Selection criteria for U-shaped electric heating tubes:
1. Internal dimensions of the tank, length x width x height, and liquid level height.
2. Process temperature, starting temperature, and ending temperature.
3. The process requires a heating or cooling time (h).
Heat exchange (heating, cooling):
Q=V × C × r × β (t2-t1)/T (kcal)
V: Solution volume (liters)
C: Specific heat of solution (kcal/L × ℃)
r: Specific gravity (kg/L)
T1: Initial temperature of the solution
T2: Termination temperature of solution
β: Heat loss coefficient (taken as 1.10-1.30)
If Q is positive, it is the amount of heat required for heating up
If Q is negative, it is the required cooling capacity for cooling
T: Heating or pre cooling time h (hours)
Electric thermal equivalent (electrolytic heat):
Q＝0.864×I×V（Kcal/h）
I: Total current A V: Slot voltage V
Determination of heat exchange area S of heat exchanger:
S＝Q/K×ΔT×t
Q: Heat exchange capacity (kcal)
K: Heat transfer coefficient kcal/m2 × hr × ℃ (refer to heat transfer coefficient table V)
V: Solution volume (liters)
Δ T: Average temperature difference
t: Set heating (cooling) time (h)
Selection:
Determine the heat exchange area of the heat exchanger based on calculations, and determine the number and shape of heat exchanger groups according to the size of the tank (reactor), generally "U", "W", "L",
Coiled tube. When heating, the heat exchanger is placed at the bottom of the container, and the cooling is placed below the liquid level by 100mm, resulting in a "one" shape of the product. Our factory can select models and provide design solutions for users.

Precautions for electric heating tubes
1. The component is allowed to operate under the following conditions:
(1) The relative humidity of the air shall not exceed 95%;
(2) The working voltage should not exceed 1.1 times the rated value, and the casing should be effectively grounded.
2. When the heating medium is liquid, the effective length of the element (H1 or H2) must be completely immersed in the liquid. The heating part of the component should be at a certain distance from the container wall, usually 50-60mm or more.
3. Heating elements for liquids must not be used to heat gases or solid objects.
4. When heating liquid components, if scale or carbon deposits are found on the surface of the pipe, they should be cleaned before use to avoid affecting the service life of the component and reducing thermal efficiency.
5. When melting light metals or solid materials such as nitrate, alkali, asphalt, paraffin, etc., heating should be carried out by reducing the voltage and starting. The rated voltage can only be increased after all solid heating media have melted.
6. When heating nitrate, safety measures should be considered to prevent explosion accidents.
7. The wiring part of the component should be placed in the insulation layer, outside the heating room, and avoid contact with corrosive and explosive gases. The outlet end must be kept dry and clean to avoid flashover or short circuit. Do not apply excessive force when wiring.
8. A small amount of paste may overflow from the end of the component. This is a sealing material that does not affect its use. After the power is turned off, wipe off the overflow.
9. The components should be stored indoors with air circulation, relative humidity not exceeding 85%, and no corrosive gases.
10. When the cold insulation resistance of a component is less than 1 megaohm after being used for a period of time and being exposed to moisture for a long time, it can be baked in a drying oven at a temperature of around 200 degrees Celsius, or the voltage can be reduced and directly heated to remove moisture until it returns to normal.