A Shape Memory Alloy Thermal Engine for Waste Heat Recovery

Concern for the well-being of our planet and mankind's ever-expanding need for power has generated considerable interest in alternative ways of generating power. Many different methods of producing power, such as fuel cells, wind turbines and solar panels, have been developed and refined in recent years. The Shape Memory Alloy heat engine, discussed in this work, is also a result of this growing interest in the quest for alternative power sources. In this paper we present a novel approach to arranging shape memory alloy (SMA) wires into a functional heat engine. Significant contributions include the design itself, a preliminary analytical thermal analysis and the realization of a research prototype; thereby, laying a foundation from which to base refinements and seek practical applications. The proposed engine consists of a set of SMA wires stretched between a fix point and a connecting rod mounted on a freewheel who act on a shaft rotating in one direction. During operation, the wires are alternatively heated with water at a temperature of 358 K, in order to obtain the contraction of the wires, and refrigerated with air at room temperature (293 K), to aloud the deformation of the wires. Potential applications may include the conversion of waste heat into shaft power.