What is Thermal Dispersion?
Thermal dispersion refers to the uniform distribution process of temperature inside a substance. Thermal dispersion is caused by the temperature difference between different parts of an object. In the absence of an external heat source and heat source, the inside of the object will gradually reach a thermal equilibrium state.
In real life, the size of thermal diffusivity is crucial to many phenomena and applications. In construction engineering, understanding the thermal diffusivity of materials helps to control the heat transfer efficiency of buildings under different climatic conditions. In electronic engineering, thermal diffusivity is crucial to the heat dissipation design of electronic equipment. It determines the uniformity of heat distribution and heat dissipation efficiency of the equipment during operation. It affects the stability and life of the equipment.
The size of thermal diffusivity is affected by many factors: type, structure, temperature, etc. Metals have higher thermal diffusivities. Because they have a compact crystal structure and good free electron mobility, which is conducive to the rapid transfer of heat. In contrast, non-metallic materials and insulators usually have lower thermal diffusivities. Because they lack free electrons or their crystal structure is not tight. Heat transfer is hindered to a certain extent.
How does a Flow Control System Work?
The flow control system consists of a flow meter, a flow regulator, and a control valve (pneumatic control valve or electric control valve). It can complete the fully automatic control of the flow value in the modern industrial process control system. It has a fast response and high control accuracy. The flow control system is widely used in chemical, food, biomedicine, environmental protection, metallurgy, water supply and drainage, papermaking, electricity and other industries.
Control principle
Any automatic control system is composed of three parts: sensor, controller and actuator. In this flow control system, the sensor is a variety of flow meters. The controller is a flow regulator, and the actuator is an electro-pneumatic control valve. This control system is a single-loop closed-loop control.
The electromagnetic flow meter collects the flow value downstream (or upstream) of the valve. When the flow value changes, it is fed back to the flow regulator promptly. The regulator compares and calculates the detected flow value according to the set value. Outputs the analog signal (4- 20mA or 1- 5V) to the control valve promptly.
Adjust the opening of the control valve to stabilize the flow value near the set value. When the flow value is stable, the control valve stops adjusting. Once the control flow value is disturbed, the system starts a new adjustment process. Therefore, automatic control is a stable system, not a permanent system. This places a relatively high demand on the performance of the control valve and the regulator to adapt to the frequent adjustment process.
