As electronic components continue to advance and are made more powerful, they tend to produce more and more undesirable heat which is preferably removed. This has created a growing need for higher capacity cooling systems to remove heat from all or a portion of the electronic components.
As the trend is to make electronic components more powerful, there is also an increasing push to reduce the size of the electronic components, and the packaging of the electronic components. The smaller components and packaging makes the removal of the unwanted heat more difficult.
In some applications, direct impingement thin-film evaporative spray cooling is preferred in order to provide sufficient cooling, whereas in other applications spray cooling is desired to reduce the overall package or housing size even though the required cooling capability is not as high. This creates a situation in which transverse narrow gap evaporative spray cooling is advantageous if it can be done to an acceptable efficiency level.
Narrow gap evaporative spray cooling will preferably provide or spray the coolant from a transverse side of the surface to be cooled (or the surface from which heat is to be transferred). Proper cooling is preferably achieved if a thin liquid film is maintained over the device or electronic component to be cooled, thereby facilitating evaporation of the coolant as heat is transferred from the electronic component. If there is too little flow or coverage of coolant, the liquid layer covering the electronic component will dry out and cause the component to overheat because vapor forced convection will not typically provide sufficient heat transfer. If the flow of coolant to the component is too great, the device will become flooded and may produce hot spots, insufficient cooling and/or failure, because the vapor created from the evaporation may become trapped between the excessive fluid and the impingement surface of the electronic component. This will normally reduce the cooling efficiency. Vapor generated at the surface of the component which receives too much coolant cannot escape effectively and could result in a boiling heat transfer failure mode generally referred to as burnout.
Even when the volume flux of coolant is properly matched to the heat flux of the device, the excess fluid sprayed within a cavity must generally be managed by the method described in U.S. Pat. No. 5,220,804 to prevent the overflow from adjacent components from interfering and causing flooding type failure conditions.
It is therefore an objective of some embodiments of this invention to provide a narrow gap, thin-film, evaporative spray cooling system for cooling one or more electronic components in the narrow gap.
It is also an objective of some embodiments of this invention to provide a narrow gap evaporative spray cooling system which improves the cooling characteristics of the system, especially at the entry end of the cooling channel or conduit, and/or reduces the pressure gradient above the surface from which heat is to be transferred.
It is also an objective of some embodiments of this invention to provide a housing system which provides improved re-circulation of the vapor for re-introduction of the vapor into the cooling conduit.
It is an objective of some embodiments of this invention to provide a re-circulation system which reduces pooling of the liquid portion of the coolant at or near the exit end of the cooling conduit.