CN110822967A - Integral structure for adsorption type thermochemical energy storage and building heating - Google Patents

Abstract

The invention discloses an integrated structure for adsorption-type thermochemical energy storage and building heating, comprising a gas main inlet section, a valve, a gas inlet branch pipe section, an energy storage reaction bed, a gas outlet branch pipe section, a gas general outlet section, a steering The valve, the gas outdoor outlet section, the gas indoor outlet section, and the pipeline insulation layer, the present invention is used for heat storage and release in the gas-solid adsorption/desorption type energy storage reaction process. Each stage of the reaction bed is filled with solid reactants, and the surrounding of the pipeline is covered with thermal insulation materials to reduce heat loss during the reaction process. The invention includes a gas conveying pipeline and an energy storage reaction bed, which not only reduces the space volume of the heat storage and heat supply device, but also avoids the problems of local excessive adsorption and deliquescence of solid reactants, insufficient reaction, etc., and is beneficial to improve the gas-solid reaction process. The heat and mass transfer effect is improved, and the heat storage unit is directly combined with the gas transmission pipeline, the device is simple and reliable, and the feasibility of chemical heat storage in building heating or heating is improved.

Description

A monolithic structure for adsorption thermochemical energy storage and building heating

technical field

The invention relates to the technical field of thermochemical energy storage and building heating, in particular to an integrated structure for adsorption type thermochemical energy storage and building heating.

Background technique

Energy is the material basis of human activities. The continuous development and utilization of energy has promoted the development of human civilization. With the increasingly serious energy crisis, various measures for energy conservation and emission reduction are constantly being developed and applied. In today's energy consumption, building energy consumption is the most significant, accounting for about 1/3 of the country's total energy consumption. In order to use energy more reasonably and efficiently, it is extremely necessary to store and convert heat effectively. Compared with sensible and latent heat storage, thermochemical heat storage has a higher density and can be used for cross-seasonal heat storage with minimal heat loss. Combined with thermochemical heat storage methods, the solar thermal energy that is abundant in summer or clear daytime or the high temperature waste heat in industrial production is converted into chemical energy for storage, and the chemical energy is released and utilized in the form of thermal energy when heat is needed in the cold season, especially suitable for in the field of building energy efficiency. The principle of thermochemical heat storage is based on reversible chemical reactions accompanied by the absorption or release of energy during the reaction process.

Inorganic hydrated salt/steam, inorganic salt/ammonia, metal hydroxide/steam, etc. are currently common thermal storage working pairs for adsorption thermochemical energy storage. In particular, some hydrated salts have the advantages of simple reaction principle, cheap or easy preparation of heat storage materials, low requirements on pressure and temperature in the reaction process, clean and harmless reaction products, and no danger of inflammability and explosion. It is a very promising heat storage method. Taking the thermochemical energy storage reaction of a hydrated salt/water vapor system as an example, it utilizes a reversible gas-solid reaction to store and release heat in the heat storage (desorption) and heat release (adsorption) stages. The reaction equation is as follows:

In the heat storage stage of hydrated salt desorption, the salt hydrate is heated to form a crystalline salt with no water or part of the water molecule removed, and the energy is stored in the desorbed salt bed in the form of chemical potential energy; The adsorption process is to use water vapor or wet cold air to react with the desorbed crystalline salt, and the heat released during the adsorption process is provided to the user. At present, hydrated salt chemical heat storage has been proven to be reliable in building heating and heat recovery. Studies have shown that _LiOH.H2O , _{Ba ( OH ) 2.8H2O} , _LaCl3.7H2O , _MgCl2.6H2O , _CaCl2.6H2O , _{MgSO4.7H2O ,} and _SrBr2 Hydrated salts such as 6H ₂ O have high heat storage density and are very promising heat storage materials. However, hydrated salts have various problems during desorption or adsorption reactions. For example, a small thermal conductivity affects the heat transfer effect, resulting in a slow reaction process; during the adsorption process, the salt layer near the water vapor inlet section is prone to excessive water absorption, deliquescence or agglomeration, resulting in irreversible losses, reducing heat storage density and material usage. The deliquescence hydrated salt will cause a certain degree of corrosion to the reactor, while the salt layer far from the steam inlet cannot fully contact and react with the water vapor, thereby reducing the performance of the entire heat storage system.

Therefore, it is particularly important to design a reaction structure that is beneficial to adsorption thermochemical energy storage, and to solve the problems existing in thermochemical materials in the heat storage process to improve the heat and mass transfer effect during the reaction process and the performance of the heat storage system. The current research on adsorption thermochemical energy storage and utilization is only on a small scale in the laboratory, and mainly focuses on the heat storage material itself and the reaction mechanism, and there are few related research on the reaction structural unit and practical application demonstration. Invention patent application publication number CN107289803A, titled: "A university reactor for hydrated salt chemical energy storage", proposes that the heat storage material is divided into multiple reaction units by fins, the device has a simple structure and is easy to disassemble , not only can effectively avoid problems such as excessive adsorption and deliquescence of energy storage materials, but also improve the heat transfer effect under the action of fins. However, this heat storage reactor is only suitable for a closed system using water vapor for adsorption reaction, and an additional steam evaporation system is required, which increases the investment cost and the space required for use. In addition, the heat exchange fluid and the heat storage material are in contact with the heat storage material, and there is heat exchange loss. Invention patent application publication number CN105571208A, titled: "Adsorption bed structure" patent, proposes an adsorption bed structure for refrigeration, including a metal tube and a metal mesh tube set together, the two are coaxial, and are filled with adsorption. It is used to adsorb the refrigerant flowing in the metal mesh tube. The device realizes the heat exchange between the external medium and the refrigerant through the unit tube, and the packing density of the adsorbent is high. However, its essence is still to simply stack the adsorbent particles together, and there are still problems such as hindered heat and mass transfer process and uneven adsorption. Invention patent CN108548443A proposes a thermochemical adsorption heat storage device, which isolates and stores solid heat storage materials and reaction gases. In the heat storage stage, the device uses the absorbed solar thermal energy to heat the heat storage material, and the steam desorbed from the material is condensed and then flows into the liquid storage tank for cold storage; in the heat release stage, the vaporized liquid is introduced into the reaction bed by evaporation for adsorption and exothermic reaction. , the heat generated is supplied to the user after being acted by the heat exchanger. The device is safe and reliable, has high heat storage density and is easy to operate. However, this device has a complex system structure, numerous pipeline structures, high maintenance and operating costs, and the solid reactants are still filled in the same adsorber, which cannot avoid the problems of excessive adsorption and deliquescence of the solid reactants and insufficient reaction of other parts. .

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the existing technical defects, provide an integrated structure for adsorption thermochemical energy storage and building heating, and design a simple, compact and highly feasible thermochemical storage for building heating. able device. The technical solution for realizing the present invention is:

An integral structure for adsorption thermochemical energy storage and building heating, including a gas main inlet section, a valve, a gas inlet branch pipe section, an energy storage reaction bed, a gas outlet branch pipe section, a gas main outlet section, a steering valve, and a gas Outdoor outlet section, gas indoor outlet section, pipe insulation, bolts, threaded holes. The gas inlet and outlet sections are both cylindrical pipes, and the general inlet section is used to connect the dry hot air or wet cold air pipes provided from the outside.

The diameter of the part of the pipe of the reaction bed connected with the gas branch pipe section at both ends is not less than the diameter of the branch pipe section. In order to improve the utilization rate of the incoming gas and ensure that the solid reactant reacts with the gas as fully as possible, the diameter of the reaction bed pipeline is 1 to 4 times the diameter of the branch pipe section.

The length of each reaction bed pipeline part is generally not more than 50cm, or the length is not more than 6 times the diameter of the reaction bed pipeline, so as to ensure the mass transfer effect in the gas-solid reaction process and the circulation stability of the heat storage material.

The two ends of the reaction bed pipes filled with solid porous reactants are connected by bolts and can be disassembled for material withdrawal and packing. In addition, all the piping and the surrounding of the energy storage reaction bed unit are covered with thermal insulation layer to reduce the heat loss during the reaction process.

The number of reaction units can be selected by the number of open valves according to the actual heat load required in the room, thereby controlling the heat supply.

A diverting valve is installed in the main gas outlet section. According to the actual situation and needs, the reacted gas can be introduced indoors or outdoors through the diverting action. Generally speaking, in the heat storage stage, the hot air heats the solid reactants and the desorbed water vapor is discharged to the outdoor environment; in the heat release stage, the heat generated by the adsorption reaction is introduced into the room with the air for heating.

Each reaction bed unit operates in parallel, and the number and size of the reaction bed units are determined by the specific heat load scale of the building heating room. The integrated energy storage pipeline structure can be arranged in small households and large buildings in combination with solar heat collection devices or waste heat recovery devices. The entire heat storage device is arranged on the wall of the indoor building as a pipeline, which has high flexibility and feasibility.

Compared with the prior art, the present invention has significant advantages:

(1) An integral structure of the present invention for adsorption-type thermochemical energy storage and building heating divides the heat storage material into multiple reaction unit modules, and the amount of reactants in each reaction unit is small, avoiding the traditional The simple accumulation of thermochemical materials such as hydrated salts or hydroxides in the reaction vessel will cause problems such as partial deliquescence or agglomeration, and insufficient reaction, which is beneficial to the complete reaction.

(2) An integrated structure for adsorption thermochemical energy storage and building heating of the present invention integrates the heat storage unit and the gas transmission pipeline, does not require additional heat storage reactors and heat exchange equipment, and has a simple and compact overall structure , investment and maintenance costs are small.

(3) An integral structure of the present invention for adsorption-type thermochemical energy storage and building heating, whether in the stage of desorption heat storage or adsorption heat release, the incoming gas is in direct contact with the reactant, and the heat exchange is sufficient, The thermal efficiency of the reaction is improved.

(4) The present invention is an integrated structure for adsorption thermochemical energy storage and building heating. Combined with a solar heat collector or a waste heat recovery device, the integrated energy storage pipeline structure is arranged in small households and large buildings. The entire heat storage device is arranged on the wall of the indoor building as a pipeline, and the size and scale of the device structure can be designed according to the size of the indoor space; for a specific space, the number of open valves can also be used to select the reaction according to the current required heat load. The number of units, which in turn controls the heat supply. The monolithic structure has high flexibility and feasibility.

The present invention will be further described below in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is a schematic diagram of an integrated structure of the present invention for adsorption thermochemical energy storage and building heating;

2 is a two-dimensional schematic diagram of a single heat storage pipeline unit of a monolithic structure used for adsorption-type thermochemical energy storage and building heating according to the present invention;

3 is a three-dimensional cross-sectional view of a single heat storage pipeline unit of a monolithic structure used for adsorption-type thermochemical energy storage and building heating according to the present invention;

Detailed ways

Example 1:

As shown in Figure 1, Figure 2 and Figure 3, an integrated structure for adsorption thermochemical energy storage and building heating, including gas main inlet 1, valve 2, gas inlet branch pipe section 3, energy storage reaction bed 4, gas Outlet branch pipe section 5, gas main outlet section 6, diverting valve 7, gas outdoor outlet section 8, gas indoor outlet section 9, pipeline insulation layer 10, bolt 11, threaded hole 12. The gas inlet and outlet sections are both cylindrical pipes, and the general inlet section is used to connect the dry hot air or wet cold air pipes provided from the outside. The diameter of the reaction bed pipes connected with the gas branch pipe sections at both ends is not less than the diameter of the branch pipe sections. In order to improve the utilization rate of the incoming gas and ensure that the solid reactant reacts with the gas as fully as possible, the diameter of the reaction bed pipeline is 1 to 4 times the diameter of the branch pipe; The outflow of the desorbed steam and the heat release process will hinder the full reaction between the steam in the incoming flow and the reactants in the rear section of the reaction bed, and the solid particles in the front section of the reaction bed will be over-adsorbed and deliquescent. The length of each reaction bed pipeline is generally No more than 50cm, or no more than 6 times the diameter of the reaction bed pipeline, to ensure better mass transfer effect during the gas-solid reaction process; the two ends of the reaction bed pipeline filled with solid porous reactants have threaded holes 12, which are connected by bolts 11. , can be dismantled for reclaiming and packing; in addition, all pipelines and the surrounding of energy storage reaction bed 4 units are covered by thermal insulation layer 10 to reduce heat loss during the reaction process; after the gas after the reaction is converged in the gas total outlet section 6 , after the action of the steering valve 7, the airflow can be introduced indoors or outdoors according to the actual situation and needs; each reaction bed unit operates in parallel, and the number and size of the reaction bed units depend on the specific heat load scale of the building heating room. . The integrated energy storage pipeline structure can be arranged in small households and large buildings in combination with solar heat collection devices or waste heat recovery devices. The entire heat storage device is arranged on the wall of the indoor building as a pipeline, and the size and scale of the device structure can be designed according to the size of the indoor space; for a specific space, the number of open valves can also be used to select the reaction according to the current required heat load. The number of units, which in turn controls the heat supply. The monolithic structure has high flexibility and feasibility.

The working principle of an integrated structure for adsorption thermochemical energy storage and building heating of the present invention:

Taking SrBr ₂ ·6H ₂ O hydrated salt as the heat storage material as an example, the working process of energy storage and energy release of the integrated structure for adsorption thermochemical energy storage and building heating of the present invention is introduced. Experimental studies have shown that SrBr ₂ ·6H ₂ O can be desorbed to a large extent at around 80-90 °C, and its reversible reaction equation is:

1. Heat storage process: The dry hot air heated by the solar air collector or the industrial waste heat device is transported through the external pipeline, and flows into the gas inlet section 1 of the pipeline structure, and the opened valve 2 transports the hot air to each gas The inlet branch pipe section 3, and then to the energy storage reaction bed 4, the salt hydrate is heated and desorbed and water vapor is released, the temperature of the hot air after heating the reaction bed is lowered, and the mixed moist air formed by water vapor and dry air is in the gas total outlet section. 6 converges, and is discharged to the outdoor through the gas outdoor outlet section 8 under the action of the diverting valve 7. The thermal insulation layer 10 can reduce heat loss and promote the desorption reaction. This process continues until the end of the desorption reaction (the temperature or humidity of the outlet section can be used as a criterion for the end of the reaction: if the temperature or humidity of the outlet gas is almost no different from the inlet gas, the reaction has basically ended). So far, the desorption heat storage stage is completed, which is the process of converting thermal energy to chemical potential energy.

2. Heat release process: when the indoor temperature is low in winter or at night and it is necessary to obtain heat, the cold air provided by the outside (which can be pre-humidified) flows in from the main gas inlet section 1 of the reactor, and passes through the valve 2 and the inlet branch pipe section. After 3, the water vapor in the air and the reaction bed 4 carry out a hydration (adsorption) reaction, and the heat released by the reaction heats the air. 9 Introduce indoors to achieve the purpose of indoor heating. In addition, the number of reaction units can be selected by the number of open valves according to the current required heat load, thereby controlling the heat supply.

In a specific embodiment, still taking SrBr ₂ ·6H ₂ O hydrated salt as the heat storage material as an example, for a heating room with a length, width and height of 5m×5m×4m, the integral heat storage pipeline structure can be arranged along the room. The wall is arranged, the diameter of the pipeline part of the reaction bed is D=0.12m, the length L=22cm, and the diameter of the branch pipes at both ends is d=0.05m. The entire pipeline structure has N=10 reaction bed units and all valves are open for operation. SrBr ₂ ·6H ₂ O hydrated salt density ρ=2390kg/m3, molar mass M=0.3555kg/mol, reaction bed porosity ε=0.6, reaction heat q=337kJ/mol, then the total mass of hydrated salt in all reaction beds for:

The total heat stored in the desorption reaction is:

This heat can heat the room when necessary. That is, 108117kJ of heat can theoretically be stored and supplied. Of course, due to the heat loss in the actual operation process, the actual heat supply is generally slightly smaller than this value, but it can still show a good heat storage and heating effect. The simulation results show that in the process of energy storage, when the dry hot air velocity of each inlet branch pipe is u=0.05m/s and the temperature is T=85°C, the embodiment model takes about t=38h to complete the heat storage process, and the required heat The total flow of air is:

That is, the energy storage process can be completed only by supplying 134 m ³ of circulating hot air with a temperature of 85 °C, which is easy to achieve and feasible in practical applications.

To sum up, the integrated structure of the present invention for adsorption thermochemical energy storage and building heating is not only conducive to improving the heat and mass transfer effect in the gas-solid reaction process, but also directly connects the heat storage unit with the gas. Combined with the transmission pipeline, the device is simple and reliable, with high feasibility and flexibility, and can well apply chemical heat storage to building heating or heating.

Claims (6)

1. a monolithic structure for adsorption type thermochemical energy storage and building heating, characterized in that it comprises a gas general inlet section (1) for feeding air or other reactive gases, and the valve (2) is opened, and in the future The gas flow is introduced into the gas inlet branch pipe section (3) of each energy storage reaction unit, the energy storage reaction bed (4) for performing heat storage and heat release reactions, the gas outlet branch pipe section (5) for the outflow of the reacted gas, and the gas total outlet Section (6), for changing the steering valve (7) of the gas flow direction, the gas after the reaction is passed into the outdoor and indoor gas outlet section (8) and the gas indoor outlet section (9), and the pipeline structure is all It is a cylindrical duct in which the gas main inlet section (1) is connected to an external duct supplying dry hot air or moist cold air. 2. The monolithic structure for adsorption thermochemical energy storage and building heating according to claim 1, characterized in that the diameter of the reaction bed unit pipeline connected to the gas branch pipe section at both ends is not less than the diameter of the branch pipe section pipeline , in order to improve the utilization rate of the incoming gas and ensure that the solid reactant reacts with the gas as fully as possible, the diameter of the reaction bed pipeline is 1 to 4 times the diameter of the branch pipe. 3. the monolithic structure for adsorption thermochemical energy storage and building heating according to claim 1, it is characterized in that, the length of each reaction bed pipeline part is not more than 50cm, or the length is not more than 6 cm of the diameter of the reaction bed pipeline. times. 4. The monolithic structure for adsorption-type thermochemical energy storage and building heating according to claim 1, wherein the two ends of the reaction bed pipeline filled with the solid porous reactant have threaded holes (12), which are connected by bolts (12). 11) Connection, which can be dismantled for taking out materials and packing, in addition, all pipes and the surrounding of the energy storage reaction bed (4) unit are covered by a thermal insulation layer (10) to reduce heat loss during the reaction. 5. The monolithic structure for adsorption thermochemical energy storage and building heating according to claim 1, characterized in that, after the reacted gas converges in the gas total outlet section (6), it passes through the steering valve (7) After the effect, the airflow can be introduced indoors or outdoors according to the actual situation and needs. 6. The monolithic structure for adsorption-type thermochemical energy storage and building heating according to claim 1, wherein each reaction bed (4) unit operates in parallel, and the number and size of the reaction bed units depend on the building heating Depending on the size of the heat load required for the room, the integrated energy storage pipeline structure can be arranged in small households and large buildings in combination with solar heat collectors or waste heat recovery devices, and the entire heat storage device is arranged as a pipeline on the walls of indoor buildings.

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