Patent ID: 11953240
Assignee: TRANE INTERNATIONAL INC.
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F | IPC F

Claim 5:
6. A method of operating a reversible heat pump system to control the temperature of a process fluid of a chiller system, the reversible heat pump system comprising:
a compressor, a first heat exchanger, an expansion device, a second heat exchanger for heat exchange with the process fluid of the chiller system, and a suction line economiser heat exchanger;
the method comprising:
a controller determining whether to operate the reversible heat pump system in a cooling mode to cool the process fluid, or in a heating mode to heat the process fluid;
when in the cooling mode, circulating a working fluid through the reversible heat pump system so that compressed working fluid from the compressor rejects heat at the first heat exchanger to provide condensed working fluid to a liquid line, and so that expanded working fluid from the expansion device receives heat from the process fluid at the second heat exchanger to provide superheated working fluid along a suction line to the compressor;
when in the heating mode, circulating the working fluid through the reversible heat pump system so that compressed working fluid from the compressor rejects heat to the process fluid at the second heat exchanger to provide condensed working fluid to the liquid line, and so that the expanded working fluid from the expansion device receives heat at the first heat exchanger to provide downstream superheated working fluid along the suction line to the compressor;
wherein the process fluid is provided to the second heat exchanger along a process fluid pathway from a process fluid inlet to a process fluid outlet, for heat exchange between the process fluid and the working fluid;

wherein a direction of working fluid flow through the second heat exchanger opposes the flow of process fluid along the process fluid pathway in the heating mode to provide a counterflow arrangement, such that in the heating mode an inlet for providing working fluid to the second heat exchanger is proximal to the process fluid outlet;
wherein a direction of working fluid flow through the second heat exchanger corresponds to the flow of process fluid along the process fluid pathway in the cooling mode to provide a co-current flow arrangement, such that in the cooling mode the inlet for providing working fluid to the second heat exchanger is proximal to the process fluid inlet;
wherein in each of the cooling mode and the heating mode, condensed working fluid upstream of the expansion device transfers heat to superheated working fluid upstream of the compressor, at the suction line economiser heat exchanger,, further comprising monitoring one or more parameters relating to (i) a temperature of the working fluid at a location along the suction line and/or (ii) a pressure of the working fluid at a location along the suction line;
wherein the expansion device is controlled to maintain a target superheat of the working fluid at a target location along the suction line;
wherein the method further comprises:
determining a saturation temperature parameter corresponding to a saturation temperature of the working fluid in the suction line;
wherein the control to maintain the target superheat is at least partly based on the saturation temperature parameter.