A single acting reciprocating pump, running at 40 rpm, has piston of 20 cm diameter and stroke length of 40 cm. The suction and delivery heads are 5 m and 20 m, respectively. Assuming overall pump efficiency as 80 %, the power requirement of the pump, in kW, is __________. (Rounded off to 2 decimal places)
Official Answer Key:
2.45 to 2.75
Step-by-Step Solution & Explanation
Step 1 — theoretical discharge of a single-acting reciprocating pump. One delivery stroke per revolution:
Q = A × L × N/60
A = (π/4)(0.20)² = 0.031416 m²
Q = 0.031416 × 0.40 × 40/60 = 0.0083776 m³·s⁻¹
Step 2 — total head:
H = suction head + delivery head = 5 + 20 = 25 m
Step 3 — power required:
P = ρgQH/η
= (1000 × 9.81 × 0.0083776 × 25)/0.80
= 2054.6/0.80
= 2568 W = 2.57 kW
SECTION 6: AGRICULTURAL PROCESS ENGINEERING
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