Transportation refrigeration system having multiple fans

Abstract

A transportation refrigeration system includes a refrigeration circuit that includes a compressor, a condenser, a first heat exchanger and a second heat exchanger. A first variable speed fan is associated with the first heat exchanger and a second variable speed fan is associated the second heat exchanger.

What is claimed is: 
     
         1 . A transportation refrigeration system comprising:
 a refrigeration circuit including a compressor, a condenser, a first heat exchanger, and a second heat exchanger, wherein a first variable speed fan is associated with the first heat exchanger and a second variable speed fan is associated the second heat exchanger.   
     
     
         2 . The transportation refrigeration system of  claim 1 , wherein the first variable speed fan operates independently of the second variable speed fan. 
     
     
         3 . The transportation refrigeration system of  claim 1 , further comprising a first compartment passageway having a first compartment passageway inlet located upstream of the first heat exchanger and the first variable speed fan located downstream of the first heat exchanger. 
     
     
         4 . The transportation refrigeration system of  claim 3 , including a first nozzle downstream of the first variable speed fan having a first compartment outlet. 
     
     
         5 . The transportation refrigeration system of  claim 4 , further comprising a second compartment passageway having a second compartment passageway inlet located upstream of the second heat exchanger and a second variable speed fan located downstream of the second heat exchanger. 
     
     
         6 . The transportation refrigeration system of  claim 5 , including a second nozzle downstream of the second variable speed fan having a second compartment outlet. 
     
     
         7 . The transportation refrigeration system of  claim 6 , wherein the first compartment outlet is spaced from the second compartment outlet. 
     
     
         8 . The transportation refrigeration system of  claim 7 , wherein the first variable speed fan includes a plurality of first variable speed fans. 
     
     
         9 . The transportation refrigeration system of  claim 8 , wherein the second variable speed fan includes a plurality of second variable speed fans. 
     
     
         10 . The transportation refrigeration system of  claim 1 , wherein the first heat exchanger is in parallel to the second heat exchanger. 
     
     
         11 . The transportation refrigeration system of  claim 10 , further comprising a first expansion device upstream of the first heat exchanger. 
     
     
         12 . The transportation refrigeration system of  claim 11 , wherein the first expansion device is a first electronically controlled expansion valve and a controller is configured to control refrigerant flow to the first heat exchanger by controlling the first electronically controlled expansion valve. 
     
     
         13 . The transportation refrigeration system of  claim 12 , further comprising a second expansion device upstream of the second heat exchanger. 
     
     
         14 . The transportation refrigeration system of  claim 13 , and the second expansion device is a second electronically controlled expansion valve and the controller is configured to control refrigerant flow to the second heat exchanger by controlling the second electronically controlled expansion valve. 
     
     
         15 . A method of operating a refrigeration cycle comprising the steps of:
 conditioning a first compartment in a cargo space a first heat exchanger by operating a first variable speed fan at a first speed; and   conditioning a second compartment in the cargo space a second heat exchanger by operating a second variable speed fan at a second speed; wherein the first speed is different from the second speed.   
     
     
         16 . The method of  claim 15 , wherein operating the first variable speed fan includes drawing air from the first compartment into a first compartment passageway inlet, over the first heat exchanger and through a first nozzle having a first compartment passageway outlet. 
     
     
         17 . The method of  claim 16 , wherein operating the second variable speed fan includes drawing air from the second compartment into a second compartment passageway inlet, over the second heat exchanger and through a second nozzle having a second compartment passageway outlet spaced from the first compartment passageway outlet. 
     
     
         18 . The method of  claim 15 , further comprising:
 controlling refrigerant flow through a first electronically controlled expansion valve upstream of the first heat exchanger with a controller in electrical communication with the first electronically controlled expansion valve.   
     
     
         19 . The method of  claim 18 , further comprising:
 controlling refrigerant flow through a second electronically controlled expansion valve upstream of the second heat exchanger with a controller in electrical communication with the second electronically controlled expansion valve.   
     
     
         20 . The method of  claim 15 , further comprising:
 operating the first variable speed fan at a first maximum flow rate; and   operating a second variable speed fan at a second maximum flow rate that is less than the first maximum flow rate.