1、Designation: D7668 12D7668 12aStandard 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 de
2、signation 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
3、 quantitative determination of the derived cetane number of conventional diesel fuel oils, dieselfuel oils containing cetane number improver additives, and is applicable to products typical of Specification D975, Grades No.1-Dand 2-D regular, low and ultra-low-sulfur diesel fuel oils, European stand
4、ard EN590, and Canadian standards CAN/CGSB-3.517and CAN/CGSB3.6. The test method may be applied to the quantitative determination of the derived cetane number of blends offuel oils containing biodiesel material (for example, Specification D975, biodiesel, and diesel fuel oil blending components.1.2
5、This test method utilizes a constant volume combustion chamber with direct fuel injection into heated, compressed syntheticair. A dynamic pressure wave is produced from the combustion of the sample. An equation converts the ignition delay and thecombustion delay determined from the dynamic pressure
6、curve to a derived cetane number (DCN).1.3 This test method covers the ignition delay ranging from 2.8 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 covers the range of DCN from 35 to 60.1.4 The values stated in SI units are to be reg
7、arded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and dete
8、rmine the applicability of regulatorylimitations 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 and Petroleum Prod
9、uctsD4175 Terminology Relating to Petroleum, Petroleum Products, and LubricantsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum ProductsD6299 Practice for Applying Statistical Quality Assuranc
10、e and Control Charting Techniques to Evaluate Analytical Measure-ment System PerformanceD6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and LubricantsD6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two
11、 Test Methods that Purportto Measure the Same Property of a MaterialE456 Terminology Relating to Quality and Statistics2.2 EN Standards:3EN590 Automotive FuelsDieselRequirements and Test Methods1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid
12、Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.01.0C on Test Equipment, Procedures, and Instrumentation.Current edition approved Sept. 1, 2012Nov. 1, 2012. Published November 2012November 2013. Originally approved in 2010. Last previous edition approved in 20102012as D7668
13、D7668 12.10. DOI: 10.1520/D766810.10.1520/D7668-12A.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Availab
14、le from European Committee for Standardization. Central Secretariat: rue de Stassart, 36,B-1050 Brussels, Belgium.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not
15、 be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end
16、 of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.3 Energy Institute Standards:4IP41 Ignition Quality of Diesel FuelsCetane Engine Test Method2.4 Canadian Standards:5CAN/CGSB-3.517 Regular Sulphur Diesel FuelSpecifica
17、tionCAN/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 serves as an agreed-upon reference for comparison and that is derived as(1) a theoretical or estab
18、lished value, based on scientific principles, (2) an assigned value, based on experimental work of somenational or international organization, such as the U.S. National Institute of Standards and Technology (NIST), or (3) a consensusvalue, based on collaborative experimental work under the auspices
19、of a scientific or engineering group. E4563.1.1.1 DiscussionIn the context of this method, accepted reference value is understood to apply to the ignition delay and the combustion delay ofspecific reference materials determined under reproducibility conditions by collaborative experimental work.3.1.
20、2 biodiesel, nfuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats,designated B100.3.1.3 biodiesel blend (BXX), nblend of biodiesel fuel with diesel fuel oils.3.1.3.1 DiscussionIn the abbreviation BXX, the XX represents the volume percentage of bio
21、diesel fuel in the blend.3.1.4 cetane number, na measure of the ignition performance of a diesel fuel oil obtained by comparing it to reference fuelsin a standardized engine test. D41753.1.4.1 DiscussionIn the context of this test method, cetane number is that defined by Test Method D613/IP41.3.1.5
22、check standard, nin QC testing, a material having an accepted reference value used to determine the accuracy of ameasurement system.3.1.5.1 DiscussionIn the context of this test method, check standard refers to the calibration reference material.3.1.6 quality control (QC) sample, nfor use in quality
23、 assurance programs to determine and monitor the precision and stabilityof a measurement system, a stable and homogeneous material having physical or chemical properties, or both, similar to those oftypical samples tested by the analytical measurement system. The material is properly stored to ensur
24、e sample integrity, and isavailable in sufficient quantity for repeated, long term testing. D62993.2 Definitions of Terms Specific to This Standard:3.2.1 calibration reference material, na pure chemical or a specified mixture of pure chemicals having an assigned ignitiondelay accepted reference valu
25、e and an assigned combustion delay accepted reference value.3.2.2 chamber wall temperature, ntemperature, in C, of the combustion chamber wall.3.2.3 charge air, ncompressed synthetic air at a specified pressure introduced into the combustion chamber at the beginningof each test cycle.3.2.4 combustio
26、n analyzer, nan integrated compression ignition apparatus to measure the ignition and combustioncharacteristics of diesel fuel oil.4 Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http:/www.energyinst.org.uk.5 Available from the Canadian General Standards Board, Sales
27、Centre, Gatineau, Canada, K1A1G6. www.ongc-cgsb.ca.6 Available from Beuth Verlag GmbH (DIN- DIN Deutsches Institut fur Normung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http:/www.en.din.de.D7668 12a23.2.5 combustion delay (CD), nthat period of time, in milliseconds (ms), between the start
28、of fuel injection and mid-point ofthe combustion pressure curve.3.2.5.1 DiscussionIn the context of this test method, the start of fuel injection is interpreted as the rise in the electronic signal that opens the injectorand the combustion pressure curve mid-point is interpreted as the part of the p
29、ressure curve midway between the chamber staticpressure and the maximum pressure generated during the combustion cycle, as measured by a pressure sensor in the combustionchamber. The combustion delay CD measures the time between the injection of the sample and phase of combustion controlledby the di
30、ffusive mixing of the air and fuel.3.2.6 derived cetane number (DCN), na number calculated using a conversion equation to determine a cetane number.3.2.6.1 DiscussionThe conversion equation relates a measured ignition delay or ignition delay and combustion delay from a combustion analyzer,to a cetan
31、e number.3.2.7 ignition delay (ID), nthat period of time, in milliseconds (ms), between the start of fuel injection and the start ofcombustion as determined using the specific combustion analyzer applicable for this test method.3.2.7.1 DiscussionIn the context of this test method, start of fuel inje
32、ction is interpreted as the rise in the electronic signal that opens the injector;combustion is interpreted as the part of the pressure curve generated during the combustion cycle when significant (+0.02 MPaabove the chamber static pressure) and sustained increase in rate-of-change in pressure, as m
33、easured by a pressure sensor in thecombustion chamber.3.2.8 injection period, nthe period of time, in microseconds (s), that the fuel injector nozzle is open as determined by thelength of the electronic signal, in microseconds, that opens the injector.3.2.9 operation period, nthe time, not to exceed
34、 12 h, between successive calibration or QC testing, or both, of the combustionanalyzer 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 M
35、ethod4.1 A small specimen of sample is injected into a heated, temperature-controlled, constant volume chamber, which haspreviously been charged with compressed air of a specified quality. Each injection produces a compression ignition combustioncycle detected using a pressure sensor. The ignition d
36、elay and combustion delay are measured from the rise of the electronic signalthat activates the injector solenoid to two specific points along the combustion pressure wave produced by the combustion cycle.A complete sequence comprises 5 preliminary injection cycles and 15 subsequent injection cycles
37、 used for the sample analysis.The ID and CD measurements for the last 15 injection cycles are statistically reviewed and the outlying IDs and CDs areeliminated using Peirces Criterion.7 The remaining IDs and CDs are averaged to produce the two independent results. Anequation converts the average ID
38、result and the average CD result into a DCN.5. Significance and Use5.1 The ID and CD values and the DCN value determined by this test method provides a measure of the ignition characteristicsof diesel fuel oil used in compression ignition engines.5.2 This test can be used by engine manufacturers, pe
39、troleum refiners and marketers, and in commerce as a specification aidto relate or match fuels and engines.7 Ross, Stephen, “Peirces Criterion for the Elimination of Suspect Experimental Data,” Journal of Engineering Technology, Fall 2003.D7668 12a35.3 The relationship of diesel fuel oil DCN determi
40、nations to the performance of full-scale, variable-speed, variable-load dieselengines is not completely understood.5.4 This test can be applied to non-conventional diesel fuels.5.5 This test determines ignition characteristics and requires a sample of approximately 370 mLand a test time of approxima
41、tely30 min using a fit-for-use instrument.6. Interferences6.1 WarningMinimize exposure of sample fuels, calibration reference materials, QC samples, and check standards tosunlight or fluorescent lamp UV emissions to minimize induced chemical reactions that can affect the delay measurements.86.1.1 Ex
42、posure of these fuels and materials to UV wavelengths shorter than 550 nm for a short period of time can significantlyaffect ignition delay measurements.NOTE 1The formation of peroxide and radicals can affect ignition delay measurement. These formations are minimized when the sample or materialis st
43、ored in the dark in a cold room at a temperature of less than 10C and covered by a blanket of nitrogen.7. Apparatus7.1 GeneralThis test method uses an integrated automated analytical measurement system9 comprised of:7.1.1 Combustion ChamberA cylindrical chamber having a volume of 0.473 6 005 L, with
44、 external heating elements, heatshield, and electrically actuated intake and exhaust valves.There is an opening at one end of the chamber to accommodate insertionof the fuel injection nozzle assembly and there are openings at the other end of the chamber to insert air, remove exhaust, and attacha pr
45、essure sensor.7.1.2 Fuel Injection SystemA high pressure sample, generated using a hydraulic pump and pressure multiplier, is deliveredto a commercial electronic diesel fuel injector. A sample reservoir supplies the pressure multiplier with sample to ensure properand repeatable injection of calibrat
46、ion, QC material, and test specimens into the combustion chamber. The system includes:7.1.2.1 Fuel Sample ReservoirA metal reservoir having a nominal volume of 200 mL.7.1.2.2 Hydraulic PumpCapable of producing fuel pressures up to 19 MPa.7.1.2.3 Pressure Multiplier10:1 ratio.7.1.2.4 Fuel InjectorAso
47、lenoid-based common rail diesel fuel injector from Bosch with the part number 0445110181 (AnnexA6).7.1.2.5 Safety Burst DiskRelieves the high pressure if the sample pressure exceeds 180 MPa. The burst disk is attached to thehigh pressure sample system manifold block opposite the injector.7.1.2.6 Flu
48、sh ValveHigh pressure air actuated valve used to exchange samples.7.1.3 Coolant SystemA closed loop circulating coolant system to control the temperature of the combustion injector nozzleand dynamic pressure sensor. The system includes an auxiliary heat exchanger with built-in circulating pump and f
49、low controlvalves.7.1.4 Instrument SensorsSensors used to measure and either indicate the value of a variable or transmit the condition forcontrol or data acquisition purposes such as:7.1.4.1 Combustion Chamber Static Pressure SensorAcalibrated sensor installed to correct the temperature offset of dynamicpressure sensor.7.1.4.2 Combustion Chamber Dynamic Pressure SensorA calibrated sensor installed to measure the pressure within thecombustion chamber.7.1.4.3 Sample Pressure SensorA calibrated sensor installed to m
