Effects of heating/cooling-water temperatures on output power characteristics of forced cooling pulley-type SMA heat-engine

In this research, the effects of heating/cooling water temperatures of a heat engine on the output characteristics of the forced cooling pulley-type SMA heat-engine is investigated for the purpose of operating temperature optimization of the engine. The engine output increases almost linearly as the heating water temperature (TH) rises. On the other hand, the engine output shows a gradual decrease as the temperature of SMA element during cooling (TSMA) rises to 321.4 K and then an abrupt decrease when the TSMA = 322.7 K. Thermal cycling tests under constrained strain conditions for the SMA element were carried out to investigate the effect of heating/cooling temperatures to generation stress () and reaction velocity (VR) of the SMA element. In result,  increases gradually with the increase of TH. Besides, VR increases almost linearly as TH increases. This result suggests that the increase of engine output as TH increases is mainly due to the increase of the VR. Meanwhile, VR increases gradually with the increase of TSMA. Besides,  increases as TSMA rise up to 318 K, above which it decreases rapidly. From these results, it may be concluded that the contributing factor to the engine output is the variation of  and VR with the variation of TSMA.