Flow Boiling Heat Transfer in Horizontal Metal-Foam Tubes

Abstract

The two-phase flow and boiling heat transfer in horizontal metal-foam filled tubes are experimentally investigated. The results show that the heat transfer is almost doubled by reducing the cell size from 20 ppi to 40 ppi for a given porosity, thanks to more surface area and strong flow mixing for the smaller cell size. The boiling heat transfer coefficient keeps steady rising, albeit slowly, by increasing the vapor quality for high mass flow rates, while the same story does not hold for the cases of low mass flow rates. The flow pattern can be indirectly judged through monitoring the cross-sectional wall surface temperature fluctuations and wall-refrigerant temperature difference. As the operating pressure increases, the boiling heat transfer at low vapor quality (x<0.1) exhibits similar behavior with pool boiling heat transfer, namely, the heat transfer is enhanced by improving the pressure. However the flow boiling heat transfer is suppressed to some extent as the pressure increases. The heat transfer coefficient of copper foam tubes is approximately three times higher than that of plain tubes.

Analytical considerations of flow boiling heat transfer in metal-foam filled tubes

“…(38), al. [10]. The analytical results are a little higher than the experimental data with a maximum deviation of 25%.…”

“…However, in their model only one-dimensional problem was considered. Zhao et al [10,11] Consequently, analytical model in Mo [4] needs to be improved. In this model, the H-type strut is composed of two circular arcs with a quarter of circular constant radian, as shown in Fig.…”

Heat transfer of phase change materials (PCMs) in porous materials

“…The containers were insulated with asbestos fabric more than 100 mm thick. Five thermocouples were put into the container (5,15,25,35, and 45 mm away from the heating surface) to measure the changes in temperature inside the samples. Another thermocouple was used to record the temperature of the heating surface.…”

“…Thermal transport processes in metal foams, such as forced convection, thermal radiation, and boiling heat transfer, have been extensively studied [18][19][20][21][22][23][24][25]. Although extensive investigations have been conducted on the positive effect of porous materials in low-temperature thermal energy storage applications, few papers have reported the results of PCM/Metal foam and PCM/ expanded graphite composites applied to low and high temperature thermal storage.…”

Numerical Modelling of Flow Boiling Heat Transfer in Horizontal Metal‐Foam Tubes

“…The local heat transfer coefficients for liquid and vapor phases are first examined separately to consider the overall flow boiling heat transfer behaviour in metal-foam tubes by properly considering the presence of metal foam structures. The predicted results are compared with the experimental results [7] for flow boiling heat transfer in metal-foam tubes.…”