Analysis And Experiment On Heat And Mass Transfer Characteristics Of Tube-in-tube Evaporative Condenser

At present in the common use condenser in the refrigerant devices, there are three types, they are air cooling condenser, water cooling condenser and evaporative condenser, considering the heat transfer performance of air cooling condenser is low, the cooling water of water cooling condenser needs to be cooled in cooling tower, not only the setting is large, this takes great mount water but also takes more energy. A new type condenser—tube-in-tube evaporative condenser is proposed, it is added a inner tube in the heat exchange tube on the basis of the evaporative condenser, it results the refrigerant can exchange heat in the inner tube, but also it augment the heat exchange area. The circulative cooling water is sprayed onto the wall of outer tubes, water film contacts to air, the energy mainly carried by the water evaporation, heat transfer carry mainly through latent heat form.The configuration and theoretical analysis of the evaporative condenser is carried, in the same condition the analysis between evaporative condenser and common evaporative condenser is done. The results show that in the same condition the average heat flux density of evaporative condenser is one point eight times to the heat flux of common evaporative condenser, and its heat transfer ability is better.There are many studies on the inner part of condenser, heat tubes about heat transfer in the world; there are many experimental relating equations. Little studies is taken to the evaporative condensation on the skin of heat transfer tubes, water is sprayed on skin of heat transfer tubes. The heat transfer ability is researched to the condition that is water is sprayed on the heating tubes by experiment, this paper mainly deals with the effects of the different heat flux density, circulative water flux, air flux and wet ball temperature, the result for the project practice is induced.The heat flux density changes from 2.6kW/m to 8.87kW/m in the experiment, the amount of sending water changes from 0.1m3/h to 0.23m3/h, the amount of sending air ranges from 0.738m3/h to 1.5438m3/h, wet bulb temperature changes along with the circumstance. The experiment shows that in the experiment range the heat transfer coefficient of the heating tubes increases when the water flux increases, when the water fluxes and the air fluxes are invariable, the heat transfer coefficient increases in the first and then declines; the heat transfer coefficient is invariable. When the air fluxes reaches about 3.288m3/(h·kW), changing the air fluxes, the heat transfer coefficient don't change obviously. Wet bulb temperature is very important to the setting performance, when the wet bulb increases, the heat flux density declines, the temperature of tubes wall increases. The experiment shows that the least sending water flux is about 0.46 m3/(h·kW),and the sending air flux is about 3.288m3/(h·kW).