Fluid based thermal conductivity control

Abstract

A temperature control system may include a compartment having at least one side with low thermal conductivity and a side with a double wall, the double wall having an interior wall and an exterior wall, the interior wall and the exterior wall having high thermal conductivity and forming a channel therebetween and a reservoir connected to the channel. A drive may be contained within the reservoir, wherein the drive is responsive to a temperature within the compartment to transfer a liquid with high thermal conductivity from the reservoir into the channel to increase thermal conductivity between the interior of the compartment and the exterior of the compartment, and allows a gas with low thermal conductivity to be present within the channel when the channel does not contain the liquid to decrease thermal conductivity between the interior of the compartment and the exterior of the compartment.

1 . A temperature control system, comprising:
 a compartment having an at least one side with low thermal conductivity and a side with a double wall, the side with the double wall having an interior wall adjacent to an interior of the compartment and an exterior wall, the interior wall and the exterior wall having high thermal conductivity and forming a channel therebetween;   a reservoir connected to the channel; and   a drive contained within the reservoir, wherein the drive is responsive to a temperature within the compartment to transfer a liquid with high thermal conductivity from the reservoir into the channel to increase thermal conductivity between the interior of the compartment and an exterior of the compartment and allows a gas with low thermal conductivity to be present within the channel when the channel does not contain the liquid to decrease thermal conductivity between the interior of the compartment and the exterior of the compartment.   
     
     
         2 . The temperature control system of  claim 1 , wherein the drive includes a piston and an actuator coupled to the piston, the actuator configured to move the piston to transfer the liquid or the gas into the channel. 
     
     
         3 . The temperature control system of  claim 2 , wherein the actuator includes a thermally activated bimetal actuator or a snap disk actuator in thermal communication with the compartment so as to move the piston in response to the temperature of the compartment. 
     
     
         4 . The temperature control system of  claim 2 , wherein the actuator includes a paraffin pellet in thermal communication with the compartment, the paraffin pellet configured to expand upon increase in temperature and contract upon decrease in temperature, the paraffin pellet configured so that the piston causes the liquid to be transferred into the channel when the paraffin pellet expands and causes the gas to be transferred into the channel when the paraffin pellet contracts. 
     
     
         5 . The temperature control system of  claim 2 , wherein the actuator includes a solenoid connected to a temperature sensor within the compartment so as to move the piston in response to the temperature of the compartment. 
     
     
         6 . The temperature control system of  claim 2 , wherein the actuator includes a fluid expansion actuator that communicates with the compartment through a temperature sense bulb so as to move the piston in response to the temperature of the compartment. 
     
     
         7 . The temperature control system of  claim 1 , further comprising:
 a vent tube that connects an upper part of the channel to a part of the reservoir containing only the gas.   
     
     
         8 . The temperature control system of  claim 1 , wherein the interior wall or the exterior wall includes at least one fin that protrudes into the channel. 
     
     
         9 . The temperature control system of  claim 1 , further comprising:
 a temperature sensor within the compartment that communicates with the drive.   
     
     
         10 . The temperature control system of  claim 1 , wherein the drive is a pump with a variable speed to transfer the liquid into the channel when increased thermal conductivity is desired. 
     
     
         11 . The temperature control system of  claim 10 , further comprising:
 a temperature sensor within the compartment that communicates with the pump to adjust the speed of the pump in response to the temperature of the compartment.   
     
     
         12 . The temperature control system of  claim 10 , wherein the channel is at least partially divided into at least two parts by a separator having high thermal conductivity. 
     
     
         13 . A method for controlling the temperature of a compartment containing power electronics, the method comprising:
 transferring a thermally conductive liquid from a reservoir into a channel that is adjacent to the compartment to increase the thermal conductivity between an interior of the compartment and an exterior of the compartment in response to a temperature within the compartment; and   allowing a gas having low thermal conductivity to flow into the channel to decrease the thermal conductivity between the interior of the compartment and the exterior of the compartment in response to the temperature within the compartment.   
     
     
         14 . The method of  claim 13 , wherein the thermally conductive liquid is transferred from the reservoir into the channel by a drive that is responsive to the temperature within the compartment. 
     
     
         15 . The method of  claim 14 , wherein the drive includes a piston and an actuator located within the reservoir, the actuator attached at one end to the piston and at the other end to a wall of the reservoir, the actuator configured to move the piston to transfer the liquid into the channel when thermal conductivity is desired and the gas into the channel when thermal conductivity is not desired. 
     
     
         16 . The method of  claim 15 , wherein the actuator includes a paraffin pellet in thermal communication with the compartment, the paraffin pellet configured to expand upon increase in temperature and contract upon decrease in temperature, the paraffin pellet configured so that the piston causes the liquid to be transferred into the channel when the paraffin pellet expands and causes the gas to be transferred into the channel when the paraffin pellet contracts. 
     
     
         17 . The method of  claim 15 , wherein the actuator includes a bimetal or snap disk actuator in thermal communication with the compartment so as to move the displacer piston in response to the temperature of the compartment. 
     
     
         18 . The method of  claim 15 , wherein the actuator includes a fluid expansion actuator that communicates with the compartment through a temperature sense bulb so as to move the displacer piston in response to the temperature of the compartment. 
     
     
         19 . The method of  claim 14 , wherein the drive includes a pump with variable speed that transfers the liquid into the channel when in operation and the gas is within the channel when the pump is not in operation. 
     
     
         20 . The method of  claim 13 , wherein a wall of the channel includes at least one fin that protrudes into the channel.