Factors that cause uneven temperature in high and low temperature humidity test chambers

The high and low temperature humidity and heat test chamber is the main equipment of the temperature and humidity environmental test. It mainly conducts high and low temperature and humidity tests to evaluate the temperature and humidity resistance of the product, to ensure that our products can work normally under all environmental conditions. run. However, if the temperature uniformity of the high and low temperature humidity test chamber exceeds the allowable deviation range during the environmental test, the data obtained from the test is unreliable, and the data of test cannot be used as the ultimate high and low tolerance. temperature testing of materials or products. . So what are the reasons that the temperature uniformity exceeds the allowed deviation range? The following will cause everyone to conduct related research on this question.

1. Differences in the test objects in the working room of the high and low temperature humidity test chamber: if in Although test samples are placed in the working room of the high and low temperature test chamber to affect the overall internal heat convection, it will inevitably affect the internal temperature to some extent. Uniformity, that is, temperature uniformity. For example, if an LED lighting product is placed, the product itself emits light and generates heat, which becomes a thermal load, which will have a great impact on the temperature uniformity.

2. Design problems make it difficult to achieve a uniform and symmetrical structure in the design of the internal structure and space of the high humidity and heat test chamber. and low temperature, and the asymmetrical structure will inevitably lead to deviations in the uniformit the internal temperature. This level is mainly reflected in sheet metal design and sheet metal processing, such as air duct design, heat pipe placement, and fan power size. These will affect the temperature uniformity within the cabinet.

3. Due to the different structure of the inner wall of the high and low temperature humidity test chamber, the temperature of the inner wall of the test chamber will also be uneven, which will affect heat convection in the work room and cause deviations in internal temperature uniformity.

4. Due to the different heat transfer coefficients of the front, rear, left, right, upper, lower and upper sides of the workroom box wall, some have holes of threading, detection holes, test holes, etc., resulting in local heat dissipation and transfer of cheat, making the box body The temperature is not uniform, so that the radiant convection heat transfer on the box wall is not uniform, which affects the uniform temperature.

5. The sealing of the box body and the door is not strict, for example: non-customized sealing strips have seams and the door leaks, etc., which will affect the temperature uniformity of the work space.

6. If the volume of the test object is too large, or the position or placement method of the test object in the working room of the humidity test chamber to high and low temperature is not suitable, indoor air convection will be blocked, and large temperature uniformity will also occur deviation. For example, placing the product under test next to the air duct seriously affects the wind circulation, and of course the temperature uniformity will be greatly affected

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