A transient fuel consumption model for non-road mobile machinery.

Biosystems Engineering(2005)91(2),139–147 doi:10.1016/j.biosystemseng.2005.03.011 PM—Power and

Machinery

A Transient Fuel Consumption Model for Non-road Mobile Machinery

Magnus Lindgren

Department of Biometry and Engineering,Swedish University of Agricultural Sciences,P.O.Box7032,SE-75007Uppsala,Sweden;

e-mail:Magnus.Lindgren@bt.slu.se

(Received1October2004;accepted in revised form10March2005;published online11May2005)

Non-road mobile machinery is used for a variety of different operations.The in-use fuel consumption of non-road mobile machinery depends on the actual operation performed,including transient behaviour,rather than the static load distribution commonly used in steady-state-based fuel consumption models.A recent study has shown that during fast transients,measured fuel consumption is up to twice as high as during the corresponding steady-state load conditions.The purpose of this work was to develop a calculation model that includes the transient effects on the overall fuel consumption.

The transient fuel consumption model was based on a semi-static model and extended with transient correction factors for both changes in engine speed and torque.A general conclusion of the work was that fuel consumption could be accurately estimated even during operations that are largely transient in nature. Moreover,the results showed that the model developed for transient fuel consumption could also be applied to emissions of carbon monoxide,hydrocarbons,nitrogen oxides and particulate matter.The average difference between recorded and calculated fuel consumption and emission amounts decreased from approximately30%for the semi-static model alone down to about5%when it was extended with the transient correction factors.

Published by Elsevier Ltd

1.Introduction

Emission factors are the basis of numerous different simulation models and national emission inventories. In both the EU and the USA,emission factors are used for estimating national anthropogenic emissions (US EPA,1997;EEA,2000).Member states of the European Union report annual national anthropogenic emissions inventories to the European Union and other international conventions such as the United Nations Framework on Climate Change(UNFCCC), and the United Nations Economic Commission for Europe(UNECE)Convention on Long Range Trans-boundary Air Pollution(CLRTAP)(UNFCCC,1992; EU,1999;UNECE,2002).In order to harmonise the data delivered,parties are encouraged to use the Intergovernmental Panel on Climate Change(IPCC) Guidelines for National Greenhouse Gas Inventories when estimating and reporting the annual national inventories(IPCC,1996).

Several computer programmes for estimating national emission amounts arising from road transport,for example Computer Programme to Calculate Emissions from Road Transport(COPERT III),have been developed within the European Environment Agency in order to assist the member states to develop consistent and comparable national emission inventories (EEA,2000).The main use of COPERT III is to calculate national traf?c emission estimates on a yearly basis.Total emissions are estimated from emission factors and activity data in the form of vehicle kilometres.The emission factors are divided into different categories depending on driving conditions, i.e.urban,rural and highway,and combined with average speed.

Emission factors commonly used in calculation programmes for emission estimates are often based on either standardised emission measurements such as the Federal Test Procedure(FTP)75test cycle for cars and light duty trucks or simulations of road traf?c and

Published by Elsevier Ltd

speci?c operations(Sjo din et al.,2003).Development of emission factors based on emission measurements from transient loads in chassis or engine dynamometers is time-consuming and expensive as they are only repre-sentative for the actual operation performed.

On the other hand,simulation models based on emission maps have the potential to adjust the emission factors according to the actual operation performed. However,engine maps developed from static measure-ments are unable to satisfactorily describe emissions from real-use of the engine or vehicle.Transient load conditions are often estimated by a succession of steady-state modes,thus describing the instantaneous steady-state fuel consumption and emissions.The difference between calculated steady-state values and real-use values including transient effects can be substantial (Hansson et al.,2003).Correction measures must be treated with caution and take the actual workload and changes in engine speed and torque into consideration. Within an ongoing EU project Assessment and Relia-bility of Transport Emission Models and Inventory Systems(ARTEMIS),transient correction functions are being developed in order to increase the accuracy of emission estimates for different driving condi-tions.Moreover,Hassle(1995)has taken the transient effects into consideration through different correction functions.

However,most attempts at quantifying and reducing emission amounts have been made on on-road vehicles (and some on non-road transport,i.e.rail,air and water-borne transport).Non-road mobile machinery, e.g.construction equipment and agricultural and forestry tractors,contribute an important proportion of the exhaust gas emissions in Europe and most other countries in the world.In Europe,non-road mobile machinery accounts for approximately20%of the total emissions of nitrogen oxides(EEA,2004).

Non-road mobile machines,including agricultural and forestry tractors,are used for a number of different operations.Some of the operations are largely transient in nature and result in varying loads on the engine,such as different loading operations,while others,like many soil tillage operations or road transport,are mainly of a less transient nature(Hansson et al.,1999;Ullman et al., 1999;EU,2002;Lindgren et al.,2003).Transient load conditions affect the fuel consumption and emission formation from diesel engines.Hansson et al.(2003) showed that the fuel ef?ciency decreased with the increasing transient part of the operation.During a lowaverage pow er-loading operation,the fuel con-sumption increased by13%compared with steady-state conditions.Several authors have studied the effects of transients in engine speed or torque on in-cylinder temperature,engine structural temperatures,boost pressure and mechanical governor(Rakopoulos et al., 1998;Rakopoulos&Giakoumis,1999;Benajes et al., 2000;Bane2002).All the authors found that the engine and engine equipment suffered from time lag periods from a fewseconds,e.g.in-cylinder temperature,boost pressure and governor setting,up to several hundreds of seconds,e.g.engine structural temperature.The effects of transient conditions on fuel consumption and exhaust gas emissions have also been studied by Lindgren and Hansson(2004)and Callahan et al.(1985a).

The use of a calculation model that includes both different driving conditions and the transient effects on fuel consumption and emissions may improve the quality of emission factors and emission inventories. Furthermore,detailed knowledge generated by such a model of the effects of transient conditions on the engine would be of vital importance for manufacturers of engines,transmissions and engine equipment such as turbochargers and electronic engine control units.The transmission characteristics are essential for the result-ing speed and torque variations in the engine while operating the vehicle.

The purpose of the present work was to develop a model that includes the effects of transients in engine load on the fuel consumption.Moreover,the model should be able to be used as a supplement to engine load models and steady-state-based emission models.

2.Materials and methods

2.1.Transient fuel consumption model

A transient fuel consumption model,which expresses the fuel consumption as a function of engine speed, engine torque and the rate of change(i.e.transients)in engine speed and torque,was developed.Time series of engine speed and torque data used as inputs to the model were expressed as the average engine speed and torque of two adjacent values.Moreover,the rates of change in engine speed d n and torque d t in sà1were calculated as the normalised change of engine speed or torque per second as shown by Eqns(1)and(2):

d n?

n iàn ià1

n ratedàn0

et iàt ià1T(1)

d t?

t iàt ià1

t max

et iàt ià1T(2)

where:n is engine speed in minà1with subscripts i,ià1, rated and0representing engine speed at current time, engine speed at previous time-step,rated speed and low idle speed respectively;t is torque in Nm with subscript

M.LINDGREN 140

max representing maximum torque;and t is time in seconds with subscripts as above.

The model was based on two different parts,a semi-static part and a transient correction part,as shown in Eqn(3):

Z t?Z sen;tT?e1tR ten;t;d n;d tTT(3) where:Z t is transient fuel consumption in g hà1,Z s is semi-static fuel consumption in g hà1,and R t is a dimensionless transient correction function.Transient fuel consumption data were derived for each time step and then integrated over time to obtain an accumulated value.In the?rst part,fuel consumption was calculated as if the transient effects were neglected,using engine speed and torque data as inputs to a matrix describing static fuel consumption for all possible combinations of engine speed and torque.In the second part,a correction factor due to transients in engine load was calculated as the sum of the individual correction factors due to transients in engine speed and torque,?rstly independent of each other and secondly as a synergism of the two as shown in Eqn(4):

R t?q net;d nTtq ten;d tTàcq net;d nTq ten;d tT(4) where:q n is a dimensionless correction factor due to transients in engine speed,q t is a dimensionless correction factor due to transients in engine torque, and c is a model-speci?c coef?cient.The correction factor for transients in engine speed was calculated using engine torque and rate of change in engine speed data as inputs to a matrix describing the correction factors for all possible combinations,within the operational range of the engine,of transients in engine speed during?xed engine torque.

Correction factors for transients in engine torque were calculated in the same way.The engine speed and torque data were limited to the operational range of the engine and rounded towards the nearest integer and the absolute rate of change was limited to a maximum of 0á50sà1and rounded towards the nearest hundredth. The matrices were obtained by a two-dimensional interpolation technique.Correction factors were derived for each time step and employed in Eqn(3).

2.2.Calibration of the model on a Valtra420DWRE engine

A Valtra420DWRE,a4-cylinder turbocharged diesel engine with a displacement of4á4l normally mounted on a Valtra6650agricultural tractor,was used in the calibration of the transient fuel consumption model.The rated power of the engine was81kW at 2200minà1and the maximum torque at1400minà1was 460Nm.Furthermore,the engine was equipped with a Standadyne distributor pump.The engine was delivered in the year2000and the measured amounts of emissions were less than the regulated levels in stage I,according to Directive2000/25/EC(EU,2000).

Fuel consumption and emissions were measured both during a20-mode steady-state test cycle and during synthetic transient test cycles.The steady-state test cycle was based on the8-mode ISO8178C1test cycle and extended with12additional modes uniformly distributed within the operational range of the engine, see Fig.1(ISO,1996).The average fuel consumption, according to the methodology stipulated in the ISO8178 regulation,was0á23kg kWhà1(Wetterberg,2003). Synthetic test cycles were developed in order to study the effect of transients on engine speed and engine torque independent of each other.The correction factors for transient load changes were calculated as the ratio of fuel consumption recorded during transient load changes to calculated fuel consumption as if the transient effects were neglected for the same load cycle. Tables1and2showthe correction factors for different rates of change in engine speed and torque on the fuel consumption for the Valtra420DWRE engine.All measurements were conducted in accordance with the ISO8178regulation and are described in more detail in Lindgren and Hansson(2004),(ISO,1996).

In addition to fuel consumption,emissions of carbon monoxide(CO),hydrocarbons(HC)and nitrogen oxides(NO x)were studied during the synthetic test cycles and correction factors for transients in engine speed and torque on exhaust emissions were established for the Valtra420DWRE engine.

The calibration of the structure of the transient fuel consumption model,i.e.the model speci?c coef?cient c, was based on time series of engine torque,speed and fuel consumption recorded for four different types of operations with varying degrees of fast variations in engine speed and/or torque with the Valtra6650tractor.

100

Engine speed, % of rated speed

Fig.1.The20-mode steady-state test cycle based on ISO8178 (n)and extended with12additional modes(?)

A TRANSIENT FUEL CONSUMPTION MODEL141

The tractor was equipped with strain gauge transducers for measuring engine torque at the shaft between the ?ywheel and the transmission.Furthermore,the tractor was equipped with a?ow sensor for measuring fuel consumption and a transducer for measurements of engine speed.A more thorough description of the measurement system can be found in Hansson et al. (2003).The operations recorded were:

(1)different combinations of?xed engine speed and

torque with a tractor and a17000kg trailer,the recorded time series including only short periods of acceleration from one?xed operating point to the next to minimise any transient effects;

(2)repeated acceleration tests with a17000kg trailer,

from stationary to the maximum attainable velocity in the highest gear of approximately35km hà1; (3)on-farm driving without any external load on the

tractor,the operation consisting of normal accelera-tions,decelerations and turns on a?at asphalt surface;and

(4)moving of gravel from one pile to another with a

front-end loader and a0á6m3bucket.

Changes in engine speed and torque caused by gear shifting,recorded at the shaft between the?ywheel and the transmission,had only limited effects on the fuel consumption as could be seen from the lowtransient operations,e.g.the operation including different com-binations of?xed engine speed and torque.Therefore, changes in engine speed and torque caused by gear shifting were omitted from the calculation of transient effects,i.e.the rate of change was set to zero during shifting.Moreover,rate of change in engine speed and torque exceeding50%sà1was limited to50%sà1.

2.3.Validation of the model on a Valtra420DWRE engine

One complete load cycle,see Fig.2,representing a front-end loading operation with the Valtra6650was distinguished and repeated in an engine test bench for validation of the proposed transient fuel consumption model.

Measured fuel consumption data were compared with calculated fuel consumption using the proposed tran-sient model and recorded engine speed and torque data. Furthermore,emissions of CO,HC and NO x were measured together with fuel consumption and the model was employed on those emissions as well.No changes were made in the structure of the model,the matrices describing fuel consumption data were only exchanged for corresponding matrices describing the various emissions.

2.4.Calibration and validation of the model on

a TD63KDE engine

The proposed model was employed on fuel consump-tion and emissions of CO,HC,NO x and particulate matter(PM)on a Volvo TD63KDE,a6-cylinder turbocharged diesel engine with a displacement of5á48l, normally mounted on a Volvo L70wheel loader.The rated power of the engine was91kW at2150minà1and the maximum torque at1100minà1was624Nm.Unlike the Valtra420DWRE,the Volvo TD63KDE engine was equipped with an in-line pump.The engine was delivered in1999and the measured amounts of emissions were less than the regulated levels in stage I, according to Directive97/68/EC(EU,1997).

The TD63KDE engine was tested according to a load cycle reported by Lindgren et al.(2003).The operation performed was gravel loading to a grading sieve at a quarry.Measured fuel consumption and emissions of CO,HC,NO x and PM were compared with both calculated semi-static values and transient values

Table1

Correction factors for transients in engine speed on the fuel consumption from a Valtra420DWRE engine

Rate of change in engine speed,%sà1

Correction factor for fuel

consumption(q n)

100Nm250Nm350Nm

250á750á790á94 150á830á870á95 100á850á880á96 01á001á001á00à101á221á081á18à151á321á091á32à251á761á341á82

Table2

Correction factors for transients in engine torque on the fuel consumption from a Valtra420DWRE engine

Rate of change in engine torque,%sà1

Correction factor for fuel

consumption(q t)

1600minà12000minà1

251á321á47 151á081á22 101á081á15 01á001á00à101á081á14à151á221á32à251á611á81M.LINDGREN

142

derived from the proposed transient calculation model. No changes were made in the structure of the model.

2.5.Example of implementation on an engine load simulation model

The transient fuel consumption and emission model was incorporated into a mechanistic engine load simulation model.The engine load simulation model presented by Lindgren and Hansson(2002)describes the engine speed and torque load of a Valtra6650 performing soil cultivation and transport.The engine load simulation model was based on Newton’s second lawin order to determine the speed of the tractor in relation to obtainable motive power and actual work-load with a time step of0á1s.Simulated engine load data were used as inputs to the transient fuel consumption and emission models.

3.Results

3.1.Calibration of the model on a Valtra420DWRE engine

The coef?cient c used in the transient fuel consump-tion model was varied from0to4in steps of1and the absolute difference between measured and calculated fuel consumption is presented in Table3for the four operations with the Valtra420DWRE engine.

The best overall?t to the measured data was obtained when the coef?cient equalled2.Table4shows recorded fuel consumption and calculated fuel consumption both from the semi-static part alone and from the whole model including the transient correction function.

3.2.Validation of the model on a Valtra420DWRE engine

The result of the validation of the transient fuel consumption model is shown in Table5for the Valtra 420DWRE engine.The results of the transient fuel consumption model employed on emissions of CO,HC and NO x are presented in the same table.

The proposed model,calibrated against fuel con-sumption data for four different operations,resulted in accurate estimates of both fuel consumption and emissions of CO,HC and NO x.The average difference between measured and estimated amounts was about 5%,a decrease in the error of estimate from almost30% using the semi-static part of the model only.

3.3.Calibration and validation of the model on

a TD63KDE engine

The proposed model was employed on a loading cycle with the TD63KDE engine and the results are shown in Table6.Both measured and calculated fuel consump-tion and emissions of CO,HC,NO x and PM are presented.

The inclusion of a transient correction function in the semi-static calculation model improved the accuracy of the estimate of real-use fuel consumption and emissions of HC,NO x and PM considerably.In some cases the transient model increased the calculated steady-state-based emissions amounts by almost50%.However, real-use emissions of CO from the Volvo L70wheel

Fig.2.Engine speed and torque variation during a front-end loading operation with the Valtra6650agricultural tractor:——,

torque;––,speed

A TRANSIENT FUEL CONSUMPTION MODEL143

loader showed a major diversion from the estimated values,both in the semi-static model and in the transient model.

3.4.Example of implementation on an engine load simulation model

Calculated steady-state based and transient fuel consumption and emission data from the simulated engine load during soil cultivation and transport are shown in Table7.

The engine speed and torque variation generated by the simulation model presented by Lindgren and Hansson(2002)included transient effects on both fuel consumption and emissions.The occurrence of transi-ents,and thus the effects of transients,was more pronounced during the transport operation.

4.Discussion

A general result of the work is that by conducting a limited amount of measurements in an engine dynam-ometer,it is possible to accurately estimate fuel consumption and emission factors for all types of operation and use of a speci?c engine.However,as with all engine maps,the emission matrices used in the model only describe the emission characteristics for a speci?c engine.

Although the model was calibrated against fuel consumption data for the Valtra420DWRE engine,it also resulted in reliable estimates of emissions of CO, HC and NO x for the same engine.This indicates that the structure of the model is valid for both fuel consumption and emissions.Moreover,the model applied on another engine,a Volvo TD63KDE,resulted in accurate estimates of fuel consumption and emissions of HC,

Table3

In?uence of the coef?cient c on the absolute difference between calculated and recorded transient fuel consumption in per cent Coef?cient(c)Difference between calculated and measured consumption,%

Static Acceleration Transport Front-end loader Average value 00á20á92á24á92á1

10á20á72á02á81á4

20á20á61á80á50á8

30á20á61á71á41á0

40á30á71á62á81á4

Table4

Recorded and calculated fuel consumption for the recorded time

series of engine load use in the calibration for the transient fuel

consumption model

Operation Recorded

consumption,g hà1Calculated consumption,

g hà1

Semi-static Transient

Static920091709220 Acceleration128401245012920 Transport655060806670 Front-end

387033503890

Table5

Measured and calculated fuel consumption and emission amounts,both with the semi-static part of the model alone and with the whole model including the transient correction function, for a front-end loading operation with a Valtra420DWRE engine;HC,hydrocarbons;NO x,nitrogen oxides

Fuel, kg hà1CO,

g hà1

HC,

g hà1

NO x,

g hà1

Measured4á0730á39á3497á1 Calculated with:

Semi-static3á2721á86á5163á8 Transient4á0231á310á087á1

Table6

Measured and calculated fuel consumption and emission amounts,both with the semi-static part of the model alone and with the whole model including the transient correction function, for a moving material operation with a Volvo TD63KDE engine;HC,hydrocarbons;NO x,nitrogen oxides;PM,particu-

late matter

Fuel,

kg hà1

CO,

g hà1

HC,

g hà1

NO x,

g hà1

PM,

g hà1 Measured9á8266á59á863328á21 Calculated

with:

Semi-static8á8827á86á662384á02 Transient9á8733á110á43428á03

M.LINDGREN 144

NO x and PM.The average error of the estimate was less than3%,thus strengthening the accuracy of the proposed model further.

The proposed model could be used in a wide?eld of applications.For example,it could be used for estimat-ing emission factors for different traf?c conditions or operations to be used as input data in other models with a lower aggregation level,both temporally and spatially. This will result in a base for more accurate estimates of the contribution from non-road mobile machinery to the overall national anthropogenic emissions.Moreover, the proposed model could be used to derive operation-speci?c fuel consumption and emission data used in for example life-cycle assessments methodologies or to estimate the in?uence of different engine control strategies or transmission characteristics on the occur-rence of transient loads and thus the fuel consumption and emission formation.

The proposed model could also be used together with vehicle simulation models that generate instantaneous engine speed and torque data.Furthermore,transient exhaust gas emission data will probably be useful in simulations of the response of transient exhaust gas loads on the function of different equipment for post-engine treatment of exhaust gas emissions or the effects of alternative transmissions,such as a continuously variable transmission(CVT),on the engine load and emission amounts.A CVT is,theoretically,able to change the gear ratio during transient conditions and keep the optimal engine power trajectory relatively constant over time,thus minimising the transient effects on the engine(P?ffner et al.,2003).

Transient engine loads affect both the fuel consump-tion and emission formation from diesel engines as shown by several authors(Callahan et al.,1985a,1985b, 1987;Arcoumanis et al.,1994;Vachtsevanos&Boukas, 2001;Hansson et al.,2003,Lindgren et al.,2003, Lindgren&Hansson,2004).The results from the calibration of the transient fuel consumption model showed a good correlation between recorded and calculated fuel consumption,see Table4.The contribu-tion from the transient part of the calculation model during lowtransient operations,i.e.the static operation, was negligible.However,during high transient opera-tions the transient fuel consumption model gave a considerable contribution to the resulting fuel consump-tion.In all measurements conducted,the transient fuel consumption model resulted in a better estimate of the real fuel consumption compared to the semi-static part of the model alone.

The transient calculation model was designed to meet some elementary boundary conditions,namely that steady-state fuel consumption is needed at steady-state operation,and that during changes in only engine speed or torque the effects on the fuel consumption are fully allocated to the resulting fuel consumption.The in?uence of synergy effects due to changes in both engine speed and torque was simultaneously considered through the coef?cient c.No speci?c measurements of synergy effects were conducted.However,the recorded operations used for calibration and validation purposes were based on the real use of the engine and thus included synergy effects.The coef?cient was set to an integer in order to simplify the empirical model.

The comparatively large difference between recorded and calculated emissions of CO,both steady-state based and transient,from the Volvo L70wheel loader, depended on the engine characteristics of the TD63 KDE engine.At lowengine speeds in combination w ith high loading torque,the TD63KDE engine suffers from lowair supply,thus causing high levels of CO emission even at steady-state,which the semi-static model was unable to reproduce.At those engine loads the air utilisation was almost100%.

The resulting fuel consumption data obtained from the simulated soil cultivation operation and transport operation agree with the effects of transient loads on the fuel ef?ciency presented by Hansson et al.(2003)and Lindgren et al.(2003).Soil cultivation can be considered as a fairly static operation with rather slow changes in engine speed and torque,while a transport operation includes more transient loads.The fuel ef?ciency and the difference between calculated semi-static fuel consump-tion and calculated transient fuel consumption,de-creased by2á4%and5á3%when transient effects were included for the soil cultivation operation and the transport operation,respectively.

The simulated transport operation was a heavy transport,14600kg including trailer,and thus re-sembled the recorded acceleration operation rather than the recorded on-farm transport operation.This is also shown in the calculated fuel consumption from the simulated transport operation.Both the absolute fuel

Table7

Calculated fuel consumption and emission amounts,both with the semi-static part of the model only and with the whole model including the transient correction function,from simulated engine load data for two operations with a Valtra6650 agricultural tractor;HC,hydrocarbons;NO x,nitrogen oxides

Fuel, kg hà1CO,

g hà1

HC,

g hà1

NO x,

g hà1

Soil cultivation:

Semi-static15á412510á6798

Transient15á813912á3850

Transport:

Semi-static12á160á510á9481

Transient12á868á713á1525

A TRANSIENT FUEL CONSUMPTION MODEL145

consumption and the transient effect were close to that of the recorded acceleration operation.

Due to the difference in the fuel consumption and emission data used,steady-state-based fuel consumption and emission values presented by Lindgren and Hansson (2002)and those calculated with the semi-static model, presented in Table7,will diverge.The data used by Lindgren and Hansson(2002)were based on values measured at only eight operating points,according to the ISO8178standard,(ISO,1996)while the current study employed20modes evenly distributed within the operational range of the engine.Furthermore,the?eld data used in the soil cultivation scenario were recalcu-lated at a higher frequency in order to re?ect the transient load variations during soil cultivation.

5.Conclusions

A general result of the work is that by conducting a limited amount of measurements in an engine dynam-ometer,it is possible to estimate fuel consumption and emission factors for all types of operation and use of a speci?c engine with high accuracy.In all measurements conducted,the transient fuel consumption model resulted in a better estimate of the real fuel consumption compared to the semi-static model.The error of the estimate decreased from30%using the semi-static model alone down to about5%for the transient model. Although the model was optimised and calibrated against fuel consumption data from one engine,the results showed that the model could be employed on other engines with good results.Furthermore,the transient fuel consumption model could also be em-ployed on emissions of CO,hydrocarbons(HC), nitrogen oxides(NO x)and particulate matter(PM). References

Arcoumanis C;Megaritis A;Bazari Z(1994).Analysis of transient exhaust emissions in a turbocharged vehicle diesel engine.Institution of Mechanical Engineers Paper C484/ 038/94

Bane B(2002).A comparison of steady state and transient emissions from a heavy-duty diesel engine.MS Thesis, Department of Mechanical and Aerospace Engineering, West Virginia University,USA

Benajes J;Luja n J;Serrano J(2000).Predictive modeling study of the transient load response in a heavy-duty turbocharged diesel engine.Society of Automotive Engi-neers,SAE Technical Paper Series No2000-01-0583 Callahan T;Ryan T;Dietzmann H;Waytulonis R(1985a).The effects of discrete transient in speed and load on diesel engine exhaust emissions.Society of Automotive Engineers, SAE Transactions Paper No850109,pp1646–1657Callahan T;Ryan T;Dietzmann H;Waytulonis R(1985b).The effects of engine and fuel parameters on diesel engine exhaust emissions during discrete transient in speed and load.Society of Automotive Engineers,SAE Transactions Paper No850110,pp1658–1671

Callahan T;Ryan T;Martin S;Waytulonis R(1987). Comparison of predicted and measured diesel exhaust emission levels during transient operation.Society of Automotive Engineers,SAE Transactions Paper No 872140,pp7846–7853

EEA(2000).COPERT III computer programme to calculate emissions from road transport,methodology and emission factors.Technical Report No49,European Environment Agency,Copenhagen,Denmark

EEA(2004).EMEP/CORINAIR Emission Inventory Guide-book,3rd Edn,September2003Update.Technical Report No30European Environment Agency,Copenhagen,Den-mark

EU(1997).Directive97/68/EC of the European Parliament and of the Council of16December1997on the approxima-tion of the laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery.Of?cial Journal of the European Com-munities L059,1–86

EU(1999).Council decision of26April1999amending Decision93/389/EEC for monitoring mechanism of com-munity CO2and other greenhouse gas emissions.Of?cial Journal of the European Communities L117,35–38

EU(2000).Directive2000/25/EC of the European Parliament and of the Council of22May2000on action to be taken against the emission of gaseous and particulate pollutants by engines intended to power agricultural or forestry tractors and amending Council Directive74/150/EEC.European Union Of?cial Journal L173,1–34

EU(2002).Proposal for a Directive of the European Parliament and of the Council amending Directive97/68/ EC on the approximation of the Laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery.Legislation in preparation No.765,Of?cial Publications of the European Communities,Luxembourg

Hansson P-A;Lindgren M;Nordin M;Pettersson O(2003).A methodology for measuring the effects of transient loads on the fuel ef?ciency of agricultural tractors.Applied Engineer-ing in Agriculture,19(3),251–257

Hansson P-A;Nore n O;Bohm M(1999).Effects of speci?c operational weighting factors on standardized measure-ments of tractor engine performance.Journal of Agricultur-al Engineering Research,74,347–353

Hassle D(1995).Emission factors for heavy duty vehicles. Management committee of the COST action319.European Commission,DG VII,EURO-COST/319/95,Brussels, Belgium

IPCC(1996).Revised1996Intergovernmental Panel on Climate Change Guidelines for National Greenhouse Gas Inventories.Geneva,Switzerland

ISO(1996).ISO8178-4;Reciprocating Internal Combustion Engines—Exhaust Emission Measurements—part4:Test Cycles for Different Engine Applications.International Organisation of Standardisation,Geneva,Switzerland Lindgren M;Hansson P-A(2002).Effects of engine control strategies and transmission characteristics on the exhaust

M.LINDGREN 146

gas emissions from an agricultural tractor.Biosystems Engineering,83(1),55–65,doi:10.1006/bioe.2002.0099 Lindgren M;Hansson P-A(2004).Effects of transient conditions on exhaust emissions from two non-road diesel engines.Biosystems Engineering,87(1),57–66,doi:10.1016/ j.biosystemseng.2003.10.001

Lindgren M;Pettersson O;Hansson P-A;Nore n O(2003). Jordbruks-och anla ggningsmaskiners motorbelastning och avgasemissioner samt metoder att minska bra nslefo rbrukn-ing och avgasemissioner[Engine load pattern and engine exhaust gas emissions from off-road vehicles and methods to reduce fuel consumption and engine exhaust gas emissions.] Report Agriculture and Industry308,Swedish Institute of Agricultural and Environmental Engineering,Uppsala, Sweden

P?ffner R;Guzzella L;Onder C(2003).Fuel-optimal control of CTV powertrains.Control Engineering Practice,11, 329–336

Rakopoulos C;Giakoumis E(1999).A computer program for simulating the steady-state and transient behaviour of direct-acting engine governors.Advances in Engineering Software,30,281–289

Rakopoulos C;Mavropoulos G;Hountalas D(1998).Modeling the structural thermal response of an air-cooled diesel engine under transient operation including a detailed thermody-namic description of boundary conditions.Society of Automotive Engineers,SAE Technical Paper Series No 981024

Sjo din(A;Flodstro m E;Ekstro m M;Grennfelt P(2003). Nationell emissionsstatistik fo r va gtra?ksektorn—o kad

kvalitet,trova rdighet och konsensus.Fo rstudie[National emission statistics for the road transport sector—improved quality,credibility and consensus.]IVL Report B1537,IVL Swedish Environmental Research Institute Ltd,Gothen-burg,Sweden

Ullman T;Webb C;Jackson Jr C;Doorlag M(1999).Nonroad engine activity analysis and transient cycle generation. Society of Automotive Engineers,SAE Technical Paper Series No1999-01-2800

UNECE(2002).Draft guidelines for estimating and reporting emission data.Executive body of the convention on long range transboundary air pollution.General EB.AIR/GE.1/ 2002/7,Twenty-sixth Session,2–4September2002,Geneva, Switzerland

UNFCCC(1992).United Nations Framework Convention on Climate Changes.United Nations,Geneva,Switzerland US EPA(1997).Procedures for preparing emission factor documents.Of?ce of Air Quality Planning and Standards Of?ce of Air and Radiation.U.S.Environmental Protection Agency,EPA-454/R-95-015.North Carolina, USA

Vachtsevanos G;Boukas T(2001).Modeling and control of transient engine conditions.Society of Automotive En-gineers,SAE Technical Paper Series No2001-01-3231 Wetterberg C(2003).EMMA—Emissioner fr(a n arbetsmaski-ner—delrapport2:Ma tning av emissioner vid dynamiska fo rlopp[Measurements of emissions during transient con-ditions.]Report Agriculture and Industry307,Swedish Institute of Agricultural and Environmental Engineering, Uppsala,Sweden

A TRANSIENT FUEL CONSUMPTION MODEL147