Applied Mechanics and Materials Vols. 773-774

Abstract: Effect of radiation on free convection on heated horizontal circular has been investigated. The cylinder is fixed and immersed in a stationary fluid, in which the temperature is uniformly heated about the temperature of the surrounding fluid. The governing equation are transformed into dimensionless non-linear of partial differential equations and solved numerically by employing a finite difference method. An implicit finite difference scheme of Crank Nicolson method is used to analyze the results. This study determine the effects of radiation parameter, heat generation parameter, and the Prandtl number, , on the temperature and velocity profiles. The results of the local heat transfer and skin-friction coefficient in the presence of radiation for some selected values of Prandtl number and heat generation parameter have shown graphically.Keywords: Radiation; free convection; heated circular cylinder; heat generation.

Abstract: Sufficient air insert by reduced liquid in flashing propellants are required to produce fine droplet size with symmetrical spray in an aerosol atomiser without swirling design. It is called novel matched valve-actuator with two-fluid fine nozzle. Two-fluid fine nozzle design is an arrangement between air-assist atomiser insert, air blast and effervescent atomiser insert. However, 50% fill ratio and 9bar on pressure can with a currently acceptable become “Benchmark Objective” in this research. The results shows a few measurement with the same volume flow rate and variable flow rate of two fluids atomiser which have been taken in the experimental. 50 ml/min for liquid flow rate and 150ml/min flow rate of insert gas could reduce droplet size less than 70μm SMD by modifying the insert to promote greater cone angle and droplet size distribution with differences on quantity of air, liquid supply and the atomising velocity. Validation of two-fluid fine nozzle results is also recommended to be carried out and compared with the experiment results which related to turbulence kinetic energy with the atomiser insert and droplet size. Further researches are concentrating on modelling droplet breakup downstream of the atomiser insert.Keywordaerosol atomiser, two-fluid fine nozzle, fill ratio, droplet size.

Abstract: In order to increase the thermal efficiency of a gas turbine, the operating temperature has to be increased. This increment may cause the material of the blade to melt. Film cooling is a good option to solve this problem. Various studies has been done on film cooling include the shallow hole and sister holes. The present study focused on an experimental of film cooling effectiveness on shallow hole of 20° with upstream sister holes with 3 blowing ratios which are 1.0, 15 and 2.0. The result showed significant improvement compared to shallow hole of 35°. The optimum blowing ratio is 1.5. Smaller shallow angle and upstream sister holes reduce the jet lifting effect of the secondary air flow. Future study can be done on shallow hole of shallow angle and blowing ratio around 1.5 in order to further improve the film cooling effectiveness.

Abstract: Numerical study using ANSYS Fluent is conducted to investigate the effects of louver angle on pressure drop and heat transfer of a heat exchanger. Flow simulations are conducted on 3D modeling of multi stacks louvered fins at three different parameters of louver angles which are 22.0o, 25.5o and 29.0o with Reynolds number ranging from 200 to 1000. These Reynolds numbers are based on louver pitch and fin pitch. The flow temperature is set at 300K which is the room temperature, while temperature of louver fin is set at 400K. The results show that Reynolds number based on fin pitch 2.02 mm and louver angle of 22.0o generate higher performance of heat exchanger compared to louver pitch of 1.40 mm and the other louver angles. Therefore, configuration of Reynolds number based on fin pitch 2.02 mm and louver angle 22.0o is preferred to be adopted in the design process of heat exchanger.

Abstract: In recent years, minimum quantity lubrication (MQL) machining is regarded as a promising method for reducing machining cost and cutting fluid, while improving cutting performance. However the effectiveness and the working principle of MQL are still questionable with very few explanations provided. The aim of this study is to determine the optimum distance between the nozzle and tool tip and appropriate flow pattern of the mist flow for minimum quantity lubricant using Particle Image Velocimetry (PIV) and Computer Fluid Dynamic (CFD) for optimizing the spraying conditions thus reducing the lubricant consumption. The spray from the nozzle with outlet diameter of 2.5mm is analysed using Particle Image Velocimetry (PIV) to measure the mist flow velocity and identify the flow pattern. The input pressure of 0.2, 0.3 and 0.4MPa will be discharged throughout the experiment. Higher pressure produce more mass flow rate which helps in reducing the cutting force and cutting temperature efficiently and prolong tool life. Thus the appropriate distance can reduce lubricant consumption and increase the cooling and lubricating ability with best nozzle position. The applied distance increases the efficiencies of MQL applied during machining process.

Abstract: A prototype aluminium microreactor for steam methane reforming process to produce hydrogen syngas, with parallel flow microchannels was developed. The microreactor was heated up to 400°C using a Bunsen burner at distance of 10mm below it surface. Whereby two condition of burner open flow which are 1/3 and 2/3 took place in order to investigate its heating effect on outlet stream temperature. From the results, show that both Bunsen burner flow slightly show the same tendency of increasing and decreasing state, which indicated the optimum point of heat transfer to the systems for a cycle. But, the 2/3 opening Bunsen burner flow give the reliable contact reaction time at minimum operating condition of 400 °C and 1 bar compare to 1/3 opening. This is due to its ability for lays above the set temperature point with longest duration time. From this results can conclude that, the relationship between contact flame area and microreactor surface on outlet flow temperature had been developed. The outlet stream temperature is proportional to the Bunsen burner opening, based on biggest area of flame contact yield the highest optimum temperature point with longest reaction time.

Abstract: In this paper, an experimental study evaluating the effect of exhaust gas recirculation (EGR) and liquefied petroleum gas (LPG) onboard systems attached to a single cylinder DI diesel engine running with diesel is presented. Tests were performed at the minimum (1400 rpm) and maximum engine speeds (4100 rpm). The engine were tested under four different operating modes mainly; (a) standard test condition, (b) engine with EGR system, (c) engine with LPG system and (d) the engine with EGR and LPG onboard systems. Parameters that been measured during the tests are percentage of oxygen (O₂) content, carbon monoxide (CO) emissions, carbon dioxide (CO₂) and unburned hydrocarbon (UHC) emissions. Results show for the exhaust emissions, the engine with LPG onboard system emits higher CO and UHC emissions for both engine speeds. According to the experimental results it can be concluded that the use of EGR system increased the exhaust gas temperature and CO₂ emissions. While the engine with EGR and LPG onboard systems have influenced much on the increase in CO and UHC emissions for both engine speeds.

Abstract: Particulate matter (PM) is one of the major pollutants emitted by diesel engine which have adverse effects on human health. Accordingly, many researches have been done to find alternative fuels that are clean and efficient. Biodiesel is preferred as an alternative source for diesel engine which produces lower PM than diesel fuel. However, the manufacturing cost of biodiesel from vegetable oil is expensive. Therefore, using waste cooking oil (WCO) for biodiesel would be more economical and sustainable solution. The characteristics of direct injection diesel engine in term of the PM have been investigated experimentally in this study. The experiments were conducted using single cylinder diesel engine with different speed (1200 rpm, 1500 rpm, 1800 rpm, 2100 rpm, 2400 rpm) at constant load. PM emission of WCO B100 and diesel fuel was compared and the effect of PM components such as soluble organic fraction (SOF) and soot were studied. The result showed WCO B100 reduces the PM emission at all engine speed. Furthermore, both fuels showed highest reduction of PM concentration at moderate engine speed of 1500 rpm.

Abstract: The depletion of fossil fuels as well as the rises of greenhouse gases had caused most government worldwide to follow the international energy policies for the use of biodiesel. One of the economical sources for biodiesel production is waste cooking oil. The use of waste cooking oil is more sustainable if they can perform similarly to conventional diesel fuel. This paper deals with the experimental study carried out to evaluate the engine performance and exhaust emission of diesel engine operated by biodiesel from waste cooking oil at various engine speed. The biodiesel used are known as B5, which contains of 5% of waste cooking oil and 95% of diesel fuel. The other one is B20, which contains of 20% of waste cooking oil plus 80% of diesel. Diesel was used as a comparison purposes. The results show that power and torque for B5 give the closest trend to diesel. In terms of heat release, diesel still dominates the highest value compared to B5 and B20. For exhaust emission, B5 and B20 showed improvement in the reduction of NO_x and PM.

Abstract: Bio-additive is biodegradable and produces less air pollution thus significant for replacing the limited fossil fuels and reducing threats to the environment from exhaust emissions and global warming. Instead, the bio-additives can remarkably improve the fuel economy SI engine while operating on all kinds of fuel. Some of the bio-additive has the ability to reduce the total CO₂ emission from internal petrol engine. This review paper focuses to determine a new approach in potential of bio-additives blends operating with bio-petrol on performance and emissions of spark ignition engine. It is shown that the variant in bio-additives blending ratio and engine operational condition are reduced engine-out emissions and increased efficiency. It seems that the bio-additives can increase the maximum cylinder combustion pressure, improve exhaust emissions and largely reduce the friction coefficient. The review concludes that the additives usage in bio-petrol is inseparable for the better engine performance and emission control and further research is needed to develop bio-petrol specific additives.