Answer: it refers to the ratio of effective power and shaft power of the pump. ETA =Pe/P
The power of the pump usually refers to the input power, that is, the power transmitted by the prime mover to the pump shaft, so it is also called the shaft power, which is represented by P.
The effective power is the product of the lift, mass flow and acceleration of gravity.
PE = ρ g QH w or PE = γ QH / 1000 (kw)
ρ: Density of liquid delivered by pump (kg / m3)
γ: Gravity of pump liquid γ = ρ g (n / m3)
g: Acceleration of gravity (M / s)
Mass flow QM = ρ Q T / h or kg / S
1、Calculation formula of shaft power of centrifugal pump
Flow × lift × 9.81 × medium specific gravity ÷ 3600 ÷ pump efficiency
Flow unit: m3 / h,
Head unit: M
P=2.73HQ/ ETA,
Where h is the head, unit m, q is the flow, unit m3 / h, η is the efficiency of the pump. P is the shaft power, unit kW. That is to say, the shaft power of the pump P = ρ GQH / 1000 η (kw), where ρ = 1000kg / m3, g = 9.8
The unit of specific gravity is kg / m3, the unit of flow is m3 / h, the unit of lift is m, 1kg = 9.8N
Then p = specific gravity * flow * lift * 9.8n/kg
=Kg / m3 * m3 / h * m * 9.8n/kg
=9.8N * m / 3600s
=Newton * m / 367 seconds
Watt /367
The derivation above is the origin of the unit. The formula above is the calculation of water power. The shaft power is divided by the efficiency
Set shaft power as Ne, motor power as P, K as coefficient (reciprocal of efficiency)
Motor power P = Ne * k (K has different values at Ne, see the table below)
Ne≤22 K=1.25
22
55
2、Calculation formula of shaft power of slurry pump
Traffic Q M3/H
Head h m H2O
Efficiency n%
Slurry density a kg / m3
Shaft power n kw
N=H*Q*A*g/(n*3600)
The transmission efficiency and safety factor should also be considered for the motor power. 1 for general direct connection, 0.96 for belt and 1.2 for safety factor
3、Pump efficiency and its calculation formula
It refers to the ratio of the effective power of the pump to the shaft power. ETA =Pe/P
The power of the pump usually refers to the input power, that is, the power transmitted by the prime mover to the pump shaft, so it is also called the shaft power, which is represented by P.
The effective power is the product of the lift, mass flow and acceleration of gravity.
PE = ρ g QH (W) or PE = γ QH / 1000 (kw)
ρ: Density of liquid delivered by pump (kg / m3)
γ: Gravity of pump liquid γ = ρ g (n / m3)
g: Acceleration of gravity (M / s)
Mass flow QM = ρ Q (T / h or kg / s)
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