Geothermal energy multi-mode coupling heating system and control method thereof

Abstract

The invention relates to a geothermal energy multi-mode coupling heating system and a control method thereof.The geothermal energy multi-mode coupling heating system comprises a water pump arranged in a geothermal energy water taking well; a primary side water inlet of the first heat exchanger is connected with a water pump outlet through a pipeline, and a primary side water outlet is connected with a primary side water inlet of the second heat exchanger; the secondary side water inlet receives low-temperature water returned by the user side, and the secondary side water outlet is connected with the high-temperature heat pump condenser side water inlet; a primary side water outlet of the second heat exchanger is connected with the recharge well; the secondary side water inlet is connected with the low-temperature heat pump evaporator side water outlet, and the secondary side water outlet is connected with the high-temperature heat pump evaporator side water inlet; a condenser-side water inlet of the low-temperature heat pump is connected in parallel with a user-side low-temperature water return pipeline, and a water outlet of the low-temperature heat pump is converged with a condenser-side water inlet of the high-temperature heat pump; the evaporator side water inlet is connected with the high-temperature heat pump evaporator side water outlet; a condenser side water outlet of the high-temperature heat pump is directly connected with a user side heat supply pipe network, and an evaporator side water outlet is connected with an evaporator side water inlet of the low-temperature heat pump.

Description

Technical Field

[0001] The present invention relates to a geothermal energy multi-mode coupling heating system and a control method thereof, and is applicable to the field of geothermal energy heating technology. Background Art

[0002] Geothermal energy has attracted considerable attention as a clean, renewable energy source. However, traditional geothermal heating systems have significant drawbacks. For one thing, temperature management is imprecise, making it difficult to cope with complex and changing heating demands. Furthermore, energy efficiency is low, and during peak winter heating loads, the system is prone to significant temperature fluctuations, resulting in significant heat waste.

[0003] An existing patent, publication number CN117869992A, discloses a heat exchange station zoned heating system that couples geothermal energy with a compression heat pump. While this system achieves zoned heating for both new and existing buildings and avoids thermal imbalances through the deployment of a primary grid water supply and return circulation unit, a radiator water supply and return circulation unit, a compression heat pump heating unit, and a floor heating water supply and return circulation unit, the system primarily relies on coupling the primary grid heat source with air / geothermal energy. This system lacks a deep cascade utilization of geothermal energy and lacks a multi-mode operation strategy tailored to seasonal load variations. This leaves room for improvement in heating stability and energy efficiency during severe cold spells.

[0004] Therefore, exploring an efficient heating system and control method that can intelligently adjust according to seasonal loads and deeply and cascade the use of geothermal energy has become a technical challenge that needs to be overcome urgently. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in view of the above-mentioned problems, a geothermal energy multi-mode coupling heating system and a control method thereof are provided.

[0006] The technical solution adopted by the present invention is: a geothermal energy multi-mode coupled heating system, comprising: a water pump, arranged in a geothermal energy water well, for extracting geothermal water; The first heat exchanger has a primary water inlet connected to the water pump outlet through a pipeline, and a primary water outlet connected to the primary water inlet of the second heat exchanger; a secondary water inlet receives low-temperature water returned from the user side, and a secondary water outlet connected to the high-temperature water inlet of the heat pump condenser; The second heat exchanger has its primary side water outlet connected to the recharge well for recharging the geothermal water after heat exchange; its secondary side water inlet is connected to the low-temperature heat pump evaporator side water outlet, and its secondary side water outlet is connected to the high-temperature heat pump evaporator side water inlet; The low-temperature heat pump has its condenser-side water inlet connected in parallel with the user-side low-temperature water return pipe, and its condenser-side water outlet merges with the high-temperature heat pump condenser-side water inlet; its evaporator-side water inlet is connected to the high-temperature heat pump evaporator-side water outlet, forming a heat pump working medium circulation loop; The high-temperature heat pump has its condenser-side water outlet directly connected to the user-side heating network, and its evaporator-side water outlet connected to the low-temperature heat pump evaporator-side water inlet.

[0007] Furthermore, it also includes: The geothermal well auxiliary heating unit includes a geothermal circulation pipeline and an evaporator. The geothermal circulation pipeline passes through the evaporator of the low-temperature heat pump and is used to extract shallow geothermal energy to supplement the heat source of the heat pump.

[0008] Furthermore, it also includes: The zoned heating control module is used to allocate heating circuits according to the user-side terminal type (radiator / floor heating): in the radiator circuit, the low-temperature water on the user side enters the first heat exchanger first for direct heat exchange; in the floor heating circuit, the low-temperature water on the user side is heated in stages by the low-temperature heat pump and the high-temperature heat pump before being supplied with heat.

[0009] Furthermore, a desander and a water softening device are arranged between the water pump and the first heat exchanger to filter impurities in the geothermal water and reduce the hardness; the high-temperature heat pump and the low-temperature heat pump form a two-stage compression system, in which the high-temperature heat pump is a high-pressure compressor and the low-temperature heat pump is a low-pressure compressor, and the two are connected in series through a working fluid pipeline.

[0010] Furthermore, the user-side heating network is divided into a high-temperature heating area (connected to the radiator) and a low-temperature heating area (connected to the floor heating coil). The high-temperature heating area directly receives hot water from the high-temperature heat pump condenser side, and the low-temperature heating area is coupled with the high-temperature heat pump heating circuit through the condensing heat exchanger for heat exchange.

[0011] A control method for a geothermal energy multi-mode coupled heating system, comprising: Seasonal mode judgment: switch to "severe cold season mode" or "early and late season mode" according to outdoor temperature and user-side load demand; Severe cold season mode: The water pump, first heat exchanger, second heat exchanger, low-temperature heat pump, and high-temperature heat pump are operated simultaneously; the geothermal water flow rate is the preset first flow rate (e.g., 160t / h), and the heat pump working fluid is compressed in two stages to achieve high-temperature heating; the floor heating circuit activates the geothermal well auxiliary heating unit, extracting geothermal energy through the evaporator; Initial and final mode: turn off the low-temperature heat pump and only run the high-temperature heat pump; the geothermal water flow is switched to the preset second flow (such as 80t / h), giving priority to meeting the high-temperature heating needs of the radiator; the floor heating circuit uses single-stage compression of the high-temperature heat pump to supply heat, and stops the geothermal well auxiliary heating.

[0012] Furthermore, the system monitors the parameters of each circuit in real time: the inlet and outlet temperatures of the secondary side of the first heat exchanger (target value 45℃ / 60℃); the inlet and outlet temperatures of the high-temperature heat pump condenser side (target value 60℃ / 70℃); the water supply temperature of the floor heating circuit (controlled to 40-50℃ through the condensing heat exchanger); and closed-loop control of the temperature of each zone is achieved by adjusting the water pump frequency, the heat pump compressor power and the geothermal circulation water pump flow.

[0013] The beneficial effects of the present invention are: efficient cascade utilization of geothermal energy: through the coupling of the first heat exchanger, the second heat exchanger and the high and low temperature heat pumps, multi-stage heat release of geothermal water is achieved, combined with the geothermal well auxiliary heating unit, the utilization rate of geothermal energy is improved, and the energy waste problem of the traditional system is solved.

[0014] Multi-mode intelligent adjustment: Switch the operating mode according to seasonal load. Dual heat pumps and dual heat sources cooperate to provide heating in severe cold periods, while a single heat pump operates efficiently in the early and late stages, ensuring heating stability in different environments and reducing operating costs.

[0015] Zoned heating is highly adaptable: heat is dynamically distributed based on the user-side terminal type (radiator / floor heating), with direct supply to high-temperature areas and step-by-step heating to low-temperature areas, avoiding thermal imbalance and improving heating comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the geothermal energy multi-mode coupling heating system in the embodiment.

[0017] 1. Water pump; 2. Desander; 3. First heat exchanger; 4. Second heat exchanger; 5. Low-temperature heat pump; 6. High-temperature heat pump; 7. Water intake well; 8. Recharge well. DETAILED DESCRIPTION

[0018] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0019] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0020] like Figure 1 As shown, this embodiment is a geothermal energy multi-mode coupled heating system, which includes a water pump 1, a desander 2, a first heat exchanger 3, a second heat exchanger 4, a low-temperature heat pump 5, a high-temperature heat pump 6, a geothermal well auxiliary heating unit (including a geothermal circulation pipeline and an evaporator) and a zoned heating control module.

[0021] In this example, water pump 1 is placed in geothermal water well 7. The water outlet of water pump 1 is connected to the primary water inlet of first heat exchanger 3 through desander 2 and water softening device. The primary water outlet of first heat exchanger 3 is connected to the primary water inlet of second heat exchanger 4. The primary water outlet of second heat exchanger 4 is connected to recharge well 8. Water pump 1 sequentially delivers high-temperature water from water well 7 to first heat exchanger 3 and second heat exchanger 4. After releasing heat in first heat exchanger 3 and second heat exchanger 4, the high-temperature water is delivered to recharge well 8.

[0022] In this embodiment, the water inlet on the secondary side of the first heat exchanger 3 is connected to the water outlet of the user's terminal equipment on the user side. The terminal equipment includes radiators, floor heating pipes, etc. The water outlet on the secondary side of the first heat exchanger 3 is connected to the water inlet on the condenser side of the high-temperature heat pump 6, and the water outlet on the condenser side of the high-temperature heat pump 6 is connected to the water inlet of the user's terminal equipment. The low-temperature water on the user side flows through the first heat exchanger 3 and the high-temperature heat pump 6 in sequence. After absorbing heat in the first heat exchanger 3 and the high-temperature heat pump 6, the low-temperature water is returned to the user side.

[0023] In this example, the condenser-side water inlet of low-temperature heat pump 5 is connected to the water outlet of the user terminal device, and the condenser-side water outlet of low-temperature heat pump 5 is connected to the condenser-side water inlet of high-temperature heat pump 6. Based on the instructions of the zoned heating control module, the low-temperature water on the user side can choose to directly enter the first heat exchanger 3 (radiator circuit) or first pass through the low-temperature heat pump 5 and then enter the high-temperature heat pump 6 (floor heating circuit). After absorbing heat at the low-temperature heat pump 5 and high-temperature heat pump 6, the low-temperature water is returned to the user side.

[0024] In this embodiment, the evaporator-side water outlet of the low-temperature heat pump 5 is connected to the secondary-side water inlet of the second heat exchanger 4, which in turn is connected to the evaporator-side water inlet of the high-temperature heat pump 6. The evaporator-side water outlet of the high-temperature heat pump 6 is connected to the evaporator-side water inlet of the low-temperature heat pump 5, forming a heat pump working medium circulation loop. The low-temperature heat transfer medium output from the evaporator-side water outlet of the low-temperature heat pump 5 flows sequentially through the second heat exchanger 4 and the high-temperature heat pump 6 before returning to the low-temperature heat pump 5. After absorbing heat and rising in temperature in the second heat exchanger 4, the low-temperature heat transfer medium releases heat in the high-temperature heat pump 6 and the low-temperature heat pump 5, transferring the heat energy absorbed from the second heat exchanger 4 to the high-temperature heat pump 6 and the low-temperature heat pump 5.

[0025] The geothermal circulation pipeline of the geothermal well auxiliary heating unit passes through the evaporator of the low-temperature heat pump 5. After the medium in the geothermal circulation pipeline absorbs shallow geothermal energy, it provides additional heat source for the low-temperature heat pump 5 through the evaporator, especially improving the heating capacity of the heat pump system during severe cold periods.

[0026] In this embodiment, the geothermal multi-mode coupled heating system needs to make the following preparations before starting: Equipment inspection: Conduct a comprehensive inspection of the heat energy conversion and processing equipment (heat exchanger, water pump, heat pump, etc.), water intake well 7, recharge well 8, user terminal equipment and geothermal well auxiliary heating unit to ensure that the equipment is not damaged, the connection is normal, all valves are in the initial closed state, the water level in the well is normal, the water quality meets the system operation requirements, and there is no water leakage in the terminal equipment.

[0027] Parameter setting: According to local climate conditions and historical heating data, preset the time range of the severe cold period and the initial and final period and the corresponding temperature thresholds. For example, when the average outdoor temperature is below -5°C for three consecutive days, it is determined to be a severe cold period, and when it is above 5°C, it is determined to be an initial and final period. Set the target values ​​of the inlet and outlet water temperature on the secondary side of the first heat exchanger 3 to 45°C / 60°C, the target values ​​of the inlet and outlet water temperature on the condenser side of the high-temperature heat pump 6 to 60°C / 70°C, and the target value of the water supply temperature of the floor heating circuit to 40-50°C. Set the preset first flow rate corresponding to the severe cold period system to 160t / h, and the preset second flow rate corresponding to the initial and final period system to 80t / h.

[0028] In this embodiment, the geothermal energy multi-mode coupled heating system is controlled in the following manner during the system operation phase: S1. Real-time monitoring of outdoor temperature: Based on the outdoor temperature and the preset temperature threshold, the current corresponding season mode is determined. The seasonal mode includes the severe cold period and the early and late cold periods.

[0029] S2. When it corresponds to a severe cold period: switch to full-load operation mode, start water pump 1, first heat exchanger 3, second heat exchanger 4, low-temperature heat pump 5, high-temperature heat pump 6 and geothermal circulation water pump, and at the same time open the water intake valve of water intake well 7 and the recharge valve of recharge well 8; monitor the inlet and outlet water temperature and flow of the first heat exchanger 3, low-temperature heat pump 5, and high-temperature heat pump 6 in real time, as well as the water temperature of the recharge well and the medium temperature of the geothermal circulation pipeline, and achieve closed-loop control of water temperature and flow by adjusting the operating power of the heat pump and water pump or the opening of the valve, so that the water temperature and flow are stabilized at the preset value. At this time, the radiator circuit directly supplies heat through the first heat exchanger 3 and high-temperature heat pump 6, and the floor heating circuit is heated by the two-stage compression cascade of low-temperature heat pump 5 and high-temperature heat pump 6. At the same time, the geothermal well auxiliary heating unit provides auxiliary heat to meet the high-load heating demand.

[0030] During the initial and final phases: Switch to low-load operation mode, start water pump 1, first heat exchanger 3, second heat exchanger 4, and high-temperature heat pump 6, shut down low-temperature heat pump 5 and the geothermal circulation water pump, and simultaneously open the water intake valve of water intake well 7 and the recharge valve of recharge well 8. Real-time monitoring is performed on the inlet and outlet water temperatures and flows of first heat exchanger 3 and high-temperature heat pump 6, as well as the recharge well water temperature. Closed-loop control of water temperature and flow is achieved by adjusting the operating power of the heat pumps and water pumps or the opening of their valves, stabilizing them at preset values. At this point, only high-temperature heat pump 6 is operating, giving priority to heating the radiator circuit. The floor heating circuit uses single-stage compression from high-temperature heat pump 6 to meet low-load demands and reduce energy consumption.

[0031] In this embodiment, when the geothermal energy multi-mode coupled heating system stops operating, such as when the heating period ends or the system needs maintenance, the system is stopped according to the following steps: First, turn off the high-temperature heat pump 6 and the low-temperature heat pump 5 (only turn off the high-temperature heat pump 6 in the initial and final stages); Shut down the heat exchanger, desander 2, water softener and geothermal circulation water pump; Close the water intake valve of the water intake well 7 and the recharging valve of the recharging well 8; Perform a comprehensive inspection and maintenance on the system to prepare for the next operation.

[0032] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

Claims

1. A geothermal energy multi-mode coupling heating system, characterized in that: include: A water pump is installed in the geothermal water well to extract geothermal water; The first heat exchanger has a primary water inlet connected to the water pump outlet through a pipeline, and a primary water outlet connected to the primary water inlet of the second heat exchanger; a secondary water inlet receives low-temperature water returned from the user side, and a secondary water outlet connected to the high-temperature water inlet of the heat pump condenser; The second heat exchanger has its primary side water outlet connected to the recharge well for recharging the geothermal water after heat exchange; its secondary side water inlet is connected to the low-temperature heat pump evaporator side water outlet, and its secondary side water outlet is connected to the high-temperature heat pump evaporator side water inlet; The low-temperature heat pump has its condenser-side water inlet connected in parallel with the user-side low-temperature water return pipe, and its condenser-side water outlet merges with the high-temperature heat pump condenser-side water inlet; The water inlet on the evaporator side is connected to the water outlet on the high-temperature heat pump evaporator side to form a heat pump working medium circulation loop; The high-temperature heat pump has its condenser-side water outlet directly connected to the user-side heating network, and its evaporator-side water outlet connected to the low-temperature heat pump evaporator-side water inlet.

2. The geothermal energy multi-mode coupling heating system according to claim 1, characterized in that: Also includes: The geothermal well auxiliary heating unit includes a geothermal circulation pipeline and an evaporator. The geothermal circulation pipeline passes through the evaporator of the low-temperature heat pump and is used to extract shallow geothermal energy to supplement the heat source of the heat pump.

3. The geothermal energy multi-mode coupling heating system according to claim 1, characterized in that: Also includes: The zoned heating control module is used to allocate the heating circuit according to the user-side terminal type: if the terminal type is a radiator: the low-temperature water on the user side enters the first heat exchanger for direct heat exchange first; if the terminal type is a loop: the low-temperature water on the user side is heated in stages by the low-temperature heat pump and the high-temperature heat pump before being heated.

4. The geothermal energy multi-mode coupled heating system according to claim 1, characterized in that: A desander and a water softening device are provided between the water pump and the first heat exchanger to filter impurities in the geothermal water and reduce the hardness; The high-temperature heat pump and the low-temperature heat pump form a two-stage compression system, wherein the high-temperature heat pump is a high-pressure stage compressor and the low-temperature heat pump is a low-pressure stage compressor, and the two are connected in series through a working fluid pipeline.

5. The geothermal energy multi-mode coupled heating system according to claim 1, characterized in that: The heating network on the user side is divided into a high-temperature heating area connected to the radiator and a low-temperature heating area connected to the floor heating coil. The high-temperature heating area directly receives hot water from the high-temperature heat pump condenser side, and the low-temperature heating area is coupled with the high-temperature heat pump heating circuit through the condensing heat exchanger for heat exchange.

6. A control method for a geothermal multi-mode coupled heating system according to any one of claims 1 to 5, characterized in that: include: Seasonal mode determination: Switch to "severe cold season mode" or "early to late season mode" based on outdoor temperature and user-side load demand; Severe cold season mode: Simultaneously operate the water pump, the first heat exchanger, the second heat exchanger, the low-temperature heat pump, and the high-temperature heat pump; The geothermal water flow rate is the preset first flow rate, and the heat pump working fluid achieves high-temperature heating through two-stage compression; The floor heating circuit activates the geothermal well auxiliary heating unit, extracting geothermal energy through the evaporator; Early and late stage mode: Turn off the low-temperature heat pump and only run the high-temperature heat pump; The geothermal water flow rate is switched to the preset second flow rate, giving priority to meeting the high-temperature heating demand of the radiator; The floor heating circuit uses a high-temperature heat pump with single-stage compression to provide heat, and stops the geothermal well for auxiliary heating.

7. The control method of the geothermal energy multi-mode coupling heating system according to claim 6, characterized in that: The system monitors each circuit parameter in real time: The inlet and outlet temperatures of the secondary side of the first heat exchanger are targeted at 45°C / 60°C. The inlet and outlet temperatures of the high-temperature heat pump condenser are targeted at 60°C / 70°C. The water supply temperature of the floor heating circuit is controlled at 40-50℃ through the condensing heat exchanger; By adjusting the water pump frequency, heat pump compressor power and geothermal circulation water pump flow, closed-loop control of the temperature of each zone is achieved.

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