Project ForgeA constant head pump transfers a liquid from a tank maintained at 20psi to a reactor operating at 100psi, through a heat exchanger and a control valve. At design conditions, the flow rate is 1000 litres/min, with pressure drop 40psi across the heat exchanger and 20psi across the control valve. The pressure drop across the heat exchanger varies as the square of the flow rate. If the flow is reduced to 500 litres/min, then the pressure drop across the control valve is
- A30 psi
- 50 psi
- C80 psi
- D150 psi
Explanation
Constant head pump ⟹ total available ΔP=140psi=(100−20)+40+20 is fixed regardless of flow. New HX drop=40×(500/1000)²=10psi. New valve drop=140−80(fixed reactor-tank ΔP)−10=50psi.
Source: GATE CH 2010 (2010)
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