1、 ANSI/ASAE S423.1 MAR2014 Thermal Performance Testing of Open-Loop Solar Ambient Air Heaters with Defined Inlet and Outlet Conditions American Society of Agricultural and Biological Engineers ASABE is a professional and technical organization, of members worldwide, who are dedicated to advancement o
2、f engineering applicable to agricultural, food, and biological systems. ASABE Standards are consensus documents developed and adopted by the American Society of Agricultural and Biological Engineers to meet standardization needs within the scope of the Society; principally agricultural field equipme
3、nt, farmstead equipment, structures, soil and water resource management, turf and landscape equipment, forest engineering, food and process engineering, electric power applications, plant and animal environment, and waste management. NOTE: ASABE Standards, Engineering Practices, and Data are informa
4、tional and advisory only. Their use by anyone engaged in industry or trade is entirely voluntary. The ASABE assumes no responsibility for results attributable to the application of ASABE Standards, Engineering Practices, and Data. Conformity does not ensure compliance with applicable ordinances, law
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6、oval date. Newly developed Standards, Engineering Practices and Data approved after July of 2005 are designated as “ASABE“. Standards designated as “ANSI“ are American National Standards as are all ISO adoptions published by ASABE. Adoption as an American National Standard requires verification by A
7、NSI that the requirements for due process, consensus, and other criteria for approval have been met by ASABE. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreem
8、ent means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. CAUTION NOTICE: ASABE and ANSI standards may be revised or withdrawn at any time. Additionally, proc
9、edures of ASABE require that action be taken periodically to reaffirm, revise, or withdraw each standard. Copyright American Society of Agricultural and Biological Engineers. All rights reserved. ASABE, 2950 Niles Road, St. Joseph, Ml 49085-9659, USA, phone 269-429-0300, fax 269-429-3852, hqasabe.or
10、g ANSI/ASAE S423.1 MAR2014 Copyright American Society of Agricultural and Biological Engineers 1 ANSI/ASAE S423.1 MAR2014 Revision approved April 2014 as an American National Standard Thermal Performance Testing of Open-Looped Solar Ambient Air Heaters with Defined Inlet and Outlet Conditions Develo
11、ped by the ASAE Solar Energy Committee; approved by the ASAE Structures and Environment Division Standards Committee; adopted by ASAE December 1991; approved as an American National Standard February 1993; reaffirmed by ASAE December 1996; reaffirmed by ANSI March 1998; reaffirmed by ASAE December 2
12、001, January 2007, reaffirmed by ANSI January 2007; reaffirmed by ASABE and ANSI February 2012; revised March 2014; revision approved by ANSI April 2014. Keywords: Heaters, Solar, Testing 1 Purpose and Scope 1.1 The purpose of this Standard is to provide a method for testing the thermal efficiency o
13、f open-looped solar air heaters which are used exclusively for heating ambient air. The test data should provide a basis for computing technical performance and for comparing efficiency of collectors of different design and/or construction. Examples of use of solar ambient air heaters are preheating
14、 of ventilation air, heating make-up air for all types of environmental control systems, and heating of air to dry agricultural products without recirculation. 1.2 This test procedure simplifies the testing equipment needs, procedures and computations as compared to the currently recognized methods,
15、 for example, ANSI/ASHRAE Standard 93-2010, Method of Testing to Determine the Thermal Performance of Solar Collectors. 1.3 The scope of this Standard is restricted to collectors which have a fixed orientation and slope during the test and are used exclusively for heating ambient air with defined in
16、let and outlet conditions. 1.4 This Standard provides the method for using a 6 h continuous test consisting of twenty-four 15 min test periods. 2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cit
17、ed applies unless noted. For undated references, the latest approved edition of the referenced document (including any amendments) applies. 2.1 ANSI/ASHRAE 93-2010, Method of Testing to Determine the Thermal Performance of Solar Collectors 2.2 ASAE D271.2 APR1979 (R2010), Psychometric Data 3 Definit
18、ions 3.1 collector aperture area (Aa): The maximum projected area of the solar collector through which the solar radiation is admitted, m2(ft2). The area does not include partitions between collectors, framing and insulation. ANSI/ASAE S423.1 MAR2014 Copyright American Society of Agricultural and Bi
19、ological Engineers 2 3.2 surface Azimuth Angle (): Fixed solar collectors situated in the northern hemisphere are normally oriented due south. In this case, the surface azimuth angle is equal to zero. If the solar collector is oriented east or west of this direction then specify the solar surface az
20、imuth angle. 3.3 collector slope (): The collector slope is the angle between the plane of the collector absorber and a horizontal surface, in degrees. A common slope for fixed collectors is equal to the latitude of the collector location. 3.4 continuous data: Data taking is considered continuous if
21、 the instrument measures and records data once each minute or more frequently. 3.5 daily efficiency (d): The collected energy of the collector for the test day divided by the total solar energy incident on the gross collector area for the same test day, dimensionless. This equation is given below. (
22、)()()100kWhcollectorthebydintercepteenergysolarkWhcollectedenergyusefulactual% =d 3.6 other efficiency calculations (x): The collector efficiency is calculated for a given test period. The efficiency is the ratio of the collected energy from the collector per test period divided by the total solar e
23、nergy incident on the gross collector area for the same test period (also dimensionless). Efficiency for short time periods (such as one test period, see paragraph 3.13) shall not be used as an efficiency value unless the collector has quasi-steady state heat flow as indicated by constant efficiency
24、 ( 1%) for 4 continuous test periods. 3.7 useful energy collected (Qu): The amount of energy collected by the solar air heater per unit of time shall be computed from the specific heat of air flowing through the measuring device multiplied by the mass flow rate of air and by the temperature rise of
25、the air from entrance to exit of the collector, kW (Btu/hr). This is given in the equation below. )(, ifofpfuttCmQ = where: Qu= useful energy collected, kW (Btu/h) mf= mass flow rate of air, kg/s (lb/hr) Cp= specific heat of air, kJ/kg C (Btu/lb F) tf,o= average outlet air temperature, C (F) tf,i= a
26、verage inlet air temperature, C (F) 3.8 mass flow rate (mf): The mass flow rate of air entering (mf,i) and exiting (mf,o) the solar collector, kg/s (lb/s). This is also given in the equation below. pvAmf=where: = density of air, kg/m3(lb/ft3) v = average air velocity, m/s (ft/s) A = cross sectional
27、area, m2(ft2) Mass flow of air is estimated from measuring the air velocity and the cross sectional areas. The density is calculated from the ideal gas equation shown in section 7.1.1 and corrected for temperature and pressure and humidity ratio. ANSI/ASAE S423.1 MAR2014 Copyright American Society o
28、f Agricultural and Biological Engineers 3 3.9 gross area of a collector section (Ag,sx): If only a section of a collector is being tested, then the gross area of the section shall include a proportional share of the area of all supports and partitions of the entire collector. Thus, the ratio of aper
29、ture area to gross area shall be the same for the test section as for the entire collector. 3.10 gross collector area (Ag): The area obtained by multiplying the width by the length of the outside of the collector; thus, the gross collector area includes partitions between collector sections as well
30、as framing and insulation around all collector sections, m2(ft2). 3.11 insolation (Is): Instantaneous solar insolation or the sum of solar irradiance, both direct and diffuse, incident upon the plane of the collector as measured by a solar radiation pyranometer, W/m2(Btu/hrft2). 3.12 test day: A tes
31、t day shall be continuous and consist of twenty-four 15 min test periods (6 h). For a collector facing due south ( = 0 degrees), the time period should be from 9 am to 3 pm solar time. For collectors with other azimuth angles, 3 h each side of the time when the azimuth of the sun is the same as the
32、collector azimuth should be used. 3.13 test period: A test period has a 15 min duration. 4 Instrumentation 4.1 Barometer. The barometer accuracy shall be within 5.0 Pa (0.02 in. H2O). 4.2 Data recorders. The accuracy of data recorders shall be within 0.5% of full scale reading. 4.3 Flow measuring de
33、vice. The flow measuring device shall provide measurements for computing the mass flow rate or velocity of air with an overall accuracy of 1.5% of the measured rate or better. An orifice or nozzle is suggested but should be calibrated with a laminar flow element. 4.4 Humidity transducers. Relative h
34、umidity shall be obtained within 2.5% either by measurement or computation from measured data. 4.5 Manometer. The accuracy of the manometer for measuring pressure drop across the collector shall be within 2.5 Pa ( 0.010 in. H2O). 4.6 Pyranometer. The pyranometer shall measure the global shortwave ra
35、diation incident in the plane of the collector cover with an accuracy of 1% corrected for temperature. The pyranometer shall be mounted in the plane of the collector cover within 1 m of the collector and situated so that it will receive the same shortwave radiation as incident on the collector cover
36、 (including reflected light). 4.7 Thermocouples and thermometers. The accuracy of and precision of the temperature measuring devices shall be within the limits as follows: Instrument Accuracy* Instrument Precision* Temperature 0.5C ( 0.90F) 0.2C ( 0.36F) Temperature difference 0.1C ( 0.18F) 0.1C ( 0
37、.18F) *The ability of the instrument to indicate the true value of the measured quantity *Closeness of agreement among repeated measurements of the same physical quantity. 4.8 Thermopile. If the entrance of cold air through the solar collector is wide enough, several thermophiles may be used. A ther
38、mopile with 10 or more thermocouple junctions on each end shall be used to measure the voltage difference from entrance to exit of the collector. The accuracy of the voltage measurement difference shall be sufficient for computing the temperature rise through the collector with an accuracy and preci
39、sion of 0.1C or less. The readings must be averaged to indicate the average inlet (tf,i) and outlet (tf,o) air temperatures. ANSI/ASAE S423.1 MAR2014 Copyright American Society of Agricultural and Biological Engineers 4 4.9 Wind speed and direction. The wind speed shall be measured with an accuracy
40、of 1.0 m/s ( 1.8 mph) and wind direction shall be measured with an accuracy of 10 degrees. 5 Testing Conditions 5.1 Airflow rate. The testing rate of airflow through the collector shall be established at a constant value at least 1/2h before the beginning of the test to avoid a major transient heat
41、flow at start up. 5.2 Environmental conditions. The solar radiation and wind speed during the test should be typical of the environmental conditions expected during actual use of the collector. The average insolation during the test shall not be less than 400 W/m2. 5.3 Mass flow rate. The establishe
42、d mass flow rate of air shall not vary by more than 5% during the test. The mass flow rate shall be measured at the collector inlet and exhaust. It is suggested that the established rate of flow be set 3 to 6% higher than the desired test value. Fans tend to move a constant volume per unit time whic
43、h results in a smaller mass flow rate as the collector outlet air temperature increases. The small increase in mass flow rate at the beginning of the test should assist in maintaining the desired average mass flow rate. 6 Test Procedure 6.1 Test facility. The arrangement of test equipment and collec
44、tor is illustrated in Figure 1. The air-moving device may force air into the collector being tested; however, the mass flow rate must be measured in the inlet and exhaust. Figure 1 Test equipment and parameters to be measured 6.2 Collector test unit. The total collector, or a typical (representative
45、) section of the collector, consisting of at least 15% of the entire collector, shall be used for the test. If a typical section is used for the test, the following conditions must be met: 6.2.1 The gross area of the section shall be computed according to Section 3 Definitions, and the gross area mu
46、st be used in computing the energy incident on the collector section. 6.2.2 To prevent air leakage from adjacent sections into the test section, the flow channels adjacent to the test section must be operated at equal pressure to the test flow channel. If all flow channels are constructed alike, it
47、is sufficient for this condition to measure the pressure difference between the adjacent flow channel and the first flow channel of the test section and make adjustments in the flow rate so that the pressures are ANSI/ASAE S423.1 MAR2014 Copyright American Society of Agricultural and Biological Engi
48、neers 5 equal at the maximum pressure location; that is, at the end next to the air-moving device. If pressures are not the same, a different computational procedure must be employed. 6.3 Wind measurement. Wind velocity and wind direction shall be measured at mid collector height within a distance o
49、f 2 m from the test collector. Continuous measurement with an hourly average is preferred. Hourly measurement will be accepted. 6.4 Pressure drop. The static pressure difference between the collector entrance and exit at the test mass flow rate shall be measured during the first and final hour of the test and reported as the pressure required to produce the test mass flow rate at the respective times. 6.5 Temperature rise. The temperature rise from the entrance to the
