Condenser/Accumulator and Systems and Operation Methods

Abstract

A condenser/accumulator ( 60 ) has a shell ( 62 ). A coolant flowpath extends from a coolant ( 144 ) inlet to a coolant outlet ( 146 ). An upper tube bundle ( 68 ) is within the shell, a first branch of the coolant flowpath passing through tubes of the upper tube bundle. A lower tube bundle ( 70 ) is within the shell, a second branch of the coolant flowpath passing through tubes of the lower tube bundle. A refrigerant flowpath extends from a refrigerant inlet ( 64 ) to a refrigerant outlet ( 66 ) and is in heat transfer relation with the coolant flowpath. There is a vertical gap ( 76 ) between the upper tube bundle and the lower tube bundle and comprising at least 50% of a free volume of a refrigerant space within the shell.

1 . A condenser/accumulator ( 60 ) comprising:
 a shell ( 62 );   a coolant flowpath extending from a coolant ( 144 ) inlet to a coolant outlet ( 146 );   an upper tube bundle ( 68 ) within the shell, a first branch ( 200 - 1 ) of the coolant flowpath passing through tubes of the upper tube bundle;   a lower tube bundle ( 70 ) within the shell, a second branch ( 200 - 2 ) of the coolant flowpath passing through tubes of the lower tube bundle;   a refrigerant flowpath extending from a refrigerant inlet ( 64 ) to a refrigerant outlet ( 66 ) and in heat transfer relation with the coolant flowpath; and   a vertical gap ( 76 ) between the upper tube bundle and the lower tube bundle and comprising at least 50% of a free volume of a refrigerant space within the shell   
     
     
         2 . The condenser/accumulator of  claim 1  wherein:
 the first branch is in parallel to the second branch, re-joining to pass through remaining tubes of the upper tube bundle. 
 
     
     
         3 . The condenser/accumulator of  claim 1  wherein:
 the vertical gap comprises 60-80% of the free volume. 
 
     
     
         4 . The condenser/accumulator of  claim 1  wherein:
 a vertical height (H 1 ) of the gap is at least 50% of a characteristic internal radius (R 1 ) of the shell. 
 
     
     
         5 . The condenser/accumulator of  claim 1  wherein:
 a vertical height of the gap is 80-120% of a characteristic internal radius (R 1 ) of the shell. 
 
     
     
         6 . The condenser/accumulator of  claim 1  wherein:
 a refrigerant volume below the upper tube bundle and outside of a subcooling chamber around the lower tube bundle represents 50%-80% of a total free volume of the refrigerant space. 
 
     
     
         7 . The condenser/accumulator of  claim 1  wherein:
 the lower tube bundle is within a subcooler chamber having refrigerant inlet ports and having a refrigerant outlet port positioned upstream of the refrigerant outlet. 
 
     
     
         8 . The condenser/accumulator of  claim 1  wherein:
 the coolant inlet and coolant outlet are on a first end dome. 
 
     
     
         9 . The condenser/accumulator of  claim 1  wherein the shell comprises:
 a circular cylindrical tubular body; and 
 a pair of end plates forming bolting flanges. 
 
     
     
         10 . A cooling system comprising:
 the condenser/accumulator of  claim 1 ;   a pump coupled to the refrigerant outlet of the condenser/accumulator; and   a heat exchanger having a refrigerant inlet coupled to the pump and a refrigerant outlet coupled to the refrigerant inlet of the condenser/accumulator.   
     
     
         11 . The system of  claim 10  wherein:
 a fan is positioned to drive an airflow across the heat exchanger. 
 
     
     
         12 . The system of  claim 10  wherein:
 there are a plurality of said heat exchangers coupled in parallel to a single said condenser/accumulator; and there are an associated plurality of said fans respectively associated with said heat exchangers. 
 
     
     
         13 . The system of  claim 10  wherein:
 a refrigerant charge comprises at least 50% carbon dioxide by weight. 
 
     
     
         14 . The system of  claim 10  further comprising:
 a chiller ( 22 ) coupled to the coolant inlet to the coolant outlet so that the coolant flowpath is along a coolant loop ( 24 ,  26 ) of the chiller. 
 
     
     
         15 . A method for operating the system of  claim 10 , the method comprising running the pump to:
 draw into the pump and discharge from the pump a flow of the refrigerant as supercooled liquid;   pass the flow of the refrigerant through the heat exchanger where it draws heat from an external flow and becomes vapor; and   pass the flow of the refrigerant to the condenser/accumulator wherein the flow of the refrigerant discharges heat to the coolant and condenses back to liquid.   
     
     
         16 . A method for operating the system of  claim 10 , the method comprising:
 operating in a first condition wherein a surface of a liquid accumulation of the refrigerant in the vessel is within the gap;   operating in a second condition, at higher cooling load than the first condition, wherein the surface of the liquid accumulation of the refrigerant in the vessel is also within the gap but higher than in the first condition; and   shutting down the pump to go into a third condition wherein the surface of the liquid accumulation of the refrigerant in the vessel is above the gap.   
     
     
         17 . The method of  claim 16  wherein:
 a buildup of the liquid accumulation between the first condition and the second condition is at least 30% of a free internal volume of the vessel; and 
 a buildup of the liquid accumulation between the first condition and the third condition is at least 150% of the buildup of the liquid accumulation between the first condition and the second condition. 
 
     
     
         18 . A method for operating a cooling system, the cooling system comprising:
 a condenser/accumulator ( 60 ) having a coolant flowpath and a refrigerant flowpath;   a refrigerant-air heat exchanger ( 32 ) along the refrigerant flowpath; and   a pump ( 38 ) along the refrigerant flowpath downstream of the condenser/accumulator and upstream of the refrigerant-air heat exchanger, the method comprising:
 operating in a first condition wherein a surface of a liquid accumulation of the refrigerant within the condenser/accumulator is at a first level; 
 operating in a second condition, at higher cooling load than the first condition, wherein the surface of the liquid accumulation is at a second level higher than the first level; and 
 shutting down the pump to go into a third condition wherein the surface of the liquid accumulation is at a third level, higher than the second level. 
   
     
     
         19 . The method of  claim 18  wherein:
 the first level and the second level are below a condenser tube bundle and above a subcooler tube bundle; and 
 the third level is above at least a bottom of the condenser tube bundle. 
 
     
     
         20 . The condenser/accumulator of  claim 1  wherein:
 the upper tube bundle ( 68 ) comprises a first subgroup ( 68 - 1 ) and a second subgroup ( 68 - 2 ); 
 first ends of the first subgroup and first ends of the tubes of the lower tube bundle are open at an inlet plenum; and 
 first ends of the second subgroup are open at an outlet plenum, the first ends of the first subgroup and first ends of the second subgroup being proximate a first end of the shell.