| Nowadays the energy crisis is becoming serious while people pay more and more attention to indoor air quality. The air conditioning system, therefore, should create a comfortable and healthy inhabitant environment with less energy consumption. The usage of the membrane-based enthalpy exchangers can enable the air conditioning system to introduce plenty of fresh air under the condition of not increasing energy consume or even saving energy,and consequently, improve the indoor air quality. The plate enthalpy heat exchanger is a kind of total heat exchanger and has a high energy recovery efficiency and no moving components,so it is a better enthalpy heat exchanger rather than others.To overcome the situation that the former system depends on indoor and outdoor weather condition, in this work, the original system is improved. After the redesign, this system can control and simulate the typical winter and summer weather condition under any climate terms. Meanwhile, parameters like temperature, humidity, wind speed and pressure difference can be measured and controlled precisely.Three membrane-based enthalpy exchangers with different exchange materials are designed and made in this work. These materials are constructed by polyethersulfone membranes with different thickness and molecular intercepted. The heat and mass transfer performance and the air resistance property of the three membrane-based enthalpy exchangers are investigated and analyzed. The study indicates that the heat and mass transfer efficiency depends on the heat and mass transfer performance of the membrane material, the temperature and humidity of the fresh and exhaust air, the wind speed and the configuration of the exchanger. The heat exchange efficiency decreases with the rising of the wind volume, furthermore, the decreasing extent of the sensible heat exchange efficiency is smaller than that of the latent one. The indoor and outdoor air condition can influence both sensible heat exchange and latent heat exchange. The heat exchange efficiency increases with the rising of the temperature and humidity difference. However, the temperature and humidity difference's effect on sensible heat exchange efficiency is lower than that of the latent one. The thickness and pore distribution of core material can influence both sensible heat exchange and latent heat exchange. The effect of heat and mass transfer will be better if the thickness is thinner and the pore distribution is denser. There is a parabolic relationship between the resistance loss and wind volume of the heat exchanger. The resistance increases with the increase of the wind volume. At the same wind speed, the resistance loss of heat exchanger is related with its inside construction. These results provide basis for the design and application of membrane-based enthalpy heat exchanger.To enhance the heat exchange efficiency of membrane-based enthalpy exchanger, this paper imposes a high-voltage electric field in the serpentine flow field of the heat exchanger. In the same experimental conditions, the effect of external high-voltage electric field on heat transfer is analyzed by measuring the sensible heat and latent heat efficiency of heat exchanger. Additionally, on that basis, the heat exchange efficiency is tested in the circumstances of different electrode voltages, plate distance and wind speeds. The result shows that imposing a high-voltage electronic field in the serpentine flow field of heat exchanger can improve the sensible heat efficiency of heat exchanger dramatically. However, the improvement of latent heat efficiency is not obvious. The heat transfer effect of plate with 13 mm distance is better than that of plate with 7 mm distance. Furthermore, the heat transfer enhancement effect is pronounced when the wind speed is low. Arranging electronic field in membrane-based enthalpy heat exchanger is a new thought to improve the heat transfer exchanger efficiency. |
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