50 litter of water is heated with Electric Heater at Atmospheric Pressure from a temperature of 25C and convert into 100C Steam.
50 litter of water is heated with
Electric Heater at Atmospheric Pressure from a temperature of 25oC
and convert into 100oC Steam. How much heat and what capacity of Electric heater
is required to do so. The evaporation will be done within 10 hours (10 x 3600 = 36000 seconds).
SOLUTION
Water to be evaporate = 50 kgs or
50 liters
Feed Water Temp = 25OC
Water Boiling Temp = 100OC
Steam Tem = 100OC
Steam Pressure = Atmospheric
Pressure
Heat require to rise the temp
from 25OC to 100OC of 1000 gm water
Q1 = m C (T2 – T1)
Q1 = 1000 x 1 x (100 –
25)
Q1 = 1000 x 1 x 75
Q1 = 75 x 103 Cal
Now heat require to convert 1000
gm of water at 100OC to 100OC Steam at Atmospheric
pressure
Q2 = mL
Q2 = 1000 x 540
Q2 = 5.4 x 105 Cal
Total Heat required to convert
1000 gm (1Kg) of water at 25OC to 100OC Steam.
Q = Q1 + Q2
Q = 75 x 103 + 5.4 x
105
Q = 615 x 103 Cal
Q = 615 x 103 x 4.184 = 2.57 x 106
Joule (1cal = 4.184 J)
Q50kg = 2.57 x 106
Joule x 50 = 128.5 x 106 Joule
Now calculation for Electric
Heater required capacity
We know that, P = V x I
Also we know, V = I x R
And, H = I2 x R x T
So, Q = P x T
Where,
P = Power in watt
V = Voltage in volt
I = Current in amp
R = Resistance in omh
T = Time in seconds
Q = Heat in joules
Now put the value in (Q = P x T)
this equation
128.5 x 106 = P x 10 x
3600
P = 128.5 x 106/36000
P = 3569.44 W
If Electric Heater efficiency is
about 80% then
Required Electric Heater Power =
3569.44/80%
Required Electric Heater Power =4461.8
W
Therefore we use 4500 W rating
Electric Heater to evaporate the water within 10 hours.
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