Developement of Solar -Thermal Powered Stirling Engine based Water Pumping System for Agricultural Applications

Abstract

A number of attempts have been made by scientists to utilize solar energy for irrigation water pumping. It is mainly a problem of conversion of heat energy available from the sun to mechanical energy. Some ingenious methods have been devised to utilize the available energy at low temperatures. An exhaustive literature review was done, in order to nd out the results of the research work conducted so far in this area. Certain research articles in the allied areas were found, however work related to experimental study of gamma type stirling engine in solar pumping system is limited. The present study involves a modelling of solar stirling engine based water pumping system, material selection of various components such as base, piston, power piston, bellows pump, radiator and explains the working of solar water pumping system. In this research, a gamma-type, low-temperature di erential (LTD) solar Stirling engine with two cylinders was modeled, constructed and primarily tested. A at-plate solar collector was employed as an in-built heat source, thus the system design was work with minimum temperature di erence of 40 oC. The principles of thermodynamics as well as Schmidt and West theory were adapted to use for modeling the engine. For modelling the solar pump system, solidworks 2011 was used. The mean collector temperature of 78 oC and sink temperature of 34 oC. Though stirling engine e ciency was measured around 56.41%. The corresponding theoretical e ciency of the whole pumping system for the mentioned designed parameters was calculated to be 4% with regenerator. Proposed engine dimensions are as follows: power piston stroke 104 mm, power piston diameter 110 mm, displacer stroke 204 mm and the displacer area is 1.9 m2. Finally, the engine was tested. The results indicated that at mean collector temperature, the engine produced a maximum power of 5 Watt. The mean engine speed was about 30 rpm and e ciency was around 2% at solar radiation intensity of 500 W=m2 . Solar pump was tested during winter and summer weather. It was found that discharge was continuously vary with available solar radiation. During winter condition solar radiation was measured around 600 W=m2 and pump operate around 4 to 5 hours per day. At the same time during summer condition solar radiation was measured around 900 W=m2 and pump operate around 6 to 7 hours per day. The discharge was around 400- 450 liter=hour at constant head 4.5 meter. The initial cost of entire system was found around 2.5 lacs though it was preferable at remote area where electricity supply was not available or Fluctuate, this system is more preferable for irrigation purpose.