2019 Volume 27 Issue 1 Pages 35-41
Considering application to thermal management of space satellites, heat transport characteristics of an ammoniacharged oscillating heat pipe (OHP) in a low temperature region are investigated experimentally. A 6-turn looped-OHP of 400 mm in length is set in a horizontal position with uniform heat flux heating and a cooled aluminum block. Temperatures are measured at about 100 points with thermocouples to evaluate its heat transport characteristics. In the adiabatic section, the adjacent pipes show different temperature distributions along the axes. One is a uniform distribution and the other is a linearly-decreasing distribution from the heating to cooling section. In the former pipe the fluid flows from the heating to cooling section and latent heat transport may be dominant. The flow direction in the latter pipe is opposite and sensible heat transport by oscillatory flows may be dominant. By changing both the cooling section temperature from -60 °C to -20 °C and the charge ratio from 25 wt% to 73 wt%, we make two heat transfer performance maps: a map on the maximum heat transport rate and a map on the maximum effective thermal conductivity. The peak values of about 60 W and 43 kW/(m∙K) are obtained at around the same conditions: the cooling section temperature of -30 °C and the charge ratio of 54 wt%.