Browsing Engineering and Informatics by Author "Pimenidou, Panagiota"
Dolomite study for in situ CO 2 capture for chemical looping reformingPimenidou, Panagiota; Dupont, V. (2015)The non-isothermal kinetic and thermal behaviour of a naturally formed dolomite in conditions that approach in situ CO2 capture in chemical looping reforming, were investigated. The performance of this dolomite was studied at micro-scale in ‘dry’ conditions, as well as at macro-scale in ‘dry’ and ‘wet’ conditions to investigate the effects of scale (3 mg, 2.5 g), partial pressures of CO2 (<15 kPa) and steam, and deactivation upon limited cycling. The carbonation and calcination kinetics were modelled using an improved iterative Coats–Redfern method. Increasing CO2 partial pressures on the ‘dry’ macroscale exacerbated the experimental carbonation conversions in an inversely proportional trend when compared with those at micro-scale. The presence of steam had a positive effect on CO2 chemisorption. Steam had a negligible influence on the calcination activation energies. The activation energies of carbonation were increased for the experiments at the highest CO2 partial pressures under wet conditions.
Performance and emissions study of diesel and waste biodiesel blends with nanosized CZA2 of high oxygen storage capacityPimenidou, Panagiota; Shanmugapriya, N.; Shah, N. (2019)In this work, the effect of the nanosized CZA2 (cerium-zirconium-aluminium) on the performance and emissions in a two- cylinder indirect injection (IDI) diesel engine, was studied. CZA2 was dispersed in diesel (D100) and waste cooking oil and tallow origin biodiesel-diesel blends (B10, B20, B30) and tested at different engine loads and constant speed. The nanocatalyst (CZA2) increased the brake specific fuel consumption (BSFC) and decreased the brake thermal efficiency (BTE, %) of all tested fuels, at all loads, except B20 at the lowest load. CZA2 reduced nitrogen oxides (NOx) from D100 at low and high engine loads, as well as carbon monoxide (CO) and unburned hydrocarbons (HC) at medium and high tested loads. The dispersion of CZA2 promoted the combustion of the biodiesel blends by almost eliminating HC while reducing NOx and CO emissions at various loads. Thermogravimetric analysis (TGA) coupled with Attenuated Total Reflectance- Fourier Transform Infrared (ATR-FTIR) spectroscopy revealed that the addition of CZA2 in diesel and biodiesel under pyrolysis and oxidation conditions resulted in the presence of saturated species like ketones and final oxidation products such as CO2, supporting their improved combustion and emissions’ reduction in the engine tests.