1、Designation: D7668 14D7668 14aStandard 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 biodiesel,blends of diesel fuel oils containing biodiesel material (for example, Specifications D975, D6751, and D7467), and diesel fuel o
5、ilblending components.1.2 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
6、from the dynamic pressure curve to a derived cetane number (DCN).1.3 This test method covers the ignition delay ranging from 1.9 to 25 ms and combustion delay ranging from 2.5 to 160 ms (30to 70 DCN). However, the precision stated only covers the range of DCN from 39 to 67.1.4 The values stated in S
7、I units are to be regarded 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 heal
8、th practices and determine 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 Petrole
9、um and Petroleum ProductsD4175 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 Statist
10、ical Quality Assurance 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
11、Agreement Between Two Test Methods that Purportto 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 Statistics1 This
12、test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.01.0C on Test Equipment, Procedures, and Instrumentation.Current edition approved Feb. 1, 2014May 1, 2014. Published March 2014May 2014.
13、Originally approved in 2010. Last previous edition approved in 20122014 asD7668D7668 14.12. DOI: 10.1520/D766814.10.1520/D7668-14A.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume informat
14、ion, refer to the standards Document Summary page on the ASTM website.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 be technically possible to adequately depic
15、t 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 of this standardCopyright ASTM Internationa
16、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 EN Standards:3EN590 Automotive FuelsDieselRequirements and Test Methods2.3 Energy Institute Standards:4IP41 Ignition Quality of Diesel FuelsCetane Engine Test Method2.4 Canadian Standards:5CAN/CGSB-3.517 Regul
17、ar 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 serves as an agreed-upon reference for comparison and that is deriv
18、ed as(1) a theoretical or established 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 experi
19、mental work under the auspices 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 colla
20、borative experimental work.3.1.2 cetane number, na measure of the ignition performance of a diesel fuel oil obtained by comparing it to reference fuelsin a standardized engine test. D41753.1.2.1 DiscussionIn the context of this test method, cetane number is that defined by Test Method D613/IP41.3.1.
21、3 check standard, nin QC testing, a material having an accepted 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 quali
22、ty 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 ens
23、ure 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 va
24、lue 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 combust
25、ion analyzer, nan integrated compression ignition apparatus to measure the ignition and combustioncharacteristics of diesel fuel oil.3.2.5 combustion delay (CD), nthat period of time, in milliseconds (ms), between the start of fuel injection and mid-point ofthe combustion pressure curve.3.2.5.1 Disc
26、ussion3 Available from European Committee for Standardization. Central Secretariat: rue de Stassart, 36,B-1050 Brussels, Belgium.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 Ce
27、ntre, 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 14a2In the context of this test method, the start of fuel injection is interpreted as the rise in
28、 the electronic signal that opens the injectorand the combustion pressure curve mid-point is interpreted as the part of the pressure curve midway between the chamber staticpressure and the maximum pressure generated during the combustion cycle, as measured by a pressure sensor in the combustionchamb
29、er. The combustion delay CD measures the time between the injection of the sample and phase of combustion controlledby the diffusive 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 conve
30、rsion equation relates a measured ignition delay or ignition delay and combustion delay from a combustion analyzer,to a cetane 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
31、 combustion analyzer applicable for this test method.3.2.7.1 DiscussionIn the context of this test method, start of fuel injection 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 c
32、ycle when significant (+0.02 MPaabove the chamber static pressure) and sustained increase in rate-of-change in pressure, as measured 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
33、thelength of the electronic signal, in microseconds, that opens the injector.3.2.9 operation period, nthe time, not to exceed 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 CDcombust
34、ion 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, constant volume chamber, which haspreviously been charged with compressed air of a speci
35、fied quality. Each injection produces a compression ignition combustioncycle detected using a pressure sensor. The ignition delay 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 pro
36、duced by the combustion cycle.A complete sequence comprises 5 preliminary injection cycles and 15 subsequent injection cycles 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 C
37、riterion.7 The remaining IDs and CDs are averaged to produce the two independent results. Anequation converts the average ID 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
38、 characteristicsof diesel fuel oil used in compression ignition engines.5.2 This test can be used by engine manufacturers, petroleum refiners and marketers, and in commerce as a specification aidto relate or match fuels and engines.5.3 The relationship of diesel fuel oil DCN determinations to the pe
39、rformance 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 approximately30 min using
40、a fit-for-use instrument.7 Ross, Stephen, “Peirces Criterion for the Elimination of Suspect Experimental Data,” Journal of Engineering Technology, Fall 2003.D7668 14a36. Interferences6.1 WarningMinimize exposure of sample fuels, calibration reference materials, QC samples, and check standards tosunl
41、ight or fluorescent lamp UV emissions to minimize induced chemical reactions that can affect the delay measurements.86.1.1 Exposure 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
42、 peroxide and radicals can affect ignition delay measurement. These formations are minimized when the sample or materialis stored 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 ana
43、lytical measurement system9 comprised of:7.1.1 Combustion ChamberA cylindrical chamber having a volume of 0.473 6 005 L, with 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 i
44、njection nozzle assembly and there are openings at the other end of the chamber to insert air, remove exhaust, and attacha pressure 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 i
45、njector. A sample reservoir supplies the pressure multiplier with sample to ensure properand repeatable injection of calibration, 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
46、Hydraulic PumpCapable of producing fuel pressures up to 19 MPa.7.1.2.3 Pressure Multiplier10:1 ratio.7.1.2.4 Fuel InjectorAsolenoid-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 e
47、xceeds 180 MPa. The burst disk is attached to thehigh pressure sample system manifold block opposite the injector.7.1.2.6 Flush 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 inj
48、ector nozzleand dynamic pressure sensor. The system includes an auxiliary heat exchanger with built-in circulating pump and flow 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
49、 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 measure the pressure of the sample injected into thecombustion chamber.7.1.4.4 Nitrogen Pressure SensorA sensor installed to measure the inlet pressure from the nitrogen regulato
