The national standard of the constant temperature and humidity test box has a clear stipulation. In a cubic test space, the temperature uniformity in the box should be less than or equal to ±2°C. However, when we test products have some characteristics, it will affect the temperature uniformity of the room. So, what are the factors affecting the uniformity of the constant temperature and humidity test chamber?
The test products that affect the uniformity of the constant temperature and humidity test chamber mainly show the box seal, heat load, heat radiation characteristics, heat transfer, sample placement, internal structure and so on.
1. Sealing: The sealing of cabinets and doors is not strict. For example, sealing strips are not custom-made with seams, and the door leaks, which affects the temperature uniformity of the working space.
2. Thermal load: If the test chamber is sufficiently exposed to the test sample that can affect the internal thermal convection, it will inevitably affect the uniformity of the internal temperature to a certain extent. For example, if the LED lighting product is placed, the product itself has a luminescent heat and becomes a heat. Load, then there is a great influence on the temperature uniformity. ,
3, heat radiation: design problems lead to inspection box in the internal structure, space design is difficult to achieve a uniform symmetrical structure, and asymmetric structure will inevitably lead to internal temperature uniformity deviation, this level is mainly reflected in the sheet metal design And sheet metal processing, such as: the design of the air duct, the location of the heat pipe, the size of the fan power and other reasons.
4. Heat transfer: Because the heat transfer coefficient of the upper and lower sides of the chamber is different from that of the upper and lower sides of the box, some of them have holes, detection holes, test holes, etc., which lead to local heat dissipation, heat transfer, and uneven temperature of the box. Therefore, the wall convection heat transfer is also non-uniform, affecting the temperature uniformity.
5. Rationality of sample selection and placement: if the test object is too large, or the test object is placed in a location or manner in the working chamber of the constant temperature and humidity testing machine, the convection in the air will be blocked and large The deviation of the temperature uniformity. For example, putting the test product on the side of a wind tunnel seriously affects the circulation of the wind, and of course, the temperature uniformity will be greatly affected.
6. Due to the different inner wall structure, the temperature of the inner wall of the test chamber will also be uneven, which will affect the thermal convection inside the work chamber and cause deviation of the internal temperature uniformity.
The test products that affect the uniformity of the constant temperature and humidity test chamber mainly show the box seal, heat load, heat radiation characteristics, heat transfer, sample placement, internal structure and so on.
1. Sealing: The sealing of cabinets and doors is not strict. For example, sealing strips are not custom-made with seams, and the door leaks, which affects the temperature uniformity of the working space.
2. Thermal load: If the test chamber is sufficiently exposed to the test sample that can affect the internal thermal convection, it will inevitably affect the uniformity of the internal temperature to a certain extent. For example, if the LED lighting product is placed, the product itself has a luminescent heat and becomes a heat. Load, then there is a great influence on the temperature uniformity. ,
3, heat radiation: design problems lead to inspection box in the internal structure, space design is difficult to achieve a uniform symmetrical structure, and asymmetric structure will inevitably lead to internal temperature uniformity deviation, this level is mainly reflected in the sheet metal design And sheet metal processing, such as: the design of the air duct, the location of the heat pipe, the size of the fan power and other reasons.
4. Heat transfer: Because the heat transfer coefficient of the upper and lower sides of the chamber is different from that of the upper and lower sides of the box, some of them have holes, detection holes, test holes, etc., which lead to local heat dissipation, heat transfer, and uneven temperature of the box. Therefore, the wall convection heat transfer is also non-uniform, affecting the temperature uniformity.
5. Rationality of sample selection and placement: if the test object is too large, or the test object is placed in a location or manner in the working chamber of the constant temperature and humidity testing machine, the convection in the air will be blocked and large The deviation of the temperature uniformity. For example, putting the test product on the side of a wind tunnel seriously affects the circulation of the wind, and of course, the temperature uniformity will be greatly affected.
6. Due to the different inner wall structure, the temperature of the inner wall of the test chamber will also be uneven, which will affect the thermal convection inside the work chamber and cause deviation of the internal temperature uniformity.
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