Experimental Study And Numerical Simulation Of Fin-Tube Heat Exchangers Under The Different Inlet Air Conditions

The fin-tube heat exchanger is widely used in power, chemical, petrochemical, refrigeration engineering. Currently, it is one of the most used heat exchanger. To analyse and study the characteristics of fin-tube heat exchanger not only has important practical significance, but also is an important role in promoting the current energy conservation.The parameters, which can influence the performance of fin-tube heat exchanger, include fin pitch, row number, fin thickness, tube diameter, fin material, media temperature and flow rate inside the tube, dry bulb and wet bulb temperature, air velocity and installation inclination. However, it has hardly reported in the field study that the impact of installation inclination and inlet condition on the performance of heat transfer and pressure drop, most of the studies are focused on the structural parameters of fin-tube heat exchanger.In this study, the heat exchanger is tested on the test rig with using of enthalpy difference method. To ensure precision of test results, the accuracy of the sensors and the stability of the experimental conditions should be validated. And they are done when the test rig is setting.The object of this study is to evaluate the performance of heat transfer and pressure drop of heat exchanger under the different inlet conditions. Based on experiment, the effects of the different inclination angles and the effects of free and restricted air intaking conditions are included. To validate the test result, a CFD simulation model is setup to analyse the performance of the heat exchanger. The following contents are included in this study:1. Experimental studies are carried out to analyse the performance of heat transfer and pressure drop under free air inlet condition with six inclination angles(-60°,-45°,-30°,30°,45°,60°);2. Experimental studies are carried out to analyse the influence on heat transfer and pressure drop under free and restricted air inlet conditions with six inclination angles listed above;3. Experimental studies are carried out to analyse airside performance of heat transfer and pressure drop with the same inclination angle under restricted air inlet condition. 4. Numerical simulation of airside heat transfer performance.The simulation model based on Fluent software is setup by simplified the actual model, and the heat transfer coefficient under free and restricted air inlet conditions are simulated. Several inclination angles are selected to compare the results with the experimental results to investigate the reliability.Some conclusions are obtained after the studies listed above:1. Under free air inlet condition, the heat transfer coefficient of inclination angleθ=±45°is larger than that of others. The heat transfer coefficient of positive inclination angle is better than that of negative inclination angle. The results of simulation show that the outlet air average temperature whenθ=±45°is lower than other inclination angles;2. Pressure drop increases with the increasing of the absolute value of the inclination angleθ;3. When the inclination angle is positive, the heat transfer under free air inlet condition is better than that under restricted air inlet condition. The result is opposite when the inclination angle is negative. The results of simulation show that the outlet air average temperature under restricted air inlet condition is lower than that under free air inlet condition;4. The existence of duct has no effect on pressure drop; 5. When the inclination angle is the same, inlet air angle has no effect on heat transfer and pressure drop. The simulation shows the same result;6. Inlet air angle has less effect on the pressure drop of the heat exchanger.