Automotive fuels - Diesel fuel - Cold operability testing and fuel performance correlation

This document lays down the results of a study on the field correlation of the different cold operability (cold flow and cloud point) test results in relation to actual fuel performance in engines in real world cold conditions. For this work historical data on both manual and automatic tests and on 1988, current and, if possible, future engine concepts shall be used. Real market distillate fuels and FAME, plus common blends thereof, shall be used.

Dieselkraftstoffe für Kraftfahrzeuge - Prüfung der Betriebsfähigkeit bei Kälte und Zusammenhang des Kraftstoffverhaltens

Goriva za motorna vozila - Dizelsko gorivo - Odvisnost med hladnim obratovalnim preskušanjem in učinkovitostjo goriva

Ta dokument obravnava rezultate študije o odvisnosti med različnimi rezultati preskusov hladnega obratovanja (hladni tokokrog in motnišče) v povezavi z dejansko učinkovitostjo goriva v motorjih v realnih nizkotemperaturnih pogojih. Pri tem delu je treba uporabljati zgodovinske podatke o ročnih in avtomatskih preskusih ter konceptih motorjev iz leta 1988, trenutnih konceptih in prihodnjih, če je mogoče. Uporabljati je treba realna tržna destilatna goriva in njihove splošne mešanice.

General Information

Status
Published
Publication Date
16-Feb-2016
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
17-Feb-2016
Due Date
04-Jan-2016
Completion Date
17-Feb-2016

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SLOVENSKI STANDARD
01-april-2016
*RULYD]DPRWRUQDYR]LOD'L]HOVNRJRULYR2GYLVQRVWPHGKODGQLPREUDWRYDOQLP
SUHVNXãDQMHPLQXþLQNRYLWRVWMRJRULYD
Automotive fuels - Diesel fuel - Cold operability testing and fuel performance correlation
Dieselkraftstoffe für Kraftfahrzeuge - Prüfung der Betriebsfähigkeit bei Kälte und
Zusammenhang des Kraftstoffverhaltens
Ta slovenski standard je istoveten z: CEN/TR 16884:2016
ICS:
75.160.20 7HNRþDJRULYD Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 16884
TECHNICAL REPORT
RAPPORT TECHNIQUE
February 2016
TECHNISCHER BERICHT
ICS 75.160.20
English Version
Automotive fuels - Diesel fuel - Cold operability testing and
fuel performance correlation
This Technical Report was approved by CEN on 17 August 2015. It has been drawn up by the Technical Committee CEN/TC 19.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16884:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 7
2 Cold flow additives . 7
2.1 Application . 7
2.2 Storage, handling and blending of cold flow additives . 14
3 Cold flow tests . 19
3.1 Vehicle operability . 19
3.2 Assessment of vehicle operability . 20
3.3 Low temperature operability rigs . 20
3.4 Diesel cold flow test methods . 24
3.5 Summary of improvements made to the CFPP test in the past 15 years . 34
4 Fuel Quality Trends . 39
4.1 Changes to fuel production . 39
4.2 Fatty Acid Methyl Esters . 42
4.3 Hydroprocessed Vegetable Oils (HVO) . 45
4.4 Synthetic Paraffinic Diesel (GTL/BTL) . 48
4.5 Distillate Demand Changes . 49
4.6 National cold flow choice . 50
4.7 Winter Diesel Fuel Surveys . 54
5 Vehicle fuelling systems . 59
5.1 Fuel system development . 59
5.2 Vehicle fuel system design considerations in terms of cold operability . 66
5.3 Development of fuel filters . 72
6 Vehicle operability issues experienced in the field . 73
6.1 Description of field issues . 73
6.2 Field issues during recent winters in Germany . 75
6.3 Field issues during recent winters in other European countries . 76
7 Correlation between vehicle operability and laboratory tests . 77
7.1 Introduction . 77
7.2 Summary of DGMK projects . 78
7.3 Daimler studies on German winter diesel fuel samples . 83
7.4 Opel studies . 89
7.5 Results and analysis of WG34 investigations of winter 2011/2012 samples. 90
8 Conclusions . 97
Bibliography . 100

European foreword
This document (CEN/TR 16884:2016) has been prepared by Technical Committee CEN/TC 19
“Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological
origin”, the secretariat of which is held by NEN.
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any
or all such patent rights.
In 2010, CEN/TC 19 adopted Resolution 2010/11 setting the title and scope of WG 34 which
were defined as follows:
Title: “Diesel fuel cold operability correlation”
Scope: “Develop a study on the field correlation of the different cold operability (cold flow and
cloud point) test results in relation to actual automotive diesel fuel performance in engines in real
world cold conditions. For this work historical data on both manual and automatic tests and on
1988, current and, if possible, future engine concepts shall be used. Real market distillate fuels and
FAME, plus common blends thereof, shall be used. The working group shall advice towards WG 14,
WG 31 and WG 24 on possible improvements towards their test methods and specifications. The
result of the group will be, as a minimum, the development of a Technical Report on "Cold
operability testing and fuel performance correlation".
In view of the parallel ongoing work within DGMK Project 764 “Cold flow properties of diesel
and operability of vehicles in winter”, this study is focusing on an investigation into the field
correlation of cold operability descriptors (e.g. CFPP, Cloud Point) with actual vehicle
performance. In addition the study is evaluating the impacts of fuel properties, cold flow
additives and blending, and vehicle technology on cold operability. Given the close relationship
between the work of WG 34 and the DGMK Project 764, a liaison between these groups has been
established throughout the drafting of this report.
WG 34 would like to acknowledge the significant contributions by members of the working
group who have contributed to the publication of this report.
Introduction
Low temperature operability of diesel vehicles is a common concern for all the stakeholders including the
vehicle manufacturers and the fuel suppliers. The stakeholders’ shared desire is to ensure that the end
user is able to operate their vehicle regardless of the ambient temperature conditions.
The Cold Filter Plugging Point (CFPP) method is included in EN 590 as a means to ensure vehicle
operability. As all European countries experience different climatic conditions, the limits for cold flow
properties of diesel fuel are decided by the National Standardisation Body of each member state within
the framework allowed by EN 590. For member states with temperate climates, a different grade of diesel
fuel with its corresponding CFPP limit is selected from Table 2 of EN 590:2013 for each season depending
upon the climatic conditions.
For member states with arctic or severe winter climates, a different class of diesel fuel is selected from
Table 3 of EN 590:2013 for each season depending upon the climatic conditions. In addition to a CFPP
limit, Table 3 also includes a maximum Cloud Point limit for each class of diesel, as well as different limits
for several other fuel properties (e.g. density, viscosity, distillation, cetane). Some member states also
select different climatic grades / classes for specific geographic regions within the country (for example
mountainous or colder regions). A lower density can result in diesel fuel with lower volumetric energy
content which can negatively impact vehicle volumetric fuel consumption. Thus a balance between
ensuring vehicle cold operability and fuel cost is needed.
The application of the CFPP test in middle distillate fuel specifications has facilitated a trade-off between
the needs of the market and the costs of the whole system for the customer (i.e. the investment costs in
the vehicle diesel fuel filter system and the recurrent costs of the fuel supply). To meet the CFPP
specifications without significantly decreasing the yield of middle distillate fuels, the use of cold flow
improver additives has been widely adopted by refineries.
Since the CFPP method was developed in the 1960s, several studies have been performed to develop
other laboratory methods in an attempt to improve upon the correlation with vehicle cold operability.
However this has proved difficult due to constantly changing diesel engine technologies which have
necessitated changes in vehicle fuel system design driven by ever more stringent emissions legislation
(e.g. the move to direct injection and common rail systems with high pressure pumps requiring changes
to fuel filter materials and efficiency). At the same time, middle distillate fuel production has changed
significantly over the years as refineries have had to meet increasingly tight fuel quality requirements (e.g.
reductions in sulfur content, density and polyaromatic hydrocarbons as well as the introduction of
biofuels and higher cetane requirements). Despite all these changes to the vehicles and the fuels, and the
development of alternative lab tests, the CFPP remains the foremost test used to protect the end user
from cold operability vehicle failures.
At the 37th meeting of CEN/TC 19/WG 24 (November 2009, Brussels) questions were again asked
regarding the correlation between cold flow tests and actual vehicle operability at low temperature. Some
participants thought that the situation had worsened due to the introduction of finer fuel filters and
FAME blending.
At the 38th meeting of CEN/TC 19/WG 24 (March 2010, Teddington) the WG 24 convenor and secretary
suggested a scope for a new working group to be formed. This was accepted by WG 24 and the proposal
was then forwarded to CEN/TC 19 members (CEN document N1451). The proposal was accepted by
CEN/TC 19 on 10 May 2010 (resolution 2010/11).
Following a number of vehicle operability issues experienced, for example during a cold period in the first
half of February 2012, in Germany and Austria in particular, a DIN-FAM “mirror” working group was set-
up in Germany as a taskforce to investigate the issue. A key outcome was the creation of a new DGMK
project 764 “Determination of Cold Operability of Diesel vehicles” to develop and execute a joint industry
project. Phase 1 was intended to evaluate several current vehicles from different OEMs to select a new
reference vehicle for operability testing. It was also proposed that Phase 2 would investigate the
development of a rig test and evaluate a wider range of different fuels in the selected reference vehicle.
CEN/TC 19/WG 34 is maintaining close contact with the DGMK project group.
This Technical Report covers operability and tests to assess diesel fuel performance below the
fuel cloud point. Although a high filter blocking tendency above the cloud point can have an
impact on vehicle operability at low temperature, the development of a lab test to identify this
specific issue is being pursued by CEN/TC 19/WG 31 rather than by WG 34.
Finally, it should be borne in mind that the refiners and vehicle manufacturers are not the only
stakeholders when it comes to ensuring low temperature vehicle operability. There are a number of other
stakeholders involved, including fuel blenders, fuel retailers, biofuel suppliers, cold flow additive
suppliers, vehicle fuel system manufacturers, motorists and standardisation bodies like CEN. With this in
mind, it is important that each stakeholder shares the responsibility for ensuring low temperature vehicle
operability.
1 Scope
This Technical Report lays down the results of a study on the field correlation of the different
cold operability (cold flow and cloud point) test results in relation to actual fuel performance in
engines in real world cold conditions (below the fuel's cloud point). For this work historical data
on both manual and automatic tests and
...

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