Cherng-Yuan Lin

The fuel properties of three-phase emulsions as an alternative fuel for diesel engines☆☆

Diesel engines are employed as the major propulsion power for in-land and marine transportation vehicles primarily because of their rigid structure, low breakdown rate, high thermal efficiency and high fuel economy. It is expected that diesel engines will be widely used in the foreseeable future. However, the pollutants emitted from diesel engines (in particular nitrogen oxides and particulate matter) are detrimental to the health of living beings and ecological environment have been recognized as the major air pollution source in metropolitan areas and have thus attracted much research interest. Although diesel oil emulsion has been considered as a possible approach to reduce diesel engine pollutants, previous relevant applications were restricted to two-phase emulsions. Three-phase emulsions such as oil-in-water-in-oil briefly denoted as O/W/O emulsions and water-in-oil-in-water, denoted as W/O/W, have not been used as an alternative fuel for any combustion equipment. Studies on the properties of three-phase emulsion as fuel have not been found in the literatures. The emulsification properties of an O/W/O three-phase diesel fuel emulsion were investigated in this experimental study. The results show that the mean drop size of the O/W/O emulsion was reduced significantly with increasing homogenizing machine revolution speed. An increase in inner phase proportion of the O/W/O emulsion resulted in increasing the emulsion viscosity. The viscosity of O/W/O emulsion is greater than that for water-in-oil (denoted briefly as W/O emulsion) for the same water content. More stable emulsion turbidity appeared for three-phase O/W/O diesel emulsions added with emulsifier with HLB values ranging from 6 to 8. In addition, three-phase O/W/O emulsions with greater water content will form a larger number of liquid droplets, leading to a faster formation rate and greater emulsion turbidity at the beginning but a faster descending rate of emulsion turbidity afterwards. The potential for using O/W/O emulsions as an alternative fuel for diesel engines was also evaluated.

An oxygenating additive for improving the performance and emission characteristics of marine diesel engines

Abstract Diesel engines provide the major power sources for marine transportation and contribute to the prosperity of the worldwide economy. However, the emissions from diesel engines also seriously threaten the environment and are considered one of the major sources of air pollution. The pollutants emitted from marine vessels are confirmed to cause the ecological environmental problems such as the ozone layer destruction, enhancement of the greenhouse effect, and acid rain, etc. Marine diesel engine emissions such as particulate matter and black smoke carry carcinogen components that significantly impact the health of human beings. Investigations on reducing pollutants, in particular particulate matter and nitrogen oxides are critical to human health, welfare and continued prosperity. The addition of an oxygenating agent into fuel oil is one of the possible approaches for reducing this problem because of the obvious fuel oil constituent influences on engine emission characteristics. Ethylene glycol monoacetate was found to be a promising candidate primarily due to its low poison and oxygen-rich composition properties. In this experimental study ethylene glycol monoacetate was mixed with diesel fuel in various proportions to prepare oxygenated diesel fuel. A four-cylinder diesel engine was used to test the engine performance and emission characteristics. The influences of ethylene glycol monoacetate ration to diesel oil, inlet air temperature and humidity parameters on the engine’s speed and torque were considered. The experimental results show that an increase in the inlet air temperature caused an increase in brake specific fuel consumption (BSFC), carbon monoxide, carbon dioxide emission, and exhaust gas temperature, while decreasing the excess air, oxygen and nitrogen oxide emission concentrations. Increasing the inlet air humidity increased the carbon monoxide concentration while the decreased excess air, oxygen and nitrogen oxide emission concentrations. In addition, increasing ethylene glycol monoacetate ratio in the diesel fuel caused an increase in the BSFC while the excess air and oxygen emission concentrations decreased.

Reduction of particulate matter and gaseous emission from marine diesel engines using a catalyzed particulate filter

Abstract Diesel engines are used widely as the power sources of coastal ships and international vessels primarily due to their high thermal efficiency, high fuel economy and durable performance. However, the gaseous and solid substances exhausted from diesel engines during the combustion process cause air pollution, in particular around harbor regions. In order to effectively reduce particulate matter and gaseous pollution emissions, a catalyzed particulate filter was equipped in the tail pipe of a marine diesel engine. The engines performance and emission characteristics under various engine speeds and torques were measured using a computerized engine data control and acquisition system accompanied with an engine dynamometer. The effectiveness of installing a catalyzed particulate filter on the reduction of pollutant emissions was examined. The experimental results show that the exhaust gas temperature, carbon monoxide and smoke opacity were reduced significantly upon installation of the particulate filter. In particular, larger conversion of carbon monoxide to carbon dioxide — and thus larger CO2 and lower CO emissions — were observed for the marine diesel engine equipped with a catalyzed particulate filter and operated at higher engine speeds. This is presumably due to enhancement of the catalytic oxidation reaction that results from an exhaust gas with stronger stirring motion passing through the filter. The absorption of partial heating energy from the exhaust gas by the physical structure of the particulate filter resulted in a reduction in the exhaust gas temperature. The particulate matter could be burnt to a greater extent due to the effect of the catalyst coated on the surface of the particulate filter. Moreover, the fuel consumption rate was increased slightly while the excess oxygen emission was somewhat decreased with the particulate filter.

Effects of Diesel Engine Speed and Water Content on Emission Characteristics of Three-Phase Emulsions

Abstract The effects of water content of three-phase emulsions and engine speed on the combustion and emission characteristics of diesel engines were investigated in this study. The results show that a larger water content of water-in oil (W/O) and oil-in-water-in-oil (O/W/O) emulsion caused a higher brake specific fuel consumption (bsfc) value and a lower O2, as well as a lower NOx emission, but a larger CO emission. The increase in engine speed resulted in an increase of bsfc, exhaust gas temperature, fuel-to-air ratio, CO2 emission and a decrease of NOx, CO emission, and smoke opacity. Because of the physical structural differences, the three-phase O/W/O emulsions were observed to produce a higher exhaust gas temperature, a higher emulsion viscosity and a lower CO emission, in comparison with that of the two-phase W/O emulsion. In addition, the use of W/O emulsions with water content larger than 20% may cause diesel engines to shut down earlier than those running on O/W/O emulsions with the same water content. Hence, it is suggested that the emulsions with water content larger than 20% are not suitable for use as alternative fuel for diesel engines.

The effects of sodium sulfate on the emissions characteristics of an emulsified marine diesel oil-fired furnace

Abstract Degraded diesel oils are commonly used in marine power plants to conform to the demands of shipowners for fuel economy. The burning of these marine fuel oils, which frequently contain various extents of oxides of iron, silicon, calcium, vanadium and potassium, such as Na 2 SO 4 , Fe 2 O 3 , SiO 2 , CaO, V 2 O 5 , etc., are susceptible to form much more complex compounds of either gaseous or solid phases. The release of these emissions to the environment may cause atmospheric pollution and a health hazard to human beings. Emulsification of a fuel oil with water to produce a micro-water-particles-dispersed-in-oil (W/O) emulsion has been considered as one of the promising techniques to improve combustion characteristics of low-grade marine oils and in turn effectively help to reduce the release of air pollutants. Marine fuel oil A, which approximates ASTM No. 2D oil was used as the test oil and the surfactant Span 80 was used to promote the affinity and integrating force between the components of the emulsion. An emulsifying/homogenizing machine was employed to stir the emulsion mixture of the marine oil, distilled water, surfactant Span 80 and sodium sulfate (Na 2 SO 4 ) powder of 300 ppm. The mechanically blended emulsion mixture was injected, atomized and burned in an oil-fired furnace using an automatic burner. Burning gas composition, burning efficiency and gas temperature were measured and analyzed. Compared to neat marine diesel oil, W/O emulsions had higher combustion efficiencies, higher concentrations of O 2 and SO 2 , while gas temperatures were lowered and CO and NO x production was reduced. The addition of sodium sulfate decreased combustion efficiency and NO x concentration and increased O 2 , CO, and SO 2 concentrations.

Influences of vanadium compound on burning characteristics of emulsified marine fuel oil C

Abstract Vanadium is one of the most significant trace elements in heavy fuel oils. While most previous studies emphasize its effects on the high-temperature corrosion of power-plant materials, the understanding of the basic combustion characteristics influenced by the vanadium content in fuel oils is still rather limited. The influences of the controlling factors, such as water-to-oil ratio, amount of emulsifying agent, and content of vanadium pentoxide on the burning characteristics of marine heavy No.6 fuel oil are thus investigated in this experimental study by using a suspended droplet approach. It is shown that the ignition delay, degree of micro-explosion, burning time, and flame length are affected by those factors to various extents. Increase of the water-to-oil ratio might enhance the micro-explosion phenomenon while the addition of an appropriate amount of the emulsifying agent Span-80 promotes the homogeneity of micro-water-droplets over their oil base, leading to alterations of the heated droplet characteristics of the emulsions. However, the existence of V 2 O 5 in a fuel oil would result in deterioration of burning quality.

Emission characteristics of marine furnaces burned at varying inlet air temperatures and humidity

Abstract Marine power plants are frequently operated under varying atmospheric air temperature and humidity conditions. The effects of inlet air temperatures and humidity of marine furnaces such as incinerators and boilers thus attract much research interest. An industrial furnace incorporated with an automatic burner was employed to experimentally investigate the influences of the inlet air temperature and humidity on the emission characteristics. The inlet air humidity and temperature were adjusted using an air-conditioning machine to preset values before being admitted into the burner. ASTM No. 2D diesel oil was atomized, mixed with the inlet air and burned inside the industrial furnace. Eight small rectangular slots were cut on the upper side of the furnace to allow gas analyzer and thermocouple probes to be inserted into the furnace center to measure the axial variations in the gas temperature, burning efficiency and burning gas compositions such as NO x , SO 2 , CO. The experimental results show that the O 2 and NOx emission concentrations decreased while the CO 2 emission concentration and burning efficiency increased with either increasing inlet air humidity or temperature.

Emissions from an oil‐fired furnace burning MgO containing fuel oils

Abstract Low‐grade heavy oils are generally used as fuel oils for combustion systems of industrial or marine power‐plants such as boilers, furnaces, diesel engines, etc. for the pursuit of fuel economy. However, the burning of those fuel oils containing various organic or inorganic compounds of impurities in fuel ash leads to the formation of various very complex oxidation products in the burnt gas, resulting in the deterioration of atmospheric air quality and serious corrosion failures of construction materials. To combat the corrosion problems, some chemical agents such as MgO or CaO are considered as possible corrosion inhibitors. The MgO or CaO additive would react with other metallic compounds in fuel ash to form flying burnt salt with high melting point and adhere to the metal surface, consequently resulting in a decrease of the corrosion rate. In contrast to the understanding of MgO on the corrosion mechanism, the investigation of MgO on the emission characteristics of combustion systems is still r...

Influences of calcium oxide content in marine fuel oil on emission characteristics of marine furnaces under varying humidity and temperature of the inlet air.

Abstract A marine furnace made of stainless steel, combined with an automatic small-size oil-fired burner, was used to experimentally investigate the influences of calcium oxide content in fuel oil on the combustion and emission characteristics under varying temperatures and humidity of the inlet air. Marine fuel oil generally contains various extents of metallic oxides such as CaO, Fe2O3, V2O5, etc which might affect its burning properties. In this study, an air-conditioner was used to adjust the humidity and temperatures of the inlet air to preset values prior to entering the burner. The adjusted inlet air atomized the marine diesel oil A containing a calcium oxide compound, to form a heterogeneous reactant mixture. The reactant mixture was thereafter ignited by a high-voltage electrode in the burner and burned within the marine furnace. The probes of a gas analyzer, H2S analyzer and a K-type thermocouple were inserted into the radial positions of the furnace through the eight rectangular slots which were cut in the upper side of the furnace. The experimental results showed that an increase of either humidity or temperature of the inlet air caused the promotion of the reaction rate of the fuel. The existence of calcium oxide compound in the diesel fuel also facilitated the oxidation reaction in the combustion chamber. The addition of CaO in the diesel fuel under the conditions of higher temperature or higher relative humidity of the inlet air produced the following: higher concentrations of CO2, SO2, and H2S emissions, an increased burning efficiency, a lowered O2 level, production of excess air and NOx emissions as well as a lower thermal loss and a lower burning gas temperature, as compared with the conditions of a lower temperature or a lower humidity of the inlet air. In addition, the burning of diesel fuel with added CaO compound caused a large variation in the burning efficiency, thermal loss, plus CO2, O2, and excess air emissions between the conditions of higher temperature/higher humidity and lower temperature/lower humidity inlet air compared with no CaO addition in the fuel. Moreover, the burning efficiency and the concentrations of excess air and O2 emissions increased, while the thermal loss, burning gas temperature and H2S, SO2, NOx, and CO2 emissions decreased with the increase of the axial distance from the measured location to the burner nozzle.

Influences of fuel sulfur content on diesel engine emission characteristics under varying temperature and humidity of inlet air

Abstract The influences of the sulfur content of diesel oils on the emission characteristics of a diesel engine were systematically investigated in this study. The temperature and humidity of the inlet air, engine output torque, speed were also varied accordingly. The sulfur content was ranged from 0.3 to 0.85 wt% while engine output torque from 0 to 10 kg‐m, and speed from 1000 to 2000 rpm. The intake air temperature and relative humidity were set at 20 °C & 40 °C and 50%RH & 90%RH, respectively. A four‐cylinder diesel engine with a displacement volume of 3856 cc associated with a computerized engine data acquisition system was employed to observe and measure the engine performance under varying operating conditions. The temperature and humidity of intake air were adjusted by an inlet‐air temperature / humidity conditioning system. A mechanically stirring machine was used to mix the diesel fuel oil and sulfur compound homogeneously. This study shows that the increase of the sulfur content would enhance t...