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The urban drive cycles for five different light duty vehicles (LDV) are developed in this study. The study presents the methodology in the development of the drive cycles in which the speed profile of the specific type of vehicle is surveyed with an on-board instrument. The speed data is processed using a program to execute the methodology in generating candidate drive cycles. The selected drive cycles are then used in the chassis dynamometer laboratory to estimate the fuel economies of each type of light duty vehicle considered. The developed drive cycles for the different types of light duty vehicles, namely (1) private cars, (2) taxis, (3) public utility jeepneys, (4) UV express, and (5) light duty trucks have average speeds of 17.97 kph, 13.57 kph, 10.87 kph, 14.69 kph and 8.43 kph respectively. The measured fuel economies for all the light duty vehicles tested ranges from 3 to 12 km/liter.

This paper presents the results of a two-phase Philippine study to determine the actual mileage (km/liter) of in-use diesel and LPG (liquefied petroleum gas or Auto-LPG) public utility jeepneys plying two separate Metro Manila urban routes using both on-road and chassis dynamometer tests. Measured average load factor in on-road tests was 60-70%. Dynamometer tests at 100% load factor utilized drive cycles derived from on-road speed data. A “diesel equivalent mileage” of actual LPG mileage, deemed indicative of LPG “fuel energy conversion efficiency” relative to diesel, was calculated (based solely on fuel heating values and densities) for comparing actual mileage from both fuels. The LPG actual mileage in both on-road and laboratory tests was lower than diesel mileage. In on-road tests, the LPG actual mileage was lower than diesel actual mileage by about the same percentage LPG heating value was lower than diesel’s per liter of fuel.

The instantaneous fuel consumption measurements obtained from the chassis dynamometer tests using the drive cycles for light duty vehicles in Metro Manila was used in the development of speed-acceleration-fuel consumption models. The Shepard’s interpolation method was used in the development of the models. A program C# language was used to execute the interpolation method.The resulting models are represented by speed-acceleration-fuel consumption surface graphs. The surface graph of each test vehicle represents its estimated fuel consumption variation according to its combined instantaneous speed and acceleration. Actual instantaneous speeds from speed data of surveyed vehicles, defining different traffic conditions by average speed, are used to interpolate instantaneous fuel consumption. Fuel economy, in terms of distance travelled (km) per volume of fuel consumed (liter), is computed from the totaled fuel consumption and total distance traversed.

This paper presents a preliminary study to estimate, using on-road and laboratory tests, the mileage range of liquefied petroleum gas (LPG) as an alternative fuel for diesel-fed public utility jeepneys in the Philippines. Data from the study would be used by the Philippine Department of Energy to formulate and implement alternative fuel programs for public transport. On-road fuel consumption, load factor, and GPS speed data from selected in-use LPG and diesel jeepneys plying a chosen urban route were gathered to develop corresponding drive cycles for chassis dynamometer testing at 100% load factor were conducted to estimate an upper limit for fuel consumption. Measured on-road diesel jeepney mileage was about 6.7 km/liter at 63.5% load factor while that for LPG jeepney was 3.8-4.2 km/liter at 59.8% load factor. Drive cycle tests yielded 5.2 km/liter for diesel and 2.6-3.1 km/liter for LPG.

Dual-fuel operation of a direct-injection diesel engine with natural gas fuel can yield a high thermal efficiency almost comparable to the diesel operation at higher loads. The dual-fuel operation, however, at lower loads inevitably suffers from lower thermal efficiency and higher unburned fuel. To improve this problem, engine tests were carried out on a variety of engine parameters including diesel fuel injection timing advance, intake throttling and hot and cooled exhaust gas recirculation (EGR). It was found that diesel injection timing advance gave little improvement in thermal efficiency and increased NOx. Intake throttling promoted better combustion and shortened its duration with a consequent improvement in efficiency at higher natural gas fractions. Hot EGR raised thermal efficiency, reduced smoke levels, and maintained low NOx levels. Cooled EGR reduced NOx emissions but lowered thermal efficiency.

Maximum efficiency of cyclic combustion engines (CCE) is achieved when using stratified charge and high compression ratio with controlled air circulation and combustion. A description is given of a varying-area, toroidal-shaped combustion chamber designed to achieve the above objectives by: obtaining initial circulatory air motion induced by the piston late in the compression stroke; increasing this piston-induced velocity using the momentum of fuel injected tangentially to the center line of the toroid; and by using combustion to further increase the circulation rate. Four combustion chamber configurations were studied in a bomb with zero initial air velocity to ascertain whether significant rotation could be achieved by injection and combustion. Gas pressure was measured and high speed photographs were taken of the injection and combustion process. The ideal situation, at full load, is to have one rotation of the gas during the time allocated to combustion.