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This paper deals with simulation studies on surface densification of PM gears by rolling process using finite element method. The PM gear is considered as a porous continuum and analysis is performed using constitutive relations based on Gurson model for porous materials. The influence of various parameters such as initial position of mating gears, braking torque applied, friction between mating surfaces and roll stock allowance on the process have been studied. The density obtained by the process is highly influenced by the braking torque applied. The results presented provide a better understanding of the PM gear rolling process.

Copper ion-exchanged X-zeolite with urea infusion was tested for nitrogen oxide (NOx)conversion efficiency in this study. Temperature datapoints were obtained to arrive at peak activation temperatures. Variation of the air/fuel ratio showed the widening of the λ-window(the range of air-fuel ratios over which the NOx conversion efficiency is considerable); a maximum of 62% NOx conversion efficiency was obtained in the lean-burn range. Effects of space velocity variations were also observed. In order to minimise the deactivation of zeolite caused by water, ammonium carbonate and ammonium sulphate were deposited on the copper ion-exchanged X-zeolite and the corresponding NOx conversion efficiencies measured. Ammonia slip (leakage of unreacted ammonia), a prospective pollution hazard, was observed to be more in case of urea infusion than ammonium salt deposition at higher temperatures.

Three catalysts based on X-zeolite have been developed by exchanging its Na+ ion with Copper, Nickel and Vanadium metal ions and tested in a stationary SI engine exhaust to observe their potentialities for NOx and CO controlling. The catalyst Cu-X, in comparison to Ni-X and V-X, exhibits much better NOx and CO reduction performance at any temperature. Maximum NOx conversion efficiencies achieved with Cu-X, Ni-X and V-X are 62.2%, 59.7% and 56.1% respectively. Unlike noble metals, the doped X-zeolite catalysts, studied here, maintain their peak NOx reduction performance through a wider range of A/F ratio. Back pressure developed across the catalyst bed is found to be well within the acceptable limits.

This work demonstrates how the performance of a standard spark-assisted alcohol engine can be improved by using the Low Heat Rejection (LHR ) concept. The improved combustion is attained by better using the greater heat energy in the combustion chamber of a LHR engine - in this case for the faster vaporisation and better mixing of the alcohol fuels. For this program the LHR engine used has a single cylinder diesel and alcohols sued as sole fuels were ethanol and methanol. For spark assistance an extended electrode spark plug was used and location and projection were optimised for best results. These configurations were evaluated for performance and emissions with and without LHR implementation. The results show that the engine with LHR, ethanol fuel and spark assistance has the highest brake thermal efficiency with the lowest emissions.

The performance of a conventional, carbureted, two-stroke spark-ignition (SI) engine can be improved by providing moderate thermal insulation in the combustion chamber. This will help to improve the vaporization characteristics in particular at part load and medium loads with gasoline fuel and high-latent-heat fuels such as methanol. In the present investigation, the combustion chamber surface was coated with a 0.5-mm thickness of partially stabilized zirconia, and experiments were carried out in a single-cylinder, two-stroke SI engine with gasoline and methanol as fuels. Test results indicate that with gasoline as a fuel, the thin ceramic-coated combustion chamber improves the part load to medium load operation considerably, but it affects the performance at higher speeds and at higher loads to the extent of knock and loss of brake power by about 18%. However, with methanol as a fuel, the performance is better under most of the operating range and free from knock.

The use of alcohol-gasoline blends enables the favorable features of alcohols to be utilized in spark ignition (SI) engines while avoiding the shortcomings of their application as straight fuels. Eucalyptus and orange oils possess high octane values and are also good potential alternative fuels for SI engines. The high octane value of these fuels can enhance the octane value of the fuel when it is blended with low-octane gasoline. In the present work, 20 percent by volume of orange oil, eucalyptus oil, methanol and ethanol were blended separately with gasoline, and the performance, combustion and exhaust emission characteristics were evaluated at two different compression ratios. The phase separation problems arising from the alcohol-gasoline blends were minimized by adding eucalyptus oil as a co-solvent. Test results indicate that the compression ratio can be raised from 7.4 to 9 without any detrimental effect, due to the higher octane rating of the fuel blends.

Hydrocarbon emissions due to short-circuiting of the fresh charge during scavenging process is a major source of pollution from the two-stroke spark ignition engines. This work presents a prediction scheme for analysis of hydrocarbon emission based on the material balance considerations. A generalized form of globular combustion equation has been used for general applicability of the scheme to any fuel or fuel blends. The influence of mixture quality, scavenging characteristics, residual contents and the delivery ratio are predicted. A good qualitative prediction has been established at all delivery ratios. The predictions are found quantitatively satisfactory in the higher delivery ratio range where the short-circuiting phase of the scavenging process is dominant.