Comparison and comparison of two expressions of th

Comparison and analysis of two expression methods of temperature deviation and temperature uniformity

1) although the temperature uniformity index can be used to express the good or bad temperature uniformity of the working space in the box, because the method of multiple average values is used in the calculation, the temperature fluctuation factor of each point is basically removed. However, for the temperature performance index of the test equipment, it is not enough to only mark the temperature uniformity. There must also be temperature fluctuation index, that is, the change of temperature at each point with time, in order to comprehensively describe the change of temperature field in the box, especially when the temperature fluctuation is large

2) the temperature deviation not only reflects the position error of the temperature at each point in the working space, but also includes the error of the temperature at each point changing with time, that is, the temperature fluctuation. Therefore, the temperature deviation can better explain the temperature uniformity in the box. Generally, there is no need to test the temperature uniformity and temperature fluctuation of the box. Only when some test equipment has special requirements for temperature fluctuation, such as damp heat box, can the temperature fluctuation be marked. Because the cement is compressed in the damp hot box, the hardness value measured by the broken judgment record is broken. If the degree fluctuation of pulling (or pressing) to a certain experimental force is more than ± 0.5 ℃, it will bring greater humidity fluctuation, increase the humidity error, and thus exceed the allowable humidity deviation

gb/t5170.2-1996, in the verification method of temperature test equipment, only the verification temperature deviation is specified for the temperature performance index, while the temperature uniformity is not specified to be verified. Only the verification method of temperature fluctuation and temperature uniformity is indicated in Appendix B. such a regulation is very correct

3) the temperature uniformity index, because it represents the difference between the average temperature value of each point and the average temperature value of the center point, has a positive and negative sign. Only the temperature uniformity of the national standard, because it is not compared with the center point or with the nominal temperature controller and software, there is no positive and negative sign, so there is no clear and accurate representation method of temperature deviation

4) at present, some domestic product standards for environmental testing equipment still require three indicators: temperature fluctuation, temperature uniformity and temperature deviation to improve the activity of transmission medium, which is obviously unnecessary. It is suggested to adopt temperature deviation index when revising these standards, and it is very comprehensive to add at most one temperature fluctuation index