水车发电计算

  RIVER TURBINES

The power available from the river

Most of the principals of this type of turbine are based upon wind turbines, as they work in asimilar way. The power available (Pa) in watts can be worked out using the following formula.

Pa= ? x Cpxρx A x v3

 A = area in metres squared (m2)

ρ= density of water (1000 kg/m3)

V = velocity of water (m/s)

Cp= the power coefficient = 16/27 = 0.592 (theoretical maximum power available）

The theoretical maximum power available from the river is expressed by the equation aboveusing a power coefficient of 0.592 or 59% efficiency. But a small-scale river turbine has itsown losses which will reduce the power coefficient to around 0.25.The significant aspect to the equation is that the power increases in a cubed relationship tothe velocity of the flow of water past the turbine. Therefore it is important to find the best flowto get the best power output.