Condensation Heat Transfer Of Marangoni In Plate Heat Exchanger And Model Optimization Design

Plate heat exchanger(PHE) has the incomparable advantage and the application of plate heat exchanger have been increasing. Due to the condition of low Reynolds number appearing turbulence state in plate heat exchanger, the heat transfer coefficient is high. Due to the difference of surface tension of condensation liquid, the condensation of mixed vapor of positive system can appear the Marangoni effect and form dropwise condensation or Pseudo-dropwise condensation.The purpose of this paper was to experimentally study average heat transfer coefficient and pressure drop in pleat heat exchanger for Marangoni condensation of ethanol–water vapor mixtures. The test rig of Marangoni condensation in plate heat exchanger with high air tightness could run in positive and negative pressure conditions. To avoid uneven distribution, plate heat exchanger was composed of three chevron-type plates. Hot and cold fluids were vertical flow.The experiment was carried out under different mass concentration alcohol of gas phase(0%, 1%, 10%, 50%), different pressure(70kPa, 80 kPa, 90kPa) and different mix vapor speed(u=15m/s, u=25m/s), the focus study was the average heat transfer coefficient and pressure drop with the changing inlet temperature of cooling water. The heat transfer model and pressure drop model were also studied.The results showed that, the average heat exchange coefficient increased with the increasing of inlet temperature of cooling water, and pressure drop was decreased. The average heat exchange coefficient increased at alcohol concentration 1%.It was similar to pure water vapor at concentration 10%, but the average heat transfer coefficient at 50% was lower than other concentrations. At 90 kPa and low alcohol concentration 1%, average heat transfer coefficient increased obviously, increased by about 6%.The pressure drop increased with the increasing of alcohol concentration, and the total pressure drop at high concentration 50% increased to 2 times. The influence of the vapor pressure on the average heat transfer coefficient and the pressure drop was obviously. The average heat transfer coefficient at 90 kPa was the largest, the 80 kPa followed, the 70 kPa was the smallest, while the pressure drop was opposite. Although the average heat transfer coefficient had obviously up and down trend, the value at 15m/s was close to 25m/s. The flow velocity had little effect on the average heat transfer coefficient, but it had a great impact on the pressure drop. The total pressure drop at 25m/s was almost double that of 15m/s. On the basis of experimental data, heat transfer model of mixed vapor condensation in plate heat exchanger was studied by introducing Jockob criterion that signified film sensible heat and latent heat, the experimental value and calculated value contrast error was between-35% to +35%. The frictional pressure drop was calculated by Lockhart-Martinelli model. The frictional pressure drop accounted for the proportion of the total pressure largely. Therefore the total pressure drop calculated though the frictional pressure by a constant correction. The results showed that experimental values and the calculated value of error comparison was between 20% to-20%.The study of condensation heat Transfer of marangoni in plate heat exchanger and model optimization design provided a certain theoretical and experimental foundation for the mixture vapor condensation in plate heat exchanger. This will further promote the use of low temperature energy and energy conservation and emission reduction. Moreover, the above conclusions have important reference value for selection of conditions and the design of plate heat exchanger.