Mohamad Shaiful Ashrul Ishak

Numerical Investigation of Combustion Performance Utilizing Envo-Diesel Blends

Alternative fuel and renewable energy is needed to fulfill the energy demand of the world. The use of envo-diesel fuels for power generation seems a viable solution for the problems of decreasing fossil-fuel reserves and environmental concerns. The use of envo-diesel in gas turbines would extend this application to power generation field. Envo-diesel is considered as better option because of its environmental friendly characteristics while giving almost the same functional properties like a fossil fuels. The gas turbine combustion performance that utilizes palm envo-diesel fuel is investigated. This study is to perform a detailed simulation of combustion and thermal flow behaviors inside the combustor. The simulations are conducted using the commercial Computational Fluid Dynamics (CFD) package software to determine the spray flames and combustion characteristics of commercial diesel fuel, envo-E5 and envo-E10. The diameter and temperature of the fuel droplets; and temperature contour, mass fraction of diesel and mass fraction of carbon dioxide (CO2) of the combustor were obtained for commercial diesel fuel, envo-E5 and envo-E10. Diesel fuel displayed higher rates of droplet evaporation compared to E5 and E10 with SMD differential about 30 to 40 μm while mass fraction for E5 and E10 slightly lower than conventional diesel.

Pengaruh Penyelitan Plat Orifis dalam Mengurangkan Emisi dari Pembakar

Penyelidikan telah dijalankan ke atas plat orifis pelbagai saiz yang dipasangkan pada keluaran pemusar udara sebuah pembakar berbahan api cecair yang berdiameter dalam 163 mm dan panjangnya 280 mm. Pembakar ini menggunakan kerosin sebagai bahan api. Terdapat dua saiz plat orifis yang setiap satunya berdiameter 25 mm dan 30 mm telah digunakan dengan pemusar udara aliran jejarian yang mempunyai sudut bilah 30°. Dalam ujikaji ini, penyelitan plat orifis ini akan menyebabkan peningkatan terhadap kehilangan tekanan di bahagian keluaran pemusar dan seterusnya meningkatkan aliran gelora yang akan menambah kadar percampuran bahan api dengan udara. Pemancit bahan api semburan paksi yang mempunyai dua lubang keluaran telah dipasangkan di bahagian belakang pemusar udara. Kadar alir bahan api menjadi parameter yang diubah dalam ujikaji yang dijalankan. Keputusan yang diperolehi menunjukkan dengan penyelitan plat orifis, emisi NO x berjaya dikurangkan sebanyak 50% bagi penyelitan plat orifis 25 mm, manakala CO sebanyak 5% dan CO 2 sebanyak 20% jika dibandingkan dengan kes tanpa penyelitan plat orifis. Kata kunci: Plat orifis; emisi NOx; pemusar udara; emisi CO; pemancit bahan api A liqued fuel burner system with different orifice plate sizes mounted at the exit plane of the radial air swirler outlet has been investigated using 163 mm inside diameter combustor of 280 mm length. All tests were conducted using kerosene as fuel. Two different orifice plates with diameter of 25 mm and 30 mm were used with a 30° radial air swirler vane angle. The purpose of orifice plate insertion was to create the swirler pressure loss at the swirler outlet so that the swirler outlet shear layer turbulence was maximized to assist in the mixing of fuel and air. Fuel was injected at the back plate of the swirler outlet using central fuel injector with dual fuel nozzles pointing axially outwards. The fuel flow rates were varied. The results show that orifice plate enhances better mixing and reduces NO x emmisions. NO x reduction of more than 50% was obtained using the 25 mm diameter orifice plate compared to the test condition without orifice plate. CO emissions were also reduced by 5%. CO 2 emission reduction of more than 20% was achieved for the same condition. Key words: Orifice plate; NOx emissions; air swirler; CO emissions; fuel atomiser