Multi-compartment transport refrigeration system with economizer

Abstract

A multi-compartment transport refrigeration system includes a compressor having suction port, discharge port and intermediate inlet port; a heat rejecting heat exchanger; an economizer heat exchanger having a first refrigerant flow path and a second refrigerant flow path therethrough; a first evaporator expansion device; a first evaporator having an inlet coupled to the first evaporator expansion device and an outlet coupled to a compressor inlet path, the first evaporator for cooling a first compartment of a container; a second evaporator expansion; a second evaporator having an inlet coupled to the second evaporator expansion device, the second evaporator for cooling a second compartment of the container; an economizer expansion device coupled to the first refrigerant flow path, the economizer expansion device directing refrigerant from the first refrigerant flow path to the second refrigerant flow path, the second refrigerant flow path coupled to the intermediate inlet port.

1 . A multi-compartment transport refrigeration system comprising:
 a compressor having a suction port, a discharge port and an intermediate inlet port located at an intermediate location along a compression path between the compressor suction port and the compressor discharge port;   a heat rejecting heat exchanger downstream of the compressor discharge port;   an economizer heat exchanger having a first refrigerant flow path and a second refrigerant flow path therethrough;   a first evaporator expansion device downstream of the first refrigerant flow path;   a first evaporator having an inlet coupled to the first evaporator expansion device and an outlet coupled to a compressor inlet path, the compressor inlet path coupled to the compressor suction port, the first evaporator for cooling a first compartment of a container;   a second evaporator expansion device downstream of the first refrigerant flow path;   a second evaporator having an inlet coupled to the second evaporator expansion device and an outlet coupled to the compressor inlet path, the second evaporator for cooling a second compartment of the container; and   an economizer expansion device coupled to the first refrigerant flow path, the economizer expansion device directing refrigerant from the first refrigerant flow path to the second refrigerant flow path, the second refrigerant flow path coupled to the intermediate inlet port.   
     
     
         2 . The multi-compartment transport refrigeration system of  claim 1  further comprising:
 a controller configured to control the economizer expansion device to regulate flow of refrigerant along the second refrigerant flow path to the intermediate inlet port. 
 
     
     
         3 . The multi-compartment transport refrigeration system of  claim 2  wherein:
 the controller is configured to control the economizer expansion device in response to an operating parameter of the refrigeration system. 
 
     
     
         4 . The multi-compartment transport refrigeration system of  claim 3  wherein:
 the controller is configured to control the economizer expansion device in response to superheat of the economizer heat exchanger. 
 
     
     
         5 . The multi-compartment transport refrigeration system of  claim 2  further comprising:
 an engine to provide power to the compressor; 
 wherein the controller is configured to control the economizer expansion device in response to an operating parameter of the engine. 
 
     
     
         6 . The multi-compartment transport refrigeration system of  claim 2  wherein:
 the controller is configured to control the economizer expansion device in response to a refrigeration system loading event. 
 
     
     
         7 . The multi-compartment transport refrigeration system of  claim 2  wherein:
 the controller is configured to control the economizer expansion device in response to a pulsed control signal applied to one of the first evaporator expansion device and the second evaporator expansion device. 
 
     
     
         8 . The multi-compartment transport refrigeration system of  claim 7  wherein:
 the pulsed control signal is a pulse width modulation signal. 
 
     
     
         9 . The multi-compartment transport refrigeration system of  claim 2  wherein:
 the controller is configured to control the economizer expansion device in response to an electrical parameter of the refrigeration system. 
 
     
     
         10 . The multi-compartment transport refrigeration system of  claim 9  wherein:
 the electrical parameter of the refrigeration system includes one or more of output current of a generator, output voltage of a generator, current draw of the compressor, input voltage at the compressor, current draw of a heat rejecting heat exchanger fans, input voltage at the heat rejecting heat exchanger fan, current draw of an evaporator fan, input voltage at the evaporator fans, current draw of a heater and input voltage at the heater. 
 
     
     
         11 . The multi-compartment transport refrigeration system of  claim 9  wherein:
 control of the economizer expansion device in response to the electrical parameter of the refrigeration system includes: 
 comparing the electrical parameter to a limit; 
 operating the economizer expansion device in a full economized mode when the electrical parameter does not exceed the limit; and 
 operating the economizer expansion device in a limited economized mode when the electrical parameter does exceed the limit. 
 
     
     
         12 . A transport refrigeration system comprising:
 a compressor having a suction port, a discharge port and an intermediate inlet port located at an intermediate location along a compression path between the compressor suction port and the compressor discharge port;   a heat rejecting heat exchanger downstream of the compressor discharge port;   an economizer heat exchanger having a first refrigerant flow path and a second refrigerant flow path therethrough;   an evaporator expansion device downstream of the first refrigerant flow path;   an evaporator having an inlet coupled to the evaporator expansion device and an outlet coupled to a compressor inlet path, the compressor inlet path coupled to the compressor suction port, the evaporator for cooling a compartment of a container;   an economizer expansion device coupled to the first refrigerant flow path, the economizer expansion device directing refrigerant from the first refrigerant flow path to the second refrigerant flow path, the second refrigerant flow path coupled to the intermediate inlet port; and   a controller configured to control the economizer expansion device to regulate flow of refrigerant along the second refrigerant flow path to the intermediate inlet port, the controller configured to control the economizer expansion device in response to an electrical parameter of the refrigeration system.   
     
     
         13 . The transport refrigeration system of  claim 12  wherein:
 the electrical parameter of the refrigeration system includes one or more of output current of a generator, output voltage of a generator, current draw of the compressor, input voltage at the compressor, current draw of a heat rejecting heat exchanger fans, input voltage at the heat rejecting heat exchanger fan, current draw of an evaporator fan, input voltage at the evaporator fans, current draw of a heater and input voltage at the heater. 
 
     
     
         14 . The transport refrigeration system of  claim 12  wherein:
 control of the economizer expansion device in response to the electrical parameter of the refrigeration system includes: 
 comparing the electrical parameter to a limit; 
 operating the economizer expansion device in a full economized mode when the electrical parameter does not exceed the limit; and 
 operating the economizer expansion device in a limited economized mode when the electrical parameter does exceed the limit.