Heat Transfer And Pressure Drop Characteristics Of A Tube Bundle Immersed In Bubbly Flow

At present in the cooling mode of condenser in refrigeration devices, the cooling water needs to be cooled in cooling tower. Not only this takes more energy but also the settings are so large. A new-style foaming evaporation for cooling equipment and the tube bundle immersed in bubbly flow is designed in this paper. A porous sintered sand plate instead of usually used sieve plate, generate more serried and finer bubbles. As compared to the accustomed spraying heat transfer equipment, the heat transfer tube bundle in the designed equipment is placed in the bubbles. The tubes wall contacts the cooling water and air bubbles by turns, heat is removed by the water evaporation, heat transfer carry mainly through latent heat form. As there are so little attention and studies on the processor foaming evaporation cooling about heat transfer in the world at present. The evaporative heat transfer Characteristics influenced by the air flow rate through the porous sintered sand plate and the heat flux density in the surface of heating tube bundle and the form of tube bundle arranged is studied in this paper. The heat transfer and resistance experimental relating equation on these experimental conditions are summarized. The three porous sintered sand plate effective foaming acreage respectively were 0.0413 m2,0.03192m2,0.0273m2. The superficial air velocity ranges from 1.7 cm/s to 7.1 cm/s; the heat flux changes from 1kW/m2 to 19kW/m2.The results show that the heat transfer coefficient of the heating tube bundle surface increases when the superficial air velocity or the heat flux density increases. The heat transfer coefficient of the parallel heating tube bundle is larger than that of the staggered heating tube bundle in the same conditions. The experimental data are used to develop two heat transfer correlations of staggered and parallel heating tube bundle and the errors are separately 18% and 13%. The pressure drop of air passing through the sand plates and the bubble layer is also examined, which is mainly influenced by the superficial air velocity. When the superficial air velocity increases, the plate resistance increases. The pressure drop of air passing through the bubble layer is mainly influenced not only by the superficial air velocity but also by the height of bubble layer. The experimental data are used to develop a correlation of the total resistance as follows: P = △P_D +△P_L=7. 46×10~5 V~1.687+2.0×10~5V~0.8H~0.3...