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

The Engine Test Cell Example – Passenger Car Full Transient, Low Inertia, Gaseous Emissions Rated Power 220kW at 4,500 rpm Rated Torque 467 Nm, Max Spd rpm Fuels: Petrol, Diesel, Bio Example – Heavy Duty Truck Full Transient, Low Inertia, Conditioned Air, Gas & Particulate Emissions Max Power 340kW at 1,500 rpm Maximum Torque 2165 Nm, Maximum Speed 3,500 rpm Fuels: Diesel, Biodiesel

The Engine Test Cell Example – Industrial/Marine Diesel Example – Single Cylinder Research (Optical) Engine

The Engine Test Cell Engine Dynamometer (Dyno) Load Absorbing and Measuring Machine Torque Arm Trunnion Bearings Rotor Stator Load Absorption via Electrical Power Generation AC or DC Power

The Engine Test Cell Eddy Current Dynamometer  Load Control via magnetic field flux  Loss plates need cooling  Torque reaction measured with load cell  Good for steady state testing

The Engine Test Cell 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

The Engine Test Cell Dynamometer Operating Envelopes (“Dyno Curves”)

The Engine Test Cell Dynamometer Operating Modes

The Engine Test Cell Vibration Isolation Electrical Power Absorption Seismic Mass

The Engine Test Cell Combustion Air Handling System Design Flow Rate 1000 m3/Hr Pressure Gain Max m3/Hr Pressure Max Flow 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 Electrical Power Absorption

The Engine Test Cell Electrical Power Absorption Combustion Air Handling 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

The Engine Test Cell Electrical Power Absorption Combustion Air Handling Fuel Supply and Return Fuel Conditioning & Mass Flow Measurement Fuel Mass Flow Measurement Gravimetric Fuel Mass MeterCoriolis Fuel Mass Meter

The Engine Test Cell Combustion Air Handling Engine Oil & Water Cooling (Shell & Tube Heat Exchangers) Raw Water Supply Cooling Towers, Fans Fuel Supply and Return Electrical Power Absorption Fuel Conditioning & Mass Flow Measurement Cooling Post

The Engine Test Cell Combustion Air Handling Exhaust Extraction and Emissions Measurement Engine Oil & Water Cooling (Shell & Tube Heat Exchangers) Raw Water Supply Cooling Towers, Fans Fuel Supply and Return Fuel Conditioning & Mass Flow Measurement

The Engine Test Cell Combustion Air Handling Exhaust Extraction and Emissions Measurement Engine Oil & Water Cooling (Shell & Tube Heat Exchangers) Raw Water Supply Cooling Towers, Fans Seismic Mass Fuel Supply and Return Electrical Power Absorption Fuel Conditioning & Mass Flow Measurement 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 J1349 Engine Power Test Code Spark Ignition and Compression Ignition Net Power Rating (Equivalent to ISO 1585)

Test Procedures - example SAE J1349 Net 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.

Test Procedures - example SAE J1349 Net 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

Test Procedures - example SAE J1349 Net 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. Reference Atmospheric Conditions

Test Procedures - example SAE J1349 Net 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. Reference Fuel Regular FuelMid GradePremium RON (+/- 0.5) MON (+/- 0.5) LHV (+/- 0.1) 43.3 MJ/kg 43.1 MJ/kg

Test Procedures - example SAE J1349 Net 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. Procedures Instrument 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 2019 US Federal (EPA) - Tier 2 Standards European Union (EU) – Euro 5 Standards, Euro 6 from 2014

EU Regulated Emissions

US Federal Regulated Emissions 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)

Vehicle Emissions Testing Non Legislative Emissions Measurement for Engine Development Purposes Measurement of Regulated Gaseous & Particulate Engine Emissions per Vehicle Measurement of Regulated Total Vehicle Hydrocarbon Emissions

Vehicle Emissions Testing 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.

Vehicle Emissions Testing Non Legislative Emissions Measurement for Engine Development Purposes Measurement of Regulated Gaseous & Particulate Engine Emissions per Vehicle Measurement of Regulated Total Vehicle Hydrocarbon Emissions

Regulated Gaseous & Particulate Engine Emissions General Principles  HC (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;

Legislative Emissions Measurement

Air dilution is with a Constant Volume Sampling System (CVS) The orifice flows sonic

CVS Sampling System

Test Cycles Japan Mode European NEDC (EDC & EUDC ) USA FTP 75

Test Cycles Worldwide 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

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

Particulate Size Measurement Two types of Measurement Techniques Electrical Mobility Particle Sensor Cascade Impactors Electrical Mobility Particle Sensor Measure 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 Impactor Measure 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

Vehicle Emissions Testing Non Legislative Emissions Measurement for Engine Development Purposes Measurement of Regulated Gaseous & Particulate Engine Emissions per Vehicle Measurement of Regulated Total Vehicle Hydrocarbon Emissions

Total Vehicle HC Emissions Variable Temperature SHED Atmospheric HC pollution is emitted from all parts of the vehicle Measurement 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

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Gas Measurement Principles Non Dispersive Infra Red (CO, CO 2 ) Black body infra- red radiation emitters Reference Inert Gas (N 2 ) Chopper Plate (10 Hz) Sample Gas Compensator Measurement cell with pure gas (CO or CO 2 ) 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 (O 3 ) produces light ; NO+ O 3 > NO 2 + O 2 + photon  Ozone 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 Gas Measurement Principles

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 ( 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 Gas Measurement Principles

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 Gas Measurement Principles