Performance Investigation Of Horizontal Oval-Tube Under Water Film

Evaporative cooling technology is to refrigerate through water evaporation, which is envi-ronment friendly, effective, and low cost. With its wide applications, power energy consumption can be largely reduced, especially meaningful during the power peak. Then, the emission of greenhouse gases and CFC can be decreased. Closed-wet cooling tower is one kind of indirect contact cooling tower, which dates back to industrial evaporative cooler. It mainly applies to oc-casions of that cleanliness rate is high and of that water temperature needs restrict control, but is not usually used in occasions with common open cooling tower.Because of the importance of environmental protection and energy saving, the development of electronic, power plant, foundry, food, chemical, construction industry,market for evaporative cooler/closed cooling tower demand growing very rapidly. Studying of evaporative cooling pro-cess of heat and mass exchange maechanism in-depth can provide theoretical basis for the equip-ment selection and improving the thermodynamics of evaporative cooling process. It also makes an important significance in energy-saving,reducing environmental pollution, improving the working environment and improving labor efficiency.The heat transfer performance of closed cooling tower is affected by the structure of heat ex-changer, environment, air flow volume and spray water and other factors. Heat exchanger coils is the key component of the closed cooling tower, which directly affects the heat transfer perfor-mance. How the water film gets influenced by the tube type mainly lies in the heat transfer area, the patterns of water film flow and water film distribution, etc. Therefore, tube optimization can effectively improve the heat transfer performance. Large numbers of results show that flow pat-terns, update rate and distribution of liquid film will play an important role on heat transfer per-formance. This research project aims to research on heat transfer performance of oval tube with water film. Through the numerical simulation and experimental of oval-tube in the closed cooling tower can get the following conclusions:(1) Simulate the air velocity, temperature and relative humidity of the experimental unit in actual operating conditions of the test-bed. Air velocity distribution figure can provide a reference for the experimental data below. It can be seen that the temperature near the coil is higher than elsewhere in the temperature distribution figure, because it transfer heat intensely. The relative humidity distribution figure indicates that the relative humidity relative humidity rise with the air flow.(2) Experiments results show that heat transfer coefficient of oval tube is affected by flow rate of cooling medium, its external spray density and the rate of length to width of the oval tube. And the mass transfer coefficient is decided by air flow volume entering the cooling tower. The heat transfer coefficient increases with the flow velocity initially, but decreases with the further increase of flow rate. the coefficient increases with the spray density until the water film totally is totally covered on the tube. The mass transfer coefficient increases with the air volume entering the cooling tower. However, over-large volume can lead to floating water, which is sabotage to the mass transfer. Under the same other conditions, the total heat transfer coefficient achieves the highest value with circle tube when the cross girth are the same.