1. The document describes an experiment to determine the heat transfer coefficients in an agitated vessel with a helical coil. Various parameters that affect heat transfer such as agitator speed and diameter, coil diameter, and liquid flow rate are kept constant. 2. A correlation is provided to calculate the heat transfer coefficient between the fluid and coil surface based on the experimental parameters. 3. The experimental setup involves a vessel with a central agitator coupled to a motor. Thermometers measure inlet and outlet fluid temperatures to the coil. Heat is supplied to the vessel fluid and cold water is circulated through the coil. 4. Observations of temperatures are recorded at different coil flow rates. Calculations are

1. EXPERIMENT NO:
HEAT TRANSFER IN AGITATED VESSEL
AIM:-
To determine the overall and individual heat transfer coefficients in an agitated vessel
[Constant RPM].
INTRODUCTION:-
Agitated vessels are widely used in chemical industries to carry out heat and mass
transfer operations as well as a reactors, crystallizer and mixer. When the chemical reaction
takes place in an agitated vessel, the heat is either to be given or taken out for carrying out the
reaction. This is done by fixing either helical coil inside the vessel or jacket from outside the
vessel. Hence it is always desired to know the heat transfer characteristics of an agitated vessel.
THEORY:-
The heat transfer characteristics in an agitated vessel are functions of –
1. Speed of the agitator
2. Depth of the agitator
3. Diameter of the agitator
4. Helix diameter
5. Coil tube diameter, etc
We keep all the above variables constant for given equipment then the flow rate of the
liquid through the coiled tube or jacket will affect the heat transfer rate.
The correlation for heat transfer to fluids in the vessel with mechanical agitation heated or
cooled by submerged coil is for constant RPM is given by
hc Dc / k = 0.87 [ Da
2 N ρ / µ]1/3 [ Cp µ/ k]0.1
hc = Heat transfer coefficient between fluid and coil surface in (kcal/(hr)(m2
)(o
C))
k = Thermal conductivity of water in vessel in Kcal/(hr)(m2
)(0
C)
Da = Agitator diameter

2. Dc= Coil diameter in m
N = Speed of an agitator in revolution/s
µ = Viscosity of the liquid in the vessel at the mean temperature in kg/ (m)(hr)
CP = Specific heat of the liquid in the vessel in Kcal/ (Kg) (0
C)
ρ = Density of the liquid inside the vessel in Kg/m3
EXPERIMENTAL SETUP:-
Standard vessel configuration recommends the following ratios:-
1. Agitator diameter, Da = (1/3)(tank dia., DT)
2. Height of agitator from bottom of vessel-
3. Height of liquid in vessel, HL = DT
1. The agitator is fixed at the centre, coupled with motor.
2. The thermometers are provided to note the temperatures of the fluid entering and
leaving the setup.
3. The heating of the fluid inside the vessel is controlled by using either one or teo water
heaters.
PROCEDURE:-
1. Take the fluid (water) inside the vessel.
2. Keep the heater on.
3. Admit the cold water in the helical coil at fixed rate.
4. Maintain the temperature of the vessel fluid at the desired level.
5. At the steady state, note down the inlet and outlet temperature of the fluid flowing in
the helical coil, the vessel liquid temperature.
6. Change the flowrate of cold fluid passing through the coil.
7. Repeat the same procedure for the different flowrates of cold fluid passing through the
coil.

3. OBSERVATIONS:-
1. No of turns = 25
2. Helix Diameter = 39cm
3. Length = 6.6 m
4. Vessel Diameter = 41cm
5. I.D. of coil = 1.8cm
6. O.D. of coil = 1.5cm
7. RPM = 160
OBSERVATION TABLE:-
Sr.
No.
Cold Water
flow rate
mC(gm/sec)
Temperature of the
cooling fluid
Vessel
liquid
temperature
(TV
0C)
Speed of
agitator
N rpm
Remarks
Inlet
temp.
(Ti0C)
Outlet
temp.
(To
0C)
1.
2.
3.
4.
5.
CALCULATIONS:-
1. Heat transfer rate:-
Qc = mc Cpc ΔT
Where, Qc = Heat gained by the cold fluid in (Kcal/ hr)
mc = Mass flow rate of cold fluid in (Kg/ hr)
Cpc = Heat capacity of the cold fluid in (Kcal/ (kg) (0
C))

4. ΔT = Rise in cold fluid temperature = (Tc2- Tc1) 0
C
2. Overall Heat Transfer Coefficient:-
We Know that,
Q = Uo Ao ΔTm
ΔTlm = [(Th – Tc1) - (Th – Tc2) ] / ln [(Th – Tc1) / (Th – Tc2)]
Ao = Outside area of the coiled tube in m2
.= π2
DH n do
Here-
DH = Helix diameter in m.
n = Number of turns
do = Coiled tube inside diameter in m.
6. Inside film heat transfer coefficient (hi):-
The inside film heat transfer coefficient for the coil will be greater than for the straight
pipe because of the increased turbulence owing to the circulatory path. Hence hi can be
calculated as
hi = 0.023 (Re)0.8
(pr)0.4
[1 + 3.5 (Di/Dc)] Di/k
where, Di is inside diameter of coil and Dc is diameter of helix
We know the relationship between film and overall heat transfer coefficients. Hence outside
film heat transfer coefficient can be calculated as :
1/ho = 1/U – do/di hi – xw/k
ho =

5. RESULT:-
Sr. No. hi
W/m2K
ho
W/m2K
01
02
03
04
05