# Heat loss for containers

##### CALCULATE THE HEAT LOSS FOR CONTAINERS

To calculate heat losses on an insulated container, you have to know certain data. Required operating temperature, ambient temperature, the thickness of the insulation and conductivity, the total cooling area of the outer sheath and the nature of the environment.

 Q = A x Δt x k x s S x E
 Q = Total heat loss (W) A = The total cooling sheath surface (m²) k = The permeability of the insulation material (W/m°C) (Mineral wool 0.04) Δt = Difference in temperature (the difference between the operating temperature and the lowest ambient temperature). S = The thickness of the insulation (m) E = Safety factor (normally 0.8) s = Safety factor 1,2 -1.5 (1,2 indoor – 1,5 outdoor)

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 a 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.

Example

Frost protection of a round, standing tank

 Diameter = Ø 1500 mm Height = 3 m Dt = 40°C S(m) = The thickness of the insulation 50mm mineral wool k-Value = 0,04 Environment = The tank is placed within flammable surface
 Q = A x k x Dt x s (W) S x E

 Q = 15,9 x 0,04 x 40 x 1,2 = 763 W 0,05 x 0,8

Heatloss calculation for container

To make a calculation of heat losses on an insulated container you need to know certain data: required operating temperature, ambient temperature, the thickness of the insulation and conductivity, the total cooling surface of the outer jacket and the condition of the surroundings.

 Q = A x Dt x k x s S x E
 Q = Total heat loss (W) A = Total cooling sheath surface (m²) Dt = Difference in temperature (the difference between the operating temperature and the lowest ambient temperature) k = The permeability of the insulation material (W/m°C) (Mineral wool 0.04) S = The thickness of the insulation ( m ) s = Safety factor 1,2 -1.5 (1,2 indoors – 1,5 outdoors)

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.

Heating a round, standing tank of steel containing oil

 Diameter = Ø 1500 mm Height = 3 meter Dt = 40°C S(m) = The thickness of the insulation 50 mm mineral wool k-Value = 0,04 Environment = The tank is located indoors, oil retains can occur.
 Q = A x k x Dt x s S x E (W) Q = 15,9 x 0,04 x 40 x 1,2 0,05 x 0,8 = 763W

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