CN102855414A - Efficient calculating method for parametrization design of vertical ground heat exchanger - Google Patents
Efficient calculating method for parametrization design of vertical ground heat exchanger Download PDFInfo
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- CN102855414A CN102855414A CN2012103571778A CN201210357177A CN102855414A CN 102855414 A CN102855414 A CN 102855414A CN 2012103571778 A CN2012103571778 A CN 2012103571778A CN 201210357177 A CN201210357177 A CN 201210357177A CN 102855414 A CN102855414 A CN 102855414A
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Abstract
The invention discloses an efficient calculating method for parametrization design of a vertical ground heat exchanger. According to the efficient calculating method provided by the invention, the method comprises the steps of expressing the hourly heat absorbing and radiating heat flow of the vertical ground heat exchanger of a heat pump system as a rectangular pulse heat flow sequence; introducing a concept of underground rock dimensionless transient temperature response g function under the effect of unit rectangular pulse heat flow, so as to obtain the function with the integrating interval of [0, deltaF0]; and taking drill parameters into design calculation, so that the calculating result is accurate and reliable, the calculation time is greatly shortened, and the efficient calculation method is provided for achieving the parametrization design of the vertical ground heat exchanger.
Description
Technical field
The present invention relates to the earth source heat pump field, particularly a kind of efficient calculation method of vertical ground heat exchanger Parametric designing.
Background technology
In earth source heat pump, vertical buried pipe type water loop heat pump system more and more is widely used because underground ground temperature field is stable, energy efficiency is high.It mainly is used in the heating air conditioning and hot water supply system of all kinds of buildings.Vertical ground heat exchanger construction cost is high, and design of heat exchanger is crossed conference and caused initial cost waste, operating cost high; Design of heat exchanger is less than normal then can not to guarantee heat pump stable operation, can not satisfy the demand of system's suction heat, reduces running efficiency of system.When design water loop heat pump system, the designing and calculating of vertical ground heat exchanger is very crucial.
The heat pump runtime is generally 10-30.In order to design the vertical ground heat exchanger of appropriate size, need to according to heat pump in the runtime by the time suction calorimeter calculate in the vertical ground heat exchanger pipe by the time fluid temperature (F.T.), underground ground by the time transient temperature, whether can satisfy the suction heat demand of heat pump within the runtime with the size of assessment heat interchanger.
The designing and calculating parameter of vertical ground heat exchanger is many, must just can design by Parametric designing the ground heat exchanger of suitable size.Present mostly employing g functional based method calculates fluid temperature (F.T.) when pursuing in the pipe of ground heat exchanger within the runtime, transient temperature when underground ground pursues.So-called g function is exactly single vertical drilling ground heat exchanger pipe surface temperature and response of underground ground dimensionless transient temperature under the effect of unit hot-fluid.Had g functional value and heat pump within the runtime by the time suction heat, by drilling well superposition and convolution or frequency domain Fast Fourier Transform (FFT) (FFT) just can try to achieve the drilling well group within the runtime Tube Sheet of Heat Exchanger wall temperature and underground ground transient temperature pursue duration.The g function can be the data form that goes out with numerical calculations; Also can be the analytic solution of single drilling well being regarded as Tube Sheet of Heat Exchanger wall temperature and the underground ground transient temperature response under unit hot-fluid effect of limited line heat source, infinite line thermal source and cylinder thermal source.Regardless of being with numerical method or using analytic method, calculate the g function and need to consume the plenty of time by duration.Generally be first with the g function calculation of different drilling parameters out, when designing and calculating by tabling look-up and interpolation method obtains g functional value under the drilling well calculating parameter.It also is very consuming time that convolution calculates.So there is the expert to propose the methods such as " load aggregation method " (Load aggregation method) based on the g function and Fourier transform Spline Method (FFT-s) to reduce computing time.With limited line source model analytic expression g function designing and calculating ground heat exchanger, for example calculate one group of parameter of 30 year runtime of 40 drilling wells, with the time of time domain convolutional calculation needs more than 1 day, also need more than 2 hour (containing the time of calculating the g function) with FFT calculating.The drilling well group has many groups of parameter configuration to calculate, and storing the g functional value with the data form form needs a very large database, and the database that precomputes is difficult to comprise the four corner of the related whole parameters of designing and calculating.On the other hand, no matter be to table look-up to obtain the g functional value with interpolation, the methods such as still " load aggregation method " (Load aggregation method) and Fourier transform Spline Method (FFT-s) all can be brought than the computation error.Therefore, be difficult to realize the Parametric designing of vertical ground heat exchanger with g function and derivative computing method thereof.
Summary of the invention
Technical matters to be solved by this invention is, and is not enough for prior art, and a kind of efficient calculation method of vertical ground heat exchanger Parametric designing is provided, and guarantees result of calculation accurately and reliably, greatly reduces computing time.
For solving the problems of the technologies described above, the technical solution adopted in the present invention is: a kind of efficient calculation method of vertical ground heat exchanger Parametric designing, and the method may further comprise the steps:
1) can use floor area according to vertical ground heat exchanger drilling well group, tentatively choose one group of drilling parameter configuration: the wells spacing parameter
D, offset distance
x, and the drilling well number
N, boring radius
r b , drilling depth
H, the ground coefficient of heat conductivity
k s , the ground thermal diffusion coefficient
, need design-calculated heat pump operation year number
n
2) with in the earth-source hot-pump system need to by ground heat exchanger from underground extraction or enter each hour underground 1 year heat constantly divided by (
H N) after, the square pulse of conductive heat flow when the unit's of being expressed as vertical shaft length is pursued [(
Q (t 1 ), q (
t 2 ), q (
t 3 ) ..., q (
t 8760)];
3) underground any degree of depth of utilizing the limited line source model of single drilling well under the effect of unit step hot-fluid, to derive
z(or
h) and radius distance (
r) response of dimensionless transient temperature
gThe analytical form of function:
In the formula,
, be called Fourier's time;
Be the time;
Erfc (z)Be complementary error function,
Ask formula (1)
gFunction is to Fourier's time variable
FoPartial derivative, have
Obtain underground any degree of depth and radius distance
gAnother analytical form of function:
4), opposite direction identical with two sizes, time phase difference
Step hot-fluid stack obtain the rect.p. hot-fluid, definition
Function is single drilling well underground any degree of depth and response of radius distance dimensionless transient temperature under unit rect.p. hot-fluid effect, so,
The function analytical form is:
In the formula,
Be Fourier's time step,
Be time step, in designing and calculating, be taken as 1 hour, so, drilling well wall neutral temperature
Function is:
(5)
5) neutral temperature of arbitrary borehole wall and medial temperature in the selected drilling well in the step 1)
Function is respectively:
(8)
Underground ground initial temperature is
, rect.p. hot-fluid sequence [(
q(
t 1 ),
q(
t 2 ),
q(
t 3 ) ... ] effect under, the relative transient temperature of the underground any degree of depth of single drilling well and radius distance is:
When
The time, being the borehole wall surface temperature, the boring relative transient state neutral temperature of wall and medial temperature are:
6) obtain each temperature or each temperature constantly of boring wall constantly of underground ground by relative transient temperature, calculate the boring internal thermal resistance of single U-shaped and double u-tube with fluid medial temperature method
R b , each tube fluid temperature constantly of ground heat exchanger so
Be calculated as follows:
By the Performance Ratio of fluid temperature (F.T.) and heat pump, calculate the energy consumption of heat pump;
7) for different drilling parameter combinations, repeat above-mentioned calculation procedure, calculate drilling well total length, borehole wall surface temperature and the tube fluid temperature of respectively organizing parameter; By drilling well total length, borehole wall surface temperature and tube fluid temperature, subsurface temperature variation range, cost, heat pump energy consumption and the reciprocation cycle under the parameter respectively organized in assessment, selects the vertical ground heat exchanger parameter, is the vertical ground heat exchanger of design.
Compared with prior art, the beneficial effect that has of the present invention is: the present invention by introduce underground ground dimensionless transient temperature response under the unit rect.p. hot-fluid effect-
The concept of function, obtain its integrating range for [0,
]
Function can be brought drilling parameter into designing and calculating, guarantees result of calculation accurately and reliably, has greatly reduced computing time again, for the vertical ground heat exchanger Parametric designing provides a kind of efficient computing method.
Description of drawings
Fig. 1 be one embodiment of the invention creep into group and creep between apart from schematic diagram;
Fig. 2 is that one embodiment of the invention unit length ground heat exchanger hot-fluid is by the rect.p. presentation graphs of duration;
Fig. 3 is that one embodiment of the invention obtains rect.p. hot-fluid schematic diagram with two step hot-fluid stacks;
Fig. 4 is the single drilling well wall of one embodiment of the invention medial temperature
Function curve diagram;
Fig. 5 is the suction heat schematic diagram of every meter heat interchanger of one embodiment of the invention heat pump;
Fig. 6 is the wall medial temperature curve map of the 1st drilling well of one embodiment of the invention;
Fig. 7 is the fluid temperature (F.T.) curve map of one embodiment of the invention ground heat exchanger outlet.
Embodiment
One embodiment of the invention method step is as follows:
1. as shown in Figure 1, can use floor area according to vertical ground heat exchanger drilling well group, tentatively choose one group of drilling parameter configuration: the wells spacing parameter
D, offset distance
x, and the drilling well number
N(
N=
m n,
mWith
nBe columns anyhow), boring radius
r b , drilling depth
H, the ground coefficient of heat conductivity
k s , the ground thermal diffusion coefficient
, need design-calculated heat pump operation year number
n
With in the earth-source hot-pump system need to by ground heat exchanger from underground extraction or enter underground 1 year each constantly heat divided by (
H N) after, the square pulse of conductive heat flow when the unit's of being expressed as vertical shaft length is pursued [(
Q (t 1 ), q (
t 2 ), q (
t 3 ) ..., q (
t 8760)], as shown in Figure 2.With the rect.p. hot-fluid sequence in 1 year repeat to extend rect.p. hot-fluid sequence for n 8760.
3. underground any degree of depth of utilizing the limited line source model of single drilling well under the effect of unit step hot-fluid, to derive
z(or
h) and radius distance
rThe response of dimensionless transient temperature
gThe analytical form of function:
In the formula,
, be called Fourier's time;
Be the time;
Erfc (z)Be complementary error function,
Ask formula (1)
gFunction is to Fourier's time variable
FoPartial derivative, have
Obtain underground any degree of depth and radius distance
gAnother analytical form of function.
4. as shown in Figure 3, any time
The rect.p. hot-fluid can be identical by 2 sizes, opposite direction, time phase difference
Step heat transfer capacity stack obtain.Definition
Function is single drilling well underground any degree of depth and response of radius distance dimensionless transient temperature under unit rect.p. hot-fluid effect.So,
The function analytical form is:
In the formula,
Be Fourier's time step,
Be time step, in designing and calculating, be taken as 1 hour.So, drilling well wall neutral temperature
Function is:
The single drilling well wall medial temperature of typical case
Function as shown in Figure 4.The integrating range of formula (4), (5) and (6) be [0,
], be about 1 10/1000000ths of formula (1) integrating range [0,1]
-6Doubly).Thereby,
Ratio computing time of function
gThe computing time of function is little a lot, thereby has greatly accelerated computing velocity.
5. for the drilling well group of Fig. 1, drilling well
eThe mid point of hole wall and medial temperature
Function is respectively:
Underground ground initial temperature is
, rect.p. hot-fluid sequence [(
q(
t 1 ),
q(
t 2 ),
q(
t 3 ) ... ] effect under, the relative transient temperature of the underground any degree of depth of single drilling well and radius distance is:
When
The time, be the borehole wall surface temperature.Boring among the boring group
eThe relative transient state neutral temperature of wall and medial temperature are:
In the formula,
Initial temperature for underground ground.Formula (9), (10) and (11) are the calculating formulas of convolution, adopt FFT to calculate convolution and can further improve computing velocity.
6. can get each temperature or each temperature constantly of boring wall constantly of underground ground by relative transient temperature, calculate the boring internal thermal resistance of single U-shaped and double u-tube with fluid medial temperature method or additive method
R b , each tube fluid temperature constantly of ground heat exchanger so
Be calculated as follows:
Can by the Performance Ratio of fluid temperature (F.T.) and heat pump, calculate the energy consumption of heat pump.
7. for different drilling parameter combination (parameters
Dx,
Dy,
x,
H,
r b ,
m,
n,
k s ,
, list or double u-tube etc.), repeat above-mentioned calculation procedure, calculate drilling well total length, borehole wall surface temperature and the tube fluid temperature etc. of respectively organizing parameter.By data such as drilling well total length, borehole wall surface temperature and tube fluid temperature, subsurface temperature variation range, cost, heat pump energy consumption and the reciprocation cycle etc. under the parameter are respectively organized in assessment, to select the rational vertical ground heat exchanger parameter of economy, be the vertical ground heat exchanger of design.
Demonstrate computing method of the present invention below by the computation process to one 58 (m=5, n=8) drilling well group's vertical ground heat exchanger.If wells spacing is
Dx=Dy=5m, deviation distance
x=0m, drilling depth
H=60m, the drilling well radius
r b =0.055m,
=18.5 ℃,
k s =2.3W/ (m ℃),
A=1.25 10
-6(m
2/ s), time step
Be 1 hour (3600s).Load when pursuing in 1 year with the synthetic heat pump of formula (14)
Q(W/m), and be expressed as the suction hot-fluid of unit length heat interchanger, as shown in Figure 5.
In the formula
A=-4.25 W/m,
B=25 W/m,
C=12.5 W/m,
D=6.25 W/m.
The variation in 30 years of the flat temperature of wall of the 1st drilling well of drilling well group that calculates, as shown in Figure 6.Get the thermal resistance in the drilling well
R b =0.087m
2℃/W, the variation in 30 years of the ground heat exchanger that calculates outlet fluid temperature (F.T.), shown in Figure 7.
Claims (1)
1. the efficient calculation method of a vertical ground heat exchanger Parametric designing is characterized in that, the method may further comprise the steps:
1) can use floor area according to vertical ground heat exchanger drilling well group, tentatively choose one group of drilling parameter configuration: the wells spacing parameter
D, offset distance
x, and the drilling well number
N, boring radius
r b , drilling depth
H, the ground coefficient of heat conductivity
k s , the ground thermal diffusion coefficient
, need design-calculated heat pump operation year number
n
2) with in the earth-source hot-pump system need to by ground heat exchanger from underground extraction or enter each hour underground 1 year heat constantly divided by (
H N) after, the square pulse of conductive heat flow when the unit's of being expressed as vertical shaft length is pursued [(
Q (t 1 ), q (
t 2 ), q (
t 3 ) ..., q (
t 8760)];
3) underground any degree of depth of utilizing the limited line source model of single drilling well under the effect of unit step hot-fluid, to derive
zOr
hAnd radius distance
rThe response of dimensionless transient temperature
gThe analytical form of function:
In the formula,
, be called Fourier's time;
Be the time;
Erfc (z)Be complementary error function,
Ask formula (1)
gFunction is to Fourier's time variable
FoPartial derivative, have
Obtain underground any degree of depth and radius distance
gAnother analytical form of function:
4), opposite direction identical with two sizes, time phase difference
Step hot-fluid stack obtain the rect.p. hot-fluid, definition
Function is single drilling well underground any degree of depth and response of radius distance dimensionless transient temperature under unit rect.p. hot-fluid effect, so,
The function analytical form is:
In the formula,
Be Fourier's time step,
Be time step, in designing and calculating, be taken as 1 hour, so, drilling well wall neutral temperature
Function is:
5) neutral temperature of arbitrary borehole wall and medial temperature in the selected drilling well in the step 1)
Function is respectively:
(7)
Underground ground initial temperature is
, rect.p. hot-fluid sequence [(
q(
t 1 ),
q(
t 2 ),
q(
t 3 ) ... ] effect under, the relative transient temperature of the underground any degree of depth of single drilling well and radius distance is:
When
The time, being the borehole wall surface temperature, the boring relative transient state neutral temperature of wall and medial temperature are:
(10)
6) obtain each temperature or each temperature constantly of boring wall constantly of underground ground by relative transient temperature, calculate the boring internal thermal resistance of single U-shaped and double u-tube with fluid medial temperature method
R b , each tube fluid temperature constantly of ground heat exchanger so
Be calculated as follows:
By the Performance Ratio of fluid temperature (F.T.) and heat pump, calculate the energy consumption of heat pump;
7) for different drilling parameter combinations, repeat above-mentioned calculation procedure, calculate drilling well total length, borehole wall surface temperature and the tube fluid temperature of respectively organizing parameter.
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Cited By (8)
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CN103235860A (en) * | 2013-05-07 | 2013-08-07 | 北京工业大学 | Hole wall representation temperature based simulation design method for drill hole space |
CN106354984A (en) * | 2016-10-21 | 2017-01-25 | 山东中瑞新能源科技有限公司 | Temperature response calculation method of pile foundation spiral buried pipe under condition of underground water seepage |
CN107145705A (en) * | 2017-03-29 | 2017-09-08 | 中国海洋石油总公司 | A kind of method and device for obtaining circulating temperature |
CN107391807A (en) * | 2017-06-28 | 2017-11-24 | 西安交通大学 | Plate-fin heat exchanger heat transfer flow performance value analogy method based on transient technology |
CN109948182A (en) * | 2019-01-30 | 2019-06-28 | 西安交通大学 | A kind of calculation method for mid-deep strata geothermal well well spacing |
CN111539130A (en) * | 2020-05-29 | 2020-08-14 | 山东建筑大学 | Design and calculation method for drilling depth of geothermal heat exchanger of middle-deep buried pipe |
CN112487527A (en) * | 2020-11-25 | 2021-03-12 | 浙江工业大学 | Design method of solar ground source heat pump heat supply and air conditioning system |
CN113343444A (en) * | 2021-05-24 | 2021-09-03 | 河南中烟工业有限责任公司 | Structural design method of double-U-shaped cold and hot dual-purpose ground heat exchanger |
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CN103235860A (en) * | 2013-05-07 | 2013-08-07 | 北京工业大学 | Hole wall representation temperature based simulation design method for drill hole space |
CN103235860B (en) * | 2013-05-07 | 2016-01-20 | 北京工业大学 | The emulation design method of spacing between a kind of boring based on hole wall representation temperature |
CN106354984A (en) * | 2016-10-21 | 2017-01-25 | 山东中瑞新能源科技有限公司 | Temperature response calculation method of pile foundation spiral buried pipe under condition of underground water seepage |
CN106354984B (en) * | 2016-10-21 | 2020-05-19 | 山东中瑞新能源科技有限公司 | Temperature response calculation method of pile foundation spiral buried pipe under underground water seepage condition |
CN107145705A (en) * | 2017-03-29 | 2017-09-08 | 中国海洋石油总公司 | A kind of method and device for obtaining circulating temperature |
CN107391807B (en) * | 2017-06-28 | 2019-10-29 | 西安交通大学 | Plate-fin heat exchanger heat transfer flow performance value analogy method based on transient technology |
CN107391807A (en) * | 2017-06-28 | 2017-11-24 | 西安交通大学 | Plate-fin heat exchanger heat transfer flow performance value analogy method based on transient technology |
CN109948182A (en) * | 2019-01-30 | 2019-06-28 | 西安交通大学 | A kind of calculation method for mid-deep strata geothermal well well spacing |
CN109948182B (en) * | 2019-01-30 | 2020-10-27 | 西安交通大学 | Calculation method for well spacing of middle-deep geothermal well |
CN111539130A (en) * | 2020-05-29 | 2020-08-14 | 山东建筑大学 | Design and calculation method for drilling depth of geothermal heat exchanger of middle-deep buried pipe |
CN111539130B (en) * | 2020-05-29 | 2023-04-18 | 山东建筑大学 | Design and calculation method for drilling depth of geothermal heat exchanger of middle-deep buried pipe |
CN112487527A (en) * | 2020-11-25 | 2021-03-12 | 浙江工业大学 | Design method of solar ground source heat pump heat supply and air conditioning system |
CN113343444A (en) * | 2021-05-24 | 2021-09-03 | 河南中烟工业有限责任公司 | Structural design method of double-U-shaped cold and hot dual-purpose ground heat exchanger |
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