Empirical Correlation for an Ammonia Charged Aluminum Closed Loop Pulsating Heat Pipe

Pulsating Heat Pipe (PHP) has become one of the promising options for passive heat transfer. This technique is especially efficient for cooling of micro and nano sized particles. This paper works on a aluminum made and ammonia charged pulsating heat pipe. The heat pipe consists of aluminum tubing having total 14 turns of 3mm and 4mm as inner and outer diameter. A constant electric power supply of 36 W was provided to run the pulsation mechanism. The experiment was carried out for three filling ratios of 0.4, 0.6 and 0.8 as well as inclination angle of 30°, 45°, 60°, 90° and 180°. The objective of this research is to formulate an empirical correlation between overall heat transfer coefficient and different physical parameter such as heat input, evaporator temperature rise, fill ratios and inclinations. It has been found that the correlation is effective for heat input and filling ratios. Experimental results showed that for these two parameters the correlation converges well.