The programmable temperature rise cycle testing machine is a professional equipment used to simulate the performance changes of products in complex temperature environments. Its basic working principle involves the collaborative work of multiple systems.

（1） Temperature control system

1. Heating principle

-The testing machine is equipped with a heating device inside, usually using components such as electric heating wires or heating tubes. When temperature needs to be raised, the control system will energize the heating element to generate heat. Heat is transferred to the space inside the test chamber through air circulation or heat conduction, thereby increasing the temperature inside the chamber. For example, in some high-precision testing machines, PID (Proportional Integral Derivative) control algorithm is used to accurately control the heating power. The PID controller dynamically adjusts the output power of the heating element based on the difference between the set temperature and the actual temperature. If the actual temperature is lower than the set temperature, the proportional component will increase the heating power; The integration process will eliminate the static error of the system and gradually bring the temperature closer to the set value; The differential link can predict the temperature change trend, adjust the power in advance, prevent temperature overshoot, and achieve accurate control of temperature.

2.制冷原理

-The refrigeration system is a key component in achieving cooling. Generally, compressor refrigeration is used, and its working principle is similar to the refrigeration cycle of a refrigerator. The compressor compresses the gaseous refrigerant into a high-temperature and high-pressure gas, which is then dissipated through a condenser to turn the refrigerant into a high-pressure liquid. After passing through throttling devices such as capillaries or expansion valves, high-pressure liquid becomes low-pressure liquid and enters the evaporator. In the evaporator, the low-pressure liquid refrigerant absorbs heat from the test chamber and evaporates into a gaseous state, thereby reducing the temperature inside the chamber. This process continuously cycles to achieve the effect of continuous cooling. At the same time, the refrigeration system is also accurately regulated by the control system, which achieves precise temperature control and stable maintenance by controlling the start and stop of the compressor, the flow rate of the refrigerant, and other methods.

（2） Air circulation system

In order to ensure the uniformity of temperature inside the test chamber, the air circulation system plays an important role. There is a fan inside the testing machine, and when the fan is running, it will promote the circulation of air inside the box. Air flows from areas with higher temperatures to areas with lower temperatures, taking away heat and also bringing cold air from low-temperature areas to high-temperature areas, thus making the temperature in various positions inside the box tend to be consistent. For example, in some large temperature rise cycle testing machines, multiple sets of fans and reasonable air duct designs are used to ensure that the air can be evenly distributed throughout the entire testing space, avoiding situations where local temperatures are too high or too low.

（3） Program Control System

One of the core features of the programmable temperature rise cycle testing machine is its programmable function. Users can pre-set temperature change programs through specialized control software or operating interfaces. This program can include multiple temperature stages, such as heating stage, constant temperature stage, cooling stage, etc., and can set parameters such as duration and temperature change rate for each stage. During the experiment, the control system will automatically adjust the working status of the heating and cooling systems according to the program set by the user, achieving accurate temperature changes. For example, when simulating the working conditions of electronic products in a day night temperature difference environment, users can set a cyclic program of high temperature during the day and low temperature at night, and the testing machine will automatically run according to this program, truly simulating the temperature change process of the product in the actual usage environment.