| Air conditioning and ventilation system has been widely used in modern architecture. In ventilation and air conditioning system, local resistance generally accounted for more than 40% of the total resistance loss. To improve energy efficiency, energy conservation and emissions reduction, it is important to optimize the local components existing in air conditioning and ventilation system.In ventilation and air conditioning system, the 90 ° pipe bend, three way pipe and variable diameter pipe is the main local resistance component. This study discuss the ventilation resistance reduction rectification theory and design method of 90 °pipe bend in the air conditioning system based on the existing research.First of all, the cause of ventilation and air conditioning system resistance loss and factors has been studied through theoretical analysis. Measured the experimental model of velocity field and pressure loss by full size experiments, and RSM model(Reynolds stress) was verified in predicting the accuracy of the pipe resistance losses.Secondly, predicted and analyzed the impact of different working condition and airflow organization to the local resistance of pipe bend through the numerical simulation. Optimize different size of pipe bends with different ways through software, also predicted the results of drag reduction with numerical simulation to those optimization programs. According to the result of prediction, this study gives several optimization schemes with better drag reduction effect, and fitting out the corresponding pipe bend arc formula.Finally, the drag reduction of several optimization pipe bend are verified by full size experiments. In addition, analyzed and demonstrated the feasibility and applicability of optimization pipe bend in design, manufacture and installation in practical engineering. Results show that the optimized pipe bend can reduce the local resistance in the air conditioning and ventilation pipe(the reduce range 7% to15%), has preferably practical value. |
PDF Full Text Request