Working principle of laboratory constant temperature and humidity machineedit

Principle of refrigeration

The high-pressure liquid refrigerant flows out through the filter and enters the evaporator through capillary throttling and pressure reduction. Due to the decrease in pressure, the refrigerant continuously absorbs the heat transferred from the air to the evaporator in the evaporator and evaporates into vapor. The vapor is then sucked in by the compressor. The compressed high-temperature and high-pressure gas enters the condenser, and the heat is taken away by the condenser's heat dissipation. The refrigerant becomes a high-pressure and low-temperature liquid, and then passes through the filter to the capillary tube. The cycle continues to remove the indoor heat from the outdoor and reduce the indoor temperature. .

Heating principle

When the temperature in the conditioned air is lower than the required temperature, the computer controller of the constant temperature and humidity machine will turn on the electric heater to heat the air and send it to the conditioned room through a fan to achieve the purpose of heating.

Dehumidification principle

When the humidity in the conditioned air is greater than the required value, the compressor is started for refrigeration, the air is cooled to below the dew point temperature through the evaporator, and the moisture in the air is precipitated to achieve the purpose of moisture.

Humidification principle

When the relative humidity of the conditioned air is lower than the required value, the computer controller of the constant temperature and humidity machine makes the electrode humidifier work, and the water is heated and boiled into steam, which is sent to the air-conditioned space through a fan to achieve the purpose of humidification.

Essentials for daily maintenance of laboratory constant temperature and humidity machineedit

1. As the value of temperature (humidity) cabinet is generally relatively high, we recommend that it be placed in a relatively benign temperature environment. Our empirical temperature value is 8℃~23℃. For laboratories that do not have this condition, it must be equipped Appropriate air conditioner (air-cooled) or cooling tower (water-cooled).

2. Adhere to dedicated professional management. Qualified units should send special personnel to the supplier’s factory for training and learning from time to time to obtain more professional maintenance and repair experience and capabilities.

3. Regularly (every 3 months) cleaning the condenser: For compressors with air-cooled cooling, the condensing fan should be regularly overhauled, and the condenser should be decontaminated and dust-removed to ensure good ventilation and heat exchange performance; for the compressor In the case of water-cooled cooling, in addition to ensuring the inlet water pressure and inlet temperature, the corresponding flow rate must be ensured, and the inside of the condenser must be cleaned and descaled regularly to obtain its continuous heat exchange performance.

4. Clean the evaporator (dehumidifier) regularly (every 3 months): due to the different cleanliness levels of the test samples, under the action of forced air circulation, a lot of small particles such as dust will condense on the evaporator (dehumidifier), which should be carried out regularly Clean.

5. Cleaning and balancing of circulating fan blades and condenser fans: similar to cleaning the evaporator, because the working environment of the test chamber is different, a lot of small particles such as dust will condense on the circulating fan blades and condenser fans, so they should be cleaned regularly .

6. Waterway and humidifier cleaning: If the waterway is not smooth and the humidifier is fouled, it will easily cause the humidifier to dry out, which may damage the humidifier. Therefore, the waterway and humidifier must be cleaned regularly.

7. After each test, set the temperature near the ambient temperature, work for about 30 minutes, then cut off the power supply, and wipe clean the inner wall of the working chamber.

8. If the equipment needs to be relocated, it is best to proceed under the guidance of technicians to avoid unnecessary damage or damage to the equipment.

9. If the machine is stopped and not used, the product should be energized every half a month, and the energization time should not be less than 1 hour.

10. Then: As the environmental test chamber is basically composed of multiple electrical, refrigeration and mechanical systems, once the equipment has problems, the entire equipment should be inspected and analyzed comprehensively and systematically.

Generally speaking, the process of analysis and judgment can be "outside" and then "in", that is, first eliminate external factors, such as cooling water, power supply, etc., after completely eliminating external factors, according to the failure phenomenon, the equipment is first systematically decomposed, and then Comprehensive analysis and judgment of the system, you can use the backward method to find the cause of the fault: first, check whether there is a problem with the electrical system according to the electrical wiring diagram, and finally find whether there is a problem with the refrigeration system. Before clarifying the cause of the failure, you must not disassemble or replace parts, so as not to cause unnecessary trouble.