Flow boiling heat transfer with the refrigerants R-134a and R-245fa in copper microchannel cold plate evaporators is investigated. Arrays of microchannels of hydraulic diameter 1.09 mm and 0.54 mm are considered. The aspect ratio of the rectangular cross section of the channels in both test sections is 2.5. The heat transfer coefficient is measured as a function of local thermodynamic vapor qua...

Nomenclature a = stoichiometric coefficient av = surface-to-volume ratio C;, Cb; = surface and bulk concentration, vol % Da = Damkohler number Eif R = activation energy, K F = steady-state function h = heat-transfer coefficient K, = adsorption equilibrium coefficient k, k0 = reaction rate constant and preexponential factor, respectively kc = mass-transfer coefficient l = apparent reaction order...

Oxygen gas-liquid mass transfer coefficient was measured in a gas-induced pulsating flow bubble column. Pulsating amplitude had a great influence on kla under pulsating state of equal base flow and pulsating flow, which was enhanced up to 30 % compared with that under steady state; however, it had a negative effect on mass transfer under a fixed low base flow. It was also found that kla had a n...

Overall liquid side volumetric mass transfer coefficient kLa was determined experimentally for cocurrent Taylor flow moving upwards in a glass tube of an internal diameter of 3mm. Experiments were performed for physical absorption of oxygen in 20% aqueous solution of ethanol. Shadowgraph technique was deployed for precise measurements of bubble lengths and velocities. Experimental values of vol...

............................................................................................................................................... 18 INTRODUCTION......................................................................................................................................... 18 EXPERIMENTAL METHODS ...............................................................................

Parameters governing the rates of mass transfer of the individual components of four synthetic dense non-aqueous phase liquid (DNAPL) mixtures into the aqueous phase were evaluated. The DNAPL mixtures, composed of toluene and eight polynuclear aromatic hydrocarbons (PAHs), were designed to serve as models for coal tars and creosotes. The reactor employed provided a relatively stable interface b...

The evaporation heat transfer and pressure drop characteristics of HFC-161 in a horizontal smooth tube with an inside diameter of 9 mm was experimentally investigated. The local heat transfer coefficient and total pressure drop were measured at the heat flux ranging from 15 – 25 kW/m, the mass flux ranging from 100 – 200 kg/(m·s), and the evaporation temperature of 5, 10 °C. The experimental re...

Nucleate pool boiling heat transfer coefficient have been experimentally measured on a horizontal rod heater for various liquid binary mixtures. Measurements are based on more than three hundred data points on a wide range of concentrations and heat fluxes. In this investigation, it has been confirmed that the heat transfer coefficient in boiling solutions are regularly less than those in p...

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...

in this work, experimental kinetics data of methane hydrate decomposition at temperatures ranging from 272.15 to 276.15 k and at pressures ranging from 10 to 30 bars were modeled by using chemical affinity. this model proposed a macroscopic model which is independent of any intermediate mechanism like heat or mass transfer. the results show there is good agreement with experimental data. also t...