Experimental research on refrigeration characteristics of a metal hydride heat pump in auto air-conditioning

Refrigerating experiments of metal hydride heat pump were conducted under three operating temperatures. The high pressure reaction bed is filled with LaNi4.61Mn0.26Al0.13, while the low pressure reactor is filled with La0.6Y0.4Ni4.8Mn0.2. The results show that there are four processes for high-pressure reaction bed, and three processes for low-pressure reaction bed. The lowest refrigerating temperatures at the three operating temperatures are 6.5, 2.5, and 1.9 degrees C, respectively. Cooling power output cannot be kept constant and becomes smaller as the refrigerating process goes on. As T-h increases, the refrigeration cycle time, temperature and pressure of high reaction beds all climb and COP and cooling power output keep increasing. There is a great deviation between the static van't Hoff plots and the actual dynamic lnP-1000/T relations under the operating temperature of T-h/T-m/T-l = 150 degrees C/30-32 degrees C/20 degrees C. (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.