Hydride heat pump

The reversibility of the metal-hydrogen reaction (Eq. l) and the heat of chemical reaction (Eq. 2) provides the basis for hydride heat pumps. These devices are closed units in which hydrogen serves as an energy carrier between two or more hydride beds. By selecting appropriate hydriding alloys, heat sources and heat sinks, heat can be pumped over wide temperature differentials with no moving parts except possibly check valves. 

Figure 17. Schematic hydride heat pump cycles...

DOE, through Brookhaven National Laboratories, has recently issued a contract for an industrial team to design, build, and test a prototype metal hydride heat pump for residential, commercial or industrial applications. This three-year program is intended to assess the commercial viability of this technology. 

Efficiency of HHP in a refrigerator cycle as the relation of a useful cold to the spent heat Hydride heat machine, hydride heat pump... 

Keywords hydride, hydrogen, hydride bed, hydride sorber, hydride heat pump. 

Application of hydride heat machines (the HHM - the hydride heat pump (HHP), a refrigerator, a heat transformer, the compressor, the accumulator of hydrogen) is justified there where there are sources of low-potential energy or a plenty of wasted heat is not used. Systems hydrogen-metal hydrides promote improvement of ecological conditions and introduction of cleaner hydrogen technologies. 

Present is enough the big global experience of construction of multistage hydride heat pumps. Here there is no opportunity in detail to analyse all features inherent in such pumps. We shall draw attention only to some integrating reasoning. 

Shanin, Yu.I. (2002) Simulation of hydride heat pump operation with reference to vehicle refrigerating devices. - In Veziroglu TN, Zaginaichenko SY, Schur DV, Trefllov VI editors/Hydrogen Materials Science and Chemistry of Metal Hydrides. NATO science series. Series II Mathematics, Physics and Chemistry, 82, 97-106. 

High- and Low-Temperature Hydrides Hydride Heat Pump... 

Metal hydride sorbers were in a composition of experimental installations [4, 5] based on the metal hydride heat pump. Here we shall consider in detail features of one of installations for cold generation [4] (Fig. 3) using waste heat - hot water with temperature 80-90°C - as an energy source simulator. 

The main units of installation are sorbers forming two units of a metal hydride heat pump. Sorbers of the first unit are modular-type. Modules of the first unit sorbers have seven thin-walled steel tubes 25 mm in diameter. When installation works, water is run through a sorber case and flow around external surface of modules heating or cooling them. 

Mathematical model and a set of programs for computer modelling of hydride heat pumps work had been developed earlier by one of authors [6]. The system of... 

Astahov, B.A., Afanasjev, V.A., Bokalo, S.J., et al. (1999) Creation of smallsized refrigerating installations with a metal hydride heat pump. - 6th NATO Int. Conf. Hydrogen Material Science and Chemistry of Metal Hydrides ", ICHMS 99. Abstract Book of NATO International Conference. Katsiveli, Yalta, Ukraine, September 02-08, 1999, 306-307 (in English and Russian). 

In this article the one-stage hydride heat pump is discussed only with the purpose of optimization of some the factors influencing efficiency, specific output power and important at estimation of operation and power efficiency. 

For the developed mathematical model of HHP alternative calculations have been carried out with the purpose of search of optimum values of regime parameters for concrete installations [7, 8], It has been determined, that there are optimum initial pressure in sorbers of HHP, optimum temperature modes (at levels of temperatures Th, Tm, T ), providing the maximal efficiency. Optimization of control by HHP operation it is possible to achieve optimum characteristics of capacity and to choose necessary duration of a cycle of HHP. Control of the hydride heat pump is its essential part and as show the carried out calculations [7, 8], essentially influences efficiency of its operation. Experimental results basically have proved mathematical calculations. 

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