RDE PEMS Real Driving Emissions Portable Emissions Measurement Systems

Description of Axion

What is the accuracy, and do you have any laboratory correlation data? How is Axion calibrated?

Axion is typically calibrated using a locally obtained “smog check” calibration gas mix (propane, CO, CO2, NO). Data from several laboratories using various vehicles and fuels shows that when Axion is operated simultaneously with the laboratory system, the difference is typically less than 10% for aggregate mass NOx and CO2. The accuracy of HC and CO measurements depends on the fuel used and on the emission levels. The accuracy of PM measurement has not been quantified at this point. Data from the EPA Laboratory in Ann Arbor, Michigan also shows that the difference between the portable system and two laboratory systems (model and bag sampling) was comparable to the differences between the two laboratory systems.Laboratory Comparison information is available upon request.

What are the power requirements?

Axion typically is powered by a 12V DC vehicle electrical system, using a cigarette lighter outlet, back up batteries, or direct connection to the vehicle battery. The power consumption is 6-9 Amps at 13.8VDC. 24VDC and 240 or 110 VAC converters are available.

What is the portability, size, and weight of your system?

Axion R/S weighs approximately 35 pounds and can by transported as luggage on commercial flights.
Axion GO weighs approximately 18 pounds and is also easily transported on commercial flights. Its size even allows for stowage under the airplane seat.

How long does it take to install your equipment?

Typical swap times range from 5 to 30 minutes, measured as a complete removal of Axion from one vehicle and a subsequent complete installation of Axion on another vehicle. You can refer to our video on Global MRV entitled “Truck, Car, Scooter Setup” for a visual reference of Axion PEMS flexibility.
The complete system comes in two weatherproof plastic cases. One contains the monitoring system itself and the other contains sample inlet and exhaust lines, tie-down straps, AC adapter, power and data cables, various ECU diagnostic link connectors, sensor array, calibration gas pressure regulator and other parts.

How long does it take to install your equipment?

I have seen some other types of PEMS equipment. Does your system require drilling holes, or modifying frames of the vehicles?

Axion PEMS typically do not require any modifications to the tested vehicle. The only exceptions are installing a sampling port upstream of an exhaust after-treatment device for before and after testing.

What types of vehicles, engines and/or applications are there for Axion products?

Axion PEMS can be used with any internal combustion engine and fuel. Cars, light trucks, vans, shuttles, school, transit, and coach buses, box trucks, over-the-road tractor-trailers powered by gasoline, CNG, diesel fuel, and biodiesel are tested on a routine basis. Off-road equipment that Axion PEMS have successfully tested include yard tractors, ATV’s, scooters, motorcycles, recreational boats, small aircraft (ground use only), locomotives, passenger ferryboats, construction equipment and electric generators.

What type of test cycles or methods can be employed?

Axion products are designed to measure emissions during the actual use of the vehicle or equipment in its regular daily operation. It is intrinsically safe and has been used on shuttle, school and transit buses, all manner of construction vehicles, lawn equipment, motorcycles, and scooters during their regular operation with passengers on board. If repeatable testing cycles need to be followed, Global MRV personnel can design a specific and proprietary Driver’s Aid software, which allows for the vehicle to be driven on a test track or other suitable roadway according to prescribed driving cycles, in a manner similar to operation on a chassis dynamometer.

How is flow measurement accomplished?

Exhaust flow is indirectly measured using engine operation parameters, known engine and fuel properties, and exhaust gas concentrations. This technique has been patented and successfully validated by repeated laboratory comparisons. Engine operation parameters can be acquired through the available Engine Control Unit diagnostic port for J1939, J1708, and OBDII protocols or by an array of sensors temporarily, non-intrusively, and passively attached to the engine.

What type of pollutants are measured, and what are the detection methods used?

Axion measures O2, HC, CO, CO2, NOx, and PM on a second-by-second basis. Other third party analytical equipment (i.e. FID, PID, electrochemical cells) can be added if desired.

HC, CO, CO2 using non-dispersive infrared (NDIR). The accuracy of the HC measurement depends on type of fuel used.
NOx measured as NO using electrochemical cell. On most vehicles, NOx can be inferred from NO. On diesel engines with CRT traps, NO, CO2, and NOx can be inferred by simultaneous measurement of NO before and after the trap.
PM is measured using light scattering, with measurement range from ambient levels to low double digit opacity levels.

What type of configurations of Axions are available?

Axion is applicable to both Heavy Duty Diesel and Light Duty Vehicles, and is a modular design. This configuration allows for relatively easy future upgrades.

Data Usage and Applications

How is your data formatted?

The data is available in ASCII text, comma-delimited format, but can be supplied in any user-defined format on demand.

PEMS data collected to ensure thorough test?

PEMS, when desired, can collect GPS data, ambient temperature, humidity, barometric pressure, and other relevant data…making it data powerful information with PEMS.

Can you provide information in grams per Brake/Horsepower hour?

When desired, engine power output can be estimated based on ECU torque readings and/or using the fuel consumption and engine rpm data, and the manufacturer’s brake-specific fuel consumption charts. All measured pollutants can then be calculated on a brake-specific basis, and additional calculations, such as “do not exceed” emissions (a 30-sec. average during the operation in a predetermined range of engine rpm and torque), can be performed on the fly as necessary.

Can the customer custom-tailor the data to be collected?

The user can define the beginning and end of different test segments, as well as enter user-defined flags (i.e. encountering a certain traffic condition). Total time, distance, fuel consumption, and emissions are calculated for each defined test segment.

What type of data do Axion systems collect?

Some or all of the following parameters are captured on a second-by-second basis: road speed, engine rpm, intake air pressure (turbo boost or MAP), throttle position, engine reported load, intake air temperature, concentrations of the measured pollutants, exhaust flow, air fuel ratio, fuel consumption, and mass of the measured pollutants.

Does GLOBALMRV ever share any of its’ raw emissions data with customers?

The data collected varies, depending on the application, and is tailored toward the testing needs of individual customers. Data is never, ever shared with other customers without prior written knowledge from the source client.

What types of data applications have been attempted with your system?

In order to quantify emission reduction associated with a particular measure (e.g. switch to an alternative fuel, installation of an exhaust after-treatment device, traffic pattern optimization), real-world emissions from the relevant fleet need to be determined. It is well understood that the emission variability among individual vehicles, and within each vehicle, can be substantial. Substantial errors in emission reduction estimates can thus result from selecting too small or not representative sample of vehicles. Also, chassis and engine dynamometer testing conditions are not representative of actual operation. Therefore, each Axion PEMS is designed to test a large number of vehicles during their actual use. As long as the vehicles tested and the operating conditions during the tests are representative of the fleet, the fleet emissions can then be easily calculated for virtually any fleet without the use of mathematical models.
Reports and publications from several projects aimed at quantifying emission reductions are available upon request.

Axion Specifications for Analyzers, Gas Benches, and Sample Lines

PEMS, by Global MRV, sampling handling system?

PEMS Portable Emissions Measurement System, by Global MRV, sample heating system is relatively simple. We use unheated, Teflon-lined exhaust sample hoses. Water is removed before the instrument intake, and filter the sample being sent to the gas analyzers. The probe is designed to sample perpendicular to the stream, avoiding larger particulates.

PEMS, by Global MRV, sample flow rate for gas analyzers: (1LPM/CO/CO2/HC/NOx/O2)?

PEMS , Portable Emissions Measurement System , or On-Board Emissions Monitor Equipment equipment produced by Global MRV, Inc. have 5 LPM for each the gas analyzer path. One (1) LPM goes through the NDIR and chemical sensors while the other four (4) LPM travels through the bypass of the PEMS. This maintains the proper back pressure for accuracy and precision. Four (4) LPM travels through the PM device with a small amount being pulled off for optical cleaning withing the portable emission measurement system.
Pems devices by global MRV utilize Two gas analyzers for the following reasons:

To increase pems accuracy.
To allow for periodic ambient air calibration of each portable emissions measurement system gas analyzer without interrupting emissions data collection.
To provide quality control for pems.

PEMS, by Global MRV, operate at what wavelength for hydrocarbon (HC) measurement?

PEMS, Portable Emissions Measurement System, or On-Board Emissions Monitor equipment manufactured by Global MRV, operate within around 3.4 micrometers in wavelength to measure hydrocarbons.
The exact center wavelength and bandwidth for Global MRV PEMS, Portable Emissions Measurement System, or On-Board Emissions Monitor equipment are company confidential.

PEMS, by Global MRV, can measure total HC?

PEMS, Portable Emissions Measurement System, or On-Board Emissions Monitor equipment by Global MRV total hydrocarbons (HC) are measured using IR optimized for hexane, and estimating total HC.
PEMS HC is not defended for compression ignition fuels as they are not measured well by this spectrum, and as we do not heat the sample lines, which allows heavier HC to condense out. Having said this, total HC for diesel engines are relatively low and not usually of great interest.
Speciated hydrocarbons, allowing for the identification of low concentrations of toxic HC is useful data, but it is not supported yet by PEMS with safe, non-hazardous, portable techniques.

PEMS, by Global MRV, is impacted by the type of fuel used, how?

PEMS, Portable Emissions Measurement System, or On-Board Emissions Monitor systems created by Global MRV, Inc. are not impacted by the type of fuel used.
PEMS should always be extremely flexible in with all types of fuels.
PEMS are called Portable Emissions Measurement System devices. Portable should always be the operative word. Easy to move by one person, without the need for forklifts or cranes or pulleys.
PEMS devices by Global MRV are the only On-Board Emissions Monitor verified by the USEPA using the ETV third party Battelle.

Are the CO, HC, CO2 analyzers are based on non-dispersive infrared (NDIR) principle?

Yes, these analyzers are based on the NDIR principle.

What are the detailed specifications of analyzers (linearity, noise, repeatability, drift, response, etc.)?

We have tested against several respected laboratories, using common chassis cycles, and can provide these laboratory comparison documents upon request.

What are the gas analyzer subsystem measurement specifications?

See the following chart:

	Tier I	Tier II
Instrument Reliability	40 – 60 %	85 – 98 %
Weight	35.4kg (78lbs)	≤18.8kg (41.5lbs)* (Ergol, 1990)
Gas Requirements	Hydrogen	None
Voltage Requirements	12VDC	12VDC
Amp Requirements (Warm-Up)	70A	5A
Amp Requirements (Steady)	30A	9A
Ambient Operating Temps.	0°C to 40°C	0°C to 50°C (non-condensing)
Storage Temps.	-10°C to 60°C	-20°C to 55°C
Sample Flow Rate	8LPM	4LPM
Data Rate	.833 to 4Hz	1Hz
Warm-Up Time	60 minutes at 20°C	≤45 minutes
Dimensions (cm)	36h x 43w x 55d	22h x 55w x 42d
Space Required (cm3)	85000 cm3	51000 cm3
Cost	Starting at $150,000	Starting at $59,000
Level of Complexity	High	Low
Operates In-situ (Heavy Duty)	Some	All
Operates In-situ (Light Duty)	Some	All
Operates In-situ (Motorcycle)	No	All
Operates In-situ (Sm. Engine)	No	All
Additional Vehicles Required	Yes	No

Measurement Accuracy Comparisons
	Product	CO	CO2	NO	NO2	HC
Range	Tier I	0-8%	0-20%	0-3,000 0-900 0-300	0-500 ppm 0-300 ppm 0-100 ppm	0-10,000 ppm
	Tier II	0-10%	0-16%	0-4000 ppm		0-4000ppm
Resolution	Tier I	10ppm	.01%	.01 ppm	0.1 ppm	1 ppm
	Tier II	.001vol.%	0.01vol.%	1ppm		1 ppm
Accuracy	Tier I	±3% or ±50 ppm	±3% or ±0.1%	±2% pt or ±2% meas	±2% pt or ±2% meas	±2% rdg or ±25 ppm
	Tier II	±3% or ±0.02% abs	±3% or ±0.3%	±4% or ±25 ppm		±3%rel or ±8ppm
Repeatability	Tier I	±2% or ±20 ppm	±2% or ±0.05%	1% pt or ±1% meas	±1% pt or ±1% meas	±1% rdg or ±10 ppm
	Tier II	±2% or ±0.2%abs.	±2% or ±0.1% abs.	±3% rel. or ±20 ppm		±2% rdg or ±6 ppm
Noise	Tier I	±20 ppm	±0.02%	±1% max	±1% max	±10 ppm
	Tier II	0.01%abs. or 0.8% rel.	0.1%abs. or 0.8%rel	10 ppm abs. or 1% rel.		0.8% rel or ±4ppm
Response Time	Tier I	T90<3 sec	T90<3 sec	T90<2 sec	T90<2 sec	T90<2sec
	Tier II	T90≤3sec	T90≤3sec	T90≤5sec		T90≤3sec
Flow Rate	Tier I	2 LPM	2LPM	3LPM	3LPM	2LPM
	Tier II	1LPM	1LPM	1LPM		1LPM
Data Rate	Tier I	0.833 Hz	0.833 Hz	1 Hz	1 Hz	up to 4 Hz
	Tier II	1 Hz	1 Hz	1 Hz		1 Hz