Mass transfer coefficient

About: Mass transfer coefficient is a research topic. Over the lifetime, 7827 publications have been published within this topic receiving 168354 citations.

The Effective Diffusion Coefficient and Mass Transfer Coefficient of Nordic Softwoods as Calculated from Direct Drying Experiments

Abstract: The effective diffusion coefficient and mass transfer coefficient of Scot's pine and Norway spruce heartwood are calculated from the measured development of the internal moisture profiles of sawn timber during drying. Measurement is made using the oven-dry method. Calculation of both coefficients is based on using an existing timber drying simulation model to iteratively optimise the parameter values for the diffusion and mass transfer coefficients of prescribed functional form. The results show that the procedure employed is a feasible method to obtain numerical values for the internal and external transfer coefficients as functions of wood moisture content and temperature. The resulting diffusion coefficient and mass transfer coefficient are applicable in the whole moisture range between green and dry states in temperatures 20-80°C thus covering the whole process of medium-temperature wood drying.

Effect of Stirring Energy, Temperature and Flux Composition on Hot Metal Dephosphorization Kinetics

Abstract: In order to extend the applicability of a coupled reaction model to the hot metal dephosphorization process, evaluation method for unknown parameters was investigated. The following points were clarified.(1) Mass transfer coefficient in metal phase was increased in proportion to e1/2 and its activation energy was about 125 kJ/mol.(2) Ratio of mass transfer coefficient in metal phase to slag phase did not clearly depend on stirring energy, temperature, or flux composition.(3) Phenomenological rate parameter for CO evolution also did not clearly depend on stirring energy or flux composition but decreased with an increase in temperature.(4) Activity coefficients of FeO and P2O5 in CaF2 and CaCl2 containing oxide slag were able to be estimated by a regular solution model in which the interaction energy was expressed as a function of the CaF2, CaCl2 content.By the application of these results to the coupled reaction model, the change of concentration during the hot metal dephosphorization experiments was calculated without using a parameter fitting method.

Experimental study on condensation heat transfer and pressure drop of low GWP refrigerant HFO1234yf in a horizontal tube

Abstract: Condensation heat transfer of low GWP refrigerant HFO1234yf was measured in a horizontal tube (inner diameter: 4 mm) at a mass flux range of 100–400 kg m −2 s −1 and different saturation temperatures (40, 45, and 50 °C), and the results were compared with that of R134a and R32. Effects of mass flux, vapor quality, saturation temperature, and thermophysical properties on the heat transfer coefficient were analyzed. Mass flux and vapor quality were presented to primarily affect the heat transfer coefficient in shear-force dominated flow regimes, whereas the thermal conductivity and density ratio are the primary parameters as thermophysical properties influencing the heat transfer coefficient. Observed annular flow regimes agreed with Tandon’s flow pattern map. The measured pressure drop compared with that predicted by the Lockhart–Matinelli correlation, Huang correlation and Haraguchi correlation. And, when comparing the experimental heat transfer coefficient with four heat transfer coefficient correlations, the Haraguchi correlation fairly agreed with the experimental data, with a 10.8% mean deviation.