How to Improve Temperature Control and Optimize Performance of High and Low Temperature Test Chamber

In addition to components such as compressors, pressure accumulators, condensers, and dryers, the refrigeration system of the high and low temperature test chamber also has several parts such as capillary tubes, solenoid valves, evaporators, and pressure protection. The combination of mechanical refrigeration and liquid nitrogen refrigeration is used. It consists of two parts and each part is a relatively independent refrigeration system. Since the requirements for the test temperature are low, the cascade refrigeration method is often used.

The high and low temperature test chamber is equipped with two sets of refrigeration compressors. If the temperature of the test chamber equipment is unstable, it can be checked by a method. The temperature instability is usually caused by the lack of refrigerant. Everyone can see the discharge pressure and suction pressure of the compressor. If the unit has a low pressure value and the suction is being drawn at pressure, it is a refrigerant volume issue.

In addition, the discharge pipe and suction pipe of the test chamber compressor should also be checked. If the temperature of the exhaust pipe is not high and the temperature of the suction pipe is not low, it is necessary to add refrigerant. If the temperature of the equipment in the test chamber is unstable, check whether the refrigeration compressor can be started during the operation of the test chamber. If it can be started and used normally, it means that the main power supply is stable, and then check whether there is any problem in the electrical aspect. If the electrical operation is normal, you should check the reason from the refrigeration system.

Refrigeration is the basic function setting in the high and low temperature test chamber. How does its function work?
Liquid nitrogen refrigeration is to inject liquid nitrogen into the low temperature test chamber, and use its evaporation process to take away heat, so as to achieve the effect of reducing the temperature of the test chamber.

Liquid nitrogen changes from liquid to gas during this process, because its heat of vaporization is very large in liquid state, so liquid nitrogen is easy to volatilize in the air, and it also has a strong cooling effect. In a low-temperature test chamber that uses liquid nitrogen refrigeration, a liquid nitrogen storage tank is usually set up to transport liquid nitrogen to the refrigerator in the test chamber, and then the refrigerator injects liquid nitrogen into the test chamber to achieve constant temperature. .

Compared with other refrigeration methods, liquid nitrogen refrigeration has the advantages of fast refrigeration speed, high temperature control accuracy and wide temperature range. Moreover, liquid nitrogen refrigeration will not produce ozone-depleting substances, will not pollute the environment, and will not have any impact on the tested samples.

However, liquid nitrogen refrigeration also has some potential risks and precautions. First of all, liquid nitrogen is a very dangerous substance, so you must strictly follow the relevant regulations when storing and using liquid nitrogen. At the same time, the temperature of liquid nitrogen is very low, which may cause harm to the human body, so you must pay attention to protecting yourself when using it. In addition, the consumption of liquid nitrogen is also an issue that needs to be considered. The price of liquid nitrogen is higher, and the higher the frequency of use, the higher the cost.

In general, liquid nitrogen refrigeration is one of the commonly used refrigeration methods for cryogenic test chambers. It has the advantages of fast refrigeration speed, high temperature accuracy, and wide temperature range. However, the use of liquid nitrogen refrigeration also requires attention to some risks and precautions. In addition to the necessary safety and environmental awareness, attention must also be paid to controlling the consumption of liquid nitrogen to control costs.

In the high and low temperature test chamber, the high temperature ambient temperature is affected by the power of the circuit, the change of the position of the aging plate, the change of the oven network speed and other factors, which lead to the change of the temperature field in the chamber. The drastic change of the temperature field in the chamber will affect the normal aging test of the product and form overstress, which will lead to circuit failure in severe cases. The temperature factors affecting the equipment were tested, monitored and analyzed to find out the main reasons and rules affecting the temperature, and better heat dissipation measures were taken to prevent the aging circuit from over-temperature failure.

1. The temperature field change in the high and low temperature test chamber is affected by the aging circuit power and heat dissipation capacity (wind speed). The device not only controls the power of the circuit, but also changes the layout of the circuit. The lower layer is filled with circuits as much as possible, and the power of the circuit is gradually reduced from the lower layer to form a power gradient, which is consistent with the wind speed of the test chamber to achieve the purpose of heat dissipation.

2. The test chamber adopts an electric heating high-temperature drying test chamber, and the air source comes from the bottom. Due to the load plate and aging plate of the test chamber, the wind speed gradually decreases from bottom to top. According to the characteristics of the wind speed of the test chamber, the aging board can be placed in the same direction as the wind direction of the test chamber to increase the ventilation area, reduce the wind speed barrier, and enhance the heat dissipation function of the high temperature test chamber.

3. According to the improvement measures, the DC/DC power supply of the power device is used as the test object, the temperature is set to 80°C, the test circuit power is 65W (1) gradually increased to 5200W (8) the circuit power of the high temperature test chamber is 520W, which is 5.6°C higher than the set temperature Meet the national standard requirements (8) ℃ or 8%).
Finally, optimize the temperature control of the high and low temperature test chamber to obtain accurate test results.

Temperature Humidity Chamber | Thermal Chamber | Climate Chamber is according to IEC60068-2-1 (GB/T2423.1) and IEC60068-2-2 (GB/T2423.2), IEC60068-2-78, IEC60598-1, GB/T2423.17, GB/T5170.2, GB/T5170.5. The climate chamber is used to test the CFL/LED which meets IES LM-80-08, electricity products, automative cars, home appications and mobiles.

What is Climate Chamber?

Climate chambers is used to simulate a temperature enviromental condistions, it may also be called environmental chambers or Thermal Chamber or Temperature Chamber. You can click the below videos to learn the details and also how to operate it.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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