WO2009116073A2

WO2009116073A2 - Co-generation of power and cooling from solar heat and bio-waste (biogas)/industrial waste

Info

Publication number: WO2009116073A2
Application number: PCT/IN2009/000082
Authority: WO
Inventors: Arvindbhai Lavjibhai Patel
Original assignee: Alp Multitech Pvt. Ltd.
Priority date: 2008-02-08
Filing date: 2009-02-05
Publication date: 2009-09-24
Also published as: WO2009116073A3

Abstract

A power generation system consists with vacuum tube (1 ), parabolic reflector (2), heat pipe (3), TE module (4), heat exchanger (5), storage tank (6), DC to AC converter (7) and mechanism and electronic tracking system (8); and hybrid system additionally consists with header tank (9), insulated heat pipe (10) and burner (11 ). The parabolic reflectors (2) collect thermal energy in the vacuum tube (1); the heat is transferred to the hot junction of the TE module (4) by means of heat pipe (3); the cold junction is maintained by water/fluid flow in the heat exchanger (5) attached to it; the heat extracted at the cold junction by the heat exchanger (5) is taken to the storage tank (6); the DC to AC converter (7) get desired input from the temperature difference of two junctions of the TE module (4); the sun tracking system (8) is mounted on the parabolic reflectors (2) to concentrate on the vacuum tube (1 ) the received solar energy throughout the day; the header tank (9) collects auxiliary heat by insulated heat pipes (10) from the another directional burner (11 ). In the case of low power solar energy and at night, hybrid system uses waste bio-mass or bio gas or industrial waste to generate the power.

Description

Co-generation of Power and cooling from solar heat and bio-waste (biogas)/ Industrial waste

Energy is the key input to drive and improve the life cycle. Primarily, it is the gift of the nature to the mankind in various forms. The consumption of the energy is directly proportional to the progress of the mankind. With ever growing population, improvement in the living standard of the humanity, industrialization of the developing countries, the global demand for energy is expected to increase rather significantly in the near future. The primary source of energy is fossil fuel, however the finiteness of fossil fuel reserves and large scale environmental degradation caused by their widespread use, particularly global warming, urban air pollution and acid rain, strongly suggests that harnessing of non-conventional, renewable and environment friendly energy resources is vital for steering the global energy supplies towards a sustainable path.

To meet the future energy demands and to give quality and pollution free supply to the growing and today's environment conscious population, the present world attention is to go in for natural, clean and renewable energy sources. These energy sources capture their energy from on-going natural processes, such as geothermal heat flows, sunshine, wind, flowing water and biological processes.

Most renewable forms of energy, other than geothermal and tidal power ultimately come from the Sun. Some forms of energy, such as rainfall and wind power are considered short-term energy storage, whereas the energy in biomass is accumulated over a period of months, as in straw, and through many years as in wood. Fossil fuels too are theoretically renewable but on a very long time-scale and if continued to be exploited at present rates then these resources may deplete in the near future. Therefore, in reality, Renewable energy is energy from a source that is replaced rapidly by a natural process and is not subject to depletion in a human timescale.

Renewable energy resources may be used directly, such as solar ovens, geothermal heating, and water and windmills or indirectly by transforming to other more convenient forms of energy such as electricity generation through wind turbines or photovoltaic cells, or production of fuels (ethanol etc.) from biomass.

There is more than enough solar radiation available all over the world to satisfy a vastly increased demand for solar power systems. The sunlight which reaches the earth's surface is enough to provide 2,850 times as much energy as we can currently use. On a global average, each square metre of land is exposed to enough sunlight to produce 1,700 kWh of power every year.

Solar energy can be used in two ways:

Solar heating. • Solar electricity.

Solar heating is to capture/concentrate sun's energy for heating buildings and for cooking/heating foodstuffs etc. Solar electricity is mainly produced by using photovoltaic solar cells which are made of semi-conducting materials that directly convert sunlight into electricity. Obviously the sun does not provide constant energy to any spot on the Earth, so its use is limited. Therefore, often Solar cells or any other source either as secondary energy source or for other applications of intermittent use such as night lighting or water pumping etc. India is a vast country with an area of over 3.2 million sq. km. Most parts of the country have about 250-300 sunny days. India has average sunlight irradiation of 5.4- 6.2 KW hr/m2/ day.

India is still agro based economy so; we can get plenty of bio-waste. In addition, India is now known as global manufacturing hub so plenty of industrial/ solid waste would be available for our project. All waste has unused caloric value and it has also problem of disposal too. Hence our concept is to take out, to collect to store heat and then to generate electricity by thermo electric generation (TEG) modules.

The creation of electrical power by thermoelectric means was discovered by TJ. Seebeck in 1821 that if two identical junctions of two dissimilar metals are joined in a single circuit then a minute current will flow around the circuit when one junction is held at a higher temperature than the other. The current flows because of a difference in electrical potential between the junctions. The product of the potential difference (volts) and the current (amperes) determines the power derived (watts). Since the potential produced per cell is very small many cells have to be connected in series in order to create a potential difference large enough to deliver useful quantities of power to an external load. The numbers are such as to render thermo-electric generation impractical in most applications (for example the number of junctions in series could be 50,000 or above).

One well known use of the Seebeck effect is in thermocouple temperature sensing apparatus where thin wires of dissimilar metals are used to generate a voltage proportional to the temperature difference between the junctions of the wires. In recent years many proposals have been made to use the thermo-electric generating properties of semiconductor materials because semiconductor thermoelectric generators (TEG's) can produce about twenty times the voltage of a metal/metal TEG.

Growth of urban area pushes us to more demand of cooling and air- conditioning requirements. To fulfill such requirements, the present invention relates to Co-generation of Power and cooling from solar heat and bio-waste (biogas)/ Industrial waste is invented.

The present invention is described with greater specific and clarity with reference to following drawings:

Fig. 1 Schematic diagram of solar thermal power generation with reflector tracking Fig.2 Schematic diagram of Hybrid system

Fig.3 Schematic diagram of steam Generation unit with reflector tracking Fig.4 Schematic diagram of Sun tracking device

As shown in Fig.l, the present invention system consists with vacuum tube (1), parabolic reflector (2), heat pipe (3), TE module (4), Heat exchanger (5), Storage tank (6), DC to AC Converter (7) and mechanism and electronic tacking system (8). The power generation unit works on concentrated sunlight by parabolic trough reflectors (2). Collected thermal energy in the vacuum tube (1) receiver at the focal point of parabolic profile is transferred to the hot junction of Thermo Electric module (4) by means of heat pipe (3). Heat pipe is a device for fast heat transfer. The outer shell is usually made from copper or steel having high thermal conductivity and manufacturability. Working medium is a phase changing material which is inside the partially vacuumed shell. The value of vacuum and properties of phase changing material depends on the magnitude and temperatures of heat transfer. When the bottom portion of the heat pipe is kept at elevated temperature with reference to condenser portion (which is heat rejection portion), the material inside the shell heats up and changes its phase from liquid to vapour or solid to vapour and fills the entire volume of the shell and gives the heat to condenser from where the heat is taken out externally. This process takes heat from vapour and converts it into its original form of liquid or solid and comes down due to higher density than vapour. This cycle continues and makes constant heat transfer for the desired purpose.

Thermoelectric modules (4) work on seeback effect. TE module consists of two surface, which are required to be kept at hot and cold temperature respectively. Cold junction is maintained by water/fluid flow in a heat exchanger (5) attached to it. The temperature develops in the thermic fluid is as high as 400 ⁰C. , while running in no thermal load condition, while running on load as TE module , the typical temperature gradient to be maintained between hot and cold junction is 200 ⁰C. The heat extracted at cold junction by heat exchanger(5) is taken to a storage tank (6) which gives hot fluid as bi-product and can be used for other purposes. The series of mechanically connected troughs is achieved to facilitate system integration and net power output. The system is kept sun directional by means of the mechanism and electronic sun tracking system (8) to achieve concentration on vacuum tube receivers throughout the day. The electrical power generated due to the temperature difference of two junctions of TE module is connected in series/parallel to get desired input for DC to AC converter (7). The AC output of the system can be used as standalone system or as grid connected. In Fig. 2, the hybrid system takes care of low sunny days and night time as when the solar energy is not available, the system is run by auxiliary fuel which is typically biogas, biomass, natural gas or any heat source. As the result, a constant thermal energy is gained which is used for electrical power generation or suitable purposes.

The system works on concentrated sunlight by parabolic trough reflectors (2). Collected thermal energy in the vacuum tube (1) receiver at the focal point of parabolic profile is transferred to the working fluid inside the header tank (9) by means of heat pipe (3). The specially shaped header tank allows auxiliary heat collection by insulated heat pipes (10) from another direction (typically backside). Burner (11) or suitable arrangement is kept to heat up each heat pipe at auxiliary side. The system is automatically switched to auxiliary fuel in case of low sunlight situation to maintain the required temperature of working fluid in header tank. Inlet and outlet valves are provided for desired constant or intermittent flow of working fluid as per system requirement. The series of mechanically connected troughs is achieved to facilitate system integration and net heat output. The system is kept sun directional by means of the mechanism and electronic sun tracking system (8) to achieve concentration on vacuum tube receivers throughout the day.

The steam generation unit works on concentrated sunlight by parabolic trough reflectors (2). Collected thermal energy in the vacuum tube (1) receiver at the focal point of parabolic profile is transferred to the water kept in header tank (9) by means of heat pipe (3). The series of mechanically connected troughs is achieved to facilitate system integration and net steam output. The system is kept sun directional by means of the mechanism and electronic sun tracking system (8) to achieve concentration on vacuum tube receivers throughout the day. The steam generated in the header tank at required pressure is taken out intermittently by switching of outlet valve.

The sun tracker, as shown in Fig. 4 is an electronic device which gives signal to motor drive as per the sun sensing to move the mechanism/profile towards the sun direction and to maintain the same. It consists of sensors (12) to sense the sun position. The tracking is done single as well as double axis. Double axis sun tracking takes care of elevation as well as azimuth angle of the sun while the single axis tracking takes care of either of elevation or azimuth angle. The electronic circuit (13) takes the input from sensors, processes it and gives output signal to tracking motor driver which is mounted on a master mechanism to which all the troughs of series are connected. The tracking circuit also consists of home position command which turns the troughs to initial position in morning time.

The power generator generates the power by using the light of the sun, no fuel is required, further since the substance is not burned as is different from the conventional one, no carbon dioxide is generated. Accordingly, it is possible to provide an ideal environment protection type power generation plant. Further since the burning itself requires no cost at all, the running cost is very low, and it is possible to provide a power generation plant having a lower cost than the convention power generation plant.

Claims

We Claims:

1. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste system consists with vacuum tube (1), parabolic reflector (2), heat pipe (3), TE module (4), heat exchanger (5), storage tank (6), DC to AC converter (7) and mechanism and electronic tacking system (8) with power generation system and hybrid system is additionally consists with header tank (9), insulated heat pipe (10) and burner (11); wherein

the parabolic reflectors (2) collected thermal energy in the vacuum tube (l);

the parabolic profile is transferred to the hot junction of TE module (4) by means of heat pipe(3);

the cold junction is maintained by water/fluid flow in a heat exchanger (5) attached to it;

the heat extracted at cold junction by heat exchanger is taken to a storage tank (6);

DC to AC converter (7) get desired input from the temperature difference of two junctions of TE module;

sun tracking system (8) is mounted on the parabolic reflectors to concentration on vacuum tube to receive solar energy throughout the day;

the header tank (9) collect auxiliary heat collection by insulated heat pipes (10) from another directional burner (11).

2. Co-generation of Power and cooling from solar heat and bio- waste (bioga^'s)/ Industrial waste as claimed in claim 1 wherein temperature gradient to be maintained between hot and cold junction is 200 ⁰C.

3. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste as claimed in claim 1 wherein the electrical power generated due to the temperature difference of two junctions of TE module is connected in series/parallel to get desired input for DC to AC converter (7)

4. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste as claimed in claim 1 wherein hybrid system run by auxiliary fuel which is typically biogas, biomass, natural gas or any heat source.

5. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste as claimed in claim 1 wherein in the hybrid system concentrated sunlight by parabolic trough reflectors (2). Collected thermal energy in the vacuum tube (1) receiver at the focal point of parabolic profile is transferred to the working fluid inside the header tank (9) by means of heat pipe (3).

6. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste as claimed in claim 1 wherein the specially shaped header tank allows auxiliary heat collection by insulated heat pipes (10) from another direction.

7. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste as claimed in claim 1 wherein burner is kept to heat up each pipe at auxiliary side.

8. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste as claimed in claim 1 wherein sun tracker (1) consists of sensors, electronic circuit (2) and mounting flange (3).

9. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste as claimed in claim 1, wherein heat pipe consists with condenser, phase changing material and outer shell.

10. Co-generation of Power and cooling from solar heat and bio- waste (biogas)/ Industrial waste substantially herein described with reference to the foregoing description and the accompanying drawings.