CN108800605A - A kind of solar energy heat collection pipe and thermo-electric generation system - Google Patents

Abstract

The invention discloses a solar thermoelectric power generation system, which comprises: a solar heat collection device, a thermoelectric power generation device and a heat storage device. The solar thermal collector converts solar radiation into thermal energy, provides heat to the thermoelectric power generation device, and stores the remaining heat in the thermal storage device. When there is no sunlight, the heat storage device supplies heat to the thermoelectric power generation device, thereby realizing continuous power generation. The invention also discloses a solar heat collection tube, which comprises a glass tube, a tube cover, a linear Fresnel lens placed in the glass tube, a heat absorbing plate, a heat transfer tube, and a thermal insulation layer of the heat transfer tube. The invention obtains medium and low temperature solar heat in a way with lower cost and stably uses it in thermoelectric conversion, and has better economy.

Description

A kind of solar heat collecting tube and temperature difference power generation system

technical field

The invention relates to a solar heat collecting tube and a solar thermoelectric power generation system, belonging to the technical field of solar power generation.

Background technique

With the continuous progress of solar power generation technology, solar energy has become an important form of power source, and is increasingly valued by countries all over the world. There are two main ways of solar power generation: photovoltaic power generation and solar thermal power generation, both of which have reached the level of large-scale grid-connected power generation. The existing photothermal power generation technology is similar to coal-fired power generation. The high temperature obtained through solar concentration is used to generate steam, thereby driving the steam turbine to do work. Solar thermoelectric power generation uses the Seebeck effect of thermoelectric materials to convert solar heat into electrical energy, and does not require the power cycle equipment of existing photothermal generator sets. Therefore, it has no moving parts, no noise, easy miniaturization, easy control, and high reliability. , Long life and other advantages. In recent years, the technology of thermoelectric materials has been booming, and commercial applications have been greatly developed. Combining with the existing solar heat collection technology, a new type of solar thermal power generation technology with potential competitiveness can be formed.

In view of the low performance of existing thermoelectric materials, the efficiency of thermoelectric power generation is low, and it is not enough to compete with photovoltaic or concentrating solar thermal power generation technologies in terms of power generation efficiency. However, thermoelectric power generation can use medium and low temperature solar thermal power generation. Medium and low temperature solar heat is easy to obtain, and the corresponding thermoelectric materials are also very mature. From the perspective of the price per unit of power generation, it can form certain advantages. The problem existing in the existing technology is that the heat collection temperature is usually lower than 150°C, which is lower than the optimum working temperature of conventional thermoelectric power generation ( 200°C and above), further increasing the heat collection temperature will cause a sharp drop in heat collection efficiency and poor power generation economy. The concentrating methods of medium and high temperature solar thermal power generation, such as trough type, tower type, and dish type, require complex concentrating heat collection systems, and the cost is too high. Therefore, it is an urgent problem to be solved to obtain medium and low temperature solar heat in a cheaper way and stably use it for thermoelectric conversion.

Contents of the invention

In view of the above technical problems, the present invention provides a solar heat collecting tube and a solar thermoelectric power generation system.

One aspect of the present invention provides a solar collector tube, comprising a tube body and a Fresnel lens located in the tube body, a heat absorbing plate and a heat transfer tube, wherein the Fresnel lens is suspended above the heat absorbing plate, and sunlight passes through The Fresnel lens is focused onto the heat absorbing plate, which converts the solar radiation energy into heat, thereby obtaining medium and low temperature solar heat.

Preferably, the Fresnel lens is a linear Fresnel lens. Preferably, the concentration ratio of the linear Fresnel lens is more than 5, and the width of the heat absorbing plate can be suitably larger than the width of the concentration band formed by the linear Fresnel lens, so as to reduce the sun tracking accuracy requirement and simplify the tracking device.

Further, the tube body of the solar heat collection tube of the present invention includes a glass tube and a tube cover. Further, only one end of the glass tube is open, and the open end is sealed by the tube cover, and the glass tube is evacuated to form a vacuum cavity. The Fresnel lens is placed in a vacuum glass tube to reduce environmental aging and is not disturbed by wind.

Further, one side of the heat absorbing plate of the solar heat collection tube of the present invention has a solar selective absorption coating, and the other side is in contact with the heat transfer tube, preferably, can be welded with the heat transfer tube. The linear Fresnel lens focuses the sunlight to the solar selective absorption coating of the heat absorbing plate, and the heat absorbing plate absorbs the solar radiation energy through the solar selective absorption coating and converts it into heat, which is transferred to the heat transfer tube in the heat transfer tube medium.

Furthermore, the inlet and outlet of the heat transfer tube pass through the tube cover and protrude out of the tube, and the heat collected by the heat absorbing plate is transferred out of the heat collecting tube through the flow of the heat transfer medium in the heat transfer tube. Further, the heat absorbing plate and the heat transfer tube are made of metal materials, preferably copper, aluminum and other metal materials with good thermal conductivity. Further, the heat transfer tube is wrapped with a heat transfer tube heat insulating layer, which is used for heat insulation of the heat transfer tube.

Another aspect of the present invention provides a solar thermoelectric power generation system, including a solar heat collection device and a thermoelectric power generation device, wherein the solar heat collection device includes one or more solar heat collection tubes of the present invention, and the solar heat collection device will The solar radiation is converted into heat, which is transmitted to the thermoelectric power generation device, and further converted into electrical energy by the thermoelectric heating device.

Further, the solar heat collecting device of the present invention also includes a mounting bracket on which the solar heat collecting tube is installed, and the mounting bracket is provided with a rotating mechanism, which can make the solar heat collecting tube rotate axially to track sunlight.

Further, the thermoelectric power generation device of the present invention includes a plate-fin heat exchanger, a thermoelectric power generation module, and a water cooling device, wherein the plate-fin heat exchanger is a flat structure, and its upper and lower heat exchange planes are in contact with the thermoelectric power generation module to dissipate heat Transfer to the hot end of the thermoelectric power generation module to keep the hot end at a higher temperature. The water cooling device is in contact with the cold end of the thermoelectric power generation module to reduce the temperature of the cold end. Further, there is heat insulating material between the thermoelectric power generation modules.

Further, the thermoelectric power generation device of the present invention further includes a side heat insulating layer, and the side heat insulating layer wraps both sides of the plate-fin heat exchanger to reduce heat loss at the side of the plate-fin heat exchanger.

The thermoelectric power generation module of the present invention can use the temperature difference between the hot end and the cold end to generate electricity, and convert a part of the heat in the heat transfer medium into electric energy. It can be a conventional commercial thermoelectric power generation chip, preferably, it can be a thermoelectric power generation chip made of Bi2Te3 material.

Further, the water-cooling device of the present invention is a water-cooling bag, wherein the water-cooling bag is connected with a water pump and a cooling tower to form a loop, and the cooling water is driven by the water pump to circulate between the water-cooling bag and the cooling tower, and the cooling tower is the final heat sink.

Further, the solar thermoelectric power generation system of the present invention includes one or more sets of thermoelectric power generation devices, preferably two or more groups. Further, the outlets of the plate-fin heat exchangers of the multiple thermoelectric power generation devices are connected to the pipes after being collected.

Furthermore, the solar thermoelectric power generation system of the present invention also includes a power conversion device connected to the thermoelectric power generation module to convert the electric energy output by the thermoelectric power generation device into a mode required by the user.

Further, the solar thermoelectric power generation system of the present invention further includes an energy storage device, and the energy storage device, the solar thermal collector and the thermoelectric power generation device are connected through pipelines to form a loop. Further, the energy storage device includes a high-pressure water storage tank and a heat exchanger. The heat exchanger is placed in the high-pressure water storage tank, and can transfer the heat of the heat transfer medium in the heat exchanger to the high-pressure water, and store energy through the high-pressure water. Further, the solar thermoelectric power generation system of the present invention may include multiple sets of heat storage devices connected in parallel, preferably two or more sets. Further, the outlets of the heat exchangers of the multiple parallel heat storage devices are collected and connected to the pipeline.

Further, the solar thermoelectric power generation system of the present invention also includes a bypass pipe and a valve, the bypass pipe bypasses the solar heat collector, and directly connects the heat storage device and the thermoelectric power generation device, and the valve can control the heat transfer in the pipe Whether the medium flows through the solar collector. Preferably, the valve is a three-way valve arranged at the port of the bypass pipeline, and whether the heat transfer medium in the pipeline flows through the solar heat collection device can be controlled by switching the three-way valve.

Further, the solar thermoelectric power generation system of the present invention further includes a circulation pump, which is arranged on the pipeline and can drive the heat transfer medium to circulate in the pipeline.

When the solar thermoelectric power generation system of the present invention is working, the heat collecting tube tracks the sunlight and converts the solar radiation energy into heat energy, wherein the linear Fresnel lens focuses the sunlight on the heat absorbing plate, and the solar energy selectively absorbs the coating on the heat absorbing plate Absorb solar radiation energy, convert it into heat and transfer it to the heat-absorbing plate, and the heat-absorbing plate transmits heat to the heat transfer medium through the heat transfer tube, and the heat transfer medium is continuously supplied to the plate-fin heat exchanger in the thermoelectric power generation device driven by the circulating pump. Heat, the remaining heat is transferred to the water through the heat exchanger in the high-pressure water storage tank, the hot end surface of the thermoelectric power generation module is heated by the plate-fin heat exchanger, the cold end surface is cooled by the water cooling bag, the water cooling bag is provided with cooling water by the water pump, and the cooling tower is the final heat source. trap. When there is no sunlight, the valve is switched so that the heat transfer medium bypasses the heat collecting tube, and the high-pressure water storage tank provides heat for the thermoelectric power generation device, so that 24-hour continuous power generation can be realized and the system cost can be reduced.

The invention uses a linear Fresnel lens to focus in a vacuum glass tube to obtain medium and low temperature solar heat, and then generates electricity through temperature difference. Compared with the prior art, it can obtain higher solar heat, and the temperature difference power generation efficiency is higher.

Description of drawings

Fig. 1 is a schematic diagram of a solar thermoelectric power generation system;

Fig. 2 is a schematic diagram of a longitudinal section of a heat collecting tube;

Fig. 3 is a cross-sectional schematic diagram of a heat collecting tube;

Fig. 4 is a cross-sectional schematic diagram of a thermoelectric power generation device;

in:

1-solar collector tube, 2-installation bracket, 3-thermoelectric power generation device, 4-high pressure water storage tank, 5-heat exchanger, 6-circulating pump, 7-three-way valve, 8-water pump, 9-cooling tower, 10 -Power conversion device, 11-glass tube, 12-linear Fresnel lens, 13-heat absorbing plate, 14-heat transfer tube, 15-heat transfer tube insulation layer, 16-tube cover, 31-plate-fin heat exchange device, 32-thermoelectric power generation module, 33-water cooling bag, 34-side insulation layer.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope of the present invention.

As shown in Figure 1, in one embodiment of the present invention, the solar thermoelectric power generation system includes a solar heat collector, a thermoelectric power generation device 3 and a heat storage device, wherein the solar heat collector, the thermoelectric power generation device 3 and the heat storage device pass through the pipeline They are connected in sequence to form a loop, and the heat transfer medium can circulate through the pipes between the solar heat collector, the thermoelectric power generation device 3 and the heat storage device to transfer heat. The solar thermoelectric power generation system is also provided with a bypass pipe, which bypasses the solar heat collector and directly connects the thermoelectric power generation device 3 and the heat storage device. In this embodiment, the inlet of the bypass pipeline is provided with a three-way valve 7, and whether the heat transfer medium in the pipeline flows through the solar heat collection device can be controlled by switching the three-way valve 7. In other embodiments of the present invention, other methods may also be adopted, for example, the flow direction of the heat transfer medium may be controlled through cooperation of a plurality of common valves arranged on different pipelines.

As shown in FIG. 1 , the solar thermoelectric power generation system further includes a circulation pump 6 , which is arranged on the pipeline and can drive the heat transfer medium to circulate in the pipeline. In this embodiment, the circulation pump 6 is located between the three-way valve 7 and the heat storage device, and its outlet is connected to the inlet of the three-way valve 7 . However, those skilled in the art can understand that the position of the circulation pump in the present invention is not limited thereto, as long as it can drive the heat transfer medium to circulate in the pipeline.

The solar heat collecting device comprises a mounting bracket 2 and a solar heat collecting tube 1 fixed on the mounting bracket 2, wherein the mounting bracket 2 is equipped with a rotating mechanism for axially rotating the solar heat collecting tube 1, and during use, the rotating rotating mechanism can make the solar heat collecting tube 1 axial rotation to track the sunlight. In the present invention, the solar heat collecting device may include one or more solar heat collecting tubes.

As shown in FIG. 2 , the solar heat collection tube 1 includes a tube body and a linear Fresnel lens 12 placed in the tube body, a heat absorbing plate 13 , a heat transfer tube 14 and a thermal insulation layer 15 for the heat transfer tube. Wherein the tube body includes a glass tube 11 and a tube cover 16, the glass tube 11 is only open at one end, and the open end is sealed by the tube cover 16, and the glass tube 11 is evacuated to form a vacuum cavity. The linear Fresnel lens 12 is suspended above the heat absorbing plate 13, one side of the heat absorbing plate 13 has a solar selective absorption coating, and the other side is welded with the heat transfer tube 14, and the heat absorbing plate 13 and the heat transfer tube 14 can be controlled by thermal conductivity. It can be made of good metal materials, such as copper, aluminum and other metal materials. The heat transfer tube 14 is wrapped with a heat transfer tube heat insulating layer 15 for heat insulation of the heat transfer tube 14 . The inlet and outlet of the heat transfer tube 14 pass through the tube cover 16 and stretch out of the glass tube 11 to be connected with the pipeline. The heat transfer medium flows in through the inlet of the heat transfer tube, and flows out through the outlet, transferring the heat in the solar collector tube. When the solar heat collecting device includes a plurality of solar heat collecting tubes, the pipelines are connected in parallel to the heat transfer tube inlets of the solar heat collecting tubes, and the outlets of the heat transfer tubes are collected and connected to the pipelines in parallel.

As shown in Figure 3, the sunlight is focused on the solar selective absorption coating of the heat absorbing plate 13 through the linear Fresnel lens 12, and the heat absorbing plate 13 absorbs the solar radiation energy through the solar selective absorbing coating and converts it into heat, heat The heat is transferred to the heat transfer medium in the heat transfer pipe 14 through the heat transfer pipe 14 . Preferably, the light-gathering ratio of the linear Fresnel lens 12 adopted in the solar collector tube 1 is more than 5, and the width of the heat-absorbing plate 13 can be suitably greater than the light-gathering band width formed by the linear Fresnel lens 12, to reduce the solar Tracking accuracy requirements.

As shown in Figure 4, the thermoelectric power generation device includes a plate-fin heat exchanger 31, a thermoelectric power generation module 32, a water cooling bag 33, and a side insulation layer 34, wherein the plate-fin heat exchanger 31 is a flat structure, and its upper and lower two The thermal plane is in contact with the thermoelectric power generation module 32 , and when the heat transfer medium flows through the plate-fin heat exchanger 31 , it transfers heat to the hot end of the thermoelectric power generation module 32 to keep the hot end at a higher temperature. Both sides of the plate-fin heat exchanger 31 can be wrapped with side insulation layers 34 to reduce heat loss at the sides of the plate-fin heat exchanger 31 .

The thermoelectric power generation module 32 uses the temperature difference between the hot end and the cold end to generate electricity, and converts heat into electrical energy. In the present invention, the thermoelectric power generation module 32 can be a conventional commercial thermoelectric power generation chip, for example, a thermoelectric power generation chip made of Bi2Te3 material can be selected. As shown in Figure 4, the hot end surface of the thermoelectric power generation module 32 is in contact with the heat exchanger 31, heated by the heat exchanger 31, and the cold end surface is in contact with the water cooling bag 33, cooled by the water cooling bag 33, and there is a heat insulating material between the thermoelectric power generation modules .

As shown in FIG. 1 , the water cooling bag 33 is connected to the water pump 8 and the cooling tower 9 to form a loop, and the cooling water is driven by the water pump 8 to circulate between the water cooling bag 33 and the cooling tower 9 , and the cooling tower 9 is the final heat sink.

The solar thermoelectric power generation system of the present invention may further include a power conversion device 10 connected to a thermoelectric power generation module 32 to convert the electric energy output by the thermoelectric power generation device 3 into a mode required by the user. In the present invention, the solar thermoelectric power generation system may include one or more sets of parallel thermoelectric power generation devices 3, preferably two or more groups; The outlets of the plate-fin heat exchangers of the device are collected and connected to the heat storage device through pipes.

The heat storage device includes a high-pressure water storage tank 4 and a heat exchanger 5 . The heat exchanger 5 is placed in the high-pressure water storage tank 4. When the heat transfer medium flows through the heat exchanger 5, heat can be transferred to the high-pressure water, thereby storing the remaining heat through the high-pressure water. In the present invention, the solar thermoelectric power generation system may include one or more sets of heat storage devices connected in parallel, preferably two or more sets. When multiple heat storage devices connected in parallel are included, the outlets of the heat exchangers of the multiple heat storage devices are collected and connected to pipelines.

The various devices of the solar thermoelectric power generation system of the present invention are connected by pipelines, and valves, instruments and other equipment can also be arranged on the pipelines according to the needs of system control. The solar thermoelectric power generation system can also include auxiliary facilities, electrical systems, control systems, etc.

The specific implementation steps of the solar thermoelectric power generation system provided in this embodiment are as follows:

In the case of sunlight, the solar collector tube 1 rotates axially to track the sunlight under the action of the driving mechanism of the mounting bracket 2, and the linear Fresnel lens 12 focuses the sunlight to the heat absorbing plate 13, and the heat absorbing plate 13 The solar selective absorbing coating on the surface absorbs solar radiation energy and converts it into heat, and the heat is transferred to the heat transfer medium through the heat transfer tube 14, and the heat transfer medium is continuously exchanged to the plate fins in the thermoelectric power generation device 3 under the drive of the circulating pump 6. The heat exchanger 31 provides heat, and the remaining heat of the heat transfer medium is transferred to the water through the heat exchanger 5 in the high-pressure water storage tank 4 . The hot end side of the thermoelectric power generation module 32 is heated by the plate-fin heat exchanger 31, for example: heated to 200°C, and the cold end side is cooled by the water cooling bag 33, for example: to 35°C, the water cooling bag 33 is provided with cooling water by the water pump 8, cooling Column 9 is the final heat sink.

When there is no sunlight, the three-way valve 7 is switched, the heat transfer medium bypasses the heat collecting tube 1, and circulates between the heat storage device and the thermoelectric power generation device, and the high-pressure water storage tank 4 provides heat for the thermoelectric power generation device 3, thereby enabling Realize continuous power generation. The thermoelectric power generation module 32 selects the most widely used Bi2Te3 material thermoelectric power generation chip, uses the temperature difference between the hot end and the cold end to generate electricity, and the output electric energy is converted into the electric energy mode required by the user through the power conversion device 10 .

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any form and in essence. Several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. Those who are familiar with this profession, without departing from the spirit and scope of the present invention, when they can use the technical content disclosed above to make some changes, modifications and equivalent changes of evolution, are all included in the present invention. Equivalent embodiments; at the same time, all changes, modifications and evolutions of any equivalent changes made to the above-mentioned embodiments according to the substantive technology of the present invention still belong to the scope of the technical solution of the present invention.

Claims (10)

1. a solar collector tube, comprising a tube body, a heat absorbing plate positioned in the tube body and a heat transfer tube, the heat absorbing plate is in contact with the heat transfer tube, and the inlet and outlet of the heat transfer tube stretch out of the tube body, characterized in that , the tube body also includes a Fresnel lens, and the Fresnel lens is suspended above the heat absorbing plate. 2 . The solar heat collection tube according to claim 1 , wherein the Fresnel lens is a linear Fresnel lens with a light concentration ratio greater than 5. 3 . 3. The solar heat collecting tube according to claim 1, wherein the heat absorbing plate is made of metal material. 4. The solar heat collection tube according to claim 1, wherein the heat transfer tube is wrapped with a heat insulating layer. 5. A solar thermoelectric power generation system, comprising a solar heat collector and a thermoelectric power generation device, the solar heat collector is connected to the thermoelectric power generation device, and transfers heat to the thermoelectric power generation device, it is characterized in that the solar heat collector includes right The solar heat collecting tube described in any one of requirements 1-4. 6. The solar thermoelectric power generation system as claimed in claim 5, characterized in that, the solar heat collection device also includes a mounting bracket, the solar heat collecting tube is installed on the mounting bracket, and the mounting bracket is provided with a solar collector A rotary mechanism for the axial rotation of the heat pipe. 7. The solar thermoelectric power generation system according to claim 5, further comprising an energy storage device, the energy storage device, the solar thermal collector and the thermoelectric power generation device are connected by pipelines. 8. The solar thermoelectric power generation system according to claim 7, wherein the energy storage device comprises a high-pressure water storage tank and a heat exchanger, and the heat exchanger is placed in the high-pressure water storage tank. 9. The solar thermoelectric power generation system as claimed in claim 8, characterized in that, the solar thermoelectric power generation system also includes a bypass pipeline and a valve, and the bypass pipeline bypasses the solar heat collector and directly connects the heat storage device and In the thermoelectric power generation device, the valve can control whether the heat transfer medium in the pipeline flows through the solar heat collection device. 10. The solar thermoelectric power generation system as claimed in claim 5, wherein the thermoelectric power generation sub-device comprises a thermoelectric power generation sheet, a plate-fin heat exchanger and a water-cooled bag, and the hot end and the cold end of the thermoelectric power generation sheet are in contact with each other respectively. Plate-fin heat exchanger and water cooling bag.