Bi-directional cascade heat pump system

Patent metadata

Field	Value
Publication number	US-2016356531-A1
Application number	US-201615243039-A
Country	US
Kind code	A1
Filing date	Aug 22, 2016
Priority date	Dec 21, 2009
Publication date	Dec 8, 2016
Grant date	—

Abstract

A multi-mode, bi-directional cascade heat pump system, according to some examples, includes at least two chillers each being part of a unidirectional refrigerant circuit. The system includes heat exchangers each of which are dedicated to operate as just a condenser or as just an evaporator, regardless of the system's operating mode. In some modes, a secondary fluid transfers heat between the condenser of one chiller and the evaporator of another chiller before the fluid returns to a secondary fluid source such as, for example, a geothermal borefield or a conventional water source. In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield. The heat pump system includes means for minimizing flow through the borefield and for minimizing unnecessary mixing of relatively high and low temperature fluid.

First claim

1 - 16 . (canceled)

17 . A heat pump system operable with a refrigerant, a secondary fluid, a cooling load, and a heating load, the heat pump system comprising:
a chiller-A comprising a condenser-A and an evaporator-A; a chiller-B comprising a condenser-B and an evaporator-B; a secondary fluid source; a plurality of valves; and a fluid circulation loop conveying the secondary fluid and interconnecting the chiller-A, the chiller-B, the secondary fluid source, and the plurality of valves, the fluid circulation loop being connectable to the cooling load and the heating load, the plurality of valves being selectively configurable to place the heat pump system in the following modes:
an A/cooling mode to connect the evaporator-A in heat transfer relationship with the cooling load,
a B/cooling mode to connect the evaporator-B in heat transfer relationship with the cooling load,
an AB/cooling mode to connect the evaporator-A and evaporator-B in heat transfer relationship with the cooling load,
an A/heating mode to connect the condenser-A in heat transfer relationship with the heating load,
a B/heating mode to connect the condenser-B in heat transfer relationship with the heating load, and
an AB/heating mode to connect the condenser-A and the condenser-B in heat transfer relationship with the heating load.

18 . The heat pump system of claim 17 , wherein the chiller-A and the chiller-B are each part of a unidirectional refrigerant circuit.

19 . The heat pump system of claim 17 , wherein the chiller-A and the chiller-B each has a separate charge of refrigerant.

20 . The heat pump system of claim 17 , wherein the plurality of valves are further selectively configurable to place the heat pump system in an A/cooling-B/heating mode to connect the evaporator-A in heat transfer relationship with the cooling load and to connect the condenser-B in heat transfer relationship with the heating load.

21 . The heat pump system of claim 17 , wherein the plurality of valves are further selectively configurable to place the heat pump system in an A/heating-cooling mode to connect the condenser-A in heat transfer relationship with the heating load and to connect the evaporator-A in heat transfer relationship with the cooling load.

22 . The heat pump system of claim 21 , wherein the plurality of valves are further selectively configurable to place the heat pump system in a B/heating-cooling mode to connect the condenser-B in heat transfer relationship with the heating load and to connect the evaporator-B in heat transfer relationship with the cooling load.

23 . The heat pump system of claim 21 , wherein the plurality of valves are further selectively configurable to place the heat pump system in an AB/heating-cooling mode to connect the condenser-A in heat transfer relationship with the heating load, to connect the condenser-B in heat transfer relationship with the heating load, to connect the evaporator-A in heat transfer relationship with the cooling load, and to connect the evaporator-B in heat transfer relationship with the cooling load.

24 . The heat pump system of claim 17 , wherein the secondary fluid source is a geothermal fluid source.

25 - 28 . (canceled)

29 . The heat pump system of claim 24 , wherein the geothermal fluid source includes a substantially closed loop system, wherein the secondary fluid circulates between the geothermal fluid source and the fluid circulation loop.

30 . The heat pump system of claim 24 , wherein the geothermal fluid source includes an open system, wherein at least some of the secondary fluid circulating between the geothermal fluid source and the fluid circulation loop fails to return to the geothermal fluid source.

Assignees

• Trane Int Inc

Inventors

• Cline Lee R
• Schwedler Michael C A
• Hanson Susanna S
• Fiegen Brian J

Classifications

• F25B49/02

  for compression type machines, plants or systems · CPC title

• F25B2400/06

  Several compression cycles arranged in parallel · CPC title

• F25B7/00

  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

• F25B2700/21

  Temperatures · CPC title

• F25B30/06 Primary

  characterised by the source of low potential heat · CPC title