Method for operating a refrigerant circuit as a heat pump and heat pump operable as a refrigerant circuit

Patent metadata

Field	Value
Publication number	US-9625188-B2
Application number	US-201514734535-A
Country	US
Kind code	B2
Filing date	Jun 9, 2015
Priority date	Dec 10, 2012
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A method of operating a refrigerant circuit as a heat pump is provided. By way of a compressor, refrigerant is compressed and is pumped through a refrigerant/heating heat exchanger. The refrigerant coming from the refrigerant/heating heat exchanger is expanded in at least a first expansion element. The refrigerant expanded by way of the first expansion element flows to a suction input of the compressor through at least one evaporator. At a branch-off point of the refrigerant/heating heat exchanger situated between a refrigerant input and a refrigerant output of the refrigerant/heating heat exchanger, refrigerant is branched off and is guided by way of a second expansion element in the direction of the suction input of the refrigerant compressor.

First claim

What is claimed is:

1. A method of operating a refrigerant circuit as a heat pump, the method comprising the acts of:
compressing a refrigerant, via a compressor, and pumping the compressed refrigerant through a refrigerant/heating heat exchanger;
expanding refrigerant coming from an output of the refrigerant/heating heat exchanger in at least a first expansion element;
flowing the expanded refrigerant from the first expansion element through at least one evaporator to an input of the compressor; and
branching-off the refrigerant at a branch-off point of the refrigerant/heating heat exchanger located between an input of the refrigerant/heating heat exchanger and the output; and
conducting the branched-off refrigerant, via a second expansion element, toward the suction input of the compressor.

2. The method according to claim 1 , further comprising the act of:
cooling the refrigerant between the refrigerant input and the branch-off point.

3. The method according to claim 2 , further comprising the act of:
cooling the refrigerant between the branch-off point and the refrigerant output in order to condense the refrigerant.

4. The method according to claim 3 , wherein the refrigerant is supercritically cooled between the branch-off point and the refrigerant output.

5. The method according to claim 1 , further comprising the acts of:
thermally coupling the refrigerant circuit via the refrigerant/heating heat exchanger with a heating circuit; and
flowing a fluid through the heating circuit, wherein the refrigerant/heating heat exchanger is a refrigerant/fluid heat exchanger.

6. The method according to claim 5 , wherein the heating circuit has a fluid pump with an adjustable flow rate.

7. The method according to claim 1 , wherein the refrigerant/heating heat exchanger is a refrigerant/air heat exchanger, the refrigerant/air heat exchanger emitting heat directly to an airflow to be heated.

8. The method according to claim 7 , wherein a first section of the refrigerant/air heat exchanger is between the refrigerant input and the branch-off point and a second section is between the branch-off point and the refrigerant output, and
wherein the first and second sections are connected in series on an airflow side such that the air flows through the first section after flowing through the second section.

9. The method according to claim 1 , further comprising the act of:
branching-off refrigerant coming from the refrigerant output of the refrigerant/heating heat exchanger and conducting the branched-off refrigerant, via a third expansion element, in a direction toward the suction input of the compressor.

10. The method according to claim 1 , further comprising the act of:
conducting the refrigerant from the at least one evaporator, by way of a accumulator, to the suction input of the compressor.

11. The method according to claim 10 , wherein the refrigerant conducted from the second expansion element flows to the suction input by way of the accumulator.

12. The method according to claim 11 , wherein the refrigerant conducted from the third expansion element flows to the suction input by way of the accumulator.

13. The method according to claim 1 , further comprising the act of:
automatically controlling a density of the refrigerant and/or a refrigerant mass flow at the suction input of the compressor by way of at least one of: the second expansion element, the third expansion element, or a rotational speed of the compressor.

14. The method according to claim 12 , further comprising the acts of:
at or upstream of a refrigerant input of the accumulator, measuring, via a pressure sensor, a pressure of the refrigerant and/or measuring, via a temperature sensor, a temperature of the refrigerant, and determining a density of the refrigerant therefrom.

15. The method according to claim 14 , the method further comprising the act of:
automatically controlling at least one of the second expansion element or the third expansion element as a function of at least one of the pressure or the temperature of the refrigerant.

16. The method according to claim 6 , further comprising the act of:
automatically controlling a density of the refrigerant at an input of the second expansion element via a rotational speed of the fluid pump.

17. A refrigerant circuit operable as a heat pump, comprising:
a compressor for compressing a refrigerant in the circuit;
a refrigerant/fluid heat exchanger arranged in a flow direction of the refrigerant downstream of the compressor, the refrigerant/fluid heat exchanger having a refrigerant input in fluid communication with a delivery side of the compressor and having a refrigerant output;
a first expansion element arranged downstream of the refrigerant output;
an evaporator arranged downstream of the first expansion element, the refrigerant from the evaporator flowing to a suction input of the compressor;
a refrigerant branch-off point located between the refrigerant input and the refrigerant output, by way of which refrigerant is conducted to the suction input of the compressor while bypassing the evaporator, the first expansion element, and a section of the refrigerant/fluid heat exchanger downstream of the branch-off point.

18. The refrigerant circuit according to claim 17 , further comprising:
a accumulator arranged between the evaporator and the suction input of the compressor or between the branch-off point and the suction input of the compressor.

19. The refrigerant circuit according to claim 18 , further comprising a second expansion element arranged between the branch-off point and the accumulator.

20. The refrigerant circuit according to claim 19 , further comprising a third expansion element arranged between the refrigerant output and the accumulator.

21. The refrigerant circuit according to claim 20 , wherein at least one of the second or third expansion element is an automatically controllable expansion element.

22. The refrigerant circuit according to claim 20 , wherein at least one of the second or the third expansion element is a throttle having a fixed cross-sectional flow.

23. The refrigerant circuit according to claim 17 , further comprising:
a heating circuit comprising an adjustable flow rate pump, a fluid being arranged to flow through the heating circuit, wherein
the refrigerant circuit is thermally coupled with the heating circuit by way of the refrigerant/fluid heat exchanger.

Assignees

• Bayerische Motoren Werke Ag

Inventors

• Satzger Peter
• Horn Oliver
• Herbolzheimer Robert
• Knott Martin
• Morgenstern Stefan
• Schedel Felix

Classifications

• B60H1/00914 Primary

  where the flow direction of the refrigerant does not change and there is a bypass of the condenser · CPC title

• F25B30/02 Primary

  of the compression type · CPC title

• B60H2001/00928

  comprising a secondary circuit · CPC title