Papers by Keyword: Thin Film Evaporation

Abstract: The heat transfer and fluid flow performances of thin film evaporation were investigated numerically in this paper. Based on the coordinate transformation and the Galerkin Method, the analytical solutions of the temperature and pressure distribution within the meniscus bulk region, where the interface is dominated by surface tension were found. The effects of contact angle, superheat and aspect ratio on the temperature distribution of thin film evaporation in the rectangular groove were studied. Meanwhile, the pressure and velocity distribution of thin film evaporation were calculated and analyzed. The results had investigated in this paper can help understanding the mechanism of thin film evaporation for the further study.

Abstract: Thin film evaporation is a kind of high efficiency heat transfer. A thin film evaporator with rectangular micro groove has been designed, constructed and tested. The heat flux, superheat and thermal resistance of the thin film evaporator were investigated under different evaporating temperatures. Compared with the regular evaporator at the same condition, the thin film evaporator with rectangular micro groove has a better heat transfer performance and good temperature uniformity. The experimental investigation presented in this paper can be used as a reference to promote the engineering application and development of the thin film evaporator.

Abstract: The recent interest in boiling heat transfer in small diameter tubes has led to the study of boiling heat transfer outside a compact tube bundle of diameter 3mm. The bank comprised 3 columns each of 10 stainless steel electrically heated tubes of 3mm outside diameter, with pitch to diameter ratio of 1.5 in an in-line arrangement. These tests were carried out using distilled water and R113 at nominal atmospheric pressure over a range of heat fluxes between 4-21 kW/m2 for mass fluxes from G=5.6 - 32.8 kg/m2s. The recent three-zone evaporation model developed by Thome, Dupont and Jacobi for boiling inside micro channels was used to compare with experimental results as photographic study showed that bubbles confined within the bundle were responsible for the heat transfer enhancement observed. It was observed that the three state model was promising in its application to the bundle arrangement as the confinement number Co for bundle has been shown to be in the order of 0.63