Pham Quang Vu

A General Correlation to Predict The Flow Boiling Heat Transfer of R410A in Macro/Mini Channels

This study demonstrates a general correlation to predict the saturated flow boiling heat transfer of R410A in horizontal macro- and mini-channels. The experimental data were observed in various tube diameters of 1.5, 3.0, 6.61, and 7.49 mm, mass fluxes of 100–600 kg/m2s, heat fluxes of 10–40 kW/m2, saturation temperatures of 5°C–15°C, and vapor qualities from 0.2 to 1. The database was compared with numerous well-known correlations. The proposed correlation was based on the superposition model of nucleate boiling and forced convective boiling contribution. The new modified correlation showed a good prediction against the present database.

An Experimental Investigation of Condensation Heat Transfer Coefficient of R-410A in Horizontal Circular Tubes

Condensation heat transfer has been evaluated experimentally on the tube side of three different circular tubes with inner diameter of 6.2, 7.5 and 9.2mm, respectively. Two-phase fluid flow conditions include mass fluxes from 200 to 320kg/m2s, qualities between 0.1 to 0.9, and heat flus range of 5 to 20kW/m2 at a fixed saturation temperature of 48°C. Results showed that the average heat transfer coefficient increased with the increase of vapor quality, mass flux and heat flux, but decreased with inner diameter. The experiment results are compared with the existing heat transfer coefficient correlations, and a new correlation is developed with good prediction.