Levent Yüksek

Effect of hydrogen–diesel dual-fuel usage on performance, emissions and diesel combustion in diesel engines

Diesel engines are inevitable parts of our daily life and will be in the future. Expensive after-treatment technologies to fulfil normative legislations about the harmful tail-pipe emissions and fuel price increase in recent years created expectations from researchers for alternative fuel applications on diesel engines. This study investigates hydrogen as additive fuel in diesel engines. Hydrogen was introduced into intake manifold using gas injectors as additive fuel in gaseous form and also diesel fuel was injected into cylinder by diesel injector and used as igniter. Energy content of introduced hydrogen was set to 0%, 25% and 50% of total fuel energy, where the 0% references neat diesel operation without hydrogen injection. Test conditions were set to full load at 750, 900, 1100, 1400, 1750 and finally 2100 r/min engine speed. Variation in engine performance, emissions and combustion characteristics with hydrogen addition was investigated. Hydrogen introduction into the engine by 25% and 50% of total charge energy reveals significant decrease in smoke emissions while dramatic increase in nitrogen oxides. With increasing hydrogen content, a slight rise is observed in total unburned hydrocarbons although CO2 and CO gaseous emissions reduced considerably. Maximum in-cylinder gas pressure and rate of heat release peak values raised with hydrogen fraction.

Optimization of the oil drain interval of non-phosphorus and non-ash engine oil

Purpose Zinc dialkyldithiophosphate (ZDDP) is the most common anti-wear and anti-oxidant additive. ZDDP is the primary origin of zinc, sulfur and phosphorus, which are well-known poisonous elements for commercial after-treatment systems. The aim of this study is to investigate the optimum oil drain interval of non-phosphorus and non-ash (NPNA) engine oil that was developed as a prospective alternative to commercial phosphorus-containing (PC) engine lubricants. Design/methodology/approach The results of a fleet test wear debris analysis were used to optimize the oil drain intervals from the perspective of cost. Findings Drain intervals of 32,000 and 28,000 km were computed as the optimum values for NPNA and PC engine oils, respectively. Extending the oil drain intervals up to the obtained mileage may go to a total saving of €43,045,084.2 for PC engine oil and €49,253,998.6 for NPNA engine oil with respect to the total sales figures of test vehicles in Turkey. Originality/value Maximizing the lubricant life has environmental benefits and is the easiest way to reduce the maintenance cost of a vehicle. The protection of after-treatment systems against lubricant-induced poisoning is a great challenge. The most important result of this investigation is the lower operation costs of catalyst-friendly lubricants in spite of their low anti-wear additive performance.

Surface and wear mechanisms analysis of phosphorous-free and conventional engine lubricants on cylinder liner and piston rings surfaces

Purpose – This paper aims to investigate the wear mechanisms, formations and effectiveness of tribofilms of new developed, antiwear additive which is called mercapthocarboxylate. The mercapthocarboxylate is a sulphur-based and non-phosphorus additive. Design/methodology/approach – The effectiveness of the additive was examined through a set of laboratory endurance tests that applied with single cylinder spark ignition engine. Two types of lubricants were used to compare the engine tests which were thiophosphate (ZDDP) containing engine lubricant (phosphorus containing) and mercapthocarboxylate containing non-phosphorus and non-ash crankcase oil. Lubricants were tested under identical operating conditions for 100 hrs. The surfaces of cylinder liner and piston rings were inspected through optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. Findings – Catalysis-friendly and sulphur-based mercapthocarboxylate additive can be an alternative antiwear additive pa...

An Experimental Investigation of Ethanol-Diesel Blends on Performance and Exhaust Emissions of Diesel Engines

Ethanol is a promising alternative fuel, due to its renewable biobased origin. Also, it has lower carbon content than diesel fuel and it is oxygenated. For this reason, ethanol is providing remarkable potential to reduce particulate emulsions in compression-ignition engines. In this study, performance of ethanol-diesel blends has been investigated experimentally. Tested fuels were mineral diesel fuel (E0D100), 15% (v/v) ethanol/diesel fuel blend (E15D85), and 30% (v/v) ethanol/diesel fuel blend (E30D70). Firstly, the solubility of ethanol and diesel was experienced. Engine tests were carried out to reveal the performance and emissions of the engine fuelled with the blends. Full load operating conditions at various engine speeds were investigated. Engine brake torque, brake power, brake specific fuel consumption, brake thermal efficiency, exhaust gas temperature, and finally exhaust emissions were measured. Performance of the tested engine decreased substantially while improvement on smoke and gaseous emissions makes ethanol blend favorable.

Quantitative comparison of tribological performance of chromium- and zinc-phosphate-coated piston rings in tribotest rig

The main purpose of this paper is to investigate the tribological performance of the zinc-phosphate- and chromium-coated spheroidal cast iron piston rings in reciprocating tribotest rig with conventional commercial lubricant. Results of the experiments showed that tribofilm was formed both on ring and liner surfaces. Zinc phosphate coating was removed from the ring surface after the experiments. Wear rate of liner-chromium-coated ring pair was lower than the liner-phosphate-coated ring. The friction coefficient of the liner-phosphate-coated ring pair ranged from 0.104 to 0.124, lower than the liner-chromium-coated ring, which ranged from 0.114 to 0.129. Change of average surface roughness was also lower in chromium-coated ring (31%) than the phosphate-coated ring (72%). Test results showed that hard chromium-coated ring had better tribological performance and coating efficiency than the phosphate-coated ring due to wear resistance and lower change of average surface roughness.