Mitigating Carbon Dioxide Emissions in Diesel Engines through the Application of Physical Adsorbents

The world is targeting zero-emission standards by promoting flexi-fuel-based vehicles. In the automotive industry, IC engine-powered vehicle has a good market. Either IC or flexi-fuel engines are considered the safest mode of transport, one tedious problem needs to be addressed is their toxic exhaust emissions from those engines. However, there are many aftertreatment systems available to control HC, CO₂, NOx, and PM emissions. To control CO₂ emissions there is no aftertreatment system available. Physical adsorbents such as activated carbon and zeolite are going to be used in this work to reduce emissions from exhaust gases. Zeolite has a greater affinity toward NOx emission, and activated carbon has greater potential to capture HC and carbon dioxide emissions. Initially computational studies were carried out to evaluate back pressure developed in adsorbent chamber. Analysis was carried out by varying conical length of the adsorbent chamber (68 mm, 75 mm, and 85 mm) at various exhaust temperatures (220°C, 300°C, and 350°C). Computational results conveyed that the adsorbent chamber with 85 mm shows acceptable pressure drop. Experiments were conducted with varying quantities of zeolite and activated carbon in a twin-cylinder naturally aspirated diesel engine. Initially, adsorbent quantities were varied at 550 g and 1100 g and tested at various load conditions (0%, 25%, 50%, 75%, and 100%). Then the experiments were conducted by filling the combinations of the adsorbents and the results were plotted. It is observed that a maximum of around 70% reduction in HC emission is achieved while filling 1100 g of activated carbon. On the other hand, while filling zeolite at 1100 g maximum reduction of 85% NOx is observed while operating the engine at higher load conditions. Finally, by filling combinations of adsorbents the CO₂ emissions show higher reduction efficiency of around 85% at higher load conditions