Preliminary research on the co-combustion process of ammonia in a compression-ignition engine

In this paper, the effect of high-pressure injection pressure on particulate matter (PM) and nitrogen oxide (NOx) emissions is discussed. Many studies have been conducted by active researchers on high-pressure engines; however, the problem of reducing PM and NOx emissions is still not solved. Therefore, in the existing diesel (compression ignition) engines, the common rail high-pressure injection system has limitations in reducing PM and NOx emissions. Accordingly, to solve the exhaust gas emission problem of a compression ignition engine, a compression ignition engine using an alternative fuel is discussed. This study was conducted to optimize the dimethyl ether (DME) engine system, which can satisfy the emission gas exhaust requirements that cannot be satisfied by the current common rail diesel compression ignition engine in terms of efficiency and exhaust gas using DME common rail compression ignition engine. Based on the results of this study on diesel and DME engines under common rail conditions, the changes in engine performance and emission characteristics of exhaust gases with respect to the injection pressure and injection rate were examined. The emission characteristics of NOx, hydrocarbons, and carbon monoxide (CO) emissions were affected by the injection pressure of pilot injection. Under these conditions, the exhaust gas characteristics were optimized when the pilot injection period and needle lift were varied.

Effect of hydroxy (HHO) gas addition on performance and exhaust emissions in compression ignition engines

Influence of soy-lecithin as bio-additive with straight vegetable oil on CI engine characteristics

A comprehensive review on combustion, performance and emission aspects of higher alcohols and its additive effect on the diesel engine

Effect of ceramic coating on the performance, emission, and combustion characteristics of ethanol DI diesel engine

Environmental pollution and fossil fuel depletion are the major concerns in the present situation. Researchers have tried various biofuels for compression ignition (CI) engine in order to overcome these problems. Waste cooking oil (WCO) was found to be suitable alternate fuel for CI engine because of their huge availability, economically cheaper and renewable capability. However, WCO has poor fuel properties which led to inferior combustion in CI engine. Due to inferior combustion, engine performance was poor, engine exhaust emissions were higher. In this experimental work, different techniques were adopted to improve the performance of CI engine using WCO, as the base fuel. WCO was collected in bulk from a restaurant and used for the entire research work. A single cylinder, four stroke, direct injection, water cooled CI engine was used for this research work. In the first phase of work, experiments were conducted using diesel, WCO as fuel and kept as baseline data. WCO was converted into waste cooking oil biodiesel (WCOB) through transesterification process and conducted experiments using WCOB in the second phase of this work. In the third phase of the work, copper oxide nanofluids were prepared by wet chemical method in four mass concentrations, blended with WCOB and experiments were conducted. Finally, all the experimental outputs from various techniques were compared and analysed. It was observed that WCO produced lower brake thermal efficiency (BTE) and higher exhaust emissions than diesel. In the second phase, BTE was improved while using WCOB as compared to WCO. HC, CO emissions and smoke opacity were reduced. But nitric oxide (NOx) emission was found to be increased as compared to WCO. It was noted that BTE was improved further while using copper oxide nanofluids blended with WCOB. Emissions and smoke were drastically reduced as compared to WCOB and WCO.

Effect of hydrogen addition on performance and emission characteristics of a common-rail CI engine fueled with diesel/waste cooking oil biodiesel blends

The importance of biodiesel as a renewable and economically viable alternative to fossil diesel for applications in compression ignition (CI) engines has led to intense research in the field over the last two decades. This is predominantly due to the depletion of petroleum resources, and increasing awareness of environmental and health impacts from the combustion of fossil diesel. Biodiesel is favoured over other biofuels because of its compatibility with present day CI engines, with no further adjustments required to the core engine configurations when used in either neat or blended forms. Studies conducted to date on various CI engines fuelled with varying biodiesel types and blends under numerous test cycles have shown that key tailpipe pollutants, such as carbon monoxide, aromatics, sulphur oxides, unburnt hydrocarbons and particulate matters are potentially reduced. The effects of biodiesel on nitrogen oxides emission require further tests and validations. The improvement in most of the diesel emission species comes with a trade-off in a reduction of brake power and an increase in fuel consumption. Biodiesel’s lubricating properties are generally better than those of its fossil diesel counterpart, which result in an increased engine life. These substantial differences in engine-out responses between biodiesel and fossil diesel combustion are mainly attributed to the physical properties and chemical composition of the fuels. Despite the purported benefits, widespread adoption of biodiesel usage in CI engines is hindered by outstanding technical challenges, such as low temperature inoperability, storage instabilities, in-cylinder carbon deposition and fuel line corrosion. It is imperative that these issues are addressed appropriately to ensure that long-term biodiesel usage in CI engines does not negatively affect the overall engine durability. Possible solutions range from biodiesel fuel reformulation through feedstock choice and production technique, to the simple addition of fuel additives. This calls for a more strategic and comprehensive research effort internationally, with an overarching approach for co-ordinating sustainable exploitation and utilisation of biodiesel. This review examines the combustion quality, exhaust emissions and tribological impacts of biodiesel on CI engines, with specific focus on the influence of biodiesel’s physico-chemical properties. Ongoing efforts in mitigating problems related to engine operations due to biodiesel usage are addressed. Present day biodiesel production methods and emerging trends are also identified, with specific focus on the conventional transesterification process wherein factors affecting its yield are discussed.

In this study, hydroxy gas (HHO) was produced by the electrolysis process of different electrolytes (KOH(aq), NaOH(aq), NaCl(aq)) with various electrode designs in a leak proof plexiglass reactor (hydrogen generator). Hydroxy gas was used as a supplementary fuel in a four cylinder, four stroke, compression ignition (CI) engine without any modification and without need for storage tanks. Its effects on exhaust emissions and engine performance characteristics were investigated. Experiments showed that constant HHO flow rate at low engine speeds (under the critical speed of 1750 rpm for this experimental study), turned advantages of HHO system into disadvantages for engine torque, carbon monoxide (CO), hydrocarbon (HC) emissions and specific fuel consumption (SFC). Investigations demonstrated that HHO flow rate had to be diminished in relation to engine speed below 1750 rpm due to the long opening time of intake manifolds at low speeds. This caused excessive volume occupation of hydroxy in cylinders which prevented correct air to be taken into the combustion chambers and consequently, decreased volumetric efficiency was inevitable. Decreased volumetric efficiency influenced combustion efficiency which had negative effects onengine torque andexhaust emissions.Therefore, ahydroxy electroniccontrol unit (HECU)wasdesignedandmanufacturedtodecreaseHHOflowratebydecreasingvoltageand

The article presents the results of research on the influence of two fuel additives that selectively affect the combustion process in a diesel engine cylinder. The addition of NitrON® reduces the concentration of nitrogen oxides (NOx), due to a reduction in the kinetic combustion rate, at the cost of a slight increase in the concentration of particulate matter (PM) in the engine exhaust gas. The Reduxco® additive reduces PM emissions by increasing the diffusion combustion rate, while slightly increasing the NOx concentration in the engine exhaust gas. Research conducted by the authors confirmed that the simultaneous use of both of these additives in the fuel not only reduced both NOx and PM emissions in the exhaust gas but additionally the reduction of NOx and PM emissions was greater than the sum of the effects of these additives—the synergy effect. Findings indicated that the waveforms of the heat release rate (dQ/dα) responsible for the emission of NOx and PM in the exhaust gas differed for the four tested fuels in relation to the maximum value (selectively and independently in the kinetic and diffusion stage), and they were also phase shifted. Due to this, the heat release process Q(α) was characterized by a lower amount of heat released in the kinetic phase compared to fuel with NitrON® only and a greater amount of heat released in the diffusion phase compared to fuel with Reduxco® alone, which explained the lowest NOx and PM emissions in the exhaust gas at that time. For example for the NOx concentration in the engine exhaust: the Nitrocet® fuel additive (in the used amount of 1500 ppm) reduces the NOx concentration in the exhaust gas by 18% compared to the base fuel. The addition of a Reduxco® catalyst to the fuel (1500 ppm) unfortunately increases the NOx concentration by up to 20%. On the other hand, the combustion of the complete tested fuel, containing both additives simultaneously, is characterized, thanks to the synergy effect, by the lowest NOx concentration (reduction by 22% in relation to the base). For example for PM emissions: the Nitrocet® fuel additive does not significantly affect the PM emissions in the engine exhaust (up to a few per cent compared to the base fuel). The addition of a Reduxco® catalyst to the fuel greatly reduces PM emissions in the engine exhaust, up to 35% compared to the base fuel. On the other hand, the combustion of the complete tested fuel containing both additives simultaneously is characterized by the synergy effect with the lowest PM emission (reduction of 39% compared to the base fuel).

Performance and emission characteristics of a CI engine operated with n-Butane blended DME fuel

Ethanol is a promising renewable oxygenated fuel for engines, and many experimental studies on the using of ethanol-diesel fuel blends in diesel engines have been done. But modeling studies on ethanol blends are very scarce. For this reason; the present study intends to investigate numerically the effects of the use of ethanol-diesel fuel blends on the engine performance characteristics such as brake specific fuel consumption (BSFC), brake effective power, brake effective efficiency, exhaust emissions, and cost by using two different turbocharged direct-injection (DI) diesel engines. A computer program has been used for prediction of diesel engine cycles and engine characteristics for the case of neat diesel fuel (NDF) and this program was modified for ethanol-diesel fuel blends. In the diesel engine cycle modeling, a quasi-dimensional phenomenological combustion model previously developed by authors has been used. This model is based on the model originally developed by Shahed and then improved by Ottikkutti, and it has been modified by the authors with new assumptions. By doing some modifications and adaptations in this model it has been converted to the ethanol-diesel fuel blends version. After the engine cycle model for NDF and ethanol-diesel fuel blends was proven to give correct results by comparing with relevant experimental and numerical results, (2-10) % ethanol-diesel fuel blends have been investigated numerically. The results indicate that as ethanol percentage in the mixture increases, BSFC reduces and brake effective efficiency improves significantly and brake effective power increases slightly. On the other hand, equivalence ratio decreases and ignition delay increases for ethanol blends, and combustion duration exhibits generally a decreasing tendency. The concentrations of nitric oxide (NO), the mole fractions of carbon monoxide (CO), and hydrogen (H 2 ) increase at low ethanol ratios because of increase of the temperatures of the cylinder contents. But at high ethanol ratios they decrease because of decreasing temperatures. In the present study, cost analysis has also been performed by using a semi empirical relation given by Durgun. It was determined that ethanol blends are not economical for these engines because the cost of ethanol is higher than that of diesel fuel in Turkey, as well as in many of the other countries, and the decrease in the BSFC is low. In the present study, the effects of the using of ethanol blends at constant equivalence ratios (CER) have also been investigated. In this application, BSFC enhances with increasing ethanol ratios. Also, brake effective power, brake effective efficiency, and combustion duration increase until (4-6) % ethanol ratios at CER and after these ratios they start to decrease. NO concentration and the mole fractions of CO and H 2 show generally a decreasing tendency.

Reduction of exhaust emissions is a major research task in diesel engine development in view of increasing concern regarding environmental protection and stringent exhaust gas regulations. Simultaneous reduction of NOx emissions and particulate matter is quite difficult due to the soot/NOx trade-off and is often accompanied by fuel consumption penalties. Towards this aim, automotive engineers have proposed various solutions, one of which is the use of alternative gaseous fuels as a supplement for the commercial liquid diesel fuel. This type of engine, which operates fuelled simultaneously with conventional diesel oil and gaseous fuel, is called “dual fuel” diesel engine. Among alternative gaseous fuels, natural gas is considered to be quite promising due to its low cost and its higher auto-ignition temperature compared to other gaseous fuels facilitating thus its use on existing diesel engines. Previous research studies revealed that natural gas/diesel engine operation results in deterioration of brake engine efficiency, CO and HC emissions compared to conventional diesel fuel operation. In attempt to curtail these negative effects, various theoretical and experimental studies were carried out examining the influence of various parameters such as pilot fuel quantity, diesel fuel injection timing advance and intake charge conditions on “dual fuel” engine performance characteristics and pollutant emissions. However, there are more to know about the proper combination of these engine parameters to attain the optimum results regarding reduction of CO and HC emissions without further deteriorating, if not improving, brake engine efficiency. Hence, in the present study, a theoretical investigation is conducted using an engine simulation model to examine the effect of the aforementioned parameters on performance and exhaust emissions of a natural gas/diesel engine. Predictions are produced for a high-speed natural gas/diesel engine performance characteristics and NO, CO and Soot emissions at diverse engine speeds and loads using a comprehensive two-zone combustion model. The main objective of this comparative assessment is to elaborate the relative impact of each one of the above mentioned parameters on engine performance characteristics and exhaust emissions. Furthermore, an endeavor is made to determine the optimum combinations of these engine operational parameters. The conclusions of this study may be proven to be considerably valuable for the application of this technology on existing DI diesel engines.

Potential of Atkinson cycle combined with EGR for pollutant control in a HD diesel engine

An experimental investigation into the combustion properties, performance, emissions, and cost reduction of using heavy and light fuel oils