Chemical Engineering - Heat Transfer - Discussion

Discussion Forum : Heat Transfer - Section 1 (Q.No. 21)
21.
Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately
32
37
45
50
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
36 comments Page 4 of 4.

SATHISH said:   5 years ago
For co-current flow answer is 32.

And for Countercurrent flow answer is 37.

Maha said:   4 years ago
For counter current (as mentioned in statement):
LMTD = 37.

MADHAN said:   4 years ago
For counter current flow,

∇(t1) = hot water inlet (-) cold water outlet.
∇(t2) = hot water outlet (-) cold water inlet.
(1)

Mehtab Ali said:   3 years ago
For counter-current flow ---> LMTD = 36.66 ~ 37.
For parallel flow ----> LMTD = 31.82 ~ 32.
(4)

Anon said:   2 years ago
how did u guys get 35.75 deg C as outlet temp of oil?
(1)

Anuj said:   1 year ago
@All.

We have to find the cold coil outlet temp with the help of the given data and assume that Q rejected by the hot fluid is equal to the heat gained by the cold fluid, then we will get 36.8.

So, the right answer will be 37 °C for counter-current flow.
(1)


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