An outline of the working principle of separated heat pipe loop and its application potential in refrigeration and air conditioning area has been provided herein. A heat pipe loop with seven parallel branches was investigated experimentally for the performance of fuel pool cooling

along with the impact of the liquid filling ratio in the heat pipe loop with R134a as working fluid. Experimental results showed an optimal liquid filling ratio in the heat pipe loop of approximately 42.3%; accordingly

the pool temperature

evaporation temperature in the tube

and heat transfer coefficient increased with a higher temperature inside the water tank within the heating power range of 780–2 560 W. The flow distribution of branches in both evaporation and condensation sections was uneven with a certain difference in heat transfer performance among the parallel branches. The largest heat transfer coefficient was found in the No.1 branch pipe of the evaporation section

which was 1.68 times that of the No.7

with 42.3% liquid filling ratio and 1 680 W heating power.