Numerical Optimization of a Premixer for an Internal Combustion Engine using Producer Gas as a Fuel

Abstract

Gasification seems to be one of the sustainable green energy solutions to fulfill the current and future energy needs. For efficient utilization of producer gas on existing IC Engines, carburetor/premixer needs to be carefully designed and developed to achieve uniform mixing quality. A long radius nozzle type premixer has been designed for natural gas engine to be operated on producer gas as an alternate fuel. Different configurations of T – Type premixers with single air entry and twin air entry with different throat diameters and hole sizes are numerically analysed using ANSYS® CFX. Turbulence is modelled using RNG k - ε closure model. Mixer performance is compared in terms of constituents’ mass fraction, flow Uniformity Index (UI) and pressure penalty. Numerical analysis reveals that throat diameter, air entry type and air hole diameter governs mixing and pressure drop. Out of all configurations, twin air entry type premixer provides better mixing of producer gas and air. The optimized design of premixer shows that the absolute deviation in mass fraction of individual constituent lies in the range of ± 1.73% with respect to the actual mass fractions obtained. The average absolute deviation calculated is 1.37% with Uniformity Index 0.958 at the exit plane while the pressure drop across the premixer is 951 Pa.