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Proposal This paper presents the experimental results carried out to evaluate the exhaust emissions and performance evaluation of a computer integrated bi-fuel spark ignition engine that has been retrofitted for two fuels namely compressed natural gas (CNG) and base fuel gasoline, operations under steady state with lean burn condition. The used engine was a Proton Magma 4-cylinders spark ignition engine. The emission results such as CO, HC and NOx were measured and compared between the above two fuels. A locally produced three way catalytic converter (TWC) consisting of platinum (Pt), palladium (Pd), cerium oxide (CeO2) and rhodium (Rh) was used to assess the emissions. The CeO2 was used in TWC as an oxygen storage capacity (OSC) to enhance the oxidation process for CO and HC oxidations. The results show that the arrangement of retrofitting catalytic converter and operation with lean burn condition is very effective to reduce exhaust emissions. From the investigation, it is found that CNG produced 15% less brake power, 15%-18% less specific fuel consumption (SFC) and 10% higher thermal efficiency than gasoline fuel. The emission results showed at the entrance of TWC that CNG produced 30% higher NOx emissions and lower 12% and 90% HC and CO respectively. The details about the emissions management system together with the catalytic and engine performance results have been presented and discussed. The results of this investigation will be used to develop new monofueled natural gas engines as well as to develop CNG emissions based TWC. Key words: CNG, Catalyst, Environment, Emissions, Retrofitting. Introduction Natural gas will be the prime car engines fuel between the years of 2010 to 2060. Good ignition and physicochemical properties together with simplicity of the CNG fuel molecule that gives soot-free complete combustion have increased its demand to the vehicle users. The increasing demand of the natural gas vehicle together with the stringent emission requirements have led to active researches on engine management system for further reduction of pollutants emission. Emphasis has been given on the development of alternative fuels like CNG combustion and emissions-after treatment device in vehicle uses. Since last twenty years many research investigations have been done on natural gas fueled engines [1]. These investigations were basically limited in the research laboratory rather than implementation through engine manufacturing company. This is mainly due to the lack of -refueling stations,information about natural gas reservations,technical development in engines optimization and lack of environmental pollution awareness. Anyway, after arrival of stringent emissions regulations to reduce environment pollution starting since last end of the centaury, [2,3] global awareness is raised up to look into alternative fuels to replace fossil petroleum fuels. With this drawback and after confirmation of huge gas reservation, many countries in the world took initiatives to increase NGV. Malaysia among of the Asian countries, is trying to produce new natural gas engines to replace gasoline and diesel fueled vehicles. Currently, petronas NGV Co. Ltd. [4] is involved in exploring the feasibility of converting existing diesel and gasoline engines into natural gas fueled engine. The number of registered vehicles in Malaysia is about 12 millions with 51% of them using gasoline engines (Source internet: Ministry of transport Malaysia, 2004). At present, there are six to seven thousands taxi cab running on bi-fuel system and the government is trying to promote bi-fuel high way car vehicles. Currently, the price of natural gas is 55% lower than gasoline fuel (Fig.1). This country has 50 years gas reservation as compared to ten years petroleum reservation. The government planned regarding refueling stations for CNG can be seen in Fig.2. With this reservation status, the government is trying to promote the utilization of NG through replacing fossil fueled vehicles with CNG fueled vehicle.

Proposal The emergent alarm about the fast depletion of petroleum-based fuels and the environmental pollution caused by their combustion has been a compelling incentive to all researchers to find out the ways to use environmentally friendly and renewable resources of energy and also by technologies to increase vehicle energy efficiency. CNG (compressed natural gas) is the most desirable alternative fuel option to the researchers today for facing the energy crisis and environmental pollution problems properly. This is because of its availability, low exhaust emissions, superior performance and longer engine service life. Malaysia also trying to diversify its automotive fuel options by introducing new mono fuelled CND/DI (direct injection compressed natural gas) engine for utilizing the substantial advantages of CNG fully as an automotive fuel. In the present study a bi-fuel proton car engine has been run with gasoline and CNG and the performance and exhaust emissions of the engine are analyzed & compared. This result will be used as a basis for examining the performance and emissions of Malaysian new CNG/DI engine in future. Present study also focuses on the Malaysian mono fuel CNG/DI engine. From the experimental results, it is found that CNG produced less power, consumed less fuel per kwh and emitted less CO, CO2, HC and more NOx compared to gasoline.It is suggested to build up lighter CNG storage tank and widespread networks of CNG supply stations through out the country for general acceptance of CNG as an automotive fuel. Key words: Air pollution, engine performance, compressed natural gas and Energy security. Introduction It is well known that fossil fuel reserves all over the world are diminishing at an alarming rate and a shortage of crude oil is expected at the early decades of this century. In addition to this, the deteriorating quality of air we breathe is becoming another great public concern and tighter regulation of both ‘local’ and ‘global’ emissions from engines is anticipated. In view of the versatility of ICE (internal combustion engine), it will remain to lead the transportation sector as there is a significant restriction for the battery and fuel cell powered vehicles with respect to range and acceleration. The power to weight ratio of the ICE (including the tank and fuel) is much more than that of the battery powered or fuel cell operated vehicles [1]. These factors have lead scientists and researchers to develop environment-friendly technologies and to introduce more clean fuels alternatives to the conventional fuels used to power ICEs for ensuring the safe survival of the existing engine technology. Apart from limited life period, the other problem with unrestricted combustion of fossil fuels is the level of CO2 emission into the Earth's atmosphere. This has resulted in an increased interest to use NG (natural gas) as fuel for internal combustion engines. The merits of CNG as an automotive fuel over conventional fuels are many and presented nicely by Nylund et al. and Aslam et al. [2–3]. Its composition varies and depends on its source. The world total NG reserve as of January 1, 2004 was 6,076 Tscf and based on the current consumption rates, the estimated total recoverable gas, including proven reserves is adequate for almost 70 years[4]. The difference between the operation of the conventional gasoline fuelled and CNG engine system arises from the physical and chemical properties of the two fuels. It is well-known that the petroleum fuels are liquid at room temperature and CNG remains in a gaseous state at much lower temperature (-161oC). Due to some of its favorable physio-chemical properties CNG appears to be an excellent fuel for the SI (spark ignition) engine and SI engines can be converted to NG operation quite easily for with the addition of a second fueling system. Already it has been successfully used to power vehicles of various ranges, starting from light delivery trucks to full size urban buses. CNG has been used in vehicles since 1930's and the current worldwide NGV population is more than 3.9 million according to the IANGV (International Association for Natural Gas Vehicle) statistics and this figure is fast increasing everyday. But most of the NGV engines are converted from gasoline engines and it produces about 10–15 % less power than the same engine fuelled by gasoline [5]. Another main drawback is the heavier fuel storage tank and vehicle range is compromised for avoiding very large storage tank. However, NG has the potential for increased engine efficiency if the engine is designed for dedicated natural gas operation.

This paper presents experimental results carried out to develop co-relation and comparison between vehicle and stationary dynamometer-engine emissions with same engines specifications and brands. The dynamometer-engine has been setup with same load and speed as the vehicle’s engine which is carried on the road. The vehicle’s road load power carried by engine has been calculated and used in this investigation. The stationary engine’s rotational speed has been converted to linear distance to compare specific fuel consumptions (SFC) with real specific fuel consumption (SFC) of the vehicle on the road. The vehicle has been run on road test at 70km/h, 90 km/h and 100 km/h for 100 km each time to measure fuel consumption. Beside this, both the engine and vehicle have been operated in idling condition to measure fuel consumption, CO and HC emissions. Proton vehicle with magma engine (4 cylinders) has been used in this investigation. Both the engine and vehicle have been retrofitted for two fuels namely gasoline fuel and compressed natural gas (CNG). An eddy current dynamometer model Froude Consine (model AG150) is used to test the engine. All the electronic equipment, together with its manipulative controls and indicators such as thermocouples are mounted on ‘CP Cadet10 (UK)’ engine control unit. The engine control unit can control any speed and load applied to the dynamometer-engine. An autocheck model (974/5) and Bacharach model CA300NSX analyzers (standard version, k-type probe) have been used to measure the concentration CO and HC emissions. The results of this investigation will be used to predict the emissions and fuel consumption for road vehicles from stationary dynamometer–engine test.

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