Articles and devices for thermal energy storage and methods thereof

Abstract

The present invention relates to articles and heat storage devices for storage of thermal energy. The articles include a metal base sheet and a metal cover sheet, wherein the metal base sheet and the metal cover sheet are sealingly joined to form one or more sealed spaces. The articles include a thermal energy storage material that is contained within the sealed spaces. The sealed spaces preferably are substantially free of water or includes liquid water at a concentration of about 1 percent by volume or less at a temperature of about 25° C., based on the total volume of the sealed spaces. The articles include one or more of the following features: a) the pressure in a sealed space is about 700 Torr or less, when the temperature of the thermal energy storage material is about 25° C.; b) the metal cover sheet includes one or more stiffening features, wherein the stiffening features include indents into the sealed space, protrusions out of the sealed space, or both, that are sufficient in size and number to reduce the maximum von Mises stress in the cover sheet during thermal cycling; c) the metal cover sheet and / or the metal base sheet includes one or more volume expansion features; or d) the metal cover sheet has a thickness, tc, and the metal base sheet has a thickness, tb, wherein tc is greater than tb; so that the article is durable. For example, the article does not leak after thermal cycling between about 25° C. and about 240° C., for 1,000 cycles.

Description

CLAIM OF BENEFIT OF FILING DATE[0001]The present invention claims the benefit of the filing date of U.S. Provisional Patent Application No. 61 / 373,008, filed on Aug. 12, 2010, the contents of which are hereby incorporated by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates to thermal energy storage using a thermal energy storage material and to the packaging of the thermal energy storage material to allow for both efficient heat storage and efficient heat transfer.BACKGROUND OF THE INVENTION[0003]Industry in general has been actively seeking a novel approach to capture and store waste heat efficiently such that it can be utilized at a more opportune time. Further, the desire to achieve .energy storage in a compact space demands the development of novel materials that are capable of storing high energy content per unit weight and unit volume. Areas of potential application of breakthrough technology include transportation, solar energy, industrial...

AI Technical Summary

Benefits of technology

The invention is an article that contains a high concentration of thermal energy storage material, which can be heated to a high temperature and has a high surface area for quick heat transfer. The article has multiple flow paths for uniform heat transfer, is strong and durable, and has a high heat storage density. The article is also designed to prevent leakage of the thermal energy storage material and to reduce the pumping requirements for the heat transfer fluid. The invention also includes a device containing multiple articles and a process for preparing the article.

Problems solved by technology

Regarding the transportation industry, it is well known that internal combustion engines operate inefficiently.

Sources of this inefficiency include heat lost via exhaust, cooling, radiant heat and mechanical losses from the system.

It is estimated that more than 30% of the fuel energy supplied to an internal combustion engine (internal combustion engine) is lost to the environment via engine exhaust.

It is well known that during a “cold start” internal combustion engines operate at substantially lower efficiency, generate more emissions, or both, because combustion is occurring at a non-optimum temperature and the internal combustion engine needs to perform extra work against friction due to high viscosity of cold lubricant.

This problem is even more important for hybrid electric vehicles in which the internal combustion engine operates intermittently thereby prolonging the cold start conditions, and / or causing a plurality of occurrences of cold start conditions during a single period of operating the vehicle.

However, in order to provide a long term (e.g., greater than about 6 hour) heat storage capability, they generally occupy a large volume, require pumping of a large volume of heat transfer fluid, require a relatively large pump to overcome the hydraulic resistance, and the like.

The issue of packaging of the thermal energy storage materials for applications requiring systems that are light weight, such as in transportation, requires both strong packaging and packaging that is light weight.

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