Organised by the IOP Dielectrics and Electrostatics Group
The diesel engine has the highest efficiency among all the engines known today and therefore is popular in most industrial and marine applications. However, the exhaust emitted by these engines contains several harmful pollutants and contributes to more than 40 % of man-made pollution. The major pollutants in diesel engine exhaust are NOx, SOx, CO, CO2, VoCs and particulate matter (PM). There is a long list of deleterious environmental and human health effects of these pollutants. The environmental effects include the formation of smog, acid rain, greenhouse effect and corrosion, to name a few. When it comes to impact on human health, it is well documented that these pollutants cause emphysema, have carcinogenic properties and damage the functioning of several vital organs in the human body, primarily the heart and lungs. The increasingly stringent restrictions imposed on the emission of harmful gases from industrial/automobile/stationary diesel engine exhaust around the world have led to the development of a number of new technologies to address this issue. The Non-thermal plasma (NTP) based cleaning appears to be one such promising technology for treating the gaseous pollutants.
Non-thermal plasma (NTP) can be used successfully for the abatement of SOx, NOx, PM and VOCs in exhaust gases emitted by diesel engines fuelled by diesel or biodiesel. This is achieved through the introduction of NTP inside the exhaust gases. It is composed of free electrons, ions, radicals, atoms and molecules in various states of excitation, which have a tendency to remain electrically neutral over large length scales. In NTP, the electrons have a kinetic energy higher than the energy corresponding to the random motion of the background gas molecules in the range (10,000-100,000) K, which is 2-3 orders of magnitude greater than the background gas. NTP can be generated using corona discharges, RF discharges, microwave discharges, electron beam discharges, dielectric barrier discharges and a combination of microwave and electron beam. Recent studies conducted at Brunel University London, have demonstrated that microwave generated non-thermal plasma in a pilot-scale system, can successfully remove 99% SOx, 98% NOx and >90% PM (<1 µm) from diesel engine exhaust gas.
Lightening and Climate
The World Meteorological Organization recently declared lightning ﬂashes to be an Essential Climate Variable. This declaration elevates lightning ﬂashes to a climate quantity that is currently mainly assessed by lightning imagers on satellites and ground based lightning detection networks. Lightning ﬂashes are generated by thunderstorms which develop when hot and humid air leads to atmospheric instability and upper atmosphere dynamics enables deep convection to occur. The majority of all lightning ﬂashes occur in the continental tropical belt around the globe. The primary lightning climatology follows solar insolation with a longitudinal migration that corresponds to a diurnal variation and a latitudinal migration that corresponds to an annual variation. As a result, lightning ﬂashes are a diagnostic tool for key driving processes of climate variability and contribute to positive feedback. Lightning flashes cause a globally resonant electromagnetic wave field that can also be used as a diagnostic tool for lightning and climate. Yet, Maxwell’s equations are not designed to include thermodynamic variables such that the connection to global climate change is normally made through thundercloud microphysics and the electromagnetic energy of thunderclouds or lightning flashes.
Chair: Nadarajah Manivannan, Brunel University, UK