Watkins, Dunbar & Pollick
Absorption refrigeration and heat pump system with defrost
 An integrated three-chamber absorption refrigeration and heat pump system with improved defrost capabilities having a solution pair including a material of .[.unusable.]. .Iadd.unusual .Iaddend.fluid stability at higher temperatures when manipulated in an apparatus and system to take advantage of its properties. Disclosed materials of a solution pair for operation as part of the system of this invention are ammonia as the refrigerant and sodium thiocyanate as the absorbent. A heat transfer sub-system is provided, for conveying a working fluid between the components, having multiple switchable valve means, including first, second, and third valve members selectively switchable to convey the working fluid from the cooling mode to the heating mode and vice versa, as well as to the defrost mode. 
Columbia Gas Service Corporation
Bert F. Stephen
Cook Petty