Geothermal water cascade warming system driven by solar energy

Abstract

The invention discloses a geothermal water cascade warming system driven by solar energy. The geothermal water cascade warming system comprises a well outlet pump, a flat plate collector heat exchange water tank, a flat plate collector square matrix, a circulating pump, a vacuum tube collector heat exchange water tank, a vacuum tube collector square matrix, a CPC collector heat exchange water tank, a CPC collector square matrix, a PTC collector heat exchange water tank, a PTC collector square matrix and a recharge pump. Each heat exchange water tank is connected with the corresponding heat collector square matrix through a circulating pump, and the previous heat exchange water tank can be communicated with the input end of the recharge pump and each downstream heat exchange water tank; and when the temperature of the geothermal water is smaller than the target temperature, the downstream heat collector square matrix with the highest heat collection efficiency is selected to heat the geothermal water, if the temperature of the heated geothermal water is smaller than the target temperature, the downstream heat collector square matrix with the highest heat collection efficiency is continuously selected to heat the geothermal water, and the steps are repeated till the target temperature is reached or heat exchange is completed in the PTC heat collector heat exchange water tank. Through the cooperative heat collection effect between the heat collector square matrixes, the system can keep high heat collection efficiency within the full temperature range.

Description

Technical Field

[0001] The present invention belongs to the technical field of geothermal water development and utilization, and in particular is a geothermal water cascade temperature increasing system driven by solar energy. Background Art

[0002] Geothermal energy, a renewable energy source, offers advantages such as large storage capacity, stable heat source, and clean, pollution-free operation. Currently, geothermal energy is primarily used for power generation, heating, and domestic hot water. However, over time, its thermal quality gradually degrades, and solar energy can be used to supplement warming.

[0003] The thermal utilization of geothermal energy can be divided into three stages according to the temperature range: below 100°C is low-temperature thermal utilization, mainly for heating and providing domestic hot water; 100-250°C is medium-temperature thermal utilization, mainly for providing heat for industrial and agricultural use and low-temperature power generation; and above 250°C is high-temperature thermal utilization, mainly for providing heat for high-temperature power generation. Corresponding to different thermal utilization purposes, solar collectors are divided into three types: low-temperature collectors, medium-temperature collectors, and high-temperature collectors. The thermal collection efficiency of different types of collectors is affected by the inlet water temperature, solar radiation intensity, and ambient temperature. Therefore, the thermal efficiency of the collectors varies in different temperature ranges. When using medium and high temperature heat, if all medium and high temperature collectors are used for auxiliary warming, on the one hand, the thermal collection efficiency of medium and high temperature collectors in the low temperature range is not ideal, and on the other hand, the initial investment and operating costs of the system are also high.

[0004] Therefore, the present invention proposes a solar-driven geothermal water cascade heating system, which combines three types of collectors: low, medium and high. The collector with the highest heat collection efficiency is selected for heat collection and heating within different heating ranges, so that the heating process maintains a high efficiency in the entire temperature range. At the same time, it can reduce the initial investment and operating costs of the system and has good economic benefits. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a solar-driven geothermal water cascade heating system and an operating mode.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] A solar-powered geothermal water cascade heating system comprises a well pump, a flat plate collector heat exchange tank, a flat plate collector array, a circulation pump, a vacuum tube collector heat exchange tank, a vacuum tube collector array, a CPC collector heat exchange tank, a CPC collector array, a PTC collector heat exchange tank, a PTC collector array, and a recharge pump;

[0008] The output end of the out-well pump can be connected to the low-temperature side inlet end of the flat-plate collector water exchange tank, the vacuum tube collector water exchange tank, the CPC collector water exchange tank and the PTC collector water exchange tank; the flat-plate collector water exchange tank is connected to the flat-plate collector array via a circulation pump, and the high-temperature side outlet end of the flat-plate collector water exchange tank can be connected to the input end of the recharge pump and the low-temperature side inlet end of the vacuum tube collector water exchange tank, the CPC collector water exchange tank and the PTC collector water exchange tank; the vacuum tube collector water exchange tank is connected to the vacuum tube collector array via a circulation pump, and the vacuum tube The high-temperature side outlet end of the collector water exchange tank can be connected to the input end of the recharge pump and the low-temperature side inlet ends of the CPC collector water exchange tank and the PTC collector water exchange tank; the CPC collector water exchange tank is connected to the CPC collector array via a circulation pump, and the high-temperature side outlet end of the CPC collector water exchange tank can be connected to the input end of the recharge pump and the low-temperature side inlet end of the PTC collector water exchange tank; the PTC collector water exchange tank is connected to the PTC collector array via a circulation pump, and the high-temperature side outlet end of the PTC collector water exchange tank is connected to the input end of the recharge pump.

[0009] Furthermore, if the geothermal water temperature at the outlet of the water well is lower than the target temperature, the heat collection efficiency of each collector array is calculated, and the collector array with the highest heat collection efficiency is selected to perform the first stage of warming the geothermal water; if the flat-plate collector array has the highest heat collection efficiency, the geothermal water enters the flat-plate collector water exchange tank for heat exchange; if the vacuum tube collector array has the highest heat collection efficiency, the geothermal water enters the vacuum tube collector water exchange tank for heat exchange; if the CPC collector array has the highest heat collection efficiency, the geothermal water enters the CPC collector water exchange tank for heat exchange; if the PTC collector array has the highest heat collection efficiency, the geothermal water enters the PTC collector water exchange tank for heat exchange; the geothermal water temperature after the first stage of warming is measured, and if it is lower than the target temperature, the heat collection efficiency of each downstream collector array is calculated, and the collector array with the highest heat collection efficiency is selected to perform the second stage of warming the geothermal water; this cycle is repeated until the geothermal water reaches the target temperature or the heat exchange is completed in the PTC collector water exchange tank.

[0010] Furthermore, the heat collection efficiency of the collector array is calculated by the following formula:

[0011] η=η0-α0T i * (1)

[0012]

[0013] Where: η represents the heat collection efficiency of the collector array, T i * is the normalized temperature difference, η0 represents the heat collection efficiency when the normalized temperature difference is 0, α0 represents the heat loss coefficient of the collector array, T i Indicates the inlet temperature of the collector array, Ta represents the ambient temperature, and I represents the solar radiation intensity.

[0014] Furthermore, the system also includes a temperature sensor; the output end of the well pump, the high-temperature side outlet end of the flat-plate collector water exchange tank, the high-temperature side outlet end of the vacuum tube collector water exchange tank, the high-temperature side outlet end of the CPC collector water exchange tank, and the high-temperature side outlet end of the PTC collector water exchange tank are all provided with temperature sensors.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1) This application deploys different types of collector arrays for low, medium and high temperatures. Different collectors have different heat collection advantages at different operating temperatures. Therefore, the collector array with the highest heat collection efficiency is selected in different temperature increase ranges to perform step-by-step temperature increase on the geothermal water, so that the temperature increase process maintains a high heat collection efficiency in the entire temperature range; different types of collector arrays produce a synergistic heat collection effect, solving the problems of insufficient heating in winter due to insufficient solar radiation intensity, low heat collection efficiency caused by mismatch of water temperature, and excessive initial investment and operating costs of the system due to improved geothermal water quality in the prior art. In addition, different types of collectors can be selected and combined according to specific application scenarios. For example, a flat-plate collector performs well at lower inlet water temperatures, but its efficiency will gradually decrease as the inlet water temperature increases; while a vacuum tube collector can still maintain a high heat collection efficiency at higher inlet water temperatures. This flexibility enables the system to be optimized according to actual needs to achieve optimal performance.

[0017] 2) This application has designed a matching heat exchange tank for each collector array. On the one hand, this allows for heat exchange between geothermal water and the collector array. On the other hand, the collected heat can be temporarily stored in the heat exchange tank. Once the geothermal water temperature rises to the required level, it can be heated or recharged to the next level. This design allows the system to adjust according to actual heat demand and achieve efficient heat utilization. The design of the heat exchange tank further improves the flexibility and stability of the system, enabling the system to rationally manage heat storage and release. This not only helps balance the supply and demand of heat in the system, but also improves the system's adaptability to sudden environmental changes, ensuring more reliable system operation.

[0018] 3) This application uses a lower-cost collector in the low-temperature section to replace the collector with more complex manufacturing technology and relatively higher manufacturing and operating costs. This design not only initially improves the quality of geothermal water, but also further reduces the overall cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the overall structural diagram of the present invention;

[0020] Figure 2 Comparison of collector array efficiency under different normalized temperature differences;

[0021] Figure 3 It is a graph of solar radiation intensity and ambient temperature changes on a typical day;

[0022] Figure 4 This is a comparison chart of the heat collection efficiency and total heat collection efficiency of different collector arrays when connected in series;

[0023] Figure 5 This is a schematic diagram of the outlet temperature and recharging temperature of different water exchange tanks when connected in series;

[0024] In the figure, 1-outlet pump; 2-cyclone desander; 3-flat plate collector heat exchange tank; 4-flat plate collector array; 5-first stage circulation pump; 6-vacuum tube collector heat exchange tank; 7-vacuum tube collector array; 8-second stage circulation pump; 9-CPC (compound parabolic) collector heat exchange tank; 10-CPC collector array; 11-third stage circulation pump; 12-PTC (parabolic trough) collector heat exchange tank; 13-PTC collector array; 14-fourth stage circulation pump; 15-recharge pump; 16-outlet well; 17-recharge well; 18-first branch pipe; 19-second branch pipe; 20-third branch pipe; 21-fourth branch pipe; 22-PLC controller. DETAILED DESCRIPTION

[0025] Specific embodiments are given below in conjunction with the accompanying drawings. The specific embodiments are only used to introduce the technical solutions of the present invention in detail and are not intended to limit the scope of protection of the present application.

[0026] The present invention provides a solar-driven geothermal water cascade warming system, comprising a well pump 1, a cyclone desander 2, a flat-plate collector water exchange tank 3, a flat-plate collector array 4, a first-stage circulation pump 5, a vacuum tube collector water exchange tank 6, a vacuum tube collector array 7, a second-stage circulation pump 8, a CPC collector water exchange tank 9, a CPC collector array 10, a third-stage circulation pump 11, a PTC collector water exchange tank 12, a PTC collector array 13, a fourth-stage circulation pump 14, a recharge pump 15, a first branch pipe 18, a second branch pipe 19, a third branch pipe 20, a fourth branch pipe 21, and a PLC controller 22;

[0027] The outlet pump 1 is located in the outlet well 16. The output end of the outlet pump 1 is connected to the inlet end of the cyclone desander 2 through a hot water pipeline. The outlet end of the cyclone desander 2 is connected to the low-temperature side inlet end of the flat-plate heat collector water exchange tank 3 via a No. 1 three-way valve DV1. The low-temperature side outlet end of the flat-plate heat collector water exchange tank 3 is connected to the inlet end of the flat-plate heat collector array 4 via a first-stage circulation pump 5. The outlet end of the flat-plate heat collector array 4 is connected to the high-temperature side inlet end of the flat-plate heat collector water exchange tank 3. The high-temperature side outlet end of the flat-plate heat collector water exchange tank 3 is connected to the inlet end of the first branch pipe 18 via a No. 2 three-way valve DV2. The inlet end of the first branch pipe 18 is also connected to the No. 1 three-way valve DV1.

[0028] The low-temperature side inlet end of the vacuum tube heat collector water exchange tank 6 is connected to the outlet end of the first branch pipe 18 via the No. 3 three-way valve DV3. The low-temperature side outlet end of the vacuum tube heat collector water exchange tank 6 is connected to the inlet end of the vacuum tube heat collector array 7 via the second-stage circulation pump 8. The outlet end of the vacuum tube heat collector array 7 is connected to the high-temperature side inlet end of the vacuum tube heat collector water exchange tank 6. The high-temperature side outlet end of the vacuum tube heat collector water exchange tank 6 is connected to the inlet end of the second branch pipe 19 via the No. 4 three-way valve DV4. The inlet end of the second branch pipe 19 is also connected to the No. 3 three-way valve DV3.

[0029] The low-temperature side inlet end of the CPC heat collector water exchange tank 9 is connected to the outlet end of the second branch pipe 19 via the No. 5 three-way valve DV5. The low-temperature side outlet end of the CPC heat collector water exchange tank 9 is connected to the inlet end of the CPC heat collector array 10 via the third-stage circulation pump 11. The outlet end of the CPC heat collector array 10 is connected to the high-temperature side inlet end of the CPC heat collector water exchange tank 9. The high-temperature side outlet end of the CPC heat collector water exchange tank 9 is connected to the inlet end of the third branch pipe 20 via the No. 6 three-way valve DV6. The inlet end of the third branch pipe 20 is also connected to the No. 5 three-way valve DV5.

[0030] The low-temperature side inlet end of the PTC heat collector water exchange tank 12 is connected to the outlet end of the third branch pipe 20 via the No. 7 three-way valve DV7. The low-temperature side outlet end of the PTC heat collector water exchange tank 12 is connected to the inlet end of the PTC heat collector array 13 via the fourth-stage circulation pump 14. The outlet end of the PTC heat collector array 13 is connected to the high-temperature side inlet end of the PTC heat collector water exchange tank 12. The high-temperature side outlet end of the PTC heat collector water exchange tank 12 is connected to the inlet end of the fourth branch pipe 21 via the No. 8 three-way valve DV8. The inlet end of the fourth branch pipe 21 is also connected to the No. 7 three-way valve DV7. The outlet end of the fourth branch pipe 21 is connected to the recharge well 17 via the recharge pump 15.

[0031] A temperature sensing probe No. 1 T1 is provided at the outlet end of the cyclone desander 2 for measuring the outlet temperature of geothermal water; a temperature sensing probe No. 2 T2 is provided at the high-temperature side outlet end of the flat-plate collector water exchange tank 3, a temperature sensing probe No. 3 T3 is provided at the high-temperature side outlet end of the vacuum tube collector water exchange tank 6, a temperature sensing probe No. 4 T4 is provided at the high-temperature side outlet end of the CPC collector water exchange tank 9, and a temperature sensing probe No. 5 T5 is provided at the high-temperature side outlet end of the PTC collector water exchange tank 12, which are respectively used to measure the temperature of geothermal water after heat exchange in the corresponding water exchange tanks; all temperature sensing probes and three-way valves are connected to the PLC controller 22.

[0032] The specific operating modes are as follows:

[0033] The heat collection efficiency of the collector array is affected by the inlet temperature, ambient temperature and solar radiation intensity. The heat collection efficiency of the collector array can be calculated according to the following empirical formula:

[0034] η=η0-α0T i * (1)

[0035]

[0036] Where: η represents the heat collection efficiency of the collector array; T i * is the normalized temperature difference, K·m 2 / W; η0 represents the heat collection efficiency when the normalized temperature difference is 0; α0 represents the heat loss coefficient of the collector array, W / (m 2 ·K); T i represents the inlet temperature of the collector array, ℃; T a represents the ambient temperature, ℃; I represents the solar radiation intensity, W / m 2 .

[0037] First, the geothermal water passes through the well pump 1 and the cyclone desander 2, and the geothermal water temperature is measured by the No. 1 temperature sensor T1. If the geothermal water temperature is lower than the target temperature, the heat collection efficiency of each collector array is calculated, and the collector array with the highest heat collection efficiency is selected to heat the geothermal water. If the heat collection efficiency of the flat plate collector array 4 is the highest at this time, the PLC controller 22 controls the No. 1 three-way valve DV1 to allow the geothermal water to preferentially enter the flat plate collector heat exchange tank 3 and exchange heat with the flat plate collector array 4; if the heat collection efficiency of the vacuum tube collector array 7 is the highest at this time, the PLC controller 22 controls the No. 1 three-way valve DV1 to the No. 3 three-way valve DV3 to allow the geothermal water to preferentially enter the vacuum tube collector heat exchange tank 6 and exchange heat with the vacuum tube collector array 7. The empty tube collector array 7 exchanges heat; if the CPC collector array 10 has the highest heat collection efficiency at this time, the PLC controller 22 controls the No. 1 three-way valve DV1 to the No. 5 three-way valve DV5, so that the geothermal water passes through the first branch pipe 18 and the second branch pipe 19 and preferentially enters the CPC collector water exchange tank 9 for heat exchange with the CPC collector array 10; if the PTC collector array 13 has the highest heat collection efficiency at this time, the PLC controller 22 controls the No. 1 three-way valve DV1 to the No. 7 three-way valve DV7, so that the geothermal water passes through the first branch pipe 18, the second branch pipe 19 and the third branch pipe 20 and preferentially enters the PTC collector water exchange tank 12 for heat exchange with the PTC collector array 13; at this point, the first stage of geothermal water temperature increase is completed;

[0038] Then, the temperature of the geothermal water after heat exchange is measured using the temperature sensor at the outlet end of the high-temperature side of the corresponding heat exchange water tank. If the temperature of the geothermal water after heat exchange is lower than the target temperature, the above process is repeated to calculate the heat collection efficiency of each downstream collector array, and the collector array with the highest heat collection efficiency is selected to perform the second-stage temperature increase on the geothermal water. This cycle is repeated until the geothermal water reaches the target temperature or completes the heat exchange with the PTC collector heat exchange water tank 12. The geothermal water that has completed the heat exchange is returned to the recharge well 17 through the recharge pump 15 for use in heating and power generation.

[0039] Example

[0040] After the geothermal water passes through the well pump 1 and the cyclone desander 2, the geothermal water temperature is measured using the No. 1 temperature sensor T1. If the temperature of the No. 1 temperature sensor T1 is lower than the target temperature T, the normalized temperature difference is calculated based on the inlet temperature of the collector array, the ambient temperature, and the solar radiation intensity. The heat collection efficiency of each collector array is then calculated based on the normalized temperature difference, and the collector array with the highest heat collection efficiency is selected for heat exchange.

[0041] If the heat collection efficiency of the flat-plate collector array 4 is the highest, the normalized temperature difference is less than or equal to 0.05K·m 2 / W, the first three-way valve DV1 is opened to allow the geothermal water to enter the flat plate collector heat exchange tank 3 and exchange heat with the flat plate collector array 4. The geothermal water after heat exchange flows through the second three-way valve DV2 and then flows through the first branch pipe 18. The second temperature sensor T2 measures the geothermal water temperature. If the temperature of the second temperature sensor T2 is lower than the target temperature T, the geothermal water continues to exchange heat with the downstream collector array with the highest heat collection efficiency. In this way, the geothermal water temperature is gradually increased step by step until the geothermal water temperature is greater than or equal to the target temperature. The geothermal water that has been heated is then returned to the heat exchanger. The water is pumped back to the recharge well 17 through the recharge pump 15. If the temperature of the second temperature sensor T2 is greater than or equal to the target temperature T, the third three-way valve DV3 to the eighth three-way valve DV8 are controlled to allow the geothermal water to flow through the second branch pipe 19 to the fourth branch pipe 21 and the recharge pump 15 and return to the recharge well 17. The circulation pumps corresponding to the collector arrays in the vacuum tube collector array 7, the CPC collector array 10, and the PTC collector array 13 that are not exchanging heat with the geothermal water are turned on, so that the collector arrays exchange heat with the corresponding heat exchange water tanks and store the heat in the heat exchange water tanks.

[0042] If the heat collection efficiency of the vacuum tube collector array 7 is the highest, the normalized temperature difference is greater than 0.05 and less than or equal to 0.12 K·m 2 / W, open the No. 1 three-way valve DV1 to the No. 3 three-way valve DV3, so that the geothermal water flows through the first branch pipe 18, enters the vacuum tube collector water exchange tank 6 and exchanges heat with the vacuum tube collector array 7. After heat exchange, the geothermal water flows through the No. 4 three-way valve DV4 and the second branch pipe 19. The No. 3 temperature sensor T3 measures the geothermal water temperature. If the temperature of the No. 3 temperature sensor T3 is lower than the target temperature, the geothermal water continues to exchange heat with the downstream collector array with the highest heat collection efficiency. In this way, the geothermal water temperature is gradually increased step by step until the geothermal water temperature is greater than or equal to the target temperature T. The heated geothermal water is returned to the recharge well 17 via the recharge pump 15. If the temperature of the third temperature sensor T3 is greater than or equal to the target temperature T, the fifth three-way valve DV5 to the eighth three-way valve DV8 are controlled to allow the geothermal water to flow through the second branch pipe 19 to the fourth branch pipe 21 and the recharge pump 15 and return to the recharge well 17. The circulation pumps corresponding to the collector arrays in the flat plate collector array 4, the CPC collector array 10, and the PTC collector array 13 that are not exchanging heat with the geothermal water are turned on, so that the collector arrays exchange heat with the corresponding heat exchange water tanks and store the heat in the heat exchange water tanks.

[0043] If the CPC collector array 10 has the highest heat collection efficiency, the normalized temperature difference is greater than 0.12 and less than or equal to 0.15 K·m 2 / W, open the No. 1 three-way valve DV1 to the No. 5 three-way valve DV5, so that the geothermal water flows through the first branch pipe 18 and the second branch pipe 19, enters the CPC collector water exchange tank 9 and exchanges heat with the CPC collector array 10. The geothermal water after heat exchange flows through the No. 6 three-way valve DV6 and the third branch pipe 20. The No. 4 temperature sensor T4 measures the geothermal water temperature. If the temperature of the No. 4 temperature sensor T4 is lower than the target temperature T, the geothermal water continues to exchange heat with the PTC collector array 13, so that the geothermal water temperature is greater than or equal to the target temperature T, and the heating is completed. The geothermal water flows back to the recharge well 17 via the recharge pump 15. If the temperature of the fourth temperature sensor T4 is greater than or equal to the target temperature T, the seventh three-way valve DV7 and the eighth three-way valve DV8 are controlled to allow the geothermal water to flow back to the recharge well 17 via the third branch pipe 20, the fourth branch pipe 21, and the recharge pump 15. The circulation pumps corresponding to the collector arrays in the flat plate collector array 4, the vacuum tube collector array 7, and the PTC collector array 13 that are not exchanging heat with the geothermal water are turned on, allowing the collector arrays to exchange heat with the corresponding heat exchange tanks, storing the heat in the heat exchange tanks.

[0044] If the heat collection efficiency of the PTC collector array 13 is the highest, the normalized temperature difference is greater than or equal to 0.15K·m 2 / W, open the No. 1 three-way gate valve DV1 to the No. 7 three-way valve DV7, so that the geothermal water flows through the first branch pipe 18, the second branch pipe 19 and the third branch pipe 20, and enters the PTC collector water exchange tank 12 to exchange heat with the PTC collector array 13. The geothermal water after heat exchange passes through the No. 8 three-way valve DV8 and the fourth branch pipe 21, and the No. 5 temperature sensor T5 measures the geothermal water temperature. The heated geothermal water is returned to the recharge well 17 through the recharge pump 15; the circulation pumps corresponding to the collector arrays that are not exchanging heat with the geothermal water in the flat plate collector array 4, the vacuum tube collector array 7 and the CPC collector array 10 are opened, so that the collector arrays exchange heat with the corresponding water exchange tanks and store the heat in the water exchange tanks.

[0045] In order to illustrate the cascade warming performance of this system, the summer solstice in a certain area is taken as a typical day. The minimum ambient temperature on that day is 3.7℃, the maximum ambient temperature is 19.0℃, and the peak solar radiation intensity is 1018.6W / m 2 The solar radiation intensity and ambient temperature variation curves for this typical day can be found in Figure 3 .

[0046] Figure 4 This is a comparison of the heat collection efficiency and total heat collection efficiency of different collector arrays when the flat plate collector array 4, the vacuum tube collector array 7, the CPC collector array 10 and the PTC collector array 13 are connected in series in sequence. Figure 5This is a comparison of the outlet temperature and recharge temperature of different heat exchange tanks when the flat plate collector array 4, the vacuum tube collector array 7, the CPC collector array 10 and the PTC collector array 13 are connected in series in sequence. The initial temperature of the geothermal water is set to 20°C. At 8:00 am, the geothermal water temperature is measured by the No. 1 temperature sensor T1. The PLC controller 22 determines that the current heat collection efficiency of the flat plate collector array 4 is the highest, which is 30.2%. The geothermal water is then heated by the flat plate collector heat exchange tank 3. The No. 2 temperature sensor T2 detects that the geothermal water temperature after heat exchange with the flat plate collector heat exchange tank 3 is 23.3°C. The PLC controller 22 determines that the current heat collection efficiency of the vacuum tube collector array 7 is the highest, which is 30.3%. The geothermal water is then heated by the vacuum tube collector heat exchange tank 6. The No. 3 temperature sensor T3 detects that the geothermal water temperature after heat exchange with the vacuum tube collector heat exchange tank 6 is 23.3°C. The geothermal water temperature is 31.8℃, and the heat collection efficiency of other collector arrays is insufficient, and no heat exchange is carried out with the geothermal water; at 9:07, the No. 1 temperature sensor T1 measures the geothermal water outlet problem, and the PLC controller 22 determines that the heat collection efficiency of the flat plate collector array 4 is the highest, which is 60.6%. The geothermal water is then heated up by heat exchange with the flat plate collector heat exchange tank 3. The No. 2 temperature sensor T2 detects that the geothermal water temperature after heat exchange with the flat plate collector heat exchange tank 3 is 35.2℃. The PLC controller 22 determines that the current vacuum tube collector array 7 has the highest heat collection efficiency, which is 55.4%. The geothermal water continues to heat up with the vacuum tube collector heat exchange tank 6. The No. 3 temperature sensor Head T3 detects that the geothermal water temperature after heat exchange with the vacuum tube collector heat exchange tank 6 is 61.5℃. The PLC controller 22 determines that the heat collection efficiency of the CPC collector array 10 is the highest, which is 34.4%. Therefore, the CPC collector heat exchange tank 9 is used to exchange heat with the geothermal water. The fourth temperature sensor T4 detects that the geothermal water temperature after heat exchange with the CPC collector heat exchange tank 9 is 90.1℃. The PLC controller 22 determines that the current heat collection efficiency of the PTC collector array 13 is the highest, which is 5.6%. Therefore, the geothermal water continues to exchange heat with the PTC collector heat exchange tank 12 to increase the temperature. The fourth temperature sensor T4 detects that the geothermal water and the PTC collector heat exchange tank 1 are 2 The outlet temperature after heat exchange is 124.1℃; afterwards, the geothermal water is heated in a step-by-step manner in the order of flat-plate collector array 4, vacuum tube collector array 7, CPC collector array 10 and PTC collector array 13, with the highest temperature reaching 268.1℃; until 17:45, the third temperature sensor T3 detects that the geothermal water temperature after heat exchange in vacuum tube collector array 7 is 73.6℃. At this time, neither CPC collector array 10 nor PTC collector array 13 can continue to collect heat and increase temperature, so the collected heat is stored in the corresponding heat exchange tank; at 19:15, the collection efficiency of each collector array drops to zero, and the system stops collecting heat.

[0047] Depend on Figure 4 、 5It can be seen that the system can maintain good heat collection efficiency and high recharge temperature from 8:00 to 19:15. By comparing and selecting the collector array with the highest heat collection efficiency to heat the geothermal water, the collector works in the optimal heat collection efficiency range. In the non-optimal heat collection efficiency range, the collected heat is stored in the heat exchange tank, which improves the overall efficiency and solves the problems in the existing technology of insufficient heating due to insufficient solar radiation intensity, low heat collection efficiency caused by mismatch of hot water temperature, and excessive initial investment and operating costs of the system due to improving the quality of geothermal water.

[0048] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A solar-driven geothermal water cascade heating system, characterized in that: Including outflow pump, flat plate collector heat exchange tank, flat plate collector array, circulation pump, vacuum tube collector heat exchange tank, vacuum tube collector array, CPC collector heat exchange tank, CPC collector array, PTC collector heat exchange tank, PTC collector array and recharge pump; The output end of the out-well pump can be connected to the low-temperature side inlet end of the flat-plate collector water exchange tank, the vacuum tube collector water exchange tank, the CPC collector water exchange tank and the PTC collector water exchange tank; the flat-plate collector water exchange tank is connected to the flat-plate collector array via a circulation pump, and the high-temperature side outlet end of the flat-plate collector water exchange tank can be connected to the input end of the recharge pump and the low-temperature side inlet end of the vacuum tube collector water exchange tank, the CPC collector water exchange tank and the PTC collector water exchange tank; the vacuum tube collector water exchange tank is connected to the vacuum tube collector array via a circulation pump, and the vacuum tube The high-temperature side outlet end of the collector water exchange tank can be connected to the input end of the recharge pump and the low-temperature side inlet ends of the CPC collector water exchange tank and the PTC collector water exchange tank; the CPC collector water exchange tank is connected to the CPC collector array via a circulation pump, and the high-temperature side outlet end of the CPC collector water exchange tank can be connected to the input end of the recharge pump and the low-temperature side inlet end of the PTC collector water exchange tank; the PTC collector water exchange tank is connected to the PTC collector array via a circulation pump, and the high-temperature side outlet end of the PTC collector water exchange tank is connected to the input end of the recharge pump.

2. The solar-powered geothermal water cascade heating system according to claim 1, characterized in that: If the geothermal water temperature at the outlet of the water well is lower than the target temperature, the heat collection efficiency of each collector array is calculated, and the collector array with the highest heat collection efficiency is selected to perform the first stage of warming the geothermal water; if the flat plate collector array has the highest heat collection efficiency, the geothermal water enters the flat plate collector water exchange tank for heat exchange; if the vacuum tube collector array has the highest heat collection efficiency, the geothermal water enters the vacuum tube collector water exchange tank for heat exchange; if the CPC collector array has the highest heat collection efficiency, the geothermal water enters the CPC collector water exchange tank for heat exchange; if the PTC collector array has the highest heat collection efficiency, the geothermal water enters the PTC collector water exchange tank for heat exchange; the geothermal water temperature after the first stage of warming is measured, and if it is lower than the target temperature, the heat collection efficiency of each downstream collector array is calculated, and the collector array with the highest heat collection efficiency is selected to perform the second stage of warming the geothermal water; this cycle is repeated until the geothermal water reaches the target temperature or the heat exchange is completed in the PTC collector water exchange tank.

3. The solar-powered geothermal water cascade heating system according to claim 2, characterized in that: The heat collection efficiency of the collector array is calculated by the following formula: η=η0-α0T i * (1) Where: η represents the heat collection efficiency of the collector array, T i * is the normalized temperature difference, η0 represents the heat collection efficiency when the normalized temperature difference is 0, α0 represents the heat loss coefficient of the collector array, T i Indicates the inlet temperature of the collector array, T a represents the ambient temperature, and I represents the solar radiation intensity.

4. The solar-powered geothermal water cascade heating system according to any one of claims 1 to 3, characterized in that: The system also includes a temperature sensor; the output end of the well pump, the high-temperature side outlet end of the flat-plate collector water exchange tank, the high-temperature side outlet end of the vacuum tube collector water exchange tank, the high-temperature side outlet end of the CPC collector water exchange tank, and the high-temperature side outlet end of the PTC collector water exchange tank are all provided with a temperature sensor.

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