Heat Transfer Mechanism Study of an Embedded Heat Pipe for New Energy Consumption System Enhancement

Abstract

Aiming at the demand for new energy consumption and mobile portable heat storage, a gravity heat pipe with embedded structure was designed. In order to explore the two-phase heat transfer mechanism of the embedded heat pipe, CFD numerical simulation technology was used to study the internal two-phase flow state and heat transfer process of the embedded heat pipe under different working conditions. The evolution law of the internal working medium of the heat pipe under different working conditions was obtained. With the increase in heating power, it is easier to form large bubbles and large vapor slugs inside the heat pipe. When the heating power increases to a certain extent, the shape of the vapor slugs can no longer be maintained at the bottom of the adiabatic section, and the vapor slugs begin to break and merge, forming local annular flow. When the filling ratio (FR) is relatively low, the bubble is easy to break through the liquid level and rupture, unable to form a vapor slug. With the increase in FR, the possibility of projectile flow and annular flow in the heat pipe increases. Under the same heating power, the temperature uniformity of the heat pipe becomes stronger with the increase in heating time. The velocity distribution in the heat pipe is affected by the FR. The heating power has almost no effect on the distribution of the velocity field inside the heat pipe, but the maximum velocity is different. At an FR of 30%, there are two typical velocity extremes in the tube near positions of 120 mm and 160 mm, respectively, and the velocity in the tube is basically unchanged above a position of 200 mm. There are also multiple velocity extremes at an FR of 70%, with the maximum velocity occurring near 240 mm.

Keywords

• new energy consumption
• embedded heat pipe
• vapor–liquid two-phase flow
• CFD numerical simulation
• filling ratio