SBIR-STTR Award

Pollution of the environment from hydrocarbons used in conventional refrigeration systems is a serious threat. To reduce this problem, refrigeration systems are planned based on the use of hydrogen absorbed and desorbed between two different metal hydrides. Because these materials store extremely large volumes of hydrogen, they have great potential for cooling and refrigeration, which occurs when hydrogen is desorbed from one of the hydrides in the system. However, no current hydrogen system designs have a coefficient of performance (COP) large enough to compete with conventional chlorofluorocarbon (CFC) systems. During some recently completed research work, an approach that allows a hydride-driven refrigeration system to exceed the COP of conventional CFC systems was discovered. Based on calculations, this innovative system, with a choice of certain metal hydride pairs, approaches the efficiency of a Carnot cycle, and the COP can be as high as 1.0. The purpose of the Phase I research is to test a laboratory working model of this innovative hydride-driven refrigerator and to demonstrate. the feasibility of the approach. Experimentally determined COPs near 1.0 will corroborate the calculations and prove that metal hydride systems can be made to be very competitive with conventional refrigeration systems. This approach is a general one, so that systems designed for residential and automobile air conditioners as well as commercial and residential refrigerators, can be made pollution free.Anticipated Results/Potential Commercial Applications as described by the awardee:The successful conclusion of this Phase I research is expected to lead to commercial application of CFC free refrigeration and cooling systems for residential and industrial uses.

The use of chloro-fluoro-hydrocarbons is a major contributor to the environmental pollution problem which this country is trying to minimize through the promotion of alternative means of running refrigeration and air conditioning systems. One of the most promising of these alternatives is the use of hydrogen as the refrigerant in the form of metal hydrides. While this idea has been pursued for a number of years, the inability of hydride driven heat pump refrigerators to perform at levels competitive with conventional freon refrigeration systems has prevented their general acceptance. Consequently, it has been the principal objective of this project to increase the coefficient of performance (COP) of metal hydride systems used as heat pumps to run refrigerators and air conditioners for residential and commercial use. In Phase I an innovative means of achieving this goal was developed. This major advance in hydride driven refrigerator technology was achieved by an innovative use of two metal hydrides in which the energy of absorption of hydrogen into the refrigerant from the decomposing regenerator hydride was used to supply a very large fraction of the energy required for the regeneration portion of the cycle. This approach for increasing the COP of metal hydride heat pumps cannot be used with the present configuration of hydride driven refrigerators. Phase I demonstrated that the new hydride driven refrigeration cycle can perform at levels which exceed conventional vapor compression refrigerators. Based on this research, Phase II will be devoted to producing a prototype refrigerator using the innovative metal hydride approach and comparing its performance to a conventional freon vapor driven refrigerator.Anticipated Results /Potential Commercial Applications as described by the awardee:Residential and commercial refrigerator systems, as well as air conditioners for automobiles and homes, based on hydrogen, could attain performance levels which are competitive with conventional freon vapor compression units.