Ahmad Jais Alimin

Lean NOx trap study on a light-duty diesel engine using fast-response emission analysers

Abstract Storage and regeneration events have been studied using fast-response emission analysers (∼10 ms) for a lean NO x trap (LNT) fitted to a light-duty diesel engine. Tests were conducted at both low and high exhaust temperatures for various storage and purging periods. The use of fast-response analysers has provided detailed information during the short regeneration periods and as combustion switched between rich and lean operating modes. It has also enabled quantification of the storage, reduction, and overall conversion efficiencies, as well as the instantaneous trapping efficiency. With exhaust temperatures of 250 °C, storage efficiency was low (∼30 per cent). During purging, two distinct NO spikes (breakthroughs) were measured downstream of the LNT at the beginning and end of regeneration. For this LNT, the primary reducing mechanism is CO reacting with NO, but CO reacting with ceria and/or water, the water—gas shift reaction, is suspected. With exhaust temperatures of 400 °C, storage efficiencies were high (∼80–90 per cent), except for the long-storage/short-purge case when the trap was near saturation. NO x breakthrough during enrichment depended on storage and purge periods and the availability of catalyst sites. NO2 breakthrough was also observed at the end of regeneration as the combustion switched to lean operation. Generally, for the high-temperature case on this LNT, the primary reducing mechanism is CO reacting with NO2.

The Comparison of Preheat Fuel Characteristics of Biodiesel and Straight Vegetable Oil

Biodiesel is an alternative fuel derived from varies sources of vegetable oils, animal fat, or waste frying oil to give the corresponding fatty acid methyl ester. The properties of alternative fuel of CPO biodiesel and SVO biodiesel have been investigated at different temperature. The biodiesel was blended up palm oil blending ratio from 515vol% (B5B15) and straight vegetable oil ratio from 515vol% (S5S15). The properties were tested at 27.5°C, 40°C, 50°C and 60°C with observed the changes of the density, kinematic viscosity, flash point, water contents, and acid value. In this study, properties of CPO biodiesel were found to have a higher value and diesel fuel under all ambient temperature. Under all ambient temperature, preheating CPO fuel increased value of density, kinematic viscosity, water contents, and acid value than SVO biodiesel.

Predicting the Performance and Emissions Characteristics of a Medium Duty Engine Retrofitted with Compressed Natural Gas System Using 1-Dimensional Software

The rise of crude oil price and the implications of exhaust emissions to the environment from combustion application call for a new reliable alternative fuel. A potential alternative fuel for compression ignition (C.I.) engine is the compressed natural gas (CNG). For C.I. engines to operate using CNG, or to be converted as a retrofitted CNG engine, further modifications are required. Previous works reported loss in brake power (BP) and increase in hydrocarbon (HC) emission for C.I. engine retrofitted with CNG fuelling. Verification of performance characteristics for CNG retrofitted engine through experimental analysis requires high cost and is very time consuming. Thus, a 1-Dimensional simulation software, GT-Power, was introduced in this study to reduce the experimental process and setup. A 4-cylinder medium duty C.I. engine (DE) and CNG retrofitted engine (RE) GT-Power models were used in this simulation work over various operational conditions: low, medium and high load conditions. As compared with DE model, results from RE model showed that RE model achieved an average 4.9% improvement for brake specific fuel consumption (BSFC) and loss in BP by 37.3%. For nitrogen oxides (NOX) and carbon dioxides (CO2) RE model predicted reduction of 48.1% (engine mode 1-9) and 33.4% (all engine modes), respectively. Moreover, RE produced 72.4% more carbon monoxide (CO) and 90.3% more HC emission.

Mono-gas fuelled engine performance and emissions simulation using GT-Power

The scarcity of oil resources and the rise of crude oil price had driven the whole world to seek for an alternative fuel for automotive industry. One of the prospective alternative fuels for compression ignition (C.I.) engine is compressed natural gas (CNG). In order to operate CNG in a C.I. engine as mono-gas engine (RE), several modifications are required. The modifications that involves are compression ratio, fuel injection type, addition of spark plug and fuel itself. So as to reduce the time in preparing the experimental test bed and high cost analytical study a 1-dimensional simulation software GT-Power was introduce. The GT-Power simulation model for a 4 cylinder medium duty C.I. engine (DE) and RE has been built to study the effects of conversion process to the performance and emissions of the engine at various operational conditions: low, medium and high load conditions. As compared with DE model, results from RE model showed loss in brake power (BP) and brake thermal efficiency (BTE) by 37.3% and 19% respectively. Meanwhile, for brake specific air consumption (BSAC) RE predicted to undergo an average of 19412.6 g/kW-h and increment in volumetric efficiency by percentage of difference 22%. In other side, oxides of nitrogen (NOx) RE engine model predicted reduction of 48.1% (engine mode 1-9) and increased in hydrocarbons (HC) by 90.3.

PFI System for Retrofitting Small 4-Stroke Gasoline Engines

Fuel injection system is a promising technology that enhances positively the fuel economy, engine performances and emission reduction, as compared to the conventional carburetor system. Currently, motorcycles using carburetor system are widely used as a mean of transportation especially in urban areas. This conventional fuelling system produces more harmful emissions and consumes more fuel compared to the fuel injection system. It is therefore desirable to have a fuel injection system that can easily be retrofitted to the current on-road motorcycles. This paper presents a review and comparative study using 1-D simulation software - GT-Power, on electronic fuel injection (EFI) system between port-fuel injection (PFI) and direct injection (GDI) system for retrofitment purpose of small 125cc 4-stroke gasoline engine. From this study, PFI system has been selected based on its high brake power, brake torque, and brake mean effective pressure with low brake specific fuel consumption.

Performance and emission characteristics of direct injection C.I engine retrofitted with mono-CNG system

Diesel engines are widely used in logistics and haulage as vehicular prime movers. In the mechanized and fast-moving forward world of today, the consumption of petroleum products has become an important yardstick of a country’s prosperity. This ever-increasing consumption has led the world to face the twin challenge of energy shortage and environmental deterioration. Natural gas has been one of the highly considered alternative fuels for both spark ignition (S.I) and compressed ignition (C.I.) engines. The advantages and benefits of CNG have made it the preferred choice as alternative fuel in the transportation sector. This present study focused on the effects of retrofitted direct injection C.I. engine with mono-CNG system to its performance and exhaust emissions. The engine speed was varied from 850 rpm to 2500 rpm, with load test conditions of 0Nm, 27.12Nm and 53.23Nm, using an engine dynamometer. Results indicated that CNG has the potential to provide better fuel consumption compared to diesel fuel. Meanwhile, the characteristics of exhaust gas emissions such as smoke opacity and CO2 gave promising results compared to CO, HC and NOX, for diesel combustion.

Biodiesel production from multi feedstock as feed with direct ultrasound assisted

The objective of this study was to optimize of ratio oil type, ratio oil to methanol and catalyst concentration. The optimization was used Central Composite Design (CCD). Biodiesel was produced with multi stock oil as feed and conducted in direct ultrasonic radiation. Biosonic equiped with ultrasonic generator with a frequency of 28 kHz. Biodiesel produced at a pressure of 1 atm, reaction time of 60 min and temperature 60 ° C. The optimum conditions of volume ratio for Palm and Coconut oil 4:1, KOH catalyst concentration 0.3% and methanol to oil mole ratio 7:1. Biodiesel yield was determined under this condition and obtained 81.105%.

PFI retrofit-kit as green technology for small 4-stroke S.I. Engine

This paper presents outcomes of the usage of a developed prototype of PFI retrofit-kit for small 4-stroke gasoline engine. The developed PFI retrofit-kit produced good and high brake power and brake mean effective pressure compared to the carburetor system with over 50% improvement. Exhaust-out emissions such as carbon monoxide, carbon dioxide and hydrocarbon have been reduced in the range of 39%, 185%, and 57% respectively. However, brake specific fuel consumption was found to be higher (125%) as compared to carburetor system.

Influence of fuel injector position of port-fuel injection retrofit-kit to the performances of small gasoline engine

Fuel efficiency and emission characteristics are two main concerns that must be addressed. Fuelling system is one of the crucial variables that must be focused on. Fuel injection system has a long term potential as a medium to supply suppressed fuel because of its high fuel delivery efficiency, low emission characteristics and fuel economy. Fuel injector angle plays an important role in achieving quality combustion. In this study the influences of the injector angle to engine performances and emission characteristics were investigated. Experimental works comprised one throttle opening position with various dynamometer loads for two angles: 48° and 68°. From this study, the result shows that 68° was the optimum angle, which produced high brake power, high brake mean effective pressure, low brake specific fuel consumption and low hydrocarbon emission.

Electronic Control Unit Design for a Retrofit Fuel Injection System of a 4-Stroke 1-Cylinder Small Engine

Most motorcycles in developing countries use carburetor systems as the fuel delivery method especially for models with the cubic capacity of less than 125cc. However, small gasoline fuelled engines operating using carburetor system suffer from low operating efficiency, waste of fuel and produce higher level of hazardous emissions to the environment. In this study, an electronic control unit (ECU) is designed and simulated for a retrofit fuel injection (FIS) system. The ECU is targeted to have a simple design, reliable and offers all of the necessary functions of the modern ECU. The simulation results shows that the designed ECU can determine the injection period as close to the proposed value and can drive the injector efficiently based on the generated PWM pulse.