Air enters a counter flow HE at 70°C and leaves at 40°C.

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Air enters a counter flow HE at 70°C and leaves at 40°C. Water enters at 30°C and leaves at 50°C, the LMTD in degree C is

1. 5.65
2. 14.43
3. 19.52
4. 20.17

Correct Option: B

∴ ∆T₁ = 70 – 50 = 20°C, ∆T₂ = 40 – 30 = 10°C

LMTD =	∆T₁ ∆T₂
	log		∆T₁
			∆T₂

=	20 - 10				= 14.43
	log		20
			10