This project will develop an automobile air conditioner that includes a heat pump driven by waste heat in the engine exhaust. The pump includes no moving parts. The working medium is hydrogen, which shuttles between two heat exchangers whose surfaces are coated with metal hydride. A technique for coating a metal surface with a metal hydride using silicone rubber (which has a high permeability for hydrogen) as the binder has already been developed. This coated surface was cycled through 2,900 cycles of hydriding and dehydriding. There was a gradual loss of capacity to absorb hydrogen, caused probably by traces of water in the hydrogen. Water is a decomposition product of silicone rubber. If the hydrogen could be kept absolutely dry, decomposition should be arrested and capacity should remain constant. The objective is to prove this. In Phase I a prototype heat pump will be built and cycled at least 3,000 times. A molecular sieve will be used to capture the water and keep the hydrogen dry. Existing automobile air conditioners increase engine load by 5 to 10 HP and use chlorofluorocarbons (CFCs) as the working medium. The proposed air conditioner would save gasoline and reduce CFC emissions, which destroy ozone in the upper atmosphere.Anticipated Results/Potential Commercial Applications as described by the awardee:There is an incentive to air condition commercial buildings with a heat pump driven by waste heat. An efficient heat pump has not been developed. However, if the planned heat pump is efficient, it would have use in buildings, refrigerated trucks, ships, and army tanks. A heat exchanger coated with hydride can store hydrogen for use in a space craft, for example.
