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1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefr
2、om, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243 TO PLACE A DOCU
3、MENT ORDER; (724) 776-4970 FAX: (724) 776-0790 SAE WEB ADDRESS http:/www.sae.org Copyright 1998 Society of Automotive Engineers, Inc. All rights reserved.Printed in U.S.A. SURFACE VEHICLE 400 Commonwealth Drive, Warrendale, PA 15096-0001 INFORMATION REPORT Submitted for recognition as an American Na
4、tional Standard J1498 REV. FEB1998 Issued1987-05 Revised1998-02 Superseding J1498 MAY90 Heating Value of Fuels 1.ScopeThe heating value or heat of combustion is a measure of the energy available from the fuel. The fraction or percentage of the heat of combustion that is converted to useful work is a
5、 measure of the thermal efficiency of an engine. Thus, a knowledge of the heat of combustion of the fuel is basic to the engineering of automotive engines. This SAE Information Report provides information on the standardized procedures for determining the heat of combustion of fuels that may be used
6、 for automotive engines. 2.References 2.1Applicable PublicationsThe following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest version of SAE publications shall apply. 2.1.1SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive
7、, Warrendale, PA 15096-0001. SAE J313Diesel Fuels SAE TSB 003Rules for SAE Use of SI (Metric) Units 2.1.2OTHER PUBLICATIONS 1.J. M. Sturtevant, “Calorimetry“, Chapter VII, Vol. I, Part V of “Physical Methods of Chemistry“, Edited by A. Weissberger and B. W. Rossiter, Wiley-Interscience, New York, NY
8、, 1971. 2.ASTM Methods cited throughout the text are available in the latest volume of the Annual Book of ASTM Standards as shown as follows. These volumes are available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. Method Volume D 8605.01 D 240 05.01 D 1018 05.01 D 1405 05.01
9、D 1826 05.05 D 1945 05.05 D 1946 05.05 D 2015 05.05 D 216305.01 D 2421 05.01 SAE J1498 Revised FEB1998 -2- D 2650 05.02 D 3286 05.05 D 3338 05.02 D 3588 05.05 D 3701 05.02 D 4529 05.02 D 4809 05.03 D 4868 05.03 E 380 14.02 E 711 11.04 3.F.D. Rossini, K. S. Pitzer, R. L. Arnett, R. M. Braun, and G. C
10、. Pimental, “Selected Values of Physical and Thermodynamic Properties of Hydrocarbons and Related Compounds“, pp. 445463, Carnegie Press, Carnegie Institute of Technology, Pittsburgh, PA, 1953. 4.ASTM Data Series Publication DS4B, “Physical Constants of Hydrocarbon and Non-Hydrocarbon Compounds“, AS
11、TM, West Conshohocken, PA, 1991. 5.“Reference Data for Hydrocarbons and Petro-Sulfur Compounds“, Phillips Petroleum Company Bulletin No. 521, Bartlesville, Oklahoma. 6.R. C. Wilhoit and B. J. Zwolinski, “Physical and Thermodynamic Properties of Aliphatic Alcohols“, Journal of Physical and Chemical R
12、eference Data, Vol. 2, Supplement No. 1, 1973, American Chemical Society and the American Institute of Physics. 7.E. S. Domalski, “Selected Values of Heats of Combustion and Heats of Formation of Organic Compounds Containing the Elements of C, H, N, O, P, and S“, Journal of Physical and Chemical Ref
13、erence Data, Vol. 1, No. 2, pp. 221278, 1972, American Chemical Society and the American Institute of Physics. 8.“Technical Data Book - Petroleum Refinery“, 3rd Edition, American Petroleum Institute, Washington, DC, 1977. 9.J. D. Cox and G. Pilcher, “Thermochemistry of Organic and Organometallic Com
14、pounds“, Academic Press, 1970. 3.Measurement Of Heat Of CombustionHeats of combustion can be determined to high precision by burn- ing a known amount of the sample completely in pure oxygen in a calibrated calorimeter. The heat of combus- tion is the product of the temperature rise and the total hea
15、t capacity of the calorimeter and its contents. For precision measurements, corrections are applied for energy added to initiate combustion and for the energy involved in the formation of extraneous products such as nitric acid and sulfuric acid. Calorimeters of various types have been developed to
16、obtain heats of combustion of gases, liquids, or solids to various levels of precision (Reference 1). For evaluation of fundamental thermodynamic properties, precision of calorimetric measurements of the highest order is required since the results are obtained as small differences in large quantitie
17、s. For heats of combustion of fuel mixtures, lower precisions are usually sufficient for many purposes and less sophisticated techniques are usually used. Heats of combustion or calorific values of gaseous fuels are usually measured in flame calorimeters in which the sample and oxygen react at const
18、ant pressure. Heats of combustion of solid and liquid fuels are usually measured in bomb calorimeters at constant volume. 4.Units Of MeasurementIn the SI system of measurement, the heat of combustion is expressed in joules per kilogram. For materials generally used as fuels, the heat of combustion i
19、s of such magnitude that it is customarily expressed in terms of a multiple of the basic unit, namely in megajoules per kilogram, MJ/kg. Where the molecular weight is known as in pure compounds, it is sometimes expressed in terms of megajoules per mole, MJ/mole. A large body of literature is availab
20、le - and still accumulating - in terms of other, non-SI units such as calories per gram or British Thermal Units (Btu) per pound. The following factors can be used in converting these other units to SI units as in Table 1: SAE J1498 Revised FEB1998 -3- SAE TSB 003 and ASTM E 380 list conversion fact
21、ors for units other than those included here. In any conversions, the number of digits retained should not exceed that implied by the precision of the original quantity. Many fuels are sold by volume. Heating values are, therefore, frequently expressed in terms of heat units on a volume basis. Thus,
22、 the heating values of gaseous fuels are given in terms of heat units per cubic foot or per cubic meter and those of liquid fuels are frequently given in terms of heat units per gallon or per liter. These terms can be computed to a mass basis using the density in appropriate units at the appropriate
23、 temperature and pressure. 5.Types of Heating ValuesFour types of heating values may be defined according to the assumed state of water as a combustion product (gaseous or liquid) and according to the nature of the assumed combustion process (constant volume or constant pressure). Gross (liquid wate
24、r) and net (gaseous water) heating values differ by the heat of vaporization of the water in the combustion product mixture. Constant volume and constant pressure heating values differ by the heat equivalent of the work represented by the volume change at constant pressure caused by the change in th
25、e number of moles during combustion. Numerical differences between constant volume and constant pressure combustion are small and normally neglected for fuels. Tables of heating values usually list gross and net values at constant pressure. ASTM D 4809 defines the gross heat of combustion, Qg, as fo
26、llows: “The gross heat of combustion at constant volume of a liquid or solid fuel containing only the elements carbon, hydrogen, oxygen, nitrogen, and sulfur is the quantity of heat liberated when a unit mass of the fuel is burned in oxygen in an enclosure of constant volume, the products of combust
27、ion being gaseous carbon dioxide, nitrogen, sulfur dioxide, and liquid water, with the initial temperature of the fuel and the oxygen and the final temperature of the products at 25 C.“ ASTM D 4809 also defines the net heat of combustion, Qn, as: “The net heat of combustion at constant pressure of a
28、 liquid or a solid fuel containing only the elements carbon, hydrogen, oxygen, nitrogen, and sulfur is the quantity of heat liberated when a unit mass of the fuel is burned in oxygen at a constant pressure of 0.101 MPa (1 atm), the products of combustion being carbon dioxide, nitrogen, sulfur dioxid
29、e, and water, all in the gaseous state, with the initial temperature of the fuel and the oxygen and the final temperature of the products of combustion at 25 C.“ These two types are interrelated by Equation 1: (Eq. 1) where: Qn (net, 25 C) = net heat of combustion at constant pressure, MJ/kg Qg (gro
30、ss, 25 C) = gross heat of combustion at constant volume, MJ/kg H = mass % hydrogen in sample. TABLE 1UNITS OF MEASUREMENT To Convert FromToMultiply by Calorie (International Table)Joule (J)4.186 800 British Thermal Unit (IT)Joule (J)1055.056 Calorie/GramMegajoules/kilogram (MJ/kg)0.004 186 800 Btu/p
31、oundMegajoules/kilogram (MJ/kg)0.002 326 000 Pound (Avoirdupois)Kilogram (kg)0.453 592 4 Btu/cubic foot Megajoules/cubic meter (MJ/m3) 0.037 258 95 Qn (net, 25 C) = Qg (gross, 25 C)0.2122H SAE J1498 Revised FEB1998 -4- NOTEThe percentage of hydrogen in the sample may be determined in accord with AST
32、M D 1018 or with ASTM D 3701 (IP 338). The net heat of combustion is also known as the “lower heating value, (LVH)“. It is the value customarily used in calculating thermal efficiency of engines since the exhaust gases are emitted at nearly the same pressure as that of the air and fuel supplied to t
33、he inlet system and since they contain water in the uncondensed or vapor state. 6.Standard ConditionsWhenever heats of combustion are reported, the temperature, pressure, and physical state (solid, liquid, gas) of the reactants and products should be included. By international convention, a standard
34、 state of 25C and 1 atm pressure is currently in use. It should be noted that in the change to the SI system of measurement, the standard state pressure is being changed to 1 bar, which is 100 kPa, instead of 1 at which is 101.3250 kPa. Few data are yet available at 1 bar pressure. This change will
35、have negligible effect on the practical heating value of fuels. Many data in the technical literature are given at temperatures other than the standard reference temperature of 25C. These can be converted to 25C (77F) by correcting for the difference between the total heat capacity of the products o
36、f the combustion and the total heat capacity of the reactants at constant pressure. ASTM DS 4B, p. 62 (Reference 4) provides the details of such corrections when the heat capacities are known. ASTM D 2382 provides a series of empirical correction factors that can be used for petroleum fuels when the
37、 heat capacities are unknown. Equation 2 applies to such corrections: (Eq. 2) where: A = correction factor Although heating values of gaseous fuels are usually expressed in terms of heating units per cubic foot, the amount of gas contained in a cubic foot has not been completely standardized through
38、out the gas industry. In ASTM D 1826, the standard cubic foot is regarded to be the quantity of gas that will fill one cubic foot at a standard pressure of 14.73 psia (71.92 kg/m2) and a standard temperature of 60 F (15.56 C) when in equilibrium with water. 7.Heating Values of Pure CompoundsThe heat
39、s of combustion of pure compounds, particularly hydrocarbons, have been measured with great precision because of their significance in elucidating structures and the chemical, physical, and thermodynamic properties of organic molecules. Major compilations of such data have been published (References
40、 2 to 9) showing centimeter-gram-second metric and/or U.S. inch-pound units at standard state conditions of 25 C and 1 atm pressure. 8.Heating Values of MixturesHeating values of mixtures of nonpolar liquids and gases, which do not react, are generally additive for practical purposes and can be comp
41、uted from the known amounts and heating values of each component. When any of the components are polar liquids, solids, or gases that interact with each other, the heats of combustion may no longer be additive and, therefore, should be measured calorimetrically. If water is present in the fuel as is
42、 frequently the case with such fuels as oxygenated fuels and coals, the total net heating value of the wet fuel will be lower than that of dry fuel. In this case, some of the heat of burning the fuel will be spent in evaporating the water present with the fuel. Qg (gross, 25 C) = Qg (gross, t C) + A
43、 (t C 25 C) SAE J1498 Revised FEB1998 -5- 9.Standardized Methods for Measuring Heating ValuesA variety of methods for measuring or estimating the heating values of fuels have been standardized by technical societies. The methods published by ASTM include statements of precision which are included he
44、re as guides to the usefulness of the method in proposed applications. A statement on precision, i.e., repeatability and reproducibility, provides information on the degree of mutual agreement between individual measurements while a statement on accuracy provides information on the agreement of the
45、measurements with an accepted reference value. In general, 95% of the measurements can be expected to lie within the precision limits stated in the method when conducted properly. However, readers are cautioned to examine each of the methods for full information including the range of materials incl
46、uded in the interlaboratory comparison on which the method is based. It should also be noted that the precision of the methods for computing heats of combustion from measured values of other properties such as aniline point and gravity are dependent upon the precision of these measured values rather
47、 than on the computation process. 9.1Gaseous FuelsThe heat of combustion of a gaseous fuel can be measured directly or can be calculated from the composition of the mixture and the heats of combustion of its individual constituents provided that there is no chemical reaction between the constituents
48、. ASTM D 1826 is a standardized procedure for measuring the heat of combustion of gases in the natural gas range of 900 to 1200 Btu/standard ft3 with a precision of 0.3 to 0.5%. In this procedure, the test gas is burned in a stream of air and the temperature rise of the air stream is measured. The w
49、ater is condensed to the liquid state and the gross heat of combustion is obtained. ASTM D 3588 is applicable to all common types of utility gaseous fuels for which suitable methods of analysis are available. This includes dry natural gas, reformed gas, oil gas (both high and low Btu), propane-air, carbureted water gas, and coke oven and retort coal gas. The calorific values are calculated from the molar composition and the respective ideal gas values for the components. These values must then be converted to the real gas basis by means of compressibility