Free cooling refrigeration system

Abstract

A refrigeration system includes a chiller with an integrated free cooling system and refrigeration system. In certain embodiments, the chiller may be a single package unit with all equipment housed within the same support frame. The chiller may generally include three modes of operation: a first mode that employs free cooling, a second mode that employs free cooling and implements a refrigeration cycle, and a third mode that uses the free cooling system to remove heat from the refrigeration system. A heat exchanger may be shared between the free cooling system and the refrigeration system to transfer heat from the refrigeration system to the free cooling system.

1 . A refrigeration system comprising:
 a free cooling system configured to exchange heat between a cooling fluid and ambient air; and   a heat exchanger configured to receive refrigerant and to transfer heat from the refrigerant to the cooling fluid.   
     
     
         2 . The refrigeration system of  claim 1 , wherein the heat exchanger is disposed within a high pressure side of a vapor-compression refrigeration system. 
     
     
         3 . The refrigeration system of  claim 1 , comprising a first refrigeration system configured to implement a vapor-compression cycle with the refrigerant. 
     
     
         4 . The refrigeration system of  claim 3 , wherein the first refrigeration system comprises:
 a compressor configured to compress the refrigerant;   a condenser configured to receive and to condense the compressed refrigerant;   an expansion device configured to reduce pressure of the condensed refrigerant; and   an evaporator configured to evaporate the refrigerant by absorbing heat from the cooling fluid prior to returning the refrigerant to the compressor.   
     
     
         5 . The refrigeration system of  claim 4 , wherein heat exchanger is configured to condense or subcool the refrigerant exiting the condenser or to desuperheat the compressed refrigerant prior to the refrigerant entering the condenser. 
     
     
         6 . The refrigeration system of  claim 1 , comprising an additional heat exchanger configured to receive the refrigerant and transfer heat to the cooling fluid, wherein the heat exchanger is configured to partially condense the refrigerant and the additional heat exchanger is configured to subcool the refrigerant. 
     
     
         7 . The refrigeration system of  claim 1 , wherein the free cooling system comprises an air-to-liquid heat exchanger configured to transfer heat from the cooling fluid to the ambient air. 
     
     
         8 . The refrigeration system of  claim 1 , comprising at least one valve configured selectively to bypass the free cooling system and to direct the cooling fluid to the free cooling system before the cooling fluid enters an evaporator in fluid communication with the refrigerant. 
     
     
         9 . The refrigeration system of  claim 1 , wherein the free cooling system comprises one or more valves defining a first circuit and a second circuit, and wherein the first circuit is configured to circulate the cooling fluid between a cooling loop and an air-to-liquid heat exchanger in fluid communication with the ambient air, and the second circuit is configured to circulate the cooling fluid between the heat exchanger and the air-to-liquid heat exchanger. 
     
     
         10 . A refrigeration system comprising:
 a vapor-compression refrigeration system comprising an evaporator configured to remove heat from a cooling fluid circulating through a cooling loop;   a free cooling system configured to circulate the cooling fluid through a first circuit to exchange heat between the cooling fluid and ambient air without implementing a vapor-compression cycle; and   a second circuit disposed in the free cooling system and configured to circulate an isolated portion of the cooling fluid through a heat exchanger common to the vapor-compression refrigeration system and the free cooling system.   
     
     
         11 . The refrigeration system of  claim 10 , wherein the refrigeration system is disposed within a common support frame. 
     
     
         12 . The refrigeration system of  claim 10 , wherein the cooling fluid comprises water, a brine solution, or a glycol solution. 
     
     
         13 . The refrigeration system of  claim 10 , wherein the vapor-compression refrigeration system includes a condenser and the heat exchanger is configured to supplement the condenser by desuperheating, subcooling, or partially condensing refrigerant flowing within the vapor-compression refrigeration system. 
     
     
         14 . The refrigeration system of  claim 10 , wherein the free cooling system includes an air-to-liquid heat exchanger configured to receive the cooling fluid from the first circuit and the second circuit and to remove heat from the cooling fluid. 
     
     
         15 . The refrigeration system of  claim 14 , wherein the vapor-compression refrigeration system includes a condenser, and wherein the condenser and the air-to-liquid heat exchanger comprise multichannel heat exchangers configured to share a common fan. 
     
     
         16 . The refrigeration system of  claim 10 , comprising a controller configured to direct the cooling fluid through the first circuit or through the second circuit based on a sensed temperature of the ambient air. 
     
     
         17 . The refrigeration system of  claim 10 , comprising one or more valves or pumps configured selectively to direct the cooling fluid through the first or second circuit. 
     
     
         18 . A method for operating a refrigeration system, comprising:
 operating a vapor-compression refrigeration system to remove heat from a cooling fluid; and   circulating an isolated portion of the cooling fluid within a free cooling system to remove heat from the vapor-compression refrigeration system.   
     
     
         19 . The method of  claim 18 , comprising circulating the cooling fluid to an air-to-liquid heat exchanger within the free cooling system to remove heat from the cooling fluid. 
     
     
         20 . The method of  claim 18 , comprising selecting a mode of operation for the refrigeration system based on a sensed temperature of ambient air, wherein the circulating an isolated portion of the cooling fluid comprises a first mode of operation and wherein removing heat from the free cooling system without implementing a vapor-compression cycle comprises a second mode of operation. 
     
     
         21 . The method of  claim 18 , comprising exchanging energy between the cooling fluid and a refrigerant within the vapor-compression refrigeration system to partially condense or desuperheat the refrigerant.