The air distribution form and ventilation requirement of the outlet of high efficiency air filter in clean room are the important guarantee measures to realize the purification of environment. Generally, there are two kinds of air distribution: non-laminar flow and laminar flow. The dilution of dust generated in the workshop by air purified by highly efficient filters is called non-laminar flow (turbulent flow). The air flow purified by high efficiency air filter is used as carrier to discharge dust, which is called laminar flow mode. There are two types of laminar flow: vertical laminar flow and horizontal laminar flow. From the roof direction through the air filter into the clean air through the horizon discharge called vertical laminar flow, from the side direction through the high efficiency filter into the clean air, from the opposite side wall discharge called horizontal laminar flow. The cleanliness of turbulent flow mode varies with the change of total air volume and ventilation times of high efficiency air filter, but when the cleanliness requirement is 10000, the ventilation times are in the range of 25-35 times/hour; when the cleanliness requirement is 100000, the ventilation times are in the range of 15-25 times/hour; and when the cleanliness requirement is 300000, the ventilation times are in the range of 15-25 times/hour. In the range of 12-18 times per hour. Laminar flow usually specifies gas flow rates of 0.25-0.5M/S.
For specific purposes, the indoor air filters result in a certain air flow state and distribution, which is usually called air distribution. Generally speaking, the air from the air supply outlet into the room first forms the jet air flow, which flows to the room return air outlet is the return air flow, and the swirl air flow in the local space of the room. In order to obtain a low and uniform dust concentration in the working area, the basic principles of the air distribution form and ventilation requirements of the outlet of the high-efficiency air filter in the clean room are as follows: to reduce the eddy current to a great extent; to cover the working area as soon as possible through the short flow of the air injected by the air filter, in the hope that the direction of the air flow of the high-efficiency air filter can work with dust. The settling direction is the same, so that the return airflow can effectively discharge indoor dust outdoors. It can be seen that the clean workshop is completely different from the general air-conditioning workshop. To determine the air distribution form and ventilation requirement of the outlet of the high efficiency air filter in the clean room, the air flow of the air filter should be calculated according to the heat balance, air flow balance and purification requirement, and the * large value should be taken. For details, please refer to [http://www.gd-klc.com/].
1. Advantages of turbulence:
1) High efficiency air filter and simple air treatment;
2) The cost of equipment investment is low;
3) It is easier to expand the scale of production.
4) The cleanliness of the air filter can be maintained when combined with the purification table.
2. Disadvantages of turbulence mode:
1) Indoor cleanliness is susceptible to the influence of workers.
2) Eddy current is easy to produce and polluted particles may circulate indoors.
3) The air filter has low ventilation frequency, so it takes a long time to enter the normal operation and increases the power cost.
3. Advantages of vertical laminar flow:
1) Not affected by the working status of indoor workers, it can maintain a high cleanliness.
2) High ventilation frequency, almost in operation at the same time can achieve a stable state;
3) There is very little dust accumulation or re-floating. The dust generated in the room is removed by airflow and quickly recovers from the polluted state to the clean state.
4. Disadvantages of vertical laminar flow:
1) The trouble of installing the end-air filter and the switch board will easily lead to the damage of the sealant pad of the high-efficiency air filter.
2) The cost of equipment investment is higher.
3) It is difficult to expand the scale of production.
5. Advantages of horizontal laminar flow mode:
1) Because of eddy current, dead angle and other reasons, the chance of dust accumulation or re-floating is relatively reduced.
2) High frequency of air exchange, so the self-purification time is short.
3) The indoor cleanliness is not disturbed by the number of workers and their working conditions.
4) The buffer system of cloakroom, work clothes cleaning room, dressing room and air shower room need to be improved.
6. Disadvantages of horizontal laminar flow:
1) High cleanliness can be maintained near the suction surface, but the cleanliness decreases when it approaches the suction surface.
2) It is difficult to expand the scale of production;
3) The cost of equipment investment is higher.
4) The buffer system of cloakroom, work clothes cleaning room, dressing room and air shower room need to be improved.
From the above analysis, it can be seen that if all the purification systems in the operating room are designed as the above laminar flow mode, the cost of equipment and additional engineering will be higher. Therefore, in this case, the local laminar flow purification mode can be considered. In this way, it is not necessary to have such a high level of environmental cleanliness for a large area of a clean workshop, and in fact, it is very difficult for a clean workshop to achieve 100 levels of total cleanliness.