Heat transfer circuit with flow dependent heat exchanger

Abstract

A heat transfer circuit includes a compressor, a heat exchanger, an expander, a plurality of valves, and a working fluid. The heat exchanger including a plurality of coils and is configured to exchange heat between the working fluid and a process fluid. The working fluid flows through the first heat exchanger in a first direction by flowing through the plurality of coils in series and in a second direction by flowing through the plurality of coils in parallel. A method of operating a heat transfer circuit includes operating in a first mode and operating in a second mode. In the first mode, working fluid flows though coils of a heat exchanger in series. In a second mode, the working fluid flows through the coils of the heat exchanger in parallel.

What is claimed is: 
     
         1 . A heat transfer circuit operable in at least a first mode and a second mode, the heat transfer circuit comprising:
 a compressor to compress a working fluid;   an expander to expand the working fluid;   a first heat exchanger to exchange heat between the working fluid and a first process fluid, the first heat exchanger including a plurality of heat exchange coils, the working fluid flowing through the plurality of heat exchange coils, the first process fluid flowing through the plurality of heat exchange coils in parallel;   a second heat exchanger to exchange heat between the working fluid and a second process fluid,   a reversing valve configured to change a flow direction of the working fluid through the first heat exchanger; and   a plurality of valves configured to direct the working fluid through the plurality of heat exchange coils of the first heat exchanger based on the flow direction of the working fluid through the first heat exchanger,   wherein the working fluid flows through the plurality of heat exchange coils in series when the flow direction is a first direction, and the working fluid flows through the plurality of heat exchange coils in parallel when the flow direction is a second direction.   
     
     
         2 . The heat transfer circuit of  claim 1 , wherein
 the first mode is a cooling mode in which the first heat exchanger operates as a condenser that heats the first process fluid with the working fluid,   the second mode is a heat pump mode in which the first heat exchanger operates as an evaporator that cools the second process fluid with the working fluid.   
     
     
         3 . The heat transfer circuit of  claim 1 , wherein the plurality of valves includes a valve blocking the working fluid in the first mode and allowing working fluid to pass through in the second mode. 
     
     
         4 . The heat transfer circuit of  claim 3 , wherein the valve blocks the working fluid in the first mode to prevent the working fluid from bypassing at least one of the plurality of heat exchange coils. 
     
     
         5 . The heat transfer circuit of  claim 1 , further comprising:
 a reversible main flow path for the working fluid that extends from the reversible valve through the first heat exchanger, the expander, and the second heat exchanger, and the reversible main flow path including two or more branches that direct the working fluid through the plurality of heat exchange coils.   
     
     
         6 . The heat transfer circuit of  claim 5 , wherein the reversible main flow path splits into the two or more branches between the reversible valve and the first heat exchanger, the two or more branches converging back into the reversible main flow path between the first heat exchanger and the expander. 
     
     
         7 . The heat transfer circuit of  claim 6 , wherein the two or more branches include a first branch and a second branch, the plurality of heat exchange coils including a first heat exchange coil that fluidly connects the first branch and the second branch. 
     
     
         8 . The heat transfer circuit of  claim 5 , wherein the plurality of valves including a first valve and a second valve, and the two or more branches include a first branch including the first valve and a second branch including the second valve. 
     
     
         9 . The heat transfer circuit of  claim 5 , wherein the plurality of heat exchange coils includes a first heat exchange coil, and the two or more branches include a first branch that includes the first heat exchange coil. 
     
     
         10 . The heat transfer circuit of  claim 1 , wherein the plurality of valves includes two or more check valves. 
     
     
         11 . The heat transfer circuit of  claim 1 , wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, a flow direction of the working fluid through the first heat exchange coil changes from the first mode to the second mode. 
     
     
         12 . The heat transfer circuit of  claim 1 , wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, a flow direction of the working fluid through the first heat exchange coil is same in the first mode and the second mode. 
     
     
         13 . The heat transfer circuit of  claim 1 , wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, the working fluid and the first process fluid in the first heat exchange coil in counter-flow in the first mode. 
     
     
         14 . A method of operating a heat transfer circuit, comprising:
 operating in a first mode by:
 compressing a working fluid in a compressor, 
 directing the working fluid through a first heat exchanger, expander, and a second heat exchanger in a first direction, the first heat exchanger including a plurality of heat exchange coils, a process fluid flowing through the heat exchange coils of the first heat exchanger in parallel, wherein directing the working fluid through the first heat exchanger in the first direction includes directing the working fluid through the plurality of heat exchange coils of the heat exchanger in series; and 
   operating in a second mode by:
 compressing the working fluid in a compressor, and 
 directing the working fluid through the first heat exchanger, the expander, and the second heat exchanger in a second direction, wherein directing the working fluid through the first heat exchanger in the second direction includes directing the working fluid through the plurality of heat exchange coils of the heat exchanger in parallel. 
   
     
     
         15 . The method of  claim 14 , wherein
 the first mode is a cooling mode that includes heating the first process fluid in the first heat exchanger with the working fluid and cooling the second process fluid in the second heat exchanger with the working fluid,   the second mode is a heat pump mode that includes cooling the first process fluid in the first heat exchanger with the working fluid and heating the second process fluid in the second heat exchanger with the working fluid.   
     
     
         16 . The method of  claim 14 , wherein
 operating in the first mode includes positioning a reversing valve in a first position, the first position directing the working fluid after being compressed in the compressor in the first direction through the first direction through the first heat exchanger, expander, and a second heat exchanger,   operating in the second mode includes positioning the reversing valve in a second position, the second position directing the working fluid after being compressed in the compressor in the second direction through the first heat exchanger, expander, and a second heat exchanger.