BI-DIRECTIONAL CASCADE HEAT PUMP SYSTEM

摘要

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 In some embodiments, fluid is withdrawn from a borefield by way of a pump having a speed that varies to maintain a desired fluid temperature and/or a desired heat transfer rate at the borefield.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.

主权项

1. A heat pump system operable with a refrigerant and a secondary fluid, the heat pump system comprising:
a geothermal fluid source; a first chiller having a first heat exchanger; a second chiller having a second heat exchanger; and a fluid circulation loop coupling the geothermal fluid source in heat transfer relationship with the first chiller and the second chiller such that the secondary fluid flows from the geothermal fluid source, then flows sequentially through the first heat exchanger and the second heat exchanger, but not necessarily in that order, and then flows back to the geothermal fluid source.