A compound buried pipe ground source heat pump system and its optimization method

Abstract

The present invention discloses a composite buried pipe ground-source heat pump system and an optimization method thereof. The optimization method comprises obtaining a building's cooling and heating loads; determining whether the building's cooling and heating loads are dominant or non-dominant; defining a dominant load ratio and a non-dominant load ratio; iteratively solving the dominant load ratio, the non-dominant load ratio, and the length of the vertical buried pipe based on a pre-constructed vertical buried pipe length design equation; calculating the trench length of the horizontal spiral buried pipe based on the solved dominant load ratio and the non-dominant load ratio based on a pre-constructed trench design equation for the horizontal spiral buried pipe; obtaining a levelized cost of energy based on the vertical buried pipe length and the trench length of the horizontal spiral buried pipe; and obtaining the final vertical buried pipe length and trench length of the horizontal spiral buried pipe with the goal of minimizing the levelized cost of energy. The present invention can ensure the long-term and efficient operation of the composite buried pipe ground-source heat pump system at a low cost.

Description

Technical Field

[0001] The present invention relates to a composite buried pipe ground source heat pump system and an optimization method thereof, belonging to the technical field of ground source heat pumps. Background Art

[0002] A geothermal heat pump system is a highly efficient and energy-saving device that utilizes shallow underground geothermal resources (including groundwater, underground rock and soil, or surface water) to provide both heating and cooling. Buried-pipe geothermal heat pump systems are increasingly gaining popularity due to their limited environmental constraints. They utilize the relatively stable underground soil temperature and, with a small input of high-potential energy, exchange heat with the earth through buried heat exchangers, achieving summer cooling and winter heating. They can also provide domestic hot water. During year-round operation, the heat pump absorbs heat from the ground in winter to heat the building, while simultaneously lowering the temperature around the buried heat exchanger. In summer, the heat pump transfers heat from the building to the ground, cooling the building and raising the temperature around the buried heat exchanger.

[0003] A buried pipe geothermal heat pump system typically consists of a buried pipe heat exchanger, a heat pump unit, and a terminal unit. As a core component of a buried pipe geothermal heat pump system, the buried pipe heat exchanger significantly impacts its thermal performance. Currently, buried pipe geothermal heat pump systems are often designed using empirical rules or traversal algorithms. However, empirical rules lack design accuracy, while traversal algorithms suffer from low computational efficiency, failing to guarantee system cost and thermal performance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art, provide a composite buried pipe ground source heat pump system and its optimization method, and solve the technical problem that the prior art cannot effectively control the cost and thermal performance of the buried pipe ground source heat pump system.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides an optimization method for a composite buried pipe ground-source heat pump system, wherein the composite buried pipe ground-source heat pump system includes a vertical buried pipe heat pump system and a horizontal spiral buried pipe heat pump system. The optimization method includes:

[0007] Obtaining the cooling and heating loads of the building, and obtaining the peak cooling and heating loads of the building and the cumulative cooling and heating loads of the building based on the cooling and heating loads of the building;

[0008] Determine whether the building's cooling and heating load is a dominant load or a non-dominant load based on the building's cumulative cooling and heating load;

[0009] The dominant load ratio and non-dominant load ratio are defined based on the ratio of the maximum cooling and heating load borne by the vertical buried pipe heat pump system to the peak cooling and heating load of the building;

[0010] Based on the pre-built vertical buried pipe length design equation, the defined dominant load ratio, non-dominant load ratio and the corresponding vertical buried pipe length required for the vertical buried pipe heat pump system are iteratively solved;

[0011] Based on the pre-built trench design equation for horizontal spiral underground pipes, the trench length required for the horizontal spiral underground pipe heat pump system is calculated according to the solved dominant load ratio and non-dominant load ratio;

[0012] The investment cost, operation cost, maintenance cost and heat transfer are obtained based on the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe under the solved dominant load ratio and non-dominant load ratio;

[0013] Calculate the levelized cost of energy based on investment cost, operating cost, maintenance cost and heat transfer;

[0014] With the goal of minimizing the levelized cost of energy, the final length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe are obtained.

[0015] Optionally, determining whether the building's cooling and heating load is a dominant load or a non-dominant load based on the building's cumulative cooling and heating loads includes:

[0016] If the cumulative cooling load is greater than the cumulative heating load, the building cooling load is the dominant load and the building heating load is the non-dominant load; if the cumulative cooling load is less than or equal to the cumulative heating load, the building heating load is the dominant load and the building cooling load is the non-dominant load.

[0017] Optionally, the dominant load ratio α, α∈[0,1] is the ratio of the maximum dominant load borne by the vertical buried pipe heat pump system to the peak dominant load of the building; the non-dominant load ratio β, β∈[0,1] is the ratio of the maximum non-dominant load borne by the vertical buried pipe heat pump system to the peak non-dominant load of the building.

[0018] Optionally, the iteratively solving the defined dominant load ratio, the non-dominant load ratio, and the corresponding vertical buried pipe length required for the vertical buried pipe heat pump system includes:

[0019] Step S1, initializing the dominant load ratio α=0, and the non-dominant load ratio β=1;

[0020] Step S2: Obtain the maximum cooling and heating load of the vertical buried pipe heat pump system according to the product of the dominant load ratio α, the non-dominant load ratio β and the peak cooling and heating load of the building;

[0021] Step S3: Calculate the required vertical buried pipe lengths for the vertical buried pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-established vertical buried pipe length design equations;

[0022] Step S4: taking the larger value of the vertical buried pipe lengths required for the vertical buried pipe heat pump system in cooling and heating conditions as the required vertical buried pipe length for the vertical buried pipe heat pump system;

[0023] Step S5: Calculate the difference based on the lengths of the vertical buried pipes required for cooling and heating conditions, and determine whether the relative difference is greater than a preset difference value. If so, reduce the non-dominant load ratio β by a preset decreasing step size, and bring the above step S2 into iteration;

[0024] Step S6: If not, output the current dominant load ratio α and non-dominant load ratio β, increase the dominant load ratio α by a preset incremental step, and return to the above step S2 for iteration.

[0025] Optionally, obtaining the maximum cooling and heating loads of the vertical buried pipe heat pump system further includes:

[0026] Determine whether the maximum cooling and heating load of the vertical buried pipe heat pump system is greater than or equal to the cooling and heating load of the building;

[0027] If so, the vertical buried pipe heat pump system bears the cooling and heating loads of the building; if not, the vertical buried pipe heat pump system and the horizontal buried pipe heat pump system jointly bear the cooling and heating loads of the building, and the horizontal buried pipe heat pump system bears the part of the maximum cooling and heating load of the vertical buried pipe heat pump system that is less than the cooling and heating load of the building.

[0028] Optionally, the pre-built vertical buried pipe length design equation is:

[0029]

[0030] Among them, L cooling .BHE and L heating .BHE are the lengths of vertical buried pipes required for the vertical buried pipe heat pump system in cooling and heating conditions, respectively, and q net is the net geothermal energy injected / extracted by vertical buried pipes throughout the year, R sa 、R sm 、R sst are the soil thermal resistance under continuous pulse load at preset time, month and year cycles, R b is the drilling thermal resistance, PLF m is the operating share of cooling and heating conditions in the corresponding month, F sc Thermal short-circuit loss factor caused by thermal interaction between the inlet and outlet pipes, T0 is the initial soil temperature, ELT and LLT are the rated inlet and outlet water temperatures of the heat pump unit, respectively, Tp is the soil penalty temperature caused by all thermal interactions between water pipes, q cond and q evap They are the maximum cooling and heating loads of the vertical buried pipe heat pump system corresponding to cooling and heating conditions respectively.

[0031] Optionally, the calculation of the trench length of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system includes:

[0032] The maximum cooling and heating loads of the horizontal spiral buried pipe heat pump system are obtained by multiplying the solved dominant load ratio α, non-dominant load ratio β and the building's peak cooling and heating loads.

[0033] Calculate the required trench length for the horizontal spiral underground pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-built trench design equation for the horizontal spiral underground pipe.

[0034] The trench design equation for the pre-built horizontal spiral buried pipe is:

[0035]

[0036] Among them, L cooling .HGHE and L heating HGHE are the trench lengths of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system in cooling and heating conditions, respectively. net is the net geothermal energy injected / extracted by the horizontal spiral buried pipe throughout the year, R sa 、R sm 、R sst are the soil thermal resistance under continuous pulse load at preset time, month and year cycles, R p is the buried pipe thermal resistance, PLF m is the operating share of cooling and heating conditions in the corresponding month, F sc The thermal short-circuit loss factor caused by the thermal interaction between the inlet and outlet water pipes, ELT and LLT are the rated inlet and outlet water temperatures of the heat pump unit, T p is the soil penalty temperature caused by all thermal interactions between water pipes, T H,cooling and T H,heating are the maximum temperature value of the soil depth at the center axis of the horizontal spiral buried pipe in the cooling condition and the minimum temperature value of the heating condition, respectively. cond and q evap are the maximum cooling and heating loads of the horizontal spiral underground pipe heat pump system corresponding to cooling and heating conditions respectively;

[0037] The larger value of the trench length of the horizontal spiral buried pipe required for the horizontal spiral buried pipe heat pump system under cooling and heating conditions is taken as the trench length of the horizontal spiral buried pipe.

[0038] Optionally, the investment cost, operating cost and maintenance cost are obtained based on preset calculation rules according to the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe; the heat transfer amount is obtained based on pre-built simulation software according to the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe.

[0039] Optionally, the levelized cost of energy is:

[0040]

[0041] Among them, LCoE is the levelized cost of energy, IC is the investment cost, OC is the y is the operating cost in year y, MC y is the maintenance cost in year y, Q y is the heat transferred in year y, IR is the interest rate, and Y is the total number of years.

[0042] In the second aspect, the present invention provides a composite buried pipe ground source heat pump system, including a vertical buried pipe heat pump system and a horizontal spiral buried pipe heat pump system, the vertical buried pipe heat pump system includes a vertical buried pipe heat pump unit, the ground source side of the vertical buried pipe heat pump unit is connected in series with a vertical buried pipe group, a first ground source side water pump and a first ground source side valve, and the vertical buried pipe group includes multiple parallel vertical buried pipes; the horizontal spiral buried pipe heat pump system includes a horizontal spiral buried pipe heat pump unit, the ground source side of the horizontal spiral buried pipe heat pump unit is connected in series with a horizontal spiral buried pipe group, a second ground source side water pump and a second ground source side valve, and the horizontal spiral buried pipe group includes multiple parallel horizontal spiral buried pipes; the composite buried pipe ground source heat pump system adopts an optimization method for a composite buried pipe ground source heat pump system as described above.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a composite buried pipe ground-source heat pump system and an optimization method thereof. By constructing a cooling and heating load ratio and calculating the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe under the dominant load ratio, the levelized energy cost is obtained based on the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe. With the goal of minimizing the levelized energy cost, the final pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe are obtained. The final pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe can ensure the long-term and efficient operation of the composite buried pipe ground-source heat pump system at a relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a flow chart of an optimization method for a composite buried pipe ground-source heat pump system provided in Example 1 of the present invention;

[0046] Figure 2 This is a connection diagram of a composite buried pipe ground source heat pump system provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0048] Example 1:

[0049] like Figure 1 As shown, an embodiment of the present invention provides an optimization method for a composite buried pipe ground source heat pump system, the composite buried pipe ground source heat pump system including a vertical buried pipe heat pump system and a horizontal spiral buried pipe heat pump system, the optimization method comprising:

[0050] 1. Obtain the cooling and heating loads of the building, and based on the cooling and heating loads of the building, obtain the peak cooling and heating loads of the building and the cumulative cooling and heating loads of the building.

[0051] 2. Determine whether the building's cooling and heating load is the dominant load or non-dominant load based on the building's cumulative cooling and heating load;

[0052] If the cumulative cooling load is greater than the cumulative heating load, the building cooling load is the dominant load and the building heating load is the non-dominant load; if the cumulative cooling load is less than or equal to the cumulative heating load, the building heating load is the dominant load and the building cooling load is the non-dominant load.

[0053] 3. Define the dominant load ratio and non-dominant load ratio based on the ratio of the maximum cooling and heating load borne by the vertical buried pipe heat pump system to the building's peak cooling and heating load;

[0054] The dominant load ratio α, α∈[0,1] is the ratio of the maximum dominant load borne by the vertical buried pipe heat pump system to the peak dominant load of the building; the non-dominant load ratio β, β∈[0,1] is the ratio of the maximum non-dominant load borne by the vertical buried pipe heat pump system to the peak non-dominant load of the building.

[0055] 4. Based on the pre-built vertical buried pipe length design equation, iteratively solve the defined dominant load ratio, non-dominant load ratio, and the corresponding vertical buried pipe length required for the vertical buried pipe heat pump system;

[0056] Specifically include:

[0057] Step S1, initializing the dominant load ratio α=0, and the non-dominant load ratio β=1;

[0058] Step S2: Obtain the maximum cooling and heating load of the vertical buried pipe heat pump system according to the product of the dominant load ratio α, the non-dominant load ratio β and the peak cooling and heating load of the building;

[0059] Determine whether the maximum cooling and heating load of the vertical buried pipe heat pump system is greater than or equal to the cooling and heating load of the building;

[0060] If so, the vertical buried pipe heat pump system bears the cooling and heating loads of the building; if not, the vertical buried pipe heat pump system and the horizontal buried pipe heat pump system jointly bear the cooling and heating loads of the building, and the horizontal buried pipe heat pump system bears the part of the maximum cooling and heating load of the vertical buried pipe heat pump system that is less than the cooling and heating load of the building.

[0061] Step S3: Calculate the required vertical buried pipe lengths for the vertical buried pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-established vertical buried pipe length design equations;

[0062] The pre-built vertical buried pipe length design equation is:

[0063]

[0064] Among them, L cooling .BHE and L heating .BHE are the lengths of vertical buried pipes required for the vertical buried pipe heat pump system in cooling and heating conditions, respectively, and q net is the net geothermal energy injected / extracted by vertical buried pipes throughout the year, R sa 、R sm 、R sst are the soil thermal resistance under continuous pulse load at preset time, month and year cycles, R b is the drilling thermal resistance, PLF m is the operating share of cooling and heating conditions in the corresponding month, F sc Thermal short-circuit loss factor caused by thermal interaction between the inlet and outlet pipes, T0 is the initial soil temperature, ELT and LLT are the rated inlet and outlet water temperatures of the heat pump unit, respectively, T p is the soil penalty temperature caused by all thermal interactions between water pipes, q cond and q evap They are the maximum cooling and heating loads of the vertical buried pipe heat pump system corresponding to cooling and heating conditions respectively.

[0065] Step S4: taking the larger value of the vertical buried pipe lengths required for the vertical buried pipe heat pump system in cooling and heating conditions as the required vertical buried pipe length for the vertical buried pipe heat pump system;

[0066] Step S5: Calculate the difference based on the lengths of the vertical buried pipes required for cooling and heating conditions, and determine whether the relative difference is greater than a preset difference value. If so, reduce the non-dominant load ratio β by a preset decreasing step size, and bring the above step S2 into iteration;

[0067] Step S6: If not, output the current dominant load ratio α and non-dominant load ratio β, increase the dominant load ratio α by a preset incremental step, and return to the above step S2 for iteration.

[0068] 5. Based on the pre-built trench design equation for horizontal spiral underground pipes and the solved dominant load ratio and non-dominant load ratio, calculate the trench length of the horizontal spiral underground pipe heat pump system required;

[0069] Specifically include:

[0070] S1. Obtain the maximum cooling and heating load of the horizontal spiral buried pipe heat pump system according to the product of the solved dominant load ratio α, the non-dominant load ratio β and the peak cooling and heating load of the building;

[0071] S2. Calculate the trench lengths of the horizontal spiral underground pipes required for the horizontal spiral underground pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-established trench design equations for the horizontal spiral underground pipes.

[0072] The trench design equation for the pre-built horizontal spiral buried pipe is:

[0073]

[0074] Among them, L cooling .HGHE and L heating HGHE are the trench lengths of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system in cooling and heating conditions, respectively. net is the net geothermal energy injected / extracted by the horizontal spiral buried pipe throughout the year, R sa 、R sm 、R sst are the soil thermal resistance under continuous pulse load at preset time, month and year cycles, R p is the buried pipe thermal resistance, PLF m is the operating share of cooling and heating conditions in the corresponding month, F sc The thermal short-circuit loss factor caused by the thermal interaction between the inlet and outlet water pipes, ELT and LLT are the rated inlet and outlet water temperatures of the heat pump unit, T p is the soil penalty temperature caused by all thermal interactions between water pipes, T H,cooling and T H,heating are the maximum temperature value of the soil depth at the center axis of the horizontal spiral buried pipe in the cooling condition and the minimum temperature value of the heating condition, respectively.cond and q evap are the maximum cooling and heating loads of the horizontal spiral underground pipe heat pump system corresponding to cooling and heating conditions respectively;

[0075] S3. Take the larger value of the trench length of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system in cooling and heating conditions as the trench length of the horizontal spiral underground pipe.

[0076] 6. Obtain the investment cost, operating cost, maintenance cost, and heat transfer based on the length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe under the determined dominant load ratio and non-dominant load ratio;

[0077] The investment cost, operating cost, and maintenance cost are obtained based on preset calculation rules according to the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe. The heat transfer rate is obtained based on the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe based on pre-built simulation software.

[0078] 7. Calculate the levelized cost of energy based on investment cost, operating cost, maintenance cost and heat transfer;

[0079] The levelized cost of energy is:

[0080]

[0081] Among them, LCoE is the levelized cost of energy, IC is the investment cost, OC is the y is the operating cost in year y, MC y is the maintenance cost in year y, Q y is the heat transferred in year y, IR is the interest rate, and Y is the total number of years.

[0082] 8. With the goal of minimizing the levelized cost of energy, obtain the final length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe.

[0083] Example 2:

[0084] Take the building cooling load as the dominant load and the building heating load as the non-dominant load as an example:

[0085] 1. Define the cooling load ratio α, α∈[0,1] as the ratio of the maximum cooling load borne by the vertical buried pipe heat pump system to the peak cooling load of the building; the heating load ratio β, β∈[0,1] as the ratio of the maximum heating load borne by the vertical buried pipe heat pump system to the peak heating load of the building.

[0086] 2. Obtain the maximum cooling load of the vertical ground pipe heat pump system based on the product of the cooling load ratio α and the peak cooling load of the building; determine whether the maximum cooling load of the vertical ground pipe heat pump system is greater than or equal to the cooling load of the building; if so, the vertical ground pipe heat pump system bears the cooling load of the building; if not, the vertical ground pipe heat pump system and the horizontal ground pipe heat pump system jointly bear the cooling load of the building, and the horizontal ground pipe heat pump system bears the portion of the maximum cooling load of the vertical ground pipe heat pump system that is less than the cooling load of the building.

[0087] 3. Obtain the maximum heat load of the vertical buried pipe heat pump system based on the product of the heat load ratio β and the peak heat load of the building; determine whether the maximum heat load of the vertical buried pipe heat pump system is greater than or equal to the heat load of the building; if so, the vertical buried pipe heat pump system bears the heat load of the building; if not, the vertical buried pipe heat pump system and the horizontal buried pipe heat pump system jointly bear the heat load of the building, and the horizontal buried pipe heat pump system bears the portion of the maximum heat load of the vertical buried pipe heat pump system that is less than the heat load of the building.

[0088] 4. Based on the pre-built vertical buried pipe length design equation, iteratively solve the defined cooling load ratio, heating load ratio, and the corresponding vertical buried pipe length required for the vertical buried pipe heat pump system;

[0089] S1, initialize the cooling load ratio α = 0, the heating load ratio β = 1;

[0090] S2. Obtain the maximum cooling and heating loads of the vertical buried pipe heat pump system according to the product of the cooling load ratio α, the heating load ratio β, and the peak cooling and heating loads of the building;

[0091] S3. Calculate the required vertical buried pipe lengths for the vertical buried pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-established vertical buried pipe length design equations.

[0092] S4. Take the larger value of the vertical buried pipe lengths required for the vertical buried pipe heat pump system in cooling and heating conditions as the required vertical buried pipe length for the vertical buried pipe heat pump system;

[0093] S5. Calculate the difference based on the lengths of the vertical buried pipes required for cooling and heating conditions, and determine whether the relative difference is greater than a preset difference value. If so, decrease the heat load ratio β by a decreasing step size of Δβ=-0.01, and iterate the above steps.

[0094] S6. If not, output the current cooling load ratio α and heating load ratio β, increase the cooling load ratio α with Δα=0.01 as the incremental step, and bring it into the above steps for iteration.

[0095] 5. Based on the pre-built trench design equation for horizontal spiral underground pipes and the solved cooling load ratio and heating load ratio, calculate the trench length of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system;

[0096] Specifically include:

[0097] S1. Obtain the maximum cooling and heating loads of the horizontal spiral underground pipe heat pump system based on the product of the solved cooling load ratio α, heating load ratio β and the building's peak cooling and heating loads;

[0098] S2. Calculate the trench lengths of the horizontal spiral underground pipes required for the horizontal spiral underground pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-established trench design equations for the horizontal spiral underground pipes.

[0099] S3. Take the larger value of the trench length of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system in cooling and heating conditions as the trench length of the horizontal spiral underground pipe.

[0100] 6. Obtain the investment cost, operating cost, maintenance cost, and heat transfer value based on the calculated cooling load ratio and heating load ratio for the vertical buried pipe length and the horizontal spiral buried pipe trench length;

[0101] Investment costs include drilling costs, excavation costs, pipe costs, backfill material costs, equipment costs and labor costs; operating costs include the electricity costs required for the operation of the heat pump unit, the electricity costs required for the operation of the load side and ground source side water pumps, and the electricity costs required for the operation of the terminal device; maintenance costs include maintenance, pipe section cleaning and other costs.

[0102] The heat transfer rate is calculated by simulation software and analytical solution model for the hourly heat transfer rate of vertical and horizontal composite buried pipes under different combinations of vertical buried pipe lengths and horizontal spiral buried pipe trench lengths. It is necessary to pay attention to the coupling relationship between buried pipe load, heat pump unit COP and building load.

[0103] 7. Calculate the levelized cost of energy based on investment cost, operating cost, maintenance cost and heat transfer;

[0104] 8. With the goal of minimizing the levelized cost of energy, obtain the final length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe.

[0105] Example 3:

[0106] like Figure 2As shown, an embodiment of the present invention provides a composite buried pipe ground source heat pump system, including a vertical buried pipe heat pump system and a horizontal spiral buried pipe heat pump system, the vertical buried pipe heat pump system includes a vertical buried pipe heat pump unit, the ground source side of the vertical buried pipe heat pump unit is connected in series with a vertical buried pipe group, a first ground source side water pump and a first ground source side valve, and the vertical buried pipe group includes multiple parallel vertical buried pipes; the horizontal spiral buried pipe heat pump system includes a horizontal spiral buried pipe heat pump unit, the ground source side of the horizontal spiral buried pipe heat pump unit is connected in series with a horizontal spiral buried pipe group, a second ground source side water pump and a second ground source side valve, and the horizontal spiral buried pipe group includes multiple parallel horizontal spiral buried pipes; the load side of the composite buried pipe ground source heat pump system includes a load and a load side water pump, and the load sides of the vertical buried pipe heat pump unit and the horizontal spiral buried pipe heat pump unit are both connected in series with the load and the load side water pump. The composite buried pipe ground source heat pump system adopts the optimization method of the composite buried pipe ground source heat pump system as described in the first embodiment.

[0107] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for optimizing a composite buried pipe ground source heat pump system, wherein the composite buried pipe ground source heat pump system comprises a vertical buried pipe heat pump system and a horizontal spiral buried pipe heat pump system, characterized in that: The optimization method comprises: Obtaining the cooling and heating loads of the building, and obtaining the peak cooling and heating loads of the building and the cumulative cooling and heating loads of the building based on the cooling and heating loads of the building; Determine whether the building's cooling and heating load is a dominant load or a non-dominant load based on the building's cumulative cooling and heating load; The dominant load ratio and non-dominant load ratio are defined based on the ratio of the maximum cooling and heating load borne by the vertical buried pipe heat pump system to the peak cooling and heating load of the building; Based on the pre-built vertical buried pipe length design equation, the defined dominant load ratio, non-dominant load ratio and the corresponding vertical buried pipe length required for the vertical buried pipe heat pump system are iteratively solved; Based on the pre-built trench design equation for horizontal spiral underground pipes, the trench length required for the horizontal spiral underground pipe heat pump system is calculated according to the solved dominant load ratio and non-dominant load ratio; The investment cost, operation cost, maintenance cost and heat transfer are obtained based on the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe under the solved dominant load ratio and non-dominant load ratio; Calculate the levelized cost of energy based on investment cost, operating cost, maintenance cost and heat transfer; With the goal of minimizing the levelized cost of energy, the final length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe are obtained.

2. The optimization method of a composite buried pipe ground source heat pump system according to claim 1, characterized in that: The determining whether the building's cooling and heating load is a dominant load or a non-dominant load based on the building's cumulative cooling and heating loads includes: If the cumulative cooling load is greater than the cumulative heating load, the building cooling load is the dominant load and the building heating load is the non-dominant load; if the cumulative cooling load is less than or equal to the cumulative heating load, the building heating load is the dominant load and the building cooling load is the non-dominant load.

3. The optimization method of a composite buried pipe ground source heat pump system according to claim 1, characterized in that: The dominant load ratio α, α∈[0,1] is the ratio of the maximum dominant load borne by the vertical buried pipe heat pump system to the peak dominant load of the building; the non-dominant load ratio β, β∈[0,1] is the ratio of the maximum non-dominant load borne by the vertical buried pipe heat pump system to the peak non-dominant load of the building.

4. The optimization method of a composite buried pipe ground source heat pump system according to claim 3, characterized in that: The iterative solution of the defined dominant load ratio, the non-dominant load ratio, and the corresponding vertical buried pipe length required for the vertical buried pipe heat pump system includes: Step S1, initializing the dominant load ratio α=0, and the non-dominant load ratio β=1; Step S2: Obtain the maximum cooling and heating load of the vertical buried pipe heat pump system according to the product of the dominant load ratio α, the non-dominant load ratio β and the peak cooling and heating load of the building; Step S3: Calculate the required vertical buried pipe lengths for the vertical buried pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-established vertical buried pipe length design equations; Step S4: taking the larger value of the vertical buried pipe lengths required for the vertical buried pipe heat pump system in cooling and heating conditions as the required vertical buried pipe length for the vertical buried pipe heat pump system; Step S5: Calculate the difference based on the lengths of the vertical buried pipes required for cooling and heating conditions, and determine whether the relative difference is greater than a preset difference value. If so, reduce the non-dominant load ratio β by a preset decreasing step size, and bring the above step S2 into iteration; Step S6: If not, output the current dominant load ratio α and non-dominant load ratio β, increase the dominant load ratio α by a preset incremental step, and return to the above step S2 for iteration.

5. The optimization method of a composite buried pipe ground source heat pump system according to claim 4, characterized in that: The obtaining of the maximum cooling and heating loads of the vertical buried pipe heat pump system further includes: Determine whether the maximum cooling and heating load of the vertical buried pipe heat pump system is greater than or equal to the cooling and heating load of the building; If so, the vertical buried pipe heat pump system bears the cooling and heating loads of the building; if not, the vertical buried pipe heat pump system and the horizontal buried pipe heat pump system jointly bear the cooling and heating loads of the building, and the horizontal buried pipe heat pump system bears the part of the maximum cooling and heating load of the vertical buried pipe heat pump system that is less than the cooling and heating load of the building.

6. The optimization method of a composite buried pipe ground source heat pump system according to claim 4, characterized in that: The pre-built vertical buried pipe length design equation is: Among them, L cooling .BHE and L heating .BHE are the lengths of vertical buried pipes required for the vertical buried pipe heat pump system in cooling and heating conditions, respectively, and q net is the net geothermal energy injected / extracted by vertical buried pipes throughout the year, R sa 、R sm 、R sst are the soil thermal resistance under continuous pulse load at preset time, month and year cycles, R b is the drilling thermal resistance, PLF m is the operating share of cooling and heating conditions in the corresponding month, F sc Thermal short-circuit loss factor caused by thermal interaction between the inlet and outlet pipes, T0 is the initial soil temperature, ELT and LLT are the rated inlet and outlet water temperatures of the heat pump unit, respectively, T p is the soil penalty temperature caused by all thermal interactions between water pipes, q cond and q evap They are the maximum cooling and heating loads of the vertical buried pipe heat pump system corresponding to cooling and heating conditions respectively.

7. The optimization method of a composite buried pipe ground source heat pump system according to claim 1, characterized in that: The calculation of the trench length of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system includes: The maximum cooling and heating loads of the horizontal spiral buried pipe heat pump system are obtained by multiplying the solved dominant load ratio α, non-dominant load ratio β and the building's peak cooling and heating loads. Calculate the required trench length for the horizontal spiral underground pipe heat pump system under cooling and heating conditions based on the maximum cooling and heating loads and the pre-built trench design equation for the horizontal spiral underground pipe. The trench design equation for the pre-built horizontal spiral buried pipe is: Among them, L cooling .HGHE and L heating HGHE are the trench lengths of the horizontal spiral underground pipe required for the horizontal spiral underground pipe heat pump system in cooling and heating conditions, respectively. net is the net geothermal energy injected / extracted by the horizontal spiral buried pipe throughout the year, R sa 、R sm 、R sst are the soil thermal resistance under continuous pulse load at preset time, month and year cycles, R p is the buried pipe thermal resistance, PLF m is the operating share of cooling and heating conditions in the corresponding month, F sc The thermal short-circuit loss factor caused by the thermal interaction between the inlet and outlet water pipes, ELT and LLT are the rated inlet and outlet water temperatures of the heat pump unit, T p is the soil penalty temperature caused by all thermal interactions between water pipes, T H,cooling and T H,heating are the maximum temperature value of the soil depth at the center axis of the horizontal spiral buried pipe in the cooling condition and the minimum temperature value of the heating condition, respectively. cond and q evap are the maximum cooling and heating loads of the horizontal spiral underground pipe heat pump system corresponding to cooling and heating conditions respectively; The larger value of the trench length of the horizontal spiral buried pipe required for the horizontal spiral buried pipe heat pump system under cooling and heating conditions is taken as the trench length of the horizontal spiral buried pipe.

8. The optimization method of a composite buried pipe ground source heat pump system according to claim 1, characterized in that: The investment cost, operating cost and maintenance cost are obtained based on preset calculation rules according to the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe; the heat transfer amount is obtained based on the pipe length of the vertical buried pipe and the trench length of the horizontal spiral buried pipe based on pre-built simulation software.

9. The optimization method of a composite buried pipe ground source heat pump system according to claim 1, characterized in that: The levelized cost of energy is: Among them, LCoE is the levelized cost of energy, IC is the investment cost, OC is the y is the operating cost in year y, MC y is the maintenance cost in year y, Q y is the heat transferred in year y, IR is the interest rate, and Y is the total number of years.

10. A composite buried pipe geothermal heat pump system, comprising a vertical buried pipe heat pump system and a horizontal spiral buried pipe heat pump system, wherein the vertical buried pipe heat pump system comprises a vertical buried pipe heat pump unit, wherein the ground source side of the vertical buried pipe heat pump unit is connected in series with a vertical buried pipe group, a first ground source side water pump and a first ground source side valve, and the vertical buried pipe group comprises a plurality of parallel vertical buried pipes; the horizontal spiral buried pipe heat pump system comprises a horizontal spiral buried pipe heat pump unit, wherein the ground source side of the horizontal spiral buried pipe heat pump unit is connected in series with a horizontal spiral buried pipe group, a second ground source side water pump and a second ground source side valve, and the horizontal spiral buried pipe group comprises a plurality of parallel horizontal spiral buried pipes; characterized in that The composite buried pipe ground source heat pump system adopts an optimization method for a composite buried pipe ground source heat pump system as described in any one of claims 1 to 9.

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