On the Test Setting at Condenser in Thermal Performance Tests of Heat Pipes

This work compares the heat pipe test results using different test settings at the condenser under an identical evaporator setting and operating temperature of 45°C at the adiabatic section. The first test setting, considered as the standard, adopts a pair of water-cooled cold plates in which the heat pipe condenser is embedded, with a number of thermocouple beads attached to the condenser wall. In the second setting, the condenser resistances are determined based on the wall temperatures measured outside either end of the cold plate. The third setting adopts a water jacket with a number of thermocouples attached to the condenser wall but exposed to the cooling water. These three test settings have been applied in the literature. The second setting fails to count in the thermal resistances across the wick and pipe wall, and thereby seriously under-estimated the condenser resistances. For the third setting, the temperature readings are lowered by the cooling water so that the condenser resistances are greatly over-estimated. However, a fourth setting with the cooling-protected thermocouples yields similar results obtained using the standard setting. These results suggest that thermocouples be suitably arranged to ensure reliable performance measurements for the heat pipe condenser.