In this paper the heat transfer characteristics of a two-phase closed thermosyphon over a wide range of heat transfer rates, system pressure, aspect ratios and filling ratios were studied. The experiments focused on the boiling and condensation heat transfer characteristics of the thermosyphon. The experimental boiling and condensation heat transfer coefficients inside the thermosyphon were com...

In this paper the heat transfer characteristics of a two-phase closed thermosyphon over a wide range of heat transfer rates, system pressure, aspect ratios and filling ratios were studied. The experiments focused on the boiling and condensation heat transfer characteristics of a thermosyphon with a copper tube having 25 and 32 mm inside and outside diameters. Distilled water was used as the wor...

In this study, condensation heat transfer coefficients of R-410A were obtained in flattened stainless tubes made from 5.0 mm inner diameter round tubes. The test range covered saturation temperature 45 , heat flux 10 °C kW/m, mass flux 100~400 kg/ms and quality 0.2~0.8. Results showed the effect of aspect ratio on condensation heat transfer coefficient was dependent on the flow pattern. For ann...

This second part of a two-part study concerns heat transfer characteristics for FC-72 condensing along parallel, square micro-channels with a hydraulic diameter of 1 mm, which were formed in the top surface of a solid copper plate. Heat from the condensing flow was rejected to a counter flow of water through channels brazed to the underside of the copper plate. The FC-72 condensation heat trans...

Forced convective condensation in vertical channel is investigated numerically. The condensation boundary layers that occur due to temperature difference between the walls and saturation temperature of steam is simulated by the volume of fluid (VOF) method. The effect of variations in the hydraulic diameter, steam velocity, Re number and temperature difference between the wall and saturation te...

In the case of multi-component condensation the ‘condensing vapour contains a mixture of components having different boiling points, which condense over a wide temperature range, either in presence of or absence of non-condensing material. In this work, a design algorithm for the condensation of a multi-component vapour mixture in shell side of a shell and tube vertical condenser has been devel...

The condensation heat transfer characteristics of nonazeotropic mixtures R1234yf and R32 (mass fractions of 0.52:0.48 and 0.77:0.23, respectively) inside a horizontal smooth tube (inner diameter 4 mm) were experimentally studied at mass fluxes ranging from 100 to 300 kg/m s. A prediction model for the forced convective condensation heat transfer characteristics of nonazeotropic refrigerant mixt...

In the present study, the condensation and evaporation heat transfer performance of a zeotropic refrigerant mixture (HFC32/HFC125/HFC134a) inside horizontal tubes with smooth, grooved or cross·grooved inner surfaces was investigated experimentally. The cross-gTOoved tube showed the highest heat transfer coefficient for both condensation and evaporation with the zeotropic mixture. Its heat trans...

Enhancing condensation heat transfer is important for broad applications from power generation to water harvesting systems. Significant efforts have focused on easy removal of the condensate, yet the other desired properties of low contact angles and high nucleation densities for high heat transfer performance have been typically neglected. In this work, we demonstrate immersion condensation on...

The condensation heat transfer coefficient of R134a was experimentally studied inside two smooth and four micro-fin tubes. The working conditions and structural parameters of the test tubes were selected as the influencing factors, and the experiment was conducted under mass velocities of 400–1100 kg·m−2·s−1, condensation temperatures of 35–45 ◦C and water-testing Reynolds numbers of 8000–22,00...