Development of Reciprocating Heat Engine Using Shape Memory Alloy

Abstract

This research aims at developing the heat engine system using Shape Memory Alloy (SMA) wires, which work by alternating supply of hot/cold water through the newly developed automatic valves. The SMA wire is connected to the chain and sprocket system having the ratchet type bearing and the spindle with the flywheel. The valves for supplying hot/cold water to the SMA wires are driven by the flywheel, so no outside power is necessary. Output power of the developed heat engine with two φ 0.3 mm SMA wires is 0.1W at 30∼40 rpm. The SMA wire used in the developed heat engine was produced by the Furukawa Electric Co., Ltd.. The wire shows the fatigue life of more than 105 cycles under conditions of 150 MPa in loading and heating/cooling cycle rate of 0.5 Hz in the cyclic transformation fatigue tests. The heat engine system works without any adjusting process of a length of SMA wire and water supplying timing. The stress of the SMA wire is kept to be rather higher during working because that the engine has no crank system. So, the developed heat engine system is hopeful to use in recovering energy from waste hot water.