1, first determine the working environment of the heating element
Generally, the law is to dry the air. The ratio of the length of the electric heating element to the power is 1:1. If the liquid is heated, a stainless steel heating tube is generally used. The ratio of the length of the tubular heater to the power is 1:2. Of course, depending on the specific situation, it can also be 1:3. If it is heating oil, the ratio is 1:2. Where the scale is serious, the heating pipe needs to reduce the surface load. It is best to design the power per meter not to exceed 2KW.
According to the working environment, the heating tube power is simply determined, and we need to know: 1. If the air is dry, there is a fan circulation. 2. If the air is dry, is there any temperature control (how many degrees is it controlled?). 2. If the liquid is heated, how high the water level is, whether there is pressure, the acidity and alkalinity of the liquid, and the scale of the water.
2, tubular heating element shape
According to the shape of the heating pipe, there are mainly a single-head heating pipe, a fin-shaped heating pipe, a flange heating pipe, and a U-shaped heating pipe.
3. Determination of specific details
Pipe diameter
Wall thinckness
Cold zone and heating zone
fastener
Voltage determination (wiring method)
The principle of heat generation: the current through the resistor to generate heat.
According to the electric heating law: the heat is proportional to the product of the square of the current and the resistance.
The principle of current thermal effect: electrons are accelerated in the electric field, get kinetic energy, have velocity, and then collide with other particles (atoms, molecules, atomic groups) to make other particles get kinetic energy, resulting in an increase in average kinetic energy and an increase in temperature.
When a current passes through a resistor, the resistor heats up and converts the electrical energy into heat. This phenomenon is called the thermal effect of the current.