Design And Working Performance Study On Film Type Fresh Air Ventilator

Fresh air ventilator is not only a good solution to the problem of indoor air quality,but also it is a highly efficient energy-saving product. In this paper a film type fresh air ventilator using plastic film as heat transfer material was designed and manufactured, in this film type fresh air ventilator flow induced vibration could be used to turbulent the laminar bottom of the fluid and thus heat transfer enhancement was achieved.Experiments as well as theory analysis were carried out to study the heat transfer behavior and pressure drop problem in the film type fresh air ventilator. The studies mainly include: The effect of flow induced vibration on heat transfer and pressure drop performance of the heat exchanger with different heat transfer material--aluminum,PVC and PET in different flux and temperature difference. The experimental systems for the performance of fresh air ventilator were set up, and the working performance of the ventilators with different film thickness was also carried out. Then, counter flow heat exchanger was designed based on the studies and empirical formula and its working performance was predicted.The results show that the film vibration induced by airflow can improve the heat transfer, compared to the traditional ones heat recovery efficiency was enhanced up 5% to 14%, and the enhancement extent is in proportion to the film vibration intensity. The amplitude of the film deformation is the major factor in improving the heat transfer. The effectiveness of the heat exchanger varies from 65% to 85% with airflow rate, the pressure drop is less than 20.0Pa, the noise is lower than 40dB, and has remarkable energy-saving effect. The vibration of the film is not only controlled by flux,film thickness and the channel, but also affected by flow field and temperature distribution.. So, there is no regularity of the heat transfer efficiency in the ventilators with different film thickness. Compared the cross-flow and the counter-flow under the same heat transfer area, the counter-flow heat exchanger has a 16%~19% of the heat transfer efficiency than the cross-flow with the airflow rate, and there is no difference in pressure drop. The results provide a theoretical basis and experimental data for the development of new type and highly efficiency fresh air ventilator.