Design Optimization Of Surface Temperature Uniformity Of Air Cooler

People need more food storage along with the economic development and the improvement of quality of life. Air cooler was known as common refrigerator cooling equipment, and its thermal performance is an important factor to storage building and the food quality, so the study that how to improve the performance of air cooler will be very significance. Guiding ideology of research on air cooler was mainly by improving the air-side pressure drop to improved heat transfer performance that including of changing the number of tube rows, increasing the fin number, change fin structure, increase wind speed, which to a certain extent improved the cooler, but there is a widespread problem at the cost of consumption pump. With the appearance of new and enhanced heat transfer theory, based on the premise of not increasing pump, we changed the flow, refrigerant circulation and the displacement of fan and finned tubes to improve the cooling, thereby air cooler would be increased the heat transfer surface temperature uniformity, finally, air cooler performance was improved. The paper made theoretical and experimental research of following aspects, for convenience of optimizing design of heat exchanger flow arrangement, and further improving the performance of fin-and-tube heat exchanger.1. SimulationThe paper applied COMSOL Multiphysics simulation platform for air coolers in the tubes of two-phase flow and heat transfer simulation. By establishing a reasonable model of non-isothermal flow and two-phase flow model coupled to u-type, Z-type, single-double type and double-single type in 4 kinds of process layout simulation calculation of the heat transfer performance of air cooler. Simulation results are as follows 1) Under the same size and wind speed of heat exchanger, as well as the same mass flow rate, "u" type counter and "z" type flow arrangements made good performance. Under normal circumstances, if you only consider economic production facility conditions, it can be used as the recommended layout. In the condition of same size and refrigerant mass flow rate, double-single flow arrangement is better than single-double flow arrangement. 2) That we choose the appropriate division point such as "double-single" arrangement was the most uniform temperature field on the surface of the heat exchanger, which proposing resettlement process based on "principle of constant heat flux density ", namely heat transfer performance is probably the best. There was big change of heat transfer coefficients between two-phase and single-phase in the heat exchanger, allocate single and two-phase heat transfer area, make full use of different potential of the local heat transfer coefficient, enhanced heat transfer coefficient allows to achieve the best results.2. Experimental studyAccording to the conclusions of the simulation, we choose the best flow arrangement of dual-single to design of a new type finned-tube heat exchanger air cooler. The test platform system was configured with turbine liquid pump. With combined correlation with temperature difference field in the synergy theory for heat convection and the field synergy factor in, as well as the synergistic factors and the correlation between heat exchangers. Then the experimental results and simulation results are compared. Experimental studies of the analysis are as follows:1)In constant of displacement of fan and evaporation tube, we made experiment analysis on different filling volume of "double- single " flow arrangement, the results showed: "double-single " flow arrangement meet the best times liquid magnification is 1.2. Under same condition, heat exchanger of temperature difference field performance the best, heat exchanger of uniformity factors reached maximum value 0.9, and compressor energy at least for 936 Wh. Below that magnification filling quantity, synergistic factors of temperature field of heat exchanger increases as the amount of liquid, and continue to increase the amount of liquid, synergistic factors remain unchanged.2) We made the filling volume instantly, adjust the distance between the fan and the pipe, Experimental results showed: there is maximum synergistic factors of temperature field at best distance 33 cm with fan moving, while minimum energy consumption of the compressor. When the distance is less, the compressor energy consumption increased with the displacement, when the value is exceeded, the energy consumption of the compressor with displacement increases. Study also found that when the displacement at optimal filling amount, air cooler in the best position can reduce energy consumption 8.6%. 3) Simulation of optimal refrigerant is less than 20% in experiments.