Biodiesel, a fuel that can be made from renewable biological sources such as vegetable oils or animal fats, has been recognized recently as an environment friendly alternative fuel for diesel engines. In this paper, we describe a study that compared exhaust emissions from in-use heavy trucks fueled with a biodiesel blend with those from trucks fueled with petroleum diesel. The biodiesel blend tested is a mixture of 35% biodiesel and 65% petroleum diesel, a blend designated as B35. The study is based on the field test results from West Virginia University's Transportable Heavy Duty Chassis Dynamometer Emissions Testing Laboratory and sponsored by the U.S. Department of Energy. The heavy trucks we tested performed well when the originally equipped compression-ignition engine (diesel engine) was fueled with B35 without any engine modifications. Fuel economy (in terms of gallon per mile) of the two fuels was about the same. The emissions test results have shown that the heavy trucks fueled by B35 emitted significantly lower particulate matter (PM) and moderately lower carbon monoxide (CO) and hydrocarbon (HC) than the same trucks fueled by no. 2 diesel (D2). Oxides of nitrogen (NO x ) emissions from B35 and D2, however, were generally in the same level. Emissions variations from two different engine models and two driving cycles were also observed. Although we recommend more tests for biodiesel vehicles, the data obtained in this study indicate that biodiesel has promise as an emissions-reducing alternative fuel for diesel engines.

In this paper, the development of a general approach is presented, aimed at the parametric design modelling qf internal combustion engine systems. This approach allows optimization procedures to be applied which yield optimum characteristics of the engine in terms of single-or multi-performance criteria and under specific requirements of speed and power.

This paper develops an alternative optimization approach for systematic design of a parametrized engine system and illustrates the procedure through application to a novel conversion device, the patented Stiller-Smith mechanism ( I , 2). Using simultaneous interplay between a simulation scheme, presented in detail elsewhere (J), and an optimization scheme, the proposed structural design process integrates the multiple objectives of structural design. Developed here in detail, optimization involves intermediate continuous optimization via a penalty function method, and integer or discrete programming through the branch-and-bound algorithm. The ensuing application illustrates the approach by optimizing a 16-cylinder Stiller-Smith engine for minimum weight-power and dimensions-power ratios under several types of constraints. In the context of a multi-objective constrained non-linear programming problem, the design example proceeds through three stages: (a) preliminary, in which the designer applies the simulation scheme to obtain the system response variables from the design requirements to reject trade-off relationships among multiple design objectives; (b) secondary, the intermediate continuous optimal design stage, in which a penalty function method is used to specify constraints within a general range to allow variation in the choice of parameters; and (c) final, in which the branch-and-bound algorithm constrains integer variables to take integer values and discrete variables to take discrete values, thereby arriving at an optimal design. NOTATIONDO3990 (9 IMechE 1991 0940-4010/91 $2.00 i .05 Pmc lnstn Mech Engrs Vol 205 at RMIT UNIVERSITY on July 15, 2015 pid.sagepub.com Downloaded from @ IMechE 1991 at RMIT UNIVERSITY on July 15, 2015 pid.sagepub.com Downloaded fromX, = S/B, the stroke-bore ratio X2 = S/D, the stroke-gear diameter ratio X , = P, the diametrical pitch of the gear X4 = N,, number of teeth constrained by the integer X , = Lp/B, the piston head length-bore ratio X , = F, , axial gear width X , = S, , yield strength of material used A' , = dpn , the pin diameter X , = do,, output shaft diameter X l 0 = 1, , connecting rod length X , , = h, , connecting rod width X,2 = t, , connecting rod thickness X , , = lo,, output shaft length Xi4 = counterweight gravity centre to axis of output Q

The development of a mathematical model of Stiller-Smith mechanism for the application of a four-cylinder plunger pump system is presented. The magnitude and direction of the internal dynamic load are obtained by solving a set of equations using the overall geometric parameters, prescribed motions, inertia distribution and applied torques on the system. The simulation presented here yields lhe history of the internal loads, which are then normalized with respect to the required peak output load on the plungers, through an entire rotary cycle. The approach allows for the development of further design criteria through parametric sensitivity studies. NOTATION