Composite air-conditioning system based on shallow geothermal utilization and its working method

Abstract

The present invention discloses a composite air-conditioning system based on shallow geothermal utilization and its working method, which belongs to the field of air-conditioning technology. The composite air-conditioning system based on shallow geothermal utilization includes a user-side floor heating system, a user-side air-conditioning unit, a ground-source heat pump unit, an air-source heat pump unit, and a ground-source circulating water pump for free cooling. The ground-source heat pump unit, the air-source heat pump unit, and the ground-source circulating water pump for free cooling are respectively connected to the user-side floor heating supply and return water pipeline and the user-side air-conditioning supply and return water pipeline through pipelines. The three are arranged in parallel. The ground-source heat pump unit and the air-source heat pump unit are each provided with an independent circulating water pump. The supply and return water pipelines of the ground-source circulating water pump for free cooling are both connected to the ground-source side water supply pipeline, and an electric regulating valve is provided between the supply and return water pipelines of the ground-source circulating water pump for free cooling. The present invention can improve the energy efficiency of cooling and heating, realize free cooling in local time in summer, and has important significance for energy saving and consumption reduction.

Description

Technical Field

[0001] The present invention relates to a composite air-conditioning system based on shallow geothermal utilization, belonging to the technical field of air-conditioning. The present invention also relates to a working method of the composite air-conditioning system based on shallow geothermal utilization. Background Art

[0002] High-speed rail station waiting rooms are tall and large spaces with high passenger density. Frequent passenger flow in and out of the station results in significant wind leakage loads, resulting in higher overall heating and cooling performance than typical public buildings. High-speed rail station waiting rooms in cold and extremely cold regions typically use radiant floor heating in winter and modular air conditioning units in summer. Radiant cooling is rarely used in the summer, primarily because it easily creates condensation, requiring the installation of additional radiant cooling terminals and resulting in high initial investment.

[0003] Ground source heat pumps utilize the relatively stable geothermal resources in the shallow layers of the earth's surface to achieve efficient and energy-saving cooling and heating modes.

[0004] Therefore, research on the use of shallow geothermal energy to provide cooling and heating for the air-conditioning system of high-speed railway stations, so as to improve the energy efficiency of cooling and heating and realize free cooling in some parts of summer, is of great significance for energy conservation and consumption reduction. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a composite air-conditioning system based on shallow geothermal utilization.

[0006] The present invention is achieved through the following technical solutions: a composite air-conditioning system based on shallow geothermal utilization, including a user-side floor heating system and a user-side air-conditioning unit using circulating water for cooling, characterized in that it also includes a ground-source heat pump unit, an air-source heat pump unit, and a ground-source circulating water pump for free cooling. The ground-source heat pump unit is connected to a buried pipe arranged in a ground-source well through a pipeline. The ground-source heat pump unit, the air-source heat pump unit, and the ground-source circulating water pump for free cooling are respectively connected to the user-side floor heating supply and return pipes and the user-side air-conditioning supply and return pipes through pipelines. The three are arranged in parallel. A ground-source side water pump is provided on the ground-source side water supply pipe connected to the buried pipe. The ground-source heat pump unit is connected to the ground-source well through a pipeline. A user-side water pump connected in series is provided on the household side, and an air source heat pump circulating water pump connected in series is provided on the user side of the air source heat pump unit. The supply and return pipes of the ground source circulating water pump for free cooling are connected to the ground source side water supply pipe, and an electric regulating valve is provided between the supply and return pipes of the ground source circulating water pump for free cooling. Electric shut-off valves are provided on the pipes connecting the air source heat pump unit to the user-side floor heating supply and return pipes and on the pipes connecting the user-side air conditioning supply and return pipes. Electric shut-off valves are provided on the user-side floor heating supply and return pipes and the user-side air conditioning supply and return pipes. Electric shut-off valves are provided on the supply and return pipes of the ground source circulating water pump for free cooling.

[0007] In this invention, a free-cooling ground-source circulating water pump is added to a conventional geothermal heat pump system. The pump's supply and return pipes are connected to the ground-source water supply pipe, utilizing the ground-source well's natural free cooling source to provide indoor floor heating and air conditioning. An electric regulating valve is installed between the pump's supply and return pipes. Adjusting the valve's opening controls the water temperature during free radiant cooling, preventing condensation on the indoor radiant cooling floor. The ground source circulating water pump, ground source heat pump unit and air source heat pump unit for free cooling are connected to the air conditioning supply and return water pipes and floor heating supply and return water pipes on the user side. The three operate in parallel. By switching the electric shut-off valve, four operating modes can be realized: ground source free cooling, ground source heat pump unit (air source heat pump) + ground source free cooling, ground source heat pump unit air conditioning cooling + air source heat pump unit radiation cooling, and independent operation of ground source heat pump unit and air source heat pump unit. This can improve the energy efficiency of cooling and heating and achieve energy saving and consumption reduction.

[0008] Furthermore, temperature sensors are provided on the user-side floor heating supply and return pipes and the user-side air conditioning supply and return pipes, and a temperature sensor is also provided on the ground source side water supply pipe. Each temperature sensor is electrically connected to the control cabinet.

[0009] Furthermore, the opening of the electric regulating valve is controlled by the floor heating water temperature. By controlling the opening of the electric regulating valve according to the floor heating water temperature, the water temperature of the ground source free radiant cooling can be controlled, which can effectively prevent condensation on the indoor radiant cooling floor.

[0010] Furthermore, a temperature and humidity sensor is provided in the user's room, and the temperature and humidity sensor is electrically connected to the control cabinet.

[0011] Furthermore, heat meters are provided on the user-side floor heating water supply pipe and the user-side air conditioning water supply pipe, and a heat meter is also provided on the ground source side return water pipe. A temperature sensor is also provided in the ground source well, and each heat meter and the temperature sensor in the ground source well are electrically connected to the control cabinet. By providing a temperature sensor for monitoring ground temperature in the ground source well and a heat meter on the ground source side return water pipe, the heat intake and heat release of the ground source well in winter and summer can be collected, and the temperature of the ground source well can be monitored. Then, by adjusting the operating time of the ground source heat pump unit and the air source heat pump unit, the heat intake and heat release of the ground source well in winter and summer can be balanced, and the heat balance of the ground source well can be controlled. This can avoid heat and cold imbalance caused by the incomplete matching of heat and cold extracted from the ground source side in winter and summer when the ground source heat pump unit is running, which affects the normal use of the ground source heat pump system.

[0012] Furthermore, the ground source heat pump unit and the air source heat pump unit are both two groups arranged in parallel.

[0013] Furthermore, the ground source side water pump, the user side water pump, and the air source heat pump circulating water pump are all two units arranged in parallel.

[0014] The present invention also provides a method for operating the aforementioned composite air-conditioning system based on shallow geothermal utilization, the technical solution of which is as follows: in summer cooling, there are four operating modes, including:

[0015] Free ground source cooling mode: the ground source side water pump and the free cooling ground source circulating water pump are turned on, and the free cooling ground source circulating water pump directly supplies water to the user side floor heating water supply pipe, and the indoor cooling is provided by floor heating radiation. The floor heating return water is transported to the ground source side water supply pipe through the user side floor heating return water pipe; when the indoor dew point temperature T0 is greater than the ground source side water supply temperature T1, the electric regulating valve is turned on, and the mixing amount of hot and cold water is adjusted by controlling the opening of the electric regulating valve, so that the floor heating water supply temperature T3 is greater than the dew point temperature T0;

[0016] Or the ground source side water pump and the free cooling ground source circulating water pump are turned on, and the free cooling ground source circulating water pump directly supplies water to the user side air conditioning water supply pipe, and the user side air conditioning unit provides cooling to the room, and the air conditioning return water is transported back to the buried pipe through the user side air conditioning return water pipe;

[0017] Ground source heat pump unit and air source heat pump unit supplement ground source free cooling mode: when the ground source side water supply temperature T1 is less than 25℃, the ground source heat pump unit and air source heat pump unit are used to supplement the ground source free cooling gap, and the ground source heat pump unit is used to supplement cooling first. When the ground source heat pump unit cannot meet the supplementary cooling, the air source heat pump unit is started to supplement cooling; the ground source heat pump unit, the ground source side water pump, the user side water pump, and the ground source circulating water pump for free cooling are turned on, and the ground source circulating water pump for free cooling directly supplies water to the user side floor heating water supply pipe, and the floor heating radiation is used to cool the room, and the floor heating return water is passed through The user-side floor heating return water pipe is transported to the ground source side water supply pipe and mixed with the ground source side circulating water before entering the ground source heat pump unit. The cold water produced by the ground source heat pump unit is pressurized and circulated by the user-side water pump and enters the indoor air-conditioning unit through the user-side air-conditioning water supply pipe. The air-conditioning return water flows back to the ground source heat pump unit through the user-side air-conditioning return water pipe; when the air source heat pump unit and the ground source heat pump unit are operated in parallel, the air-conditioning circulating water is pressurized by the air source heat pump circulating water pump and enters the air source heat pump unit for cooling, then enters the indoor air-conditioning unit through the user-side air-conditioning water supply pipe to cool the room, and then flows back to the air source heat pump unit through the user-side air-conditioning return water pipe;

[0018] Ground source heat pump unit air conditioning cooling, air source heat pump unit radiation cooling mode: When the ground source side water supply temperature T1>25℃, the ground source heat pump unit is used to generate low-temperature water to cool the user side air conditioning unit, and the air source heat pump unit is used to cool the user side floor heating system;

[0019] Independent operation mode of ground source heat pump unit and air source heat pump unit: The ground source heat pump unit and air source heat pump unit operate independently. When the heat intake and heat release of the ground source well are unbalanced in winter and summer, the operation time of the ground source heat pump unit can be adjusted by adjusting the operation time of the air source heat pump unit, so as to balance the heat intake and heat release on the ground source side.

[0020] Furthermore, when the ground source heat pump unit and the air source heat pump unit are operated independently, the cooling load of the air source heat pump unit is 30% of the total cooling load.

[0021] Furthermore, during winter heating, the circulating water in the indoor floor heating pipes is transported by the floor heating return pipe on the user side, enters the ground source heat pump unit and the air source heat pump unit for heating, and is then transported to the indoor floor heating pipes through the floor heating water supply pipe.

[0022] The beneficial effects of the present invention are: (1) Floor heating radiation cooling can utilize a high temperature (20°C) cold source, which is highly compatible with the water supply temperature of the ground source well. On the basis of the traditional ground source heat pump system, the present invention adds a ground source circulating water pump for free ground source cooling. By connecting the supply and return pipes of the ground source circulating water pump for free cooling with the ground source side water supply pipe, the natural free cold source of the ground source well is used to cool the indoor floor heating and air conditioning, realizing the use of free cold source for cooling, greatly saving the cooling operation cost. At the same time, in order to solve the problem that radiant cooling is prone to condensation, an electric regulating valve is set between the supply and return pipes of the ground source circulating water pump for free cooling, By adjusting the opening of the electric regulating valve to control the water supply temperature of the ground source free radiation cooling, condensation on the indoor radiation cooling floor is prevented. The free cooling mode of the present invention can be added to the traditional ground source heat pump system, with small renovation work and low investment, which can greatly save the cooling operation cost; the supply and return pipes of the ground source circulating water pump for free cooling are connected to the ground source side water supply pipe, which has the advantage that the ground source circulating water pump for free cooling and the ground source side water pump run in series, but do not affect each other in terms of flow rate. The ground source side water pump can also meet the ground source side circulating water supply demand of the ground source heat pump unit while providing free cooling. The system is simple and easy to control;

[0023] (2) The present invention can realize four summer cooling operation modes: free ground source cooling, ground source heat pump unit (air source heat pump) + free ground source cooling, ground source heat pump unit air conditioning cooling + air source heat pump unit radiation cooling, and independent operation of ground source heat pump unit and air source heat pump unit. These four modes realize priority free cooling. When free cooling cannot meet the cooling load, the ground source heat pump unit and the air source heat pump unit are turned on in sequence to provide supplementary cooling. When the ground source water temperature is too high to provide free cooling, the ground source heat pump unit is used to provide cooling for the air conditioner, and the air source heat pump unit is used to provide radiation cooling for the floor heating. If there is an imbalance in the heat and cold of the ground source well, the ground source heat pump unit and the air source heat pump unit can be operated independently under partial load, and the heat and cold balance of the ground source well can be adjusted by their respective operating time. In the ground-source heat pump unit air conditioning cooling + air-source heat pump unit radiant cooling mode, the low-temperature water (around 7°C) produced by the more efficient ground-source heat pump unit is not only used for cooling the air-conditioning unit, but can also be used for dehumidification of the indoor environment. The high-temperature water (around 20°C) produced by the air-source heat pump unit is used for floor heating radiant cooling. Compared with the traditional air-source heat pump unit 7°C air conditioning cooling, the evaporation temperature is greatly reduced, and the cooling energy saving is over 30%;

[0024] (3) The present invention adds an air source heat pump system to the traditional single ground source heat pump system, and can operate the ground source heat pump unit and the air source heat pump unit according to demand. According to the characteristic that the cooling and heating loads are lower than 70% in most periods, the ground source heat pump is set at 70% and the air source heat pump is set at 30%. Compared with the system with only ground source heat pumps, investment is saved. By measuring the heat intake and heat release of the ground source well in winter and summer and monitoring the temperature of the ground source well, a control strategy for achieving the cooling and heat balance of the ground source well is proposed. By adjusting the duration of the air source heat pump unit, the heat intake and heat release of the ground source well in winter and summer are balanced, solving the problem of the ground source heat pump system's effect attenuating with the increase of usage time. The user-side circulating water pumps of the ground source heat pump unit and the air source heat pump unit in the present invention are independently set, which is more conducive to the hydraulic balance of the system operation. Independent water pumps can be selected according to their respective operating water volume requirements, and the user-side water systems do not interfere with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the composite air-conditioning system based on shallow geothermal utilization according to the present invention;

[0026] In the figure, 1. Ground source heat pump unit, 2. Air source heat pump unit, 3. Ground source side water pump, 4. User side water pump, 5. Air source heat pump circulating water pump, 6. Ground source circulating water pump for free cooling, 7. Ground source heat meter, 8. Air conditioning heat meter, 9. Floor heating heat meter, 10. Buried pipe, 11. Ground source well temperature sensor, 12. Ground source side water supply temperature sensor, 13. Air conditioning water supply temperature sensor, 14. Floor heating water supply temperature sensor, 15. Air conditioning return water temperature sensor, 16. Floor heating return water temperature sensor, 17. Indoor temperature and humidity sensor, 18. Outdoor temperature and humidity sensor, 19. Control cabinet, 20. Ground source side water supply pipe, 21. Ground source side return water pipe;

[0027] V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, V12, and V13 are electric shut-off valves, and V11 is an electric regulating valve;

[0028] The dotted lines in the figure are the control lines connecting the cold and hot source hosts, water pumps, electric valves, temperature sensors, etc. with the control cabinet. DETAILED DESCRIPTION

[0029] The present invention will be further described below by way of non-limiting embodiments with reference to the accompanying drawings:

[0030] Taking the cooling and heating of the high-speed railway station air-conditioning system as an example, a composite air-conditioning system based on shallow geothermal utilization is proposed.

[0031] As shown in the attached figure, a composite air-conditioning system based on shallow geothermal utilization is provided, wherein a user-side floor heating system and a user-side air-conditioning unit using circulating water cooling are provided on the user side, and further comprising a ground-source heat pump unit 1, an air-source heat pump unit 2, and a ground-source circulating water pump 6 for free cooling. The ground-source heat pump unit 1 comprises two units arranged in parallel, and the ground-source heat pump unit 1 is connected to a buried pipe 10 arranged in a ground-source well via a pipeline. Two ground-source side water pumps 3 are arranged in parallel on the ground-source side water supply pipeline 20 connected to the buried pipe 10, forming a conventional ground-source heat pump system. The air-source heat pump unit 2 is also arranged in parallel. The ground-source heat pump unit 1, the air-source heat pump unit 2, and the ground-source circulating water pump 6 for free cooling are all connected to the user-side floor heating supply and return pipes and the user-side air-conditioning supply and return pipes respectively through pipelines, and the three are arranged in parallel. The user-side floor heating water supply pipe is equipped with an electric shutoff valve V8, a floor heating water temperature sensor 14, and a floor heating heat meter 9. The user-side air conditioning water supply pipe is equipped with an electric shutoff valve V7, an air conditioning water temperature sensor 13, and an air conditioning heat meter 8. A connecting pipe is provided between the user-side floor heating water supply pipe and the user-side air conditioning water supply pipe. This connecting pipe is equipped with an electric shutoff valve V12, which can switch the ground source heat pump unit 1 to supply water to the user-side floor heating water supply pipe or the user-side air conditioning water supply pipe. The user-side floor heating return water pipe is equipped with an electric shutoff valve V10 and a floor heating return water temperature sensor 16. The user-side air conditioning return water pipe is equipped with an electric shutoff valve V9 and an air conditioning return water temperature sensor 15. A connecting pipe is provided between the user-side floor heating return water pipe and the user-side air conditioning return water pipe. This connecting pipe is equipped with an electric shutoff valve V13, which can control the flow direction of the floor heating return water. The ground-source heat pump unit 1 and the air-source heat pump unit 2 are each independently equipped with a user-side circulating water pump. The ground-source heat pump unit 1 is equipped with two parallel user-side water pumps 4 on the user-side air conditioning return water pipe, while the air-source heat pump unit 2 is equipped with two parallel air-source heat pump circulating water pumps 5 on the user-side. The air-source heat pump circulating water pumps 5 are installed on the return water pipe of the air-source heat pump unit 2. The air-source heat pump circulating water pumps 5 are connected to the user-side floor heating return water pipe and the air conditioning return water pipe through pipes, and the two pipes are respectively equipped with electric shut-off valves V3 and V4. The water supply pipe of the air-source heat pump unit 2 is divided into two routes, connected to the user-side air conditioning water supply pipe and the user-side floor heating water supply pipe, and the two pipes are respectively equipped with electric shut-off valves V5 and V6.The supply and return pipes of the free cooling ground-source circulating water pump 6 are both connected to the ground-source side water supply pipe 20. The supply pipe of the free cooling ground-source circulating water pump 6 is connected to the user-side floor heating water supply pipe and is connected to the user-side air conditioning water supply pipe through an electric shut-off valve V12. The return pipe of the free cooling ground-source circulating water pump 6 is connected to the user-side floor heating return pipe. The supply pipe of the free cooling ground-source circulating water pump 6 is provided with an electric shut-off valve V2, and its return pipe is provided with an electric shut-off valve V1. An electric regulating valve V11 is provided between the supply and return pipes of the free cooling ground-source circulating water pump 6. A ground-source side water supply temperature sensor 12 is provided on the ground-source side water supply pipe 20, a ground-source heat meter 7 is provided on the ground-source side return pipe 21, and a ground-source well temperature sensor 11 is provided in the ground-source well for monitoring the ground-source well temperature. An indoor temperature and humidity sensor 17 is provided indoors, and an outdoor temperature and humidity sensor 18 is provided outdoors. Each ground-source heat pump unit, each air-source heat pump unit, each heat meter, each temperature sensor, each temperature and humidity sensor, each water pump, and each electrically controlled valve are connected to the control cabinet 19 via control lines. Based on usage requirements, the control cabinet 19 controls the opening and closing of the electrically operated shut-off valve, the opening of the regulating valve, the start and stop of each water pump, the number of ground-source heat pump units and air-source heat pump units in operation, and collects temperature and cooling and heating quantities, thereby achieving control of the entire air-conditioning system.

[0032] The working method of the present invention is:

[0033] (1) Cooling operation

[0034] The present invention has four operating modes for summer cooling: free ground source cooling, ground source heat pump unit (air source heat pump) + free ground source cooling, ground source heat pump unit air conditioning cooling + air source heat pump unit radiant cooling, and independent operation of ground source heat pump unit and air source heat pump unit. The following are four operating modes:

[0035] (1) Free ground cooling:

[0036] For example, the indoor ambient temperature of a high-speed rail station is set at 28°C, and the minimum temperature difference for radiant cooling is 3°C. During free radiant cooling, the water temperature T1 measured by the ground source water supply temperature sensor 12 must be below 25°C for effective radiant cooling. During the initial cooling phase of the ground source heat pump system, the ground source water supply temperature is generally below 25°C, thus meeting the radiant cooling requirements. Electric shut-off valves V1, V2, V8, and V10 are opened, while electric shut-off valves V3, V4, V5, V6, V7, and V9 are closed. The ground source water pump 3 and the free cooling ground source circulating water pump 6 are turned on. The circulating water in the buried pipe 10, after cooling underground, is pressurized by the ground source water pump 3 and the free cooling ground source circulating water pump 6 and then enters the high-speed rail station floor heating pipe from the floor heating pipe supply port. The water is then transported back to the buried pipe 10 through the floor heating return port, achieving free radiant cooling with the ground source acting as the direct cooling source and the floor heating pipe acting as the cooling terminal. When using radiation cooling, if the temperature of the cold source is lower than the dew point temperature of the indoor environment, condensation water will form on the indoor floor. To solve this problem, the temperature and humidity of the indoor environment are measured by the indoor temperature and humidity sensor 17, and the temperature and humidity values ​​are transmitted to the control cabinet 19. The indoor dew point temperature T0 is calculated, and the ground source side water supply temperature sensor 12 can measure the ground source water supply temperature T1. When T0> T1, the electric regulating valve V11 is opened to mix the water supply on the ground source side with the return water of the floor heating pipe. The amount of mixed water is adjusted by adjusting the opening of the electric regulating valve V11. The opening of the electric regulating valve V11 is controlled by the value T3 measured by the floor heating water supply temperature sensor 14 to ensure that T3> T0, thereby effectively preventing condensation on the indoor radiation cooling floor.

[0037] After the winter heating heat extraction, the ground source side water supply temperature is generally 12℃ to 15℃ in early summer. The water temperature is relatively low. In the initial stage of cooling, it is also possible to consider directly using the ground source free cold source to supply cold water to the indoor air-conditioning units for cooling, so there is no need to worry about condensation. The electric shut-off valves V1, V2, V7, and V9 are opened, and the electric shut-off valves V3, V4, V5, V6, V8, and V10 are closed. The ground source side water pump 3 and the free cooling ground source circulating water pump 6 are turned on. After cooling underground, the circulating water in the buried pipe 10 is pressurized by the ground source side water pump 3 and the free cooling ground source circulating water pump 6 and enters the high-speed railway station air-conditioning unit from the air-conditioning water supply port to circulate and supply cooling to the high-speed railway station. The water is then transported back to the buried pipe 10 through the air-conditioning return port by the pipeline, realizing that the ground source serves as a direct cold source and the air-conditioning unit serves as the cooling terminal for free cooling.

[0038] (2) Ground source heat pump unit (air source heat pump) + ground source free cooling

[0039] In this mode, when free ground-source cooling cannot meet the indoor cooling load and the temperature T1 measured by the ground-source water supply temperature sensor 12 is less than 25°C, ground-source heat pump unit 1 and air-source heat pump unit 2 are operated to supplement the free ground-source cooling. Ground-source heat pump units are more energy-efficient and energy-efficient than air-source heat pump units. Therefore, ground-source heat pump unit 1 is prioritized for supplementary cooling. If ground-source heat pump unit 1 cannot meet the indoor cooling load, air-source heat pump unit 2 is activated. Electric shut-off valves V1, V2, V7, V8, V9, and V10 are opened, while electric shut-off valves V3, V4, V5, and V6 are closed. Ground-source water pump 3, user-side water pump 4, and free-cooling ground-source circulating water pump 6 are activated, and ground-source heat pump unit 1 is turned on. If ground-source heat pump unit 1 cannot meet the indoor cooling load after activation, electric shut-off valves V4 and V5 are opened, air-source heat pump circulating water pump 5 is turned on, and air-source heat pump unit 2 is turned on. After cooling underground, the circulating water in buried pipe 10 is pressurized by ground-source pump 3 and the free cooling ground-source circulating water pump 6, entering the high-speed railway station's floor heating pipes through the floor heating pipe supply port. It is then piped back through the floor heating return port and returns to the ground-source pump 3's supply pipe, where it mixes with the ground-source circulating water before entering geothermal heat pump unit 1. Geothermal heat pump unit 1 dissipates heat and cools the ground-source circulating water. The resulting cold water is pressurized by user-side pump 4 and circulated through the air conditioning water supply port to the indoor air conditioning unit, cooling the room before returning to geothermal heat pump unit 1 through the air conditioning return port and pipelines. Air-source heat pump unit 2 operates in parallel with geothermal heat pump unit 1. The air conditioning circulating water is pressurized by air-source heat pump circulating water pump 5 and enters air-source heat pump unit 2. After cooling, it enters the indoor air conditioning unit through the air conditioning water supply port and returns to air-source heat pump unit 2 through the air conditioning return port and pipelines.

[0040] (3) Ground source heat pump unit air conditioning cooling + air source heat pump unit radiation cooling

[0041] When the temperature T1 measured by the ground-source water supply temperature sensor 12 exceeds 25°C, directly using ground-source circulating water for radiant cooling is ineffective. The advantage of radiant cooling is that it can use high-temperature water for cooling, resulting in higher energy efficiency for the refrigeration unit and significant energy savings. Therefore, in this case, the high-temperature water (around 20°C) produced by air-source heat pump unit 2 can be used for radiant cooling of the floor heating pipes, while the low-temperature water (around 7°C) produced by ground-source heat pump unit 1 can be used for cooling the air conditioning units. Electric shut-off valves V3, V6, V7, V8, V9, and V10 are opened, and ground-source water pump 3, user-side water pump 4, air-source heat pump circulating water pump 5, ground-source heat pump unit 1, and air-source heat pump unit 2 are turned on. Ground-source heat pump unit 1 serves as the cold source for the indoor air conditioning unit, dissipating heat and cooling to the ground-source circulating water. The resulting cold water is pressurized and circulated by user-side water pump 4, entering the indoor air conditioning unit through the air conditioning water supply port, cooling the indoor temperature, and then flowing back to the ground-source heat pump unit through the air conditioning return port and pipelines. Air-source heat pump unit 2 serves as the cold source for floor heating radiant cooling. The floor heating circulating water is pressurized by air-source heat pump circulating water pump 5, enters air-source heat pump unit 2, and is cooled. It then flows through the floor heating water supply port into the indoor floor heating pipe, cooling the indoor temperature, and then flows back to air-source heat pump unit 2 through the floor heating return port and pipelines.

[0042] (4) The ground source heat pump unit and the air source heat pump unit operate independently

[0043] The energy efficiency of a ground source heat pump unit is higher than that of an air source heat pump unit. In order to save energy, it is generally preferred to operate the ground source heat pump unit independently. If only the ground source heat pump unit is operated, the heat and cooling extracted from the ground source side in winter and summer are not completely matched, which can easily cause a heat and cold imbalance. In long-term operation, the temperature of the circulating water in the buried pipe may be lower in winter or higher in summer, affecting the normal use of the ground source heat pump system. To solve this problem, a ground source heat pump unit and an air source heat pump unit are used for combined operation. The heat intake and heat release on the ground source side in winter and summer are recorded by the ground source heat meter 7. If there is a significant imbalance, the operation time of the ground source heat pump unit is adjusted by adjusting the operation time of the air source heat pump unit 2, thereby balancing the heat intake and heat release on the ground source side. The ground source heat pump system has high energy efficiency and high initial investment. The cooling and heating load is below 70% most of the time, and it is fully loaded only a very few times. The ground source heat pump unit and the air source heat pump unit are used for combined operation. The air source heat pump unit with a ratio of about 30% has little impact on the overall energy efficiency and can also reduce investment.

[0044] (2) Heating operation

[0045] During winter heating, the electric shut-off valves V4, V6, V8, and V10 are opened, and the electric shut-off valves V1, V2, V3, V5, V7, and V9 are closed. The ground source heat pump unit 1, the air source heat pump unit 2, the ground source side water pump 3, the user side water pump 4, and the air source heat pump circulating water pump 5 are turned on. The ground source side water pump 3 pressurizes the ground source circulating water, which is transported into the ground source heat pump unit 1 through the pipeline. After the ground source heat pump unit 1 absorbs the heat of the ground source circulating water, the ground source side circulating water is transported back to the buried pipe 10 through the pipeline for heating; the circulating water of the indoor floor heating pipe is transported by the floor heating return pipe, and is divided into two routes to enter the user side water pump 4 and the air source heat pump circulating water pump 5 for pressurization, and then enters the ground source heat pump unit 1 and the air source heat pump unit 2 for heating, and then is transported to the indoor floor heating pipe through the floor heating water supply pipe. The user-side water pump 4 is a user circulating water pump selected according to the flow rate of the ground source heat pump unit 1, and the air source heat pump circulating water pump 5 is a user circulating water pump selected according to the flow rate of the air source heat pump unit 2. The user-side water pump 4 and the air source heat pump circulating water pump 5 operate in parallel and are connected in series with the ground source heat pump unit 1 and the air source heat pump unit 2 respectively.

[0046] (3) Intelligent control

[0047] In the present invention, according to the use requirements, the control cabinet 19 is used to control the opening and closing of the electric shut-off valve, the opening of the regulating valve, the start and stop of each water pump, the number of ground source heat pump units and air source heat pump units in operation, and the temperature and cold and heat amounts are collected to achieve control of the entire air-conditioning system.

[0048] (1) The indoor temperature and humidity sensor 17 measures the indoor temperature TS and humidity d. The temperature and humidity values ​​are transmitted to the control cabinet 19 to calculate the indoor dew point temperature T0. For example, the maximum temperature of the indoor floor heating pipe radiation cooling water temperature is set at 25°C. The ground source side water supply temperature sensor 12 measures the ground source water supply temperature T1, and the floor heating water supply temperature sensor 14 measures the value T3. In summer cooling operation, the operation ratio of the cold source is controlled according to the value of the indoor temperature TS. Taking the waiting room of the high-speed railway station as an example, the indoor temperature is controlled at 28°C. In order to save energy, the ground source free cooling is used first. If the ground source free cooling is not sufficient, the ground source heat pump unit is turned on. If the ground source heat pump unit is not sufficient, the air source heat pump unit is turned on to supplement. When T1 < 25°C, the ground source free cooling mode is started. The value of T3 is controlled by controlling the opening of the electric regulating valve V11 to ensure that T3 > T0 to prevent condensation.

[0049] (2) Winter heating is controlled by the control cabinet 19, which controls the ground source heat pump unit 1 and the air source heat pump unit 2. The load ratio and the number of running units of the ground source heat pump unit 1 and the air source heat pump unit 2 are controlled by the value of the indoor temperature TS. Taking the waiting room of the high-speed railway station as an example, the control is based on 17℃. The energy efficiency of the ground source heat pump unit is much higher than that of the air source heat pump unit in winter. The ground source heat pump unit is operated first. If the ground source heat pump unit does not meet the heat load, the air source heat pump unit will be used as a supplement. The ground source heat pump unit is protected from freezing in winter by monitoring the temperature value of T1. For example, T1 should be set to be greater than 6℃, otherwise the ground source heat pump unit will stop running.

[0050] (3) The ground source heat meter 7 can measure the heat intake in winter and heat release in summer on the ground source side, heat intake Q1, heat release Q2, and the ground source well temperature sensor 11 can record the ground source well soil temperature T4. Compare the heat intake Q1 and heat release Q2 in the heating season and the cooling season. If the deviation between Q1 and Q2 exceeds 15%, the control cabinet 19 calculates the indoor cooling or heating capacity corresponding to the deviation value, and adjusts the operating time of the air source heat pump unit in winter or summer according to the deviated cooling or heating capacity to eliminate the imbalance between heat intake and heat release. The operating time of the air source heat pump unit should be adjusted in combination with the energy efficiency of the air source heat pump unit corresponding to the ambient temperature, indoor load and other factors. For example, if the heat intake Q1 is greater than the heat release Q2 (the deviation is greater than 15%), This indicates that the operation of ground source heat pump units and free ground source cooling should be increased in summer. Except when the cooling capacity of ground source heat pump units and free ground source cooling rooms does not meet the indoor load, ground source heat pump units and free ground source cooling should be operated first at other times. In winter, the use of air source heat pump units should be appropriately increased. The time for which air source heat pump units need to be operated first can be calculated based on the offset calorific value. Taking into account the low energy efficiency of air source heat pump units in low temperature environments, the use of air source heat pump units can be increased at the beginning and end of heating, and the heat extraction from ground source wells can be reduced at this stage. The temperature T4 of the ground source well soil can be compared at the same time each year. If there is basically no significant change at the same time each year and it is within a reasonable range, it means that the ground source well can achieve a good balance between cold and hot in winter and summer. If the temperature rises or falls significantly year by year, it is necessary to adjust the operation time of the air source heat pump units to adjust the cold and hot balance.

[0051] The other parts of this embodiment are all existing technologies and will not be described in detail here.

Claims

1. A composite air-conditioning system based on shallow geothermal utilization, comprising a user-side floor heating system and a user-side air-conditioning unit using circulating water cooling, characterized by: The ground source heat pump unit (1), the air source heat pump unit (2), and the ground source circulating water pump (6) for free cooling are also included. The ground source heat pump unit (1) is connected to the buried pipe (10) set in the ground source well through a pipeline. The ground source heat pump unit (1), the air source heat pump unit (2), and the ground source circulating water pump (6) for free cooling are respectively connected to the user side floor heating supply and return pipes and the user side air conditioning supply and return pipes through pipelines. The three are arranged in parallel. The ground source side water supply pipe connected to the buried pipe (10) is provided with a ground source side water pump (3). The ground source heat pump unit (1) is provided with a user side water pump (4) connected in series with the ground source side water pump (4) on the user side. The air source heat pump unit (2) An air source heat pump circulating water pump (5) connected in series with the user side is provided, the supply and return pipes of the free cooling ground source circulating water pump (6) are connected to the ground source side water supply pipe, and an electric regulating valve (V11) is provided between the supply and return pipes of the free cooling ground source circulating water pump (6), electric shut-off valves are provided on the pipes of the air source heat pump unit (2) connected to the user side floor heating supply and return pipes and the pipes connected to the user side air conditioning supply and return pipes, electric shut-off valves are provided on the user side floor heating supply and return pipes and the user side air conditioning supply and return pipes, and electric shut-off valves are provided on the supply and return pipes of the free cooling ground source circulating water pump (6); A heat meter is installed on the return water pipe on the ground source side; by measuring the heat intake and heat release of the ground source well in winter and summer, the heat intake and heat release of the ground source well in winter and summer are balanced by adjusting the operating time of the air source heat pump unit; During summer cooling, when the water temperature T1 on the ground source side is greater than 25°C, the ground source heat pump unit (1) is used to generate low-temperature water to cool the user-side air-conditioning unit, and the air source heat pump unit (2) is used to cool the user-side floor heating system.

2. The composite air-conditioning system based on shallow geothermal utilization according to claim 1 is characterized by: Temperature sensors are installed on the user-side floor heating supply and return pipes and the user-side air conditioning supply and return pipes. Temperature sensors are also installed on the ground source side water supply pipes. Each temperature sensor is electrically connected to the control cabinet.

3. The composite air-conditioning system based on shallow geothermal utilization according to claim 2 is characterized by: The opening of the electric regulating valve (V11) is controlled by the floor heating water temperature.

4. The composite air-conditioning system based on shallow geothermal utilization according to claim 2 is characterized by: A temperature and humidity sensor is installed in the user's room and is electrically connected to the control cabinet.

5. The composite air-conditioning system based on shallow geothermal utilization according to claim 3 is characterized in that: Heat meters are installed on the user-side floor heating water supply pipes and the user-side air conditioning water supply pipes, and temperature sensors are also installed in the ground source wells. Each heat meter and temperature sensor in the ground source well is electrically connected to the control cabinet.

6. The composite air-conditioning system based on shallow geothermal utilization according to claim 1, 2, 3, 4, or 5, characterized in that: The ground source heat pump unit (1) and the air source heat pump unit (2) are both two groups connected in parallel.

7. The composite air-conditioning system based on shallow geothermal utilization according to claim 1, 2, 3, 4, or 5, characterized in that: The ground source side water pump (3), the user side water pump (4), and the air source heat pump circulating water pump (5) are all two units arranged in parallel.

8. The operating method of the composite air-conditioning system based on shallow geothermal utilization according to any one of claims 1 to 7, characterized in that: In summer cooling, there are four operating modes, including: Ground source free cooling mode: the ground source side water pump (3) and the ground source circulating water pump (6) for free cooling are turned on, and water is directly supplied to the user side floor heating water supply pipe through the ground source circulating water pump (6) for free cooling, and the indoor cooling is provided by floor heating radiation, and the floor heating return water is transported to the ground source side water supply pipe through the user side floor heating return water pipe; when the indoor dew point temperature T0 is greater than the ground source side water supply temperature T1, the electric regulating valve (V11) is turned on, and the mixed water volume of hot and cold water is adjusted by controlling the opening of the electric regulating valve (V11), so that the floor heating water supply temperature T3 is greater than the dew point temperature T0; Or the ground source side water pump (3) and the free cooling ground source circulating water pump (6) are turned on, and water is directly supplied to the user side air conditioning water supply pipe through the free cooling ground source circulating water pump (6), and the indoor cooling is provided through the user side air conditioning unit, and the air conditioning return water is transported back to the buried pipe (10) through the user side air conditioning return water pipe; Ground source heat pump unit and air source heat pump unit supplement ground source free cooling mode: when the ground source side water supply temperature T1 is less than 25℃, the ground source heat pump unit (1) and the air source heat pump unit (2) are operated to supplement the ground source free cooling gap, and the ground source heat pump unit is operated first to supplement the cooling. When the ground source heat pump unit (1) cannot meet the supplementary cooling, the air source heat pump unit is started to supplement the cooling; the ground source heat pump unit (1), the ground source side water pump (3), the user side water pump (4), and the free cooling ground source circulating water pump (6) are turned on, and the free cooling ground source circulating water pump (6) directly supplies water to the user side floor heating water supply pipe, and the floor heating radiation is used to cool the room. The floor heating return water is passed through the user. The household side floor heating return water pipe is transported to the ground source side water supply pipe, mixed with the ground source side circulating water and then enters the ground source heat pump unit (1). The cold water produced by the ground source heat pump unit (1) is pressurized and circulated by the user side water pump (4) and enters the indoor air conditioning unit through the user side air conditioning water supply pipe. The air conditioning return water flows back to the ground source heat pump unit (1) through the user side air conditioning return water pipe. When the air source heat pump unit (2) and the ground source heat pump unit (1) are operated in parallel, the air conditioning circulating water is pressurized by the air source heat pump circulating water pump (5) and enters the air source heat pump unit (2). After cooling, it enters the indoor air conditioning unit through the user side air conditioning water supply pipe to cool the room, and then flows back to the air source heat pump unit (2) through the user side air conditioning return water pipe. Ground source heat pump unit air conditioning cooling, air source heat pump unit radiation cooling mode: when the water supply temperature T1 on the ground source side is greater than 25°C, the ground source heat pump unit (1) is used to produce low-temperature water to cool the user-side air conditioning unit, and the air source heat pump unit (2) is used to cool the user-side floor heating system; Independent operation mode of ground source heat pump unit and air source heat pump unit: the ground source heat pump unit (1) and the air source heat pump unit (2) operate independently. When the heat intake and heat release of the ground source well are unbalanced in winter and summer, the operation time of the ground source heat pump unit (1) is adjusted by adjusting the operation time of the air source heat pump unit (2), thereby balancing the heat intake and heat release on the ground source side.

9. The working method according to claim 8, characterized in that: When the ground source heat pump unit and the air source heat pump unit are operated independently, the cooling load of the air source heat pump unit is 30% of the total cooling load.

10. The working method according to claim 8, characterized in that: During winter heating, the circulating water in the indoor floor heating pipes is transported by the floor heating return pipe on the user side, enters the ground source heat pump unit (1) and the air source heat pump unit (2) respectively for heating, and is then transported to the indoor floor heating pipes through the floor heating water supply pipes.

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