hydrogen released by the hydride to provide the extra heat needed by the 

 magnesiun-nldel hydride. An analysis for this is also planned but not 

 yet executed. This systea sight be necessary in situations where there 

 is no cos&mstion. 



Cooling Systems 



Using the two basic concepts described earlier (the gas flowing 

 over tubes and hydrogen flowing through the tubes) the hydride can be 

 cooled. In cooling as in heating more probleas arise with Bagnesius- 

 nickel hydride than with iron-titanium or lanthanum-pentanickel. Two 

 factors must be taken into account in cooling these hydrides: the 

 temperature at which the hydride must be caintained and the rate at 

 which the hydrogen must be absorbed. Different methods must be used to 

 cool a hydride that must be maintained at a temperature above the boil- 

 ing point of water than co cool one which can be cooler. More problems 

 arise in a system that has to be cooled in a very short period of time 

 than in one which is allowed a longer tiise. 



For iron-titanium and lanthanum-pentanickel the probleas are 

 similar because the temperatures are similar, and the most advantageous 

 system would appear to be similar to the first concept. Large amounts 

 of water can be passed over the tubes which contain the hydride and the 

 heat carried away in the form of heated water. The period of time 

 needed for the recharge can be varied by increasing or decreasing the 

 rate of water passing over the tubes and the rate of hydrogen passing 

 into the tubes. The heated water can then be used where heat is needed 

 elsewhere. If a long period Is available for recharge, air can be blown 

 over the tubes and used for forced air heating. 



For magnesium-nickel hydride, where the temperatures are higher, 

 water could be sprayed into the containment with forced air thus creat- 

 ing a steaa of about 250° to 300°F. This steam could be used for many 

 purposes including water heating and building heating. It would be hot 

 enough to run absorption cooling systems. Calculations show that approx- 

 imately 2 gallons of water would be boiled for every pound of hydrogen 

 absorbed. This method could be used In both fast and slow recharge 

 conditions. In the slow recharge condition air could be blown over the 

 tubes and used for forced air heating. A better method might be to use 

 the second concept though. In this method hydrogen would be added 

 through the access port and passed with the circulating hydrogen through 

 a heat exchanger where it is cooled. Then it would be pumped through 

 the hydride container where it would both absorb heat and be partially 

 absorbed by the hydride. The advantage of this system is that the 

 hydrogen would moderate so that the hydride would not get too cold and 

 thus slow its absorption rate. Water could be sprayed in the hydrogen 

 heat exchanger in this system also, to proouce a mild grade steam. 



37 



