Air distribution is an important part of indoor air conditioning. Air supply, air return and air exhaust should be provided in an air-conditioned room. Air distribution should ensure that there is no dead Angle of cyclone air supply in the room. Comfortable air conditioning should make people in the backflow area or mixed flow area to prevent the cold air from directly blowing to the human body. In order to save energy, air conditioning room should try to cut the outdoor untreated air into the air conditioning room. Therefore, it is advisable to keep positive pressure, whose pressure difference value is 5 ~ l0Pa and should not be greater than 50Pa (5mmH20). In planning, the room with high air quality requirement should be higher than the room with low air quality.
In order to ensure the hygienic requirements of indoor air, it is necessary to supply fresh air to the room continuously, and fresh air is necessary to satisfy the minimum fresh air demand of indoor personnel, as well as compensate for the exhaust air and insist on the larger value of the required air volume of indoor positive pressure. According to gb50189-2005 code of energy conservation planning for public buildings, the planned new air volume of the primary space of public buildings should be based on the existing national health code, and the new air volume of industrial buildings should be no less than 30m3/h per person.
Generally, comfortable air conditioning for civil buildings is required to stick to uniform and stable temperature and humidity in indoor human activity area. Common air supply methods can be divided into five methods according to their characteristics: side air supply, diffuser air supply, underhole plate air supply, under joint air supply, and nozzle or swirl air supply.
(1) side delivery, such as louver or slit tuyere, is one of the most commonly used airflow organization methods in the air conditioning room. It is generally presented by adhering jet flow method. Backflow is usually used in the operating area.
(2) diffuser flat feeding and side feeding are the same, operating area is always in backflow, only the air supply range and the flow of backflow are shorter than side feeding, usually in the air-conditioning room with the ceiling, the diffuser has square and round, the direction of the outlet can be 1 to 4 directions for selection.
(3) the air supply from the orifice plate is characterized by good dispersion and mixing of the jet flow, short mixing process of the jet flow, fast temperature difference and wind speed attenuation. Therefore, the temperature and speed distribution in the operating area is relatively uniform. When the air supply per unit area is large and the wind speed in the personnel's activity area is low or the regional temperature difference is severe, the orifice supply air should be selected. For example, under the tower block of the movie theater, the air supply of perforated plate is relatively high in cost, and it is mostly used for decoration of high standards.
(4) the downward delivery of seam vents is a flat jet flow, which is commonly used in surrounding areas, such as the periphery of the ceiling sceneries and the periphery of co-sharing space. It should be clarified that, due to the cost problem, during horizontal device, blade of seam is mostly perpendicular to the ground, and air flow is sent vertically down, which is easy to form a wind feeling to human body.
(5) nozzle air supply, areas in the recirculation region, supply air jet range is long, can increase the supply air temperature, air output cuts, about space larger public building and room temperature to allow shake range is greater than or equal to + 1 oc huge plant, appropriate chooses the vent air supply, wind flow air supply or ground plate type air supply, such as a large stadium, cinema.
Generally, the air return port has little influence on the indoor airflow structure, and the air return air has no inducement and directivity problems, so the type is not much, and the number of devices is less than the air supply port. In civil buildings, collected air return is more selected, and the air return port has metal grid, louver and grille of various shapes.