Proposal, transient model, and experimental verification of loop heat pipe as heating device for electric-vehicle batteries
Masakazu Hashimoto, Yuki Akizuki, Koki SATO, Ai Ueno, Hosei Nagano
Abstract
This paper reports design, fabrication, and experimental results of a loop heat pipe (LHP) as a heating device for batteries of electric vehicles. Usually, LHPs are used as a cooling device. In this study, however, the LHP is used as a heating device by attaching battery blocks which are the heating target, to the condenser of the LHP. A new transient analytical model was also constructed using the implicit method, which is a multidimensional extension of the Newton–Raphson method. The analytical results are compared with the test results from the point of the transient behavior of the heating LHP. A cylindrical type evaporator with an outer diameter of 27 mm and a length of 150 mm was used. A flat perforated tube with a length of 1625 mm was used as the condenser. R 134a was selected as the working fluid. The condenser of the LHP is connected to the simulated battery blocks, which were made of 48 aluminum-alloy blocks (100 × 128 × 26.5 mm). First, the operation test was conducted at room temperature, and the basic thermal performance and the concept of the battery heating were evaluated. Next, the experiment was conducted in a thermostatic bath which was set at −20 °C. The experimental results showed the simulated battery blocks reached above 0 °C at 14,600 s. The temperature increase rate was estimated to be 0.06–0.09 °C/min, and it can be considered that this LHP can be used as a heating device under actual low-temperature conditions.