Definition
The high-temperature, high-humidity and high-pressure test chamber is an experimental equipment that simulates harsh environmental conditions, which is mainly used to reproduce and evaluate the resistance and reliability of products under the combined action of high temperature, high relative humidity and high atmospheric pressure (usually higher than the standard atmospheric pressure) in the laboratory. It provides an accelerated aging or adaptive testing environment for materials, components and complete products by accurately controlling the temperature, humidity and air pressure parameters in the box, and belongs to an important branch of environmental reliability test equipment.
Principle
The core working principle of the device is based on thermodynamics, fluid dynamics and humidity control theory. The system usually consists of a cabinet, heating system, humidification system, pressure control system, refrigeration system, sensors and controllers. The heating system mostly uses electric heating elements to make the temperature in the box rise evenly through air circulation. Humidification systems often evaporate water into steam or ultrasonic atomization to introduce water vapor into the circulating airflow to increase humidity. The pressure control system is injected with compressed air or gas and adjusted with the exhaust valve to keep the pressure in the box at the set value. According to the temperature, humidity and pressure signals feedback from the sensor, the controller dynamically adjusts each actuator through the proportional-integral-differential algorithm to achieve stable and precise control of parameters.
Measurement method
During the test, the measurement of key parameters follows the relevant standard methods. Platinum resistance or thermocouple sensors are usually used for temperature measurement, and according to standards such as IEC 60068-2-1, the sensor must avoid direct radiation and air currents. Humidity measurement mostly uses capacitive polymer thin film sensors or dry and wet bulb methods, referring to standards such as IEC 60068-2-78, and regular calibration and pollution protection of the sensor should be paid attention to. Pressure measurement is generally carried out using piezoresistive or capacitive pressure sensors, which must cover the test range and refer to standards such as ISO 16440 for static pressure calibration. The measurement data is collected and recorded by the controller in real time, and some systems support data export for subsequent analysis.
Influencing factors
The performance of the test chamber is affected by a variety of factors. The tightness and thermal insulation of the box structure directly affect the pressure stability and energy consumption. The uniformity of the air circulation system is related to the consistency of the temperature and humidity field. The conductivity and cleanliness of humidification water may affect the accuracy of humidity control and the life of the equipment. The sensor accuracy and calibration cycle determine the measurement reliability. The response speed and anti-interference ability of the control algorithm affect the fluctuation range of parameters. In addition, the size, heat capacity and placement of the tested sample will also disturb the environment inside the box, which needs to be considered in the experimental design.
Applications
High-temperature, high-humidity, and high-pressure test chambers are widely used in many industrial fields. In the electronics and electrical industry, it is used to test the insulation performance and corrosion behavior of integrated circuits, printed circuit boards and packaging materials under high pressure of humidity and heat. In the automotive field, it is used to evaluate the reliability of automotive electronic components, connectors and seals in the engine compartment or under specific operating conditions; In the aerospace field, it is used to verify the functional maintenance of airborne equipment in high-altitude rapid decompression or humid and hot environments. In materials research, it is used to study the aging mechanism and life prediction of polymer materials, composites and coatings. In addition, it is also used in the reliability verification of consumer electronics, new energy battery modules, outdoor lighting equipment and other products.
Equipment selection
When selecting, it is necessary to comprehensively consider the technical parameters and usage requirements. In terms of technical parameters, attention should be paid to the temperature range, humidity range, pressure range, temperature rise and fall rate, humidity change rate, pressure control accuracy and working space size in the box, and these parameters should cover the test conditions specified in the relevant product standards. In terms of function, it is necessary to evaluate the programmability, data logging capabilities, safety protection functions, and remote monitoring support of the control system. In terms of equipment structure, it is necessary to examine the corrosion resistance of the liner material, the durability of seals and the convenience of maintenance. At the same time, it is necessary to confirm that the equipment meets or is compatible with domestic and foreign standards, such as IEC, ISO, GB, etc. Energy consumption, floor space and after-sales support are also factors that need to be weighed in the selection.