An Experimental Investigation of Overshot Waterwheel in Very Low Head Water Resources for Pico Hydro

Abstract

Waterwheels are considered a low-cost and simple alternative method for rural electrification and this paper aims to investigate the performance of a non-complex geometrical design of overshot waterwheel in a pico hydro system. The waterwheel and the hydro system have been assessed at very low water heads condition at 1.5 m water and 5 L/s flow rate using a water test rig. According to the experimental results, the proposed waterwheel manages to achieve significant rotational speed, mechanical torque, and efficiency. The rotational speed has produced more than 130 rpm with mechanical torque reaching up to 1.2 Nm. Analytically, the turbine with four bottles per blade has an efficiency of 32 %. This is higher than the efficiency of three bottles per blade at 24 %. The results have also indicated that the overall performance of overshot water wheels with four bottles blade is higher than the three bottles per blade. Furthermore, certain specific values of water head and flow rate have been found out to be able to obtain the optimum efficiency. At the same time, the values of water head and water flow rate have been also found to be proportional with the value of the mechanical torque produced. Finally, the ability of the proposed system to produce a considerable output for power generation has showed that it is potentially viable to be used at the actual field.