DURABILITY TO REPETITIVE REACTION OF MAGNESIUM OXIDE WATER REACTION SYSTEM FOR A HEAT-PUMP/

The feasibility of using a magnesium oxide/water system in a heat pump was examined experimentally From the viewpoint of enhancing the durab ility of the repetitive reaction cycle and increasing the heat output performance. Three kinds of magnesium oxide materials tested in this s tudy were formed using the following precursors: ultra fine magnesium oxide powder, common magnesium hydroxide and magnesium ethoxide. The r eaction cycles for both hydration and dehydration of the magnesium oxi de materials were examined in each experiment. A new magnesium oxide m aterial using ultra fine magnesium oxide powder as the precursor was t he most appropriate material for the heat pump, because it exhibited h igh durability and high heat output performance compared to the other oxides. Although reactivity of the new material decreased during the i nitial five reaction cycles, the reactivity remained relatively consta nt over the next 19 cycles. Based on the experimental results, the the rmal performance of a heat pump using the new material was simulated n umerically. The new material produces an outputting of 180 W/kg after 24 repetitions over a 15-min period. It was concluded that the high du rability of the new material was due to the high purity of the startin g materials. (C) 1997 Elsevier Science Ltd.