A rural biomass solar complementary self-circulation heat supply system and method

Abstract

This application relates to the field of clean heating, and more particularly to a rural biomass-solar complementary self-circulating heating system and method. The system includes: a biomass heat source unit for burning biomass raw materials to generate heat; a solar heat source unit for absorbing solar energy to generate heat; a heat storage unit, whose inlet is fluidly connected to the outlets of the biomass and solar heat source units via a water supply pipeline; and a heat dissipation terminal unit, whose inlet is fluidly connected to the outlet of the heat storage unit, and whose outlet is fluidly connected to the inlets of the biomass and solar heat source units via a return water pipeline, thus forming a closed circulation loop together with the water supply pipeline. The water supply pipeline is laid at a higher height than the return water pipeline, allowing the fluid in the circulation loop to form natural circulation power based on the density difference between the hot and cold fluids, eliminating the need for a power circulation pump. This application can fully utilize local rural resources, reduce dependence on unstable external energy sources, and is easy to maintain.

Description

Technical Field

[0001] This application relates to the field of clean heating technology, and in particular to a rural biomass-solar complementary self-circulating heating system and method. Background Technology

[0002] The statements in this section are merely background information related to this application and do not necessarily constitute prior art.

[0003] Heating is a basic necessity for ensuring the well-being of rural residents during winter. However, rural areas in my country have long faced multiple challenges, including high heating costs, heavy pollution, and poor adaptability. Traditional coal-fired heating methods have high carbon emission intensity and cause serious air pollution. Clean heating policies such as "coal-to-electricity" and "coal-to-gas" implemented to control pollution have reduced pollution emissions to some extent, but new problems have emerged when implemented in rural areas: on the one hand, the relatively high prices of electricity and gas result in a heavy burden of heating operating costs for rural households; on the other hand, the poor stability of the power grid and insufficient coverage of gas pipelines in some remote rural areas pose a risk of frequent power outages or gas supply interruptions during the heating season, making it difficult to guarantee stable heating.

[0004] Rural areas possess abundant biomass resources (such as agricultural waste like straw and sawdust) and ample solar energy resources, providing a natural advantage for achieving low-cost, sustainable clean heating. Currently, existing technological solutions utilizing these resources mainly fall into two categories, but both have significant drawbacks: Category 1: Single biomass heating unit. This type of unit typically uses a biomass gasifier or combustion furnace as its core, heating circulating water by burning biomass feedstock, and relying on an electric circulation pump to drive the hot water circulation within the system to achieve heating. Its drawbacks are: 1. Reliance on external power: The circulating pump must rely on a stable power grid. Rural power grids, especially in remote areas, experience large voltage fluctuations and frequent power outages. Once a power outage occurs, the entire heating system immediately collapses and becomes inoperable.

[0005] 2. Poor heating stability: The equipment typically lacks effective heat storage units. When the biomass feedstock is exhausted or the furnace is shut down at night, the system cannot provide continuous heating, and the indoor temperature drops rapidly, resulting in a poor user experience.

[0006] 3. Complex maintenance and operation: Biomass stoves require users to manually clean the ash frequently (usually 1-2 times a day), and electrical components such as circulating water pumps also need to be inspected regularly, which requires high technical skills and time and energy from rural users.

[0007] The second type: Single solar heating system. This type of system heats water by collecting solar energy through solar collectors (such as vacuum tube collectors) installed on the roof, and also requires a circulating pump to transfer the heat indoors. Its drawbacks are: 1. Severely constrained by weather: Solar energy is intermittent and unstable, and cannot effectively collect heat on cloudy, rainy, snowy days and at night. It is necessary to rely on high-power electric auxiliary heating equipment to supplement the heat source, which not only leads to high operating costs, but also fails to completely get rid of the dependence on the unstable power grid.

[0008] 2. Limited resource utilization: The system failed to effectively utilize readily available local biomass resources in rural areas and relied entirely on commercial electricity when solar energy was insufficient, thus failing to achieve optimal complementary utilization of resources.

[0009] In summary, existing single-energy heating solutions, whether biomass or solar energy, have failed to effectively address the core pain points in rural areas regarding power supply reliability, heating stability, operational economy, and ease of operation. Therefore, there is an urgent need for an innovative heating technology that can fully utilize local rural resources, reduce dependence on unstable external energy sources, and is easy to maintain. Summary of the Invention

[0010] To overcome the shortcomings of the prior art, this application provides a rural biomass-solar complementary self-circulating heating system and method, which can make full use of local rural resources, get rid of dependence on unstable external energy sources, and is easy to maintain, thus better meeting the winter heating needs of rural areas.

[0011] To achieve the above objectives, this application provides the following technical solution: In a first aspect, a rural biomass-solar complementary self-circulating heating system is provided, the system comprising: A biomass heat source unit is used to generate heat by burning biomass raw materials; A solar thermal power unit is used to generate heat by absorbing solar energy; The thermal storage unit has its inlet connected to the outlets of the biomass heat source unit and the solar heat source unit via a water supply pipeline. The heat dissipation terminal unit has its liquid inlet in fluid communication with the liquid outlet of the heat storage unit, and its liquid outlet in fluid communication with the liquid inlets of the biomass heat source unit and the solar heat source unit through the return water pipeline, thereby forming a closed circulation loop together with the water supply pipeline. The water supply pipeline is laid at a higher height than the return pipeline, allowing the fluid in the circulation loop to form a natural circulation force based on the density difference between the hot and cold fluids, without the need for a power circulation pump.

[0012] Furthermore, the system also includes a control unit, which includes a heat source switching valve. The heat source switching valve is located at the liquid inlet pipe of the heat storage unit and is configured to: Detect the outlet temperature of the solar thermal source unit; When the outlet temperature of the solar thermal source unit is not lower than the first preset temperature threshold, the circulation loop is controlled to connect with the solar thermal source unit. When the outlet temperature of the solar thermal source unit is lower than the first preset temperature threshold, the circulation loop is controlled to connect with the biomass thermal source unit.

[0013] Furthermore, the control unit also includes an intelligent temperature control module, which is configured to: Detect indoor temperature; When the indoor temperature is lower than the second preset temperature threshold, the biomass heat source unit is controlled to start or continue to operate. When the indoor temperature is higher than the third preset temperature threshold, the biomass heat source unit is controlled to shut down or stop operating.

[0014] Furthermore, the heat storage unit is a phase change heat storage tank, which is filled with a phase change material with a phase change temperature of 55°C to 60°C.

[0015] Furthermore, the biomass heat source unit is a biomass gasifier, which includes an automatic ash removal device. The automatic ash removal device is configured to automatically perform ash removal operation when the amount of ash accumulated in the ash hopper of the biomass gasifier reaches a preset capacity.

[0016] Furthermore, the biomass gasifier also includes a large-capacity feed hopper, the volume of which is designed so that a single addition of biomass feed can sustain the operation of the biomass gasifier for 8 to 12 hours.

[0017] Furthermore, the solar heat source unit is a vacuum tube solar collector, and the inner wall of its vacuum tube is coated with an anti-scaling coating.

[0018] Furthermore, the heat dissipation terminal unit is a low flow resistance heat sink.

[0019] Furthermore, an air vent valve is installed at the highest point of the water supply pipeline.

[0020] Secondly, a method for rural biomass-solar complementary self-circulating heating is also provided, employing the rural biomass-solar complementary self-circulating heating system as described above, the method comprising: The fluid in the circulation loop is heated by a biomass heat source unit and / or a solar heat source unit; Utilizing the density difference between the heated fluid and the cooled fluid, as well as the height difference between the water supply pipe and the return pipe, the fluid is driven to circulate naturally in the circulation loop, flowing sequentially through the heat storage unit for heat storage and the heat dissipation terminal unit for heat dissipation. The switching between the biomass heat source unit and the solar heat source unit is controlled according to the outlet temperature of the solar heat source unit to achieve complementary heating.

[0021] Compared with the prior art, the beneficial effects of this application are as follows: 1. High reliability: The system does not rely on an external power grid, has no moving parts (such as water pumps), has a low failure rate, and can operate stably in harsh rural environments.

[0022] 2. High stability: Dual heat source synergy and phase change thermal storage technology ensure continuous and stable heat output, small indoor temperature fluctuations, and high user comfort.

[0023] 3. High economic efficiency: It has extremely low operating costs and maintenance costs, and makes full use of local resources with almost zero cost, providing rural users with an affordable clean heating solution.

[0024] 4. High environmental friendliness: It replaces high-carbon-emission bulk coal, makes efficient use of agricultural waste (straw), reduces environmental pollution caused by burning straw, and achieves low-carbon and clean heating.

[0025] 5. High adaptability: Its modular design and simplified operation and maintenance enable it to be quickly and flexibly adapted to different house types, climates and resource conditions in China's vast rural areas.

[0026] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings.

[0027] The present application will be further described below with reference to the accompanying drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the basic structure of a rural biomass-solar complementary self-circulating heating system according to an embodiment of this application; Figure 2 This is a schematic diagram of the overall structure of a rural biomass-solar complementary self-circulating heating system according to an embodiment of this application; Figure 3This is a schematic diagram of the working process of a rural biomass solar complementary self-circulating heating system according to an embodiment of this application. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] like Figure 1 As shown, one embodiment of this application provides a rural biomass-solar complementary self-circulating heating system, the system comprising: A biomass heat source unit is used to generate heat by burning biomass raw materials; A solar thermal power unit is used to generate heat by absorbing solar energy; The thermal storage unit has its inlet connected to the outlets of the biomass heat source unit and the solar heat source unit via a water supply pipeline. The heat dissipation terminal unit has its liquid inlet in fluid communication with the liquid outlet of the heat storage unit, and its liquid outlet in fluid communication with the liquid inlets of the biomass heat source unit and the solar heat source unit through the return water pipeline, thereby forming a closed circulation loop together with the water supply pipeline. The water supply pipeline is laid at a higher height than the return pipeline, allowing the fluid in the circulation loop to form a natural circulation force based on the density difference between the hot and cold fluids, without the need for a power circulation pump.

[0032] The aforementioned technical solution achieves "energy autonomy" and "zero-power circulation" for the system. By utilizing fluid density differences and pipeline height differences to create natural circulation power, the system completely eliminates its dependence on unstable external power grids and electric circulation pumps. This directly addresses the core pain point of heating interruptions caused by power outages in rural areas, while simultaneously achieving zero energy consumption (saving approximately 500 kWh of electricity annually) and maintenance-free operation of the circulation pump, significantly reducing the system's operating and maintenance costs. This solution fully utilizes local rural resources, eliminates dependence on unstable external energy sources, and better meets the winter heating needs of rural areas.

[0033] This technical solution develops a self-circulating heating structure that utilizes fluid density differences to achieve pump-free autonomous circulation, eliminating dependence on external power sources. The solution employs a pump-free self-circulating structure design, leveraging the density difference between hot and cold water, combined with the height difference between the supply and return water pipes, to achieve autonomous circulation of the heating system. This eliminates reliance on external power sources and circulation pumps, effectively reducing energy consumption and maintenance costs.

[0034] As a preferred technical solution, the system further includes a control unit, which includes a heat source switching valve. The heat source switching valve is located at the liquid inlet pipe of the thermal storage unit and is configured to: detect the liquid outlet temperature of the solar thermal source unit; when the liquid outlet temperature of the solar thermal source unit is not lower than a first preset temperature threshold, control the circulation loop to connect with the solar thermal source unit; and when the liquid outlet temperature of the solar thermal source unit is lower than the first preset temperature threshold, control the circulation loop to connect with the biomass thermal source unit.

[0035] This embodiment presents the control logic of the heat source switching valve, which realizes an intelligent collaborative heating mode of "solar energy priority, biomass backup". Its technical effect is to maximize the use of free solar energy resources, automatically activating the biomass heat source only when solar energy is insufficient (such as on cloudy or rainy days, or at night). This not only significantly reduces the consumption of biomass raw materials (from 2-3 tons per household per year to ≤1.5 tons), thereby controlling the monthly operating cost below 150 yuan, but also ensures heating continuity through automatic switching, improving the system's economy and automation level.

[0036] As a preferred technical solution, the control unit further includes an intelligent temperature control module, which is configured to: detect the indoor temperature; when the indoor temperature is lower than a second preset temperature threshold, control the biomass heat source unit to start or continue operating; and when the indoor temperature is higher than a third preset temperature threshold, control the biomass heat source unit to shut down or stop operating.

[0037] This embodiment illustrates the control logic of the intelligent temperature control module, which achieves "on-demand heating" and "constant temperature comfort." By monitoring the indoor temperature and automatically controlling the start and stop of the biomass gasification furnace (starting at 16℃ and stopping at 20℃), the system can automatically maintain the room temperature within a comfortable range of 16-20℃, with fluctuations ≤ ±1℃. This avoids the overheating and fuel waste caused by a sudden drop in room temperature after furnace shutdown or continued combustion, as in traditional solutions, greatly improving heating comfort and energy efficiency. In specific implementation, the intelligent temperature control module (low-power supply) is wired to the gasification furnace / heat source switching valve.

[0038] This embodiment adopts intelligent low-power control: the temperature control module is powered by a rechargeable battery (with a single charge lasting ≥30 days, or powered by a solar cell), automatically switches the heat source and controls the start and stop of the gasifier, requiring no manual intervention and lowering the barrier to entry for use.

[0039] In practice, the electromagnetic drive of the heat source switching valve can also be powered by solar cells. In fact, the solenoid valve only consumes power when switching and hardly consumes power at other times.

[0040] As a preferred technical solution, the heat storage unit is a phase change heat storage tank, which is filled with a phase change material with a phase change temperature of 55°C to 60°C.

[0041] The core effect of the phase change thermal storage tank in this embodiment is to achieve both "thermal energy buffering" and "continuous heating." Phase change material (PCM) undergoes a phase change at 55-60℃, storing and releasing a large amount of heat, with a heat storage density (≥200MJ / m³) far exceeding that of ordinary insulated water tanks. This allows the system to continuously release heat from the storage tank for several hours when the heat source is interrupted (e.g., at night, or after biomass combustion), solving the problem of unstable heating in a single heat source system and ensuring stable heating around the clock.

[0042] In extreme situations such as continuous rainy or snowy weather, or temporary interruptions in the supply of biomass raw materials, the system in this embodiment can maintain heating for a period of time by relying on the heat storage capacity of the phase change thermal storage tank. This design enhances the robustness and reliability of the system. For example, under outdoor conditions of -5°C, the system can maintain an indoor temperature of no less than 16°C for up to 12 hours solely by releasing heat from the phase change thermal storage tank.

[0043] As a preferred technical solution, the biomass heat source unit is a biomass gasifier, which includes an automatic ash removal device. The automatic ash removal device is configured to automatically perform ash removal operation when the amount of ash accumulated in the ash hopper of the biomass gasifier reaches a preset capacity.

[0044] In this embodiment, the biomass heat source unit uses a biomass gasifier, which is also equipped with an automatic ash cleaning device, thus simplifying maintenance. This device reduces the ash cleaning operation from the traditional 1-2 times per day to an automatic cycle every 3-5 days. This significantly reduces the user's daily maintenance burden, making the system more suitable for rural users with limited maintenance capabilities and lowering the barrier to entry.

[0045] As a preferred technical solution, the biomass gasifier also includes a large-capacity raw material feed hopper, the volume of which is designed so that a single addition of biomass raw material can sustain the operation of the biomass gasifier for 8 to 12 hours.

[0046] This embodiment of the biomass gasification furnace adopts a large-capacity feed hopper, which results in "easy operation". The large-capacity feed hopper (10-15kg feed at a time) allows the system to run continuously for 8-12 hours, reducing the user's feeding frequency from 2-3 times a day to 1-2 times a day. This simplifies daily operation, improves the ease of use of the system, and is especially suitable for elderly users in rural areas.

[0047] As a preferred technical solution, the solar heat source unit is a vacuum tube solar collector, and the inner wall of its vacuum tube is coated with an anti-scaling coating.

[0048] In this embodiment, the solar thermal source unit uses a vacuum tube solar collector, which is equipped with an anti-scaling coating. The anti-scaling coating is durable and maintenance-free. The anti-scaling coating can effectively cope with the potentially poor water quality in rural areas, extending the cleaning cycle of the vacuum tube from frequent maintenance to 3-6 months without cleaning, reducing the maintenance requirements of the system and ensuring the long-term stability of the heat collection efficiency.

[0049] In specific implementation, this application embodiment constructs a complementary mode of "biomass gasification furnace + solar collector". Biomass provides the base load, solar energy supplements the heat, and with the phase change thermal storage tank, stable heating is achieved around the clock (room temperature maintained at 16-20℃). This embodiment also optimizes the structural design, simplifies the operation and maintenance process (ash cleaning cycle extended to 3-5 days, collectors do not require frequent cleaning), and is suitable for rural users. This solution can locally dispose of rural agricultural waste (straw, sawdust), reduce biomass raw material consumption (average annual consumption per household ≤ 1.5 tons), improve solar energy utilization, and achieve an average monthly operating cost of ≤ 150 yuan per household. This solution effectively realizes the complementary heating logic of "biomass gasification furnace + solar collector": solar energy takes priority, biomass provides a backup, and with the phase change thermal storage tank, it solves the problem of insufficient stability of a single heat source and can achieve continuous heating around the clock.

[0050] As a preferred technical solution, the heat dissipation terminal unit is a low flow resistance heat sink.

[0051] In this embodiment, the heat dissipation terminal unit employs a low-flow-resistance radiator, whose structure is designed to adapt to the fluid flow rate under the natural circulation dynamics. The role of the low-flow-resistance radiator is "adaptive optimization," its structure specifically designed for the low flow rate (0.2-0.3 m / s) characteristic of the natural circulation system, ensuring heat dissipation efficiency (≥100W / ℃) under limited circulation dynamics, and guaranteeing the smoothness and effectiveness of the entire self-circulation system. In specific implementation, the low-flow-resistance radiator and piping are adapted to the low flow rate characteristics of the self-circulation, ensuring both heat dissipation efficiency and smooth circulation.

[0052] As a preferred technical solution, an air vent valve is installed at the highest point of the water supply pipeline.

[0053] In this embodiment, an air vent valve is installed at the highest point of the water supply pipeline. The function of the air vent valve is to "ensure reliability". The air vent valve can automatically discharge the air accumulated in the pipeline, effectively preventing the occurrence of "air blockage" and ensuring that the natural circulation power can continuously and smoothly drive the fluid flow, thereby improving the reliability of system operation.

[0054] In some preferred embodiments, the self-circulating pipeline adopts a "gradual expansion" design, with an inlet diameter of 25mm and an outlet diameter of 32mm, reducing flow resistance; the gasifier heat exchange coil adopts a spiral structure to increase the heat exchange area; the tilt angle of the solar collector can be adjusted according to the local latitude (35° for 30°-40°N, and 40° for 40°-50°N) to improve heat collection efficiency.

[0055] In some preferred embodiments, the thermal storage unit can also use an insulated water tank for thermal storage. The cost of an insulated water tank is 40%-50% lower than that of a phase change thermal storage tank, and the structure is simpler, but the thermal storage density is lower (about 80MJ / m³), requiring an increase in the tank volume (from 200-300L to 500-600L), making it suitable for rural bungalows where installation space requirements are not high.

[0056] In some preferred embodiments, the biomass heat source unit can also be a biomass pellet stove. Biomass pellet stoves have high fuel molding density and more complete combustion (thermal efficiency ≥80%), do not require raw material crushing, and are more convenient to operate. However, the cost of pellet fuel is 30%-40% higher than that of loose straw (increasing the average annual cost per household by 500-800 yuan), making them suitable for rural areas where biomass pellets are readily available.

[0057] In some preferred embodiments, the solar thermal source unit may also employ a flat-plate collector. Flat-plate collectors offer stronger resistance to hail and freezing (suitable for temperatures below -30°C) and are easier to maintain, but their heat collection efficiency is 5%-10% lower than that of vacuum tubes, requiring an increase in the heat collection area (from 2-4㎡ to 3-5㎡). They are suitable for rural areas with severe winters and frequent hail.

[0058] The above-mentioned preferred alternatives (insulated water tank heat storage, biomass pellet furnace, flat plate collector, etc.) can all achieve the invention's purpose of "self-circulation, dual heat source complementarity, and rural adaptability." The only trade-off is in "cost-efficiency-adaptability scenario." The appropriate solution can be selected based on the specific rural area's resource conditions (biomass type, solar irradiance), climate characteristics, and user cost affordability.

[0059] The following are examples illustrating application scenario adaptation: ① Resource-rich rural areas (with abundant straw): The proposed solution (i.e., biomass gasification furnace + vacuum tube solar collector + phase change heat storage tank) should be given priority, as it has the lowest raw material cost; ② Rural areas in frigid regions (winter < -20℃): Adopt the alternative solution of "biomass pellet furnace + flat plate collector + insulated water tank" to improve cold resistance stability; ③ For rural areas with ample space (large courtyards): adopt an alternative solution of "gasifier + vacuum tube collector + insulated water tank" to reduce equipment costs; ④ Remote rural areas without power grid: By adopting the proposed solution (i.e., biomass gasification furnace + vacuum tube solar collector + phase change thermal storage tank), the dependence on electricity can be completely eliminated, and only the temperature control module needs to be charged periodically (with the assistance of a solar charger).

[0060] In the aforementioned rural biomass-solar complementary self-circulating heating system, the biomass heat source unit, solar heat source unit, thermal storage unit, heat dissipation terminal unit, and pipelines all adopt a modular design. This modular design and simplified operation and maintenance allow for quick and flexible adaptation to different house types, climates, and resource conditions in vast rural areas of China. The overall modular design of the system facilitates installation (two people can complete the installation in one day) and is well-suited to different rural house types (single-story houses, two-story buildings), eliminating the need for large-scale house renovations.

[0061] The system adopts a rural-adaptive optimized design: the automatic ash removal device extends the ash removal cycle to 3-5 days, the anti-scaling coating of the solar collector eliminates the need for frequent cleaning, and the large-capacity design of the raw material feed hopper reduces the frequency of replenishment, making it suitable for the operation capabilities of rural users.

[0062] The aforementioned "dual heat source complementarity + phase change thermal storage" scheme can save approximately 50% on fuel costs. In reality, the fuel cost savings are related to the ratio of solar energy to biomass. Theoretically, over-promoting solar energy can achieve savings of over 90%. Generally, a solar-to-biomass energy ratio of approximately 6:4 is reasonable, but this can vary significantly depending on local climate conditions and solar angle. Biomass is considered a zero-carbon fuel, and solar energy is a clean energy source; therefore, this scheme is a highly efficient and practical clean heating technology.

[0063] An embodiment of this application also provides a rural biomass-solar complementary self-circulating heating method, which employs the rural biomass-solar complementary self-circulating heating system as described above. The method includes the following steps: Heat source heating steps: Heating the fluid in the circulation loop through a biomass heat source unit and / or a solar heat source unit; Natural circulation step: Utilizing the density difference between the heated fluid and the cooled fluid, as well as the height difference between the water supply pipe and the return pipe, the fluid is driven to circulate naturally in the circulation loop, flowing sequentially through the heat storage unit for heat storage and the heat dissipation terminal unit for heat dissipation. Heat source switching steps: Based on the outlet temperature of the solar heat source unit, control the switching between the biomass heat source unit and the solar heat source unit to achieve complementary heating.

[0064] The above method effectively achieves "pump-free self-circulating heating" and "intelligent complementarity of dual heat sources," possessing technical advantages such as energy self-sufficiency, stable comfort, economic efficiency, and low maintenance.

[0065] In some preferred embodiments, the heat source switching step specifically includes: The solar thermal source unit is used preferentially for heating; When the outlet temperature of the solar thermal power unit is below 50°C, it automatically switches to heating using the biomass thermal power unit.

[0066] This embodiment clarifies the specific temperature threshold for the heat source switching step, limiting the switching temperature to 50°C. This effectively identifies the "optimal economic switching point." This temperature threshold is a concrete guarantee for realizing the "solar energy priority" principle, ensuring that solar energy is used preferentially while it still has value, and switching to biomass only when efficiency is low, thus achieving the best balance in terms of technology and economy.

[0067] In some preferred embodiments, the method further includes a temperature control step: Detect indoor temperature; When the indoor temperature is below 16°C, the biomass heat source unit is controlled to start or continue to operate. When the indoor temperature is higher than 20°C, the biomass heat source unit is controlled to shut down or stop operating.

[0068] This embodiment clarifies the specific temperature thresholds for the temperature control steps, limiting the control temperature to 16°C for startup and 20°C for shutdown. This effectively defines a "comfortable and energy-saving temperature range." This optimized temperature range ensures both human comfort and avoids unnecessary energy waste, serving as a core parameter guarantee for achieving constant temperature comfort and energy-saving operation.

[0069] To make the embodiments of this application clearer, the relevant terms in this embodiment will be further explained below.

[0070] Biomass gasification furnace: a core device that uses agricultural waste such as straw, sawdust, and dead branches in rural areas as raw materials to generate combustible gases (carbon monoxide and hydrogen) through incomplete combustion, and then releases heat through combustion in a burner to provide a basic heat source for the heating system.

[0071] Self-circulation technology: Based on the principle of fluid thermal expansion and contraction, it utilizes the density difference between hot and cold water to form a natural circulation force, eliminating the need for additional circulation pumps and enabling hot water to flow autonomously between collectors, storage tanks, and heat dissipation terminals, thereby reducing energy consumption and maintenance costs.

[0072] Phase change thermal storage tank: A thermal storage device with built-in phase change material (such as paraffin-based composite phase change material, phase change temperature 55-60℃), which can store heat when there is sufficient solar energy or when the biomass gasifier is running, and release heat when there is no heat source input to maintain heating stability.

[0073] Complementary heating: The biomass gasifier provides the base load (meeting 60%-70% of daily heating needs), while the solar collector provides the supplementary load (meeting 30%-40% of heating needs on sunny days). The two automatically switch their output ratios according to outdoor temperature and sunshine conditions, achieving a coordinated mode of "biomass-dominated on cloudy days and solar-assisted on sunny days".

[0074] Rural Adaptability Design: In view of the characteristics of unstable power supply, weak maintenance capabilities and abundant biomass resources in rural areas, the design adopts a simplified structure and convenient operation without external power supply, with an average maintenance cost of ≤50 yuan / year per household.

[0075] To make the above-mentioned rural biomass solar energy complementary self-circulating heating system and method clearer, the following will provide further explanation in conjunction with the above-mentioned preferred technical solutions.

[0076] The "Rural Biomass-Solar Complementary Self-Circulating Heating System" proposed in this application is based on an integrated design of "self-circulating pipeline + dual heat source complementarity + phase change thermal storage," achieving low-cost and stable heating in rural areas through pump-free circulation, heat source synergy, and thermal storage buffering. The following diagram illustrates this. Figure 2 System overall structure diagram; Figure 3 (System workflow diagram) Detailed explanation: 1. System core components and function definitions

[0077] In this embodiment, water is used as the heat medium. The liquid inlet is the water inlet, the liquid outlet is the water outlet, the liquid supply pipeline is the water supply pipeline, and the liquid return pipeline is the water return pipeline. In this embodiment, the water supply pipeline (5) is 5-10cm higher than the water return pipeline (6) to form a self-circulating power by utilizing the height difference and density difference. The air vent valve (7) is installed at the highest point of the water supply pipeline to discharge the air in the pipeline and avoid air blockage.

[0078] This embodiment uses computational-volume mechanics simulation to show that for ordinary insulation, with a heating area of ​​80-225 square meters, a water supply temperature of 60±5 degrees Celsius, a return water temperature of 35±5 degrees Celsius, and a height difference of 5-10 cm, the flow is relatively smooth without a circulation pump, with small eddies and sufficient power.

[0079] 2. System Workflow Reference Figure 3 As shown, the system achieves stable heating through four steps: "heat source acquisition - heat storage and buffering - self-circulation heat dissipation - intelligent switching". Its core relies on self-circulation power and the synergy of dual heat sources. The specific process is as follows: Step 1: Heat source acquisition and heating (corresponding to) Figure 3 (1-Heat Source Acquisition) Biomass heat source: After the user crushes the straw / wood chips, he puts them into the raw material feed hopper (11). The raw material falls naturally into the gasification chamber of the gasifier (1). After ignition, it generates combustible gas through incomplete combustion. The combustible gas is released by the burner and heats the circulating water in the heat exchange coil in the gasifier (the cold water flowing in from the return water pipe is heated to 60-70℃). The automatic ash removal device (2) monitors the amount of ash accumulated in the ash hopper in real time and automatically discharges ash after reaching the threshold.

[0080] Solar heat source: Vacuum tube solar collector (3) absorbs solar radiation energy and heats the circulating water in the collector (cold water flows in from the return water pipe and is heated to 50-60℃); the collector is coated with an anti-scaling coating, and can still maintain cleaning-free operation for 3-6 months when the water quality in rural areas is poor.

[0081] Heat source switching: The intelligent temperature control module (9) compares the outlet temperature of the solar collector with the set threshold (50℃) in real time: When the solar water temperature is ≥50℃, the heat source switching valve (10) automatically switches to the solar side and prioritizes solar heating; when the water temperature is <50℃ (cloudy or rainy days, night), it switches to the biomass gasification furnace side and the biomass provides heat.

[0082] Step 2: Self-circulating power generation (corresponding to) Figure 3 (2-Self-loop drive) The hot water (temperature 50-70℃) in the water supply pipeline (5) has a low density (about 980kg / m³), while the cold water (temperature 30-40℃) in the return water pipeline (6) has a high density (about 992kg / m³). Utilizing the density difference of "hot water rises and cold water sinks", combined with the height difference (5-10cm) between the supply water pipe and the return water pipe, a natural circulation force is formed, which pushes the hot water out of the collector / gasifier outlet, into the heat storage tank (4) through the supply water pipe, and then into the radiator (8). After heat dissipation, it becomes cold water and flows back to the heat source unit for reheating through the return water pipe. No circulation pump is required throughout the process.

[0083] The exhaust valve (7) at the highest point of the pipeline automatically discharges the air generated during the circulation process, avoiding air blockage that affects the circulation efficiency; the pipeline insulation layer reduces heat loss and ensures that the temperature drop during hot water transportation is ≤5℃.

[0084] Step 3: Heat storage, buffering, and heat dissipation (corresponding to...) Figure 3 (3-Heat Storage and Heat Dissipation) The heated water first enters the phase change heat storage tank (4) and transfers the heat to the phase change material inside the tank. After absorbing the heat, the phase change material changes from solid to liquid and stores the heat. When the heat source is interrupted (such as when the biomass raw materials are exhausted or there is no solar energy at night), the phase change material changes from liquid to solid and releases the heat, maintaining the water temperature inside the tank at ≥45℃ and ensuring the continuity of heat dissipation.

[0085] Hot water in the heat storage tank is transported to the low flow resistance radiators (8) in each room through branch pipes. The radiators dissipate heat into the room and raise the room temperature. The cooled water (temperature 30-40℃) after heat dissipation flows back to the heat source unit through the return water pipe to complete the circulation.

[0086] The intelligent temperature control module (9) collects the real-time indoor temperature: when the room temperature is <16℃, it controls the gasifier to run continuously (biomass side) or extends the solar energy access time; when the room temperature is >20℃, it controls the gasifier to shut down and only retains the heat storage tank to release heat to avoid overheating and waste.

[0087] Step 4: Intelligent Adjustment and Maintenance (corresponding to...) Figure 3 (4-Intelligent Adjustment and Maintenance) Raw material replenishment: After the gasifier has been running for 8-12 hours, when the raw material in the feed hopper is depleted, the intelligent temperature control module will issue an audible and visual prompt, and the user can replenish the raw material (10-15kg at a time, operation time ≤5 minutes). Ash removal operation: The automatic ash removal device completes automatic ash discharge every 3-5 days. Users only need to clean the ash collected in the ash hopper periodically (which can be used as farm fertilizer), without the need for professional tools; Freeze protection: In extreme low temperatures (< -10℃) during winter, add antifreeze (30%) to the circulating water to prevent the pipes from freezing and cracking; when the system is shut down, the residual hot water in the pipes can be drained through the drain valve for easy storage during winter.

[0088] for Figure 3 The workflow diagram is as follows: "1 - Biomass / Solar heat source acquisition and heating" → "2 - Density difference driven self-circulation" → "3 - Phase change thermal storage tank buffer → Low flow resistance radiator heat dissipation" → "4 - Intelligent temperature control and regulation + regular maintenance". Each step is connected by pipelines or signal links to form a closed loop. The "heat source switching" logic runs through steps 1-4, dynamically adjusting the heat source access according to the solar water temperature and room temperature to ensure both stability and energy saving.

[0089] Compared with the most similar "rural biomass heating stove" (i.e., a single biomass heating device, hereinafter referred to as Scheme 1) in related technologies, the core advantages of this application are as follows: 1. Eliminate dependence on external power supply and significantly reduce maintenance costs: Solution 1 requires an electric circulating pump (annual power consumption of 500kWh), and the pump is prone to failure (annual maintenance cost of 200-300 yuan); This application adopts a self-circulating design, with no pump and no additional energy consumption, and an annual maintenance cost of ≤50 yuan (only ash needs to be cleaned), and it can still operate normally during power outages; 2. Improved heating stability and comfort: Option 1 has no thermal storage module, and the room temperature drops below 10℃ within 2-3 hours after the boiler is shut down; This application maintains the room temperature at 16-20℃ with fluctuations of ≤±1℃ through solar complementary and phase change thermal storage, eliminating the need for frequent boiler restarts on cloudy or rainy days and at night, resulting in a better user experience; 3. Reduced raw material consumption and lower operating costs: Option 1 consumes 2-3 tons of biomass raw materials per household per year, with a monthly operating cost of 200-300 yuan; This application, combined with solar energy supplementation, reduces raw material consumption to ≤1.5 tons / year, with a monthly operating cost of ≤150 yuan, and also disposes of agricultural waste locally, resulting in significant environmental benefits. 4. Simpler operation and maintenance, suitable for rural scenarios: Solution 1 requires daily dust removal and frequent material replenishment (2-3 times a day); this application extends the dust removal cycle to 3-5 days, reduces the material replenishment frequency to once a day (or once every 12 hours), simplifies the operation process, and makes it easy for elderly people in rural areas to use; 5. Wider installation compatibility: Option 1 requires fixed installation in the kitchen, which has poor compatibility; this application has a modular design and can be installed in various locations such as courtyards and rooftops, which is compatible with common rural house types such as bungalows and two-story houses. No house structure modification is required, and the installation cycle is shortened by 50%.

[0090] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0091] The parts not mentioned in the above embodiments are the same as or can be implemented using existing technologies, and will not be further described here.

[0092] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A rural biomass-solar complementary self-circulating heating system, characterized in that, The system includes: A biomass heat source unit is used to generate heat by burning biomass raw materials; A solar thermal power unit is used to generate heat by absorbing solar energy; The thermal storage unit has its inlet connected to the outlets of the biomass heat source unit and the solar heat source unit via a liquid supply pipeline. The heat dissipation terminal unit has its liquid inlet in fluid communication with the liquid outlet of the heat storage unit, and its liquid outlet in fluid communication with the liquid inlets of the biomass heat source unit and the solar heat source unit through the liquid return pipeline, thereby forming a closed loop together with the liquid supply pipeline. The supply pipeline is laid at a higher height than the return pipeline, allowing the fluid in the circulation loop to form a natural circulation force based on the density difference between the hot and cold fluids, without the need for a power circulation pump.

2. The rural biomass-solar complementary self-circulating heating system according to claim 1, characterized in that, The system also includes a control unit, which includes a heat source switching valve. The heat source switching valve is located at the liquid inlet pipe of the thermal storage unit and is configured to: Detect the outlet temperature of the solar thermal source unit; When the outlet temperature of the solar thermal source unit is not lower than the first preset temperature threshold, the circulation loop is controlled to connect with the solar thermal source unit. When the outlet temperature of the solar thermal source unit is lower than the first preset temperature threshold, the circulation loop is controlled to connect with the biomass thermal source unit.

3. A rural biomass-solar complementary self-circulating heating system according to claim 2, characterized in that, The control unit further includes an intelligent temperature control module, which is configured to: Detect indoor temperature; When the indoor temperature is lower than the second preset temperature threshold, the biomass heat source unit is controlled to start or continue to operate. When the indoor temperature is higher than the third preset temperature threshold, the biomass heat source unit is controlled to shut down or stop operating.

4. A rural biomass-solar complementary self-circulating heating system according to claim 1, characterized in that, The heat storage unit is a phase change heat storage tank, which is filled with phase change material with a phase change temperature of 55°C to 60°C.

5. A rural biomass-solar complementary self-circulating heating system according to claim 1, characterized in that, The biomass heat source unit is a biomass gasifier, which includes an automatic ash removal device. The automatic ash removal device is configured to automatically perform ash removal operation when the amount of ash accumulated in the ash hopper of the biomass gasifier reaches a preset capacity.

6. A rural biomass-solar complementary self-circulating heating system according to claim 5, characterized in that, The biomass gasifier also includes a large-capacity feed hopper, the volume of which is designed so that a single addition of biomass feed can sustain the operation of the biomass gasifier for 8 to 12 hours.

7. A rural biomass-solar complementary self-circulating heating system according to claim 1, characterized in that, The solar thermal source unit is a vacuum tube solar collector, and the inner wall of its vacuum tube is coated with an anti-scaling coating.

8. A rural biomass-solar complementary self-circulating heating system according to claim 1, characterized in that, The heat dissipation terminal unit is a low flow resistance heat sink.

9. A rural biomass-solar complementary self-circulating heating system according to claim 1, characterized in that, An air vent valve is installed at the highest point of the liquid supply pipeline.

10. A method for rural biomass-solar complementary self-circulation heating, characterized in that, The method of using the rural biomass-solar complementary self-circulating heating system as described in any one of claims 1 to 9 includes: The fluid in the circulation loop is heated by a biomass heat source unit and / or a solar heat source unit; Utilizing the density difference between the heated fluid and the cooled fluid, as well as the height difference between the supply pipeline and the return pipeline, the fluid is driven to circulate naturally in the circulation loop, flowing sequentially through the heat storage unit for heat storage and the heat dissipation terminal unit for heat dissipation. The switching between the biomass heat source unit and the solar heat source unit is controlled according to the outlet temperature of the solar heat source unit to achieve complementary heating.

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