Electric heating design data

Electric heating design data

Release date: 2012-07-13 View count: 1671 Font size: [large, medium, small]

Measurement unit

1. Power: W, Kw 1Kw=3.412BTU/hr British thermal unit/hour=1.36 (horsepower)=864Kcal/hr

2. Weight: kg 1Kg=2.204621b (pounds)

3. Flow rate: m/min

4. Flow rate: m3/min, kg/h

5. Specific heat: Kcal/(kg ℃) 1Kcal/(Kg ℃)=1BTU/hr ° F=4186.8J/(Kg ℃)

6. Power density: W/cm2 1W/cm2=6.4516 W/cm2

7. Pressure: Mpa

8. Thermal conductivity: W/(m ℃) 1 W/(m ℃)=0.01J/(cm s ℃)=0.578Btu/(ft.h. F)

9. Temperature: ℃ 1F=9/5 ℃+32 1R=9/5 ℃+491.67 1K=1 ℃+273.15

Electric heating power calculation

The calculation of heating power has the following three aspects:

● Power during operation ● Power during startup ● Heat loss in the system

All calculations should be considered in the worst case scenario:

● The lowest ambient temperature ● The shortest operating cycle

● Maximum operating temperature ● Maximum weight of heating medium (maximum flow rate for flowing medium)

Steps for calculating heater power

Draw a heating process flowchart based on the process (without involving material form and specifications).

Calculate the heat required for the process.

Calculate the heat and time required for system startup.

Redraw the heating process flowchart, consider appropriate safety factors, and determine the total power of the heater.

Determine the sheath material and power density of the heating element.

Determine the form, size, and quantity of the heater.

Determine the power supply and control system of the heater.

The symbols in the formula have the following meanings:

P power: kW Q heat dissipation: W/m for pipelines; The plane is W/m2

Weight of m1 medium: kg λ Thermal conductivity of insulation materials: W/mk

Specific heat of c1 medium: kcal/kg ℃ δ Insulation material thickness: mm

M2 container weight: kg d pipeline outer diameter: mm

Specific heat of c2 medium: kcal/kg ℃ L Pipeline length: m

The weight or flow rate of the medium increased by m3 per hour is kg/h, and the heat dissipation area of the S system is m2

Specific heat of c3 medium: kcal/kg ℃ △ T Difference between medium and ambient temperature or temperature rise: ℃

Heating time: h

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