CN204089680U - A kind of condensation photovoltaic thermo-electric generation system - Google Patents

Abstract

The utility model discloses a kind of condensation photovoltaic thermo-electric generation system, comprising: thermo-electric generation sheet, fin, solar power generation sheet, wire, mirror condenser, heat conduction support, small opening, arrange that luminescent material is to increase incident intensity at solar cell panel area, solar panel can obviously be raised by temperature after solar concentrator, thermo-electric generation sheet is laid at the back side of solar panel, the hot junction of thermo-electric generation sheet is directly connected with solar power generation sheet, heat-conducting glue is filled to increase the heat transfer between solar power generation sheet and thermo-electric generation sheet hot junction between thermo-electric generation sheet and solar power generation sheet, then thermo-electric generation sheet cold junction is connected heat pipe by fin and directly link underground, make thermo-electric generation sheet cold junction temperature can carry out heat exchange with ground in this way, the temperature reducing solar panel improves generating efficiency, by thermo-electric generation sheet, its energy is carried out secondary utilization, considerably increases generating efficiency, effective reduction city temperature.

Description

A Concentrating Photovoltaic Thermoelectric Power Generation System

technical field

The utility model belongs to the technical field of solar power generation, in particular to a concentrating photovoltaic temperature difference power generation system.

Background technique

Photovoltaic power generation and thermoelectric power generation are two low-grade power generation methods in our life, that is to say, these two power generation methods have lower requirements for energy. Photovoltaic power generation is now relatively mature in both aerospace, military and civilian life. In the past, thermoelectric power generation has been shelved due to its poor reliability, short life and low efficiency. However, with the improvement of material properties, the reliability of temperature difference components increases, and thermoelectric power generation shows broad application prospects.

Photovoltaic power generation is that when light shines on the battery, part of the light will be absorbed by the semiconductor material. This means that the absorbed light energy will be transferred to the semiconductor. The energy causes electrons to escape allowing them to flow freely. Photovoltaic cells also have one or more electric fields that force electrons absorbed and released by light to flow in a certain direction. The flow of electrons creates an electric current, and by placing metal contacts on the top and bottom of the photovoltaic cell, we can draw the current out for use.

The principle of thermoelectric power generation is to combine one end of two different types of thermoelectric conversion materials N and P and place it in a high temperature state, and open the other end and give it a low temperature. Due to the strong thermal excitation at the high temperature end, the holes and electrons at this end Driven by the carrier concentration gradient, holes and electrons diffuse to the low-temperature end, thereby forming a potential difference at the low-temperature open-circuit end. By connecting many pairs of P-type and N-type thermoelectric conversion materials to form a module, a sufficiently high voltage can be obtained to form a thermoelectric generator. This kind of generator can directly convert heat energy into electric energy under the condition of small temperature difference, and does not need mechanical moving parts in the conversion process, and there is no gaseous or liquid medium, so it has a wide range of applications, small size, light weight, Safe and reliable, without any pollution to the environment, it is an ideal power supply. The flexible, green, quiet and small-sized characteristics of thermoelectric power generation make it play an important role in many fields.

No matter from the perspective of the world or China, conventional energy is very limited. China's primary energy reserves are far below the world's average level, only about 10% of the world's total reserves. With the production and development of people, the primary energy is gradually decreasing, and solar energy is an inexhaustible renewable energy source for human beings. It has sufficient cleanliness, absolute safety, relative universality, long life and The advantages of maintenance-free, resource adequacy and potential economy play an important role in the long-term energy strategy.

In the next ten years, China's photovoltaic power generation market will shift from independent power generation systems to grid-connected power generation systems, including desert power plants and urban rooftop power generation systems. The development potential of solar photovoltaic power generation in China is huge. Thermoelectric power generation technology has shown good application prospects in aerospace and military fields, and it has also developed rapidly in civilian fields in recent years. Although the efficiency of thermoelectric power generation is generally low now, with the research and development of new high-performance thermoelectric materials and reliable thermoelectric generators, thermoelectric power generation technology will give greater play to its advantages in the utilization of low-grade energy.

Utility model content

The purpose of the embodiment of the utility model is to provide a concentrating photovoltaic thermoelectric power generation system, aiming to solve the problems of poor reliability, short life and low efficiency in the existing thermoelectric power generation.

The embodiment of the utility model is achieved in this way, a concentrating photovoltaic thermoelectric power generation system, the concentrating photovoltaic thermoelectric power generation system includes: a thermoelectric power generation sheet, a heat sink, a solar power generation sheet, a wire, a reflective condenser mirror, a heat conducting bracket, and a leakage hole;

The thermoelectric power generation sheet is arranged on the back of the solar power generation sheet, the thermoelectric generation sheet is connected to the heat sink, the wire is connected to the thermoelectric generation sheet, the reflective condenser is arranged under the solar power generation sheet, and the heat conduction bracket is arranged on the outermost side of the concentrated photovoltaic thermoelectric power generation system, and is connected with the The heat sink is connected, and the leak hole is set at the center of the reflective condenser.

Furthermore, the concentrating photovoltaic thermoelectric power generation system adopts solar concentrating technology, and arranges luminescent materials around the solar panel to increase the intensity of incident light.

Further, the hot end of the thermoelectric power generation sheet is directly connected to the solar power generation sheet, and the cold end of the thermoelectric power generation sheet is directly connected to the ground through the cooling fin and the heat conduction pipe.

Further, thermal conductive glue is filled between the thermoelectric generation sheet and the solar generation sheet to increase heat conduction between the solar generation sheet and the hot end of the thermoelectric generation sheet.

Further, the method of calculating the efficiency of the thermoelectric power generation sheet:

The maximum power generation efficiency of a thermoelectric device is deduced as follows. When a thermoelectric material is used for power generation, the heat QT absorbed from the hot end is divided into three parts: First, when the current passes through the thermoelectric material, heat will be absorbed at the hot end and released at the cold end. heat, the heat absorbed from the hot end is αIT1; the second is heat conduction, which is κ(T1-T2)A/L (T1>T2); the third is internal resistance Joule heat, the calculation shows that the Joule heat transferred to the hot end and the cold end are respectively I2R/2; the energy output P on the load is I2RL; I is the current, T1, T2 are the temperature of the hot end and cold end respectively, RL is the load, L is the thickness of the material, A is the cross-sectional area, R is the internal resistance, R is expressed as R=L/σA; the power generation efficiency of thermoelectric materials is expressed as:

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}}{{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;\; I</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&kappa;</span>}\frac{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

RL=RS, the current I can be expressed as I=α(T1-T2)/R(1+S), when the temperature at both ends is constant, there is only one free variable in the above formula, and the above formula is derived from S and Let the derivative be 0, and the maximum efficiency is obtained as:

${\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, T is the average temperature at both ends (T1+T2)/2; when the material is at the maximum output efficiency, the ratio of the load to the internal resistance of the material is:

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

From formula (2), we know that the maximum power generation efficiency of a thermoelectric device is related to the material figure of merit Z and the operating temperature; the higher the figure of merit, the larger the temperature difference and the higher the power generation efficiency. The industrialized Bi ₂ Te ₃ based thermoelectric material ZT When the value is 1, its maximum operating temperature is 550K; when the high temperature end is 550K and the low temperature end is room temperature, the maximum power generation efficiency is close to 10%;

For different internal resistance R, when the efficiency is maximum, the output power and the corresponding input power are different; therefore, the internal resistance value, that is, the ratio of A/L should be determined according to the input power; the input power is QT, To make it have maximum output efficiency, then:

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;\&Delta;T</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Among them, ΔT is the temperature difference T1-T2; (4) can be obtained after transformation:

$\frac{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; S\&sigma;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

It can be seen from formula (5) that under a certain input power, the A/L ratio of the device should be reasonably designed to achieve the highest efficiency; it can also be known from formula (5) that when L decreases, A should also decrease , so the material volume AL can theoretically be infinitesimally small considering the energy flow density of solar energy. The thermoelectric element is designed to maximize the efficiency when the input power is 800W. The performance of the thermoelectric material adopts a typical value, and the conductivity is σ=1.0×10 ⁵ Ω ^-1 m ^-1 , the Seebeck coefficient is α＝1.9×10 ^-4 VK ^-1 , the thermal conductivity is κ＝1.5Wm ^-1 K ^-1 , the temperature at the high temperature end is 550K, the temperature at the low temperature end is 300K, and the TZ is 1.02 , A/L is designed to be 0.3m. If the thickness L is 1mm, the area A is 0.09cm ² . When twelve generators are connected in series, the voltage reaches 21.6V at a temperature difference of 40°C and 28.8V at a temperature difference of 60°C.

Further, the calculation method of solar power sheet efficiency:

The overall power generation efficiency PR _E formula is:

${\mathrm{<span\; class="notranslate">\; PR</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; PDR</span>}}{\mathrm{<span\; class="notranslate">\; PT</span>}}$

—PDR is the actual power generation in the test time interval (Δt);

—PT is the theoretical power generation within the test time interval (Δt);

In the theoretical power generation PT formula:

is the actual effective power generation time corresponding to the STC condition within the test time interval (Δt) of the photovoltaic power station;

-P is the nominal value of the module capacity under the STC condition of the photovoltaic power station;

-I0 is the total solar radiation value under STC conditions, Io=1000w/m ² ;

-Ii is the total solar radiation value during the test period; the calculated output voltage/current of the solar panel with the same size as the thermoelectric power generation sheet after concentrating light: 12V; mA.

The concentrating photovoltaic temperature difference power generation system provided by the utility model adopts solar concentrating technology, and arranges luminescent materials around the solar cell panel to increase the incident light intensity. After the solar cell panel passes through the solar concentrator, the temperature will increase significantly. Lay the thermoelectric power generation sheet on the back of the board, connect the hot end of the thermoelectric power generation sheet directly to the solar power generation sheet, fill the thermal conductive glue between the thermoelectric generation sheet and the solar power generation sheet to increase the heat conduction between the solar power generation sheet and the hot end of the thermoelectric generation sheet , and then directly connect the cold end of the thermoelectric generation sheet to the ground through the heat sink, so that the temperature of the cold end of the thermoelectric generation sheet can exchange heat with the ground in this way; not only can reduce the temperature of the solar panel and improve the power generation efficiency, Moreover, the energy can be reused through the thermoelectric power generation sheet, which greatly increases the power generation efficiency; if it is installed in the city, the heat exchange with the ground in summer can alleviate the heat island effect in the city and effectively reduce the city temperature. The utility model has the advantages of simple structure and convenient operation, and better solves the problems of poor reliability, short service life and low efficiency in the existing thermoelectric power generation.

Description of drawings

Fig. 1 is a schematic structural diagram of a concentrating photovoltaic thermoelectric power generation system provided by an embodiment of the present invention;

In the figure: 1. Thermoelectric power generation sheet; 2. Heat sink; 3. Solar power generation sheet; 4. Wire; 5. Reflective condenser; 6. Heat conduction bracket;

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

The application principle of the present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the concentrating photovoltaic thermoelectric power generation system of the embodiment of the utility model is mainly composed of: thermoelectric power generation sheet 1, heat sink 2, solar power generation sheet 3, wire 4, reflective condenser mirror 5, heat conducting bracket 6, leak hole 7;

The thermoelectric power generation sheet 1 is arranged on the back of the solar power generation sheet 3, the thermoelectric power generation sheet 1 is connected to the heat sink 2, the wire 4 is connected to the thermoelectric power generation sheet 1, the reflective concentrator 5 is arranged under the solar power generation sheet 3, and the heat conduction bracket 6 is arranged on the concentrated photovoltaic The outermost part of the thermoelectric power generation system is connected to the heat sink 2 , and the leakage hole 7 is set at the center of the reflective condenser 5 .

The utility model adopts the solar concentrating technology, arranges luminous materials around the solar panel to increase the incident light intensity, and the temperature of the solar panel will increase obviously after passing through the solar concentrator, and then lays a thermoelectric power generation sheet on the back of the solar panel The hot end of the thermoelectric power generation sheet is directly connected to the solar power generation sheet, and the heat conduction glue is filled between the two to increase the heat conduction between the solar power generation sheet and the hot end of the thermoelectric generation sheet; the cold end of the thermoelectric generation sheet is connected through a heat sink The heat pipe is directly connected to the ground, so that the temperature at the cold end of the thermoelectric sheet can exchange heat with the ground in this way; it not only reduces the temperature of the solar panel, improves the power generation efficiency, but also converts its energy into two through the thermoelectric sheet. Second utilization greatly increases the power generation efficiency; specific implementation methods are as follows:

1. Introduction to the principle of power generation

Photovoltaic power generation is that when light shines on the battery, a part of the light will be absorbed by the semiconductor material; this means that the absorbed light energy will be transferred to the semiconductor; the energy will cause electrons to escape so that they can flow freely; there is also one or Multiple electric fields can force the electrons absorbed and released by light to flow in a certain direction; the flow of electrons forms a current, and by placing metal contacts on the top and bottom of the photovoltaic cell, we can draw the current out for use;

The principle of thermoelectric power generation is to combine one end of two different types of thermoelectric conversion materials N and P and place it in a high temperature state, and open the other end and give it a low temperature; due to the strong thermal excitation at the high temperature end, the holes and electrons at this end The concentration is higher than that at the low-temperature end. Driven by this carrier concentration gradient, holes and electrons diffuse to the low-temperature end, thereby forming a potential difference at the low-temperature open-circuit end. Many pairs of P-type and N-type thermoelectric conversion materials are connected to form a module , you can get a high enough voltage to form a thermoelectric generator. This kind of generator can directly convert heat energy into electric energy under the condition of small temperature difference, and does not need mechanical moving parts in the conversion process, and there is no gaseous or liquid medium, so it has a wide range of applications, small size, light weight, Safe and reliable, without any pollution to the environment, it is an ideal power source. The flexible, green, quiet and small size of thermoelectric power generation makes it play an important role in many fields;

2. Calculation of power generation efficiency

2.1 Efficiency Calculation of Thermoelectric Generator

The maximum power generation efficiency of a thermoelectric device can be deduced as follows; the actual thermoelectric device is made of multiple pairs of P-type and N-type thermoelectric materials connected in series and thermally connected in parallel; a single piece of N-type or P-type material is used as the research object; When the thermoelectric material is used for power generation, the heat QT absorbed from the hot end is divided into three parts: first, when the current passes through the thermoelectric material, it will absorb heat at the hot end and release heat at the cold end, and the heat absorbed from the hot end is αIT1; the second is heat conduction, which is κ(T1-T2)A/L(T1>T2); the third is internal resistance Joule heat, and the calculation shows that the Joule heat transmitted to the hot end and the cold end is I2R/2; the energy on the load The output P is I2RL; here I is the current, T1 and T2 are the temperature of the hot end and the cold end respectively, RL is the load, L is the thickness of the material, A is the cross-sectional area, R is the internal resistance, and R can be expressed as R=L /σA; the power generation efficiency of thermoelectric materials is expressed as:

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}}{{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;I</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&kappa;</span>}\frac{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Assuming RL=RS, the current I can be expressed as I=α(T1-T2)/R(1+S). When the temperature at both ends is constant, there is only one free variable in the above formula, and the above formula is derived from S And let the derivative be 0, the maximum efficiency is obtained as:

${\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, T is the average temperature at both ends (T1+T2)/2; when the material is at the maximum output efficiency, the ratio of the load to the internal resistance of the material is:

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

It can be seen from formula (2) that the maximum power generation efficiency of thermoelectric devices is related to the material figure of merit Z and the operating temperature; the higher the figure of merit, the larger the temperature difference, the higher the power generation efficiency, but it cannot be higher than the Carnot efficiency; industrialization The ZT value of the Bi2Te3-based thermoelectric material is about 1, and its maximum operating temperature is about 550K; when the operating temperature of the high temperature end is 550K, and the low temperature end is room temperature, the maximum power generation efficiency is close to 10%;

For different internal resistance R, when the efficiency is maximum, the output power and the corresponding input power are different; therefore, the internal resistance value, that is, the ratio of A/L should be determined according to the input power; the input power is QT, to make it have the maximum output efficiency, then:

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;\&Delta;T</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Among them, ΔT is the temperature difference T1-T2; (4) can be obtained after transformation:

$\frac{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; S\&sigma;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

It can be known from formula (5) that under a certain input power, the A/L ratio of the device should be reasonably designed to achieve the highest efficiency; it can also be known from formula (5) that when L decreases, A should also decrease Small, so the amount of material volume AL can theoretically be infinitely small. Considering the energy flow density of solar energy, the thermoelectric element is designed to maximize the efficiency when the input power is 800W. The performance of the thermoelectric material adopts a typical value, and the conductivity is σ=1.0× 10 ⁵ Ω ^-1 m ^-1 , the Seebeck coefficient is α＝1.9×10 ^-4 VK ^-1 , the thermal conductivity is κ＝1.5Wm ^-1 K ^-1 , the temperature at the high temperature end is 550K, the temperature at the low temperature end is 300K, and TZ is 1.02, A/L is designed to be 0.3m, if the thickness L is 1mm, then the area A is 0.09cm ² .

It can be proved that when multiple pairs of N-type and P-type materials are used in electrical series and thermal parallel, the maximum efficiency remains unchanged, and when the thickness remains unchanged, the amount of thermoelectric material remains unchanged, but the internal resistance and output voltage increase, and the output The current drops; ns can be connected in series with N-type and P-type materials, as if the material with area A is cut into 2ns blocks and then connected in series; after series connection, the current density in the thermoelectric material is the same as before, but the output voltage is the original 2ns times, the output current becomes the original 1/2ns; the size of the output current is related to the thickness of the lead-out wire, the larger the ns, the thinner the lead-out wire, the lower the cost of the wire; but the more logarithms in series, the manufacturing of thermoelectric elements The more complicated the process is; in the above-mentioned power generation unit, when twelve power generation pieces are connected in series, the voltage reaches 21.6V at a temperature difference of 40°C, and 28.8V at a temperature difference of 60°C;

The output of the voltage regulator module is 12V, 5A. To charge the 12V lead-acid battery, 14.5V-15V is needed, and a boost circuit is needed; find a 12V to 14.5V boost circuit, which has high efficiency and small size, and fully meets the requirements;

2.2 Calculation of efficiency of solar power generation sheet:

The overall power generation efficiency PR _E formula is:

${\mathrm{<span\; class="notranslate">\; PR</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; PDR</span>}}{\mathrm{<span\; class="notranslate">\; PT</span>}}$

—PDR is the actual power generation in the test time interval (Δt);

—PT is the theoretical power generation within the test time interval (Δt);

In the theoretical power generation PT formula:

is the actual effective power generation time corresponding to the STC condition within the test time interval (Δt) of the photovoltaic power station;

-P is the nominal value of the module capacity under the STC condition of the photovoltaic power station;

-I0 is the total solar radiation value under STC conditions, Io=1000w/m ² ;

-Ii is the total solar radiation value during the test period;

After calculation, the output voltage/current of the solar panel with the same size as the thermoelectric power generation sheet after concentrating: 12V; about mA;

3. The concentrating photovoltaic thermoelectric power generation system of this utility model adopts solar concentrating technology, and arranges luminescent materials around the solar panel to increase the incident light intensity; and the temperature of the solar panel will increase significantly after passing through the solar concentrator, so it is convenient Lay thermoelectric power generation sheets on the back of the solar panel;

The hot end of the thermoelectric power generation sheet is directly connected to the solar power generation sheet, and the heat conduction glue is filled between the two to increase the heat conduction between the solar power generation sheet and the hot end of the thermoelectric generation sheet;

The cold end of the thermoelectric sheet is directly connected to the ground through the heat pipe connected by the heat sink, so that the temperature of the cold end of the thermoelectric sheet can exchange heat with the ground in this way.

The concentrating photovoltaic thermoelectric power generation system of the utility model not only reduces the temperature of the solar panel and improves the power generation efficiency, but also uses the energy for the second time through the thermoelectric power generation sheet, which greatly increases the power generation efficiency; and if it is installed in the city, Heat exchange with the ground in summer can alleviate the heat island effect in the city and effectively reduce the city's temperature; generate electricity through this power generation method, and then store the electricity; the stored electricity can be used in people's daily life; such as street lighting, emergency power supply wait.

The concentrating photovoltaic temperature difference power generation system of the utility model combines photovoltaic power generation and temperature difference power generation to increase the utilization of solar energy; and this power generation method can utilize the waste heat of photovoltaic power generation and increase the efficiency of photovoltaic power generation; The technology has greatly increased the power generation efficiency and reduced the cost input; the installation of concentrated photovoltaic power generation in the city can try to build a temporary car charging station, which can provide emergency charging for electric vehicles driving on the road when the power is exhausted.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model shall be included in this utility model. within the scope of protection of utility models.

Claims (4)

1. A concentrating photovoltaic thermoelectric power generation system, characterized in that the concentrating photovoltaic thermoelectric power generation system comprises: a thermoelectric power generation sheet, a heat sink, a solar power generation sheet, a wire, a reflective condenser, a thermally conductive support, and a leak hole; The thermoelectric power generation sheet is arranged on the back of the solar power generation sheet, the thermoelectric generation sheet is connected to the heat sink, the wire is connected to the thermoelectric generation sheet, the reflective condenser is arranged under the solar power generation sheet, and the heat conduction bracket is arranged on the outermost side of the concentrated photovoltaic thermoelectric power generation system, and is connected with the The heat sink is connected, and the leak hole is set at the center of the reflective condenser. 2. The concentrated photovoltaic thermoelectric power generation system according to claim 1, characterized in that the concentrated photovoltaic thermoelectric power generation system adopts solar energy concentration technology, and luminescent materials are arranged around the solar panels to increase the incident light intensity. 3. The concentrated photovoltaic thermoelectric power generation system according to claim 1, characterized in that the hot end of the thermoelectric power generation sheet is directly connected to the solar power generation sheet, and the cold end of the thermoelectric power generation sheet is directly connected to the ground through a heat sink connected to a heat pipe. 4. The concentrating photovoltaic thermoelectric power generation system according to claim 1, characterized in that, thermal conductive glue is filled between the thermoelectric power generation sheet and the solar power generation sheet to increase heat conduction between the solar power generation sheet and the hot end of the thermoelectric power generation sheet.