Systems and methods for control of superheat from a subcooler

Abstract

Systems and methods for controlled subcooling of working fluid in a heating, ventilation, air conditioning and refrigeration (HVACR) system through a suction line heat exchanger are disclosed. The suction line heat exchanger may receive a first fluid flow travelling to a suction of the compressor in the HVACR system and second flow of working fluid that is travelling from a heat exchanger receiving the discharge of the compressor to an expansion device. Superheating of the first working fluid may be determined based on temperature measurements prior to and following the suction line heat exchanger. The superheating may be used to control the quantity of the second flow of working fluid introduced into the suction line heat exchanger, for example to maintain superheat that is below a threshold value. These systems may include chillers and heat pump systems, and methods may be applied to chillers or heat pump systems.

1 - 22 . (canceled) 
     
     
         23 . A heating, ventilation, air conditioning, and refrigeration (HVACR) circuit, comprising:
 a compressor having a suction and a discharge;   a first heat exchanger;   an expander;   a second heat exchanger;   a suction line heat exchanger, configured to exchange heat between a first working fluid flow, wherein the first working fluid flow is a flow of working fluid from one of the first heat exchanger and the second heat exchanger to the suction of the compressor, and a second working fluid flow, wherein the second working fluid flow is a flow of working fluid from the other of the first heat exchanger and the second heat exchanger towards the expander;   a flow director located upstream of the suction line heat exchanger with respect to the second working fluid flow, the flow director configured to provide a variable quantity of the second working fluid flow to the suction line heat exchanger.   
     
     
         24 . The HVACR circuit of  claim 23 , wherein the first heat exchanger is an outdoor heat exchanger receiving working fluid from the discharge of the compressor, the second heat exchanger is an evaporator, the first working fluid flow is from the second heat exchanger to the suction of the compressor, and the second working fluid flow is from the first heat exchanger to the expander. 
     
     
         25 . The HVACR circuit of  claim 23 , further comprising a flow reverser configured to direct the working fluid from a discharge of the compressor to one of the first heat exchanger and the second heat exchanger. 
     
     
         26 . The HVACR circuit of  claim 25 , wherein the HVACR circuit is in a cooling mode when the flow reverser directs the working fluid from a discharge of the compressor to the first heat exchanger, and a heating mode when the flow reverser directs the working fluid from the discharge of the compressor to the second heat exchanger. 
     
     
         27 . The HVACR circuit of  claim 26 , wherein when in the cooling mode, the first working fluid flow is from the second heat exchanger to the suction of the compressor, and the second working fluid flow is from the first heat exchanger to the expander. 
     
     
         28 . The HVACR circuit of  claim 27 , wherein when in the heating mode, the first working fluid flow is from the first heat exchanger to the suction of the compressor, and the second working fluid flow is from the second heat exchanger to the expander. 
     
     
         29 . The HVACR circuit of  claim 23 , wherein the suction line heat exchanger is a counter-flow heat exchanger. 
     
     
         30 . The HVACR circuit of  claim 23 , wherein the flow director comprises a stepped three-way valve and a bypass line. 
     
     
         31 . The HVACR circuit of  claim 23 , wherein the flow director comprises a plurality of controllable valves.