# Required power

##### CALCULATION OF REQUISITE POWER TO HEAT CONTAINERS AND ITS CONTENT.
• At heating of containers, must also the heat loss through the thermal insulation be taken into consideration.
• The calculation for this is carried out according to the previous page and be added to the calculated required power for heating.
• The calculation of the required power to increase the temperature in a container to a required temperature on an appointed time, data is required according to following:

Final temperature after heating, start temperature, thickness and conductivity, the thickness of the insulation and conductivity, the total cooling surface of the outer sheath and the nature of the environment. Also information about the volume of the container, the density of the content and heating permittivity and required heating-up time is required.

 Ph = V x G x c x th + Q h
 Q = Heat loss through the insulation (W) Ph = The required power to increase the temperature th degrees on h hours. V = The volume of the container (dm³) G = The density of the content (kg/dm³) c = The heating permittivity of the content (Wh/Kg°C) th = Required temperature rise (°C ) h = Heating-up time (Hours)
 NOTE! If the object is made of plastic material or if the content is temperature sensitive it is always recommended using self-limiting cable. If cable of parallel resistive or a series resistive type is chosen, shall the sheath temperature be calculated so that it does not exceed the temperature for the material or the medium in the container.
 Diameter = Ø 1500 mm Height = 3 meter Ambient & start temperature = 20°C Required temperature = 80°C Insulation D(m) = Mineral wool 0,05 m k-Value = 0,04 Environment = The tank is located indoors, oil retains can occur. The density of the content (G) = 0,9 (Kg/dm3) Heat permittivity (c) = 0,58 (Wh/Kg°C) Heating-up time (h) = 24 hours Ph = The required power to increase the temperature on the object to required temperature on h hours (W).

Volume V(l)= p x r² x h =p x 7,5² x 30=5298 dm3

 Ph = V x G x c x th h = 5298 x 0,9 x 0,58 x 60 24

P = Totalt required power (W)
P = Q + Ph = 468 + 6913 = 7381 W

The tank is made of steel and the oil withstands high temperatures so we choose a series resistive cable of teflon with high power per meter. Connection is done by temperature control.

We choose TCTR-cable with 28W/lm. This gives:

3 pcs heating cable loops á 86 meter TCTR 0,25 ohm 2460W / 230V