1、 ANSI/ASAE EP502 DEC1990 (R2012) Adjusting Forage Harvester Test Data for Varying Crop Moisture American Society of Agricultural and Biological Engineers ASABE is a professional and technical organization, of members worldwide, who are dedicated to advancement of engineering applicable to agricultur
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6、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 ANSI that the requirements for due proc
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9、 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.org ANSI/ASAE EP502 DEC1990 (R2012) Copy
10、right American Society of Agricultural and Biological Engineers 1ANSI/ASAE EP502 DEC1990 (R2012) Approved August 1992; reaffirmed February 2012 as an American National Standard Adjusting Forage Harvester Test Data for Varying Crop Moisture Developed by the ASAE Forage Harvesting and Utilization Comm
11、ittee; approved by the ASAE Power and Machinery Division Standards Committee; adopted by ASAE December 1990; approved as an American National Standard August 1992; reaffirmed by ASAE December 1995, December 1996; reaffirmed by ANSI March 1998; reaffirmed by ASAE December 2001, January 2007; reaffirm
12、ed by ANSI January 2007; reaffirmed by ASABE January 2012; reaffirmed by ANSI February 2012 Keywords: Forage, Harvester, Test procedure 1 Purpose and Scope 1.1 This Engineering Practice provides empirical equations to adjust forage harvester feed rates and specific energy measurements to a common cr
13、op moisture level of 65% wet basis. Historically, engineers and researchers have tried to compensate for the significant effect of changing moisture contents by converting test data to a dry mass basis, or by only comparing data obtained within a few moisture percentage points on a wet mass basis. T
14、he crop moisture compensation equations in this Engineering Practice significantly decrease data scatter as a function of moisture content when compared to data scatter on a wet or dry mass basis. 1.2 The equations described herein apply to precision-cut forage harvesters as defined in American Nati
15、onal Standard ANSI/ASAE S472, Terminology for Forage Harvesters and Forage Harvesting. This includes both cut and throw (no separate blower) and cut and blow type forage harvesters. The validity of the equations has not been established for semi-precision cut and random-cut forage harvesters. 2 Appl
16、ication Practices 2.1 The empirical equations in Section 3 Calculation of Results, for adjusting feed rate and specific energy for crop and moisture are applicable under the following conditions: 2.1.1 To avoid excessive error accumulation, the equations are best used for adjusting data for varying
17、moistures where the data was measured in the same field and under the same crop conditions, and the moisture content varied less than 10 percentage points wet basis. The equations can be used to adjust data from a single forage harvester or from two or more forage harvesters tested in the same field
18、 on a sideby-side basis. 2.1.2 The correction equations are valid for crop moisture contents greater than 40% wet basis and for theoretical lengths of cut, TLOC, less than 25 mm. 2.1.3 Considerable error can occur in comparing crop moisture compensated forage harvester data from different fields bec
19、ause of varying crop conditions (i.e., crop variety and maturity differences, soil and fertilization differences, etc.). A base or reference forage harvester must be used to identify feed rate and specific energy differences due to crop conditions from those due to machine design and/or settings. 2.
20、1.4 Past forage harvester field test experiences have shown that a minimum of 7 test repetitions are required to minimize data scatter for specific energy testing. At least 4 test repetitions are required to establish a maximum machine feed rate (i.e., capacity) for a given set of crop conditions an
21、d machine settings. Moisture content (see ASAE Standard S358, Moisture Measurement Forages), average feed rate in metric tons per hour, t/h, and average specific energy in kilowatt hours per metric ton, kWh/t, are to be measured for each test ANSI/ASAE EP502 DEC1990 (R2012) Copyright American Societ
22、y of Agricultural and Biological Engineers 2run. A reference forage harvester of similar design, of similar capacity, and with similar settings shall be tested in the same field on a side-by-side basis with the test forage harvester(s) to account for changing crop conditions during the test(s). Fora
23、ge harvester performance test data shall be reported per Section 5 Forage Harvester Performance Specifications, of ANSI/ASAE Standard S472, Terminology for Forage Harvesters and Forage Harvesting. 3 Calculation of Results 3.1 General information. The following empirical equations have been shown to
24、reduce feed rate and specific energy data scatter as a function of crop moisture when compared to feed rate and specific energy on a wet or dry mass basis (ASAE Paper No. 88-1553, Impact of Crop Moisture on Forage Harvesting Efficiency). These equations bring all feed rate and specific energy measur
25、ements to a common moisture level of 65% wet basis for maize (corn), grass, or lucerne (alfalfa). 3.2 Feed rate adjusted for crop and moisture. Feed rate adjusted for crop and moisture is the expected feed rate at 65% moisture (wet basis) for the forage harvester power level, excluding propulsion po
26、wer, measured at the original moisture level. It is the measured feed rate times a crop moisture adjustment factor. Fadj= F fMwhere: Fadj= feed rate adjusted for crop and moisture content, t/h F = measured feed rate, t/h (wet basis) fM= adjustment factor for crop moisture content, no units = 1 0.012
27、 (M-65), for maize (corn) = 1 0.018 (M-65), for grass, forage cereals = 1 49 (1/65 1/M), for lucerne (alfalfa) where: M = moisture content (wet basis), % 3.3 Capacity adjusted for crop and moisture. This is the maximum feed rate adjusted for crop and moisture calculated from measured data. 3.4 Speci
28、fic energy adjusted for crop and moisture. This specific energy is measured forage harvester power, excluding propulsion power, divided by feed rate adjusted for crop and moisture. It is expressed as kWh/t (wet basis). Eadj= P/Fadjwhere: Eadj= specific energy adjusted for crop and moisture content,
29、kWh/t P = measured power, kW Fadj= feed rate adjusted for crop and moisture content, t/h ANSI/ASAE EP502 DEC1990 (R2012) Copyright American Society of Agricultural and Biological Engineers 33.5 Specific energy difference adjusted for crop and moisture. This specific energy difference is the percent
30、difference between a harvesters adjusted specific energy and that of a reference harvester. It is expressed as _% more, or _% less specific energy adjusted for crop and moisture than the reference forage harvester. An analysis should be done to determine if the specific energy difference is statisti
31、cally significant. D = ()( )()machinereferenceEmachinereferenceEmachinetestEadjadjadj-100where: D = difference in specific energy adjusted for crop and moisture, % Eadj= specific energy adjusted for crop and moisture content, kWh/t Cited Standards ANSI/ASAE S472, Terminology for Forage Harvesters and Forage Harvesting ASAE S358, Moisture MeasurementForages Reference 1. Linde, G. W. and L. H. Bowen. 1988. Impact of crop moisture on forage harvesting efficiency. ASAE Paper No. 88-1553. ASAE, St. Joseph, MI 49085.
