A mathematical model to investigate the effects of the ambient and condenser temperatures on the performance of a loop heat pipe

A loop heat pipe is a passive device, which can be used for cooling of different systems. In the space applications and in the absence of the gravity, the heat pipe is an attractive device for cooling the electronic and optical devices, because of its high reliability. In the present study, the effects of two parameters, including the ambient and condenser temperatures, on the performance of the loop heat pipe are investigated through the mathematical modeling. A loop heat pipe with nickel wick, cylindrical evaporator, and ammonia as its working fluid is examined in the power range of 20 to 350W. The validation results show that there is a good agreement between the experimental and mathematical results in the power range of 90 to 350 W. Heat transfer between reservoir the and the ambient affect the working temperature and the steady-state performance of the system. By reducing the ambient temperature for 300 to 280 K with the condenser temperature of 273 K, the working temperature is reduced up to 12K in the heat loads between the 20 to 100 W. However, this reduction in the working temperature is vanished by increasing the heat loads to 350W. By reducing the ambient temperature for 300 to 280K, the length of the two-phase region of the condenser is decreased, which leads to a reduction from 350 to 150W in the steady state process.