Thermal energy storage apparatus

Abstract

The present invention provides a thermal energy storage (TES) apparatus having a fast response to heat, which is also simple, lightweight, compact, and inexpensive to fabricate. In one preferred embodiment of the present invention, phase change material (PCM) is enclosed in a tubular container. A brush-like heat spreading element having radial bristles is installed in the tube within the PCM. The bristles are made of wires or fibers having good thermal conductivity and their ends are in a good thermal contact with the interior wall of the tube. Heat from external source is deposited into the tube exterior and conducted through the wall, transferred to the bristles, and conducted through the bristles in a generally radial direction substantially through out the PCM volume. The TES may be used in buildings to stabilize temperature and thus reduce the cost of building climate control such as heating and air conditioning.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from the U.S. provisional patent application U.S. Ser. No. 61 / 201,885, filed on Dec. 16, 2008, entitled “THERMAL ENERGY STORAGE APPARATUS.”GOVERNMENT RIGHTS IN THIS INVENTION[0002]This invention was made with U.S. government support under contract number FA8650-08-M-5026. The U.S. government may have certain rights in this invention.FIELD OF THE INVENTION[0003]This invention relates generally to apparatus and methods for conduction of heat and more specifically to to apparatus and methods for storage of thermal energy.BACKGROUND OF THE INVENTION[0004]The invention is for a thermal energy storage (TES) apparatus and method. TES is often used in devices and systems to temporarily store heat. For example, a TES apparatus may be used to average out a temperature in a heating system in a building or a vehicle with the objective of reducing the cost of energy expended in heating. In particular, TES can reduce th...

AI Technical Summary

Benefits of technology

[0009]The present invention provides a TES apparatus having a fast response to heat, which is also simple, lightweight, compact, and inexpensive to fabricate.

[0010]In one preferred embodiment of the present invention, TES is configured as a tubular container (tube) substantially filled with PCM. A heat spreading element (HSE) having radial bristles is installed in the tube within the PCM. The HSE may be formed as a brush, having bristles extending radially from a central core. Brushes having bristles made of appropriate material and extending radially from a central core have been known in prior art as “pipe brushes”, see FIG. 1. Pipe brushes are typically used for cleaning of pipes, types, bottles, and laboratory test tubes. In the HSE of the subject invention, the bristles are made of wires or fibers having good thermal conductivity. Ends of the bristles are arranged to be in a good thermal contact with the interior wall of the tubular container. Heat from an external medium, which may be liquid, gas, solid, or environment is deposited into the exterior surface of the tubular container, conducted through the container wall, transferred to the bristles, and conducted through the bristles in a generally radial direction, and substantially transferred into the PCM. Conversely, heat may be released by the PCM, deposited substantially into the HSE bristles, conducted through the bristles and into the interior wall of the tubular container, conducted through the the container wall, and transferred from the exterior surface of the tubular container into a liquid, gas, solid, or environment. In either case, conduction of heat in radial directly inside the TES tubular contained takes place substantially in the radial bristles, thereby greatly enhancing the speed at which heat can be transferred to and from the volume of the PCM.

[0011]Accordingly, it is an object of the present invention to provide a TES apparatus having the capability to rapidly absorb large amounts of heat, which is also simple, lightweight, compact, and inexpensive to fabricate.

[0012]It is another object of the invention to provide a TES apparatus having the capability to rapidly release large amounts of heat, which is also simple, lightweight, compact, and inexpensive to fabricate.

[0013]It is yet another object of the invention to provide a heat spreading element which is also simple, lightweight, compact, and inexpensive to fabricate.

Problems solved by technology

The absorption of the necessary quantity of energy by the solid PCM results in melting.

Many PCM capable of storing significant amount of heat are also very poor thermal conductors.

This makes it very challenging to transport heat into and out of the PCM, and limits the usefulness of such PCM in a TES.

However, heat spreading elements of prior art are heavy, bulky, expensive to construct, and expensive to install into the TES.

In summary, prior art does not teach a TES capable of fast response to applied heat that is also simple, lightweight, compact, and inexpensive to fabricate.

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