KR20100108849A - Complex energy conversion systems in solar cell and method of energy conversion using the same - Google Patents

Abstract

PURPOSE: A complex energy conversion system in a solar cell and an energy conversion method using the same are provided to improve the generation efficiency of a solar cell by lowering the surface temperature of the solar cell using nano-fluid. CONSTITUTION: A complex energy conversion system in a solar cell comprises a photoelectric converter(100), a heat exchanger(104), nano-fluid(110), a hot water supplier(105), and a nano-fluid feeder. The photoelectric converter is made of a crystalline system or amorphous semiconductor and provides electricity through photoelectric conversion. The heat exchanger restricts the surface temperature increase of the photoelectric converter and recovers heat on the rear side of the photoelectric converter. The nano-fluid is heated and then moves along a flow passage. The hot water supplier creates hot water using the nano-fluid. The nano-fluid feeder transfers the nano-fluid used in the hot water supplier to the heat exchanger.

Description

Complex Energy Conversion Systems in Solar Cell and method of energy conversion using the same}

The present invention relates to a complex energy conversion system and a method for energy conversion using the same in a solar cell, and more particularly to produce electricity by using a photoelectric converter, recovering the heat formed on the back of the photoelectric converter to provide hot water The present invention relates to a complex energy conversion system in a solar cell and an energy conversion method using the same.

The present invention combines a solar generator that can efficiently generate electrical energy using solar light and a solar collector that can efficiently generate thermal energy using solar heat can generate power and hot water simultaneously from solar energy. The present invention relates to a complex energy conversion system in a solar cell and an energy conversion method using the same.

Solar cells have the largest energy source among renewables and the highest feasibility. The use of solar cells has attracted attention as the most ideal alternative energy because it is free from CO ₂ concerns. However, the reason why the ratio of energy production according to solar cells is not so high is that the efficiency of power generation is low. In general, the polysilicon solar cell module shows an efficiency of about 6%. If the efficiency is increased to 7 to 8%, a cost reduction of about 15 to 30% can be achieved. Therefore, efforts are being made to increase the efficiency of such solar cells.

1 is a graph showing a decrease in efficiency with increasing temperature of a crystalline silicon solar cell and an amorphous silicon solar cell. When the surface temperature of a solar cell rises, both the crystalline silicon solar cell and the amorphous silicon solar cell show that the efficiency of a battery falls. It can be seen that the crystalline silicon solar cell is more rapidly deteriorated in efficiency than the amorphous silicon solar cell.

Irradiation of high density solar energy on the surface of crystalline silicon solar cell can increase the output of the solar cell, but at the same time, most of the solar energy absorbed by the solar cell is not converted to electricity, and surplus energy increases the temperature of the solar cell to improve efficiency. Lowers. In this case, the solar cell should be cooled in order to prevent deterioration of the cell efficiency. In particular, in the case of a solar cell using a concentrator, the design of the device must be accompanied by a suitable cooling device according to the concentration ratio.

In the case of low convergence ratio (low density energy), the cooling system may use simple passive devices (eg natural ventilation), and in the case of high concentration type, forced or active cooling means should be used. That is, it is possible to lower the temperature of the solar cell by using forced ventilation or by contacting the structure of the cooling fin with the back of the solar cell and allowing the working medium (eg, air, water, etc.) to flow into the inner space of the fin structure. Can be. The higher the focusing ratio, the higher the temperature of the solar cell, and therefore the temperature of the cooling medium also rises at the same flow rate.

2 illustrates a method of directly spraying cooling water onto a surface of the photoelectric conversion module according to the related art. 2 is in the development of the East-West power plant in East-West power generation, but there is a problem that the problem of light incident efficiency decrease due to the recovery of the coolant and the injection of the coolant is expected.

Research on solar cell-solar consolidation device that absorbs high temperature heat through special cooling device in solar cell heated by high density solar energy and makes it possible to use the heated (cooling) medium directly for the necessary use It is becoming.

Photovoltaic-solar energy combining devices are known from US Pat. No. 6,675,580 and US Pat. No. 6,295,818. M. Brogren, "Optical Efficiency of Low-Concentrating Solar Energy Systems with Parabolic Reflectors," Uppsala, Ph.D. University, Ph.D. Thesis, 2004) and “J. s. Dr. Conventry, Ph.D. Dissertation (Australia), "Solar Concentrating Photovoltaic / Thermal Collector", Australlian National University, Ph.D. Thesis, 2004).

As such, the discussion on the use of a combination of solar cells and solar thermal energy continues, but there is a problem in that the efficiency of solar cells has not been dramatically improved.

In order to solve the above problems, the present invention is an energy conversion system that generates power and heat at the same time in one energy source is excellent in cooling performance, maximize the efficiency of the solar cell complex energy in the solar cell to increase the energy utilization efficiency It is an object to provide a conversion system.

In order to solve the above problems, an object of the present invention is to provide a complex energy conversion method in a solar cell that can increase the economic efficiency by combining the production of electricity and hot water while increasing the production efficiency of electricity in the conventional solar power system. It is done.

In order to achieve the above object, the present invention

A photoelectric converter composed of a crystalline system or an amorphous semiconductor and supplying electricity through a photoelectric conversion reaction;

A heat exchanger for suppressing an increase in the surface temperature of the photoelectric converter and recovering heat on the rear surface of the photoelectric converter;

A nanofluid that moves along the flow passage after being used as a working fluid in the heat exchanger and warmed up;

A hot water supply unit for generating hot water using the nanofluid; And

It provides a complex energy conversion system in a solar cell comprising a nanofluid supply for supplying the nanofluid used in the hot water supply to the heat exchanger.

In order to achieve the above another object, the present invention

In the solar energy conversion method comprising a photoelectric converter and a heat exchanger,

Supplying nanofluid to a backside of the photoelectric converter from a nanofluid supply;

Nanofluid flows through a flow path provided on the rear surface of the photoelectric converter to lower the surface temperature of the photoelectric converter and recover heat;

Moving the heat-recovered nanofluid to a hot water supply along a predetermined flow path; And

It provides a complex energy conversion method in a solar cell comprising the step of generating hot water using the heat of the nanofluid in the hot water supply.

According to the present invention, it is possible to increase the power generation efficiency of the battery by lowering the surface temperature of the solar cell using the nanofluid, and to maximize the energy efficiency according to the use of the solar cell by recovering the arrangement of the solar cell to provide hot water. have.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The present invention is composed of a crystalline or amorphous semiconductor photoelectric converter for supplying electricity through a photoelectric conversion reaction; A heat exchanger for suppressing an increase in the surface temperature of the photoelectric converter and recovering heat on the rear surface of the photoelectric converter; A nanofluid that moves along the flow passage after being used as a working fluid in the heat exchanger and warmed up; A hot water supply unit for generating hot water using the nanofluid; And a nanofluid supply for supplying the nanofluid used in the hot water supply to the photoelectric converter.

In order to solve the problem that the surface temperature is high due to the concentration of light in the use of a high efficiency solar cell, the present invention provides a heat exchanger to cool the solar cell, and the heat exchanger operates a nano fluid having excellent thermal conductivity. Use as a fluid. Heat generated by using nanofluids may be recovered to generate hot water and used as heating and / or hot water for a house or building.

When the surface temperature of the solar cell increases by 1 ° C, the amount of power generation decreases by 0.5%. If the heat exchanger is installed in order to reduce the increase of the surface temperature of the solar cell, the power generation amount may increase as the temperature decreases. Cogeneration system according to the present invention can reduce the surface temperature of the photoelectric converter and improve the power output.

According to another embodiment of the present invention, there is provided a solar energy conversion device including a photoelectric converter and a heat exchanger, comprising: supplying a nanofluid to a rear surface of the photoelectric converter from a nanofluid supply; Nanofluid flows through a flow path provided on the rear surface of the photoelectric converter to lower the surface temperature of the photoelectric converter and recover heat; Moving the heat-recovered nanofluid to a hot water supply along a predetermined flow path; And it provides a temperature control method of the solar energy conversion device comprising the step of generating hot water using the heat of the nano-fluid in the hot water supply.

3A and 3B show a schematic diagram of a complex energy conversion device in a solar cell according to an embodiment of the present invention.

Referring to FIG. 3A, a tempered glass 101 is installed on a front surface of the photoelectric converter 100, and a back sheet 103 is attached to a rear surface thereof. Moreover, the photoelectric conversion device is sealed on the side surface of the photoelectric converter 100 using the exterior material 102. Solar light transmitted through the tempered glass 101 produces power through the photoelectric converter 100 and supplies it to the power supply 130. As the sunlight is exposed, the surface temperature of the photoelectric converter 100 rises and the heat exchanger 104 installed on the backside of the photoelectric converter 100 reduces the increased temperature of the photoelectric converter 100. The nanofluid 110, which acts as a working fluid in the heat exchanger 104, is heated up and moves along the flow passage. The heated nanofluid is used to generate hot water in the hot water supply 105. The generated hot water is used for hot water or heating in a house or office, and the nanofluid 111 used to generate hot water in the hot water supply 105 moves to the nanofluid supply 107. The nanofluid supplier 107 serves to supply the nanofluid to the photoelectric converter 100, and a pump 106 is installed to force the nanofluid to circulate. In FIG. 3A, the heat recovered from the photoelectric converter is moved to the hot water supply 105 in the form of nanofluid, and the hot water supply 105 is supplied with water 119 and converted into hot water 120 to be supplied to the room. Doing.

Referring to FIG. 3B, a tempered glass 201 is installed on a front surface of the photoelectric converter 200, and a back sheet 203 is attached to a rear surface thereof. In addition, the photoelectric conversion device is sealed on the side surface of the photoelectric converter 200 by using the exterior material 202. Solar light transmitted through the tempered glass 201 produces power through the photoelectric converter 200 and supplies it to the power supply 230. As the sunlight is exposed, the temperature of the surface of the photoelectric converter 200 rises and the heat exchanger 204 installed on the backside of the photoelectric converter 200 lowers the increased temperature of the photoelectric converter 200 surface. After acting as a working fluid in the heat exchanger 204, the heated nanofluid 210 moves along the flow passage. The migrated nanofluid warms the supplied water 219 without warming from the hot water supply 205 to generate hot water 220. The generated hot water 220 is used for hot water or heating in a house or office. The system also includes a pump 206 for forced circulation of the nanofluid to the photoelectric converter 200. 3B illustrates an embodiment in which the nanofluid supply 207 and the hot water supply 205 are integrated. 3B differs from FIG. 3A in that the heat recovered from the photoelectric converter is transferred to the nanofluid supply 207, converted to hot water 220, and moved to a desired place.

4 shows a schematic diagram comprising a photoelectric converter and a heat exchanger according to the invention. Referring to FIG. 4, the nanofluid flows through a heat exchanger formed on the rear surface of the panel 100. The nanofluid is introduced through the supply port 150, is discharged through the discharge port 151, and lowers the surface temperature of the panel while the back surface of the panel flows, and heat exchange is performed while the nanofluid is heated up.

To reduce the temperature of the flat or condensed photoelectric conversion module, attach a micro heat exchanger, a heat pipe type heat exchanger, a plate heat exchanger, a channel heat exchanger, or a heat collector to the back sheet, and apply nanofluid as a heat transfer medium for these heat exchangers. .

A micro heat exchanger is a type in which fluid is exchanged through a microchannel, and a micro heat exchanger is a miniature version of a conventional tubular heat exchanger. It comprehensively includes all heat exchange systems that conduct heat in micro-sized regions, such as microchannels and porous channels, which dominate the heat transfer characteristics of two fluids rather than the heat exchanger itself. Micro heat exchanger can make the product small and light, and can diversify the place of use.

The heat pipe type heat exchanger is a vacuum exhaust after injecting nanofluid in a sealed container. The heat pipe type heat exchanger transfers heat by using latent heat without any external power. Heat pipes are capable of mass transfer of heat by latent heat, uniform temperature distribution, light weight, and simple structure. In addition, the responsiveness is fast and it is possible to separate the heating portion and the cooling portion, and in the case of thermophony, the heat is used only in one direction.

The plate heat exchanger is a high-strength bolted bolt to the support and the heat exchanger assembly. The heat exchanger assembly consists of an embossed stainless plate. Each heat plate is assembled in a corrugated form in opposite directions so that the two fluids flow in opposite flows and can be separated by a gasket. Plate heat exchanger has wrinkles on residual heat plate, so it has high heat transfer efficiency and almost complete counterflow flow, so it is not only efficient heat exchange but also applicable to temperature difference of 1 ℃, so it can be used even when temperature difference is low and installation cost is low. Low maintenance and repair costs

5A and 5B show the shape of a plate heat exchanger flow path disposed on the back of the photoelectric converter. Referring to FIG. 5A, the nanofluid is supplied from the supply port 150, moves along the plate-shaped flow path 152, and is discharged to the outside of the panel through the discharge port 151. Referring to FIG. 5B, the nanofluid is supplied from the supply port 153, moves along the plate-shaped flow path 155, and is discharged to the outside of the panel through the discharge port 154. Heat exchange takes place while the nanofluid passes through the plate-shaped flow path, thereby lowering the panel temperature, and the nanofluid itself is heated up and discharged to the outside.

Nanofluids are fluids made by dispersing and suspending fibers of the same size as nanoparticles or nanotubes in a general fluid. Nanofluid is preferably composed of one or more nanoparticles selected from the group consisting of Al ₂ O ₃ , CuO, Cu, Pt and Au. In general, the size of the nanoparticles dispersed in the nanofluid is 10 to 100nm, preferably 10 to 50nm, the technique of dispersing and floating the nanoparticles can be largely divided into physical and chemical methods.

The physical methods can be classified into two types. The first method is the One Step Method process, in which a substance to be dispersed and suspended in a general fluid is vaporized in a high vacuum chamber, and the vaporized material is in contact with a general fluid that is around a high vacuum chamber. It is a technology that forms nanoparticles and at the same time disperses and floats in a fluid. The second method is a two-step method, in which nanofluids are manufactured by separating the nanoparticles production steps and the steps of dispersing and floating them in a fluid.

The chemical method refers to a method of dispersing and suspending nanoparticles by maintaining a dispersibility of the particles using a surfactant to change the surface of the nanoparticles, or by controlling the fluid pH (pH).

The thermal properties of nanofluids improve the effective thermal conductivity of nanofluids by about 10% and the convective heat transfer characteristics by up to 30% even if a small volume fraction of nanoparticles is added to the general fluid. In addition, the thermal conductivity of the nanofluid increases rapidly with temperature change, and the characteristics of the nanofluid mean that the thermal conductivity increases as the temperature of the nanofluid increases, thereby increasing the heat transfer rate.

In addition, the smaller the size of the nanoparticles, the higher the thermal conductivity. The thermal conductivity of conventional thin films with nano size decreased as the thickness of the thin film decreased, but the thermal properties of nanofluids are reversed. This thermal characteristic is that the critical heat flux of nanofluid is about three times larger than the critical heat flux of normal fluid. It is understood that the nanofluid is suitable for use as a working fluid because of its excellent cooling performance and heat transfer characteristics in the heat exchanger of the solar energy converter.

It is preferable that the photoelectric converter is a planar or condensed photoelectric converter. In general, solar collectors use a flat plate. However, the flat plate collector has a very low efficiency of converting into electricity or heat energy, and thus has limitations in use. Therefore, concentrators (e.g., parabolic troughs, parabolic dishes, fresnel lenses, etc.) are used to increase the efficiency of converting solar energy into electric energy or heat energy, and at the same time apply them in various ways. The focusing device uses an optical device (lens or reflector) to focus the solar energy incident on the aperture of the device into a high-density energy output on the smaller exit surface (light-receiving or endothermic). It is a device that generates significantly higher or higher temperature thermal energy to improve the efficiency (performance) of the device. At the same time, depending on the type and design of the focusing device, the unit cost of the device can be reduced.

6A and 6B show a light converging photoconversion device in which a film is installed and a light converging light conversion device with fins, respectively. Fins are attached for cooling the rear surface, and in the present invention, nanofluid is applied as a heat transfer medium to improve heat transfer performance.

Cogeneration system is a comprehensive energy system that generates power and heat simultaneously from a single energy source. Photovoltaic power generation system is to increase the efficiency of energy overall heat utilization by using the power generated in the photovoltaic power generation system and recovering and using the arrangement generated in the photoelectric conversion module. Therefore, the present invention is a high-efficiency energy utilization technology that can increase the economics compared to the existing photovoltaic system by combining and producing electricity and heat.

Photovoltaic combined cycle power generation system is an energy utilization technology that utilizes the recovered arrangement while reducing the temperature of the photoelectric conversion device by mounting a heat recovery heat exchanger on the back of the conventional photoelectric conversion module. Therefore, the surface temperature of the photoelectric conversion device is suppressed to increase the efficiency of the power production device, and the heat recovered by using the nanofluid can be reused to produce hot water for efficient use of energy.

The cooling water surface spraying method used for conventional photoelectric conversion module cooling causes problems such as water treatment cost and cooling efficiency due to cooling water injection, thereby reducing the temperature of the light conversion module by recovering heat from the back sheet. The method is effective. Since the photoelectric conversion device of the present invention requires more rapid cooling and it is difficult to expect high heat transfer performance with a conventional heat transfer medium, a nanofluid with improved thermal conductivity is applied as a heat transfer medium to solve the problem.

It is preferable to further provide an auxiliary power device that can further supply power in accordance with the amount of power supplied from the photoelectric converter. The photoelectric converter may vary in the amount of power produced according to the amount of sunshine. Therefore, when the photoelectric converter is used alone in an independent house or building, variations in power generation occur due to changes in seasons or weather, and in such a case, it is necessary to further provide auxiliary power means so that electricity can be stably supplied. Do. Therefore, when the amount of sunlight is abundant, the auxiliary power means is not used or minimized. When the amount of sunlight is insufficient, the auxiliary power means is used to assist the photoelectric converter.

Preferably, the hot water supply further includes an auxiliary heat supply that operates selectively according to the temperature of the hot water. Therefore, if the amount of sunshine is not used or minimize the auxiliary heat supply, if the amount of sunlight is insufficient to use the auxiliary heat supply to assist the nanofluid supply. That is, when the amount of solar radiation is large, taking warm water from the nanofluid and warming, when the amount of solar radiation is low may further comprise the step of heating the hot water from the auxiliary heat supply.

1 is a graph showing a decrease in efficiency with increasing temperature of a crystalline silicon solar cell and an amorphous silicon solar cell.

2 illustrates a method of directly injecting cooling water to the surface of a photoelectric conversion module according to the related art.

3A and 3B show schematic diagrams of a solar energy conversion apparatus according to an embodiment of the present invention.

4 shows a schematic diagram comprising a photoelectric converter and a heat exchanger according to the invention.

5A and 5B illustrate the shape of a plate heat exchanger flow path for mounting a backsheet according to the present invention.

6A illustrates a schematic diagram of a light collecting photoelectric conversion module according to an embodiment of the present invention, and FIG. 6B illustrates a schematic diagram of a pinned light collecting photoelectric conversion module according to an embodiment of the present invention.

Claims (11)

A photoelectric converter composed of a crystalline system or an amorphous semiconductor and supplying electricity through a photoelectric conversion reaction; A heat exchanger for suppressing an increase in the surface temperature of the photoelectric converter and recovering heat on the rear surface of the photoelectric converter; A nanofluid that moves along the flow passage after being used as a working fluid in the heat exchanger and warmed up; A hot water supply unit for generating hot water using the nanofluid; And Complex energy conversion system in a solar cell comprising a nanofluid supply for supplying the nanofluid used in the hot water supply to the heat exchanger. The complex energy conversion system of claim 1, wherein the photoelectric converter is a condensing type or a flat type photoelectric converter. The complex energy conversion system of claim 1, further comprising an auxiliary power device capable of supplying additional power according to the amount of power supplied from the photoelectric converter. The complex energy conversion system of claim 1, wherein the heat exchanger is a micro heat exchanger, a heat pipe heat exchanger, a plate type heat exchanger, or a channel type heat exchanger. The complex energy conversion system of claim 1, wherein the nanofluid comprises one or more nanoparticles selected from the group consisting of Al ₂ O ₃ , CuO, Cu, Pt, and Au. The complex energy conversion system of claim 1, wherein the size of the nanoparticles used in the nanofluid is 10 to 100 nm. The complex energy conversion system of claim 1, wherein the hot water supply further includes an auxiliary heat supply that selectively operates according to the temperature of the hot water. In the energy conversion system in a solar cell comprising a photoelectric converter and a heat exchanger, Supplying nanofluid to a backside of the photoelectric converter from a nanofluid supply; Nanofluid flows through a flow path provided on the rear surface of the photoelectric converter to lower the surface temperature of the photoelectric converter and recover heat; Moving the heat-recovered nanofluid to a hot water supply along a predetermined flow path; And Composite energy conversion method in a solar cell comprising the step of generating hot water using the heat of the nano-fluid in the hot water supply. The complex energy conversion method of claim 8, wherein the photoelectric converter is a condensing type or a flat type photoelectric converter. The method of claim 8, wherein the heat exchanger is a micro heat exchanger, a heat pipe heat exchanger, a plate type heat exchanger, or a channel type heat exchanger. The complex energy conversion method of claim 8, further comprising heating the hot water from the nanofluid when the amount of solar radiation is high and heating the hot water from an auxiliary heat supply when the amount of solar radiation is low. .

Images