How to effectively reduce heat and cold in a rapid temperature change test chamber

The rapid temperature change test chamber is used to test the performance of various materials in various environments, such as heat resistance, cold resistance, dry resistance, and moisture resistance. It is suitable for testing the quality of products such as “electronics, electrical appliances, communications, instrumentation, vehicles, plastic products, metals, food, chemistry, building materials, medical treatment, and aerospace”.

I. Working principle of rapid temperature change test chamber:
A “binary cascade air-cooled refrigeration system” composed of a fully enclosed compressor is used. The cascade refrigeration system includes “a high-temperature refrigeration cycle and a connecting container during the refrigeration cycle” as an evaporative condenser. Note: The evaporative condenser also has the function of energy transfer, which transfers the internal heat energy of the working chamber through a two-stage refrigeration system to achieve the purpose of raising temperature.

The high and low refrigeration cycle in a rapid temperature change test chamber usually uses an “inverse Carrot cycle”, which consists of “two isothermal processes and two adiabatic processes.”. The process is as follows: After the refrigerant is adiabatic compressed by the compressor to a higher pressure, work is consumed to increase the exhaust temperature. After the refrigerant undergoes isothermal heat exchange with the surrounding media through the condenser, and the heat is transferred to the surrounding media, the refrigerant undergoes adiabatic expansion through the valve to do work. At this time, the temperature of the refrigerant will decrease. Later, the refrigerant can absorb heat from higher temperature objects such as evaporators to lower the temperature of the cooled object. This cycle repeats itself to achieve the purpose of cooling.

II. Refrigeration system of rapid temperature change test chamber:
The rapid temperature change test chamber and other parts are cooled by water cooling. Water cooling is currently a relatively mature technology in China, and it is also a commonly used means to solve harsh environments. Water cooling is a method of cooling by circulating water. Its main components are composed of a water tower, water pipes, and water pumps. The water cooling effect of the rapid temperature change test chamber is less affected by high temperature weather, and its cooling efficiency is high. Moreover, the test chamber has a long service life, and can reach a worse environment. At the same time, it has a significant effect on faster cooling and extremely low temperature retention.

As the water tower is a key part of water cooling, the water capacity of the water tower is generally recommended to be 8~16t. The water tower cannot be placed indoors, but can only be placed on the roof or downstairs, and maintenance is also troublesome. The water pipes must be wrapped properly, otherwise they can easily be sunburnt or frostbitten. However, the production cost is higher than that of the air-cooled type, and the maintenance frequency and environmental factors of the equipment site are more than that of the air-cooled type. As the water cooling system is installed outdoors, its water tower Water pipes are prone to impurities and dirt.

III. How to deal with the problem that the low temperature of the rapid temperature change test chamber cannot meet the test index?
In fact, when the low temperature cannot meet the test index, we need to observe the temperature change, whether it is because the temperature drops very slowly or because there is a trend of recovery after the temperature reaches a certain value. For the former, it is necessary to check whether the working chamber is dried before conducting the low-temperature test, and then place the test samples in the working chamber after keeping the working chamber dry. In addition, it is also necessary to check whether the test samples in the working chamber are placed too much to allow sufficient circulation of wind.

After eliminating the above reasons, it is necessary to consider whether there is a fault in the refrigeration system. If so, contact the supplier and ask professional personnel for maintenance. The latter phenomenon is caused by the poor use environment of the test chamber, because the ambient temperature and location of the test chamber should meet the requirements.

IV. Rapid temperature change test chamber effectively reduces cold and hot solutions:
With the adoption of an intelligent automatic conversion expansion system that automatically adjusts the refrigerant flow based on the load+intelligent electric heating power data value (%) to match the temperature rise and fall (load) automatic simulation output power data output value, this design can save more than 30% of power compared to traditional designs.
1. During the operation of the rapid temperature change test chamber, please do not open the door unless absolutely necessary, otherwise the following adverse consequences may occur.
2. Avoid switching off and on the refrigeration unit within three minutes.
3. Please note that the test chamber must be securely and reliably grounded to avoid electrostatic induction.
4. Circuit breakers and over temperature protectors are intended to provide safety protection for the machine’s test items and users, and should be regularly inspected.
5. If a heating test object is placed in the chamber, please use an external power supply for its power control, and do not directly use the power supply of the test box. When placing high-temperature test materials for low-temperature testing, it should be noted that the time for opening the chamber door should be as short as possible.
6. It is absolutely prohibited to put explosive, flammable, and highly corrosive substances into the chamber for testing.
7. The lights should be turned off at all times except when necessary.
8. On any section perpendicular to the dominant wind direction, the sum of the test load cross-sectional areas shall not be greater than one-third of the working section at that location.
9. Do not start the refrigerator when the temperature exceeds 55 ℃ during the high temperature test.
10. Before making low temperatures, the studio should be dried at 60 ℃ for 1 hour.

V. Standard for use of fast temperature change test chamber:
1. Confirm that all accessories of the rapid temperature change test chamber can work normally, including the compressor, controller, and other accessories.
2. During the test, it is not allowed to easily open the chamber door, otherwise it will have a significant impact on the test results, and may also lead to scalding or frostbite of the user.
3. Before using the rapid temperature change test chamber, it is necessary to check whether the power supply is connected accurately and grounded. If the connected power supply voltage does not meet the requirements, it may affect the normal operation of the equipment, and serious safety accidents such as electric shock may occur.
4. During the operation of the rapid temperature change test chamber, the power terminal cover must be installed on the terminal board to prevent electric shock.

The rapid temperature change & humidity heat test chamber is a temperature and humidity test device, applied for aerospace products, information electronic instruments, electrical, electronic products, and various electronic components to test various products under the condition of rapid temperature change performance.

KWB-054D Rapid temperature change & humidity heat test chamber

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.

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