New High Temperature Absorbent for Absorption Heat Pumps. Final Report.

摘要

A new absorption working pair (AWP) for absorption heat pumps has been identified which provides higher temperature capability (260 deg C), higher lifts, and use of lower cost construction materials, than currently available absorption heat pump working fluid pairs (e.g., LiBr-H sub 2 O). Using water as working fluid, the absorbent is a ternary mixture of LiNO sub 3 , KNO sub 3 , and NaNO sub 3 in the preferred proportions of 53, 28, and 19 weight percent, respectively. In addition to being thermally stable above 260 deg C, it promotes the formation of a passive and protective corrosion resistant oxide film on both mild steel and all stainless steels. The thermodynamic, corrosion, and stability properties of this new absorbent have been measured. At temperatures of 260 deg C and higher the absorbent has negligible thermal decomposition, has corrosion rates less than 1 mil/year for both carbon steel and austenitic stainless steel, and provides practical heat pumping lifts of up to 90 deg C. (ERA citation 11:036147)