Refrigeration System

• US 20080060365A1
• Filed: 08/31/2005
• Published: 03/13/2008
• Est. Priority Date: 09/01/2004
• Status: Abandoned Application

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: Sakitani, Katsumi, Sasaki, Yoshinari, Moriwaki, Michio, Inokuchi, Yume
• Application Number:
  US11/661,383
• Publication Number:
  US 20080060365A1
• Time in Patent Office: Days
• US Class Current: 62/114
• CPC Class Codes: F25B 1/04 with compressor of rotary type F25B1/005, F25B1/10 take precedence
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2309/061 with cycle highest pressure above the supercritical pressure
• CPC Class Codes: F25B 2313/006 two pipes connecting the outdoor side to the indoor side with multiple indoor units
• CPC Class Codes: F25B 2313/0272 using bridge circuits of one-way valves
• CPC Class Codes: F25B 2313/02741 using one four-way valve
• CPC Class Codes: F25B 2313/02742 using two four-way valves
• CPC Class Codes: F25B 2400/14 Power generation using energy from the expansion of the refrigerant
• CPC Class Codes: F25B 2400/23 Separators
• CPC Class Codes: F25B 2500/02 Increasing the heating capacity of a reversible cycle during cold outdoor conditions
• CPC Class Codes: F25B 40/00 Subcoolers, desuperheaters or superheaters
• CPC Class Codes: F25B 9/008 the refrigerant being carbon dioxide
• CPC Class Codes: F25B 9/06 using expanders F25B9/10 takes precedence
• CPC Class Codes: F28D 7/106 consisting of two coaxial conduits or modules of two coaxial conduits

Abstract

A refrigeration system includes an internal heat exchanger (23) capable of controlling the temperature of refrigerant flowing towards an expander (12). Upon change of the operating conditions, the internal heat exchanger (23) controls the temperature of the refrigerant to control the specific volume or the flow rate of the refrigerant, thereby eliminating imbalance between the flow rate through a compressor (11) and the flow rate through the expander (12). In a cooling operation in which the refrigerant circulation amount is larger than in a heating operation, the cooling capacity of the internal heat exchanger (23) is enhanced as compared to that in the heating operation, thereby increasing the flow rate of refrigerant into the expander (12) without part of the refrigerant bypassing the expander (12). This prevents the COP of the refrigeration system from being deteriorated.

Claims

1. A refrigeration system including a refrigerant circuit (10) in which a compressor (11), a heat-source side heat exchanger (21), an expansion mechanism (12) and a utilization side heat exchanger (22) are connected to provide a vapor compression refrigeration cycle, the expansion mechanism (12) being constituted by an expander (12) for generating power by the expansion of refrigerant, the expander (12) being mechanically connected to the compressor (11), the refrigeration system further comprising

a temperature controller (23) capable of controlling the temperature of refrigerant flowing towards the expander (12).

2. The refrigeration system of claim 1, wherein

the refrigerant circuit (10) is configured to be capable of a heating operation in which refrigerant flowing through the utilization side heat exchanger (22) releases heat and a cooling operation in which refrigerant flowing through the utilization side heat exchanger (22) takes heat, and

the temperature controller (23) is configured to have a higher capacity to cool refrigerant flowing towards the expander (12) during the cooling operation than during the heating operation.

3. The refrigeration system of claim 2, wherein the temperature controller (23) is constituted by an internal heat exchanger (23) in which, during the cooling operation, refrigerant after passing through the heat-source side heat exchanger (21) serving as a gas cooler is cooled by heat exchange with refrigerant before or after passing through the utilization side heat exchanger (22) serving as an evaporator.

4. The refrigeration system of claim 3, wherein the internal heat exchanger (23) is configured so that, during the cooling operation, a refrigerant channel (25) thereof through which refrigerant before or after passing through the utilization side heat exchanger (22) serving as an evaporator flows has a higher heat transfer capacity than a refrigerant channel (24) thereof through which refrigerant after passing through the heat-source side heat exchanger (21) serving as a gas cooler flows and that, during the heating operation, the refrigerant channel (24) through which refrigerant before or after passing through the heat-source side heat exchanger (21) serving as an evaporator flows has a lower heat transfer capacity than the refrigerant channel (25) through which refrigerant after passing through the utilization side heat exchanger (22) serving as a gas cooler flows.

5. The refrigeration system of claim 4, wherein the internal heat exchanger (23) includes a heat transfer fin (26) provided on the refrigerant channel (25) through which, during the cooling operation, refrigerant before or after passing through the utilization side heat exchanger (22) serving as an evaporator flows and, during the heating operation, refrigerant after passing through the utilization side heat exchanger (22) serving as a gas cooler flows.

6. The refrigeration system of claim 3, wherein the internal heat exchanger (23) is configured so that, during the cooling operation, refrigerant before or after passing through the utilization side heat exchanger (22) serving as an evaporator and refrigerant after passing through the heat-source side heat exchanger (21) serving as a gas cooler flow therethrough in opposite directions to each other and that, during the heating operation, refrigerant before or after passing through the heat-source side heat exchanger (21) serving as an evaporator and refrigerant after passing through the utilization side heat exchanger (22) serving as a gas cooler flow therethrough in the same direction.

7. The refrigeration system of claim 3, wherein the internal heat exchanger (23) is constituted by a double-pipe heat exchanger including an inner channel (24) and an outer channel (25) disposed adjacent each other.

8. The refrigeration system of claim 3, wherein the internal heat exchanger (23) is constituted by a three-layered plate heat exchanger including an inner channel (24), a first outer channel (25A) disposed adjacent an outside of the inner channel (24) and a second outer channel (25B) disposed adjacent another outside of the inner channel (24).

9. A refrigeration system including a refrigerant circuit (10) in which a compressor (11), a heat-source side heat exchanger (21), an expansion mechanism (12) and a utilization side heat exchanger (22) are connected to provide a vapor compression refrigeration cycle, the refrigerant circuit (10) being configured to be capable of a heating operation in which refrigerant flowing through the utilization side heat exchanger (22) releases heat and a cooling operation in which refrigerant flowing through the utilization side heat exchanger (22) takes heat, the expansion mechanism (12) being constituted by an expander (12) for generating power by the expansion of refrigerant, the expander (12) being mechanically connected to the compressor (11), the refrigeration system further comprising

a temperature controller (23) capable of controlling the temperature of high-pressure refrigerant flowing towards the expander (12),

the temperature controller (23) being configured to cool the high-pressure refrigerant only during the cooling operation but stop the cooling of the high-pressure refrigerant during the heating operation.

10. The refrigeration system of claim 9, wherein the temperature controller (23) is constituted by an internal heat exchanger (23) in which during the cooling operation the high-pressure refrigerant is cooled by heat exchange with low-pressure refrigerant.

11. The refrigeration system of claim 10, wherein

the internal heat exchanger (23) includes a first channel (27) and a second channel (28) and is configured to be capable of heat exchange between refrigerant flowing through the first channel (27) and refrigerant flowing through the second channel (28), and

the internal heat exchanger (23) is configured so that, during the cooling operation, high-pressure refrigerant flows through the first channel (27) and low-pressure refrigerant flows through the second channel (28) and that, during the heating operation, high-pressure refrigerant flows through both the channels (27, 28).

12. The refrigeration system of claim 10, wherein

the internal heat exchanger (23) includes a first channel (27) and a second channel (28) and is configured to be capable of heat exchange between refrigerant flowing through the first channel (27) and refrigerant flowing through the second channel (28),

the internal heat exchanger (23) is configured so that, during the cooling operation, high-pressure refrigerant flows through the first channel (27) and low-pressure refrigerant flows through the second channel (28), and

the refrigeration system further comprises a bypass passage (45) that, during the heating operation, allows high-pressure refrigerant to bypass the internal heat exchanger (23).

13. The refrigeration system of claim 10, wherein

the internal heat exchanger (23) includes a first channel (27) and a second channel (28) and is configured to be capable of heat exchange between refrigerant flowing through the first channel (27) and refrigerant flowing through the second channel (28),

the internal heat exchanger (23) is configured so that, during the cooling operation, high-pressure refrigerant flows through the first channel (27) and low-pressure refrigerant flows through the second channel (28), and

the refrigeration system further comprises a bypass passage (46) that, during the heating operation, allows low-pressure refrigerant to bypass the internal heat exchanger (23).

14. The refrigeration system of claim 10, wherein the internal heat exchanger (23) is configured so that, during the cooling operation, high-pressure refrigerant after passing through the heat-source side heat exchanger (21) is cooled therein by heat exchange with low-pressure refrigerant before passing through the utilization side heat exchanger (22).

15. The refrigeration system of claim 10, wherein the internal heat exchanger (23) is configured so that, during the cooling operation, high-pressure refrigerant after passing through the heat-source side heat exchanger (21) is cooled therein by heat exchange with low-pressure refrigerant after passing through the utilization side heat exchanger (22).

16. The refrigeration system of claim 10, wherein the internal heat exchanger (23) is configured so that, during the cooling operation, high-pressure refrigerant and low-pressure refrigerant flow therethrough in opposite directions to each other.

17. The refrigeration system of claim 9, wherein refrigerant in the refrigerant circuit (10) is carbon dioxide.

18. A refrigeration system including a refrigerant circuit (10) in which a compressor (11), a heat-source side heat exchanger (21), an expander (12) and a utilization side heat exchanger (22) are connected to provide a refrigeration cycle, the compressor (11) being mechanically connected to the expander (12) to recover expansion power from the expander (12), the refrigeration system further comprising

a gas-liquid separator (51) for separating refrigerant expanded by the expander (12) into a liquid refrigerant and a gas refrigerant and temporarily storing the liquid and gas refrigerants,

the gas-liquid separator (51) comprising an internal heat exchange part (50) for exchanging heat between the liquid refrigerant separated in the gas-liquid separator (51) and refrigerant to be introduced into the expander (12).

19. The refrigeration system of claim 18, further comprising a heat exchange control mechanism (60) for changing the amount of heat exchange of refrigerant in the internal heat exchange part (50) according to the operating conditions.

20. The refrigeration system of claim 19, wherein

the gas-liquid separator (51) further comprises a liquid storage section (52) for storing the separated liquid refrigerant and a heat transfer tube (50) which is disposed adjacent the liquid storage section (52) and through which the refrigerant to be introduced into the expander (12) flows, and

the heat transfer tube (50) constitutes an internal heat exchange part for exchanging heat between the liquid refrigerant in the liquid storage section (52) and the refrigerant in the heat transfer tube (50).

21. The refrigeration system of claim 20, further comprising

a refrigerant switching mechanism (31, 33) for switching the circulation direction of refrigerant in the refrigerant circuit (10) to selectively provide either the cooling operation or the heating operation,

wherein the heat exchange control mechanism (60) allows heat exchange of refrigerant in the internal heat exchange part (50) only during the cooling operation.

22. The refrigeration system of claim 21, wherein the heat exchange control mechanism (60) is constituted by a bypass pipe (57) allowing refrigerant to bypass the heat transfer tube (50) and then flow into the expander (12), a first motor-operated valve (36) for controlling the flow rate of refrigerant flowing through the heat transfer tube (50), and a second motor-operated valve (37) for controlling the flow rate of refrigerant through the bypass pipe (57).

23. The refrigeration system of claim 21, wherein the heat exchange control mechanism (60) is constituted by a four-way selector valve (32).

24. The refrigeration system of claim 21, wherein the heat exchange control mechanism (60) is constituted by a bypass pipe (57) allowing refrigerant to bypass the heat transfer tube (50) and then flow into the expander (12), a first solenoid shut-off valve (34) selectively allowing or inhibiting the flow of refrigerant through the heat transfer tube (50), and a second solenoid shut-off valve (35) selectively allowing or inhibiting the flow of refrigerant through the bypass pipe (57).

25. The refrigeration system of claim 21, wherein the heat exchange control mechanism (60) is constituted by a combination of pipes and check valves (81, 82, 83, 84).

26. The refrigeration system of claim 18, wherein the refrigerant circuit (10) further includes a first injection pipe (55) for sending the gas refrigerant in the gas-liquid separator (51) to the suction side of the compressor (11) and a gas control valve (38) for controlling the flow rate of refrigerant through the first injection pipe (55).

27. The refrigeration system of claim 18, wherein the refrigerant circuit (10) further includes a second injection pipe (59) for sending the liquid refrigerant in the gas-liquid separator (51) to the suction side of the compressor (11) and a liquid control valve (39) for controlling the flow rate of refrigerant through the second injection pipe (59).

28. The refrigeration system of claim 18, wherein

a plurality of said utilization side heat exchangers (22a, 22b, 22c) are connected in parallel with each other in the refrigerant circuit (10), and

the refrigeration system further comprises a plurality of flow control valves (61a, 61b, 61c) each for controlling the flow rate of refrigerant flowing into an associated one of the plurality of utilization side heat exchangers (22a, 22b, 22c).

29. The refrigeration system of claim 18, wherein carbon dioxide is used as the refrigerant in the refrigerant circuit (10).