Development of a CNGDI-Electric Hybrid Vehicle Z.Taha, R. Ariffin, N.Ahmad, Y.H. Jen, T.Yusuf, S.Z.Dawal Centre For Product Design And Manufacture Faculty Of Engineering, University Of Malaya, 50603 Kuala Lumpur MALAYSIA Abstract Natural gas is an alternative to gasoline as a fuel for automotive engines. The combustion of natural gas produces mainly water and C02 and significantly less CO and UHC emissions. In many cases, CNG vehicles generate fewer exhaust and greenhouse gas emissions than their gasoline or diesel- powered counterparts. While it is clean burning and in plentiful supply with a reasonably even global distribution, its drawback is that it is less energy dense than petrol and so has required either a large tank or a reduced driving range Using it in conjunction with electric drive as in an electric hybrid vehicle, this disadvantage would be significantly reduced. In this paper we present results of the first stage of our research that is conversion of a gasoline vehicle to run on direct injected compressed natural gas. We also present a proposed scheme for a CNGDI-electric hybrid vehicle. I. INTRODUCTION Natural gas is one of the most widely used forms of energy today. Natural gas has been recognized as a leading candidate as an alternative fuel in internal combustion engines in the near future. The combustion of natural gas produces mainly water and CO2 and significantly less CO and UHC emissions. In many cases, CNG vehicles generate fewer exhaust and greenhouse gas emissions than their gasoline or diesel-powered counterparts. Internal combustion engines can be powered by natural gas without significant effort in production and distribution since raw natural gas needs minimal processing before distribution [4,5]. While it is clean burning and in plentiful supply with a reasonably even global distribution, its drawback is that it is less energy dense than petrol and so has required either a large tank or a reduced driving range. Using it in conjunction with electric drive as in an electric hybrid vehicle, this disadvantage would be significantly reduced. The electric drive motor is used to augment the internal combustion engine (ICE), enabling use of a smaller engine than required in a conventional vehicle, and enabling the ICE to be operated more efficiently. There are two basic types of hybrid electric drive systems: parallel hybrid drive systems and series hybrid drive systems. In the parallel drive system, the electric motor supplies additional power and torque for brief power surges to the ICE. During these periods, the mechanical power required to move the vehicle is essentially provide for both by the ICE and the electric motor, allowing the ICE to be operated at its most efficient speed. For the series hybrid approach, the ICE is used to generate electricity which is stored and then converted back to mechanical power. The electric motor is the sole means of moving the vehicle's wheels, as the ICE is mechanically decoupled from the drive train.. When a gasoline or diesel engine is converted directly to use CNG, natural gas and air is mixed in the intake manifold. As a result the engine power is reduced and the upper speed restricted. Direct injection can mitigate these by injecting fuel after the intake valve is closed. Thus, the cylinder receives the maximum possible mass of air. In this paper we describe the first stage of our research that is conversion of a gasoline vehicle to run on direct injected compressed natural gas. We also present the proposal to covert the vehicle to a hybrid vehicle with a rear mounted 32KW motor. Currently only the Toyota Prius which is a hybrid vehicle has been adapted to run on CNG and also a Chrysler Neon has been converted into a CNG -Electric vehicle. II. SIMULATION Simulation is done to compare the performance of port injected gasoline, port injected CNG and direct injected CNG [2,3]. Assumptions were made that there is perfect mixture in the combustion chamber and the CNG properties are similar to methane. Table 1 shows some of the important parameter of the engine. TABLE I ENGINE PARAMETERS Gasoline Port CNG-Direct Parameter Injection Injection (G-PI) (DI) Bore 76 mm 76 Stroke 88 mm 88 Compression 10 10 ratio Inhaled air 1OOKpag298K 1OOKpag293K Start of -5 -10 1-4244-0427-4/06/$20.00 ©2006 IEEE - 29 - Oct. 18 -Oct. 20, 2006 FOST2006