Electrochemical cell cooling system

Abstract

An electrochemical cell cooling system includes a closed loop for circulating coolant through an electrochemical cell. The loop includes a pump for pumping the coolant from a container through a filter and a heat exchanger. Pressure in the container and loop is selectively adjusted upwardly for a positive pressure condition or downwardly for a negative pressure condition using a pressure-adjusting flow line. The flow line includes a venturi in fluid communication with the container and a shut-off valve downstream of the venturi which is opened to induce depressurization of the loop or closed to cause pressurization. A variable-flow valve upstream of the venturi enables fine adjustment of the pressurization or depressurization. Alternatively, a flow-restricted bypass and a second variable-flow valve can be introduced to facilitate coolant temperature control.

1 . A system for cooling an electrochemical cell, the system comprising: 
 a) a coolant circulation loop for supplying a coolant to an electrochemical cell for absorbing heat from the cell, the coolant circulation loop having: 
 a coolant container;  
 a pump for circulating the coolant through the coolant circulation loop; and  
 a heat exchanging portion for cooling the coolant; and  
   b) a pressure-adjusting flow line having a pressure-adjustment device in fluid communication with the coolant container for selectively increasing or decreasing fluid pressure in the container thereby selectively enabling either positive-pressure cooling or negative-pressure cooling of the electrochemical cell.    
   
   
       2 . The system as claimed in  claim 1  wherein the pressure adjustment device is a venturi.  
   
   
       3 . The system as claimed in  claim 2  wherein the pressure-adjusting flow line further comprises a valve disposed downstream of the venturi, the valve being operable between an open position, in which fluid exhausts to atmosphere through the venturi, thus inducing a depressurization in the coolant container, and a closed position, in which fluid is forced to vent through a bottom port of the venturi into the coolant container, thus causing a pressurization of the coolant container.  
   
   
       4 . The system as claimed in  claim 3  wherein the pressure-adjusting flow line further comprises a shut-off valve disposed downstream of the venturi and operable between an open position permitting fluid to exhaust to atmosphere, thus inducing a depressurization of the coolant container, and a closed position, wherein fluid is forced to vent into the container, thus causing a pressurization of the coolant container.  
   
   
       5 . The system as claimed in  claim 4  wherein the shut-off valve is a solenoid valve.  
   
   
       6 . The system as claimed in  claim 4  wherein the pressure-adjusting flow line further comprises a variable-flow valve disposed upstream of the venturi and operable to variably throttle the fluid flow passing through the flow line, thereby finely adjusting the pressurization or depressurization of the coolant container.  
   
   
       7 . The system as claimed in  claim 6  wherein the pressure-adjusting flow line further comprises a fluid supply exhausting to atmosphere through the variable valve, pressure-adjustment device and shut-off valve.  
   
   
       8 . The system as claimed in  claim 7  wherein the fluid flowing in the pressure-adjusting flow line is an inert gas.  
   
   
       9 . The system as claimed in  claim 8  wherein the inert gas is nitrogen.  
   
   
       10 . The system as claimed in  claim 1  wherein the heat exchanging portion is a heat exchanger.  
   
   
       11 . The system as claimed in  claim 9  wherein the coolant circulation loop further comprises a filter.  
   
   
       12 . The system as claimed in  claim 1  wherein the coolant circulation loop further comprises a bypass line that bypasses the electrochemical cell from a bypass point upstream of the electrochemical cell, thus dividing the coolant circulation loop into an inner bypass loop and an outer loop.  
   
   
       13 . The system as claimed in  claim 12  wherein the bypass line comprises a flow constriction.  
   
   
       14 . The system as claimed in  claim 13  wherein the outer loop comprises a second variable-flow valve disposed between the bypass point and the electrochemical cell.  
   
   
       15 . A method of cooling an electrochemical cell, the method comprising the steps of: 
 circulating a coolant through a loop that includes the electrochemical cell and a coolant container;    flowing a fluid through a pressure-adjusting flow path in fluid communication with the container for selectively increasing or decreasing pressure in the container and thus in the loop.    
   
   
       16 . The method as claimed in  claim 15  wherein the step of flowing the fluid through the pressure-adjusting flow path comprises the step of flowing the fluid through a venturi.  
   
   
       17 . The method as claimed in  claim 16  further comprising the step of selectively operating a shut-off valve downstream of the venturi, whereby the valve is operated between an open position permitting fluid to exhaust to atmosphere, thus inducing a depressurization of the coolant container, and a closed position, wherein fluid is forced to vent into the container, thus causing a pressurization of the coolant container.  
   
   
       18 . The method as claimed in  claim 17  further comprising the step of variably adjusting a variable-flow valve disposed upstream of the venturi, thereby finely adjusting the pressurization or depressurization of the coolant container.  
   
   
       19 . The method as claimed in  claim 18  further comprising the step of partially bypassing the electrochemical cell whereby a portion of the coolant flows through a bypass while a remainder of the coolant flows through the electrochemical cell.  
   
   
       20 . The method as claimed in  claim 19  wherein the step of partially bypassing the electrochemical cell comprises the step of constricting coolant flow through the bypass.  
   
   
       21 . The method as claimed in  claim 20  wherein the step of partially bypassing the electrochemical cell further comprises the step of throttling coolant flow with a variable-flow valve disposed between a bypass point and the electrochemical cell.  
   
   
       22 . The method as claimed in  claim 21  further comprising the step of filtering the coolant.  
   
   
       23 . A system for cooling an electrochemical cell, the system comprising: 
 a) a coolant circulation loop for supplying a coolant to an electrochemical cell for absorbing heat from the cell, the coolant circulation loop having: 
 a coolant container;  
 a pump for circulating the coolant through the coolant circulation loop; and  
 a heat exchanger for cooling the coolant; and  
   b) a pressure-adjusting flow line having: 
 a venturi in fluid communication with the coolant container for selectively increasing or decreasing fluid pressure in the container; and  
 a valve downstream of the venturi, the valve adapted to be opened to depressurize the coolant circulation loop or to be closed to pressurize the coolant circulation loop.  
   
   
   
       24 . The system as claimed in  claim 23  wherein the pressure-adjusting flow line further comprises a variable valve disposed upstream of the venturi to vary a flow rate of fluid through the venturi.  
   
   
       25 . The system as claimed in  claim 24  further comprising a pressure controller for controlling the variable valve in response to a pressure feedback signal from a pressure transducer in the coolant circulation loop.  
   
   
       26 . The system as claimed in  claim 24  further comprising a temperature controller for controlling a cooling rate of the heat exchanger in response to a temperature feedback signal from a temperature sensor in the coolant circulation loop.  
   
   
       27 . The system as claimed in  claim 25  further comprising a temperature controller for controlling a cooling rate of the heat exchanger in response to a temperature feedback signal from a temperature sensor in the coolant circulation loop.  
   
   
       28 . The system as claimed in  claim 27  wherein the pressure controller and temperature controller are both PID controllers adapted to receive pressure and temperature setpoints, respectively, for comparison with the pressure and temperature feedback signals, respectively.