Gas-permeable membrane ventilation system SEPERNA®

A good air environment cannot be created by temperature and humidity control alone. It is necessary to purify dirty air. To do this, ventilation with outside air must be performed. Of course, ventilation is also essential for expelling viruses. However, this ventilation puts the most heat load on the building. The air that has been cooled/warmed is returned to its original temperature. This has been a long-standing dilemma for thermal environment technology. Conventional "normal ventilation" takes outside air directly into the room, so it is a burden to that extent. Therefore, if "total heat exchange ventilation" is performed, in which the exhausted indoor air and the intake outside air are brought into contact with each other through pipes or the like to exchange heat, the heat burden is reduced to about half. However, the absolute burden of ventilation itself is large, so in order to further reduce this burden, we have begun developing technology to turn the air into fresh air using methods other than ventilation. We focused on the gas permeable membrane ventilation system.

One method of purifying the air without ventilation is air purification using filters, but this can only remove large particles such as dust and pollen. Also, ventilation was the only method that could reduce carbon dioxide concentration. Therefore, gas exchange using membranes was developed to achieve both. When there is a difference in CO2 concentration inside and outside a membrane with micropores of 10 nm or less, CO2 moves from the higher concentration to the lower concentration. This property is used to move indoor CO2 to the outdoor air. At the same time, O2 from the outdoor air moves to the indoor air. In this way, gas exchange of CO2 and O2 takes place between the indoors and outdoors.
The membrane of this CO2 membrane separator is shaped like a tube with a diameter of about 2 mm, and the system passes indoor air through it and outside air on the outside. Approximately 800 tubes are collected into one unit, and 96 of these are lined up to form one box. Gas exchange is carried out by passing indoor air through the unit tube and outside air through the box.

The most efficient way to use this system is to use the excess air in the building instead of outside air. In this case, demonstration experiments have shown that the energy consumption is 50% lower than normal ventilation and 20% lower than total heat exchangers. With current technology, one CO2 membrane separator is calculated to be able to process the CO2 emitted by 20 people, which is not yet enough to process the entire ventilation volume of a building, so it is used in conjunction with normal ventilation and total heat exchangers. However, this capacity will continue to evolve.
In recent years, outdoor air is not necessarily clean. Depending on the season, it may contain harmful substances such as pollen and PM2.5, so unless a high-performance filter is used, there are cases where ventilation itself must be restricted. One solution to this problem is this membrane separation device. Currently, there are studies being conducted to add a function that can remove aerosols using a membrane separation device, which is recommended to be discharged through ventilation.