Development of “Low-tech” Solar Thermal Water Pumps for Use in Developing Countries

Abstract

Solar water pumps, based on electro-mechanical pumps powered by PV arrays, are commonly used and commercially available. However, one of the difficulties for their wider application in developing countries, where there is a high average insolation, is their relatively excessive cost. This arises mainly due to the high cost of the PV elements. Hence, this paper describes some developmental work and results of experimental tests on “low-tech” solar thermal water pumps which were built on the basis of Stirling engines with fluid pistons coupled to flat-plate solar collectors. Temperatures and pressures in the cycle are comparatively low, thus cheap design materials, such as glass and plastic, and a simple technology, available in the majority of mechanical workshops, can be used for their manufacture and consequently reduce their cost. Several design modifications of the above solar thermal water pumps have been developed and tested. The results obtained demonstrate that existing installations can be effectively applied for water pumping with a dynamic head which varies between 2-5 m. Furthermore, data from experimental tests shows that the pulsating motion of water in channels of the flat-plate solar collectors increases the collector’s efficiency by approximately 8-10%, which is a considerable advantage when a pump is used as part of a house solar heating system.

A variant of the Fluidyne: the liquid piston ERICSSON engine

“…Some Stirling engines use both liquid and solid pistons. The first solid-liquid hybrid piston Stirling engine was developed by Orda [23] to improve the stability of Fluidyne operation by using a spring-loaded piston-actuator. Its thermal efficiency varies between 0.2 and 0.5%.…”

“…Its thermal efficiency varies between 0.2 and 0.5%. Since then, many studies have been carried out to develop these hybrid piston Stirling machines [24][25] and some of which are powered by solar energy [23][24][25].…”

A novel solar-powered active low temperature differential Stirling pump

“…Bumataria and Patel [25] presented a review work on development of the solar powered Stirling engines that can be employed as a water pump at rural regions. Orda and Mahkamov [26] developed a passive LTD solar thermal water pumps for use in developing countries using Stirling engines and flat plate solar collectors. The experimental works revealed the feasibility of pumping water at low temperature difference.…”

Dynamic Coupled Electrical and Thermal Model for PV-T Solar Energy Collectors

“…The solar energies (Electrical and Thermal) are more and more used to exploit renewable energies. The hybrid photo voltaic and thermal (PV/T) systems are used in several applications like heating systems [1], [2], [3], water heating [4], [5] and the water pumping [6], [7]. Integrated photo-voltaic and thermal systems have proved to have better performance and efficiency [8].…”