber 102, however, the humidity of the SA1 and SA2 remains the same. The cool SA2 is passed through the absorber 102 where the SA2 is dehumidified in a process where a concentrated solution of the desiccant is distributed over while SA2 is blown across the desiccant stream. The desiccant stream absorbs moisture from the SA2, which is simultaneously cooled down to keep the SA3 downstream of the absorber 102 cool and dehumidified. The dehumidified SA3 downstream of the absorber 102 may be further heated at the first heat exchanger 402 (that is acting as a condenser based on the neutral range or user-defined values of supply airstream to be supplied at the AOI, to supply conditioned and dehumidified SA4 downstream of the first heat exchanger 202 based on the airstream to be supplied to the AOI or space. The SA4 may be further conditioned by the heat dissipating devices 418, 420 to supply conditioned and dehumidified supply airstream SA6 at AOI or space where the RTU 400 is employed. The heat rejected by the fourth heat exchanger 408 while cooling the air in the supply airstream is rejected into the regeneration airstream via the fifth heat exchanger 410 connected to the fourth heat exchanger 408 via the vapor compression system 412. Further, the heat received by the first heat exchanger 402 for heating the air downstream of the absorber 102 in the supply airstream is received from the second heat exchanger 204, and/or the third heat exchanger 206 and/or the fourth heat exchanger 408 connected to the first heat exchanger 402 via the vapor compression system 412. Furthermore, heat may be transferred to the supply airstream from the return airstream or the regeneration airstream via the heat dissipating devices 418, 420 to heat the supply return airstream downstream of the first heat exchanger 402, thereby heating the return airstream from RA1 to RA2, which may be further cooled in the return airstream by the third heat exchanger that acting as the evaporator to provide RA3.

In one or more embodiments, the RTU 100, 200, 300, and 400 may be adapted to be configured or installed at an area of interest (AOI) to supply the air having the predefined values of the temperature and humidity at the AOI, and further, receive the return airstream from the AOI, thereby handling outside air and providing ventilation at the AOI. Referring to FIG. 5, the RTU 100, 200, 300, and 400 may further comprise a controller 502 that may be configured to receive a set of instructions pertaining to the predefined values of the airstream to be supplied at the AOI. Users at the AOI or remote location may select the predefined values of the temperature and humidity of the air to be supplied at the AOI. Accordingly, the controller 502 can operate the heat exchangers associated with the RTU 100, 200, 300, and 400 as an evaporator and/or condenser to supply the airstream having the predefined values.

The RTU 100, 200, 300, and 400 generally have two separate functions. The conditioning side or supply airstream side of the RTU 100, 200, 300, and 400 provides conditioning of air to the user-defined conditions, which may be set using thermostats or humidistats. The regeneration side of the RTU 100, 200, 300, and 400 provides a reconditioning function of the liquid desiccant so that the desiccant can be reused on the conditioning side. The controller 502 is used to properly balance the liquid desiccant between the two sides as conditions necessitate and that excess heat and moisture are properly dealt with without leading to over-concentrating or under-concentrating the desiccant.

The RTU 100, 200, 300, and 400 may include one or more humidity sensors 504 and one or more temperature sensors 506 installed in the supply airstream, regeneration airstream, and return airstream to monitor the temperature and humidity of air throughout the RTU 100. Further, temperature sensors 506 and flow sensors 508 may also be installed in the liquid desiccant system 106 to monitor temperature and pressure or flow rate circulated between the absorber 102 and desorber 104. The controller 502 may include a processor coupled to a memory storing instructions executable by the processor, which enables the controller 502 to receive the temperature, pressure, and humidity data from the corresponding sensors installed in the RTU 100. The controller 502 also receives user-defined conditions of air to be supplied at the AOI, which may be set using thermostats or humidistats 510. Accordingly, the controller 502 may actuate the one or more components associated with the RTU 100, 200, 300, and 400 to adjust the temperature of the desiccant, thereby adjusting the temperature and humidity of the supply airstream to user-defined values or a neutral range of 70° F. to 75° F.

Thus, the RTU efficiently and cost-effectively controls the temperature and humidity of the supply airstream to a user-defined range or neutral range and also controls ventilation at the AOI

While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined by the appended claims. Modifications may be made to adopt a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention includes all embodiments falling within the scope of the invention as defined by the appended claims.

In interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.

Claims

1. A rooftop air conditioning unit (RTU) comprising: an absorber configured in a supply airstream;a desorber configured in a regeneration airstream, wherein the desorber is fluidically connected to the absorber via a liquid desiccant system;a first heat exchanger configured upstream of the absorber in the supply airstream;a second heat exchanger configured upstream of the desorber in the regeneration airstream; anda third heat exchanger configured downstream of the absorber in the supply airstream, wherein the first heat exchanger and the third heat exchanger are fluidically connected to the second heat exchanger via a vapor compression system.

2. The RTU of claim 1, wherein the RTU is configured to operate one or more of the first heat exchanger, the second first heat exchanger, and the third heat exchanger with the RTU as a condenser and/or an evaporator to adjust temperature and humidity of the supply airstream, downstream of the absorber, at predefined values.

3. The RTU of claim 2, when the supply airstream is to be cooled to provide the airstream of the predefined values downstream of the absorber, the first heat exchanger and/or the third heat exchanger is operated as the evaporator, and the second heat exchanger is operated as the condenser to reject heat of the supply airstream into the regeneration airstream.

4. The RTU of claim 1, wherein the RTU comprises one or more passive heat transfer systems fluidically configured between the supply air stream and the return air stream, and/or between the supply airstream and the regeneration airstream.

5. The RTU of claim 4, wherein the one or more passive heat transfer systems comprises enthalpy wheels and/or recirculated fluid loop.

6. The RTU of claim 1, wherein the RTU is adapted to be configured at an area of interest (AOI) to supply the airstream having the predefined values of the temperature and humidity at the AOI, and further receive the return airstream from the AOI.

7. The RTU of claim 6, wherein the RTU comprises a controller that is configured to: receive a set of instructions pertaining to the predefined values of the airstream to be supplied at the AOI; andcontrol operation of one or more of the heat exchangers associated with the system to supply the airstream having the predefined values of the temperature and humidity to the AOI.

8. A rooftop air conditioning unit (RTU) comprising: a first heat exchanger configured downstream of an absorber in a supply airstream,a second heat exchanger configured downstream of a desorber in a regeneration airstream; anda third heat exchanger configured in a return airstream, wherein the first heat exchanger is fluidically connected to the second heat exchanger and the third heat exchanger via a first vapor compression system.

9. The RTU of claim 8, wherein the RTU comprises: a fourth heat exchanger configured upstream of the absorber in the supply airstream; anda fifth heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the fourth heat exchanger is fluidically connected to the fifth heat exchanger via a second vapor compression system, andwherein the absorber is fluidically connected to the absorber via a liquid desiccant system.

10. The RTU of claim 8, wherein the RTU comprises: a fourth heat exchanger configured upstream of the absorber in the supply airstream; anda fifth heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the first heat exchanger, and the fourth heat exchanger are fluidically connected to the second heat exchanger, the third heat exchanger, and the fifth heat exchanger via the first vapor compression system, andwherein the absorber is fluidically connected to the desorber via a liquid desiccant system.

11. The RTU of claim 8, wherein the RTU comprises: a fourth heat exchanger configured upstream of the absorber in the supply airstream; anda fifth heat exchanger configured upstream of the desorber in the regeneration airstream, wherein the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are fluidically connected to the first heat exchanger, and the fourth heat exchanger via the first vapor compression system, andwherein the absorber is fluidically connected to the desorber via a liquid desiccant system.

12. The RTU of claim 8, wherein the RTU is configured to operate one or more of the heat exchangers associated with the RTU as a condenser and/or an evaporator to adjust the temperature and humidity of the supply airstream at predefined values.

13. The RTU of claim 8, wherein when the supply airstream downstream of the absorber is to be cooled to provide the airstream of the predefined values, the first heat exchanger is operated as an evaporator, and the second heat exchanger and/or the third heat exchanger are operated as a condenser to reject heat of the supply airstream into the regeneration airstream and/or the return airstream.

14. The RTU of claim 8, wherein when the supply airstream downstream of the absorber is to be heated to provide the airstream of the predefined values, the first heat exchanger is operated as a condenser, and the second heat exchanger and/or the third heat exchanger are operated as an evaporator to supply heat from the regeneration airstream and/or the return airstream into the supply airstream.

15. The RTU of claim 9, wherein when the supply airstream downstream of the absorber is to be cooled to provide the airstream of the predefined values, the first heat exchanger and the fourth heat exchanger are operated as an evaporator, and one or more of the second heat exchanger, the third heat exchanger, and the fifth heat exchanger are operated as a condenser to reject heat of the supply airstream into the regeneration airstream and/or the return airstream.

16. The RTU of claim 9, wherein when the supply airstream downstream of the absorber is to be heated to provide the airstream of the predefined values downstream of the absorber, the first heat exchanger, and the fifth heat exchanger are operated as a condenser, and one or more of the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are operated as an evaporator to supply heat from the regeneration airstream and/or the return airstream into the supply airstream.

17. The RTU of claim 8, wherein the RTU comprises one or more passive heat transfer systems fluidically configured between the supply air stream and the return air stream, and/or between the supply airstream and the regeneration airstream.

18. The RTU of claim 17, wherein the one or more passive heat transfer systems comprises enthalpy wheels and/or recirculated fluid loop.

19. The RTU of claim 8, wherein the RTU is adapted to be configured at an area of interest (AOI) to supply the airstream having predefined values of the temperature and humidity at the AOI, and further receive the return airstream from the AOI.

20. The RTU of claim 19, wherein the RTU comprises a controller that is configured to: receive a set of instructions pertaining to the predefined values of the airstream to be supplied at the AOI; andcontrol operation of one or more of the heat exchangers associated with the system to supply the airstream having the predefined values of the temperature and humidity to the AOI.