Refrigeration system with separate feedstreams to multiple evaporator zones

Abstract

A refrigeration system has: (a) a fluid tight circulation loop including a compressor, a condenser and an evaporator, the evaporator having at least three evaporator zones, each evaporator zone having an inlet port, the circulation loop being further configured to measure the condition of the refrigerant with a refrigerant condition sensor disposed within the evaporator upstream of the evaporator outlet port; and control the flow of refrigerant to the evaporator based upon the measured condition of the refrigerant within the evaporator, and (b) a controller for controlling the flow rate of refrigerant to the evaporator based upon the measured condition of the refrigerant within the evaporator upstream of the evaporator outlet port.

What is claimed is: 
     
         1 . A method of controlling a refrigeration system, wherein the refrigeration system comprises a refrigerant disposed within a fluid-tight circulation loop including a compressor, a condenser and an evaporator, the refrigerant being capable of existing in a liquefied state, a gaseous state and a two-phase state comprising both refrigerant in the liquefied state and refrigerant in the gaseous state, the evaporator having an outlet port and multiple evaporator zones in series, each evaporator zone having an evaporator zone inlet port, the method comprising the steps of:
 (a) compressing refrigerant in a gaseous state within the compressor and cooling the refrigerant within the condenser to yield refrigerant in the liquefied state;   (b) flowing refrigerant from the condenser into the evaporator via the inlet ports of each evaporator zone, wherein the refrigerant partially exists in a two-phase state; and   (c) flowing refrigerant from the evaporator to the compressor.   
     
     
         2 . The method of  claim 1  wherein the multiple zones in the evaporator are provided by a continuous length of tubing. 
     
     
         3 . The method of  claim 2  wherein the continuous length of tubing continually and smoothly expands from the inlet port of the most upstream evaporator zone to the outlet port of the evaporator. 
     
     
         4 . The method of  claim 1  wherein the measuring of the refrigerant condition in step (e) is carried out with a plurality of refrigerant condition sensors. 
     
     
         5 . The method of  claim 1  further comprising step d) measuring the condition of the refrigerant with a refrigerant condition sensor disposed within the evaporator upstream of the outlet port, wherein the measuring of the refrigerant condition is carried out with a refrigerant condition sensor disposed within each of the evaporator zones. 
     
     
         6 . The method of  claim 5 , further comprising step e) controlling the flow rate of refrigerant to the evaporator in step b) based upon the measured condition of the refrigerant condition of the refrigerant from step d), wherein the controlling of the refrigerant flow rate to the evaporator is carried out by controlling the refrigerant flow rate to each of the evaporator zones with a separate controller. 
     
     
         7 . The method of  claim 1  wherein the flowing of refrigerant from the condenser into the evaporator in step (b) is carried out after cooling the refrigerant in a precooler disposed downstream of the condenser and upstream of the evaporator. 
     
     
         8 . The method of  claim 1  wherein the flowing of refrigerant from the condenser into the evaporator in step (b) is carried out after cooling the refrigerant by thermal contact with evaporating refrigerant in a precooler disposed downstream of the condenser and upstream of the evaporator thermal contact with evaporating refrigerant. 
     
     
         9 . The method of  claim 1  comprising the additional step of flowing a portion of the refrigerant exiting the evaporator to the inlet port of each of the evaporator zones. 
     
     
         10 . The method of  claim 1  comprising the additional step of flowing a portion of the refrigerant exiting the evaporator to the inlet port of each of the evaporator zones via a vapor booster operated to maintain two phase refrigerant volume in the evaporator at equilibrium with evaporator respective internal volume under all loading conditions. 
     
     
         11 . The method of  claim 1  wherein the condenser has a plurality of condenser zones, each condenser zone having a condenser zone inlet port. 
     
     
         12 . A refrigeration system comprising:
 (a) a fluid tight circulation loop including a compressor, a condenser and an evaporator, the circulating loop being configured to continuously circulate a refrigerant which is capable of existing in a liquefied state, a gaseous state and a two-phase state comprising both refrigerant in the liquefied state and refrigerant in the gaseous state, the evaporator having an outlet port and multiple evaporator zones in series, each evaporator zone having an inlet port, the circulation loop being further configured to (i) compress refrigerant in a gaseous state within the compressor and cool the refrigerant within the condenser to yield refrigerant in the liquefied state; (ii) flow refrigerant from the condenser into the evaporator via the inlet ports of each evaporator zone, wherein the refrigerant partially exists in a two-phase state; (iii) flow refrigerant from the evaporator to the compressor; and   (b) a controller for controlling the flow rate of refrigerant to the evaporator based upon the measured condition of the refrigerant within the evaporator upstream of the evaporator outlet port.   
     
     
         13 . The refrigeration system of  claim 12  wherein the at multiple zones in the evaporator are provided by a continuous length of tubing. 
     
     
         14 . The refrigeration system of  claim 13  wherein the continuous length of tubing continually and smoothly expands from the inlet port of the most upstream evaporator zone to the outlet port of the evaporator. 
     
     
         15 . The refrigeration system of  claim 12  wherein the measuring of the refrigerant condition in the function described in (a)(v) is carried out with a plurality of refrigerant condition sensors. 
     
     
         16 . The refrigeration system of  claim 12  wherein the measuring of the refrigerant condition in the function described in (a)(v) is carried out with a refrigerant condition sensor disposed within each of the evaporator zones. 
     
     
         17 . The refrigeration system of  claim 16  wherein the controlling of the refrigerant flow rate to the evaporator in the function described in (a)(vi) is carried out by controlling the refrigerant flow rate to each of the evaporator zones with a separate controller. 
     
     
         18 . The refrigeration system of  claim 12  further comprising a precooler disposed downstream of the condenser and upstream of the evaporator, and wherein the flowing of refrigerant from the condenser into the evaporator in the function described in (a)(ii) is carried out after cooling the refrigerant in the precooler. 
     
     
         19 . The refrigeration system of  claim 12  further comprising recycling conduits for flowing a portion of the refrigerant exiting the evaporator to the inlet port of each of the evaporator zones. 
     
     
         20 . The refrigeration system of  claim 19  comprising a vapor pressure booster capable of maintaining two phase refrigerant in the evaporator at equilibrium under all loading conditions.