Pegasor Oy


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Rostedt A.,Tampere University of Technology | Ntziachristos L.D.,Tampere University of Technology | Simonen P.,Tampere University of Technology | Ronkko T.,Tampere University of Technology | And 4 more authors.
SAE International Journal of Engines | Year: 2017

In this article we present a design of a new miniaturized sensor with the capacity to measure exhaust particle concentrations on board vehicles and engines. The sensor is characterized by ultra-fast response time, high sensitivity, and a wide dynamic range. In addition, the physical dimensions of the sensor enable its placement along the exhaust line. The concentration response and temporal performance of a prototype sensor are discussed and characterized with aerosol laboratory test measurements. The sensor performance was also tested with actual engine exhaust in both chassis and engine dynamometer measurements. These measurements demonstrate that the sensor has the potential to meet and even exceed any requirements around the world in terms of on-board diagnostic (OBD) sensitivity and frequency of monitoring. Further to potential OBD applications, this has the capacity to be used as an engine and combustion diagnostics sensor, for example to detect misfiring, cylinder combustion variability, exhaust gas recirculation flowrate, etc. © 2017 SAE International.

Jarvinen A.,Tampere University of Technology | Kuuluvainen H.,Tampere University of Technology | Niemi J.V.,Helsinki Region Environmental Services Authority HSY | Niemi J.V.,University of Helsinki | And 7 more authors.
Urban Climate | Year: 2015

Urban air contains considerable amounts of harmful gaseous substances and aerosol particles. In this study, a recently introduced diffusion charger based PPS-M particle sensor (Pegasor Oy, Tampere, Finland) was evaluated for outdoor air quality measurements in urban environment. The PPS-M particle sensor was used in two stationary air quality measurement stations, one located in the roadside environment and the other in residential area, and in a mobile laboratory. The sampling of urban aerosol to the PPS-M sensor was performed without any pre-conditioning of aerosol. The sensor response to PM2.5 varied between the measurements, being between 7 and 30fA/(μg/m3) depending on the aerosol source. The highest PM2.5 response was observed in the roadside study for exhaust particles while the lowest PM2.5 response was observed for large long range transported aerosol particles having relatively large mean particle size. The sensor signal was found to produce very linear response, with only minimal deviation, to the lung deposited particle surface area concentration (from 4.5 to 6fA/(μm2/cm3)) and to the condensation sink of urban air particles (from 1.0×104 to 1.2×104 fAcm3). The sensor response to particle number concentration was defined to be 0.0044fA/(1/cm3) in roadside environment. In this environment, the signal was found to correlate also with NO and NO2 concentrations of roadside air due to the same origin of particulate and gaseous pollutants. Similar correlation between NOx and the PPS-M signal was not observed in residential area. © 2014.

Ntziachristos L.,Aristotle University of Thessaloniki | Amanatidis S.,Aristotle University of Thessaloniki | Samaras Z.,Aristotle University of Thessaloniki | Janka K.,Pegasor Oy | Tikkanen J.,Pegasor Oy
SAE International Journal of Fuels and Lubricants | Year: 2013

The Pegasor Particle Sensor (PPS) is a small and lightweight sensor that can be used directly in raw exhaust to provide the mass and number concentration of exhaust aerosol. Its operation principle is based on the electrical charging of exhaust aerosol and determination of particle concentration by measuring the charge accumulated on the particles. In this paper we have applied the PPS in a variety of vehicle exhaust configurations to evaluate its performance characteristics. First, the output signal of the instrument was calibrated with diesel exhaust to deliver either the mass or the number concentration of exhaust aerosol. Linear response with the soot mass concentration measured by a Photo Acoustic Soot Sensor and number concentration measured by an Electrical Low Pressure Impactor was established. Based on this calibration, the instrument was then used to measure particle concentrations at levels produced by a gasoline direct injection vehicle and diesel exhaust filtered by particle filters of variable efficiency. Hence, the complete range of concentrations and particle characteristics typically encountered in automotive exhaust has been examined. The results show that the PPS signal can provide a repeatable measurement of aerosol concentration in the exhaust of current vehicles, offering a very good correlation both to the mass and number of particles, as measured by existing techniques. Copyright © 2013 SAE International.

Ntziachristos L.,Aristotle University of Thessaloniki | Fragkiadoulakis P.,Aristotle University of Thessaloniki | Samaras Z.,Aristotle University of Thessaloniki | Janka K.,Pegasor Oy | Tikkanen J.,Pegasor Oy
SAE Technical Papers | Year: 2011

Efforts to develop a sensor for on-board diagnostics (OBD) of diesel vehicles are intensive as diesel particulate filters (DPFs) have become widespread around the world. This study presents a novel sensor that has been successfully tested for OBD diagnosis of damaged DPFs. The sensor is based on the "escaping current" technique. Based on this, a sample of exhaust gas is charged by a corona-ionized flow and is pumped by an ejector dilutor built in the sensor's construction. While the majority of ions return to the grounded sensor's body, a small quantity is lost with the charged particles exiting the sensor. This "escaping current" is a measurement of the particle concentration in the exhaust gas. Such a sensor has been developed and tested in real-exhaust of a diesel car and a diesel engine. The sensor provides high resolution (1 Hz, 0.3 s response time) and high sensitivity superseding OBD requirements. The sensor was used on an engine to monitor the efficiency of damaged DPFs. The signal was found to perform similar to the smokemeter, a widespread instrument used for routine testing in automotive laboratories. The sensor was then installed in the exhaust of a vehicle to test the DPF efficiency of a well operating and a damaged DPF over a transient test. The sensor was found to be sensitive enough to clearly detect a defected from a well-operating particle filter even at levels as low as 6 mg km-1. This study demonstrates that a soot sensor based on the escaping current technique has the potential to be used for OBD and DPF control on forthcoming light duty and heavy duty diesel vehicles. Copyright © 2011 SAE International.

Amanatidis S.,Aristotle University of Thessaloniki | Ntziachristos L.,Aristotle University of Thessaloniki | Samaras Z.,Aristotle University of Thessaloniki | Janka K.,Pegasor Oy | Tikkanen J.,Pegasor Oy
SAE Technical Papers | Year: 2013

The Pegasor Particle Sensor (PPS) has been earlier presented by Ntziachristos et al. (SAE Paper 2011-01-0626) as a novel small and robust instrument that can be directly installed in the exhaust line to measure exhaust particles without any dilution. The instrument is based on the electrical detection of aerosol. It is increasingly being used to measure exhaust particles from engines and vehicles with different exhaust configurations. In this study, a number of tests have been conducted using two sensors in parallel, one directly installed in the tailpipe and one installed in the CVS, side by side to the PM sampling filter. Aim of the study was to make recommendations on the proper use of the sensor and to check how the sensor signal compares to particulate mass, soot concentration, and particle number. A first finding is that external heating has to be provided to the sensor to avoid condensation. Second, very good linearity of the sensor signal is established for all three particle concentrations examined. The only exception was PM at very low concentrations, where positive adsorption artifacts determine the mass collected on the filter. Also, the original calibration provided with the sensor offers a satisfactory match with the absolute level of mass and number measured with other instruments. Improving this requires either specific calibration of the sensor for a particular emission source, or, at least, knowledge of the particle size distribution. Copyright © 2013 SAE International.

Amanatidis S.,Aristotle University of Thessaloniki | Ntziachristos L.,Aristotle University of Thessaloniki | Samaras Z.,Aristotle University of Thessaloniki | Kouridis C.,EMISIA SA | And 2 more authors.
SAE Technical Papers | Year: 2014

The effect of "Start & Stop" and "Gear Shift Indicator" - two widespread fuel saving technologies - on fuel consumption and particle emissions of a Euro 5 passenger car is evaluated in this paper. The vehicle was subjected to a series of different driving cycles, including the current (NEDC) and future (WLTC) cycles implemented in the European type approval procedure at cold and hot start condition and particle number was measured with an AVL Particle Counter. In addition, we have utilized two Pegasor Particle Sensor units positioned in different locations along the sampling line to assess the impact of the sampling location on the particle characteristics measured during highly transient events. The results showed that the particle number emission levels over the WLTC were comparable to the NEDC ones, whereas NOx emissions were more than twofold higher. Both fuel saving technologies can lead to reduced fuel consumption and, subsequently CO 2 emissions, in the order of 5%. However, their impact on particle emissions was not straightforward, as the impact of the DPF loading was found much more significant than the effect of these technologies. However, in several occasions, the frequent start and stops of the engine actually led to an increase in particle emissions over the baseline. On the other hand, the reduced engine speed imposed when the gear shift indicator was respected generally led to lower particle emissions. Transient impacts on particle emissions such as those resulted by the fuel saving technologies studied can be much better monitored with raw exhaust sampling than following the type approval sampling procedure. This recommendation tends to be forgotten in regular research works. Copyright © 2014 SAE International.

Rostedt A.,Tampere University of Technology | Arffman A.,Tampere University of Technology | Janka K.,Pegasor Oy | Yli-Ojanpera J.,Tampere University of Technology | Keskinen J.,Tampere University of Technology
Aerosol Science and Technology | Year: 2014

The Pegasor PPS-M sensor is an electrical aerosol sensor based on diffusion charging and current measurement without particle collection. In this study, the role and effect of each component in the instrument is discussed shortly and the results from a thorough calibration measurements are presented. A comprehensive response model for the operation of the PPS-M sensor was developed based on the calibration results and computational fluid dynamics (CFD) modeling results. The obtained response model, covering the effects of the particle charger, the mobility analyzer, and both diffusion and inertial losses, was tested in the laboratory measurements with polydisperse test aerosols, where a good correlation between the model and the measured results was found.Copyright 2014 American Association for Aerosol Research © 2014 American Association for Aerosol Research.

Pegasor Oy | Date: 2011-02-24

A new apparatus for monitoring fine particle concentration in an exhaust system of a combustion engine has a part that extends into the exhaust system, and a housing that includes structure that attaches and seals the apparatus to the exhaust system through a single opening in a wall of the exhaust system. A gas inlet in the housing provides a measurement flow into a particle measurement sensor inside the housing. At least a fraction of the particles entering the particle measurement sensor are charged, and at least a fraction of the current carried by the charged particles are detected. A gas outlet in the housing carries the measurement flow away from the particle measurement sensor. The structure that attaches the apparatus to the exhaust system has one electrical connector that provides power to the sensor, and another electrical connector that transmits the electrical signal created by the sensor.

Pegasor Oy | Date: 2011-12-28

The present invention relates to an apparatus (1) for monitoring particles in a channel (11) or a space comprising aerosol and to an ion trap arrangement in the apparatus. The apparatus (1) comprises an ejector (24), gas supply (6, 16, 18, 19) arranged to feed an essentially particle free ionized gas flow (C) to the ejector (24), a sample-inlet arrangement (2) arranged to provide a sample aerosol flow (A) from the channel (11) into the ejector (24) by means of suction provided by the gas supply (6, 16, 18, 19) and the ejector (24) for charging at least a fraction of the particles of the sample aerosol flow (A), and an ion trap (12) extending at least partly into ejector (24) for removing ions not attached to the particles. According to the invention the ion trap (12) is a provided as a metal trap wire.

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