Reversible heat pump

Patent metadata

Field	Value
Publication number	US-11953240-B2
Application number	US-202217668109-A
Country	US
Kind code	B2
Filing date	Feb 9, 2022
Priority date	Feb 9, 2021
Publication date	Apr 9, 2024
Grant date	Apr 9, 2024

Abstract

There is disclosed a reversible heat pump system 100 and a method of operating a reversible heat pump system to control the temperature of a process fluid of a chiller system 500. In a cooling mode, a working fluid is circulated for co-current flow with a process fluid at a heat exchanger 104 functioning as an evaporator heat exchanger, whereas in a heating mode, the working fluid is circulated for counter-current flow with the process fluid at the same heat exchanger 104 functioning as a condenser heat exchanger.

First claim

The invention claimed is:

1. 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 controlling the expansion device to maintain a thermodynamic condition of the working fluid at a target location along the suction line;
and wherein:
the expansion device and a modulation device are controlled so that the working fluid is maintained at superheated conditions in the suction line, with a target superheat of at least a first superheat upstream of the suction line economiser heat exchanger, and with a target superheat of at least a second greater superheat downstream of the suction line economiser heat exchanger.

2. The method according to claim 1 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; and
wherein the expansion device is controlled to maintain a target superheat of the working fluid at a target location along the suction line.

3. The method according to claim 1 , further comprising controlling a modulation device disposed along the liquid line upstream of the expansion device, to maintain a target change of temperature of the expanded working fluid through the suction line economiser heat exchanger; and/or to maintain a target superheat of the working fluid at a target location along the suction line.

4. The method according to claim 3 , further comprising monitoring temperature parameters relating to (i) a temperature of the working fluid in the suction line upstream of the suction line economiser heat exchanger and (ii) a temperature of the working fluid in the suction line downstream of the suction line economiser heat exchanger; and
controlling the modulation device to maintain the target change of temperature based on the monitored temperature parameters.

5. The method according to claim 3 , wherein the modulation device comprises a three-way valve in the liquid line for variably distributing a flow of condensed working fluid between a first liquid line branch to the suction line economiser heat exchanger and a second liquid line branch that bypasses the suction line economiser heat exchanger;
wherein controlling the modulation device comprises varying a distribution of the flow between the first and second liquid line branches.

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 worki

Assignees

• Trane Int Inc

Inventors

• Raimbault Yves Jacques
• Huang Qingnan

Classifications

• F25B30/02 Primary

  of the compression type · CPC title

• F25B13/00 Primary

  Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02) · CPC title

• F25B29/003

  of the compression type system · CPC title

• F25B40/06

  Superheaters · CPC title

• F25B2313/02731

  using one three-way valve · CPC title