| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
For use of oscillating heat pipes (OHPs) in a space environment, in addition to a high performance, it is very important that they work in a wide range of conditions, temperature and heat input. In this research, wick was inserted to the OHP (I.D.=φ1.5mm) to expand this range of conditions. The wicked OHP worked well at a range of higher input power, where a OHP without wick didn't work. But at a middle range, the wicked OHP's effective thermal conductivity became lower than that of the normal OHP. If wicks were inserted in a symmetrical configuration, circulating flow didn't occur and OHP didn't worked well. Although a normal OHP of 2mm I.D. didn't work, the wicked OHP worked well and showed a good performance.
The OHP showed a better performance both without a wick in a vertical-bottom-heating operation, and with a wick at half-length of overall OHP in a horizontal operation using ethanol as the working fluid. The OHP performance with or without wick was investigated by extending the adiabatic section length from 270 to 1000 mm. In a horizontal operation, the wicked OHP worked well and showed a good performance with the adiabatic section 270 or 500 mm in length. Furthermore, for practical space use, the OHP using ammonia as the working fluid was investigated in the lower temperature region. The ammonia OHP without a wick showed higher performance than the ethanol OHP in a vertical operation. In a horizontal operation, the wicked ammonia OHP worked well, but unstably in the case of higher thermal input power.
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