1 How to control temperature and humidity ?

The high and low temperature test chamber is a product placed at a specified temperature and humidity to evaluate its ability to withstand high and low temperatures, as well as humidity. Therefore, the high and low temperature damp heat test chamber has the ability to simultaneously heat, cool, humidify, and dehumidify.

The heating device of the high and low temperature damp heat test chamber is the key link to control whether the high and low temperature damp heat test chamber heats up; It outputs a voltage to the relay when the controller receives a temperature command, with approximately 3-12 volts of DC applied to the solid-state relay; Its communication end is equivalent to a wire connection; The contactor also simultaneously engages, and there is voltage at both ends of the heater to generate heat. The circulating fan drives the heat to the box, causing the high and low temperature humidity test box to heat up, and the temperature will soon reach your set value;

The controller adjusts the on-off state of the solid-state relay by adding it; We adjust the heat generation by observing the heating output on the screen in the high and low temperature humidity test chamber; This is temperature control above 89 degrees, how to control temperature stability below 89 degrees? How much heat output does the high and low temperature wet heat test chamber generate through solid-state relays on one side; Furthermore, dynamic equilibrium is achieved by cooling through a compressor refrigeration cycle; The temperature remains constant.

Cooling of the high and low temperature humid heat test chamber is an important step in determining the performance of a high and low temperature humid heat test chamber. It includes four major components: compressor, condenser, throttling device, and evaporator. The compressor is the heart of the refrigeration system, which sucks in low-temperature and low-pressure gas, turns it into high-temperature and high-pressure gas, condenses it into liquid to release heat, and takes away the heat through the fan. Therefore, the hot air is located under the high and low-temperature humid heat test chamber, and then throttled to become low-pressure liquid. After passing through the evaporator, it becomes low-temperature and low-pressure gas and returns to the compressor; The refrigerant absorbs heat in the evaporator to complete the gasification process and absorb heat, achieving the purpose of refrigeration and completing the cooling process of the high and low temperature wet heat test chamber.

The humidification system and heating system of the high and low temperature wet heat test chamber are roughly the same; It is the process of heating water into steam by a heater; Complete the humidification purpose of the high and low temperature wet heat test chamber.

The dehumidification system of the high and low temperature wet heat test chamber is also completed by the refrigeration system, and the evaporator is placed inside the high and low temperature wet heat test chamber; It is relatively cold, and in the high and low temperature humid heat test chamber, high humidity gas condenses into liquid when it meets cold objects; The high humidity gas in the box will be reduced repeatedly, achieving the purpose of dehumidification.

2 Working principle

The professional production of high and low temperature test chambers includes various constant temperature chambers, drying chambers, vacuum drying chambers, electric hot air drying chambers, etc. Below, we will introduce the heating and cooling working principles of high and low temperature test chambers:

• Working principle of heating in high and low temperature test chambers: The heating system of high and low temperature test chambers generally uses nickel chromium alloy electric heating wires for direct heating. When the equipment is working, the circulating fan causes convection in the air inside the chamber, taking away the heat generated by the heating wires, thereby achieving the effect of heating the air inside the chamber; The control system adjusts the conduction time of the heating wire through a microcomputer, achieving dynamic balance between heating heat and heat loss, and achieving temperature control.

• The refrigeration process of the high and low temperature test chamber is as follows: the refrigerant is adiabatically compressed to a higher pressure by the compressor, consumes work to increase the exhaust temperature, and then the refrigerant exchanges heat with the surrounding medium through the condenser at an isothermal state, transferring heat to the surrounding medium. After the refrigerant undergoes adiabatic expansion through the shut-off valve, the temperature of the refrigerant decreases. The refrigerant absorbs heat from objects at higher temperatures through an evaporator, causing the temperature of the cooled object to decrease. This cycle repeats itself to achieve the goal of cooling down.

3 Reasons and solutions for some problem

• If the temperature set in the high and low temperature test chamber does not reach the desired level, it may be due to a faulty battery swapping humidification tube. You can first contact the manufacturer for on-site repair or directly replace the high and low temperature test chamber with a new one. If the temperature change during the high temperature test does not reach the set temperature value, the electrical system can be checked and the faults can be investigated one by one.

• It is also possible that the temperature probe is broken, causing the equipment to not work when the water temperature is below the set temperature of 37 degrees.

• The delay time of the temperature acquisition system is too long or the heating tube is aging or damaged, resulting in the equipment not working when the actual water temperature is below 37 degrees, or working but the temperature cannot rise.

• If the temperature rises directly and causes overheating protection, the controller will malfunction and the control instrument needs to be replaced.

• If the temperature overshoot is strong, the PID setting parameters need to be set first.

• If the temperature of the high and low temperature test chamber rises slowly, it is necessary to check the air circulation system to see if the air circulation adjustment baffle is opened normally. If the temperature of the high and low temperature test chamber rises quickly, check if the motor of the air circulation is running normally.

The high and low temperature test chamber has a time limit for use, so the operation time is too long, which inevitably leads to various high and low temperature test chamber failures. Regular maintenance and upkeep should be paid attention to, which can generally be largely avoided. If encountering significant technical difficulties, it is necessary to promptly contact the manufacturer for solutions.

Our company can develop high and low temperature testing equipment according to user needs. This equipment is used to assess the adaptability of electrical, electronic, mechanical products or materials under temperature cycling changes, as well as the storage and use of products under high or low temperature environmental conditions. Widely used in industries such as aerospace products, information electronic instruments and meters, materials, electrical engineering, and electronic products.