Thermal Experimental And Numerical Analysis Of Two Tube Fin Type Evaporator

Elliptical finned tube evaporator, a kind of evaporator that there is no mass production and application at present, has great market potential. Compared to circular finned tube evaporator, it has obvious advantages as below:Firstly, the heat exchange effect is improved;Secondly, the external flow characteristics of elliptical tube is better;Thirdly, the structure of evaporator is compact.However, the current research is usually theoretical analysis or numerical simulation analysis, they fail to reflect the advantages and disadvantages between elliptical finned tube evaporator and circular finned tube evaporator directly. In this paper, these two kinds of evaporators are taken as experimental subjects.Regarding to the heat exchange effect outside of tubes, the paper focuses on the research and presentation of excellent heat transfer performance and resistance loss of elliptical finned tube evaporator. The judgement for better choice would be given by comparing and analysing the heat transfer performance outside the tubes and Resistance loss between them.In the first part, this paper introduces the experimental device, procedures, methods and test equipment. The experiment content is to test the circular air volume,total pressure, and the wet and dry bulb temperature of air inlet and outlet of two types of evaporators in different conditions. The experiment data would reflect the heat transfer performance outside of tubes and the size of wind resistance. Through the experiment, the comparing analysis about the properties of two types of evaporators would be more convincing. In one side, it can reflect the performance characteristic of two kinds of evaporators by the real test. In another side, it can provide verification and enough date sample for the latter numerical simulation calculation.In the second part, the paper introduces the difference between the two kinds of evaporators in the following aspects: the establishment of the numerical model and boundaryconditions, the choice of the solves. Using turbulence model and compositional models to set the air inlet working conditions and obtain the cooling capacity, then comparing with the experiment data, to check the correctness of the numerical model and analysis the error.From thermal properties of two tube type evaporator, the refrigerant in the tube heat transfer coefficient has little difference.Under different inlet air temperature,the elliptical tube fin evaporator is smaller than that of the circular tube fin evaporator 5.90%- 8.16%, and The equivalent heat transfer coefficient and heat transfer coefficient of the outer surface of the elliptical tube evaporator is much larger than that of circular tube type, and the average ratio of the tube is 75.70% and 57.15%. It is concluded that the elliptical tube evaporator has more excellent thermal performance.In the third part, the paper through the comparing analysis of the experiment data and numerical simulation results, to confirm the correctness of the numerical simulation model by the comparison of the cooling capacity model. By analyzing the full pressure, the cooling capacity of the kinds of tubes, draws a conclusion that the elliptical finned tube evaporator’s Resistance loss is less than the circular finned tube evaporator, and could reduce draught fan pressure head. Under certain interval of cooling capacity, elliptical finned tube evaporator’s consumption of copper and aluminum is less.In the last part, an elliptical finned tube evaporator is designed base on the range of engineering applications. Its cooling capacity is consistent with that of the circular finned tube evaporator produced by current manufacturers. By comparing analysis of properties, get the result that in a certain range of cooling capacity, the equivalent heat transfer coefficient and heat transfer coefficient of the outer surface of the finned tube evaporator is much larger than that of the tube type, and the average ratio of the tube is 99.84% and 54.05%.And elliptical finned tube evaporator’s Resistance loss is less and can reduce the fan pressure; and under a certain interval of cooling capacity, the consumption of copper and aluminum is less.Concerning the evaporator, elliptical finned tube evaporator’s copper consumption amount is 88.0kg, aluminum consumption amount is 71.9kg; while the circular finned tube evaporator’s copper consumption amount is 117.9kg, aluminum consumption amount is121 kg.