4.31 Initially, an insulated rigid tank contains 3.12 kg of water at 270 celsius

ID: 1860198 • Letter: 4

Question

4.31 Initially, an insulated rigid tank contains 3.12 kg of water at 270 celsius and 1 MPa.

A heater in the wall of the tank maintains the wall temperature at 600 celsius.

After a period of time, the pressure in the tamk rises to 1.5 MPa.

Determine the final temperature Celsius of the water in the tank.

Use specific heats from tables for water.

Answer: 524.37

PLEASE SHOW ALL WORK INTERPOLATION AND

HOW TO GET ALL NUMBERS NEEDED thankyou so much

Please use these tables and state which ones used thanks much

State 1

at T = 278.5 the saturated pressure is 6378KPa but given pressure is 1000KPa so the state is superheated

At 1000KPa from properties tables

T = 250 s =6.9246 and

T = 300 s = 7.1228

Now we need to find

at T = 278.5 what is s

By interpolating(equating the slopes)

(s-7.1228)/(7.1228-6.9246 ) = (278.5-300 )/(300 -250)

s = 7.1228 + (7.1228-6.9246 ) (278.5-300 )/50

s = 7.0376

At T =600 and P =1500 KPa the state is superheated

At T = 600 from properties tables

P =1400 Kpa s = 7.8710

P =1600 KPa s = 7.8080

P = 1500Kpa s = ?

s = 7.8395

Total entropy generation

S = m*(s2 -s1)

S = 2.31*(7.8395-7.0376) = 1.8524 KJ/K

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