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Hybrid Solar Chimney with Salt Water Desalination and Power Generation


Published on Dec 27, 2018

Abstract

Solar technology is the novel technology which uses the natural sunlight to produce electricity. It uses the combination of three simple technologies that is turbine, vertical chimney of some longer height and glass roof collector for absorbing the sun radiations. By proper utilization of this technology the electricity can be generated in abidance and continuously for twenty four hours throughout the year in county like India where there is sunlight almost for nine months in the major part of the country. Much advancement has taken place in this technology for last three decades but the full utilization of this technology has not taken place because of various aspects. This paper presents the critical review of this important technology in the form of the advancements and developments taken place in various parts of the world and analyzes its important aspects

Introduction

The future of this earth and mankind substantially depends on our ability to slow down the population increase in the “Third World” by civilized means. The key is to increase the standard of living, to overcome the inhumane poverty and deprivation. Development requires mechanization and energy. Energy consumption increases proportionally to the gross national product or prosperity while simultaneously the population growth will decrease exponentially. Many developing countries possess hardly any energy sources and their population doubles every 15- 30 years. The result of which are commonly known that is civil wars and fundamentalism. If these developing countries are provided with only a humane and viable minimum of energy the global energy consumption will drastically increase. The sun is the only source which can supply such an enormous amount of energy without an ecological breakdown and without safety hazards and without a rapid depletion of natural resources at the expenses of future generations. Solar chimneys are such devices which can generate energy up to large extent by use of the simple device that is greenhouse collector, Vertical chimney and turbine and produce electricity continuously at minimum cost. It is very necessary to adopt this technology in every part of the world like other conventional sources which we are using regularly.

Solar Chimney

The solar chimney power plant combines three familiar components: A solar collector, a solar chimney and power conversion unit (Jorg Schlaich & Wolfgang Schiel, 2000) which include one or several turbine generators. The turbine is driven by air flow produced by buoyancy resulting from greenhouse effect inside the collector (Fig.1). The main function of solar chimney system is to convert solar energy into electrical energy. In the collector, the solar energy will transform into heat energy. The chimney converts the generated heat energy into kinetic energy, which will be transformed into electric energy by using a combination of a wind turbine and a generator. The collector in solar chimney system consists of support matrix, column structure and transparent roof.

A large air collector is formed when a transparent glass or plastic roof supported above the ground by column structure and support matrix is stretched out horizontally many meters. The height of the roof slowly increases along a radius from the periphery to the center to guide inward airflow with minimum friction losses. This glass or plastic roof allows the transmission of the shorter wavelength solar radiation but blocks the longer wave length radiation emitted by the ground. As a result, the ground under the roof heats up which in turn heats the air flowing radially above it. The soil surface under the collector cover works as a storage medium, which saves a part of the incoming solar radiation during a day and releases it later during the night. This mechanism is capable of providing a continuous supply of power all year round.

solar chimney

The chimney situated in the collector center is the actual thermal engine of the solar chimney power plant. The up thrust of the air heated in the collector is proportional to the rise in air temperature flowing in the collector and its volumetric flow rate. Suitable turbines located at the base of chimney convert kinetic energy of the up flowing air inside chimney to mechanical power in the form of rotational energy. The typical solar chimney turbine is of the axial flow type. The principle of operation of these turbines is similar to the turbo generators used in hydroelectric power stations, where the static pressure is converted into mechanical work. The power output achieved is proportional to the product of the volume flow rate and the pressure drop across the turbine. The air flow through the turbine can be regulated by varying the turbine blades pitch angle. This mechanical energy can be converted into electric energy by coupling the turbine to the generator. Solar chimney does not necessarily need direct sunlight. They can exploit a component of the diffused radiation when the sky is cloudy. The lack of system dependence on the natural occurrence of wind, which is intermittent, makes it a very attractive development.

Objectives:

(i) Fabrication of Solar energy driven solar chimney desalination system experimental setup with low cost vapour condensing system and electric power generation with diffuser

(ii) Analysis of production of fresh water from desalination system with and without waste heat recovery

(iii) Analysis of power generation with and without desalination system

(iv) Analysis of power generation with and without thermal storage and without desalination

Methodology

Fabrication of solar chimney with desalination system

Specifications:

 Chimney height= 3 m

 Chimney diameter = 20 cm (till 1 m height and diverges to 24 cm)

 Collector diameter = 5 m

 Height of Collector = 6 cm

 Height of the circumferential break = 1 m

 Diameter of heat storage/ waste heat recovery pipe = 1.25 cm

 Number of trays= 6

 Size of the tray= 1m X 1.2m

Materials used:

 Chimney pipe: G.I Sheet

Absorber plate: G.I Sheet

Collecting area cover: Transparent Plastic sheet

As the fabrication drawing the setup will be done.

Measurement of Temperature and Humidity

A circuit board with four Temperature-humidity sensors is set. At the entry of collecting area, before the turbine, before opening for condensation and exit of the chimney.

Results and Discussion

Desalination of sea water with waste heat recovery system and power generation.

Water is poured to the trays, hot water is passed through the pipes and readings of Temperature humidity sensors taken.Velocity of air at entry of collecting area, Before turbine and exit of the chimney has been taken.

Desalination of sea water without waste heat recovery system.

Water is poured to the trays and readings of Temperature humidity sensors taken. Velocity of air at entry of collecting area, before turbine and exit of the chimney has been taken.

Power generation with thermal storage.

Absorber plate with black paint is set in the collecting area to absorb the heat from sunlight. Air present in the collecting area get heated up and because of the density Difference it starts to move upwards through the chimney. Air will pass through the turbine to generate the power. Air velocity at different rate is measured.

Power generation without thermal storage.

Air is passed through the collecting area and gets heated up. That air is pass through the turbine to generate electricity.

Solar Chimney

Scope for Future Work:

Generation of electricity using solar energy is a feasible alternative for power generation over conventional power plants like thermal and hydraulic power plants. It is an ideal technology that can be adopted in the countries like India that have sunshine almost nine months in the year and lot of free space available for setting large amount of power plants. The only problem is awareness and initiative required and also some sound technical feasibility is required so that this technology can be adopted with ease. In this paper a detail literature review of this technology was performed. The review gives basic principle and operation of this system. It also gives the present status of this technology and various feature scope of this technology. This paper shows that lot of numerical and experimental studies are carried out by keeping Manzanares power plant as reference. It is concluded that such system should be constructed in a very large way to generate large amount of electricity. CFD methods are adopted by many researchers because of high constructional cost of these power plants.

Conclusions

 With absorber plate the temperature increases inside the collecting area and that increases the velocity of air passing through the turbine.

 Desalination is done by using sea water. As the temperature increases it increases the evaporation rate increases which intern increases the condensation rate.

References

[1] Jorg Schlaich & Wolfgang Schiel, Solar Chimneys, Encyclopedia of Physical Science and Technology Third Edition, 2000.

[2] Reid Smith and Lisa Cohn, the 27 European Photovoltaic Solar energy conference and exhibition Messi Frankfurt Germany, 2012

[3] A.A. El-Haroun, Performance Evaluation of Solar Chimney Power Plants in Egypt, Int. J. Pure Appl. Sci. Techno., 13(2), 2012, 49-59.

[4] G.M.Ngala, A.T. Sulaiman, I. Garba, Review of Solar Chimney Power Technology and Its Potentials in Semi-Arid region of Nigeria, International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.3, Issue.3,2013 283-1289

Project Done By Mr. Mohammed Zunaid, Ms. Ashwini S, Mr. Kiran C. Hiremath, Mr. Hanumantha K. Kalasadavar





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