Heat pump equipment

Abstract
Heat pump equipment comprising at least three heat exchangers, one of which is intended to be located in an enclosed region and the other two of which are intended to be located outside the enclosed region. Each heat exchanger has a delta connection end connected in heat-exchange fluid communication with a delta arrangement. The delta connection end of each heat exchanger is connected to both of the delta connection ends of the other two heat exchangers via the delta arrangement. There are three fluid-expansion devices, one between the two connections of each pair of adjacent connections of the heat exchangers to the delta arrangement.The present invention extends to heat pump equipment comprising at least three heat exchangers connected in a heat-exchange fluid circuit, one of which heat exchangers is intended to be located in an enclosed region and another of which is intended to be located outside the enclosed region. A third one of the heat exchangers is arranged so that air which flows through an aperture in a wall which forms a boundary of the enclosed region passes over the said third heat exchanger.
Description




TECHNICAL FIELD




The present invention relates to heat pump equipment.




BACKGROUND ART




In previously proposed heat pump equipment, means have been provided to enable heat exchangers outside a building to be defrosted even while the equipment is being used to transfer heat from outside the building into its interior, in the form of more than one pressure drop and complex solenoid operated valve systems. This has made the equipment relatively expensive, and, because of its complexity, relatively difficult to diagnose any malfunction occurring within the equipment.




SUMMARY OF THE INVENTION




A first aspect of the present invention seeks to obviate this disadvantage.




Accordingly, a first aspect of the present invention is directed to heat pump equipment comprising at least three heat exchangers, one of which is intended to be located in an enclosed region and the other two of which are intended to be located outside the enclosed region, in which each heat exchanger has a delta connection end connected in heat-exchange fluid communication with a delta arrangement, such that the delta connection end of each heat exchanger is connected to both of the delta connection ends of the other two heat exchangers via the delta arrangement, in which arrangement there are three fluid-expansion devices, one between the two connections of each pair of adjacent connections of the heat exchangers to the delta arrangement.




Such equipment has the advantage that heat-exchange fluid can be directed to flow from the two outside heat exchangers to the inside heat exchanger, or alternatively from the inside heat exchanger to the two outside heat exchangers, and for defrosting of either one of the outside heat exchangers, fluid can be directed to flow from both that one of the outside heat exchangers and the inside heat exchanger to the other outside heat exchanger via the delta arrangement.




To achieve this, there is preferably one compressor connected to receive heat-exchange fluid from and to feed heat-exchange fluid to the heat exchangers via a valve arrangement.




The valve arrangement may comprise a valve for each heat exchanger. Each valve may be a four-way valve.




Equipment embodying this first aspect of the present invention may be easier to service than previously proposed equipment. Use of the gas phase to effect defrosting of the outside coils allows defrost rates to be unaffected by gravity especially defrost rates of each path of multiple path heat exchangers if these are used. This speeds defrosting by an even distribution of heat. The path length does not need to be reduced when one of the outside heat exchangers is defrosted. This increases the maximum performance in the event that a refrigerant with a glide is used.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a schematic of a first embodiment of the invention.





FIG. 2

is a schematic of a second embodiment of the invention.





FIG. 3

is a schematic of a third embodiment of the invention.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




An example of heat pump equipment embodying the first aspect of the present invention is illustrated in

FIG. 1

of the accompanying drawings which shows, diagrammatically, a fluid circuit of the equipment.




The heat exchange equipment


10


shown in

FIG. 1

comprises a compressor


12


having its fluid output connected via a four-way valve


14


to a heat-exchange coil


16


at one end thereof, the other end of which is connected to an apex


18


of a delta arrangement


20


. A second apex


22


of the delta arrangement


20


is connected to one end of a fluid exchange coil


24


, the other end of which is connected to the input end of the compressor


12


via a four-way valve


26


.




The output of the compressor


12


is also connected to one end of a heat-exchange coil


28


via a third four-way valve


30


, and the other end of the heat-exchange coil


28


is connected to a third apex


31


of the delta arrangement


20


.




There is a first expansion device


32


between the apices


18


and


22


of the delta arrangement, a second expansion device


34


between the apices


22


and


31


of the delta arrangement


20


, and a third expansion device


36


between the apices


18


and


31


of the delta arrangement


20


.




The heat-exchange coils


16


,


24


and


28


are provided with respective fans


38


,


40


and


42


. These are arranged to direct air to flow over their respective coils.




The heat-exchange coil


24


is located within an enclosed region


44


, whilst the coils


16


and


28


are located outside of the enclosed region


44


. A wall


46


of the region


44


creates an outside boundary between the enclosed region


44


and outside regions.




With the arrangement connected in this way, the compressor


12


drives hot gases through the valves


14


and


30


into the exterior heat-exchange coils


16


and


28


. As the hot gaseous heat-exchange fluid flow through the heat-exchange coils


16


and


28


, it is cooled by the outside air, and this cooling is assisted by the operation of the fans


38


and


42


to result in condensation of the heat-exchange fluid in those coils. The liquid heat-exchange fluid from the heat-exchange coil


16


passes to the apex


18


of the delta arrangement


20


through the expansion device


32


to the apex


22


and from thence to one end of the heat-exchange coil


24


. Likewise, the liquid heat-exchange fluid from the heat-exchange coil


28


flows from one end thereof to the apex


31


of the delta arrangement


20


, through the expansion device


34


to the apex


22


and again onwards to the heat-exchange coil


24


. Thus, it will be seen that liquid from the coils


16


and


28


meets at the apex


22


. Because there is substantially no differential pressure across the expansion device


36


in this condition of the heat pump equipment, substantially no fluid flows between the apices


18


and


31


of the delta arrangement


20


, so that in this particular condition of the heat pump equipment, it is as if there were no connection between those apices. At the heat-exchange coil


24


, the liquid is warmed by the air within the enclosed region


44


, and this exchange is assisted by the fan


40


. It results in the cooling of the air in the enclosed region


44


. After flowing through the heat-exchange coil


24


, the heat-exchange fluid returns back to the compressor


12


via the four-way valve


26


.




The valves


14


,


26


, and


30


may be switched so that the output of the compressor


12


is now connected via the four-way valve


26


directly to the heat-exchange coil


24


. The hot gaseous heat-exchange fluid is cooled in this coil


24


by the air within the enclosed region


44


, which heat-exchange is assisted by the fan


40


, so that the air in the enclosed region


44


is heated. The heat-exchange fluid continues from the coil


24


to the apex


22


of the delta arrangement


20


where it divides, some of it passing through the expansion device


32


and some of it passing through the expansion device


34


. From these expansion devices, the fluid continues to the two outside heat-exchange coils


16


and


28


where the fluid is warmed and evaporated by the outside air, this heat-exchange being assisted by the fans


38


and


42


respectively. This effectively cools the outside area. Heat-exchange fluid from the coils


16


and


28


in this condition of the equipment then passes respectively to the four-way valves


14


and


30


and thence to the input of the compressor


12


. Once again, in this condition of the equipment there is substantially no pressure differential across the apices


18


and


31


of the delta arrangement


20


, so that no fluid flows between these apices and it is as if they were disconnected.




Continued operation of the heat-exchange equipment in this second condition may ultimately result in the heat-exchange coils


16


and


28


becoming frosted up on their exteriors, resulting in reduced efficiency of the heat-exchange equipment. To remedy this, it is necessary for the coils to be warmed. Normally, this would prevent the heating effect of the heat pump equipment on the air of the enclosed region. However, with the delta arrangement described herein, it is possible to switch the valves


14


,


26


and


30


so that the output of the compressor


12


is connected to deliver hot gaseous heat-exchange fluid to one of the outside coils, say, coil


16


, as well as to the inside coil


24


. The fan


38


associated with that coil


16


would then be switched off. As a result, the heat-exchange fluid gives out heat from both of these coils


24


and


16


, although the fan


40


might be slowed in its rotational speed to take account of the fact that some of the heat from the fluid delivered by the compressor


12


is now passing out from the coil


16


. Fluid from both the coils


24


and


16


reach the delta arrangement


20


at apices


22


and


18


, respectively, and from thence pass through the expansion devices


34


and


36


, respectively, before merging at the apex


31


of the delta arrangement


20


. From here, the fluid flows through the coil


28


where it is heated and evaporated by the outside air. This heat-exchange is again assisted by the fan


42


. The heat-exchange fluid continues on its course through the valve


30


and thence back to the compressor


12


on the input side thereof.




In this third condition of the equipment, the pressure differential across the apices


18


and


22


is substantially zero so that substantially no fluid flows between those apices and it is as if they were disconnected and as if the expansion device


32


were absent.




In a fourth switching condition of the heat pump equipment, the valves


14


,


30


and


26


are arranged so that the compressor


12


feeds hot gaseous heat-exchange fluid from its output to the coils


24


and


28


via the valves


26


and


30


, respectively. The fan


42


associated with the coil


28


would then switched off. The fluid continues to the delta arrangement


20


reaching it at apices


22


and


31


from where it flows through the expansion devices


32


and


36


, respectively, and thence to merge at apex


18


, from which it flows to the coil


16


via the four-way valve


14


back to the input of the compressor


12


. In this condition of the heat pump equipment, the air of the enclosed region


44


is still heated, but the coil


28


is defrosted and the coil


16


is used to do all the heating of the heat-exchange fluid.




It will be appreciated that one of the ports of each four-way valve is blocked off.




In the event that the four-way valves are solenoid operated, the de-energised conditions are such that in the event that they are all de-energised, the compressor


12


is nonetheless connected to a viable circuit.




Numerous variations and modifications to the equipment illustrated in

FIG. 1

will occur to the reader without taking the resulting construction outside the scope of the first aspect of the present invention. For example, whilst the delta arrangement


20


is illustrated as a triangular form, the delta is not to be taken as requiring the appearance of a triangle. It could be circular, or indeed it could have any other form provided it is topographically equivalent. The refrigerant may be provided with a glide. The expansion devices may comprise orifice or capillary devices or any other form of expansion device and may or may not be connected in parallel with respective bi-directional or one-way valves as appropriate. The heat exchangers may be multiple path or single path heat exchangers.




In the event that the equipment illustrated in

FIG. 1

is for heating the air of the enclosed area only, for example, it is not necessary to provide the four-way valves.




Whilst the enclosed region has been described with reference to

FIG. 1

as being filled with air, in other applications it might be filled with a different fluid, for example water.




Heat pump equipment previously proposed has operated in a relatively inefficient way, for example, endeavouring to cool heat-exchange fluid by air that is already hot, or conversely in endeavouring to warm hot heat-exchange fluid with air that is already cool.




A second aspect of the present invention seeks to provide a remedy.




Accordingly, a second aspect of the present invention is directed to heat pump equipment comprising at least three heat exchangers connected in a heat-exchange fluid circuit, one of which heat exchangers is intended to be located in an enclosed region and another of which is intended to be located outside the enclosed region, and the third one of the heat exchangers is arranged so that air which flows through an aperture in a wall which forms a boundary of the enclosed region passes over the said third heat exchanger.




Preferably, the said third heat exchanger lies outside the enclosed region.




It is desirable to locate an expansion device between the said another heat exchanger and the said third heat exchanger. Desirably, there is a further expansion device connected between the said third heat exchanger and the said one heat exchanger. Preferably, each expansion device is connected in parallel with an associated one-way valve, each allowing flow in a direction towards the said third heat exchanger. It is desirable for a compressor to be connected between the said one heat exchanger and the said another heat exchanger, preferably via a reversing valve to provide greater flexibility for the equipment.




An air filter may be provided in the said aperture. The air filter may be kept dry by the said third heat exchanger.




The said second aspect of the present invention may be combined with the said first aspect of the present invention so that in addition to the heat exchangers referred to with reference to the first aspect of the present invention, a fourth heat exchanger is provided, being the said third heat exchanger with reference to the second aspect of the present invention.




Examples of the second aspect of the present invention are shown in

FIGS. 2 and 3

which show respective diagrammatic fluid circuits of two such examples.




The heat pump equipment


210


shown in

FIG. 2

comprises a compressor


212


, the output of which is connected to one end of a heat-exchange coil


214


via a reversing valve


213


. The other end of the coil


214


is connected to one end of a further heat-exchange coil


216


, the other end of which is connected to a further heat-exchange coil


218


via an expansion device


220


. The other end of the heat-exchange coil


218


returns back to the input side of the compressor


212


via the reversing valve


213


. Fans


222


,


224


and


226


are arranged to blow air over or draw air over the coils


214


,


216


and


218


, respectively.




The coil


214


is located within an enclosed region


228


. The coil


218


is outside this enclosed region, and a wall


230


forms a boundary for the enclosed region


228


. The fan


224


is positioned within an aperture


232


in the wall


230


, and the coil


216


is located adjacent to the aperture


232


on the outer side of the wall


230


so that the fan


224


draws air over the coil


216


.




With the heat pump equipment


210


so arranged, in a first condition of the equipment hot gaseous heat-exchange fluid is pumped from the compressor


212


to the coil


214


where it is cooled and condensed by the interior air with the assistance of the fan


222


, which air thereby becomes warmed. The heat-exchange fluid continues through the coil


216


to give up further heat to air which flows in through the aperture


232


in the wall


230


with the assistance of the fan


224


. This ensures that fresh air entering the building is already slightly warmed. The condensed heat-exchange fluid continues to the expansion device


220


and thence to the coil


218


where it draws in heat from the surrounding air with the assistance of a fan


226


. This causes the heat-exchange fluid to evaporate. From the coil


218


, it returns to the input suction end of the compressor


212


via the reversing valve


213


. In this condition, the heat pump equipment warms the air of the enclosed region and at the same time ensures in an efficient way that air from the outside entering the building via the aperture


232


is warmed a little.




By switching the reversing valve


213


, hot gaseous heat-exchange fluid from the compressor


212


can be passed to the coil


218


where it is condensed, heat passing to the outside air. From there the fluid is cooled at the expansion device


220


and passes to the coil


216


where the air drawn in to the aperture


232


by the fan


224


is slightly cooled before entering the enclosed region


228


. The heat-exchange fluid continues through the coil


214


where heat is drawn in from the air of the enclosed region


228


. The heat-exchange fluid then flows back to the input side of the compressor


212


via the reversing valve


213


.




In this condition of the heat-exchange equipment


210


, the air of the enclosed region


228


is cooled, and fresh air entering through the aperture


232


from the outside is cooled a little before it enters the enclosed region


228


.




The heat pump equipment


210


shown in

FIG. 2

can be modified to become the heat pump equipment


310


shown in FIG.


3


. This equipment has all the components of the equipment shown in

FIG. 2

, and like parts are labelled with the same reference numerals. In addition, the equipment


310


shown in

FIG. 3

has a one-way valve


312


connected in parallel with the expansion device


220


so that its allowed flow direction is from the coil


218


to the coil


216


. In addition, a further expansion device


314


is connected between the coil


214


and the coil


216


, and a one-way valve


316


is connected in parallel with the expansion device


314


so that its allowed direction of flow is from the coil


214


to the coil


216


.




During operation, the equipment


310


shown in

FIG. 3

operates in the same way as

FIG. 2

when the heat-exchange fluid flows in a clockwise direction, that is to say, from the compressor


212


to the coil


214


and then back via the coils


216


and


218


, to warm the air in the enclosed region


228


.




However, when the heat-exchange fluid flows in the other direction by reversal of the reversing valve


213


, the expansion device


220


is bypassed as the fluid flows preferentially through the one-valve


312


, and when it passes from the coil


216


to the coil


214


, because it would be flowing in the wrong direction for the one-way valve


316


, it flows preferentially through the expansion device


314


. When the equipment


310


is in this condition, the air inside the enclosed region


228


is cooled, whilst at the same time heat is given out from the coil


216


and may thereby be used to keep any filter


318


placed within the aperture


232


in a dry condition.




With the equipment thus arranged and in the second condition of operation, reversal of the direction of flow of the fan


224


will pass cool air from the interior of the enclosed region


228


over the coil


216


. This first cools the heat exchanger fluid in the coil


216


before it reaches the expansion device


314


, and improves the cooling capacity of the equipment.




Numerous variations and modifications to the equipment shown in

FIG. 2

or

FIG. 3

may occur to the reader without taking the resulting construction outside the scope of the second aspect of the present invention. For example, one or more of the heat exchangers may be multiple path heat exchangers.



Claims
  • 1. Heat pump equipment comprising at least three heat exchangers, one of which is intended to be located in an enclosed region and the other two of which are intended to be located outside the enclosed region, wherein the equipment further comprises a delta arrangement, and each heat exchanger has a delta connection end connected in heat-exchange fluid communication with the delta arrangement, such that the delta connection end of each heat exchanger is connected to both of the delta connection ends of the other two heat exchangers via the delta arrangement, in which arrangement there are three fluid-expansion devices, one between the two connections of each pair of adjacent connections of the heat exchangers to the delta arrangement.
  • 2. Equipment according to claim 1, wherein there is one compressor connected to receive heat-exchange fluid from and to feed heat-exchange fluid to the heat exchangers, and a valve arrangement connected between the compressor and the heat exchangers.
  • 3. Equipment according to claim 2, wherein the valve arrangement comprises a valve for each heat exchanger.
  • 4. Equipment according to claim 3, wherein each valve is a four-way valve.
  • 5. Heat pump equipment comprising at least three heat exchangers connected in a heat-exchange fluid circuit, a wall having an aperture therein and forming a boundary between an enclosed region and a region outside said enclosed region, one of said heat exchangers being located in said enclosed region, another of said heat exchangers being located in said region outside said enclosed region, and a third one of said heat exchangers being arranged so that air which flows through said aperture in said wall passes over said third one of said heat exchangers.
  • 6. Equipment according to claim 5, wherein said third one of said heat exchangers lies outside the enclosed region.
  • 7. Equipment according to claim 5, wherein an expansion device is provided between said another of said heat exchangers and said third one of said heat exchangers.
  • 8. Heat pump equipment comprising at least three heat exchangers connected in a heat-exchange fluid circuit, one of which heat exchangers is intended to be located in an enclosed region and another of which is intended to be located outside the enclosed region, wherein a third one of the heat exchangers is arranged so that air which flows through an aperture in a wall which forms a boundary of the enclosed region, passes over the said third heat exchanger, wherein an expansion device is provided between the said another heat exchanger and the said third heat exchanger, and wherein a further expansion device is provided connected between the said third heat exchanger and the said one heat exchanger.
  • 9. Equipment according to claim 8, further comprising air driving means to urge air to flow over the said third heat exchanger, the said driving means being reversible, so that air may be directed to flow from the interior of the enclosed region to the exterior of the enclosed region.
  • 10. Equipment according to claim 8, wherein each expansion device is connected in parallel with an associated one-way valve, each allowing flow in a direction towards the said third heat exchanger.
  • 11. Equipment according to claim 5, wherein a compressor is connected between said one of said heat exchangers and said another of said heat exchangers.
  • 12. Equipment according to claim 11, wherein a reversing valve is connected between said compressor and both said one of said heat exchangers and said another of said heat exchangers.
  • 13. Equipment according to claim 5, wherein an air filter is provided in said aperture.
Priority Claims (2)
Number Date Country Kind
0025122 Oct 2000 GB
0029307 Dec 2000 GB
US Referenced Citations (6)
Number Name Date Kind
4498295 Knoos Feb 1985 A
4646538 Blackshaw et al. Mar 1987 A
4949553 Suzuki Aug 1990 A
5243825 Lin Sep 1993 A
5711163 Uchikawa et al. Jan 1998 A
5771699 Ponder Jun 1998 A
Foreign Referenced Citations (2)
Number Date Country
6257902 Sep 1994 JP
406272996 Sep 1994 JP
Non-Patent Literature Citations (1)
Entry
Gieck K., Gieck R.; “Technische Formelsammlung”; 1989, Gieck, Germering, D, XP002208552; p. S10 (copy of ISR attached).