Heat absorbing capability characterization of loop heat pipe model’s with variation of filling ratio

Abstract

The dissipation of residual heat from decay when a nuclear installation experiences a failure of the active cooling system must continue to be carried out so that its operation remains safe. The passive cooling system in the form of loop heat pipe (LHP) technology has the potential to be used as one of the technologies for extracting the residual heat from the decay. The purpose of this study is to obtain the optimal working area of the characterization of the LHP model to take heat based on variations in the LHP filling ratio. The filling ratio of the LHP must be appropriate to a given heat load and coolant velocity to produce a continuous natural circulation in the heat pipe. The filling ratio has a maximum and minimum limit value. The method used is to operate the LHP model with various filling ratios of 20, 40, 60, 80, and 100%. The LHP model evaporator is immersed in a pool of hot water at 65°C. At the fin in the condenser, the air is blown at a speed of 2.5 m/s. This LHP model has an initial pressure of -74 cm Hg and contains demineralized water as a working fluid. The results obtained indicate that the LHP model with a filling ratio of 100% has the most optimal work area to remove the heat compared to other filling ratios. These results indicate that the amount of heat applied to the evaporator results in optimal LHP heat transfer for 100% fluid volume. This is because the amount of fluid with a filling ratio of 100% produces a more aggressive boiling and then the latent heat is discharged to the environment through the fin. The conclusion of this study shows that to produce optimal heat transfer, the amount of working fluid that is inserted is directly proportional to the heat load given to the evaporator. The results of this characterization can be used as one of the initial knowledge in designing large-scale LHP as a candidate for additional passive cooling systems in water pools that immerse the NuScale type reactor.