The design and calculation of electric heaters generally follow the following three steps:

The design and calculation of electric heaters generally follow the following three steps:

1. Calculate the power required to heat from the initial temperature to the set temperature within the specified time.

2. Calculate the actual power required to maintain the temperature of the medium while maintaining the same temperature.

3. Based on the above two calculation results, select the model and quantity of the heater. The total power is taken as the maximum of the two types of power and the coefficient of 1.2 is considered.

Formula:

1. Power required for initial heating

KW=(C1M1 △ T+C2M2 △ T) ÷ 864/P+P/2

In the formula, C1C2 represents the specific heat of the container and medium (Kcal/Kg ℃), respectively

M1M2 represents the mass of the container and medium, in kilograms

△ T is the difference between the required temperature and the initial temperature (℃)

H is the time required to heat the initial temperature to the set temperature (h)

Heat dissipation of container at final temperature P (Kw)

2. Power required to maintain medium temperature extraction

KW=C2M3 △ T/864+P

In the formula, the added dielectric kg/h per hour for M3 is copper wire on both sides of the inner core of the electric tracing cable. During normal operation, a voltage of 220V is applied between the wires, and the part that generates heat between the two wires is made of semi conductive plastic, and its conductivity changes with environmental temperature. When the ambient temperature increases, its resistance also increases, and the generated heat decreases. When the ambient temperature rises to a certain value, the current inside the semi conductive plastic decreases to the minimum value, and the heat generated by the heating strip is close to zero. From the structure and principle of the electric heating strip, it can be inferred that the length of the electric heating strip can be arbitrarily cut according to the required heat output. An increase in the length of the electric heating strip is equivalent to an increase in the load between two power lines; A decrease in length is equivalent to a reduction in load between two power lines. The wires at both ends of the electric heating strip cannot be short circuited, and when the electric heating strip intersects and overlaps, it does not affect its working performance. It can automatically adjust the heat release according to the temperature.

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