CN109654755A - A kind of solar heat collector settling time test method - Google Patents
A kind of solar heat collector settling time test method Download PDFInfo
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- CN109654755A CN109654755A CN201811338456.3A CN201811338456A CN109654755A CN 109654755 A CN109654755 A CN 109654755A CN 201811338456 A CN201811338456 A CN 201811338456A CN 109654755 A CN109654755 A CN 109654755A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
Abstract
A kind of solar heat collector settling time test method of disclosure of the invention is that require to adjust heat collector inlet temperature in order to solve the prior art in test with ambient temperature equal or need prior to know heat collector parameter, it is not able to satisfy application requirement under certain environment and designs.Disclosed a kind of solar thermal collector settling time test method, which is characterized in that it is identical as ambient temperature that adjusting solar heat collector inlet temperature is not needed when test；Heat collector exit fluid temperature is denoted as when test starts, heat collector exit fluid temperature is denoted as after reaching stable state；Record fromStart, namelyTo expression formula
Description
Technical field
The present invention relates to a kind of settling time test methods, when more particularly to a kind of solar heat collector transient process
Between test method.
Technical background
The settling time reaction of heat collector is dynamic characteristic of the heat collector to transition input response, in steady state test
In method, it can estimate that the time needed for heat collector reaches stable state or quasi-steady state is long according to the size of heat collector settling time value
It is short, as solar heat collector is using more and more extensive, heat collector settling time as solar heat collector hot property most
One of important performance indexes.
At present include heat collector settling time test method sum up available ASHRAE93-2010,
ISO9806-1 is represented, and one of two methods described in method and ASHRAE93-2010 described in ISO9806-1 will
Ask test when adjust heat collector inlet temperature it is equal with ambient temperature, this requirement was so that many areas can be suitably used for
The time of test transient time is greatly reduced, for example in Beijing, the environment temperature in winter is mostly at 0 DEG C hereinafter, if heat collector
Interior working fluid is water, cannot be tested settling time according to the regulation of above-mentioned standard at this time, ASHRAE93-2010
Though another method in does not require heat collector inlet temperature equal with ambient temperature but needs previously known parameter FRUL。
Summary of the invention
In view of defect existing for above-mentioned existing test method, the purpose of the present invention is to provide a kind of new heat collector transition
Process time test method, the method do not require the adjusting heat collector inlet temperature in test equal with ambient temperature,
It does not need to know parameter F in advanceRUL, this not only reduces test condition, but also is the heat collector of water for working fluid,
Test phase of the test of settling time in many areas greatly increases.
To achieve the above object, using following test method, test device and connection type are as shown in Fig. 1 by the present invention,
Characterized by comprising the following steps:
Step S101: test can carry out under fine day outdoor conditions, steady-state process solar irradiance during the test
Variation in average value ± 50W/m2In the range of, furthermore environment temperature will be also held essentially constant dduring test；
Step S102: opening data collecting instrument, and record falls in solar irradiance on heat collector lighting surface, heat collector into,
The temperature in exit, environment temperature and the flow for flowing through heat collector working fluid；
Step S103: adjustment flows through the flow of heat collector working fluid to setting range and keeps stable, later in step
Four or step 5 in optional one；
Step S104: blocking the solar radiation fallen on heat collector with barn door, when reaching stable state, removes barn door
(defining τ=0 at this time) simultaneously continues to record tested magnitude, and until occurring stable state again, this is tested, when outlet Temperature of Working
Variation less than 0.05 DEG C/min when, i.e., it is believed that reaching stable state；
Step S105: it first allows heat collector to reach stable state under solar radiation, is then blocked and fallen on heat collector with barn door
Solar radiation (definition at this time τ=0) until occurring stable state again, reach the judgment method of stable state as previously mentioned,
I.e. when exporting the variation of Temperature of Working less than 0.05 DEG C/min, i.e., it is believed that reaching stable state；
Step S106: the settling time of heat collector is the beginning of τ=0, Ye JicongTo expression formulaValue reach the time required when 0.95.
Theoretical foundation:
The case where first considering pure accumulation of heat when fluid does not flow in a single laying of plank covering heat collector for simplicity will
Heat collector is divided into two parts: using absorber plate, internal flow and heat-barrier material as a part, and thinking that they are in same temperature
Under, with absorber plate plate temperature TPTo represent；Using glass cover-plate layer as another part, its temperature is TC, and TC< TP。
Whole (including fluid and heat-barrier material), the energy-balance equation of heat-accumulating process for absorber plate are as follows:
Wherein: S=I (τ ' α)
For deck portion, it is assumed that it does not absorb solar radiation, then its energy equation are as follows:
It is assumed that U2(Tc-Ta)=UL(Tp-Ta), TaIt remains unchanged, by this formula to time derivation, can obtain:
(1) is added with (2) two formulas, and combines above formula, can be obtained:
It is assumed that UL≈Ut=U1U2/(U1+U2), and enable the effective heat capacity (mc) of heat collectoreAre as follows:
For having the heat collector of n-layer cover board, effective heat capacity are as follows:
A in formulaiBy heat collector overall heat loss coefficient with the ratio between from the cover layer discussed to the heat loss coefficient of environment.
Assuming that the effective heat capacity (mc) of heat collectoreBorn by absorber plate, and absorber plate with as heat-transfer working medium fluid it
Between convection transfer rate it is sufficiently large, it may be considered that the mean temperature T of fluidf,mWith the temperature T of absorber platepIt is equal, at this moment collect
In the case that hot device is in delivery useful energy income, to heat collector column energy equation:
In formula: ULFor solar heat collector heat loss factor, W/ (m2·℃)；
The referred to as heat removal factor of heat collector；
The referred to as efficiency factor of heat collector.
When heat collector working condition reaches stable state, Spline smoothing occurs suddenly for solar irradiation, at this time the work shape of heat collector
State will be from a stable state to another stable state transition.
It is assumed that heat collector entrance Temperature of Working, working medium flow and ambient air temperature remain unchanged in the process, then
Fluid mean temperature T in heat collectorf,mThe rate that changes with time and heat collector outlet temperature Tf,0The rate of changing with time has as follows
Relationship:
In this way, formula (8) are substituted into formula (7), formula (7) can be converted are as follows:
Equation (9) are rearranged to obtain:
To seem equation (10) form simply, convenient when solution, we do following replacement:
Y=Tf,0-Tf,i (11)
X (τ)=S-UL(Tf,i-Ta) (12)
Then equation (10) can turn to:
This equation represents a typical first-order system, and y is the output of system, and x is the input of system, and T is time constant,It is the amplification coefficient of system.
Consider that x (τ) has a mutation in τ=0, i.e. it is another when constant value when x (τ) is from τ < 0 changes to τ > 0
One constant value is (although in the whole process can be by UL(Tf,i-Ta) regard constant as, but S has a mutation at 0 point), this equation
General solution in τ > 0 are as follows:
Cause is as τ > 0, x (τ)=x0+It is a constant, then above formula becomes:
(15) back substitution is obtained to (17):
Equation (18) are arranged to obtain:
In this way:
As τ=∞
In this way:
Settling time TsIt is that deviation reaches ± 5% between unit-step response h (t) and steady-state value h (∞), and after
No longer exceed the shortest time of this range, therefore, for this test macro, the settling time of heat collector is expression formulaFrom 0 change to 0.95 needed for time τ.
The method is not T in derivation processf,i=TaIt is assumed that only heat collector entrance temperature need to be kept in test process
Spend Tf,i, environment temperature TaAnd flow through the mass flow of heat collector working fluidIt keeps constant, without adjusting inlet temperature, makes
It is equal with environment temperature, nor previously known heat collector parameter F need to be needed as ASHRAE 93-2010RUL。
Detailed description of the invention
Fig. 1 is solar heat collector settling time measurement system diagram.
Fig. 2 Tf,0Change with time (Tfi=38 DEG C, G presses step S104).
Fig. 3 R changes with time (Tfi=38 DEG C, G presses step S104).
Fig. 4 Tf,oChange with time (Tfi=38 DEG C, G presses step S105).
Fig. 5 R3Change with time (Tfi=38 DEG C, G presses step S105).
Fig. 6 R changes with time (Tfi=Ta, G is by step S105).
Fig. 7 R changes with time (Tfi=Ta, G is by step S104).
Fig. 8 difference test method test result compares.
Specific embodiment
For the validity for verifying new method, a series of experiments is respectively carried out in winter and summer, will have been obtained using new method
Test result be compared with the test result obtained using existing method, it was demonstrated that tested using new method effective
Property.
Embodiment 1
Test was carried out in summer.Environment temperature is at 30 DEG C or so during test.
The solar heat collector settling time test method, test device and its connection type are as shown in Fig. 1.
Characterized by comprising the following steps:
Step S101: test carries out under fine day outdoor conditions, and the variation of solar irradiance is average during the test
Value ± 50W/m2In the range of, furthermore environment temperature will be also held essentially constant dduring test；
Step S102: opening data collecting instrument, and record falls in solar irradiance on heat collector lighting surface, heat collector into,
The temperature in exit, environment temperature and flow through heat collector working fluid flow；
Step S103: adjustment flows through the flow of the working fluid of heat collector to setting value (1L/min), and keeps flow
Stablize；Adjust heat collector inlet temperature Tf,iTo 38 DEG C or so, carry out respectively later step S104, step S106 and step S105,
Step S106；
Step S104: blocking the solar radiation fallen on heat collector with barn door, when reaching stable state, removes barn door
(defining τ=0 at this time) simultaneously continues to record tested magnitude, and until occurring stable state again, this is tested, when outlet Temperature of Working
Variation less than 0.05 DEG C/min when, i.e., it is believed that reaching stable state；
Step S105: it first allows heat collector to reach stable state under solar radiation, is then blocked and fallen on heat collector with barn door
Solar radiation (definition at this time τ=0) until occurring stable state again, reach the judgment method of stable state as previously mentioned,
I.e. when exporting the variation of Temperature of Working less than 0.05 DEG C/min, i.e., it is believed that reaching stable state；
Step S106: the settling time of heat collector is the beginning of τ=0, namelyTo expression formulaValue reach the time required when 0.95.
Respectively by heat collector outlet temperature Tf,0AndThe curve changed over time is plotted in Fig. 2~5.
By Fig. 3 and Fig. 5 it is found that in this example, showing that the settling time of heat collector is 160s and 148s respectively.
Embodiment 2
Test was carried out in winter.Environment temperature is at 3 DEG C or so during test.
The solar heat collector settling time test method, test device and its connection type are as shown in Fig. 1.
Characterized by comprising the following steps:
Step S101: test can be carried out outside fine day room, during the test the variation of solar irradiance average value ±
50W/m2In the range of, furthermore environment temperature will be also held essentially constant dduring test；
Step S102: opening data collecting instrument, and record falls in solar irradiance on heat collector lighting surface, heat collector into,
The temperature in exit, environment temperature；
Step S103: adjustment flows through the flow of the working fluid of heat collector to setting value (1.04L/min), and keeps flow
Stablize；Adjust heat collector inlet temperature Tf,iIt is identical as environment temperature, carry out step S104, step S106 and step respectively later
S105, step S106；
Step S104: blocking the solar radiation fallen on heat collector with barn door, when reaching stable state, removes barn door
(defining τ=0 at this time) simultaneously continues to record tested magnitude, and until occurring stable state again, this is tested, when outlet Temperature of Working
Variation less than 0.05 DEG C/min when, i.e., it is believed that reaching stable state；
Step S105: it first allows heat collector to reach stable state under solar radiation, is then blocked and fallen on heat collector with barn door
Solar radiation (definition at this time τ=0) until occurring stable state again, reach the judgment method of stable state as previously mentioned,
I.e. when exporting the variation of Temperature of Working less than 0.05 DEG C/min, i.e., it is believed that reaching stable state；
Step S106: the settling time of heat collector is the beginning of τ=0, namelyTo expression formulaValue reach the time required when 0.95.
By variableIt changes with time and is plotted in Fig. 6~7, obtained time constant is 192s.
The present invention tests the data obtained result and ASHRAE93-2010 and ISO9806-1 test and comparison.
Using ASHRAE93-2010 and ISO9806-1 test method, above-mentioned two example is tested, test result
Fiducial value is shown in Fig. 8.
No matter test result shows whether heat collector inlet temperature is equal with ambient air temperature, is obtained with new method
The heat collector settling time arrived is of substantially equal, and with the transition tested with ASHRAE93-2010, ISO9806-1
Process time is also equal, therefore heat collector time settling time that new method proposed by the present invention is tested is effective
's.
Claims (1)
1. a kind of solar heat collector settling time test method, test device and connection type are as shown in Fig. 1, feature
It is, comprising the following steps:
Step S101: experimental bench is carried out shown in by specification attached drawing 1 and is built, test can carry out under fine day outdoor conditions, survey
The variation of steady-state process solar irradiance during examination is in ± 50 W/m of average value2In the range of, furthermore ring dduring test
Border temperature will be also held essentially constant；
Step S102: opening data collecting instrument, and record falls in the solar irradiance on heat collector lighting surface, heat collector import and export
The temperature at place, environment temperature and the flow for flowing through heat collector working fluid；
Step S103: adjustment flows through the flow of heat collector working fluid to setting range and keeps stable；Later in step 4 or
Optional one in step 5；
Step S104: blocking the solar radiation fallen on heat collector with barn door, when reaching stable state, removes barn door (definition
τ=0 at this time) and continue to record tested magnitude, until occurring stable state again, this is tested, when the variation of outlet Temperature of Working
When less than 0.05 DEG C/min, i.e., it is believed that reaching stable state；
Step S105: first allowing heat collector to reach stable state under solar radiation, is then blocked and is fallen on heat collector too with barn door
Sun radiation (defining τ=0 at this time) reaches the judgment method of stable state as previously mentioned, i.e., when out until occurring stable state again
When the variation of mouth Temperature of Working is less than 0.05 DEG C/min, i.e., it is believed that reaching stable state；
Step S106: the settling time of heat collector is the beginning of τ=0, namelyTo expression formulaValue reach 0.95 when required time.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2765173Y (en) * | 2005-01-18 | 2006-03-15 | 黄鸣 | Rapid measurement device for thermal characteristics of solar heat collector |
| CN1808094A (en) * | 2005-01-18 | 2006-07-26 | 黄鸣 | Apparatus and method for quick measurement of heat performance of solar heat collector |
| CN106769136A (en) * | 2016-12-09 | 2017-05-31 | 中国科学院电工研究所 | Paraboloid trough type solar heat-collector thermal efficiency dynamic measurement device and measuring method |
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2018
- 2018-11-12 CN CN201811338456.3A patent/CN109654755A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2765173Y (en) * | 2005-01-18 | 2006-03-15 | 黄鸣 | Rapid measurement device for thermal characteristics of solar heat collector |
| CN1808094A (en) * | 2005-01-18 | 2006-07-26 | 黄鸣 | Apparatus and method for quick measurement of heat performance of solar heat collector |
| CN106769136A (en) * | 2016-12-09 | 2017-05-31 | 中国科学院电工研究所 | Paraboloid trough type solar heat-collector thermal efficiency dynamic measurement device and measuring method |
Non-Patent Citations (3)
| Title |
|---|
| 侯宏娟等: "集热器时间常数测试方法研究", 《太阳能学报》 * |
| 王佩明等: "太阳集热器时间常数分析及测试讨论", 《太阳能学报》 * |
| 袁颖利: "内插式太阳能真内插式太阳能真空管空气集热器集热性能研究", 《上海交通大学硕士学位论文》 * |
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Address after: 100053 Beijing city Xicheng District Baiguang Road No. 1 building two Applicant after: State Grid comprehensive energy service group Co., Ltd Applicant after: NORTH CHINA ELECTRIC POWER University Address before: 100053 Beijing city Xicheng District Baiguang Road No. 1 building two Applicant before: State Grid Energy Conservation Service Co.,Ltd. Applicant before: NORTH CHINA ELECTRIC POWER University |
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Application publication date: 20190419 |