Two-phase-flow, panel-cooled, battery apparatus and method

Abstract

Two-phase, boiling heat transfer in confined channels close to a source of heat, such as an electrical component or device, carries the latent heat of vapors away to remote locations where “real estate” demands of air convection are tolerable operationally, economically, and technologically. Liquid-to-vapor, phase-change, heat transfer in a narrow channel (e.g., typically less than 0.200 inches total thickness, and often less than 0.150 in the channel itself) improves by several hundred percent the heat extraction from modest temperature (e.g., about 120 degree F.) devices, when compared to heat fluxes in pool boiling. Saturated working fluids provide nearly isothermal conditions in the working fluid. Minimal conduction paths provide minimal temperature gradients, and capillary action may maintain nearly constant temperature conditions about a surface of a heat source, while carrying heat of vaporization away to a condensation location.

Description

RELATED APPLICATIONS[0001]This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61 / 167,019, filed: Apr. 6, 2009 and entitled TWO-PHASE-FLOW, PANEL-COOLED, BATTERY APPARATUS AND METHOD, which is incorporated herein by reference. Also, this patent application incorporates herein by reference U.S. patent application Ser. No. 11 / 743,555, filed on May 2, 2007 and U.S. patent application Ser. No. 12 / 417,552, filed on Apr. 2, 2009.BACKGROUND[0002]1. The Field of the Invention[0003]This invention relates to heat transfer and, more particularly, to novel systems and methods for two-phase cooling of battery packs using comparatively modest temperature differentials.[0004]2. The Background Art[0005]A drawback and technical limitation of high-density populations of electronic components and chips is the difficulty of cooling. Electrical processes reject heat that must be carried away. With greater integration of electronic components, heat rejection cannot b...

AI Technical Summary

Benefits of technology

[0012]In alternative embodiments, the housing may be a sealed container having electrical components deployed on planar substrates, such as electronic components mounted on a printed circuit board, plates of a lithium-ion battery, or plates of some other battery system. The substrates may typically be arranged in banks or batteries of parallel, planar, walls with the working fluid free to pass completely around the components and substrates in intimate contact. For example, a dielectric coolant may eliminate the need for discrete panels to carry heat away from heat sources. Thus, the operational descriptions herein regarding enclosed, sealed panels, may be said, and is intended to apply, to banks of panels sealed in a single housing surrounding the entire bank or battery of heating panels.

[0013]Even concentric cylinders around cylindrical batteries can create the operation of bubble-scrubbing, enhancing free convection of liquids and vapors in a narrow channel.

[0022]In one embodiment, a loop setup may provide for a remote condenser. This may assist in reducing the frictional and entrainment losses in the apparatus Likewise, the difficulty of vapors at comparatively higher volumes passing through liquids at comparatively lower volumes has the added problem of entrainment, trapping, drying out, and the like in certain environments.

[0024]The temperature of the working fluid may be controlled by changing the flow of the external fluids through the heat exchanger external to the panel. Due to the buoyancy and resulting column pressure differential between the heat absorbing portion of the panel and the heat rejecting portion of the panel connected to the external heat exchanger, the flow of the working fluid may operate by substantially free convection, although restricted within a confined space. In certain embodiments, the apparatus may operate substantially passively. Likewise, the system may be pumped but need not be. Even with an external heat exchanger located remotely from the panels, free convection may control the two-phase transport processes.

[0027]If coatings are used on the heat sources, then it may be important to render them as thin as possible in order to minimize the length of the conductive path for heat. Thus, the thinner the conductive path, the less resistance to heat flow in the apparatus.

Problems solved by technology

Conduction may be limited to very short paths.

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