Project ForgeHeat Transfer
Heat Exchangers
GATE 2010
Hard
For the same heat exchanger (hot oil 150→110°C, cold fluid 30°C in, equal heat capacity rates, Q=2kW), under counter-current flow conditions, the overall heat transfer resistance (1/UA) is
- A0.4 °C/W
- 0.04 °C/W
- C0.36 °C/W
- D0.036 °C/W
Explanation
With equal heat capacity rates, counter-current flow gives a CONSTANT temperature difference throughout: ΔT=150−70=80°C=110−30=80°C. LMTD=80°C exactly. 1/UA=80/2000=0.04 °C/W.
Source: GATE CH 2010 (2010)
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