How to calculate heat flux in a hot water tank

[chetanladha]

Hi.
I wish to calculate the heat flux on a bottom plate of a hot water tank. Would simply (m*c*t)/area give me the correct results.
Please help?

 

[edgepflow]

Is the bottom plate sitting on the ground or elevated? Is the tank insulated?

 

[chetanladha]

Thank you for your response.
Yes the tank is insulated,and sitting on ground.

Now the upper surface of plate is in contact with the fluid (hot water). How can i find the heat flux?

 

[edgepflow]

Thank you for your response.
Yes the tank is insulated,and sitting on ground.

Now the upper surface of plate is in contact with the fluid (hot water). How can i find the heat flux?

There are some nice "freeware" packages that will compute this. PM me if you are interested.

If you want to calculate it yourself, do this:

q = U A (T-water - T-outisde)

where,

q = heat loss
U = heat transfer coefficient
A = surface area
T-water = water temperature inside tank
T-outside = outside air temperature.

The heat transfer coefficient is given by:

U = 1 / [ 1/hi + twall/kwall + tins/kins + 1/ho ]

where,

hi = natural convection heat transfer coefficient on inside of tank
twall = tank wall thickness
kwall = tank thermal conductivity
tins = insultation thickness
kins = insulation thermal conductivity
ho = natural convection heat transfer coefficient on outside of tank

Let me know if you need any help figure these values out.

 

[sardar]

Hello,

To calculate the heat flux in a hot water tank, you would need to use the formula Q/A = k*(dT/dx), where Q is the heat flux, A is the surface area of the bottom plate, k is the thermal conductivity of the material, and dT/dx is the temperature gradient across the bottom plate.

The formula you have mentioned, (m*c*t)/area, is used to calculate the total heat energy stored in the tank, where m is the mass of the water, c is the specific heat capacity, and t is the change in temperature. This is different from calculating the heat flux.

To accurately calculate the heat flux, you would need to know the thermal conductivity of the material, which can vary depending on the type of material and its thickness. You may also need to consider any heat loss due to convection or radiation.

I hope this helps. If you need further assistance, please provide more information about the specific conditions and materials of your hot water tank.

Best,