Heat transfer predictions for helical oscillating heat pipe heat exchanger: Transient condition

Abstract

The transient temperature profiles of a Helical oscillating heat pipe (HOHP), the heat transfer profiles of the HOHP, and the heat transfer profiles of a HOHP heat exchanger during start-up operation from a numerical model and from an experiment were studied. This article presents the details of a calculation for the HOHP, in which the HOHP has a domain consisting of a pipe wall and a vapor core. The governing equation at the pipe wall and the vapor core of the HOHP was solved by a numerical method. The numerical solution for the transient model in this study was obtained using a finite difference method, and the finite difference method used in this study was the Clank-Nicolson method. The temperature at the pipe wall of the HOHP, the heat transfer of the HOHP, and the heat transfer of the HOHP heat exchanger were plotted as functions of time. The results show that the transient temperature distributions at the pipe wall of the HOHP from the numerical model were successfully compared with the results from the experimental data, which utilizes the concept of temperature distributions during transient operation. The steady state temperature profiles were obtained as a steady temperature was input into the outer wall at the evaporator section of the HOHP. This study also found that the transient heat transfer profiles of the HOHP from the numerical model were successfully compared with the results from the experimental data, which utilizes the concept of heat transfer increments in the HOHP during transient operation. Moreover, it was also found that the transient heat transfer profiles of the HOHP heat exchanger from the numerical model were successfully compared with the results from the experimental data. Therefore, it can be concluded that the numerically validated temperature distributions of the HOHP, the heat transfer of the HOHP, and the heat transfer of the HOHP heat exchanger were successfully simulated in this model.