Windpumps

Introduction

The design of the Auroville Multiblade Windmill has evolved from practical experience gained in operational use over the last 33 years. The result is a reliable and efficient device, which requires minimum maintenance.

In support of these claims, it is interesting to note that the Auroville Windpump was listed and described in the European Community Joule Project JOU2 CT93 0421: “Power for the World A common concept” as an excellent example of a Renewable Energy Application. A cost comparison done by Halcrow Gilbert Associates Ltd., UK, for the Government of the Netherlands, also states that the Auroville windpump delivers the lowest cost per water unit, compared with other windpumping systems, PV pumps or diesel pumps.

Description

The Auroville Windpumps are horizontal axis, multi-directional metal blade windmills with rotor diameter of 5.7metres or 4.5metres. The windmills are mounted on free standing tripod towers made out of tubes available in different heights from 9 metres to 23 metres.

How the matching valve works:
The matching valve is a float valve built into the piston of the pump which replaces the disc valve of the standard piston pump.

In low wind the float valve remains open at the beginning of the upstroke, and the rotor can start turning without any load; it doesn’t even have to lift the pump rods, as their weight is counterbalanced by a counterweight fixed in the rotor.

As the velocity of the pump piston increases, the valve closes as soon as the calculated critical piston velocity is exceeded and pumping starts. In very low windspeed the float valve remains permanently open; the rotor turns without lifting any water. Once the average windspeed exceeds 1.5 m/s the rotor speed is sufficient and pumping starts.

With this low cut-in windspeed the pump has a volumetric efficiency of 0.51. With a progressively increasing rotor speed the volumetric efficiency also increases until it reaches 0.9 at a windspeed of 3.5 m/s. At windspeeds above 3.5 m/s the float valve functions like an ordinary disc valve in a standard piston pump.

Specification

Range of application:
The windmill can be used for pumping water from deep borewells – max. 100m depth with the AV55 and 70 m depth with the AV45 – as well as for low lift high volume output from shallow wells.

Bearings:

• Rotor shaft : Two sealed roller bearings
• Connecting rod : top is a sealed roller bearing; bottom is a teflon bush bearing (maintenance free)
• Cross head : Sleeve bearing (low maintenance)
• Jaw bearing : Teflon / nylon (low maintenance)

Pumps:
Single acting piston pumps.

• Cylinder bore diameters : 64mm / 82mm / 108mm / 130mm / 160mm
• Cylinder materials : stainless steel
• Cup washer : synthetic rubber
• Foot valve : synthetic material
• Piston valve seat : stainless steel
• Pump rods : round steel rod, diameter 16mm

Foundations:
The tower foundations and the delivery pipe clamp anchoring have to be executed according to our layout drawings.

• Tower foundation : 3×0.3m³ concrete
• Delivery pipe anchor : 1×0.2m³ concrete

Benefits

A cost-comparison of different pumping methods was published in the report “WINDPUMPS IN DEVELOPING COUNTRIES” by Halcrow Gilbert Associates Ltd., prepared for the Government of the Netherlands in 1993. This cost comparison shows that the Auroville Windpump delivers the lowest cost per water unit, compared with other alternative pumping systems.

Range of products

Auroville Multi-blade windmill models:

• AV45 – Windpump complete with rotor dia 4.5m, head, tail and turntable
• AV55 – Windpump complete with rotor dia 5.7m, head, tail and turntable

Tripot tower made out of GI – Tube

Single stroke piston pump for maximum stroke length of 230mm

Steel pump rod: Dia 16mm, including coupling 1 length 6m.