CN107061201A - A kind of photovoltaic and photothermal coupling co-generation unit and method - Google Patents

Abstract

The invention belongs to the field of solar energy utilization, and in particular relates to a system and method for cogeneration of heat and power coupled with photovoltaic light and heat. The system is composed of a heat collection subsystem, a power generation subsystem and a heat supply subsystem connected in series; the heat collection subsystem includes photovoltaic photoelectric integrated components and a compound parabolic heat collector; , a heat exchanger, a condenser, a liquid storage tank and a working medium pump in series; the heat supply subsystem is composed of a heat exchanger and a heat user. The invention combines photovoltaic power generation with low-temperature photothermal organic Rankine cycle power generation, uses the heat generated by photovoltaic power generation to preheat the working medium, reduces the heat collection area per unit electric power, and supplies heat while generating electricity. To make full use of solar energy resources, realize "temperature matching, cascade utilization", and improve the thermal efficiency and economy of the whole system.

Description

Photovoltaic-thermal coupled heat and power cogeneration system and method

technical field

The invention belongs to the field of solar energy utilization, and in particular relates to a system and method for coupling heat and power cogeneration with photovoltaic light and heat.

Background technique

Energy and environmental issues have accelerated the development of clean energy and renewable energy to replace traditional fossil energy power generation technologies. Solar power generation technology is valued for its huge energy storage capacity, safety and cleanliness. Solar power generation technologies mainly include photovoltaic power generation and photothermal power generation. Photovoltaic power generation is a power generation technology that uses the principle of photovoltaics to directly convert solar energy into electrical energy through solar panels; photothermal power generation is a power generation method that converts solar energy into heat energy through a heat collector, and the heating medium works in the form of a Rankine cycle to drive a generator. . While photovoltaic power generation converts a small part of solar energy into electrical energy, more solar radiation is converted into heat, which increases the temperature of the panel. Excessively high temperature will reduce the power generation efficiency and service life of the panel, and at the same time, the loss of heat also wastes solar energy resources. If the heat that needs to be dissipated by solar panels can be used as a part of the heat source for photothermal power generation, solar energy resources can be effectively utilized and the economy of solar power generation can be improved.

The organic Rankine cycle uses low-boiling-point organic matter instead of water as the circulating working medium, which can effectively use the low-temperature heat source to generate steam with sufficient pressure to drive the steam turbine to do work, thereby improving energy utilization efficiency. The organic Rankine cycle system has simple structure, high safety performance, and low maintenance cost. Compared with other low-temperature heat source utilization technologies, its efficiency advantage is obvious. Through the development in recent years, the organic Rankine cycle power generation technology has gradually moved from the laboratory to the demonstration stage.

Based on the above background, a photovoltaic photothermal coupled heat and power cogeneration system is proposed to improve the comprehensive utilization efficiency of solar energy and optimize the system economy through the combination of the two.

Contents of the invention

The purpose of the present invention is to propose a photovoltaic photothermal coupled heat and power cogeneration system, which not only generates electricity, but also provides heat to heat users, realizes cascade utilization of energy, and makes full use of solar energy resources.

Technical scheme of the present invention is as follows:

A photovoltaic photothermal coupled heat and power cogeneration system, which is composed of a heat collection subsystem, a power generation subsystem, and a heat supply subsystem connected in series;

The heat collection subsystem includes a photovoltaic photoelectric integrated component and a compound parabolic heat collector;

The power generation sub-system is composed of an expander, a generator, a heat exchanger, a condenser, a liquid storage tank and a working medium pump in series;

The heating subsystem consists of heat exchangers and heat users.

Preferably, the integrated photovoltaic components are composed of solar panels and heat exchange components, and a plurality of integrated photovoltaic components are formed into an array of integrated photovoltaic components through a series-parallel structure.

Preferably, the plurality of compound parabolic heat collectors are composed of a compound parabolic heat collector array through a series-parallel structure.

Preferably, the electric energy of the photovoltaic photothermal coupled heat and power cogeneration system comes from photovoltaic power generation of photovoltaic photoelectric integrated components and power generation of generators.

A method for cogeneration of photovoltaic, light and heat coupled heat and power using the above system, the method comprising the following steps:

S1, the working fluid is pressurized by the working fluid pump, and then the photovoltaic photoelectric integrated module absorbs the heat of the back plate of the battery board, so that the temperature of the working fluid is initially raised;

S2, the working medium further absorbs solar energy heat collection through the compound parabolic heat collector assembly, so that the temperature is raised and vaporized into high-temperature and high-pressure steam;

S3, the high-temperature and high-pressure steam of the working medium becomes low-pressure steam after the expander works to drive the generator to generate electricity;

S4, the low-pressure steam of the working medium transfers part of the heat to the heat medium in the heat exchanger, and then fully releases heat through the condenser to condense to liquid and store it in the liquid storage tank, and then circulates again through the working medium pump.

Preferably, the step S1 further includes: the heat generated by the solar cell while generating electricity is transferred to the working fluid through the heat exchange component.

Preferably, the step S2 further includes: concentrating light onto the heat-absorbing coating of the inner tube of the vacuum tube through the compound paraboloid, and then transferring heat to the working fluid flowing in the internal heat exchange component through the heat-absorbing coating.

Preferably, the step S4 further includes: providing the low-pressure spent steam at the outlet of the expander to heat supply users after passing through the heat exchanger.

The beneficial effect of the present invention is that: the present invention combines photovoltaic power generation with low-temperature photothermal organic Rankine cycle power generation, uses the heat generated by photovoltaic power generation to preheat the working medium, reduces the heat collection area per unit of electric power, and supplies electricity while generating electricity. hot. To make full use of solar energy resources, realize "temperature matching, cascade utilization", and improve the thermal efficiency and economy of the whole system.

Description of drawings

Figure 1 is a structural diagram of a photovoltaic photothermal coupled heat and power cogeneration system;

Among them: 1-PVT component, 2-CPC component, 3-expander, 4-generator, 5-heat user, 6-heat exchanger, 7-condenser, 8-liquid storage tank, 9-working fluid pump, 7-1- Refrigerant.

Figure 2 is a layout diagram of PVT module and CPC module heat collector array;

Among them: 1-PVT array arrangement, 2-CPC array arrangement.

Fig. 3 is the sectional view of PVT plate cross section;

Among them: 1-1-tempered glass cover plate, 1-2-photovoltaic cell film, 1-3-metal substrate, 1-4-heat exchange tube, 1-5-insulation material, 1-6-encapsulation shell.

Fig. 4 is the cross-sectional view of CPC board cross section;

Among them: 2-1-Composite reflective paraboloid, 2-2-Glass vacuum tube, 2-3-Selective absorption coating, 2-4-Fin heat absorption tube.

detailed description

The embodiments will be described in detail below in conjunction with the accompanying drawings.

Embodiment one:

Photovoltaic thermal coupled heat and power cogeneration system consists of three parts, as shown in Figure 1, the first part: heat collection system; the second part: power generation system; the third part: heating system.

The heat collection system comprises two parts, a PVT assembly (1) and a CPC assembly (2).

The PVT assembly (1) is a PVT array composed of a plurality of PVT plates connected in series and in parallel to meet flow and heat load requirements. As a preheater of the organic Rankine cycle, the PVT module works in the low temperature region (below 60°C).

Described PVT plate is known structure, comprises (with reference to Fig. 3 cross-sectional structure): toughened glass cover plate (1-1), photovoltaic cell thin film (1-2), metal substrate (1-3), heat exchange tube ( 1-4), thermal insulation material (1-5) and packaging shell (1-6).

The CPC assembly is a CPC array composed of a plurality of CPC boards connected in series and in parallel to meet flow and heat load requirements. As the evaporator of the organic Rankine cycle, the CPC component further increases the temperature of the working fluid and evaporates into steam, and the outlet steam temperature is between 90°C and 150°C.

Described CPC plate is known structure, comprises (with reference to Fig. 4 cross-sectional structure) composite reflective paraboloid (2-1), glass vacuum tube (2-2), selective absorbing coating (2-3) and internal heat absorbing Finned tubes (2-4).

The wall thickness of the metal heat-absorbing pipe in the PVT board and the CPC board is designed to be increased accordingly to meet the pressure bearing requirements of the system, for example, a copper pipe with a wall thickness of 1-2 mm is used.

The power generation system includes an expander (3), a generator (4), a heat exchanger (6), a condenser (7), a liquid storage tank (8) and a working medium pump (9). The high-temperature and high-pressure organic working medium vapor is expanded by the expander (3) to drive the generator (4) to generate electricity. The expanded low-pressure working medium is initially cooled by the heat exchanger (6) and condensed into a liquid in the condenser (7). The liquid storage tank (8) circulates again through the working medium pump (9).

The condenser (7) is a known partition heat exchanger, and the refrigerant (7-1) is water or air.

The heating system consists of heat exchangers (6) and heat users (5). The exhaust steam at the outlet of the expander still has a relatively high temperature (60-120°C), and the heat is transferred to the heat medium through the heat exchanger (6), and the heat medium sends the heat to the heat user, and the heat medium after releasing heat flows back again Heat exchanger (6) absorbs heat.

Embodiment two:

Photovoltaic photothermal coupled heat and power cogeneration system uses PVT modules as preheaters and CPC modules as evaporators for solar heat collection and utilization. The number and series-parallel connection of single boards in PVT modules and CPC modules are determined according to the heat capacity, working fluid flow rate and system operating temperature and pressure parameters of the photovoltaic-thermal coupling cogeneration system, including but not limited to the arrangement shown in Figure 2 in the present invention.

After the organic working fluid is pressurized by the working fluid pump (9), it absorbs the heat from the back plate of the battery board through the PVT module (1), and the temperature initially rises, but it is still in a supercooled liquid state; Absorbing solar heat to collect heat, the temperature rises and vaporizes into high-temperature and high-pressure steam; the working medium steam becomes low-pressure steam after the work of the expander (3) drives the generator (4) to generate electricity; at this time, the steam still has a relatively high temperature, In 6), part of the heat is transferred to the heat medium, and then the condenser (7) fully releases the heat and condenses until the liquid is stored in the liquid storage tank (8) to complete a cycle.

The electric energy generated by the solar panel in the PVT module (1) and the electric energy generated by the expander (3) driving the generator (4) are used as the total electric energy output of the system.

The heat exchanger (6) is a partition-type heat exchanger, and the other side is the heat absorption process of the heat medium, and the heat medium transfers heat to the heat user (5) to achieve the purpose of heat supply.

The condenser (7) is a partition heat exchanger, and the refrigerant 7-1 is cooling water or air.

The invention combines photovoltaic power generation with low-temperature photothermal organic Rankine cycle power generation, uses the heat generated by photovoltaic power generation to preheat the working medium, reduces the heat collection area per unit electric power, and supplies heat while generating electricity. To make full use of solar energy resources, realize "temperature matching, cascade utilization", and improve the thermal efficiency and economy of the whole system.

This embodiment is only a preferred specific implementation of the present invention, but the scope of protection of the present invention is not limited thereto. Any skilled person in the technical field can easily think of changes or substitutions within the technical scope disclosed in the present invention. , should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (8)

1. A photovoltaic photothermal coupled heat and power cogeneration system, characterized in that it consists of a heat collection subsystem, a power generation subsystem, and a heat supply subsystem connected in series; The heat collection subsystem includes a photovoltaic photoelectric integrated component and a compound parabolic heat collector; The power generation sub-system is composed of an expander, a generator, a heat exchanger, a condenser, a liquid storage tank and a working medium pump in series; The heating subsystem consists of heat exchangers and heat users. 2. The system according to claim 1, characterized in that the integrated photovoltaic components are composed of solar panels and heat exchange components, and a plurality of integrated photovoltaic components are composed of integrated photovoltaic components through a series-parallel structure array of components. 3. The system according to claim 1, characterized in that, the plurality of compound parabolic heat collectors are composed of a compound parabolic heat collector array through a series-parallel structure. 4. The system according to claim 1, characterized in that, the electric energy of the photovoltaic photothermal coupled heat and power cogeneration system comes from the photovoltaic power generation of photovoltaic photoelectric integrated components and the power generation of generators. 5. A photovoltaic photothermal coupling heat and power cogeneration method using the system according to any one of claims 1-4, characterized in that the method comprises the following steps: S1, the working fluid is pressurized by the working fluid pump, and then the photovoltaic photoelectric integrated module absorbs the heat of the back plate of the battery board, so that the temperature of the working fluid is initially raised; S2, the working medium further absorbs solar energy heat collection through the compound parabolic heat collector assembly, so that the temperature is raised and vaporized into high-temperature and high-pressure steam; S3, the high-temperature and high-pressure steam of the working medium becomes low-pressure steam after the expander works to drive the generator to generate electricity; S4, the low-pressure steam of the working medium transfers part of the heat to the heat medium in the heat exchanger, and then fully releases heat through the condenser to condense to liquid and store it in the liquid storage tank, and then circulates again through the working medium pump. 6 . The method according to claim 5 , wherein the step S1 further comprises: transferring the heat generated by the solar cell to the working medium through the heat exchange component while generating electricity. 6 . 7. The method according to claim 5, characterized in that, the step S2 further comprises: using a compound paraboloid to condense light onto the heat-absorbing coating of the inner tube of the vacuum tube, and then the heat is transferred to the internal heat exchange component through the heat-absorbing coating Flowing working medium. 8. The method according to claim 5, characterized in that the step S4 further comprises: providing the low-pressure exhaust steam at the outlet of the expander to the heat supply user after passing through the heat exchanger.