Water is heated in 3 steps:
SOLAR POND: Initially water is pre-heated using the solar pond. In the solar pond the salt is mixed along with water due to which the hot water remains at the bottom and heat is extracted using a heat exchanger.
GLASS TUBES: the temperature of water is further increased using the glass tubes where greenhouse phenomenon takes place.
SOLAR CONCENTRATOR: The water is converted to steam by using a solar concentrator boiler in which optical tracker is also used to maximize the efficiency.
parabolic dish will be constructed out of fiberglass, which is chosen because
of its ability to form to any mold. The entire concentrator system is limited
in size because of the parabolic dish. The largest mold that is practical to
make in house is limited to a 1.2 m (4 ft.) x 2.4 m (8 ft.) plywood sheet.
reflective material to be used for the project is a silver polymer film. This film
reflects 94% of the solar spectrum and lasts 10 years in an outdoor environment.
This particular material is chosen for its extremely high reflectivity and flexibility
of application. The film has an adhesive backing that can be applied easily to
horizontal mount system has two axes of movement that independently track the
altitude and azimuth motion of the Sun.
receiver for this system acts as an absorber, boiler, and heat storage unit. A
cavity type absorber is used due to its high absorption efficiency and low heat
loss. Surrounding the absorber inside the receiver is sodium nitrate which acts
as a heat transfer and storage media and copper tubing was coiled through it.
The working fluid is pumped through the tubing where heat is transferred to the
of the parabolic dish was accomplished by two satellite dish linear actuators.
The steam is used to rotate the turbine which is connected to the pump and hence water is pumped in the field. :)
Pump: 1 hp pump will be used that would easily irrigate 1 hectare field if used for 2-3 hrs a day.
Basics of solar pond: http://www.youtube.com/watch?v=SqWjhkXVRzM
solar concentrator tracking: http://www.youtube.com/watch?v=9DobOOi7-Jk
High temperature and pressure is attained due to:
1.A high CR is kept to increase the absorber temperature.
2.A 14 sq m concentrator concentrates lot of sunlight.
3. Pre-heating by solar pond and flat plate absorber.
Very less sunlight is required throughout the day due to:
1. Heat is not directly transferred to water but to a fluid which stores energy in itself it has a high melting point so this stores energy is used during night and during unavailibilty of sunlight.
2. A 14 sq m dish produces electricity more than double the need so if the sunlight just remain for half the day it would do the job.
High efficiency due to:
1.Pre-heating by solar pond.
2.Cavity absorber rather than flat plate absorber
3.Inclination of cavity absorber is kept vertical to minimise losses due to convection.
4.A good reflecting surface:silver polymer film which reflects 94% of the solar spectrum and lasts 10 years in an outdoor environment