K. Kaneko, K. Enomoto, Tokyo University of Science, Tokyo, Japan
This research aims at developing the heat engine system using Shape Memory Alloy (SMA) wires, which works by alternating supply of hot/cold water through the newly developed automatic valves. The SMA wire is connected to the chain and sprocket system with the ratchet type bearing and the spindle with the flywheel. The valve for supplying hot/cold water to the SMA wire is driven by the flywheel, so no power from outside is necessary. Output power of the developed heat engine using two φ0.3 mm SMA wires is 0.1W at 30~40 rpm. The SMA wire used in the developed heat engine is produced by the Furukawa Electric Co., Ltd. and 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 a water supplying timing. The stress of the SMA is kept almost constant during working because that the system has no crank system. So, the developed heat engine system is hopeful to use in recovering energy from waste hot water.
Summary: The heat engine system is developed using Shape Memory Alloy (SMA) wires, which works by alternating supply of hot/cold water. In the system, two straight SMA wire change in length alternatively by transformation and make the flywheel and the dynamo rotary, through the ratchet type bearing system. The valve for supplying hot/cold water to the SMA wire is driven by the flywheel, so no power from outside is necessary. Output power of the developed heat engine using two ö0.3 mm SMA wires is 0.1W at 30~40 rpm. The SMA wire used in the developed heat engine shows the fatigue life of more than 100,000 cycles under conditions of 150 MPa in loading and heating/cooling cycle rate of 0.5 Hz in the cyclic transformation fatigue tests. So, the developed heat engine system is hopeful to use in recovering energy from waste hot water.
Key words: Shape Memory Alloy, Reciprocating heat engine, Ratcheting system, Energy recovering, Dynamic transformation property of SMA, Fatigue in cyclic transformation
