In present study, the two phase flow boiling heat transfer coefficient and pressure drop of R410A, R32 and R290 in microchannels are demonstrated. The experimental data were conducted in horizontal stainless steel tubes with the inner diameter of 0.3 mm and 1.5 mm. The testing conditions were performed with the mass fluxes range from 200 to 500 kg/m2s, the heat fluxes from 10 to 20 kW/m2, the s...

plate heat exchangers are widely used in industries due to their special characteristics, such as high thermal efficiency, small size, light weight, easy installation, maintenance, and cleaning. the purpose of this study is to consider the effect of depth, angle, and pitch of hemispheric chevrons on the convective heat transfer coefficient and pressure drop. in the simulation of the heat exchan...

Measuring condensation heat transfer and its associated coefficient is not trivial. Rigorous measurements require careful experimental design tradeoff studies to properly select sensor type, sample geometry size, coolant fluid flow rate, operating conditions, working purity, purge methodology, measurement protocol. Conventional tube-based quantify the change in enthalpy of a single-phase via in...

in the present work, graphene was synthesized by chemical vapor deposition (cvd) method. the structure of graphene was then confirmed by x-ray diffraction (xrd) and scanning electron microscope (tem) images. after that, mixed acid method (h2so4/hno3) was used to make the structure of synthesized graphenehydrophilic. in this method, carboxylate and hydroxide groups were linked to the edges of gr...

The principle of heat transfer enhancement in the core flow of a tube has been proposed, in this paper, to make fluid temperature uniform in the core region of a tube and decrease flow resistance, which is different from heat transfer enhancement in the boundary flow of a tube. Two new models, representing heat transfer enhancement in the laminar and turbulent tube flow, have been established a...

In this study, direct numerical simulation for the bubble condensation in the subcooled boiling flow was performed. The main goal was to develop the CFD modeling for the bubble condensation and to evaluate the accuracy of the VOF model with the developed CFD modeling. CFD modeling for the bubble condensation was developed by modeling the source terms in the governing equations of VOF model usin...