An optical fibre based exhaust gas sensor has been developed from low-cost mid-infrared components which is capable of detecting carbon dioxide (CO2) emissions from both diesel and petrol engines. The optical fibre sensor is not cross sensitive to other gaseous species in the exhaust such as water vapour (H2O), carbon monoxide (CO), oxides of nitrogen
(NOx) or oxides of sulphur (SOx). Initial tests of this sensor on a modern diesel engine are outlined in this paper.
This paper discusses the development of an optical fibre sensor suitable for the detection of gas emissions from motor vehicles based on mid-infrared spectroscopy. Initial measurements are presented for carbon dioxide emissions from a petrol engine using low-cost mid-infrared components, and a practical detection system, which could be fitted to a vehicle, is outlined.
In order to meet increasingly stringent emission control laws it is necessary to develop a sensor that can accurately monitor the level of pollutants entering the atmosphere from land transport vehicles. These pollutants are generally a mixture of hot gases and particulates. An optical fibre sensor is particularly well suited to this task. Due to it's small size and weight it is minimally invasive making it suitable for insertion into the vehicle's exhaust system. Optical fibres are immune from poisoning by the analyte gases, although they do require shielding from airborne particulates. As they do not transmit electricity they are also highly safe and furthermore they are immune from electromagnetic interference. To detect the presence of the gases it is proposed to use an optical absorption technique. The majority of gases of industrial and environmental importance have their fundamental absorption line in the mid-infrared region of the electromagnetic spectrum, with weaker overtones in the near infrared. Due to the greater availability of components, optimised for communications, most optical fibre gas sensing has taken place in the near-infrared region of the spectrum. In this paper mid-infrared optical fibre gas sensing techniques are investigated and the results of the investigation are presented. Due to the inhomogeneous state of the gas flow it is necessary to measure temperature especially just upstream of the after-treatment section where this can rise to as high as 650oC with large temporal gradients. Measurements of temperature of hot gases from a full size test engine using an optical fibre probe based on fluorescence decay time measurements are also presented.
In order to satisfy increasingly stringent automotive emission control laws, it is necessary to develop sensors that are capable of quantifying exactly the pollutants entering the atmosphere. The development of a mid-infrared optical fibre based sensor suitable for the detection of automotive emissions is discussed in this paper. Mid-infrared spectroscopy is deemed suitable for the task as the fundamental absorption lines of the majority of the pollutant exhaust gases are in the mid-infrared region of the spectrum. This paper focuses on the monitoring of carbon dioxide gas as it has significant absorption in the mid-infrared.
An optical fiber sensing system is investigated for measurement of exhaust emissions from an engine. This paper discusses the component infrastructure to conduct this task in the mid-infrared region and a sensing fiber and test system are proposed.