Localized overheating during the heating process of a high-low temperature test chamber can lead to structural deformation, damage to electrical components, and even fire risks. Therefore, a multi-dimensional control strategy is needed for precise protection. The core logic lies in optimizing heat conduction paths, strengthening temperature monitoring mechanisms, and standardizing operating procedures to ensure uniform heat distribution and rapid response to abnormal conditions.
The internal heat conduction efficiency of the high-low temperature test chamber directly affects temperature uniformity. If the heating element is too close to the chamber wall, or if the sample placement obstructs air circulation, localized high-temperature zones can easily form. For example, when the test sample is in direct contact with the chamber wall, heat will be concentrated at the contact point through thermal radiation, causing the temperature in that area to be significantly higher than other locations. In this case, the sample layout needs to be adjusted to ensure a distance of at least 5 cm from the chamber wall, and a layered shelf design should be adopted to promote heat dissipation through air convection. Furthermore, some high-end models add baffles inside the chamber to force air circulation and break up thermal stratification, keeping the temperature deviation within ±2℃.
The power matching and control accuracy of the heating system itself are crucial to avoiding overheating. Excessive heating element power or improper PID parameter settings can lead to temperature overshoot. For example, during rapid heating, if the controller fails to cut off the heating power in time, the temperature inside the chamber may exceed the set value and continue to rise. To address this issue, a segmented heating strategy is required: initially, rapid heating at full power, then switching to a low-power sustaining mode when approaching the target temperature, while using solid-state relays for millisecond-level response control. Some devices are also equipped with heating element overheat protection devices, which automatically cut off power to the affected area when a local temperature exceeds a safety threshold to prevent component burnout.
The layout and calibration accuracy of temperature sensors directly affect the timeliness of overheat warnings. Traditional designs typically install a single sensor in the center of the chamber, but this fails to capture temperature differences in edge areas. An improved solution involves adding platinum resistance temperature sensors at the four corners and center of the chamber, forming a multi-point monitoring network. When the temperature at any point deviates from the set value by more than 3°C, the system immediately initiates a cooling program and triggers an audible and visual alarm. Furthermore, the sensors must be calibrated regularly using a standard thermometer to avoid measurement errors caused by oxidation or drift. For example, platinum resistance sensors exposed to humid environments for extended periods may experience irreversible resistance changes, necessitating replacement to ensure data accuracy.
The coordinated operation of the refrigeration system is crucial for mitigating overheating during the heating phase. When the high-low temperature test chamber rapidly heats up from a low temperature, if the refrigeration compressor does not stop operating promptly, the clash between hot and cold temperatures can lead to localized condensation or even icing, further hindering heat transfer. Modern equipment utilizes dynamic energy regulation technology to achieve dynamic matching of cooling capacity: during the heating phase, the compressor reduces its speed to decrease cooling output, while the solenoid valve closes the refrigerant circulation path to prevent residual refrigerant from absorbing heat. Some models also feature a preheating function, preheating the refrigeration system before starting the heating process to prevent interference from the low-temperature medium.
The installation environment and operating procedures also affect the risk of overheating. The high-low temperature test chamber should be kept away from direct sunlight and maintained at least 60 cm away from walls to ensure unobstructed heat dissipation. If the ambient temperature exceeds 35°C, external air conditioning or forced ventilation is required to lower the room temperature and prevent frequent compressor shutdowns due to overheat protection. Operators must avoid suddenly opening the chamber door during the heating process. High-temperature steam can cause burns, and the influx of cold air from outside can cause a sudden drop in temperature, exacerbating thermal stress damage to the equipment. If sampling is required midway, equipment operation should be paused and the temperature allowed to drop to a safe range before proceeding with the operation while wearing heat-resistant gloves.
Preventative maintenance is a long-term solution to reduce overheating failures. Monthly cleaning of the condenser fins is necessary to prevent decreased heat dissipation efficiency. Quarterly checks for leaks at refrigeration pipe connections should be performed, and environmentally friendly refrigerant should be replenished as needed. Annual calibration of the control system by a professional engineer is required to ensure that PID parameters match the actual operating conditions of the equipment. By establishing standardized maintenance procedures, the failure rate caused by overheating can be reduced by more than 80%.
The heating process of the high-low temperature test chamber requires a comprehensive approach, including optimized heat conduction, precise control of the heating system, multi-point temperature monitoring, coordinated refrigeration system operation, standardized operating environment, and preventative maintenance, to construct a multi-layered protection system. This systematic solution not only prevents equipment damage caused by localized overheating but also extends the overall lifespan of the machine, providing a stable environment for reliability testing.
