Definition
The high and low temperature humidity heat tester is a type of testing equipment used to simulate the performance of products in specific temperature and humidity environments. It uses controlled heating, cooling and humidification systems to accurately reproduce temperature and humidity parameters in the natural environment or specific operating conditions in an enclosed space to evaluate the weather resistance, reliability and stability of materials or products.
How it works:
The device operates on the principles of thermodynamics and fluid control. Its core is composed of a refrigeration circulation system, a heating system, a humidification system and an air circulation system. The refrigeration cycle mostly adopts compressor refrigeration to achieve cooling through refrigerant phase change. The heating system raises the temperature by means of a resistive heater; Humidification systems usually increase humidity with the help of steam generators or water tray evaporation; The air circulation system promotes the uniform flow of air in the box through the fan to ensure consistent temperature and humidity distribution. The control system adjusts the output of each subsystem in real time according to the set parameters to keep the environment in the box within the target temperature and humidity range.
Measurement method
Temperature and humidity measurements are usually carried out according to international standards such as IEC 60068 series or GB/T 2423 series. Platinum resistive or thermocouple sensors are used for temperature measurement, and capacitive polymer thin film sensors are mostly used for humidity measurement. The sensor is placed in the efficient working space of the box and transmits the signal to the controller via the data acquisition module. When measuring, it is necessary to follow the principle of point distribution stipulated in the standard, record the data of each measurement point after the stable operation of the equipment, and calculate the spatial uniformity and fluctuation. The formula for calculating uniformity can be expressed as: ΔT = max| T_i - T_avg|, where T_i is the temperature of each measurement point, and T_avg is the average temperature of each measurement point.
Influencing factors
The accuracy of test results is influenced by various factors. The cooling power and heating rate of the equipment itself determine the range and speed of temperature change. The response speed and accuracy of the humidification system directly affect the stability of humidity control. The insulation performance and sealing of the box will affect the energy consumption and internal uniformity; The design of air circulation wind speed and flow direction has a significant effect on the temperature and humidity distribution around the sample. In addition, sample placement, load size, and heat capacity may also change the actual environmental parameters in the chamber.
Applications:
This equipment is widely used in quality verification links in electronic appliances, auto parts, aerospace, building materials, packaging materials and other industries. In the electronics industry, it is used to test the electrical performance of circuit boards in alternating warm and humid environments; In the automotive sector, it is used to evaluate the adaptability of parts in cold or hot and humid regions; In materials research, it is used to analyze the thermal expansion and contraction and hygroscopic properties of polymer materials. These tests help identify design flaws, optimize product processes, and improve long-term reliability.
Key points of selection
The selection should comprehensively consider the testing requirements and technical parameters. The temperature range should cover the extreme environment that the product may actually encounter, the common range is -70°C to +150°C; Humidity typically ranges from 20%RH to 98%RH. The internal volume of the chamber should be reserved with sufficient space to ensure air circulation, and it is generally recommended that the sample volume should not exceed one-third of the volume of the studio. The temperature change rate is an important indicator, and the linear and nonlinear temperature control modes are suitable for different test standards. In addition, it is necessary to pay attention to the energy efficiency level, control accuracy, data logging function, and compliance with the standard system of the equipment to ensure that it is compatible with the existing laboratory processes.