Working System of Constant temperature and humidity test chamber
Judie Wang
Environmental test chambers factory(professional technical customization&after-sales, with 48 Invention Patents)
Refrigeration system：The low temperature is generated by the refrigeration system. The refrigeration system includes four major processes: compression, condensation, throttling, and evaporation. The compressor compresses the refrigerant into a high-temperature and high-pressure liquid. The liquid refrigerant dissipates heat through the condenser to normal temperature and high pressure. It is throttled and sprayed into the evaporator through the throttling device (expansion valve, capillary tube). The atomized refrigerant evaporates into a gaseous state to absorb heat to complete the cooling. The gaseous refrigerant returns to the compressor to continue the compression cycle.
Cascade refrigeration system: When the temperature needs to be lowered to -55℃, -60℃, -70℃, etc., R23 refrigerant is required.R23 refrigerant has a lower boiling point, so the working pressure is higher and the temperature is higher. In order to cool it better, it is far from being effective to just dissipate the heat, so a low temperature is required to cool it. At this time, the cooling capacity of the first-stage compressor (conventionally using R404A refrigerant) is used to pre-cool the second-stage refrigerant after heat dissipation through a plate heat exchanger. At this time, the R23 refrigerant in a low temperature state enters the evaporator through the throttling mechanism to complete the cooling.
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Heating system: The high temperature of the equipment is directly heated by the electric heating wire, and the heat is evenly distributed in every corner of the box through the air supply system. The electric heating wire of the ceramic heating rack is used for heating, and the heating tube power is calculated according to the actual temperature range and the size of the box.
Control method: The controller PID calculus data determines the output ratio according to the set and actual temperature conditions, and controls the on-off ratio of the solid-state relay to realize the power supply of the heating wire.
Environmental test chambers factory(professional technical customization&after-sales, with 48 Invention Patents)
1 个月Clean the air duct and radiator at regular intervals to ensure smooth air circulation and cooling and heating efficiency. If a fault occurs, general problems such as damaged temperature sensors and blown heating wires are relatively easy to diagnose and repair. Regularly replace the water and filter element of the humidifier, check the accuracy of the humidity sensor, etc. For example, the humidity sensor may have reduced accuracy due to long-term exposure to high humidity, and needs to be calibrated or replaced regularly. In addition, the mutual influence of temperature and humidity may cause some complex fault conditions, increasing the difficulty of maintenance.