Solar Hybrid Chimney | Mechanical Project pdf Report Download

ABSTRACT
Solar thermal hybrid chimney is a new method for producing electric power from a solar-wind hybrid system. It combines three old and proven technologies: the chimney effect, the greenhouse effect, and the wind turbine. Energy from sunlight is converted to heat by a large
solar collector. The collector is a transparent membrane suspended several meters off the ground, which can be made of glass or a strong transparent polymer. Sunlight penetrates this membrane, and the solar radiation is converted to heat upon hitting the ground. The air underneath the membrane quickly increases in temperature due to the greenhouse effect and flows towards the chimney, which, through the stack effect, becomes the lowest point of pressure in the system. This continuous airflow spins a turbine located at the base of the chimney. Inside the chimney wind turbines convert the wind’s energy into electricity. This method can also be useful during night time. The project work requires a significant area of land. A small-scale solar updraft tower may be an attractive option for remote regions in developing countries.

Solar thermal power generation technologies:

Some of these technologies are as following:

Concentrating solar collectors.
Power tower system.
Parabolic dish system.
Solar hybrid chimney.

Introduction To Solar Hybrid Chimney:
A wide range of existing power technologies can make use of the solar energy reaching Earth. Basically, all those ways can be divided into two basic categories: transformed for use elsewhere or utilized directly – direct – and involving more than one transformation to reach a usable form – indirect. The Solar Chimney Power Plant (SCPP) is part of the solar thermal group of indirect solar conversion technologies. More specifically, a natural phenomenon concerning the utilization of the thermal solar energy involves the earth surface heating and consequently the adjacent air heating by the sun light. This warm air expands causing an upward buoyancy force promoting the flow of air that composes the earth atmosphere. The amount of energy available due to the upward buoyancy force associated with the planet revolution is so vast that can generate catastrophic tropical cyclones with disastrous consequences.

Modern Development In Solar Hybrid Chimney:
Detailed theoretical preliminary research and a wide range of wind tunnel experiments led to the establishment of an experimental plant with a peak output of 50 kW on a site made available by the Spanish utility Union Electrica Fenosa in Manzanares (about 150 km south of Madrid) in 1981/82, with funds provided by the German Ministry of Research and Technology (BMFT).
The aim of this research project was to verify, through field measurements, the performance projected from calculations based on theory, and to examine the influence of individual components on the plant’s output and efficiency under realistic engineering and meteorological
conditions.

Working Principle Of Solar Hybrid Chimney:
Man learned to make active use of solar energy at a very early stage: greenhouses helped to grow food, chimney suction ventilated and cooled buildings and windmills ground corn and pumped water.
The solar chimney’s three essential elements – glass roof collector, chimney, and wind turbines have thus been familiar from time immemorial.

Air is heated by solar radiation under a low circular glass roof open at the periphery; this and the natural ground below it form a hot air collector. Continuous 24 hours-operations is guaranteed by placing tight water-filled tubes under the roof. The water heats up during the daytime and emits its heat at night. These tubes are filled only once, no further water is needed. In the middle of the roof is a vertical chimney with large air inlets at its base. The joint between the roof and the chimney base is airtight. As hot air is lighter then cold air it rises up the chimney. Suction from the chimney then draws in more hot air from the collector, and cold air comes in from the outer perimeter. Thus solar radiation causes a constant up draught in the chimney. The energy this contains is converted into mechanical energy by pressure-staged wind turbines at the base of the chimney, and into electrical energy by conventional generators.

Advantages Of Solar Hybrid Chimney Power Plant:

A single solar chimney with a suitably large glazed roof area and a high chimney can be designed to generate 100 to 200 MW continuously 24 h a day. Thus even a small number of solar chimneys can replace a large nuclear power station.

Solar chimneys operate simply and have a number of other advantages:

The collector can use all solar radiation, both direct and diffused. This is crucial for tropical countries where the sky is frequently overcast. The other major large scale solarthermal power plants, parabolic through and central receiver systems, which apply concentrators and therefore can use only direct radiation, are at a disadvantage there.
Due to the heat storage system the solar chimney will operate 24h on pure solar energy. The water tubes lying under the glass roof absorb part of the radiated energy during the day and release it into the collector at night. Thus solar chimneys produce electricity at night as well.
Solar chimneys are particularly reliable and not liable to break down, in comparison with other solar generating plants. Turbines, transmission and generator – subject to a steady flow of air – are the plant’s only moving parts. This simple and robust structure guarantees operation that needs little maintenance and of course no combustible fuel.
Unlike conventional power stations (and also other solar-thermal power station types), solar chimneys do not need cooling water. This is a key advantage in the many sunny countries that already have major problems with drinking water.

Disadvantages Of Solar Hybrid Chimney Power Plant:

Some estimates say that the cost of generating electricity from a solar chimney is 5 times more than from a gas turbine. Although fuel is not required, solar chimneys have a very high capital cost.
The structure itself is massive and requires a lot of engineering expertise and materials to construct
In nights of winter season its efficiency lowers.