Operation of a cascade air conditioning system with two-phase loop

Patent metadata

Field	Value
Publication number	US-2016258657-A1
Application number	US-201415029824-A
Country	US
Kind code	A1
Filing date	Aug 14, 2014
Priority date	Oct 17, 2013
Publication date	Sep 8, 2016
Grant date	—

Abstract

A method of operating a heat transfer system includes starting operation of a first heat transfer fluid vapor/compression circulation loop including a fluid pumping mechanism, a heat exchanger for rejecting thermal energy from a first heat transfer fluid, and a heat absorption side of an internal heat exchanger. A first conduit in a closed fluid circulation loop circulates the first heat transfer fluid therethrough. Operation of a second two-phase heat transfer fluid circulation loop is started after starting operation of the first heat transfer fluid circulation loop. The second heat transfer fluid circulation loop transfers heat to the first heat transfer fluid circulation loop through the internal heat exchanger and includes a heat rejection side of the internal heat exchanger, a liquid pump, and a heat exchanger evaporator. A second conduit in a closed fluid circulation loop circulates a second heat transfer fluid therethrough.

First claim

1 . A method of operating a heat transfer system comprising:
starting operation of a first heat transfer fluid circulation loop including:
a fluid pumping mechanism;
a heat exchanger for rejecting thermal energy from a first heat transfer fluid; and
a heat exchanger for absorbing thermal energy into a first heat transfer fluid;
wherein a first conduit in a closed fluid circulation loop circulates the first heat transfer fluid therethrough; and
starting operation of a second two-phase heat transfer fluid circulation loop after starting operation of the first heat transfer fluid circulation loop, the second heat transfer fluid circulation loop exchanging heat with the first heat transfer fluid circulation loop through the internal heat exchanger and including:
a heat rejection side;
a liquid pump; and
a heat absorption side;
wherein a second conduit in a closed fluid circulation loop circulates a second heat transfer fluid therethrough.

2 . The method of claim 1 , wherein starting operation of the first heat transfer fluid circulation loop comprises:
opening a flow metering device; starting a heat exchanger fan; and starting the fluid pumping mechanism.

3 . The method of claim 2 , wherein the flow metering device is an expansion valve.

4 . The method of claim 1 , wherein the fluid pumping mechanism is a compressor.

5 . The method of claim 1 , further comprising flowing first heat transfer fluid through the internal heat exchanger prior to starting operation of the second two-phase heat transfer fluid circulation loop.

6 . The method of claim 5 , wherein flowing first heat transfer fluid through the internal heat exchanger via the first conduit is driven by startup of the fluid pumping mechanism.

7 . The method of claim 1 , wherein starting operation of the second heat transfer fluid circulation loop comprises starting the liquid pump.

8 . The method of claim 7 , further comprising starting a heat exchanger fan after starting the liquid pump.

9 . The method of claim 1 , wherein a time delay between starting operation of the first heat transfer fluid circulation loop and starting operation of the second heat transfer fluid circulation loop is between 0.1 second and 10 minutes.

10 . The method of claim 9 , wherein the time delay is between 0.1 second and 5 minutes.

11 . The method of claim 10 , wherein the time delay is between 0.1 second and 1 minute.

12 . The method of claim 1 , wherein the first fluid circulation loop is disposed at least partially outdoors.

13 . The method of claim 1 , wherein the second fluid circulation loop is disposed at least partially indoors.

14 . The method of claim 1 , wherein the second heat transfer fluid has an ASHRAE Class A toxicity rating and an ASHRAE Class 1 or 2L flammability rating.

15 . The method of claim 1 , wherein the first heat transfer fluid comprises propane, propene, isobutane, R32, R152a, ammonia, an R1234 isomer, or R410A, or a mixture of any of the above.

16 . The method of claim 1 , wherein the second heat transfer fluid comprises sub-critical fluid CO 2 .

17 . The heat transfer system of claim 1 , wherein the second heat transfer fluid comprises at least 50% liquid.

18 . A method of stopping operation of a heat transfer system comprising:
stopping operation of a first heat transfer fluid circulation loop including:
a fluid pumping mechanism;
a heat exchanger for rejecting thermal energy from a first heat transfer fluid; and
a heat exchanger for absorbing thermal energy into a first heat transfer fluid;
wherein a first conduit in a closed fluid circulation loop circulates the first heat transfer fluid therethrough; and
stopping operation of a second two-phase heat transfer fluid circulation loop after stopping operation of the first heat transfer fluid circulation loop, the second heat transfer fluid circulation loop exchanging heat with the first heat transfer fluid circulation loop through the internal heat exchanger and including:
a heat rejection side;
a liquid pump; and
a heat absorption side;
wherein a second conduit in a closed fluid circulation loop circulates a second heat transfer fluid therethrough.

19 . The method of claim 18 , wherein a time delay between stopping operation of the first heat transfer fluid circulation loop and stopping operation of the second heat transfer fluid circulation loop is between 0.01 second and 15 minutes.

20 . The method of claim 19 , wherein the time delay is between 0.1 second and 10 minutes.

21 . The method of claim 19 , wherein the time delay is between 0.1 second and 5 minute.

Assignees

• Carrier Corp

Inventors

• Feng Yinshan
• Wang Jinliang
• Zhao Futao
• Verma Parmesh
• Radcliff Thomas D

Classifications

• F25B7/00 Primary

  Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit (F25B9/00 takes precedence) · CPC title

• F25B9/008 Primary

  the refrigerant being carbon dioxide · CPC title

• F25B41/00

  Fluid-circulation arrangements · CPC title

• F25B23/006

  boiling cooling systems · CPC title

• F25B2500/26

  characterised by the startup of the refrigeration cycle · CPC title