VOL. 11, NO. 18, SEPTEMBER 2016 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2016 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 11183 RAPESEED OIL SPRAY DEVELOPMENT OF DIESEL IDI SPRAY NOZZLE UNDER AIR MOVEMENT INFLUENCE Azwan Sapit, Akmal Nizam Mohammed, Mohd. Azahari Razali, Mohd Faisal Bin Hushim, Amir Khalid and Bukhari Manshoor Automotive Research Group, Faculty of Mechanical and Manufacturing Engineering, UniversitiTun Hussein Onn Malaysia, Parit Raja, BatuPahat, Johor, Malaysia E-Mail: azwans@uthm.edu.my ABSTRACT Rapeseed oil (RO) spray has very slow atomization due to its high viscosity nature. Although high injection pressure, high ambient temperature and combination of nozzle can promote faster atomization of rapeseed oil spray, another factor that was not discussed is the effect air movement that could positively influence RO spray development. To study the effect of air movement, in particular to generate the swirl (air movement inside the chamber), a swirler was used. Images were captured using a nano-spark shadowgraph photography technique and also high speed video imaging. Macrostructures of diesel sprays such as spray tip penetration length, spray shape, spraycone angle were obtained. Microstructures, such as droplet distribution and size were also studied. Result shows that IDI nozzle rapeseed oil spray has a narrow spray cone angle. The average droplet size is around 20~25µm. The large size of rapeseed oil droplet require assistant to improve atomization and results shows rapid air movement in chamber successfully improve atomization. Keywords: diesel engine, alternative fuel, rapeseed oil, sustainable energy, fuel injection, spray. INTRODUCTION In has been proven from the results of previous study that RO spray has very slow atomization due to its high viscosity nature [1-3]. Although high injection pressure, high ambient temperature and combination of nozzle geometry with piston cavity design and suitable injection strategy can promote faster atomization of RO spray[4-9], another factor that was not discussed is the effect air movement that could positively influence RO spray development. It should also be stated that the diesel spray injector used in previous experiments [8,9]is for the use of DI diesel engine, which generally use the concept offast fuel – slow air mixing. This is due to the fact that DI diesel engine has to force the fuel to penetrate highly compressed air, the fuel need to be of high velocity. In contrast, as the fuel is injected directly to the spray chamber, air movement is relatively slow and quite limited. On the other hand, IDI diesel engine uses a different air mixing strategy, which is slow fuel – fast air mixing. IDI diesel engine usually designed to have a prechamber (small space to initiate air fuel mixing) that the spray is injected into. Air movement inside the combustion chamber is amplified as it move through the prechamber where it will mix with the fuel before making it way to the main combustion chamber. This process made effective fuel air mixing possible. The fast movement of air mitigates the need of high velocity spray jet, which make IDI diesel engine not requiring high injection pressure fuel delivery system. This study focuses on the use of RO in IDI diesel engine. As the usage of alternative fuel (in this case, RO) is not limited to one type of engine only (DI and IDI diesel engine)[10-11], the study of any viable condition that could help to improve the spray atomization is commendable. In addition, the usage of RO in IDI diesel engine was strongly suggested to be actually more suitable then DI especially when considering the possibility of injector choking which can be a major problem when using RO to DI diesel engine. As IDI diesel engine spray use the pintle-type nozzle, this risk is largely reduced. Experiment setup Figure-1 shows the experimental setup of shadowgraph photography. The experimental system is the same as previous work [7]. It is composed of spray chamber, rapid compression machine (RCM), fuel injection device and optical system. A rapid compression machine was used to create diesel atmosphere in the spray chamber. The spray chamber has two quartz windows in diameter of 60mmfor the access of nano-spark light to a still camera. The spray chamber was filled with inert gas mixture of nitrogen and argon to prevent spray ignition. When ambient temperature reaches designated temperature after termination of rapid compression, fuel was injected into the spray chamber and spray behavior was taken by the optical system. All the images taken by films were scanned and changed to digital pictures. Then using in house algorithm system developed by Yatsufusa [8], the image is analyze and spray fuel droplet can be verified. To study the effect of air movement, in particular to generate the swirl (air movement inside the chamber), a swirler was used. This swirler is fixed inside the chamber as shown in Figure-2, just after the stop ring. It functions by carefully guiding the inert gas that is propelled by the rapid compression machine to move into the chamber in an angle (α)which will produce fast air movement (swirl). At the same time, as inert gas is being compressed inside the chamber, high ambient temperature also is generated.