Refrigeration characteristics and performance of high and low temperature chambers

High and low temperature chambers are a common testing equipment widely used in industries, research institutions, aerospace and other fields. By simulating extreme weather environments more realistically through the cyclic changes of high temperature, low temperature, and humidity, accurate test results can be obtained.

Working principle of high and low temperature chamber:
The heating process of the high and low temperature chamber is to generate heat after the wires in the heating system are electrified, and then transmit the heat generated by the air circulation system to the studio through circulating air to achieve the heating purpose. Due to its fast heating speed and high heat output, it has been widely used. Some users usually have high requirements for heating rate and high temperature range. According to this principle, it is possible to add wires and adjust the control system accordingly to meet this requirement.

Cooling is the core equipment of this process, which is a compressor. The compressor compresses low-temperature and low-pressure gases into high-temperature and high-pressure gases, which are converted into liquids through the condenser. The evaporator evaporates these liquids, enters low-temperature and low-pressure gases, and enters the compressor.

Therefore, continuous circulation absorbs a large amount of heat, and finally completes cooling. The heat generated by the compressor operation is carried away by the fan. Energy control devices are often added to equipment to control cooling energy and energy consumption, in order to achieve the goal of minimum energy consumption and maximum temperature, and reduce costs.

In addition to refrigeration and heating, the equipment should also be equipped with a humidity control system, humidification or dehumidification to meet the necessary humidity during the working process.

Refrigeration characteristics and performance of high and low temperature chambers:
In addition to components such as compressors, pressure accumulators, condensers, and dryers, the refrigeration system of the high and low temperature test chamber also includes several parts such as capillaries, solenoid valves, evaporators, and pressure protection. The combination of mechanical refrigeration and liquid nitrogen refrigeration is used, which consists of two parts and each part is a relatively independent refrigeration system. However, due to the low requirements for testing temperature, the cascade refrigeration method is often used.

The high and low temperature chamber is equipped with two sets of refrigeration compressors. If the equipment in the test chamber experiences temperature instability, a method can be used to troubleshoot it. Temperature instability is usually caused by a lack of refrigerant. Everyone can see the discharge pressure and suction pressure of the compressor. If the pressure value of the equipment is low, and the suction is removed at the pressure, this is the volume problem of the refrigerant.

In addition, the exhaust and suction pipes of the test chamber compressor should also be inspected. If the exhaust pipe temperature is not high and the suction pipe temperature is not low, refrigerant needs to be added. If the temperature of the equipment in the test chamber is unstable, it is necessary to check whether the refrigeration compressor can be started during the operation of the test chamber. If it can be started and used normally, it indicates that the main power supply is stable, and then check if there are any electrical issues. If the electrical operation is normal, the cause should be checked from the refrigeration system.

When using a high and low temperature test chamber for testing, what should be done if condensation occurs on the testing equipment or the tested product?
In the experiment, the humidity in the evaporator and air duct inside the chamber is transformed into water vapor after high-temperature drying, and then the internal air is replaced under the action of dry air; While strengthening the sealing, insulation materials can be placed at the bottom of the equipment to isolate the bottom of the box from the inside of the equipment and reduce the formation of water. Dehumidifiers can also be used to achieve low humidity control according to different environments at that time.

During testing, cold air is sent into the chamber and replaced with moist air, which is also a common method of humidity control “dehumidification” and one of the methods to solve moisture. In addition, substances such as activated carbon or desiccants with strong hydrophilicity can be placed in the chamber to adsorb the moisture inside. At the end of the experiment, by reducing the temperature rise rate and compressing the temperature difference between the tested product and the air inside the instrument chamber, the surface condensation phenomenon of the tested product can be greatly reduced.

Changes in temperature and humidity conditions are likely to cause condensation in the high and low temperature chamber. It must be noted that both the condensation generated on the surface of the product and the condensation inside the box can greatly damage the test piece. Therefore, we need to regularly inspect the equipment to avoid condensation.

Handling common problems with high and low temperature chambers:
1. What is the reason for the difficulty in opening the chamber door?
This may be because wet air enters the irregular small holes on the contact surface between the door and the door cover, forming condensation. When the door is closed, the condensed water discharges the air from the holes and forms a negative pressure. The sealed magnetic force and pollution relay can cause mixing and attraction. Later, when opening the high and low temperature chambers, it will be more difficult. This situation can be solved by using soap water to clean the door seal, Ensure its elasticity and smoothness, while eliminating condensation by applying talcum powder.

2. What can sometimes cause noise from laboratory equipment?
The reason for the looseness of screws, nuts, etc. fixing the compressor of the testing equipment, or the looseness of the equipment’s water connection plate; A considerable amount of refrigerant oil entering the evaporator of the equipment will also emit a “gurgling” sound of bubbles; Furthermore, due to reasons such as cylinder detachment, loose compressor springs, severe wear of internal parts, and poor lubrication, abnormal noise is caused by cylinder scraping.

The reason why pipelines vibrate is because they are suspended for a long time, which makes it easier to experience co seismic phenomena. The noise increases significantly and exhibits periodic fluctuations. When pressing into a part that is prone to vibration, the noise is significantly reduced or eliminated when pressing into a certain part. Use buffering, reinforcement, isolation and other methods and measures according to different conditions, such as vibration reducing mortar, rubber sleeves, etc. Poor vacuum evacuation of equipment can also cause “gurgling” sounds, and may also be caused by equipment malfunctions. Operators can investigate and handle these situations one by one.

3. Can it be reused after being stored for a long time?
After placing the high and low temperature chambers for a long time, it is necessary to clean them properly and ensure that the components are in good condition before conducting equipment testing. If the equipment can operate normally, the testing work can be carried out again.

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.

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.

Please feel free to contact us if you need any support.
Tech Dep: Service@Lisungroup.com, Cell/WhatsApp:+8615317907381
Sales Dep: Sales@Lisungroup.com, Cell/WhatsApp:+8618117273997

Tags：GDJS-015B