## BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

## BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

(OP)

hi

i'm batch heating a tank containing water

and need to raise the water temp in the

tank from 20degC to 60degC in 1 hour.

the tank water contents are not agitated.

i'm using an internal coil in the tank

as the heat exchanger. the hot water

entering is about 1.1 liters/sec at 80degC and 60degC exiting

the coil.

i've assumed an overall heat transfer coefficient

of 500 Watts/m2C for the internal coil.

what are the relevant formulas that would provide

a reasonably accurate surface area of the internal coil.

pumpmanplee

i'm batch heating a tank containing water

and need to raise the water temp in the

tank from 20degC to 60degC in 1 hour.

the tank water contents are not agitated.

i'm using an internal coil in the tank

as the heat exchanger. the hot water

entering is about 1.1 liters/sec at 80degC and 60degC exiting

the coil.

i've assumed an overall heat transfer coefficient

of 500 Watts/m2C for the internal coil.

what are the relevant formulas that would provide

a reasonably accurate surface area of the internal coil.

pumpmanplee

## RE: BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

Good luck,

Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

## RE: BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

you need volume of water you're trying to heat, you have a heat input in terms of m2 of the coil, temperature of the heating water ( use 70C as the average heat input figure), you can calculate average heat input rate required in terms of W.

what more do you need?

This is a very basic question though - student??

Remember - More details = better answers

Also: If you get a response it's polite to respond to it.

## RE: BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

TTFN (ta ta for now)

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## RE: BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

Perry's formula (shown below) for coil in tank

isothermal heating medium

is the formula i need,

however

it is for an agitated tank,

how do you adjust the formula for

a tank that is not agitated...

that is with my tank batch heating

application, there is no mechanical

mixing inside the tank, just simply

by convection.

pumpmnanplee

= = = = =

below copied from Perry's handbook...

" and over the entire surface, (2) liquid flow rates are constant, (3) specific

heats are constant for the process, (4) the heating or cooling

medium has a constant inlet temperature, (5) agitation produces a uniform

batch fluid temperature, (6) no partial phase changes occur, and

(7) heat losses are negligible. The developed equations are as follows.

If any of the assumptions do not apply to a system being designed, new

equations should be developed or appropriate corrections made.

Coil-in-Tank or Jacketed Vessel: Isothermal Heating Medium

ln (T1 − t1)/(T1 − t2) = UAθ/Mc (11-35)

where K1 = eUA/WC "

## RE: BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

Good luck,

Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

## RE: BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

yes, the U overall heat transfer coefficient

takes into account the combined conduction

& convection looking at the overall heat transfer

coefficient formula in my book),

so it takes into account the

mixing or non mixing inside the tank.

i used the 500 W/m2C from an internet reference

giving a range of 200 to 500 W/m2C

for coils immersed in water.

one other question i have in regards to Perry's handbook formula for:

Coil-in-Tank or Jacketed Vessel: Isothermal Heating Medium

ln (T1 − t1)/(T1 − t2) = UAθ/Mc (11-35)

where K1 = eUA/WC "

how come it does not take into account

the exit temperature of the fluid exiting

the coil ???

only the temperature entering the coil, T1.

pumpmanplee

## RE: BATCH HEATING OF TANK USING INTERNAL COIL - calculate surface area of internal coil

Good luck,

Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.