1、Designation: D7668 14Standard 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 biodiesel, blends of diesel fuel oilscontaining biodiesel material (for example, SpecificationsD975, D6751, and D7467), and diesel fuel oil blendingcomp
5、onents.1.2 This test method 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 dynamicp
6、ressure curve to a derived cetane number (DCN).1.3 This test method covers the ignition delay ranging from1.9 to 25 ms and combustion delay ranging from 2.5 to 160 ms(30 to 70 DCN). However, the precision stated only covers therange of DCN from 39 to 67.1.4 The values stated in SI units are to be re
7、garded asstandard. No 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 deter
8、mine the applica-bility 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 Prod
9、uctsD4175 Terminology 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 Assurancean
10、d Control Charting Techniques 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 Met
11、hods thatPurport to Measure the Same Property of a MaterialD6751 Specification for Biodiesel Fuel Blend Stock (B100)for Middle Distillate FuelsD7467 Specification for Diesel Fuel Oil, Biodiesel Blend(B6 to B20)E456 Terminology Relating to Quality and Statistics2.2 EN Standards:3EN590 Automotive Fuel
12、sDieselRequirements and TestMethods2.3 Energy Institute Standards:4IP41 Ignition Quality of Diesel FuelsCetane Engine TestMethod1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.01.
13、0C on Test Equipment, Procedures, and Instrumentation.Current edition approved Feb. 1, 2014. Published March 2014. Originallyapproved in 2010. Last previous edition approved in 2012 as D766812. DOI:10.1520/D766814.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM C
14、ustomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from European Committee for Standardization. Central Secretariat:rue de Stassart, 36,B-1050 Brussels, Belgium.4Available from Energy Ins
15、titute, 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 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.4 Canadian Standards:5CAN/CGSB-3.517 Re
16、gular Sulphur Diesel FuelSpecificationCAN/CGSB 3.6 Automotive Low-Sulphur Diesel FuelSpecification2.5 DIN Standards:6DIN 73372 Einspritzdsen Grsse T und U3. Terminology3.1 Definitions:3.1.1 accepted reference value (ARV), na value that servesas an agreed-upon reference for comparison and that is der
17、ivedas (1) a theoretical or established value, based on scientificprinciples, (2) an assigned value, based on experimental workof some national or international organization, such as the U.S.National Institute of Standards and Technology (NIST), or (3)a consensus value, based on collaborative experi
18、mental 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 delay andthe combustion delay of specific reference materials deter-mined under reproducibility conditions by collab
19、orative 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. D41753.1.2.1 DiscussionIn the context of this test method,cetane number is that defined by Test Method D613/IP41.3.1.
20、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 method,check standard refers to the calibration reference material.3.1.4 quality control (QC) sample, nfor use in quality
21、assurance programs to determine and monitor the precision andstability of a measurement system, a stable and homogeneousmaterial having physical or chemical properties, or both,similar to those of typical samples tested by the analyticalmeasurement system. The material is properly stored to ensuresa
22、mple 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, na pure chemical ora specified mixture of pure chemicals having an assignedignition delay accepted reference value and
23、 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 at a specifiedpressure introduced into the combustion chamber at the begin-ning of each test cycle.3.2.4 combustion an
24、alyzer, nan integrated compressionignition apparatus to measure the ignition and combustioncharacteristics of diesel fuel oil.3.2.5 combustion delay (CD), nthat period of time, inmilliseconds (ms), between the start of fuel injection andmid-point of the combustion pressure curve.3.2.5.1 DiscussionIn
25、 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 interpreted as the part of the pressure curvemidway between the chamber static pressure and the maximumpressure genera
26、ted 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 combustion controlled by the diffusivemixing of the air and fuel.3.2.6 derived cetane number (DCN), na number calcu-l
27、ated 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 combustion analyzer, to a cetane number.3.2.7 ignition delay (ID), nthat period of time, in milli-seconds (ms), betwe
28、en 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 this test method, startof fuel injection is interpreted as the rise in the electronic signalthat opens the injector; com
29、bustion 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 rate-of-change in pressure, as measuredby a pressure sensor in the combustion chamber.3.2.8 injection period, nthe peri
30、od 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 period, nthe time, not to exceed 12 h,between successive calibration or QC testing, or both, of thecombustion analyzer
31、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 QCquality control4. Summary of Test Method4.1 A small specimen of sample is injected into a heated,temperature-controlled, co
32、nstant volume chamber, which haspreviously been charged with compressed air of a specifiedquality. Each injection produces a compression ignition com-bustion cycle detected using a pressure sensor. The ignitiondelay and combustion delay are measured from the rise of theelectronic signal that activat
33、es 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- DIN Deutsches Institut furNormung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http:/www.en.din.de.D7668 142spec
34、ific points along the combustion pressure wave producedby the combustion cycle. A complete sequence comprises 5preliminary injection cycles and 15 subsequent injection cyclesused for the sample analysis. The ID and CD measurements forthe last 15 injection cycles are statistically reviewed and theout
35、lying 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 the average CD result into a DCN.5. Significance and Use5.1 The ID and CD values and the DCN value determinedby this
36、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 refiners and marketers, and in commerce as a specifica-tion aid to relate or match fuels and engines.5.3 The relationship
37、 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-conventional dieselfuels.5.5 This test determines ignition characteristics and requiresa sample of approximately 370 mL
38、 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 check standards tosunlight or fluorescent lamp UV emissions to minimize in-duced chemical reactions that can affect t
39、he 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 measurements.NOTE 1The formation of peroxide and radicals can affect ignitiondelay measurement. These formations are minimized
40、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 integrated automatedanalytical measurement system9comprised of:7.1.1 Combustion ChamberA cylindrical chamber havinga v
41、olume 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 accommodateinsertion of the fuel injection nozzle assembly and there areopenings at the other end of the chamber to insert air, rem
42、oveexhaust, 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 electronic diesel fuel injector. Asample reservoir supplies the pressure multiplier with sampleto ensure proper and repea
43、table 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 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
44、.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 thesample pressure exceeds 180 MPa.The burst disk is attached tothe high pressure sample system manifold block opposite th
45、einjector.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 combustion injectornozzle and dynamic pressure sensor. The system includes anauxiliary heat exchanger with built-in circ
46、ulating 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 purposes such as:7.1.4.1 Combustion Chamber Static Pressure SensorAcalibrated sensor installed to correct the temper
47、ature 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 Sample Pressure SensorA calibrated sensor in-stalled to measure the pressure of the sample injected into thecombustion ch
48、amber.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 thermocouple with a stainless steel sheath.7.1.4.6 Injector Nozzle Cooling Jacket TemperatureSensorType K thermocouple with
49、stainless steel sheath,inserted in the injector nozzle coolant passage.7.1.5 Computerized Control, Data Acquisition, Data Analy-sis and Reporting SystemAmicroprocessor controlled systemwith 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 s
