Experimental Study On Heat And Mass Transfer Performance Of Counterflow Evaporative Condenser

With the development of the refrigeration industry, there exists more energyconsumption inevitably. It goes without saying that the shortage of energy has become thehighlights of people’s concern. Recently, the haze occurs frequently and it has broughtmore challenges for us. Therefore, the development and application of energy-savingdevice is playing an increasingly important role in our daily life.Evaporative condenser is a highly efficient heat transfer equipment. It has theadvantages of energy-saving, water-saving and small footprint. So, it is widely used in therefrigeration industry. It is important to study the heat transfer performance of evaporativecondenser for improving the evaporative condenser cooling system. The heat transferprocess of evaporative condense is very complicated, so we should conduct a detailedstudy.To build a evaporative condenser refrigeration bench for researching evaporativecondenser performance. Through the method combined by theoretical analysis andexperimental research, we research counterflow evaporative condenser heat and masstransfer performance. The main research is the effects of air speed and spray density onheat and mass transfer. And we compared the heat and mass transfer performance ofdownstream and upstream evaporative condenser under the same experimental conditions,the conclusions are as follows.1) Air speed and spray density are the two key factors which affect evaporativecondenser. The overall heat transfer coefficient increases by the enlargement of air speedand then to flatten. It also increases by the enlargement of spray density. The air speedaffects air convective heat transfer coefficient and the spray density affects the heat transfercoefficient of water film.2) As for the evaporative condenser whose structure is given, there is an optimalamount of air and water. The best units heat transfer area air volume and quantity is299.9m3/(h·m2) and0.63kg/(h·m2) of counterflow evaporative condenser under the testconditions of the experiment, corresponding to the face velocity and optimal spray densitywas2.96m/s and0.057kg/(m·s); The best units heat transfer area air volume and quantityis307.4m3/(h·m2) and0.75kg/(h·m2) of the downstream evaporative condenser, and thecorresponding face velocity best spray density is3.28m/s and0.068kg/(m·s).3) Counterflow evaporative condenser has more advantages than downstreamevaporative condenser. Under the experimental conditions, the heat transfer coefficient ofthe former is17.2%higher than the latter. The air speed of Counterflow evaporative condensers is not too high, or it will lead to flooding phenomenon which affects heattransfer performance.4) Not only the heat transfer performance of evaporative condenser but also theperformance of the entire system during the design process. Only in this way can we let theEER to optimal values. Counterflow evaporative condenser is nearly8.2%higher thandownstream evaporative condenser.5) Evaporative condensers mainly absorb heat through evaporation latent heat with ahigh heat transfer coefficient. Comparing this condition to normal condition, the overallheat transfer coefficient of the former is about1/10of about the latter.The result of the study is beneficial for the development and design of evaporativecondenser. It also provide some reliable reference data for experimental study ofcounterflow evaporative condenser and the research of evaporative condenser heat andmass transfer performance.