WORKING CHARACTERISTICS OF A RECIPROCATING-TYPE HEAT ENGINE USING SHAPE-MEMORY ALLOYS

Various types of heat engines using shape memory alloys are proposed a nd studied. From the viewpoints of thermal efficiency and operational control of an engine, an efficient heat exchanger is required for heat ing and cooling shape memory alloys. Furthermore, a heat engine operat ing in a small range of strain is required because the fatigue life of shape memory alloys is strongly dependent on the strain-of shape memo ry alloys. In this paper, a novel operation system comprising of a rec iprocating-type heat engine using shape memory alloys was proposed. Th is proposed engine could be operated continuously even within a small strain range. The shape memory alloys used were straight wires of a Ti NiCu alloy which were heated and cooled by forced convection. The work ing characteristics of the engine were investigated by experiment. Exp eriments were conducted at various heating temperatures and under vari ous strains. Working characteristics such as the amount of work are di scussed.