The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Shengqiang Shen - One of the best experts on this subject based on the ideXlab platform.
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Circumferential distribution of local heat Transfer Coefficient during steam stratified flow condensation in vacuum horizontal tube
International Journal of Heat and Mass Transfer, 2017Co-Authors: Shengqiang Shen, Yaoxuan Wang, Dayuan YuanAbstract:Abstract An experimental system was built up to measure the wetted angle and circumferential distributions of local heat Transfer Coefficient during the steam stratified flow condensation in vacuum horizontal tube. The wetted angle is mainly affected by vapor quality. It decreases with vapor quality and steam mass flow rate, and increases with the steam saturation temperature. The Biberg’s correlation and Rouhani’s void fraction correlation are used together to predict the experimental value of wetted angle accurately. The tube wall is divided into filmwise condensation section and liquid accumulation section by the stratified interface. The local heat Transfer Coefficient in filmwise condensation section is significantly higher than that in liquid accumulation section. The local heat Transfer Coefficient increases with vapor quality and steam mass flow rate for all locations along the circumferential direction. The increase of temperature difference between steam and cooling water causes the decrease of local heat Transfer Coefficient in filmwise condensation section and has less effect on that in liquid accumulation section. With the change of steam saturation temperature, the heat Transfer Coefficients in two sections of the tube appear different variation tendencies. Based on the experimental values, new correlations for local heat Transfer Coefficient of steam condensation flow in stratified flow pattern are proposed.
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three dimensional heat Transfer Coefficient distributions in a large horizontal tube falling film evaporator
Desalination, 2015Co-Authors: Luyuan Gong, Xingsen Mu, Shengqiang Shen, Xue ChenAbstract:Abstract The distributions of the heat Transfer Coefficient in a large horizontal-tube falling film evaporator under different operating conditions were investigated with numerical simulation in this paper based on the distributed parameter model (DPM). The heat Transfer Coefficient distributions along the tube row direction, tube length direction, and tube column direction were analyzed with the brine inlet spray density ranging from 0.05 kg/m s to 0.09 kg/m s and the brine inlet salinity from 30 g/kg to 50 g/kg. Results show that the heat Transfer Coefficient has higher values for the evaporating zone than the preheating zone. With the operating conditions included in this paper, the change of brine inlet salinity leads to a wider variation range of heat Transfer Coefficient along the tube length direction for the evaporating zone than the change of brine inlet spray density. The change of brine inlet spray density leads to a wider variation range of heat Transfer Coefficient along the tube row direction for the first tube pass and along the tube length direction for the preheating zone than the change of brine inlet salinity.
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experimental study of falling film evaporation heat Transfer Coefficient on horizontal tube
Desalination and Water Treatment, 2012Co-Authors: Xingsen Mu, Shengqiang Shen, Yong YangAbstract:Abstract The horizontal-tube falling film evaporation is a widely adopted technique in multiple-effect distillation desalination plant. It has a high heat Transfer Coefficient under quite small temperature difference. In this paper, an experimental equipment for horizontal-tube falling film evaporation was set up. Experiments were carried out to show how the heat Transfer Coefficient is affected by different parameters including heat flux, circumference direction of tubes, spray density, evaporation temperature, and experimental fluid. Results indicate that the heat Transfer Coefficient decreases after a little increase with growth of spray density. The heat Transfer Coefficient decreases along the tube circumference, but at the bottom of the tube, it shows increasing trend. In addition, a simple comparison between seawater and fresh water in heat Transfer Coefficient is also provided.
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space distribution of heat Transfer Coefficient in horizontal tube falling film evaporator
CIESC Journal, 2011Co-Authors: Shengqiang Shen, Luyuan Gong, Gangtao Liang, Rui Liu, Xiaohua LiuAbstract:A set of experimental facilities was set up to measure the heat Transfer Coefficient of horizontal-tube falling film evaporator.The effects of spray density on the topmost row Γ and evaporating temperature T on the overall heat Transfer Coefficient K are studied.The heat Transfer Coefficient distribution in the evaporator is presented.The results indicate that increase of spray density and evaporating temperature helps to enhance the value of K.Along the axial direction of the tube,K increases at the first 5 m and then decreases in the following 3 m,mainly caused by the condensation inside the tube.The K value decreases from the upper rows to the lower rows.In addition,increase of number of tube rows reduces the K value,especially at low spray density.
Xue Chen - One of the best experts on this subject based on the ideXlab platform.
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three dimensional heat Transfer Coefficient distributions in a large horizontal tube falling film evaporator
Desalination, 2015Co-Authors: Luyuan Gong, Xingsen Mu, Shengqiang Shen, Xue ChenAbstract:Abstract The distributions of the heat Transfer Coefficient in a large horizontal-tube falling film evaporator under different operating conditions were investigated with numerical simulation in this paper based on the distributed parameter model (DPM). The heat Transfer Coefficient distributions along the tube row direction, tube length direction, and tube column direction were analyzed with the brine inlet spray density ranging from 0.05 kg/m s to 0.09 kg/m s and the brine inlet salinity from 30 g/kg to 50 g/kg. Results show that the heat Transfer Coefficient has higher values for the evaporating zone than the preheating zone. With the operating conditions included in this paper, the change of brine inlet salinity leads to a wider variation range of heat Transfer Coefficient along the tube length direction for the evaporating zone than the change of brine inlet spray density. The change of brine inlet spray density leads to a wider variation range of heat Transfer Coefficient along the tube row direction for the first tube pass and along the tube length direction for the preheating zone than the change of brine inlet salinity.
Luyuan Gong - One of the best experts on this subject based on the ideXlab platform.
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three dimensional heat Transfer Coefficient distributions in a large horizontal tube falling film evaporator
Desalination, 2015Co-Authors: Luyuan Gong, Xingsen Mu, Shengqiang Shen, Xue ChenAbstract:Abstract The distributions of the heat Transfer Coefficient in a large horizontal-tube falling film evaporator under different operating conditions were investigated with numerical simulation in this paper based on the distributed parameter model (DPM). The heat Transfer Coefficient distributions along the tube row direction, tube length direction, and tube column direction were analyzed with the brine inlet spray density ranging from 0.05 kg/m s to 0.09 kg/m s and the brine inlet salinity from 30 g/kg to 50 g/kg. Results show that the heat Transfer Coefficient has higher values for the evaporating zone than the preheating zone. With the operating conditions included in this paper, the change of brine inlet salinity leads to a wider variation range of heat Transfer Coefficient along the tube length direction for the evaporating zone than the change of brine inlet spray density. The change of brine inlet spray density leads to a wider variation range of heat Transfer Coefficient along the tube row direction for the first tube pass and along the tube length direction for the preheating zone than the change of brine inlet salinity.
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space distribution of heat Transfer Coefficient in horizontal tube falling film evaporator
CIESC Journal, 2011Co-Authors: Shengqiang Shen, Luyuan Gong, Gangtao Liang, Rui Liu, Xiaohua LiuAbstract:A set of experimental facilities was set up to measure the heat Transfer Coefficient of horizontal-tube falling film evaporator.The effects of spray density on the topmost row Γ and evaporating temperature T on the overall heat Transfer Coefficient K are studied.The heat Transfer Coefficient distribution in the evaporator is presented.The results indicate that increase of spray density and evaporating temperature helps to enhance the value of K.Along the axial direction of the tube,K increases at the first 5 m and then decreases in the following 3 m,mainly caused by the condensation inside the tube.The K value decreases from the upper rows to the lower rows.In addition,increase of number of tube rows reduces the K value,especially at low spray density.
Jalil Jamali - One of the best experts on this subject based on the ideXlab platform.
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direct estimation of local convective boiling heat Transfer Coefficient in mini channel by using conjugated gradient method with adjoint equation
International Communications in Heat and Mass Transfer, 2014Co-Authors: S D Farahani, Farshad Kowsary, Jalil JamaliAbstract:Abstract The purpose of this paper was to present an inverse heat conduction method used for determining the local convective boiling heat Transfer Coefficient in mini-channel for pure water, copper nanofluid by using three different concentrations of nanoparticles: 5 mg/L, 10 mg/L and 50 mg/L. Conjugated gradient method with adjoint equation is used to solve the IHCP and estimate directly the space-variable convective heat Transfer Coefficient. Direct estimation local convective boiling heat Transfer Coefficient is a nonlinear inverse heat problem. The uncertainties in the estimated in heat Transfer Coefficient are calculated using bias and variance errors. This method is able to estimate local convective boiling heat Transfer Coefficient very well.
Balazs Illes - One of the best experts on this subject based on the ideXlab platform.
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measuring heat Transfer Coefficient in convection reflow ovens
Measurement, 2010Co-Authors: Balazs IllesAbstract:Abstract In this paper, the evaluation of a measurement method is discussed which can determine the heat Transfer Coefficient in convection reflow ovens. Nowadays the reflow ovens apply forced convection heating with nozzle-matrix blower system. In these ovens the heat Transfer Coefficients of the heater gas streams determine mainly the efficiency of heating. A method is presented which has two steps: in the first step, the heat Transfer Coefficient of the heater gas streams is studied above the assembly in function of height; in the second step, the heating efficiency of the nozzle-lines is compared as a distribution of the heat Transfer Coefficient in the oven. The heat Transfer Coefficients are calculated from the heat equation of the reflow oven. It is also presented with the distributions of the heat Transfer Coefficient that how the contamination of the nozzles affects the heating efficiency of the reflow oven.
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distribution of the heat Transfer Coefficient in convection reflow oven
Applied Thermal Engineering, 2010Co-Authors: Balazs IllesAbstract:Nowadays reflow ovens apply forced convection heating with nozzle-matrix blower system which generates numerous heater gas streams. In these types of ovens the heat Transfer Coefficients of the gas streams determine mainly the efficiency of heating. In this paper a measurement method is discussed which can determine the heat Transfer Coefficient distribution under the nozzle-matrix of a convection reflow oven. During the experiments, temperature changes have been measured and the heat Transfer Coefficient has been calculated using the heat equation of the investigated reflow oven. In the first step, the heat Transfer Coefficient of the heater gas streams has been studied under the nozzle-matrix in function of height. In the second step, the heating efficiency of the nozzle-lines has been compared and the distribution of the heat Transfer Coefficient has been calculated. The results are confirmed by a theoretical model. It is also presented that how the contamination of the nozzles affects the heating efficiency of the reflow oven. This measuring method can be useful for monitoring the operation of the reflow oven, soldering failure prediction and measuring input parameters of thermal modeling.
