This paper presents characteristics of a new catalytic converter (catco) to be used for natural g... more This paper presents characteristics of a new catalytic converter (catco) to be used for natural gas fuelled engine. The catco were developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO 2) and cobalt oxide (CoO) with wire mesh substrate. Both of the catalyst materials (such as TiO 2 and CoO) are inexpensive in comparison with conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metals are now identified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that the TiO 2 /CoO based catalytic converter and a new natural gas engine such as compressed natural gas (CNG) direct injection (DI) engine were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM catco) was tested for comparison purposes. The OEM catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO 2 /CoO based catalytic converter are 93%, 89% and 82% for NO x , CO and HC emissions respectively. It is calculated that the TiO 2 /CoO based catalytic converter reduces 24%, 41% and 40% higher NO x , CO and HC emissions in comparison to OEM catco respectively. The objective of this paper is to develop a low-cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low-cost catalytic converter development characteristics and CNGDI engine test results have been presented with discussions.
In recent years, the type of combustion occurred within engine cylinder plays an important role d... more In recent years, the type of combustion occurred within engine cylinder plays an important role determiningthe performance and emissions. In the present study, the computational investigation was performed in order tocompare characteristics of homogeneous and stratified combustion in a compressed natural gas direct injection engine.The numerical simulation was performed for single cylinder of the 1.6-liter engine running at wide open throttle at2000 rpm and 4000 rpm, accounting for medium and high loads for light-duty vehicle. The results of ComputationalFluid Dynamic (CFD) shows that calculated data of homogeneous combustion are in good agreement with theexperiment data obtained from previous work single-cylinder engine. Parametric studies are then conducted to addresseffect of some parameters on engine performance. Important parameters analysed include cylinder pressure, enginepower, mass fraction burned, CO, CO2 and NO emissions. It is found that homogeneous combustion has an adv...
WSEAS Transactions on Mathematics archive, Apr 1, 2008
Off-grid settlements require efficient, reliable and cost-effective renewable energy as alternati... more Off-grid settlements require efficient, reliable and cost-effective renewable energy as alternative to the power supplied by diesel generator. Techno-economic analysis is required to find the optimum renewable energy system in the long run. This paper reviews the application of genetic algorithms in optimization of hybrid system consisting of pico hydro system, solar photovoltaic modules, diesel generator and battery sets. It is intended to maximize the use of renewable system while limiting the use of diesel generator. Daily load demand is assumed constant for derivation of annual load. Power derived from the hybrid should be able to meet the demand. Local weather data is used and analyzed to assess the technical and economic viability of utilizing the hybrid system. Optimization of the system will be based on the component sizing and the operational strategy. Genetic algorithms programming is used to evaluate both conditions in minimizing the total net present cost for optimum configuration. Manufacturer data for the hybrid components is used in calculation of sizing to represent actual power derivation. Several operation strategies will be considered while forming the vectors for optimum strategy. Random selection of sizing and strategy is used to initiate the solution for the problem which will have the lowest total net present cost. Sensitivity analysis is also performed to optimize the system at different conditions.
The preparation of air–fuel mixture to achieve improved performance, efnamics. In this study, the... more The preparation of air–fuel mixture to achieve improved performance, efnamics. In this study, the effects of mixtures of hydrogen and compressed natural gas (CNG) on a spark ignition engine are numerically considered. This article presents the results of a direct-injection engine using methane– hydrogen mixtures containing 0 and 15 vol.% H 2 . The results show that the percentage of hydrogen in the CNG increases the burning velocity of CNG and reduces the optimal ignition timing to obtain the maximum peak pressure of an engine running with a blend of hydrogen and CNG. With hydrogen addition to natural gas, the peak heat release rates increase. For 15% hydrogen, the maximum values at crank angles (CAs) for in-cylinder temperature and heat release rate are achieved at 8° CA, and the maximum temperature diference is approximately 150 K . Port injection gasoline is converted into direct injection by CNG fuel in this engine.
Abstract This study investigates the effect of various injection timings on the performance and e... more Abstract This study investigates the effect of various injection timings on the performance and emissions of stratified combustion compressed natural-gas direct injection. The engine of 1.6 l, spark ignition, four cylinders fuelled with compressed natural gas was tested. The engine test bed using Kronos software and the exhaust emission were recorded using portable exhaust gas analyser Kane-May. All tests were occurred under wide throttle open with various injection timings (EOI 120, EOI 180, EOI 300, EOI 360) BTDC. Results show high power, torque and brake mean effective pressure (BMEP) at 120 BTDC. The lowest brake specific fuel consumption (BSFC) is at 120 BTDC. Lambda is shown higher than one, which is mean lean mixture air-fuel. Carbon monoxide (CO) emission is low at 360 BTDC at low speeds but at high speed, it was low at 120 BTDC. Carbon dioxide (CO2) emission was high at 120 BTDC on the high engine speeds. The lowest (NO) and (HC) were founded at 120 BTDC. However, the combustion pressure and the PV were recorded for all injection timings under various engine speeds.
International Journal of Automotive and Mechanical Engineering
In this work, the design and simulation of a cylinder head with compressed natural gas direct inj... more In this work, the design and simulation of a cylinder head with compressed natural gas direct injection (CNGDI) is studied based on finite element analysis. The analysis was carried out to simulate the stress and displacement for the cylinder head at various engine speeds in the range of between 1000 and 5400 rpm. The design is developed using CATIA V5, and simulated using MSC Nastran, then pre-and post-processed by MSC Patran. Based on the simulation results, an improved design for the CNGDI cylinder head was achieved. The stress and displacement analysis highlighted several areas of interest, and the maximum stress for the modified model of 56.16 MPa was found not to exceed the allowable compressive yield strength of the material used (aluminum alloy A356-T6), of 172 MPa. The maximum displacement for the modified model, which was 0.00972 mm, was below the lowest displacement limit of 0.032 mm. For the modified model, the strength was improved by about 1.72%, and the displacement d...
Cascade aerators are normally used in water treatment for recreational lakes and fish raring pond... more Cascade aerators are normally used in water treatment for recreational lakes and fish raring ponds and also in the post aeration of drinking water supply, which generally have quite low efficiencies with dissolved oxygen serves as healthcare element in the human body when consumed as drinking water. The objective of this research is to develop and design an efficient cascade aerator for treated water based on the plunging water jet. The development of the cascade aerator in the past since the industrial revolution is studied and analyzed in order to identify the relationships between the properties of the cascade aerator with the important parameters such as water potential energy, water flow-rate, conditions of atmospheric air, diffusivity and dissolvability of air-water, saturation level of dissolved oxygen, water temperature and water pressure. The geometrical parameters involved are the height of plunging of water jet, angle of plunging water jet with respect to horizontal plane, size of water jet nozzle pipe, height of cascading, depth of water in lower tank and depth of water in upper tank. In the first stage, research is focused on identifying the parameters that influence the performance of a cascade aerator by means of theoretical study and by referring to the finding of the earlier research works. The relationship equation between height of cascading H and the ratio of dissolved oxygen deficit, R and also the other parameters consisting of temperature, T , water quality coefficient, a, geometrical parameters coefficient, b for a 4 stage weir based cascade aerator which had been developed by Barrett, relating height of cascading H which is proportional to the ratio of Oxygen deficit and inversely proportional to the temperature, is used as the basis for deriving the equations for the new design of cascade aerator based on the plunging water jet. While the general aeration equation in term of dissolved oxygen gradient proportional to the overall aeration coefficient value of the aerator, K L a is used as the basis to determine the coefficient of oxygen mass transfer of the whole cascade aerator. The following stage of research works is to determine the optimum points of test parameters in an empirical experiment by collecting data from a single stage, single nozzle model of cascade aerator based on the dissolved oxygen concentration values for several nozzle pipe's internal diameter, of 10 mm, 14 mm, 18mm, 20 mm. While the angle of plunging jet is varied by changing the angular position of the nozzle so as to produce angle of impact, is tested at 30 o , 45 o , 60 o , 75 o and 90 o. The water jet plunging height, H is tested at several vertical distances of 170 mm, 280 mm, 330 mm, 400 mm, and 500 mm. The depth of water in the lower tank, d t is tested at several depth of 145 mm, 175 mm, 200 mm, 245 mm and 280 mm. While the depth of water in the upper tank, d a is tested at several depth of 410 mm, 450 mm, 510 mm, 580 mm and 700 mm. The results of the experiment found that the optimum height of plunging of the water jet, H is at 330 mm and the optimum angle of water jet, and with respect to the horizontal plane are 50 o at inception point and 56 o at impact point at the nozzle and at the lower tank water surface respectively. Optimum diameter of the plunging jet is 19 mm while the optimum depth of lower water tank is 190 mm and finally the optimum depth of upper water in the upper tank is at 515 mm. The results obtained in experimental study is then validated by using computer simulation program, CFD (FLUENT) and test on the prototype based on the optimum parameters. The optimum geometrical parameters obtained and validated above are used as the basis of the new design of an efficient plunging water jet based cascade aerator for the post aeration process of treated water supply.
With increasing concerns about energy shortages and environmental protection, research on improvi... more With increasing concerns about energy shortages and environmental protection, research on improving engine fuel economy and reducing exhaust emissions has become a major research focus in combustion and engine development. Also, with conversion a conventional port fuel injection engine to direct injection (DI) and using alternative fuels, air/fuel mixture can be controlled and the engine is allowed to operate with very lean condition. With appropriate control of the air to fuel ratio gradient, the combustion process allows clean and controlled combustion, resulting in future improvement in fuel economy and emission control. In this study, the effects of mixtures of hydrogen and compressed natural gas (CNG) on a spark ignition engine are numerically considered. This article presents the results of a direct-injection engine using methanehydrogen mixtures containing H 2 between 0% and 30% by volume. The result shows that the percentage of hydrogen in the CNG increases the burning velocity of CNG and reduces the optimal ignition timing to obtain the maximum peak pressure of an engine running with a blend of hydrogen and CNG. With hydrogen addition to natural gas, the peak heat release rates increase. For 20% hydrogen, the maximum values at crank angles (CAs) for in-cylinder temperature and heat release rate are achieved at 6° CA, and the maximum temperature is approximately 150 K. also it can be seen that torque and power was increased with adding hydrogen to natural gas and it is about 3%. Port injection gasoline is converted into direct injection by CNG fuel in this engine.
Preparation of air-fuel mixture is considerably dependent on the fluid flow dynamics in order to ... more Preparation of air-fuel mixture is considerably dependent on the fluid flow dynamics in order to achieve improved performance, efficiency, and engine combustion in the appearance of flow. In this study, effects on a spark ignition engine of mixtures of hydrogen and compressed natural gas have been numerically considered. This article presents the results of a direct injection engine with mixtures of hydrogen in methane of 0, 7, and 15% by volume. The result shows that the percentage of hydrogen in the CNG increases the burning velocity of CNG and come down the optimal ignition timing to obtain the maximum peak pressure of the engine running with blending of hydrogen to CNG. With adding hydrogen to natural gas, the peak heat release rates increase. For 15% hydrogen, the maximum values at crank angles for in cylinder temperature and heat release rate achieved at 8 degree of CA and the maximum temperature is about 150 K. Port injection gasoline was converted into direct injection by compressed natural gas fuel in this engine.
International Journal of Renewable and Sustainable Energy, 2014
Conventional fossil fuel for combustion system, such as gasoline and petroleum have long been rec... more Conventional fossil fuel for combustion system, such as gasoline and petroleum have long been recognized as powerful energy source, however these have a number of problems related to emissions and energy security. The use of hydrogen blends with natural gas is a viable alternative to pure fossil fuels because of the expected reduction of the total pollutant emissions and increase of efficiency. Enhancement of chemical reaction with hydrogen addition is regarded as the increase of H, O and OH free radical mole fraction in the flame. Also in SI engines will move the lean limit to leaner mixture, increasing the combustion speed and temperature. Results show that the hydrogen has a catalyzing effect in the ignition of hydrocarbons with only a few percent addition of hydrogen by volume and by adding it to the pure natural gas (CNG) this difference in spark advance of the engine may be reduced, as a result of the higher flame speed of hydrogen. In this paper, we present the advances and development made on internal combustion engines which operate with mixture of hydrogen/CNG, doing more emphasis in the combustion process, ignition energy and injection systems. Also this paper mentions a comparison that experimental and numerical results match quite well expect for extremely fuel lean condition. The nozzle geometry has an important influence on injection process and combustion development and shows that degree of conicity can be evaluated for each nozzle by the K-Factor.
2010 2nd International Congress on Engineering Education, 2010
A survey was conducted to find the impact of quality of students and the experience gained throug... more A survey was conducted to find the impact of quality of students and the experience gained through international challenges outdoor project activities which involved the students of the UKM. The survey was done on the students that participated in the Shell Eco Marathon which was first organized in Malaysia and in Asia region. The objective is to find out whether the students have acquired creativity, self confidence, team work, good management and good communication through project and how the students work in team in achieving the goals of the project This brief analysis of the survey has shown that the response of the students on quality of good management, good communication and teamwork. There is some indication that project outdoor sports activities have create effective way to poster good management and communication among the team. However, on creativity and innovative thinking, the students have not acquired full creativity and innovative idea on transferring the academic knowledge applied into the project. The hard working effort has created integration among some races Malays and Chinese but the participation of Indian need to be improved. Various qualities, such as cooperation, the self confidence, yearning to be the champion and good leadership were discovered. The hard working effort and high commitment has been shown by the students to work together and having good leadership, good management and good communication. The creativity of the group is still need improvement This survey has also shown that the project generates healthy understanding amongst students, for integration and exchanges of views for environmental conservation and future sustainable of human life in this region as well as in the whole world. The result of the survey clearly support the positive thinking of the students to demonstrate the good management and good communication amongst the group member and that what takes them to be successful in real life.
Performance of the absorption cooling system is still a challenge due to the coefficient of perfo... more Performance of the absorption cooling system is still a challenge due to the coefficient of performance (COP) that is generally poor when compared with the conventional vapor compression cycle. High solar radiation in hot climates is usually associated with high ambient temperature and consequently peak cooling demand. Absorption cooling cycles can be powered by solar but the performance is limited by heat source temperature (solar collector) and high ambient temperature that can affect the condensation process. Efficiency enhancement of the system components is essential to increase the COP of the system. A modification in the combined absorption-ejector cooling system is adopted. Adding a removable flash tank between the condenser and evaporator could improve entrainment ratio of the ejector, along with improving the cooling effect inside the evaporator. A computer simulation program is developed to evaluate the performance of the modified combined cycle using aquaammonia (NH3-H2O) refrigerant. The performance of the proposed combined cooling cycle is compared with basic absorption, and combined absorption-ejector cooling cycles. Results showed a significant improvement in the COP of the modified cycle at different operating conditions. Cooling effect and capacity of the evaporator is enhanced due to the reduction of flash gas delivered to the evaporator. Furthermore, the flash tank optimized the ejector entertainment ratio and consequently increasing the condenser pressure. This optimization will enable the system to perform well in hot climates where the condenser efficiency is limited by ambient temperature.
ABSTRACT A study was carried out on the new design of fuel injectors for Compressed Natural Gas D... more ABSTRACT A study was carried out on the new design of fuel injectors for Compressed Natural Gas Direct Injection (CNGDI) engine. There are two injectors designed with 30° and 70° spray angle was developed and tested. The tests on the injectors were carried out using Single Cylinder Research Engine SCRE with compression ratio of 14:1. The SCRE test bed used computerized data acquisition system. There are two main parameters for the selection of the best injector i.e. the spray angle (30° and 70°) and the operating pressure is set at 2.0 MPa. From the study, the engine performance and the emission were recorded from the test. The results indicated that the injector with 70° spray angle achieved higher performance than the other injector.
ABSTRACT A new design of fuel system for CNG engine with direct injection (CNGDI) was developed f... more ABSTRACT A new design of fuel system for CNG engine with direct injection (CNGDI) was developed for a demonstration project. The development of the fuel system was done on the engine with cylinder head modifications, for fuel injector and spark plug openings included in the new cylinder head. The piston was also redesigned for higher compression ratio. The fuel rails and the regulators are also designed for the direct injection system operating at higher pressure about 2.0 MPa. The control of the injection timing for the direct injectors are also controlled by the Electronic Control Unit specially designed for DI by another group project. The injectors are selected after testing with the various injection pressures and spray angles. For the best performance of the high-pressure system, selection is made from the tests on single cylinder research engine (SCRE). The components in the fuel system have to be of higher quality and complied with codes and standards to secure the safety of engine for high-pressure operation. The results of the CNGDI have shown that better power output is produced and better emissions were achieved compared to the aspirated CNG engine.
This paper presents characteristics of a new catalytic converter (catco) to be used for natural g... more This paper presents characteristics of a new catalytic converter (catco) to be used for natural gas fuelled engine. The catco were developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO 2) and cobalt oxide (CoO) with wire mesh substrate. Both of the catalyst materials (such as TiO 2 and CoO) are inexpensive in comparison with conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metals are now identified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that the TiO 2 /CoO based catalytic converter and a new natural gas engine such as compressed natural gas (CNG) direct injection (DI) engine were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM catco) was tested for comparison purposes. The OEM catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO 2 /CoO based catalytic converter are 93%, 89% and 82% for NO x , CO and HC emissions respectively. It is calculated that the TiO 2 /CoO based catalytic converter reduces 24%, 41% and 40% higher NO x , CO and HC emissions in comparison to OEM catco respectively. The objective of this paper is to develop a low-cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low-cost catalytic converter development characteristics and CNGDI engine test results have been presented with discussions.
In recent years, the type of combustion occurred within engine cylinder plays an important role d... more In recent years, the type of combustion occurred within engine cylinder plays an important role determiningthe performance and emissions. In the present study, the computational investigation was performed in order tocompare characteristics of homogeneous and stratified combustion in a compressed natural gas direct injection engine.The numerical simulation was performed for single cylinder of the 1.6-liter engine running at wide open throttle at2000 rpm and 4000 rpm, accounting for medium and high loads for light-duty vehicle. The results of ComputationalFluid Dynamic (CFD) shows that calculated data of homogeneous combustion are in good agreement with theexperiment data obtained from previous work single-cylinder engine. Parametric studies are then conducted to addresseffect of some parameters on engine performance. Important parameters analysed include cylinder pressure, enginepower, mass fraction burned, CO, CO2 and NO emissions. It is found that homogeneous combustion has an adv...
WSEAS Transactions on Mathematics archive, Apr 1, 2008
Off-grid settlements require efficient, reliable and cost-effective renewable energy as alternati... more Off-grid settlements require efficient, reliable and cost-effective renewable energy as alternative to the power supplied by diesel generator. Techno-economic analysis is required to find the optimum renewable energy system in the long run. This paper reviews the application of genetic algorithms in optimization of hybrid system consisting of pico hydro system, solar photovoltaic modules, diesel generator and battery sets. It is intended to maximize the use of renewable system while limiting the use of diesel generator. Daily load demand is assumed constant for derivation of annual load. Power derived from the hybrid should be able to meet the demand. Local weather data is used and analyzed to assess the technical and economic viability of utilizing the hybrid system. Optimization of the system will be based on the component sizing and the operational strategy. Genetic algorithms programming is used to evaluate both conditions in minimizing the total net present cost for optimum configuration. Manufacturer data for the hybrid components is used in calculation of sizing to represent actual power derivation. Several operation strategies will be considered while forming the vectors for optimum strategy. Random selection of sizing and strategy is used to initiate the solution for the problem which will have the lowest total net present cost. Sensitivity analysis is also performed to optimize the system at different conditions.
The preparation of air–fuel mixture to achieve improved performance, efnamics. In this study, the... more The preparation of air–fuel mixture to achieve improved performance, efnamics. In this study, the effects of mixtures of hydrogen and compressed natural gas (CNG) on a spark ignition engine are numerically considered. This article presents the results of a direct-injection engine using methane– hydrogen mixtures containing 0 and 15 vol.% H 2 . The results show that the percentage of hydrogen in the CNG increases the burning velocity of CNG and reduces the optimal ignition timing to obtain the maximum peak pressure of an engine running with a blend of hydrogen and CNG. With hydrogen addition to natural gas, the peak heat release rates increase. For 15% hydrogen, the maximum values at crank angles (CAs) for in-cylinder temperature and heat release rate are achieved at 8° CA, and the maximum temperature diference is approximately 150 K . Port injection gasoline is converted into direct injection by CNG fuel in this engine.
Abstract This study investigates the effect of various injection timings on the performance and e... more Abstract This study investigates the effect of various injection timings on the performance and emissions of stratified combustion compressed natural-gas direct injection. The engine of 1.6 l, spark ignition, four cylinders fuelled with compressed natural gas was tested. The engine test bed using Kronos software and the exhaust emission were recorded using portable exhaust gas analyser Kane-May. All tests were occurred under wide throttle open with various injection timings (EOI 120, EOI 180, EOI 300, EOI 360) BTDC. Results show high power, torque and brake mean effective pressure (BMEP) at 120 BTDC. The lowest brake specific fuel consumption (BSFC) is at 120 BTDC. Lambda is shown higher than one, which is mean lean mixture air-fuel. Carbon monoxide (CO) emission is low at 360 BTDC at low speeds but at high speed, it was low at 120 BTDC. Carbon dioxide (CO2) emission was high at 120 BTDC on the high engine speeds. The lowest (NO) and (HC) were founded at 120 BTDC. However, the combustion pressure and the PV were recorded for all injection timings under various engine speeds.
International Journal of Automotive and Mechanical Engineering
In this work, the design and simulation of a cylinder head with compressed natural gas direct inj... more In this work, the design and simulation of a cylinder head with compressed natural gas direct injection (CNGDI) is studied based on finite element analysis. The analysis was carried out to simulate the stress and displacement for the cylinder head at various engine speeds in the range of between 1000 and 5400 rpm. The design is developed using CATIA V5, and simulated using MSC Nastran, then pre-and post-processed by MSC Patran. Based on the simulation results, an improved design for the CNGDI cylinder head was achieved. The stress and displacement analysis highlighted several areas of interest, and the maximum stress for the modified model of 56.16 MPa was found not to exceed the allowable compressive yield strength of the material used (aluminum alloy A356-T6), of 172 MPa. The maximum displacement for the modified model, which was 0.00972 mm, was below the lowest displacement limit of 0.032 mm. For the modified model, the strength was improved by about 1.72%, and the displacement d...
Cascade aerators are normally used in water treatment for recreational lakes and fish raring pond... more Cascade aerators are normally used in water treatment for recreational lakes and fish raring ponds and also in the post aeration of drinking water supply, which generally have quite low efficiencies with dissolved oxygen serves as healthcare element in the human body when consumed as drinking water. The objective of this research is to develop and design an efficient cascade aerator for treated water based on the plunging water jet. The development of the cascade aerator in the past since the industrial revolution is studied and analyzed in order to identify the relationships between the properties of the cascade aerator with the important parameters such as water potential energy, water flow-rate, conditions of atmospheric air, diffusivity and dissolvability of air-water, saturation level of dissolved oxygen, water temperature and water pressure. The geometrical parameters involved are the height of plunging of water jet, angle of plunging water jet with respect to horizontal plane, size of water jet nozzle pipe, height of cascading, depth of water in lower tank and depth of water in upper tank. In the first stage, research is focused on identifying the parameters that influence the performance of a cascade aerator by means of theoretical study and by referring to the finding of the earlier research works. The relationship equation between height of cascading H and the ratio of dissolved oxygen deficit, R and also the other parameters consisting of temperature, T , water quality coefficient, a, geometrical parameters coefficient, b for a 4 stage weir based cascade aerator which had been developed by Barrett, relating height of cascading H which is proportional to the ratio of Oxygen deficit and inversely proportional to the temperature, is used as the basis for deriving the equations for the new design of cascade aerator based on the plunging water jet. While the general aeration equation in term of dissolved oxygen gradient proportional to the overall aeration coefficient value of the aerator, K L a is used as the basis to determine the coefficient of oxygen mass transfer of the whole cascade aerator. The following stage of research works is to determine the optimum points of test parameters in an empirical experiment by collecting data from a single stage, single nozzle model of cascade aerator based on the dissolved oxygen concentration values for several nozzle pipe's internal diameter, of 10 mm, 14 mm, 18mm, 20 mm. While the angle of plunging jet is varied by changing the angular position of the nozzle so as to produce angle of impact, is tested at 30 o , 45 o , 60 o , 75 o and 90 o. The water jet plunging height, H is tested at several vertical distances of 170 mm, 280 mm, 330 mm, 400 mm, and 500 mm. The depth of water in the lower tank, d t is tested at several depth of 145 mm, 175 mm, 200 mm, 245 mm and 280 mm. While the depth of water in the upper tank, d a is tested at several depth of 410 mm, 450 mm, 510 mm, 580 mm and 700 mm. The results of the experiment found that the optimum height of plunging of the water jet, H is at 330 mm and the optimum angle of water jet, and with respect to the horizontal plane are 50 o at inception point and 56 o at impact point at the nozzle and at the lower tank water surface respectively. Optimum diameter of the plunging jet is 19 mm while the optimum depth of lower water tank is 190 mm and finally the optimum depth of upper water in the upper tank is at 515 mm. The results obtained in experimental study is then validated by using computer simulation program, CFD (FLUENT) and test on the prototype based on the optimum parameters. The optimum geometrical parameters obtained and validated above are used as the basis of the new design of an efficient plunging water jet based cascade aerator for the post aeration process of treated water supply.
With increasing concerns about energy shortages and environmental protection, research on improvi... more With increasing concerns about energy shortages and environmental protection, research on improving engine fuel economy and reducing exhaust emissions has become a major research focus in combustion and engine development. Also, with conversion a conventional port fuel injection engine to direct injection (DI) and using alternative fuels, air/fuel mixture can be controlled and the engine is allowed to operate with very lean condition. With appropriate control of the air to fuel ratio gradient, the combustion process allows clean and controlled combustion, resulting in future improvement in fuel economy and emission control. In this study, the effects of mixtures of hydrogen and compressed natural gas (CNG) on a spark ignition engine are numerically considered. This article presents the results of a direct-injection engine using methanehydrogen mixtures containing H 2 between 0% and 30% by volume. The result shows that the percentage of hydrogen in the CNG increases the burning velocity of CNG and reduces the optimal ignition timing to obtain the maximum peak pressure of an engine running with a blend of hydrogen and CNG. With hydrogen addition to natural gas, the peak heat release rates increase. For 20% hydrogen, the maximum values at crank angles (CAs) for in-cylinder temperature and heat release rate are achieved at 6° CA, and the maximum temperature is approximately 150 K. also it can be seen that torque and power was increased with adding hydrogen to natural gas and it is about 3%. Port injection gasoline is converted into direct injection by CNG fuel in this engine.
Preparation of air-fuel mixture is considerably dependent on the fluid flow dynamics in order to ... more Preparation of air-fuel mixture is considerably dependent on the fluid flow dynamics in order to achieve improved performance, efficiency, and engine combustion in the appearance of flow. In this study, effects on a spark ignition engine of mixtures of hydrogen and compressed natural gas have been numerically considered. This article presents the results of a direct injection engine with mixtures of hydrogen in methane of 0, 7, and 15% by volume. The result shows that the percentage of hydrogen in the CNG increases the burning velocity of CNG and come down the optimal ignition timing to obtain the maximum peak pressure of the engine running with blending of hydrogen to CNG. With adding hydrogen to natural gas, the peak heat release rates increase. For 15% hydrogen, the maximum values at crank angles for in cylinder temperature and heat release rate achieved at 8 degree of CA and the maximum temperature is about 150 K. Port injection gasoline was converted into direct injection by compressed natural gas fuel in this engine.
International Journal of Renewable and Sustainable Energy, 2014
Conventional fossil fuel for combustion system, such as gasoline and petroleum have long been rec... more Conventional fossil fuel for combustion system, such as gasoline and petroleum have long been recognized as powerful energy source, however these have a number of problems related to emissions and energy security. The use of hydrogen blends with natural gas is a viable alternative to pure fossil fuels because of the expected reduction of the total pollutant emissions and increase of efficiency. Enhancement of chemical reaction with hydrogen addition is regarded as the increase of H, O and OH free radical mole fraction in the flame. Also in SI engines will move the lean limit to leaner mixture, increasing the combustion speed and temperature. Results show that the hydrogen has a catalyzing effect in the ignition of hydrocarbons with only a few percent addition of hydrogen by volume and by adding it to the pure natural gas (CNG) this difference in spark advance of the engine may be reduced, as a result of the higher flame speed of hydrogen. In this paper, we present the advances and development made on internal combustion engines which operate with mixture of hydrogen/CNG, doing more emphasis in the combustion process, ignition energy and injection systems. Also this paper mentions a comparison that experimental and numerical results match quite well expect for extremely fuel lean condition. The nozzle geometry has an important influence on injection process and combustion development and shows that degree of conicity can be evaluated for each nozzle by the K-Factor.
2010 2nd International Congress on Engineering Education, 2010
A survey was conducted to find the impact of quality of students and the experience gained throug... more A survey was conducted to find the impact of quality of students and the experience gained through international challenges outdoor project activities which involved the students of the UKM. The survey was done on the students that participated in the Shell Eco Marathon which was first organized in Malaysia and in Asia region. The objective is to find out whether the students have acquired creativity, self confidence, team work, good management and good communication through project and how the students work in team in achieving the goals of the project This brief analysis of the survey has shown that the response of the students on quality of good management, good communication and teamwork. There is some indication that project outdoor sports activities have create effective way to poster good management and communication among the team. However, on creativity and innovative thinking, the students have not acquired full creativity and innovative idea on transferring the academic knowledge applied into the project. The hard working effort has created integration among some races Malays and Chinese but the participation of Indian need to be improved. Various qualities, such as cooperation, the self confidence, yearning to be the champion and good leadership were discovered. The hard working effort and high commitment has been shown by the students to work together and having good leadership, good management and good communication. The creativity of the group is still need improvement This survey has also shown that the project generates healthy understanding amongst students, for integration and exchanges of views for environmental conservation and future sustainable of human life in this region as well as in the whole world. The result of the survey clearly support the positive thinking of the students to demonstrate the good management and good communication amongst the group member and that what takes them to be successful in real life.
Performance of the absorption cooling system is still a challenge due to the coefficient of perfo... more Performance of the absorption cooling system is still a challenge due to the coefficient of performance (COP) that is generally poor when compared with the conventional vapor compression cycle. High solar radiation in hot climates is usually associated with high ambient temperature and consequently peak cooling demand. Absorption cooling cycles can be powered by solar but the performance is limited by heat source temperature (solar collector) and high ambient temperature that can affect the condensation process. Efficiency enhancement of the system components is essential to increase the COP of the system. A modification in the combined absorption-ejector cooling system is adopted. Adding a removable flash tank between the condenser and evaporator could improve entrainment ratio of the ejector, along with improving the cooling effect inside the evaporator. A computer simulation program is developed to evaluate the performance of the modified combined cycle using aquaammonia (NH3-H2O) refrigerant. The performance of the proposed combined cooling cycle is compared with basic absorption, and combined absorption-ejector cooling cycles. Results showed a significant improvement in the COP of the modified cycle at different operating conditions. Cooling effect and capacity of the evaporator is enhanced due to the reduction of flash gas delivered to the evaporator. Furthermore, the flash tank optimized the ejector entertainment ratio and consequently increasing the condenser pressure. This optimization will enable the system to perform well in hot climates where the condenser efficiency is limited by ambient temperature.
ABSTRACT A study was carried out on the new design of fuel injectors for Compressed Natural Gas D... more ABSTRACT A study was carried out on the new design of fuel injectors for Compressed Natural Gas Direct Injection (CNGDI) engine. There are two injectors designed with 30° and 70° spray angle was developed and tested. The tests on the injectors were carried out using Single Cylinder Research Engine SCRE with compression ratio of 14:1. The SCRE test bed used computerized data acquisition system. There are two main parameters for the selection of the best injector i.e. the spray angle (30° and 70°) and the operating pressure is set at 2.0 MPa. From the study, the engine performance and the emission were recorded from the test. The results indicated that the injector with 70° spray angle achieved higher performance than the other injector.
ABSTRACT A new design of fuel system for CNG engine with direct injection (CNGDI) was developed f... more ABSTRACT A new design of fuel system for CNG engine with direct injection (CNGDI) was developed for a demonstration project. The development of the fuel system was done on the engine with cylinder head modifications, for fuel injector and spark plug openings included in the new cylinder head. The piston was also redesigned for higher compression ratio. The fuel rails and the regulators are also designed for the direct injection system operating at higher pressure about 2.0 MPa. The control of the injection timing for the direct injectors are also controlled by the Electronic Control Unit specially designed for DI by another group project. The injectors are selected after testing with the various injection pressures and spray angles. For the best performance of the high-pressure system, selection is made from the tests on single cylinder research engine (SCRE). The components in the fuel system have to be of higher quality and complied with codes and standards to secure the safety of engine for high-pressure operation. The results of the CNGDI have shown that better power output is produced and better emissions were achieved compared to the aspirated CNG engine.
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