Search

Downdraft gasification is a potential method to produce biomass-based power suited for small-scaled power generation application. In the present study, a downdraft gasifier is used to gasify both raw and torrefied palm kernel shell (PKS). The properties of the palm kernel shells were characterised prior to gasification. Torrefaction of PKS was performed at the maximum temperature of 400 oC. Torrefied PKS shows lower moisture content by 4.8% as compared to raw kernel shell. Gasification of the feedstock showed that torrefied PKS produced higher amount of reactive syngas components, notably 16.4% CO and 9.25% H2 (by volume) than its raw counterpart. The total lower heating value of the syngas produced by torrefied PKS is 7.2 MJ/kg higher than that of raw PKS. Comparison of the temperature profiles within the gasifier for torrefied and raw PKS show distinct differences, with the temperature of the oxidation zone for raw and torrefied PKS being 1115oC and 1138oC at the equivalence ratio of 0.41 and 0.30, respectively. Although both feedstock show high potential for synthesis gas production, torrefied PKS produces syngas of higher LHV.

Synthesis gas (syngas) is a potential clean fuel for gas turbine. Experiments and numerical simulations were conducted to study the combustion characteristics of syngases in premixed swirl mode using a model gas turbine swirl burner. Four different types of syngases, covering low to high H 2 -content were tested. Experimental work was conducted to study the emission performance of lean swirl flame. Obtained results were used as validation targets for numerical simulation using flamelet generated manifold (FGM) and chemical equilibrium (CE) approaches. The former method shows better agreement with experimental result, hence FGM method was adopted to model flame structure and predict emission species in the reaction zones for different syngas types. Result shows that syngas with high concentration of H 2 produces lower peak flame temperature and height. Furthermore, high H 2 -rich syngas also produces low level of NO species in the reaction zone.

The share of renewable energy resources has been surging in the overall global energy mix, as energy consumption continues to rise due to the global population growth. Fears of the non-renewable resources depletion aside, fossil fuels have also been proven to be one of the main causes of global warming. Whilst in search of alternative fuels worldwide, biodiesel has emerged as one of the most viable candidates. This study aims to provide an overview on the feasibility of biodiesel to supplant fossil diesel through detailed analysis of feedstock readiness and economic viabilities of the implementations of three generations of biodiesel, i.e. edible, non-edible and algae-based biodiesel. In this paper, the global total production of biodiesel of 176 countries is calculated. At 85 billion litres, the first and second generation biodiesel production has the potential to exceed its current production by three times. The profitability of the biodiesel production relies heavily on the crude oil price. When the crude oil price peaked at 133.9 USD/bbl, 74% of the global potential biodiesel production can be made profitably, contributing 135.45 GW into the renewable energy mix. With business as usual scenario, edible oil biodiesel will remain to be the dominant category of feedstock. Nonetheless, 15 countries are able to replace portions of diesel consumption with second generation non-edible biodiesel, with two being able to entirely supplant fossil diesel with it The implementation of third generation algae-based biodiesel can save up to 93% of arable land. In all, biodiesel represents a great alternative to the unsustainable fossil diesel usage and contributes to the renewable energy mix.

In recent years, advances in numerical modelling of engines have led to the integration of 3-dimensional computational fluid dynamics with chemistry to calculate both the physical flow field and complex chemical reactions. However, it is only feasible to simulate the combustion chamber, but not the entire engine due to simulation runtime limitations. Onedimensional (1D) simulations of an entire engine are rapid yet comprehensive, but focus only on the applied thermodynamics with rudimentary global reaction chemistry. In this study, a compact combined biodiesel-diesel chemical kinetics reaction mechanism is integrated into the 1D modelling of a complete engine. Entire engine cycle from air intake to exhaust product is simulated using commercial software, AVL Boost. This allows for rapid system-level simulation which takes into account applied thermodynamics with complex chemical kinetics to account for combustion and pollutant formation. The integrated 1D-chemical kinetics model is successfully validated against experimental data with both the diesel and palm biodiesel fuel for key combustion parameters. The model would be able to simulate any dieselbiodiesel mixture of any blend levels and also biodiesel produced from different feedstock. This is due to the reaction mechanism comprising of n-Heptane, methyl butanoate and methyl crotonate which are the surrogate fuel models of straight chain hydrocarbon, saturated fatty acid methyl ester (FAME) and unsaturated FAME, respectively. Thus, CME, PME, and SME, are selected for blending due to their innate FAME proportions to represent the high, medium, and low saturated:unsaturated biodiesel, respectively. In all, through 100 simulated cases, this study demonstrated the feasibility of integrating chemical kinetics into 1D numerical model for a complete engine. Ultimately, the use of an integrated 1D-chemical kinetics model for engine simulations can greatly reduce optimisation time for emissions reduction.