The Water Buffalo: Design of a Portable Bicycle Powered Irrigation Pump for Small-Scale African Farmers

Abe McKay
2018 Figshare  
This thesis reports on the development a low cost and mass-producible bicycle powered irrigation pump for small-scale (100–1,000 m2 plot) African farmers. The pump is intended to be made and distributed by World Bicycle Relief's Buffalo Bikes program. This project's process is divided into three parts: an investigation into the user needs, quantitative testing of a prototype pump's power and efficiency, and the redesign of the pump for manufacturing. In order to clarify the user needs, I
more » ... ser needs, I conducted in-depth interviews and informal demonstrations with small-scale farmers in Kenya. I learned of additional user requirements; for example, that the pump must be usable by children. I also learned of critical problems with the early design; for example, that air leaks on the suction side of the pump will hobble its performance. Though imperfect, the limited success of the trials verified the viability of a bicycle irrigation pump in the target market. To quantify the effectiveness of a centrifugal bicycle powered pump, I measured the pump's water flow at various input power levels and outlet heights (vertical heads). The efficiency of the pump system (η ≈ 55%) approached the claimed manufacturer's maximum efficiency of η ≈ 66%. I then compared the bicycle pump to two other human powered pumps, both of which use a treadle pumping style. The bicycle system pumps water at similar or possibly higher flows than the tested treadle pumps. Friction calculations additionally revealed that at fast flow rates of 1 liter per second (16 gallons per minute), hoses with a 1 inch diameter (25.4 mm) have significant friction losses, while 1.5 inch (38.1 mm) hoses have negligible friction losses. Based on the interviews and efficiency tests, I redesigned the pump and gearbox to be made of plastic and to address the main issues identified in the field. The pump-to-hose attachments are designed to reduce air leaks, reduce tipping, and simplify the pump's setup. The form of the gearbox is designed without overhangs so that it can be manu [...]
doi:10.6084/m9.figshare.6378401 fatcat:eoxz7fbe2bfpparcj7winrlioq