CROSS-REFERENCE TO RELATED APPLICATIONS

This patent appl ication claims priority from Italian patent application no . 102020000021097 filed on 07 / 09/2020 , the entire disclosure of which is incorporated herein by reference .

TECHNICAL FIELD

This invention relates to a reversible heat pump .

BACKGROUND ART

In particular, this invention relates to a heat pump of the type comprising a first refrigeration circuit traversed by carbon dioxide and comprising, in turn, a first expansion device for reducing the pressure and temperature of the carbon dioxide , a first evaporator device designed to receive the incoming carbon dioxide from the first expansion device , a first compressor device designed to receive the incoming carbon dioxide from the first evaporator device , a first cooling device to cool the carbon dioxide coming from the first compressor device , and a second cooling device to cool the carbon dioxide coming from the first cooling device and to feed the outgoing carbon dioxide to the first expansion device .

The heat pump further comprises a first hydraulic circuit to feed a source liquid, in this case water or a mix of water and anti freeze , through the first evaporator device and to cause the evaporation of the carbon dioxide .

The heat pump has , in addition, a second refrigeration circuit traversed by a refrigerating fluid other than carbon dioxide and comprising, in turn, a second expansion device to reduce the pressure and temperature of the refrigerating fluid and to feed the outgoing refrigerating fluid to the second cooling device , a second compressor device designed to receive the incoming refrigerating fluid from the second cooling device , and a condenser device designed to receive the incoming refrigerating fluid from the second compressor device and to feed the outgoing refrigerating fluid to the second expansion device .

The heat pump is also provided with a second hydraulic circuit to heat a utility liquid, in this case water from a heating system, through the first cooling device of the first refrigeration circuit and through the condenser device of the second refrigeration circuit .

Since the second hydraulic circuit is configured to feed and, therefore , heat , in succession, the utility liquid first through the condenser device of the second refrigeration circuit and, then, through the first cooling device of the first refrigeration circuit , the known heat pumps of the type described above have some drawbacks mainly deriving from the fact that , when the di f ference in temperature between the utility liquid coming in and going out of the utility is relatively small , the utility liquid traverses the first cooling device of the first refrigeration circuit at a temperature already close to the inlet temperature in the utility .

As a result , the cooling of the carbon dioxide in the first cooling device of the first refrigeration circuit is relatively reduced and, thus , the ef ficiency of the heat pump is relatively reduced .

DISCLOSURE OF INVENTION

The obj ect of this invention is to provide a reversible heat pump that resolves the drawbacks described above and that is simple and economical to implement .

According to this invention, a reversible heat pump is provided, as claimed in the attached claims .

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will now be described with reference to the attached drawings that schematically illustrate a nonlimiting embodiment thereof .

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the attached f igure , the reference number 1 denotes , as a whole , a reversible heat pump that has a first refrigeration circuit 2 traversed by carbon dioxide as a refrigerating fluid .

The circuit 2 comprises an expansion device 3 for reducing the pressure and temperature of the carbon dioxide ; an evaporator device 4 designed to receive incoming carbon dioxide in the two-phase liquid- vapour mixture state coming from the expansion device 3 and to release outgoing carbon dioxide in the vapour or two-phase liquid- vapour mixture state close to the saturation curve ; a compressor device 5 designed to receive the incoming carbon dioxide in the vapour state or from the evaporator device 4 and to increase the pressure and temperature of the carbon dioxide itsel f ; a first cooling device 6 designed to receive the incoming carbon dioxide from the compressor device 5, and a second cooling device 7 designed to receive the incoming carbon dioxide from the cooling device 6 and to feed the outgoing carbon dioxide to the expansion device 3 .

The circuit 2 comprises , in addition, an ej ector device 8 that has a first inlet 9 connected to the cooling device 7 and a second inlet 10 connected to the evaporator device 4 , and a f irst separator device 11 that has an inlet 12 connected to the ej ector device 8 , a first outlet 13 to feed carbon dioxide in the liquid state to the expansion device 3 and a second outlet 14 to feed carbon dioxide in the vapour state to the compressor device 5 .

With reference to what is described above , it is useful to speci fy that the pressure of the carbon dioxide fed by the ej ector device 8 to the separator device 11 and, thus , to the intake of the compressor device 5 ranges between the pressure of the carbon dioxide fed to the ej ector device 8 through the inlet 9 and the pressure of the carbon dioxide fed to the ej ector device 8 through the inlet 10 . As a result , since the pressure of the carbon dioxide fed by the ej ector device 8 to the compressor device 5 is greater than the pressure of the carbon dioxide fed by the evaporator device 4 to the ej ector device 8 , the work of the compressor device 5 is relatively reduced .

The circuit 2 comprises , in addition, a second separator device S mounted between the compressor device 5 and the cooling device 6 so as to separate the carbon dioxide from the lubrication oil of the compressor device 5 .

The heat pump 1 has , in addition, a second refrigeration circuit 15 traversed by a refrigerating fluid other than carbon dioxide and comprising an expansion device 16 to reduce the pressure and temperature of the refrigerating fluid and to feed the outgoing refrigerating fluid through the cooling device 7 so as to cause the refrigerating fluid to evaporate , a compressor device 17 designed to receive the incoming refrigerating fluid coming from the cooling device 7 , and a condenser device 18 designed to receive the incoming refrigerating fluid from the compressor device 17 and to feed the outgoing refrigerating fluid to the expansion device 16 .

The heat pump 1 comprises , in addition, a utility 19 traversed by a utility liquid, in this case water from a heating/air conditioning system, and a source 20 traversed by a source liquid, in this case water or a mixture of water and anti freeze .

The heat pump 1 is , in addition, configured to operate both according to a winter operating mode , wherein the utility liquid is heated, and according to a summer operating mode , wherein the utility liquid is cooled .

In the winter operating mode , the heat pump 1 comprises a first hydraulic circuit 21 for feeding the source liquid along a closed ring path extending through the source 20 and though the evaporator device 4 and making the carbon dioxide of the circuit 2 evaporate .

The circuit 21 comprises a first segment 22 extending through the source 20 , and a second segment 23 , which extends through the evaporator device 4 , is connected to the segment 22 at two valve devices 24 , 25, and is equipped with a feeding pump 26 designed to ensure the circulation of the source liquid along the circuit 21 itself .

In the winter operating mode , the heat pump 1 comprises , in addition, a second hydraulic circuit 27 for feeding the utility liquid through the utility 19 and through the cooling device 6 of the circuit 2 and the condenser device 18 of the circuit 15 and for heating the utility liquid itsel f .

The circuit 27 is configured to feed the utility liquid, in succession and in order, first through the cooling device 6 and, then, through the condenser device 18 .

The circuit 27 comprises two portions 28 , 29 closed in a ring, and wherein : the portion 28 extends through the utility 19 and through a heat exchanger 30 , and i s provided with a feeding pump 31 designed to ensure the circulation of the utility liquid along the portion 28 itsel f ; and the portion 29 extends through the cooling device 6 , the condenser device 18 , and the heat exchanger 30 , and is provided with a feeding pump 32 designed to ensure the circulation of the utility liquid along the portion 29 itsel f .

The portion 29 comprises a first segment 33 extending between the two valve devices 24 and 25 and through the exchanger 30 , and a second segment 34 extending between the two valve devices 24 and 25 and through the cool ing device 6 and the condenser device 18 .

In the summer operating mode : the segment 33 is connected to the segment 23 to define , together with the portion 28 , a hydraulic circuit designed to feed the utility liquid through the evaporator device 4 ; the segment 34 is connected to the segment 22 in order to define a hydraulic circuit designed to feed the source liquid through the cooling device 6 and the condenser device 18 ; the utility liquid is cooled in the evaporator device 4 ; the source liquid is heated in the cooling device 6 and in the condenser device 18 .

Naturally, the valve devices 24 , 25 can be moved between respective first operating positions , in which the heat pump 1 operates according to the winter operating mode , and respective second operating positions , in which the heat pump 1 operates according to the summer operating mode .

According to a variant not illustrated, the heat exchanger 30 is eliminated and the portion 28 and the segment 33 are eliminated and replaced with a segment of the circuit 27 extending through the utility 19 and connected to the segment 34 at the valve devices 24 and 25 .

The heat pump 1 has some advantages mainly deriving from the fact that the utility liquid is fed in succession first through the cooling device 6 and, then, through the condenser device 18 .

Since , thus , the utility liquid temperature in the cooling device 6 is lower than the temperature of the utility liquid in the condenser device 18 , the carbon dioxide in the circuit 2 is additionally cooled by the utility liquid that is at a lower temperature .

As a result, the cooling of the carbon dioxide in the cooling device 6 is relatively high and, thus , the ef ficiency of the heat pump 1 is relatively high, including when the di f ference in temperature of the utility liquid between the inlet and outlet of the utility 19 is relatively reduced, thanks to the cooling device 7 connected to the circuit 15 that ensures elevated ef ficiency of the carbon dioxide cycle .