1、Designation: D7668 12Standard Test Method forDetermination of Derived Cetane Number (DCN) of DieselFuel OilsIgnition Delay and Combustion Delay Using aConstant Volume Combustion Chamber Method1This standard is issued under the fixed designation D7668; the number immediately following the designation
2、 indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the quantita
3、tive determinationof the derived cetane number of conventional diesel fuel oils,diesel fuel oils containing cetane number improver additives,and is applicable to products typical of Specification D975,Grades No.1-D and 2-D regular, low and ultra-low-sulfurdiesel fuel oils, European standard EN590, a
4、nd Canadianstandards CAN/CGSB-3.517 and CAN/CGSB3.6. The testmethod may be applied to the quantitative determination of thederived cetane number of blends of fuel oils containingbiodiesel material (for example, Specification D975, biodiesel,and diesel fuel oil blending components.1.2 This test metho
5、d utilizes a constant volume combustionchamber with direct fuel injection into heated, compressedsynthetic air. A dynamic pressure wave is produced from thecombustion of the sample. An equation converts the ignitiondelay and the combustion delay determined from the dynamicpressure curve to a derived
6、 cetane number (DCN).1.3 This test method covers the ignition delay ranging from2.8 to 6.5 ms and combustion delay ranging from 5.5 to 120 ms(30.0 to 65.0 DCN). However, the precision stated only coversthe range of DCN from 35 to 60.1.4 The values stated in SI units are to be regarded asstandard. No
7、 other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bili
8、ty of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D613 Test Method for Cetane Number of Diesel Fuel OilD975 Specification for Diesel Fuel OilsD1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology
9、 Relating to Petroleum, PetroleumProducts, and LubricantsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD5854 Practice for Mixing and Handling of Liquid Samplesof Petroleum and Petroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Te
10、chniques to Evaluate AnalyticalMeasurement System PerformanceD6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsD6708 Practice for Statistical Assessment and Improvementof Expected Agreement Between Two Test Methods thatPurport to M
11、easure the Same Property of a MaterialE456 Terminology Relating to Quality and Statistics2.2 EN Standards:3EN590 Automotive FuelsDieselRequirements and TestMethods2.3 Energy Institute Standards:4IP41 Ignition Quality of Diesel FuelsCetane Engine TestMethod1This test method is under the jurisdiction
12、of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.01.0C on Test Equipment, Procedures, and Instrumentation.Current edition approved Sept. 1, 2012. Published November 2012. Originallyapproved in 2010. Last previous edition approved in 2010 a
13、s D766810. DOI:10.1520/D766810.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from European Commi
14、ttee for Standardization. Central Secretariat:rue de Stassart, 36,B-1050 Brussels, Belgium.4Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www.energyinst.org.uk.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr
15、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.4 Canadian Standards:5CAN/CGSB-3.517 Regular Sulphur Diesel FuelSpecificationCAN/CGSB 3.6 Automotive Low-Sulphur Diesel FuelSpecification2.5 DIN Standards:6DIN 73372 Einspritzdsen Grsse T und U3. Terminology3.1 Definitions
16、:3.1.1 accepted reference value (ARV), na value that servesas an agreed-upon reference for comparison and that is derivedas (1) a theoretical or established value, based on scientificprinciples, (2) an assigned value, based on experimental workof some national or international organization, such as
17、the U.S.National Institute of Standards and Technology (NIST), or (3)a consensus value, based on collaborative experimental workunder the auspices of a scientific or engineering group. E4563.1.1.1 DiscussionIn the context of this method, acceptedreference value is understood to apply to the ignition
18、 delay andthe combustion delay of specific reference materials deter-mined under reproducibility conditions by collaborative ex-perimental work.3.1.2 cetane number, na measure of the ignition perfor-mance of a diesel fuel oil obtained by comparing it to referencefuels in a standardized engine test.
19、D41753.1.2.1 DiscussionIn the context of this test method,cetane number is that defined by Test Method D613/IP41.3.1.3 check standard, nin QC testing, a material having anaccepted reference value used to determine the accuracy of ameasurement system.3.1.3.1 DiscussionIn the context of this test meth
20、od,check standard refers to the calibration reference material.3.1.4 quality control (QC) sample, nfor use in qualityassurance programs to determine and monitor the precision andstability of a measurement system, a stable and homogeneousmaterial having physical or chemical properties, or both,simila
21、r to those of typical samples tested by the analyticalmeasurement system. The material is properly stored to ensuresample integrity, and is available in sufficient quantity forrepeated, long term testing. D62993.2 Definitions of Terms Specific to This Standard:3.2.1 calibration reference material, n
22、a pure chemical ora specified mixture of pure chemicals having an assignedignition delay accepted reference value and an assigned com-bustion delay accepted reference value.3.2.2 chamber wall temperature, ntemperature, in C, ofthe combustion chamber wall.3.2.3 charge air, ncompressed synthetic air a
23、t a specifiedpressure introduced into the combustion chamber at the begin-ning of each test cycle.3.2.4 combustion analyzer, nan integrated compressionignition apparatus to measure the ignition and combustioncharacteristics of diesel fuel oil.3.2.5 combustion delay (CD), nthat period of time, inmill
24、iseconds (ms), between the start of fuel injection andmid-point of the combustion pressure curve.3.2.5.1 DiscussionIn the context of this test method, thestart of fuel injection is interpreted as the rise in the electronicsignal that opens the injector and the combustion pressurecurve mid-point is i
25、nterpreted as the part of the pressure curvemidway between the chamber static pressure and the maximumpressure generated during the combustion cycle, as measuredby a pressure sensor in the combustion chamber. The combus-tion delay CD measures the time between the injection of thesample and phase of
26、combustion controlled by the diffusivemixing of the air and fuel.3.2.6 derived cetane number (DCN), na number calcu-lated using a conversion equation to determine a cetanenumber.3.2.6.1 DiscussionThe conversion equation relates a mea-sured ignition delay or ignition delay and combustion delayfrom a
27、combustion analyzer, to a cetane number.3.2.7 ignition delay (ID), nthat period of time, in milli-seconds (ms), between the start of fuel injection and the start ofcombustion as determined using the specific combustion ana-lyzer applicable for this test method.3.2.7.1 DiscussionIn the context of thi
28、s test method, startof fuel injection is interpreted as the rise in the electronic signalthat opens the injector; combustion is interpreted as the part ofthe pressure curve generated during the combustion cycle whensignificant (+0.02 MPa above the chamber static pressure) andsustained increase in ra
29、te-of-change in pressure, as measuredby a pressure sensor in the combustion chamber.3.2.8 injection period, nthe period of time, in microsec-onds (s), that the fuel injector nozzle is open as determined bythe length of the electronic signal, in microseconds, that opensthe injector.3.2.9 operation pe
30、riod, nthe time, not to exceed 12 h,between successive calibration or QC testing, or both, of thecombustion analyzer by a single operator.3.3 Abbreviations:3.3.1 ARVaccepted reference value3.3.2 CDcombustion delay3.3.3 CNcetane number3.3.4 DCNderived cetane number3.3.5 IDignition delay3.3.6 QCqualit
31、y control4. Summary of Test Method4.1 A small specimen of sample is injected into a heated,temperature-controlled, constant volume chamber, which haspreviously been charged with compressed air of a specifiedquality. Each injection produces a compression ignition com-bustion cycle detected using a pr
32、essure sensor. The ignitiondelay and combustion delay are measured from the rise of theelectronic signal that activates the injector solenoid to two5Available from the Canadian General Standards Board, Sales Centre, Gatineau,Canada, K1A1G6. www.ongc-cgsb.ca.6Available from Beuth Verlag GmbH (DIN- DI
33、N Deutsches Institut furNormung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http:/www.en.din.de.D7668 122specific points along the combustion pressure wave producedby the combustion cycle. A complete sequence comprises 5preliminary injection cycles and 15 subsequent injection cyclesused for
34、the sample analysis. The ID and CD measurements forthe last 15 injection cycles are statistically reviewed and theoutlying IDs and CDs are eliminated using Peirces Crite-rion.7The remaining IDs and CDs are averaged to producethe two independent results. An equation converts the averageID result and
35、the average CD result into a DCN.5. Significance and Use5.1 The ID and CD values and the DCN value determinedby this test method provides a measure of the ignitioncharacteristics of diesel fuel oil used in compression ignitionengines.5.2 This test can be used by engine manufacturers, petro-leum refi
36、ners and marketers, and in commerce as a specifica-tion aid to relate or match fuels and engines.5.3 The relationship of diesel fuel oil DCN determinationsto the performance of full-scale, variable-speed, variable-loaddiesel engines is not completely understood.5.4 This test can be applied to non-co
37、nventional dieselfuels.5.5 This test determines ignition characteristics and requiresa sample of approximately 370 mL and a test time ofapproximately 30 min using a fit-for-use instrument.6. Interferences6.1 WarningMinimize exposure of sample fuels, calibra-tion reference materials, QC samples, and
38、check standards tosunlight or fluorescent lamp UV emissions to minimize in-duced chemical reactions that can affect the delay measure-ments.86.1.1 Exposure of these fuels and materials to UV wave-lengths shorter than 550 nm for a short period of time cansignificantly affect ignition delay measuremen
39、ts.NOTE 1The formation of peroxide and radicals can affect ignitiondelay measurement. These formations are minimized when the sample ormaterial is stored in the dark in a cold room at a temperature of less than10C and covered by a blanket of nitrogen.7. Apparatus7.1 GeneralThis test method uses an i
40、ntegrated automatedanalytical measurement system9comprised of:7.1.1 Combustion ChamberA cylindrical chamber havinga volume of 0.473 6 005 L, with external heating elements,heat shield, and electrically actuated intake and exhaust valves.There is an opening at one end of the chamber to accommodateins
41、ertion of the fuel injection nozzle assembly and there areopenings at the other end of the chamber to insert air, removeexhaust, and attach a pressure sensor.7.1.2 Fuel Injection SystemA high pressure sample, gen-erated using a hydraulic pump and pressure multiplier, isdelivered to a commercial elec
42、tronic diesel fuel injector. Asample reservoir supplies the pressure multiplier with sampleto ensure proper and repeatable injection of calibration, QCmaterial, and test specimens into the combustion chamber. Thesystem includes:7.1.2.1 Fuel Sample ReservoirA metal reservoir having anominal volume of
43、 200 mL.7.1.2.2 Hydraulic PumpCapable of producing fuel pres-sures up to 19 MPa.7.1.2.3 Pressure Multiplier10:1 ratio.7.1.2.4 Fuel InjectorAsolenoid-based common rail dieselfuel injector from Bosch with the part number 0445110181(Annex A6).7.1.2.5 Safety Burst DiskRelieves the high pressure if thesa
44、mple pressure exceeds 180 MPa.The burst disk is attached tothe high pressure sample system manifold block opposite theinjector.7.1.2.6 Flush ValveHigh pressure air actuated valve usedto exchange samples.7.1.3 Coolant SystemA closed loop circulating coolantsystem to control the temperature of the com
45、bustion injectornozzle and dynamic pressure sensor. The system includes anauxiliary heat exchanger with built-in circulating pump andflow control valves.7.1.4 Instrument SensorsSensors used to measure andeither indicate the value of a variable or transmit the conditionfor control or data acquisition
46、 purposes such as:7.1.4.1 Combustion Chamber Static Pressure SensorAcalibrated sensor installed to correct the temperature offset ofdynamic pressure sensor.7.1.4.2 Combustion Chamber Dynamic Pressure SensorAcalibrated sensor installed to measure the pressure within thecombustion chamber.7.1.4.3 Samp
47、le Pressure SensorA calibrated sensor in-stalled to measure the pressure of the sample injected into thecombustion chamber.7.1.4.4 Nitrogen Pressure SensorA sensor installed tomeasure the inlet pressure from the nitrogen regulator.7.1.4.5 Combustion Chamber Inner Wall TemperatureSensorType K thermoc
48、ouple with a stainless steel sheath.7.1.4.6 Injector Nozzle Cooling Jacket TemperatureSensorType K thermocouple with stainless steel sheath,inserted in the injector nozzle coolant passage.7.1.5 Computerized Control, Data Acquisition, Data Analy-sis and Reporting SystemAmicroprocessor controlled syst
49、emwith a keyboard for manual entry of operating instructions, anLCD monitor for visual observation of all testing functions,and a printer for printed copy output of test results. Thecomputer-based system provides automated control of therelevant combustion analyzer and subsystem component func-tions and collects and processes all relevant signals from thetemperature and pressure sensors.7Ross, Stephen, “Peirces Criterion for the Elimination of Suspect ExperimentalData,” Journal of Engineering Technology, Fall 2003.8Sup
