Kulachate Pianthong

Combustion Efficiency and Performance of RSO Biodiesel as Alternative Fuel in a Single Cylinder CI Engine

In this study, the combustion efficiency and performance of an engine using biodiesel produced from rubber seed oil (RSO) was compared with petroleum diesel. The tests were performed at full load over a range of engine speeds in a single cylinder, direct injection diesel engine. The experimental results show that the RSO biodiesel resulted in better combustion than with the petroleum diesel at low to medium engine speeds (1300–1900 rpm). In this range, the combustion efficiency and the brake fuel conversion efficiency of the RSO biodiesel were found to be 1.03% and 7.33% higher respectively than those of petroleum diesel. In addition, a slightly lower brake specific CO2 emission level was achieved, this being because of the higher H/C ratio of the RSO biodiesel. A major improvement in the brake specific CO emission of the RSO biodiesel was found, these being 55% lower than those of the petroleum diesel. However, the brake specific NOx emission was 39.5% higher. Both the brake torque and brake power of the RSO biodiesel were 4.91% lower than those of the petroleum diesel while an increase of around 6.84% fuel consumption was required at the same power output all these being due to its lower heating value. Above 1900 rpm in these tests, the combustion efficiency trend reversed with the RSO biodiesel giving a lower value than the petroleum diesel. In this higher speed range, the performance (i.e. brake fuel conversion efficiency, brake power, and brake torque) fell below that of the petroleum diesel with the brake specific fuel consumptions and the brake specific CO emissions being higher.

Experimental Study of Ignition over Impact-Driven Supersonic Liquid Fuel Jet

This study experimentally investigates the mechanism of the ignition of the supersonic liquid fuel jet by the visualization. N-Hexadecane having the cetane number of 100 was used as a liquid for the jet in order to enhance the ignition potential of the liquid fuel jet. Moreover, the heat column and the high intensity CO2 laser were applied to initiate the ignition. The ignition over the liquid fuel jet was visualized by a high-speed digital video camera with a shadowgraph system. From the shadowgraph images, the autoignition or ignition of the supersonic liquid fuel jet, at the velocity of 1,186 m/s which is a Mach number relative to the air of 3.41, did not take place. The ignition still did not occur, even though the heat column or the high intensity CO2 laser was alone applied. The attempt to initiate the ignition over the liquid fuel jet was achieved by applying both the heat column and the high intensity CO2 laser. Observing the signs of luminous spots or flames in the shadowgraph would readily indicate the presence of ignitions. The mechanism of the ignition and combustion over the liquid fuel jet was clearly clarified. Moreover, it was found that the ignition over the supersonic liquid fuel jet in this study was rather the force ignition than being the auto-ignition induced by shock wave heating.

Effect of Stand‐Off Distance on Impact Pressure of High Speed Water Jets

High speed liquid jets may be applied to jet cutting, drilling and cleaning. Recently, in the automotive industries, the spray injection pressure becomes higher and higher to enhance the fuel mixing for the improved combustion efficiency. However, the ultra high injection pressure may cause the damage to the nozzle and also the combustion chamber. In the medical application, the high speed liquid injection might be applied for the drug delivery through the skin where the needle is not required anymore. From the above mentioned application, the investigation on the impact pressure of the high speed liquid jet relative to the stand‐off distant is significant. The high speed liquid jets are generated by the projectile impact driven method. The high speed projectile is launched by the horizontal single stage powder gun. The experimental study focuses on the stand‐off between 1.5 cm to 6.0 cm, while the nozzle contains approximately 1.5cm3 of water in its cavity. The nozzle conical angles are 30° and 60° with ...

Effects of Different Liquid Properties on the Characteristics of Impact-Generated High-Speed Liquid Jets

This paper describes the study of high-speed liquid jets injected in air from an orifice. The main focus is to study the effect of different liquid properties on the characteristics of the high-speed liquid jets injected in ambient air. The high-speed liquid jets are generated by the impact of a projectile, which known as impact acceleration method, launched in a horizontal single-stage power gun (HSSPG). The conical nozzle of 30° angle with the orifice diameter of 0.7 mm was used to generate the jets. The characteristics of high-speed jets were visualized by the high-speed digital video camera with shadowgraph optical arrangement. From the shadowgraph images, the jet formation, atomization, vaporization and shock waves were obviously observed. The maximum averaged velocity of water, alcohol, n-hexane, chloroform and glycerin jets is estimated to be 1,669.03 m/s, 1,548.59 m/s, 1,420.44 m/s, 1,204.46 m/s and 1,496.97 m/s, respectively. That effect on the maximum penetration distance of the water jet is longer than that of all jets. Surface tension and latent heat are the significant physical property for jet formation, while density, kinematics viscosity and heat capacity are not.

Effect on the Use of Ultrasonic Cavitation for Biodiesel Production from Crued Jatropha Curcas L. Seed Oil with a High Content of Free Fatty Acid

A typical way to produce biodiesel is the transesterification of plant oils. This is commonly carried out by treating the pre-extracted oil with an appropriate alcohol in the presence of an acidic or alkaline catalyst over one or two hours in a batch reactor.Because oils and methanol are not completely miscible. It has been widely demonstrated that low-frequency ultrasonic irradiation is an effective tool for emulsifying immiscible liquids. The objective of this research is to investigate the optimum conditions for biodiesel production from crude Jatropha curcas oil with short chain alcohols by ultrasonic cavitation (at 40 kHz frequency and 400 Watt) assisted, using two step catalyst method. Usually, the crude Jatropha curcas oil has very high free fatty acid which obstructs the transesterification reaction. As a result it provides low yield of biodiesel production. In the first step, the reaction was carried out in the presence of sulfuric acid as an acid catalyst. The product was then further transesterified with potassium hydroxide in the second step. The effects of different operating parameters such as molar ratio of reactants, catalyst quantity, and operating temperature, have been studied with the aim of process optimization. It has been observed that the mass transfer and kinetic rate enhancements were due to the increase in interfacial area and activity of the microscopic and macroscopic bubbles formed. For example, the product yield levels of more than 90% have been observed with the use of ultrasonic cavitation in about 60 minutes under room temperature operating conditions.

Visualization of Supersonic Non-Newtonian Liquid Jets

This paper describes the characteristics of supersonic non-Newtonian liquid jets injected in ambient air. The main focus is to visualize three types of time-independent non-Newtonian liquid jet and to describe their behaviors. Moreover, comparisons between their dynamic behaviors with Newtonian liquid jet are reported. The supersonic liquid jets are generated by impact driven method in a horizontal single-stage power gun. Jets have been visualized by the high speed digital video camera and shadowgraph method. Effects of different liquid types on the jet penetration distance, average jet velocity and other characteristics have been examined. From shadowgraph images, the unique dynamic behaviors of each non-Newtonian liquid jets are observed and found obviously different from that of the Newtonian liquid jet. The maximum average jet velocity of 1,802.18 m/s (Mach no. 5.30) has been obtained. The jet penetration distance and average velocity are significantly varied when the liquid types are different.

Effect of Stand-Off Distance on Impact Pressure of High-Speed Water Jet Injected in Water

This study is to measure the impact pressure of high-speed water jet injected in water at the stand-off distance from the nozzle exit. The high-speed water jets are generated by the impact of a projectile, which known as impact acceleration method, launched by Horizontal Single Stage Power Gun. The maximum averaged jet velocity of about 374.24 m/s in water was generated in this experiment. The impact pressure of high-speed water jet in water at the stand-off distance 15, 20, 30 and 40 mm from the nozzle exit was measured by the PVDF pressure sensor. Moreover, the impact phenomena of the jet were visualized by a high-speed video camera with shadowgraph optical arrangement. From the pressure sensor, two peak over-pressures are always observed in this experiment. From visualization, it was found that the two peak over-pressures of 24 GPa and 35 GPa at x = 15 mm were generated by the jet and the bubble impact, respectively. The peak over-pressure decreases exponentially as the stand-off distance between the PVDF pressure sensor to the nozzle exit increases. Moreover, the jet and the bubble impact on the PVDF pressure sensor, shock waves, and bubble deformation were obviously observed in this study.

Injection pressure and velocity of impact-driven liquid jets

Purpose – The purpose of this paper is to describe a procedure to simulate impact-driven liquid jets by computational fluid dynamics (CFD). The proposed CFD model is used to investigate nozzle flow behavior under ultra-high injection pressure and jet velocities generated by the impact driven method (IDM). Design/methodology/approach – A CFD technique was employed to simulate the jet generation process. The injection process was simulated by using a two-phase flow mixture model, while the projectile motion was modeled the moving mesh technique. CFD results were compared with experimental results from jets generated by the IDM. Findings – The paper provides a procedure to simulate impact-driven liquid jets by CFD. The validation shows reasonable agreement to previous experimental results. The pressure fluctuations inside the nozzle cavity strongly affect the liquid jet formation. The average jet velocity and the injection pressure depends mainly on the impact momentum and the volume of liquid in the nozzle,...

Effects of precursory stress waves along a wall of a container of liquid on intermittent jet formation

This paper describes results of pressure measurements and double exposure holographic interferometric visualization of waves propagating in a conically shaped container of liquid during high-speed liquid jets generation by impact acceleration method using a vertical two-stage light gas gun. To verify the contribution of longitudinal and transversal waves created in metal containers, we used a 10.6 mm x 10.6 mm container of water with thick acrylic observation windows and quantitatively visualized waves by using double exposure holographic interferometry. We found the presence of stress waves released in water, whose effect was cancelled with wave interaction in the container.

Attenuation and penetration of pulsed supersonic liquid jets—An experimental study

Pulsed supersonic liquid (water and diesel fuel) jets in the range of 1500 m/s to 1800 m/s have been produced and examined. A two stage light gas gun was used as a launcher to obtain the pulsed impact (velocity of 700m/s). In this paper, experimental results on the attenuation and the penetration distance of the liquid jets is presented. It was found that the attenuation is relatively high in the first 300 μs of the jet flight. The penetration distance is around 300–500 mm, this depending on the initial velocity, the nozzle geometry and the properties of liquid. The experimental results agree well with the estimation using conventional diesel spray formula. The shadowgraph image shows bow shock wave structures with multiple pulses which tend to enhance atomization and combustion. However, further examination of their atomization related to the jet attenuation and penetration distance is needed.