1、 The design and calculation of electric heating plays a very important role in electric heating systems. This chapter briefly introduces some calculations and designs in typical applications. If further research is needed, please refer to the relevant manuals. The design and calculation of electric heating are generally carried out in the following three parts:
1. Calculate the power required to heat to the set temperature within the specified time from the initial state as required.
2. Calculate the power required in actual work on the premise that maintaining the medium temperature is inconvenient.
3. For the selection of heater model and quantity, the total power shall be the maximum of the above two types of power, and the coefficient of 1.2 shall be considered.
Formula: 1. Power required for initial maintenance of heating Kw=(C1M1 △ T+C2M2 △ T)/863/H+P/2
P Heat dissipation of the container at final temperature Unit: kW
H is the time required to heat the initial temperature to the final temperature, in hours
M1 and M2 are the masses of the container and medium, respectively, in kilograms
C1 and C2 are the specific heats of the container and medium, respectively, in kilocalorie/(kg ℃)
△ T is the difference between the final temperature and the initial temperature, in degrees Celsius.
2. Power required to maintain medium temperature: Kw=C2M3 △ T/863+P
M3 is the unit of media added per hour: kilogram per hour.
2、 To facilitate people's design, this chapter provides some quick calculation formulas
1. Power required for static water and oil heating (regardless of vessel heat consumption) Kw=CM △ T/863/H
C: Specific heat kcal/(kg. ℃)
M: Mass kg △ T
H: Time: hours.
2. Power required for heating flowing water and oil (regardless of vessel heat consumption) Kw=CF △ T/14
C: Specific heat kcal/(kg. ℃)
M: Flow kg/min △
T: Temperature difference ℃.
3. Channel type air heating (normal pressure) Kw=F △ T/40
M: Flow meter 3/min
△ T: temperature difference ℃
40: Coefficient kW. min (m3/min)
Vout=Vin(Tout+273)/(Tin+273)
Vin, Vout: channel inlet and outlet flow rate
Tin, Tou: Channel inlet and outlet temperature ℃.