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Heating element distribution and thermal field control principle of high temperature box laboratory electric furnace

Publish Time: 2024-11-28
The distribution of heating elements and thermal field control of high temperature box laboratory electric furnace are crucial to achieve accurate experimental temperature conditions and uniform heating effect.

First, the distribution of heating elements directly affects the uniformity of the temperature field in the furnace. Common heating elements include resistance wire, silicon carbon rod, etc. In the design of the furnace of high temperature box laboratory electric furnace, the surrounding type, upper and lower layered type and other distribution forms are usually adopted. For example, the surrounding type distribution is to arrange the heating elements evenly along the four sides of the furnace. This method can transfer heat from the four sides to the center, which is suitable for furnaces with smaller sizes and higher temperature uniformity requirements. For furnaces with larger volumes, the upper and lower layered distribution is more common, that is, heating elements are set in both the upper and lower parts, which can effectively avoid the uneven thermal field caused by the temperature difference between the upper and lower parts. Through reasonable layout, the heating elements form a relatively balanced heat radiation area in the furnace, reduce local overheating or overcooling points, and provide a stable thermal environment for experimental samples.

Secondly, the principle of thermal field control is based on the control of the power of the heating elements. Through the temperature control system, the power supply of the heating element is adjusted according to the preset temperature value and the actual temperature feedback in the furnace. When the temperature in the high temperature box laboratory electric furnace is lower than the set temperature, the power of the heating element is increased to generate more heat; otherwise, the power is reduced. For example, using the PID control algorithm, the proportional link quickly adjusts the power output according to the size of the temperature deviation, the integral link eliminates the steady-state error, and the differential link predicts the temperature change trend and adjusts in advance, so as to accurately control the temperature rise rate and stabilize it at the set value. At the same time, some advanced electric furnaces can also independently control the heating elements in different areas, perform local power compensation for areas with uneven thermal fields, and further optimize the uniformity of the thermal field.

Furthermore, the interaction between the heating elements and the internal structure of the furnace also affects the thermal field. The material, shape, and internal reflective plates, heat shields and other components of the furnace will change the transfer and distribution of heat. For example, the use of a reflective plate with high reflectivity can concentrate the heat on the sample area and improve the heating efficiency; while the heat shield can reduce the heat loss to the furnace wall, so that more heat circulates inside the furnace, which helps to stabilize the thermal field. By rationally designing the coordination of these internal structures and heating elements, the thermal field can be flexibly adjusted under different experimental requirements, such as reducing the obstruction of the heat shield and reflector when rapid heating is required, and enhancing their role in the insulation stage.

Finally, in the electric furnace with multi-temperature zone control, the distribution and regulation of heating elements in different temperature zones are more complicated. Each temperature zone has independent heating elements and temperature sensors, and the temperature gradient setting of different temperature zones is achieved through zoning control. For example, in the gradient heat treatment experiment of materials, according to the temperature requirements of different parts of the sample, the power of the heating elements in each temperature zone is accurately controlled to make the temperature transition between adjacent temperature zones smooth and stable, meet the needs of special experimental processes for complex thermal field distribution, and provide precise thermal processing conditions for scientific research and material development.
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