Flowrate controller for hybrid capillary/mechanical two-phase thermal loops

Claim 2

A closed-loop heat transfer system adapted to transfer heat from a heat source to a heat sink by means of a working fluid having a liquid phase and a vapor phase, said heat transfer system comprising: at least one evaporator having a plurality of capillaries adapted to accept heat from said heat source and to receive a flow of said liquid phase working fluid, with heat from said heat source causing at least a portion of said working fluid flowing through said capillaries to convert to said vapor phase; a condenser adapted to receive said working fluid from said evaporator, and to reject heat from said working fluid to said heat sink and thereby convert said vapor phase working fluid to its liquid phase; a sensor having: (a) a conductive tube with an inside diameter substantially greater than the inside diameters of said evaporator capillaries, connected in parallel with said evaporator; (b) a conductive wire extending within said tube insulated from electrical contact with said tube; and (c) capacitance measuring means adapted to measure the electrical capacitance between said tube and said wire and thereby indicate the amount of liquid phase working fluid within said tube; and a pump adapted to receive and pump liquid phase working fluid from said condenser to said evaporator, the output of said pump being regulated as a function of the capacitance measured by said capacitance measuring means to maintain a substantially constant amount of liquid phase working fluid within said sensor.

Claim 3

The heat transfer system of claim 1, wherein said sensor tube comprises a helically wound coiled tube.

Claim 4

The heat transfer system of claim 1, wherein said sensor tube comprises a spirally wound coiled tube.

Claim 5

The heat transfer system of claim 1, wherein said sensor tube comprises a serpentine tube.

Claim 6

The heat transfer system of claim 1, wherein said pump is a variable speed pump whose output is regulated as a function of the capacitance measured by said capacitance measuring means.

Claim 7

The heat transfer system of claim 1, wherein said pump is turned on whenever the amount of liquid phase working fluid measured in said sensor tube by said capacitance measuring means is below a predetermined lower limit, and said pump is turned off whenever the amount of liquid phase working fluid measured in said sensor tube is above a predetermined upper limit.

Claim 8

The heat transfer system of claim 1, wherein said wire is surrounded by a layer of electrical insulation.

Claim 9

The heat transfer system of claim 1, further comprising a bypass valve in parallel connection with said pump, adapted to permit said heat transfer system to function as a two-phase capillary pumped loop during periods when operation of said pump is not required for said evaporator to meet the thermal load of said evaporator.

Claim 10

The heat transfer system of claim 1, further comprising a reservoir adapted to receive and store a quantity of liquid phase working fluid returned from said condenser.

Claim 11

The heat transfer system of claim 9, further comprising a heater adapted to maintain a predetermined minimum saturation temperature of said liquid phase working fluid stored by said reservoir.

Claim 12

The heat transfer system of claim 1, further comprising an accumulator adapted to adjustably control the pressure of the liquid phase working fluid entering said pump.

Claim 13

The heat transfer system of claim 1, further comprising a gas trap adapted to prevent vapor phase working fluid and non-condensible gases from entering said evaporator.

Claim 14

The heat transfer system of claim 1, further comprising: a temperature sensor adapted to monitor the temperature of said evaporator; and repriming control means adapted to cause said pump to substantially increase the flowrate of working fluid to said evaporator if the temperature of said evaporator exceeds a predetermined limit.

Claim 15

The heat transfer system of claim 13, further comprising a shut-off valve closed by said repriming control means during said periods of increased pump flowrate to prevent the flow of working fluid through said sensor during said periods of increased pump flowrate.

Claim 16

A closed-loop heat transfer system adapted to transfer heat from a number of heat sources to a heat sink by means of a working fluid having a liquid phase and a vapor phase, said heat transfer system comprising: a plurality of evaporators connected in parallel, each evaporator having a plurality of capillaries adapted to accept heat from a heat source and to receive a flow of said liquid phase working fluid, with heat from at least one of said heat sources causing at least a portion of said working fluid flowing through said capillaries to convert to said vapor phase; a condenser adapted to receive said working fluid from said evaporators, and to reject heat from said working fluid to said heat sink and thereby convert said vapor phase working fluid to its liquid phase; a pump adapted to receive and pump liquid phase working fluid from said condenser to said evaporators; a sensor having: (a) a conductive tube with an inside diameter substantially greater than the inside diameters of said evaporator capillaries, connected in parallel with said evaporators; (b) a conductive wire extending within said tube insulated from electrical contact with said tube; and (c) capacitance measuring means adapted to measure the electrical capacitance between said tube and said wire and thereby indicate the amount of liquid phase working fluid within said sensor tube; and control means adapted to regulate the output of said pump as a function of the electrical capacitance measured by said capacitance measuring means, to thereby maintain a substantially constant amount of liquid phase working fluid within said sensor.

Claim 17

A closed-loop heat transfer system adapted to transfer heat from a number of heat sources to a heat sink by means of a working fluid having a liquid phase and a vapor phase, said heat transfer system comprising: a plurality of evaporators connected in parallel, each evaporator having a plurality of capillaries adapted to accept heat from a heat source and to receive a flow of said liquid phase working fluid, with heat from at least one of said heat sources causing at least a portion of said working fluid flowing through said capillaries to convert to said vapor phase; a condenser adapted to receive said working fluid from said evaporators, and to reject heat from said working fluid to said heat sink and thereby convert said vapor phase working fluid to its liquid phase; a pump adapted to receive and pump liquid phase working fluid from said condenser to said evaporators; a sensor having: (a) a conductive tube with an inside diameter substantially greater than the inside diameters of said evaporator capillaries, connected in parallel with said evaporators; (b) a conductive wire extending within said tube insulated from electrical contact with said tube; and (c) capacitance measuring means adapted to measure the electrical capacitance between said tube and said wire and thereby indicate the amount of liquid phase working fluid within said sensor tube; and control means adapted to regulate the output of said pump as a function of the electrical capacitance measured by said capacitance measuring means, to thereby maintain a substantially constant amount of liquid phase working fluid within said sensor.

Claim 18

The heat transfer system of claim 15, wherein said sensor tube comprises a helically coiled tube.

Claim 19

The heat transfer system of claim 15, wherein said sensor tube comprises a spirally wound coiled tube.

Claim 20

The heat transfer system of claim 15, wherein said sensor tube comprises a serpentine tube.

Claim 21

The heat transfer system of claim 15, wherein said wire is surrounded by a layer of electrical insulation.

Claim 22

The heat transfer system of claim 15, further comprising a bypass valve in parallel connection with said pump and a sensor shut-off valve in series connection with said sensor, adapted to permit said heat transfer system to function as a two-phase capillary pumped loop during periods when operation of said pump is not required for said evaporators to meet thermal loads.

Claim 23

The heat transfer system of claim 15, further comprising a reservoir adapted to receive and store a quantity of liquid phase working fluid returned from said condenser.

Claim 24

The heat transfer system of claim 21, further comprising a heater adapted to maintain a predetermined minimum saturation temperature of said liquid phase working fluid stored by said reservoir.

Claim 25

The heat transfer system of claim 15, further comprising an accumulator controlled by said control means, adapted to adjustably control the pressure of the liquid phase working fluid entering said pump.

Claim 26

The heat transfer system of claim 15, further comprising a gas trap adapted to prevent vapor phase working fluid and non-condensible gases from entering said evaporators.

Claim 27

The heat transfer system of claim 15, further comprising: a temperature sensor adapted to monitor the temperature of said evaporators; and repriming control means adapted to cause said pump to substantially increase the flowrate of working fluid to said evaporators if the temperature of said evaporators exceeds a predetermined limit.

Claim 28

The heat transfer system of claim 25, further comprising a shut-off valve closed by said repriming control means during said periods of increased pump flowrate to prevent the flow of working fluid through said sensor during said periods.

Claim 29

A closed-loop heat transfer system adapted to transfer heat from a number of heat sources to a heat sink by means of a working fluid having a liquid phase and a vapor phase, said heat transfer system comprising: a plurality of evaporators, each evaporator having an inlet and an outlet connected in parallel with the remaining evaporators, and containing a capillary structure adapted to act as a wick for liquid phase working fluid entering through said evaporator inlet, with heat from at least one of said heat sources causing at least a portion of said liquid phase working fluid to convert to said vapor phase and exit through said evaporator outlet; a temperature sensor means adapted to monitor the temperature of said evaporators; a condenser adapted to receive said working fluid from said evaporator outlets, and to reject heat from said working fluid to said heat sink and thereby return a substantial portion of said vapor phase working fluid to its liquid phase; a reservoir adapted to receive and store a quantity of liquid phase working fluid returned from said condenser; a pump adapted to receive and pump liquid phase working fluid from said condenser and said reservoir to said evaporator inlets; a liquid sensor having: (a) a coiled, conductive tube with an inside diameter substantially greater than the inside diameters of said evaporator capillaries, connected in parallel with said evaporators; (b) a conductive wire extending within said tube insulated from electrical contact with said tube, such that working fluid acts as a dielectric material between said tube and said wire; and (c) capacitance measuring means adapted to measure the electrical capacitance between said tube and said wire and thereby indicate the amount of liquid phase working fluid within said tube; and control means having: (a) a normal mode of operation in which said control means regulates the output of said pump as a function of the electrical capacitance measured by said capacitance measuring means, to thereby maintain a substantially constant amount of liquid phase working fluid within said liquid sensor tube; and (b) a repriming mode of operation triggered when the temperature for any evaporator measured by said temperature sensor exceeds a predetermined limit, in which said control means causes said pump to substantially increase the flowrate of working fluid to flood said evaporators.

Claim 30

A closed-loop heat transfer system adapted to transfer heat from a number of heat sources to a heat sink by means of a working fluid having a liquid phase and a vapor phase, said heat transfer system comprising: a plurality of evaporators, each evaporator having an inlet and an outlet connected in parallel with the remaining evaporators, and containing a capillary structure adapted to act as a wick for liquid phase working fluid entering through said evaporator inlet, with heat from at least one of said heat sources causing at least a portion of said liquid phase working fluid to convert to said vapor phase and exit through said evaporator outlet; a temperature sensor means adapted to monitor the temperature of said evaporators; a condenser adapted to receive said working fluid from said evaporator outlets, and to reject heat from said working fluid to said heat sink and thereby return a substantial portion of said vapor phase working fluid to its liquid phase; a reservoir adapted to receive and store a quantity of liquid phase working fluid returned from said condenser; a pump adapted to receive and pump liquid phase working fluid from said condenser and said reservoir to said evaporator inlets; a liquid sensor having: (a) a coiled, conductive tube with an inside diameter substantially greater than the inside diameters of said evaporator capillaries, connected in parallel with said evaporators; (b) a conductive wire extending within said tube insulated from electrical contact with said tube, such that working fluid acts as a dielectric material between said tube and said wire; and (c) capacitance measuring means adapted to measure the electrical capacitance between said tube and said wire and thereby indicate the amount of liquid phase working fluid within said tube; and control means having: (a) a normal mode of operation in which said control means regulates the output of said pump as a function of the electrical capacitance measured by said capacitance measuring means, to thereby maintain a substantially constant amount of liquid phase working fluid within said liquid sensor tube; and (b) a repriming mode of operation triggered when the temperature for any evaporator measured by said temperature sensor exceeds a predetermined limit, in which said control means causes said pump to substantially increase the flowrate of working fluid to flood said evaporators.

Claim 31

The heat transfer system of claim 27, further comprising a shut-off valve closed by said control means during said repriming mode to prevent the flow of working fluid through said liquid sensor during said repriming mode.

Claim 32

The heat transfer system of claim 27, further comprising a bypass valve in parallel connection with said pump and a sensor shut-off valve in series connection with said sensor, adapted to permit said heat transfer system to function as a two-phase capillary pumped loop during periods when operation of said pump is not required for said evaporators to meet thermal loads.

Claim 33

The heat transfer system of claim 27, further comprising a heater adapted to maintain a predetermined minimum saturation temperature of said liquid phase working fluid stored by said reservoir.

Claim 34

The heat transfer system of claim 27, further comprising an accumulator controlled by said control means, adapted to adjustably control the pressure of the liquid phase working fluid entering said pump.

Claim 35

The heat transfer system of claim 27, further comprising a gas trap adapted to prevent vapor phase working fluid and non-condensible gases from entering said evaporators.