Shaping the Future Engine Testing & Vehicle Emissions Testing

Shaping the Future

Engine Testing &

Vehicle Emissions Testing

Why Test an Engine?

Engine testing occurs during the design and development phase of an engine’s life cycle. Testing occurs for a range of different objectives;

1. Combustion Chamber Development

2. Base Engine Development

3. Calibration

4. Durability

5. Certification

Engine testing generally precedes the availability of the vehicle, hence it is partially undertaken within a test cell.

The Engine Test Cell

Example – AVL Engine Test Cell at Millbrook


Example – Passenger CarFull Transient, Low Inertia, Gaseous EmissionsRated Power 220kW at 4,500 rpmRated Torque 467 Nm, Max Spd 12000 rpmFuels: Petrol, Diesel, Bio

Example – Heavy Duty TruckFull Transient, Low Inertia, Conditioned Air, Gas & Particulate Emissions Max Power 340kW at 1,500 rpmMaximum Torque 2165 Nm, Maximum Speed 3,500 rpmFuels: Diesel, Biodiesel


Example – Industrial/Marine Diesel

Example – Single Cylinder Research (Optical) Engine


Engine

Dynamometer (Dyno) Load Absorbing and Measuring Machine

Torque Arm

Trunnion Bearings

Rotor

Stator

Load Absorption via Electrical Power Generation

AC or DC Power

http://en.wikipedia.org/wiki/File:Dynamometer01CJC.svg


Eddy Current DynamometerLoad Control via magnetic field flux

Loss plates need cooling

Torque reaction measured with load cell

Good for steady state testing


AC Dynamometer

Essentially an electrical generator

Low Inertia

High Speed

Produces electricity – can be fed back into the grid or dumped via resistance loads

Engine Torque

Early Torque Measurement using counter balance

weights

Load Cell on the torque arm


Dynamometer Operating Envelopes (“Dyno Curves”)

0

50

100

150

200

250

300

0

100

200

300

400

500

0 2000 4000 6000 8000 10000 12000

Po

we

r k

W

To

rqu

e N

m

Engine Speed (rpm)

Torq

ue (N

m)

Pow

er (

kW)

Engine Speed (rpm)


Dynamometer Operating Modes

Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power


Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power

Vibration Isolation

Electrical Power Absorption

Seismic Mass


Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power

Combustion Air Handling

•System Design Flow Rate 1000 m3/Hr•Pressure Gain Max 120 mBar @ 450 m3/Hr•Pressure Gain @ Max Flow 105 mBar @ 900 m3/Hr•Humidifier 5-20 kg/Hr•Cooling Coil Capacity 5-30 kW•Example Temp Drop 45 Deg C In to 8 Deg C Out

Intake Air Pressure, Temperature and Humidity Control



Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power



Fuel Supply and Return

Fuel Conditioning &

Mass Flow Measurement

Circulating Pump Selector Valves Header Tank Immersion Heater Flat Plate Heat Exchanger fed by Chilled Water Circuit Temperature and Level Sensors

Fuel Conditioning


Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power




Fuel Conditioning &


Fuel Mass Flow Measurement

Gravimetric Fuel Mass Meter Coriolis Fuel Mass Meter


Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power


Engine Oil & Water Cooling (Shell & Tube Heat

Exchangers)

Raw Water Supply

Cooling Towers,

Fans



Fuel Conditioning &


Cooling Post


Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power


Exhaust Extraction and Emissions Measurement


Exchangers)

Raw Water Supply

Cooling Towers,

Fans


Fuel Conditioning &



Engine Torque Arm

Trunnion Bearings

Rotor

Stator

AC or DC Power


Exhaust Extraction and Emissions Measurement


Exchangers)

Raw Water Supply

Cooling Towers,

Fans

Seismic Mass



Fuel Conditioning &


Test Cell Air Handling

Instrumentation

Cylinder Pressure Measurement– Piezo Crystal

Cylinder Pressure Measurement

Thin layer of treated quartz crystal that produces an electrical charge when compressed

High natural frequency (~70 KHz)Water cooling may be required

Instrumentation

Speed - Encoders

Principle of Operation

Test Procedures - example

SAE J1349Engine Power Test CodeSpark Ignition and Compression Ignition

Net Power Rating

(Equivalent to ISO 1585)


SAE J1349Net Power Rating “Net Power”

The power and torque produced by an engine at any speed when configured as a “fully equipped” engine, corrected to the reference atmospheric conditions and reference fuel specifications, and tested in accordance to the applicable procedures contained in this standard.


SAE J1349Net Power Rating

“Net Power”The power and torque produced by an engine at any speed when configured as a “fully equipped” engine, corrected to the reference atmospheric conditions and reference fuel specifications, and tested in accordance to the applicable procedures contained in this standard.

“Fully Equipped”

Air Cleaner/Filter

Cooling Pump

Cooling Fan (behind a standard radiator)

Lubrication Oil Pumps

Power Steering Pump (at minimum setting)

Alternator (electrically loaded to power

essential engine needs – e.g. Fuel pump)

Fuel Supply Pump




Reference Atmospheric Conditions




Reference Fuel

Regular Fuel Mid Grade Premium

RON (+/- 0.5) 92 93 97

MON (+/- 0.5) 83 85 87

LHV (+/- 0.1) 43.3 MJ/kg 43.3 MJ/kg 43.1 MJ/kg




ProceduresInstrument Accuracy

Test Points Every 500 rpm Every 100 rpm near maximum peak torque and peak power Speed steady to +/- 5 rpm

Report Standard format

Global Exhaust Pollution Regulation

Three principle regulatory bodies; Californian Air Resource Board (CARB) United States Environment Protection Agency (EPA) European Union

Approaches; Regulation limits mass of specified pollutant per mile or kilometre

travelled per vehicle Type Approval - Verified Testing of Representative Vehicle (EU) Self Certification & Fleet Average – Body of Evidence (CARB & EPA)

California (CARB) - LEV II Standards (Low Emissions Vehicle) to 2019US Federal (EPA) - Tier 2 Standards European Union (EU) – Euro 5 Standards, Euro 6 from 2014

EU Regulated Emissions

www.dieselnet.com

US Federal Regulated Emissions

www.dieselnet.com

Vehicles have to comply with one of the Permanent Bins plus the Fleet Average of 0.07 g/mile for NOx

Californian Regulated Emissions

Low Emission Vehicles (LEV)Ultra Low Emission Vehicles (ULEV)Super Ultra Low Emission Vehicles (SULEV)


• Non Legislative Emissions Measurement for Engine Development Purposes

• Measurement of Regulated Gaseous & Particulate Engine Emissions per Vehicle

• Measurement of Regulated Total Vehicle Hydrocarbon Emissions





Non Legislative Emissions Measurement Raw (engine out) Emissions for development purposes only

Raw Gas Sampling

Provides gas concentration measurements (ppm, %) from an integrated gas handling and sampling system

Continuous raw gas sampling and analysis is sometimes called modal analysis

Typical continuous sample trace (for NOx). Note – exhaust mass flow has been included

Raw Emissions Measurement

Gas Emissions Concentration Measurement

Review some of the techniques, See slides at end of presentation .





Regulated Gaseous & Particulate Engine Emissions

General PrinciplesHC (NMOG) , CO, NOx, Particulates

Mass per mile or kilometre for prescribed vehicle journey (Cycle)

Measurement of ambient air diluted emissions

Global Variations

Within California – HC Speciation

At ambient and sub ambient (-7 Deg C) conditions

Legislative Emissions Measurement

Vehicle based measurement of air diluted exhaust gas and particulates are the norm

The test vehicle undertakes a journey (over a test cycle) on a vehicle dynamometer (or chassis rolls) during which a bag of diluted emissions is collected

At the end of the journey a sample of the diluted exhaust gas is taken from the bag and analysed

The pollutant concentrations are converted to average masses per kilometre (or mile) and compared with legislative limits.

Passenger Cars;



Air dilution is with a Constant Volume Sampling System (CVS)

The orifice flows sonic

CVS Sampling System

Test Cycles

Japan 10-15 ModeEuropean NEDC (EDC & EUDC )

USA FTP 75

Test CyclesWorldwide Harmonized Light Vehicles Test Procedure (WLTP) – under development by the UN ECE GRPE (Working Party on Pollution and Energy) group

Different Cycles for different Classes of Vehicles

Class 3 – High Power to Mass ratio. Typical of Europe & Japan

Class 2 - Representative of some vehicles driven in India and of low power vehicles driven in Japan

Class 1 - Lowest power-to-mass ratio. Representative of most vehicles driven in India.

Class 3 WLTP Cycle

Partial Flow Systems

A lower cost alternative to diluting all of the exhaust gas – and then extracting a sample for analysis A controlled sample of exhaust gas is extracted and diluted with a controlled flow of ambient dilution air.

The flow controllers must maintain a constant exhaust gas sampling and air dilution ratios throughout the test cycle

Often called mini-diluters

Bag Mini Diluter (BMD)

AVL’s mini diluter with integral bag collection system

Dilution Air Clean Up

Require to clean the dilution air to at least 0.1 ppm concentration on all measured pollutants

Can be extremely expensive

As an alternative could use bottled air with mini dilution systems

Background dilution air can be more polluted than the exhaust gas

Diesel Particulate Sampling

Diesel Particulate Sampling

Exhaust gas is diluted within a mixing (or dilution) tunnel

A sample of the gas is passed over filter papers

The filter papers are weighed under controlled conditions

http://www.emd.horiba.com/engmeas/p_image/afic1400_closeup_big.jpg

Particulate Size Measurement

Two types of Measurement TechniquesElectrical Mobility Particle Sensor

Cascade Impactors

Electrical Mobility Particle SensorMeasure of a charged particle’s tendency to deflect when passing through an electric field. Measured value – ‘mobility’ or Stokes diameter (tends to be larger than aerodynamic diameter)

Cascade ImpactorMeasure of charged particles momentum (mass x velocity) when impacted against cross flow plates.

Electrical Mobility Particle Analyser

Particles are given an electrical charge

The charged particles pass through an electrical field

The particles with the greater mass pass the furthest through the field

Example; SMPS – Scanning Mobility Particle Sizer

Electrical Low Pressure Impactor

The multi stage cascade impactors sort the particles into size ranges

Corona discharge gives particles an electric charge

The quantity of particles caught in each cascade is determined by the measured electrical current

Measurement range typically 10 nm to 32 microns

Heavy Duty Truck

Vehicle based emissions testing for heavy duty trucks (~ 40 tonnes +) is generally impractical - exception Millbrook !

Instead, emissions testing is undertaken within the engine test cells

The engine is operated over the ESC (European Stationary Cycle) and the ETC (European Transient Cycle)

The ESC requires the engine to be run at specific speed/load points for set periods of time,

Exhaust gas is collected and analysed in the same manner as the vehicle based tests

ESC Cycle Test Points (13 mode)

Heavy Duty Truck

European Transient Cycle (ETC) also known as the FIGE Transient Cycle





Total Vehicle HC Emissions

Variable Temperature SHED

Atmospheric HC pollution is emitted from all parts of the vehicleMeasurement is undertaken in a Sealed Housing for Evaporative Determination (SHED) enclosure

Vehicle subjected to daily (diurnal) temperature cycles

Hydrocarbon concentration within the SHED is measured

Volume compensation bags

Thank you for listening

Gas Measurement Principles

Non Dispersive Infra Red (CO, CO2)

Black body infra-red radiation emitters

Reference Inert Gas (N2)

Chopper Plate (10 Hz)

Sample Gas

Compensator

Measurement cell with pure gas (CO or CO2) and capacitance based differential pressure sensor (C & S)

The sample gas absorbs IR energy in accordance with its CO or CO2 concentration so having less energy to heat up half of the pure gas cell (D) hence causing a pressure difference between the two halves of the cell.

Chemiluminescence (NO, NOx)

Nitric Oxide when combined with Ozone (O3) produces light ;

NO+ O3 > NO2 + O2 + photonOzone is generated from pure oxygen through a high voltage discharge

The nitric oxide combines with the ozone forming the dioxide plus red light (0.6 to 3 micron) photons

The light is filtered to remove interference from other gases (CO, SO2, HC) and then measured by a photo multiplier tube (PM)

The greater the photon count the greater the NO concentration

NOx is measured by first passing some of the sample gas through an oven. This reduces all the NOx to NO which is then measured. The difference between the pre heated and unheated samples is the NOx concentration


Flame Ionization Detector (HC)

When hydrocarbon gases are burned within a non-ionized hydrogen/helium (40%/60%) flame free electrons and positive ions are produced

If an electrode is placed (100- 300 volts) within the flame a current will pass through the flame (~ 10 pA) in proportion to the number of carbon atoms present

The FID therefore measures the carbon concentration of the sample gas.

The measurement is usually reported as a volumetric ‘concentration’ of carbon atoms as a comparison with the concentration in either propane (C1) or hexane (C3) gases (eg ppm C1 or ppm Hexane etc)

HC FID concentration measurements can be affected by the HC mix, particularly if there are high levels of oxygenated compounds, such as (for example) alcohols, aldehydes and ketones present


Fourier Transform Infra-Red (NO, NO2, CO, CO2, short chain alcohols, hydrocarbons and aldehydes)

Relies on the principle that different chemical bonds absorb different energy levels when excited by IR light

FTIR uses an interferogram – a light source, split and then recombined to form interference fringes – to pass through the exhaust gas sample

The exhaust gas absorbs the interfered IR light according to the types of individual gases present each of which have their own unique characteristic absorption spectra.

By comparison of the sample spectra with a library of individual gas spectra the component gas concentrations can be identified

Horiba MEXA-4000FT


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Shaping the Future Engine Testing & Vehicle Emissions Testing