Two-phase cooling system

Abstract

A two-phase cooling system can include a primary cooling loop and a heat rejection loop. The primary cooling loop can include a reservoir, a first pump fluidly connected to the primary cooling loop downstream of the reservoir, and a heat sink module fluidly connected to the primary cooling loop downstream of the first pump and upstream of the reservoir. The first pump can draw dielectric coolant from the reservoir and provide a primary flow of pressurized dielectric coolant through the primary cooling loop, with a first portion flowing through the heat sink module and a second portion flowing through a bypass. The heat rejection loop can be fluidly connected to the same reservoir and can include a second pump and a heat exchanger. The second pump can draw dielectric coolant from the reservoir and provide a secondary flow of pressurized coolant through the heat exchanger and back to the reservoir.

What is claimed is: 
     
         1 . A two-phase cooling system comprising:
 a primary cooling loop comprising: a reservoir; a first pump fluidly connected to the primary cooling loop downstream of the reservoir; and a heat sink module fluidly connected to the primary cooling loop downstream of the first pump and upstream of the reservoir;   a bypass comprising a first end; a second end; and a valve installed between the first end and the second end of the bypass, the first end of the bypass fluidly connected to the primary cooling loop downstream of the first pump and upstream of the heat sink module, the second end of the bypass fluidly connected to the primary cooling loop downstream of the heat sink module and upstream of the reservoir, wherein the first pump is configured to draw dielectric coolant from the reservoir and provide a primary flow of pressurized dielectric coolant through the primary cooling loop, wherein a first portion of the primary flow is configured to pass through the heat sink module and a second portion of the primary flow is configured to pass through the bypass, and wherein the first and second portions of the primary flow are configured to mix before returning to the reservoir; and   a heat rejection loop comprising a first end fluidly connected to the reservoir; a second pump fluidly connected to the heat rejection loop downstream of the first end; a heat exchanger fluidly connected to the heat rejection loop downstream of the second pump; and a second end fluidly connected to the reservoir, wherein the second pump is configured to draw dielectric coolant from the reservoir and provide a secondary flow of pressurized coolant through the heat exchanger and back to the reservoir.   
     
     
         2 . The two-phase cooling system of  claim 1 , wherein the valve is a differential pressure valve comprising a valve inlet and a valve outlet, the valve adapted to control a flow of pressurized coolant through the bypass by establishing a pressure differential of about 2-10, 5-12, 10-15, or 10-25 psi between the valve inlet and the valve outlet when pressurized coolant is delivered to the valve inlet. 
     
     
         3 . The two-phase cooling system of  claim 1 , wherein the first pump is configured to provide a primary flow at a pressure of about 5-15, 10-20, 15-25, 20-30, 25-35, 30-40, 35-45, or 40-50 psi, and wherein the first pump is configured to provide a flow rate of about 0.25-1.0, 0.5-1.5, 1.0-2.0, 1.5-2.5, 2.0-3.0, 2.5-3.5, 3.0-4.0, 3.5-4.5, 4.0-5.0, 4.5-5.5, or 5.0-6.0 liters per minute through the heat sink module as the first portion of the primary flow. 
     
     
         4 . The two-phase cooling system of  claim 1 , wherein the heat sink module comprises: an inlet chamber; an outlet chamber; and a plurality of orifices fluidly connecting the inlet chamber to the outlet chamber, the plurality of orifices comprising an array of at least 10, 20, 30, 40, 50, or 60 orifices, the plurality of orifices having an average diameter of about 0.001-0.01, 0.005-0.025, 0.015-0.035, 0.025-0.050, 0.035-0.05, 0.04-0.06, 0.05-0.08, 0.07-0.1, 0.08-0.12, 0.1-0.15, 0.14-0.18, 0.16-0.2, or 0.04 in. 
     
     
         5 . The two-phase cooling system of  claim 1 , further comprising a thermally conductive base member configured to mount on, or be placed in thermal communication with, a heat source, wherein the heat sink module comprises a bottom surface configured to seal against a surface of the thermally conductive base member, the heat sink module comprising: an inlet chamber formed within the heat sink module; an outlet chamber formed in the heat sink module and bounded by the surface of the thermally conductive base member when the heat sink module is mounted on the thermally conductive base member; and a first plurality of orifices extending from the inlet chamber to the outlet chamber, the first plurality of orifices configured to deliver a plurality of jet streams of coolant into the outlet chamber and against the surface of the thermally conductive base member when pressurized coolant is provided to the inlet chamber by the first pump. 
     
     
         6 . The two-phase cooling system of  claim 5 , wherein the plurality of orifices have an average jet height of about 0.01-0.75, 0.05-0.5, 0.05-0.25, 0.020-0.25, 0.03-0.125, or 0.04-0.08 in., wherein jet height of each orifice in the plurality of orifices is measured as a shortest distance from an exit of the orifice to the surface of the thermally conductive base member. 
     
     
         7 . The two-phase cooling system of  claim 1 , wherein the inlet chamber has a volume of about 0.01-0.02, 0.01-0.05, 0.04-0.08, 0.07-0.15, 0.1-0.2, 0.15-0.25, 0.2-0.4, or 0.3-0.5 cubic inches, and wherein the outlet chamber has a volume of about 0.02-0.05, 0.04-0.08, 0.07-0.15, 0.1-0.2, 0.15-0.25, 0.2-0.4, 0.3-0.5, or 0.4-0.75 cubic inches. 
     
     
         8 . The two-phase cooling system of  claim 1 , wherein the cooling system is adapted for use in a computer, and the cooling system further comprises a fan mounted to the heat exchanger. 
     
     
         9 . The two-phase cooling system of  claim 1 , further comprising an electronic control unit; a first variable speed drive connected to the first pump; a second variable speed drive connected to the second pump; and a sensor capable of detecting a flow characteristic of the coolant and transmitting a signal corresponding to the flow characteristic of the coolant to the electronic control unit, wherein the electronic control unit is configured to adjust a speed of the first variable speed drive and a speed of the second variable speed drive based on the signal received from the sensor. 
     
     
         10 . The two-phase cooling system of  claim 9 , wherein the sensor is a vapor quality sensor attached to the primary cooling loop downstream of the heat sink module and upstream of the reservoir. 
     
     
         11 . The two-phase cooling system of  claim 1 , wherein about 35-65, 45-55, or 50% of the primary flow from the first pump is configured to pass through the bypass. 
     
     
         12 . A two-phase cooling system comprising:
 a primary cooling loop comprising: a first end fluidly connected to a reservoir; a first pump fluidly connected to the primary cooling loop downstream of the first end; a manifold assembly fluidly connected to the primary cooling loop downstream of the first pump; and a second end fluidly connected to the reservoir, wherein the first pump is configured to provide a primary flow of pressurized coolant through the primary cooling loop; and   a heat rejection loop comprising: a first end fluidly connected to the reservoir; a second pump fluidly connected to the heat rejection loop downstream of the first end of the heat rejection loop; a heat exchanger fluidly connected to the heat rejection loop downstream of the second pump; and a second end fluidly connected to the reservoir, wherein the second pump is configured to draw dielectric coolant from the reservoir and provide a secondary flow of pressurized coolant through the heat exchanger and back to the reservoir.   
     
     
         13 . The two-phase cooling system of  claim 12 , wherein the first end of the primary cooling loop is fluidly connected to the reservoir at a first location, and the second end of the primary cooling loop is fluidly connected to the reservoir at a second location, the first location being at least one inch lower on the reservoir than the second location, measured vertically between midpoints of the first location and the second location. 
     
     
         14 . The two-phase cooling system of  claim 12 , wherein the first end of the heat rejection loop is fluidly connected to the reservoir at a third location, and the second end of the heat rejection loop is fluidly connected to the reservoir at a fourth location, the third location being at least one inch lower on the reservoir than the fourth location, measured vertically between midpoints of the third location and the fourth location. 
     
     
         15 . The two-phase cooling system of  claim 12 , wherein the manifold assembly comprises:
 an inlet chamber comprising a first plurality of fittings installed in a first plurality of openings passing through a bounding surface of the inlet chamber;   an outlet chamber comprising a second plurality of fittings installed in a second plurality of openings passing through a bounding surface of the outlet chamber; and   a bypass fluidly connecting the inlet chamber to the outlet chamber, the bypass comprising a differential pressure bypass valve configured to control a flow of pressurized coolant from the inlet chamber to the outlet chamber through the bypass to maintain a pressure differential between the inlet chamber and the outlet chamber.   
     
     
         16 . The two-phase cooling system of  claim 15 , further comprising a flexible cooling line assembly, the flexible cooling line assembly comprising: a first end; a second end; and a heat sink module fluidly connected between the first end and the second end of the flexible cooling line assembly, wherein the first end of the flexible cooling line assembly is fluidly connected to one of the first plurality of fittings installed in the inlet chamber of the manifold assembly, and wherein the second end of the flexible cooling line assembly is fluidly connected to one of the second plurality of fittings installed in the outlet chamber of the manifold assembly. 
     
     
         17 . The two-phase cooling system of  claim 15 , wherein the differential pressure bypass valve comprises a valve inlet fluidly connected to the inlet chamber and a valve outlet fluidly connected to the outlet chamber, the differential pressure bypass valve being configured to control a flow of pressurized coolant through the bypass by establishing the pressure differential of about 2-10, 5-12, 10-15, or 10-25 psi between the valve inlet and the valve outlet. 
     
     
         18 . The two-phase cooling system of  claim 15 , wherein the first pump is configured to provide a primary flow of pressurized coolant of about 4-10, 8-16, 20-32, 28-40, 40-56, or 54-64 liters per minute through the primary cooling loop at a pressure of about 5-20, 15-30, 25-45, 40-60, or 50-75 psi, wherein about 35-65, 45-55, or 50% of the flow from the first pump is configured to flow through the bypass. 
     
     
         19 . The two-phase cooling system of  claim 12 , further comprising: an electronic control unit; a variable speed drive connected to the first pump; and a sensor capable of detecting a flow characteristic of the primary flow of pressurized coolant and transmitting a signal corresponding to the flow characteristic to the electronic control unit, wherein the electronic control unit is configured to adjust a speed of the variable speed drive based on the signal received from the sensor. 
     
     
         20 . The two-phase cooling system of  claim 12 , further comprising: an electronic control unit; a variable speed drive connected to the second pump; and a sensor capable of detecting a flow characteristic of the secondary flow of pressurized coolant and transmitting a signal corresponding to the flow characteristic to the electronic control unit, wherein the electronic control unit is configured to adjust a speed of the variable speed drive based on the signal received from the sensor. 
     
     
         21 . The two-phase cooling system of  claim 19 , wherein the sensor is a vapor quality sensor, a temperature sensor, or a pressure sensor. 
     
     
         22 . The two-phase cooling system of  claim 12 , wherein the two-phase cooling system is adapted for use in a vehicle, and wherein the heat exchanger is an internal combustion engine radiator or is in thermal communication with an internal combustion engine radiator. 
     
     
         23 . The two-phase cooling system of  claim 12 , wherein the two-phase cooling system is adapted to cool a rack of servers, and wherein the heat exchanger is a liquid-to-liquid heat exchanger configured to fluidly connect to a supply of chilled water. 
     
     
         24 . A two-phase cooling system comprising:
 a primary cooling loop comprising: a reservoir; a first pump fluidly connected to the primary cooling loop downstream of the reservoir; and a first heat sink module fluidly connected to the primary cooling loop downstream of the first pump and upstream of the reservoir, wherein the first pump is configured to draw dielectric coolant from the reservoir and provide a primary flow of pressurized dielectric coolant through the first heat sink module and back to the reservoir, wherein the heat sink module comprises a plurality of orifices configured to provide a plurality of impinging jet streams of dielectric coolant against a surface to be cooled when the primary flow of pressurized coolant is delivered to an inlet of the heat sink module; and   a heat rejection loop comprising a first end fluidly connected to the reservoir; a second pump fluidly connected to the heat rejection loop downstream of the first end; a heat exchanger fluidly connected to the heat rejection loop downstream of the second pump; and a second end fluidly connected to the reservoir, wherein the second pump is configured to draw dielectric coolant from the reservoir and provide a secondary flow of pressurized coolant through the heat exchanger and back to the reservoir.   
     
     
         25 . The two-phase cooling system of  claim 24 , wherein the first pump is configured to provide a flow rate of 0.25-1.0, 0.5-1.5, 1.0-2.0, 1.5-2.5, 2.0-3.0, 2.5-3.5, 3.0-4.0, 3.5-4.5, 4.0-5.0, 4.5-5.5, or 5.0-6.0 liters per minute of dielectric coolant through the primary cooling loop, and wherein the second pump is configured to provide a flow rate of 0.25-1.0, 0.5-1.5, 1.0-2.0, 1.5-2.5, 2.0-3.0, 2.5-3.5, 3.0-4.0, 3.5-4.5, 4.0-5.0, 4.5-5.5, or 5.0-6.0 liters per minute of dielectric coolant through the heat rejection loop. 
     
     
         26 . The two-phase cooling system of  claim 25 , wherein the first pump is configured to provide a primary flow of pressurized coolant through the primary cooling loop at a pressure of about 5-15, 10-20, 15-25, 20-30, 25-35, 30-40, 35-45, or 40-50 psi while consuming 12 volts or less. 
     
     
         27 . The two-phase cooling system of  claim 24 , wherein the plurality of orifices have an average diameter of about 0.001-0.01, 0.005-0.025, 0.015-0.035, 0.025-0.050, 0.035-0.05, 0.04-0.06, 0.05-0.08, 0.07-0.1, 0.08-0.12, 0.1-0.15, 0.14-0.18, 0.16-0.2, or 0.04 in. 
     
     
         28 . The two-phase cooling system of  claim 24 , wherein the dielectric coolant is a hydrofluoroether or hydrofluorocarbon fluid. 
     
     
         29 . The two-phase cooling system of  claim 24 , wherein the cooling system is adapted for use in a computer, the cooling system further comprising a fan mounted to the heat exchanger and a memory cooler fluidly connected to the primary cooling loop downstream of the first pump and upstream of the reservoir.