r '- 



One would generate hydrogen along a low teiaperature-pressure dissocia- 

 tion plateau. The heat for this generation could be taken from the 

 outside atmosphere. The hydrogen thus released would ba compressed to 

 a pressure that would cause the second hydride unit to absorb the 

 hydrogen at a tetsperature-presaure plateau above the room temperature. 

 This second container would release heat at this elevated temperature 

 which could be transferred to the room air, thereby wanting the roost- 

 The only power necessary for the system would be used by the compressor 

 to pressurize the hydrogen- 

 Appendix A shows the analysis of this system. An expression for 

 the coefficient of performance is the final result of the analysis. The 

 coefficient of performance can be visualized as the ratio of the amotst 

 of heat delivered into the house per unit of energy used to deliver it. 

 The best heat pumps have the highest coefficients of performance. 



Once the expression for the coefficient of performance was found, 

 typical values were assumed for the iseatropic compressor efficiency and 

 the temperatures and pressures of the components of the system. A 

 typical isentropic compressor efficiency is 90Z. The atmospheric tem- 

 perature was assumed to be AO F. To proaote a heat flow to the low 

 temperature hydride, the hydride was assumed to be absorbing heat at 

 such a rate that it maintained a temperature of 30°F. The compressor 

 output pressures were assumed at several values to see how this affected 

 the coefficient of performance. The table shown at the end of Appendix 

 A is the result of these calculations. It can be seen th3t the highest 

 coefficients of performance are obtained when the compressor output 

 pressures are low. This makes, sense because less energy will be spent 

 to compress the hydrogen. A typical present technology heat pump can be 

 expected to have a coefficient of performance of 2 to 3 [65, 67]. Ttras, 

 if pressures can be kept low it is conceivable that a superior heat punp 

 could be built using metal hydrides. 



PROBLEMS AND SOLUTIONS 



Several problems occur with each of the above systems. The problems 

 center around how to heat the hydride during generation of the hydrogea 

 and how to cool the hydride during absorption of the hydrogen. In 

 heating the hydride, the most desirable system will use a minimum of the 

 fuel. The most preferable situation uses only exhaust products to heat 

 the hydride. In c-?ling the hydride the most desirable system will use 

 the heat generateu to perform some other task such as heating water, 

 heating buildings, providing processed steam, or supplying the heat' 

 needed for an absorption cooling system. Thus, the hydride system 

 appears capable of squeezing more useful energy out of each pound of 

 fuel than would normally be the case. 



34 



