Product Heatup Calculation

Definition of Heat-up:

Heat or energy is transferred from one substance to another as the result of a difference in temperature.

OR

In a simple way, heat-up is a temperature difference between cold & hot. Heat flow is transferred from high temperature to low.

Calculation of Product heat-up

Heat-up = M x Cp x ∆T/860 ................ (i)

Where 

M = Mass of product (kg).

Cp = Specific Heat of product (Kcal/Kg Deg C).

∆T = Temperature difference between cold & hot (Deg C).

Why do we use 860 in the heat-up formula?

To convert KCal to KW/ hour.  

i.e.  4.184/3600 = 1/860                      

(1 Kcal = 4.184 KJ,  1 watt hour = 3600 joules).    

we will consider the Specific heat units in KJ/Kg K

If time period is considered in heat-up:

Heat-up = (M x Cp x ∆T)/ (860 x T) ................ (ii)

Where 

T = Time period (Hr).

Calculation of Mass

Mass = Volume x Product density ................... (iii)

If the flow rate is given then Mass

Mass = Flow rate x Product density ................... (iv)

Calculation of Volume

Volume of tank = π/4 x Tank Dia^2 X Tank Height ................... (v)

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Example:

Volume = 20 M3

Density = 1000 Kg/M3

Specific Heat = 4.2J/G Deg C

Ambient Temperature = 10 Deg C

Maintain Temperature = 120 Deg C

Time Period = 72Hours

Solution: 

First, we calculate the mass of the product as per equation (iii).

Mass = 20 x 1000 

M = 20000Kg 

Now we put all values in equation (i).

Heat-up = 20000 x 4.2 x (120-10) / 860

              = 20000 x 4.2 x 110 / 860

              = 9240000 / 860

              = 10744.2KW/hr

Heat required for 72hr time period:

Heat-up = 10744.2/72

Heat-up = 145.2KW