2 replies to this topic

[Martyna]

Hello, first of all, I want to sorry every one for my english - it's not my native language. Sorry to say that, but I couldn't find as professional/helpful forum in my country, thats why I am looking for help here.

I need help with calculations:

There is a tank kept in temp. under 0deg. To keep the medium (water) above 4deg. in tank there is installed a coil. We know that this tank is losing Q=400kW. We know the geometry of the coil, material of it. The heating medium is water+glycol40% which has inlet temp. 80deg. The flow of it is 6m^3/s. We are looking for overall coefficient heat transfer.

Thats my idea for it:

I assume that the temp in tank is constant t=4deg so coil have to give to the water also Q, so:

m1*cp1*(t1-t2)=U*A*delta-t=Q

t2=t1-Q/m1/cp1 - outlet temp of heating medium 

 

U=Q/A/delta.t                                  where delta.t=(t1-t2)/ln((t1-t)/(t2-t))

 

From this algorithm U=600 (every thing in SI units). It looks strange for me. Isn't it too big?? 

Edited by Martyna, 28 November 2016 - 01:16 PM.

[latexman]

I'm sorry, I cannot follow your verbal description.  Draw a sketch.  Show all flows.  Show all temperatures.  Define the mediums.  Show all units.  Then scan it and attach.

[srfish]

If you can achieve a heat transfer of greater than  about 1700 inside the tubing, it is possible.