CN105302984A - Modeling and simulation method for ground source heat pump set - Google Patents

Abstract

The invention discloses a modeling and simulation method for a ground source heat pump set. The method fully takes influences on operation energy consumption of the ground source heat pump set when the ground source heat pump set operates under partial load into consideration. The method comprises the steps that when a ground source heat pump mathematical model is utilized for conducting analogue simulation, it is concluded that the model can accurately reflect performance change rules of the ground source heat pump set in the operation process in a variable working condition, and in another word, when the partial load rate of the set is increased gradually, the COP of the set tends to be increased firstly and then decreased; when the side flow rate of an evaporator or the side flow rate of a condenser is increased, the COP of the set is increased, and otherwise, the COP of the set is decreased; under the refrigeration mode, when the temperature of water flowing out of the evaporator rises and the temperature of backwater at the side of the condenser is lowered, the COP of the set is increased, and otherwise, the COP of the set is decreased. The model is applied to a TRNSYS simulation platform for establishing a buried pipe ground source heat pump system, and through analogue simulation conducted on the system, it is concluded that when the ground source side adopts variable flow operation, operation energy consumption of a whole air-conditioning system can be saved.

Description

A kind of earth source heat pump unit modeling and simulating method

Technical field

The present invention relates to earth source heat pump, particularly relate to a kind of earth source heat pump unit modeling and simulating method.

Background technology

The full name of TRNSYS is TransientSystemSimulationProgram, by a instantaneous system simulator program of Univ Wisconsin-Madison USA's sun power development in laboratory, in recent years, heating ventilation air-conditioning system running optimizatin and energy-conservation in apply comparatively widely to obtain.When utilizing TRNSYS to carry out variable-flow analogue simulation to buried pipe ground-source heat pump system, find that the earth source heat pump set modules Type927 that TRNSYS provides exists some defects, and these defects impact to the accuracy of simulation result.Its defect mainly contains following 2 points;

1) unit load side outlet water temperature can not be set to definite value, is set as 7 DEG C, is set as 45 DEG C when heating as during refrigeration.Source pump is in actual moving process, as long as Building Cooling load is within the scope of its refrigeration or heating capacity, source pump load side outlet water temperature well can remain on the temperature of setting.And Type927 not only can not keep outlet temperature constant, and when unit part load ratio changes, the fluctuation of load side outlet water temperature is very large.In cooling mode, when source pump condenser side backwater water temperature is constant, condenser side flow is constant, unit part load ratio increases gradually, the analog result of Type927 as shown in Figure 1.As shown in Figure 1, when unit part load ratio is 0.25, vaporizer side outlet water temperature is-391.75 DEG C, and this is very unreasonable.

2) do not consider that source pump runs the impact on its performance at part load.Generally speaking, unit COP presents the trend of first increases and then decreases along with the increase of part load ratio.As shown in Figure 1, along with the increase gradually of part load ratio, Type927 analog result shows: when rate of load condensate is less than 0.85, unit COP changes with the change of rate of load condensate hardly, when rate of load condensate is greater than 0.85, unit COP sharply increases with the increase of rate of load condensate.Therefore, Type927 situation about running at part load and practical operation situation are not inconsistent.

In order to overcome the deficiency that Type927 occurs when source heat pump system in analog, increasing the accuracy of analogue simulation, being necessary the earth source heat pump unit modeling and simulating method studying a kind of realistic ruuning situation newly.

Summary of the invention

The object of the invention is in order to provide a kind of realistic operating condition, can be applied to earth source heat pump load side, the earth source heat pump unit modeling and simulating method of source variable-flow simulation study.

In order to reach above-mentioned purpose, the present invention adopts following technical scheme:

A kind of earth source heat pump unit modeling and simulating method, concrete steps are as follows:

Step one: the definition of parameter and variable: the variable in statistics block mold and parameter are also named respectively and identify;

Step 2: according to vaporizer side discharge M _e, vaporizer side output water temperature T _co, vaporizer side backwater water temperature T _ei, condenser side discharge M _c, condenser side backwater water temperature T _ci, set up the mathematical model of the earth source heat pump unit run under being applicable to sub-load; Thus calculate the refrigerating capacity Q of the current needs of source pump, source pump descends refrigerating capacity CAP at full capacity _max, the power input P needed for source pump, condenser side output water temperature T _cowith source pump COP value;

Step 3: develop earth source heat pump unit emulation module according to the mathematical model of step 2 on emulation platform;

Step 4: utilize the source pump emulation module that step 3 is developed on emulation platform, carry out analogue simulation.

Its intermediate is that the load of air-conditioning is in 10% to 100% interval.

Further, the calculation procedure of the power input P in described step 2 needed for source pump is as follows:

(2.1) source pump maximum cooling capacity CAP is calculated _maxwith the refrigerating capacity Q of the current needs of source pump;

(2.2) maximum cooling capacity CAP is compared _maxwith the refrigerating capacity Q of current needs, if maximum cooling capacity CAP _maxwhen being more than or equal to the refrigerating capacity Q of current needs, evaporator output water temperature is kept to be setting value, if maximum cooling capacity CAP _maxwhen being less than the refrigerating capacity Q of current needs, then after raising vaporizer side outlet water temperature, return step 2.1;

(2.3) by source pump required input power P under declared working condition ₀, power input correction factor P _r1with source pump power input correction factor P under sub-load _r2calculate the power input P needed for source pump.

Further, source pump maximum cooling capacity CAP is calculated according to formula (1) in described step (2.1) _max:

CAP _max＝f ₁(M _e，M _c，T _eo，T _ci)(1)

Described formula (1) can be rewritten as formula (2):

CAP _max＝CAP ₀·CAP _r(2)

CAP _r＝f ₂(r _me，r _mc，r _Teo，r _Tci)(3)

Wherein, CAP ₀for the refrigerating capacity of unit under declared working condition during oepration at full load, CAP _rfor the correction factor of unit refrigerating capacity under actual condition, r _mefor the ratio of the actual discharge of vaporizer side and specified discharge; r _mcfor the ratio of the actual discharge of condenser side and specified discharge; r _teothe ratio of water temperature and nominal outlet port water temperature is exported for vaporizer side is actual; r _tcifor the ratio of condenser side actual backwater water temperature and specified backwater water temperature.

Further, the refrigerating capacity Q of the current needs of current source pump is calculated in described step (2.1) according to formula (4):

Q＝CM _eΔt(4)

Wherein, Δ t is vaporizer side supply backwater temperature difference, DEG C, Q is the refrigerating capacity of the current needs of source pump, kJ/h.

Further, the power input P through type (5) needed for described source pump calculates:

P＝P ₀P _r1P _r2＝P ₀f ₆(r _me，r _mc，r _Teo，r _Tci)f ₅(PLR)(5)

Wherein, PLR is source pump part load ratio.

Further, condenser side output water temperature T is calculated according to formula (6) in described step 2 _co:

$T_{\mathrm{co}}=T_{\mathrm{ci}}+\frac{P+Q}{C{M}_c}---\left(6\right)$

Wherein, T _cifor condenser side backwater water temperature, M _cfor condenser side discharge.

Further, unit COP value is calculated according to formula (4), (5) in described step 2:

Q＝CM _eΔt(4)

P＝P ₀P _r1P _r2＝P ₀f ₆(r _me，r _mc，r _Teo，r _Tci)f ₅(PLR)(5)

$\mathrm{COP}=\frac{Q}{P}=\frac{Q}{P_0{P}_{r1}{P}_{r2}}---\left(7\right).$

Further, the correction factor through type (8) of described unit refrigerating capacity under actual condition calculates:

CAP _r＝a ₁+b ₁r _me+b ₂r _me ²+c ₁r _mc+c ₂r _mc ²+d ₁r _Teo+d ₂r _Teo ²+e ₁r _Tci+e ₂r _Tci ²+f ₁r _Teor _Tci(8)。

Further, described power input correction factor P _r1calculate with formula (9):

P _r1＝a ₂+b ₃r _me+b ₄r _me ²+c ₃r _mc+c ₄r _mc ²+d ₃r _Teo+d ₄r _Teo ²+e ₃r _Tci+e ₄r _Tci ²+f ₂r _Teor _Tci(9)；

Source pump power input correction factor P under described sub-load _r2calculate with formula (10):

P _r2＝a ₃+a ₄PLR+a ₅PLR ²(10)。

Principle of work of the present invention is: in actual conditions, when source pump gradually becomes operation at part load from oepration at full load, because total heat exchange amount reduces, the relative heat interchanging area of source pump heat interchanger increases, heat exchange efficiency improves, so the efficiency of unit also increases accordingly.Simultaneously due to the reduction of condensing temperature, the rising of evaporating temperature, the reduction of refrigerant flow, this makes the COP of source pump improve further at part load.When the part load ratio of source pump reduces further, refrigerant flow continues to reduce, and due to the too low and reason such as cause motor radiating not enough of inspiratory capacity, causes compressor efficiency significantly to reduce, thus causes unit COP significantly to decline.The unit COP calculated after considering source pump sub-load tallies with the actual situation, and has better guidance to practical application.

The invention has the beneficial effects as follows:

1) modeling and simulating method in the present invention, take into full account that source pump runs the impact on its energy consumption at part load, by checking, show that source pump COP presents the trend of first increases and then decreases with the increase gradually of part load ratio, vaporizer side outlet water temperature maintains setting value simultaneously.Demonstrate modeling and simulating method to tally with the actual situation.

2) by checking, when the part load ratio of source pump is constant, draw the change modeling relation of source pump COP with vaporizer side throughput ratio, condenser side throughput ratio, unit COP is subject to the impact of vaporizer side flow and condenser side fluctuations in discharge, no matter which effluent amount increases, unit COP all will increase, no matter which effluent amount reduces, unit COP all will reduce, and demonstrate modeling and simulating method and tally with the actual situation.

3) by checking, when the part load ratio of source pump is constant, show that unit COP increases when the rising of evaporator output water temperature, condenser side backwater water temperature reduce.On the contrary, unit COP then reduces, and demonstrates modeling and simulating method and tallies with the actual situation.

4) utilize the modeling and simulating method in the present invention, after simulation analysis, show that ground source variable-flow operation can save the operation energy consumption of whole air-conditioning system.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of Type927 analog result;

Fig. 2 is the simulation result of source pump module in the present invention.

Fig. 3 is earth source heat pump unit program flow diagram in the present invention;

Fig. 4 be in the present invention source pump COP with vaporizer side flow when condenser side throughput ratio change simulation drawing;

Fig. 5 is the simulation drawing that in the present invention, source pump COP changes with vaporizer side output water temperature and condenser side backwater water temperature;

Fig. 6 is the simulation drawing that in the present invention, source pump COP changes with part load ratio, condenser side backwater water temperature;

Fig. 7 is that in the present invention, after emulation, ground source variable-flow exports water temperature comparison diagram with ground source constant flow underground pipe;

Fig. 8 is emulation rear ground source variable-flow and ground source constant flow condensator outlet water temperature comparison diagram in the present invention;

Fig. 9 be in the present invention emulation after source pump energy consumption, land source side water pump energy consumption with the minimum running frequency change curve of variable frequency pump;

Figure 10 emulates rear ground source total energy consumption with the minimum running frequency change curve of variable frequency pump in the present invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, clear, complete description is carried out to the technical scheme in the embodiment of the present invention.

Suppose that the refrigerating capacity of source pump under different operating mode during oepration at full load is CAP _max, then CAP _maxexport water temperature with vaporizer side discharge, condenser side discharge, vaporizer side, condenser side backwater water temperature is relevant.CAP _maxcan by following function representation:

CAP _max＝f ₁(M _e，M _c，T _eo，T _ci)(1)

In formula: M _efor vaporizer side discharge, kg/h; M _cfor condenser side discharge, kg/h; T _eofor vaporizer side output water temperature, DEG C; T _cifor condenser side backwater water temperature, DEG C.

For unified dimension, formula (1) can be rewritten as following formula:

CAP _max＝CAP ₀·CAP _r(2)

CAP _r＝f ₂(r _me，r _mc，r _Teo，r _Tci)(3)

In formula: CAP ₀for the refrigerating capacity of unit under declared working condition during oepration at full load, kJ/h; CAP _rfor the correction factor of unit refrigerating capacity under actual condition; r _mefor the ratio of the actual discharge of vaporizer side and specified discharge; r _mcfor the ratio of the actual discharge of condenser side and specified discharge; r _teothe ratio of water temperature and nominal outlet port water temperature is exported for vaporizer side is actual; r _tcifor the ratio of condenser side actual backwater water temperature and specified backwater water temperature.

Work as T _eoduring for design load, source pump needs the refrigerating capacity reached, shown in (4):

Q＝CM _eΔt(4)

In formula: Q is the refrigerating capacity that source pump needs to reach, kJ/h; C is the specific heat capacity of fluid, kJ/ (kg DEG C); Δ t is vaporizer side supply backwater temperature difference, DEG C.

As Q≤CAP _maxtime, keep vaporizer side outlet water temperature to be set water temperature, as 7 DEG C; Because the refrigerating capacity of source pump is relevant with condenser side return water temperature, when the refrigeration duty of the demand of building increases to a certain degree, condenser side return water temperature will be greater than specified return water temperature.Now, refrigerating capacity during source pump oepration at full load will be less than specified refrigerating capacity, likely causes the refrigerating capacity of building needs to be greater than the refrigerating capacity of source pump oepration at full load under this kind of operating mode, i.e. Q > CAP _max.As Q > CAP _maxtime, with reference to the processing mode of Type666, namely by improving vaporizer side outlet water temperature, the refrigerating capacity of source pump is strengthened, thus meet the demand of current refrigeration capacity.

The calculating of source pump part load ratio is such as formula shown in (11):

$\mathrm{PLR}=\frac{Q}{{\mathrm{CAP}}_{\max }}---\left(11\right)$

In formula: PLR is source pump part load ratio.

Power input needed for source pump not only with M _e, M _c, T _eo, T _cirelevant, also relevant with unit part load ratio, shown in (12):

P＝f ₃(M _e，M _c，T _eo，T _ci，PLR)(12)

Also do regretional analysis for the ease of the later stage simultaneously, PLR is considered as an independent variable, that is:

P＝f ₄(M _e，M _c，T _eo，T _ci)f ₅(PLR)(13)

Equally, for ease of unified dimension, formula (13) can be rewritten as following expression:

P＝P ₀P _r1P _r2＝P ₀f ₆(r _me，r _mc，r _Teo，r _Tci)f ₅(PLR)(5)

In formula: P ₀for source pump required input power under declared working condition, kJ/h; P _r1for descending source pump power input correction factor at full capacity; P _r2for source pump power input correction factor under sub-load.

Condenser side outlet water temperature can be calculated by formula (6):

$T_{\mathrm{co}}=T_{\mathrm{ci}}+\frac{P+Q}{C{M}_c}---\left(6\right)$

In formula: T _cofor condenser side output water temperature, DEG C.

The COP of source pump can be calculated, shown in (7) by formula (4), formula (5):

$\mathrm{COP}=\frac{Q}{P}=\frac{Q}{P_0{P}_{r1}{P}_{r2}}---\left(7\right)$

With reference to DOE-2 model, CAP _r, P _r1, P _r2can be given by the following formula:

CAP _r＝a ₁+b ₁r _me+b ₂r _me ²+c ₁r _mc+c ₂r _mc ²+d ₁r _Teo+d ₂r _Teo ²+e ₁r _Tci+e ₂r _Tci ²+f ₁r _Teor _Tci(8)

P _r1＝a ₂+b ₃r _me+b ₄r _me ²+c ₃r _mc+c ₄r _mc ²+d ₃r _Teo+d ₄r _Teo ²+e ₃r _Tci+e ₄r _Tci ²+f ₂r _Teor _Tci(9)

P _r2＝a ₃+a ₄PLR+a ₅PLR ²(10)

The accuracy of this mathematical model mainly relies on accuracy and the data volume of adopted sample, solve formula (9), the sample of formula (10) comes from the sample that TRNSYS17Type927 provides, but this sample can not be directly used in and solve, the cause vaporizer side that sample provides for this reason exports water temperature and condenser side backwater water temperature is its temperature value, and formula (9) and formula (10) adopt is the ratio of actual temperature and rated temperature, therefore first to do pre-service to sample.Herein with vaporizer side outlet water temperature be 7 DEG C, condenser side backwater water temperature is 28 DEG C and does pre-service for declared working condition to this sample.Then by solving formula formula (9), formula (10) through pretreated sample.Formula (9), formula (10) are nonlinear multivariable equation, and MATLAB can be utilized to do Multiple Non Linear Regression, solve each term coefficient drawn in equation.

First regretional analysis is carried out to formula (8), following equation can be obtained by regretional analysis:

CAP _r＝0.716+0.4191r _me-0.1175r _me ²+0.0279r _mc+0.0012r _mc ²+0.1549r _Teo

(14)

+0.0002r _Teo ²-0.2929r _Tci+0.0833r _Tci ²-0.0001r _Teor _Tci

The coefficient of determination R of this regression model ²it is 9531.2 that=0.9968, F adds up value, Probability p=0 corresponding with statistic F, and due to p < 0.05, therefore this regression model is set up.

Equally, regretional analysis is carried out to formula (9), following equation can be obtained by regretional analysis:

P _r1＝0.6769+0.1128r _me-0.0436r _me ²-0.3604r _mc+0.1272r _mc ²+0.0197r _Teo

(15)

-0.0014r _Teo ²+0.2134r _Tci+0.2124r _Tci ²

The coefficient of determination R of this regression model ²it is 19883 that=0.9984, F adds up value, Probability p=0 corresponding with statistic F, and due to p < 0.05, therefore this regression model is set up.

For formula (10), because Type927 does not consider the impact of part load ratio on its performance, so its sample provided is without the correction factor of source pump power input under sub-load.To this, use for reference the sample that provides of Type666 herein to solve formula (10).By fitting of a polynomial, obtain following equation:

P _r2＝0.2726-0.08413PLR+0.8102PLR ²(16)

The coefficient of determination R of this regression model ²=0.9991, visible fitting effect is better.

For cooling in summer operating mode, the specified refrigerating capacity of earth source heat pump unit of certain model known is 1576800kJ/h, specified COP is 5, the specified discharge of vaporizer side is 75265kg/h, the specified discharge of condenser side is 88738kg/h, the specified output water temperature of vaporizer side is 7 DEG C, and the specified backwater water temperature of condenser side is 28 DEG C.Above initial value is substituted into source pump mathematical model and carries out analog computation.When the specified output water temperature of vaporizer side and the specified backwater water temperature of condenser side remain unchanged, unit keep oepration at full load time, when condenser side throughput ratio changing pattern graphoid is as shown in Figure 4 for unit COP and vaporizer side flow.

As shown in Figure 4, unit COP is subject to the impact of vaporizer side flow and condenser side fluctuations in discharge, no matter which effluent amount increases, unit COP all will increase, and no matter which effluent amount reduces, and unit COP all will reduce.Be directly proportional this is because the evaporator water side coefficient of heat transfer and the Water in Condenser side coefficient of heat transfer are similar to 0.8 power of rate of flow of fluid.When water effluent speed reduces, evaporator water side, the heat exchange of Water in Condenser side are weakened, thus cause unit COP to decline.Visible, the result of calculation of this source pump mathematical model therewith rule conforms to.

When evaporator, condenser keep specified discharge, during source pump maintenance oepration at full load, source pump COP with vaporizer side output water temperature, condenser side backwater water temperature changing pattern graphoid as shown in Figure 5.

When the rising of evaporator output water temperature, condenser side backwater water temperature reduce, unit COP increases.On the contrary, unit COP then reduces.This is because when evaporator outlet water temperature raises, the evaporating temperature of evaporator can increase to some extent, when condenser side backwater water temperature reduces, the condensing temperature of condenser can decrease, this makes under identical refrigerating capacity, and the acting of compressor reduces, thus improves the COP of unit.Visible, the result of calculation of this source pump mathematical model also therewith rule conform to.

Can also see from Fig. 6, when condenser side return water temperature raises, unit COP is on a declining curve, but the affecting laws of unit part load ratio to COP does not change, and this conforms to actual.Visible, this model can the Changing Pattern of correct response source pump run time behaviour at part load.

From above content, the modeling and simulating method in the present invention can Changing Pattern under various operating mode, may be used for simulating the impact of different operating mode on unit performance and operation energy consumption.

In TRNSYS, adopt method of the present invention to emulate, so when developing this module, first will design the interface of data transmission, and carrying out data transmission to facilitate with other modules.For this reason, the input interface of this module can be made up of following parameter, that is: vaporizer side backwater water temperature T _ei, evaporator side inlet discharge M _ei, condenser side backwater water temperature T _ci, condenser side inlet water flow M _ci.Its output interface can be made up of following parameter, that is: vaporizer side output water temperature T _eo, vaporizer side outlet stream amount M _eo, condenser side output water temperature T _co, condenser side outlet stream amount M _co, unit operation power P, unit COP, the refrigerating capacity Q that unit provides, unit part load ratio PLR, herein, vaporizer side outlet stream amount is equal with evaporator side inlet discharge, i.e. M _ei=M _eo=M _e; Condenser side outlet stream amount is equal with condenser side inlet water flow, i.e. M _ci=M _co=M _c.For the ease of defining the performance of this source pump on TRNSYS emulation platform, also need to arrange initial parameter, its initial parameter can be made up of following parameter, that is: the specified refrigerating capacity CAP of unit ₀, the specified COP of unit, the specified discharge M of vaporizer side _e0, the specified discharge M of condenser side _c0, the specified output water temperature T of vaporizer side _eo0, the specified backwater water temperature T of condenser side _ci0, and formula (8, (9) and (10) every fitting coefficient.Using input parameter and initial parameter as known quantity, output parameter, as variable to be solved, is that theoretical foundation works out C programmer by the earth source heat pump unit mathematical model of upper foundation.

In order to ensure that security of system is run efficiently, the variable frequency range of reply variable frequency pump limits, and determines its minimum running frequency.Minimum running frequency can consider that the factor of following two aspects sets:

1) variable frequency pump minimum delivery flow should be not less than the minimum flow required by source pump safe operation, and in unit evaporator and condenser, fluctuations in discharge scope generally can be 30% ~ 130% of design discharge.

2) variable frequency pump minimum delivery flow should be able to ensure that the fluidised form in underground pipe is turbulent flow, i.e. reynolds number Re > 2300, and its computing formula is such as formula shown in (17):

$\mathrm{Re}=\frac{\mathrm{du}}{v}---\left(17\right)$

In formula: d is underground pipe internal diameter, m; U is velocity in pipes, m/s; V kinematic viscosity, m ²/ s.

Through type (17) can calculate the minimum flow velocity that fluidised form in holding tube is turbulent flow, and then calculates the minimum delivery rate of variable frequency pump.

The minimum delivery rate of variable frequency pump chooses the maximal value by above 2 minimum flows calculated, and by calculating, the minimum running frequency of variable frequency pump must not be less than 22Hz herein.

When local source supply backwater temperature difference is set as that 5 DEG C and the minimum running frequency of variable frequency pump are 22Hz, when underground pipe outlet water temperature is run with ground source constant flow underground pipe export water temperature more as shown in Figure 7, condensator outlet water temperature with source constant flow run time outlet temperature more as shown in Figure 8.

Visible, during local source employing variable-flow operation, underground pipe outlet water temperature decreases, and in whole refrigeration season, underground pipe outlet water temperature comparatively constant flow runs average reduction by 0.92 DEG C.When this is mainly because of local source employing variable-flow operation, ground source rate of flow of fluid reduces, but in underground pipe, fluid flow state is still turbulent flow, and fluid is elongated by the time of ground heat exchanger, this makes the heat exchange of fluid and soil more abundant, and then causes the outlet water temperature of underground pipe to reduce.Simultaneously during local source employing variable-flow operation, condensator outlet water temperature is high when comparatively source adopts constant flow to run, and in whole refrigeration season, on average exceeds 1.42 DEG C.This is because reduced by the flow of condenser, caused by the condensing temperature rising of condenser.

When soil initial temperature be 16 DEG C, source adopt variable-flow operation time, after the refrigeration season, soil medial temperature is 18.91 DEG C.When local source adopts constant flow to run, after the refrigeration season, soil medial temperature is 18.89 DEG C.Visible, after the refrigeration season, ground source variable-flow operation comparatively source constant flow operation soil medial temperature increases, but improve only 0.02 DEG C.When this is due to local source employing variable-flow operation, although underground pipe outlet water temperature reduces, because the flow by condenser reduces, condenser side heat exchange efficiency is declined to some extent and condensing temperature rising, unit performance still declines to some extent.Because unit performance reduces, cause its heat to ground heat exchanger release to increase to some extent, thus soil medial temperature is increased to some extent.

Source pump energy consumption, land source side water pump energy consumption, source total energy consumption (units consumption add ground land source side water pump energy consumption) with the change curve of the minimum running frequency of variable frequency pump as shown in Fig. 9,10.From Fig. 9, Figure 10, when the minimum running frequency of variable frequency pump increases gradually, because the variable frequency range of variable frequency pump narrows, the overall conveying water yield increases gradually, the operation energy consumption of variable frequency pump is increased gradually, because the conveying water yield of variable frequency pump increases gradually, the COP of source pump is increased, and then its operation energy consumption reduce gradually.When the minimum running frequency of variable frequency pump is less than 30Hz, the change of ground source total operation energy consumption is less, and when the minimum running frequency of variable frequency pump is greater than 30Hz, source total operation energy consumption in ground then increases rapidly.

Local source supply backwater temperature difference is set as 5 DEG C, variable frequency pump minimum running frequency is when being set as 22Hz, its every energy consumption with source constant flow run time every energy consumption more as shown in table 1.When ground source constant flow runs, water pump operation power is 10.6kW.

Table 1 is that ground source constant flow runs and ground source variable-flow operation energy consumption comparison sheet

As seen from the above table, although ground source variable-flow operation makes the operation energy consumption of source pump increase to some extent, the operation energy consumption of ground land source side water pump then greatly reduces, and province's electricity of water pump is greater than the power consumption of source pump increase, finally make source total operation energy consumption in ground less, fractional energy savings is 6.47%.

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (9)

1. an earth source heat pump unit modeling and simulating method, is characterized in that, concrete steps are as follows:

Step one: the definition of parameter and variable: the variable in statistics block mold and parameter are also named respectively and identify;

Step 2: according to vaporizer side discharge M _e, vaporizer side output water temperature T _eo, vaporizer side backwater water temperature T _ei, condenser side discharge M _c, condenser side backwater water temperature T _ci, set up the mathematical model of the earth source heat pump unit run under being applicable to sub-load; Thus calculate the refrigerating capacity Q of the current needs of source pump, source pump descends refrigerating capacity CAP at full capacity _max, the power input P needed for source pump, condenser side output water temperature T _cowith source pump COP value;

Step 3: develop earth source heat pump unit emulation module according to the mathematical model of step 2 on emulation platform;

Step 4: the earth source heat pump unit emulation module utilizing step 3 to develop on emulation platform, carries out analogue simulation.

2. a kind of earth source heat pump unit modeling and simulating method as claimed in claim 1, it is characterized in that, the calculation procedure of the power input P in described step 2 needed for source pump is as follows:

(2.1) source pump maximum cooling capacity CAP is calculated _maxwith the refrigerating capacity Q of the current needs of source pump;

(2.2) maximum cooling capacity CAP is compared _maxwith the refrigerating capacity Q of current needs, if maximum cooling capacity CAP _maxwhen being more than or equal to the refrigerating capacity Q of current needs, evaporator output water temperature is kept to be setting value, if maximum cooling capacity CAP _maxwhen being less than the refrigerating capacity Q of current needs, then after raising vaporizer side outlet water temperature, return step 2.1;

(2.3) by source pump required input power P under declared working condition ₀, power input correction factor P _r1with source pump power input correction factor P under sub-load _r2calculate the power input P needed for source pump.

3. a kind of earth source heat pump unit modeling and simulating method as claimed in claim 2, is characterized in that, calculates source pump maximum cooling capacity CAP in described step (2.1) according to formula (1) _max:

CAP _max＝f ₁(M _e，M _c，T _eo，T _ci)(1)

Described formula (1) can be rewritten as formula (2):

CAP _max＝CAP ₀·CAP _r(2)

CAP _r＝f ₂(r _me，r _mc，r _Teo，r _Tci)(3)

Wherein, CAP ₀for the refrigerating capacity of unit under declared working condition during oepration at full load, CAP _rfor the correction factor of unit refrigerating capacity under actual condition.

4. a kind of earth source heat pump unit modeling and simulating method as claimed in claim 2, is characterized in that, calculates the refrigerating capacity Q of the current needs of source pump in described step (2.1) according to formula (4):

Q＝CM _eΔt(4)

Wherein, Δ t is vaporizer side supply backwater temperature difference, DEG C, Q is the refrigerating capacity of the current needs of source pump, kJ/h.

5. a kind of earth source heat pump unit modeling and simulating method as claimed in claim 1, is characterized in that, the power input P through type (5) needed for described source pump calculates:

P＝P ₀P _r1P _r2＝P ₀f ₆(r _me，r _mc，r _Teo，r _Tci)f ₅(PLR)(5)

Wherein, r _mefor the ratio of the actual discharge of vaporizer side and specified discharge; r _mcfor the ratio of the actual discharge of condenser side and specified discharge; r _teothe ratio of water temperature and nominal outlet port water temperature is exported for vaporizer side is actual; r _tcifor the ratio of condenser side actual backwater water temperature and specified backwater water temperature, PLR is source pump part load ratio.

6. a kind of earth source heat pump unit modeling and simulating method as claimed in claim 1, is characterized in that, calculates condenser side water delivering orifice water temperature T in described step 2 according to formula (8) _co:

$T_{\mathrm{co}}=T_{\mathrm{ci}}+\frac{P+Q}{{\mathrm{CM}}_c}---\left(6\right)$

Wherein, T _cifor condenser side backwater water temperature, M _cfor condenser side discharge.

7. a kind of earth source heat pump unit modeling and simulating method as claimed in claim 1, is characterized in that, calculates unit COP value in described step 2 according to formula (4), (5):

Q＝CM _eΔt(4)

P＝P ₀P _r1P _r2＝P ₀f ₆(r _me，r _mc，r _Teo，r _Tci)f ₅(PLR)(5)

$\mathrm{COP}=\frac{Q}{P}=\frac{Q}{P_0{P}_{r1}{P}_{r2}}---\left(7\right).$

8. a kind of earth source heat pump unit modeling and simulating method as claimed in claim 3, is characterized in that, the correction factor through type (8) of described unit refrigerating capacity under actual condition calculates:

CAP _r＝a ₁+b ₁r _me+b ₂r _me ²+c ₁r _mc+c ₂r _mc ²+d ₁r _Teo+d ₂r _Teo ²+e ₁r _Tci+e ₂r _Tci ²+f ₁r _Teor _Tci(8)。

9. a kind of earth source heat pump unit modeling and simulating method as described in claim 5 or 7, is characterized in that,

Described power input correction factor P _r1calculate with formula (9):

P _r1＝a ₂+b ₃r _me+b ₄r _me ²+c ₃r _mc+c ₄r _mc ²+d ₃r _Teo+d ₄r _Teo ²+e ₃r _Tci+e ₄r _Tci ²+f ₂r _Teor _Tci(9)；

Source pump power input correction factor P under described sub-load _r2calculate with formula (10):

P _r2＝a ₃+a ₄PLR+a ₅PLR ²(10)。