**1. Introduction**

Fossil fuel has been the primary source of fuel ever since it was discovered and comes in the form of coal, petroleum and natural gas. Discovery of fossil fuel dates back to prehistoric time where caveman discovered how to burn coal for heat source. Coal which is also part of fossil fuel and is developed over millions of years can even extend up to 650 million years. With excessive usage of fossil fuel as source of energy, amount of fossil fuel around the world is declining at a rapid rate. With petroleum being the main source of fuel in automotive industry and power generation, this lead to price hike globally with the fastest depletion rate. Experts forecast that complete depletion of petroleum in the world is expected to happen in between 50 to 80 years depending on the consumption.

In advance, the global fuel crisis in the 1970s triggered awareness amongst many coun‐ tries of their vulnerability to oil embargoes and shortages. In addition, the rising world crude oil is another primary concern for developing countries because it increases their import bills. The world is presently confronted with the twin crisis of fossil fuel deple‐ tion and environmental degradation. Fossil fuels have limited supply and the increasing cost of these fuels has led to the search of renewable fuels to ensure energy security and environmental protection. With increased interest in emissions and reduction of fossil fuels, considerable attention was focused on the development of alternative resources, in particularly biodiesel fuels.

Even more, the effect of global warming is largely felt due to the greenhouse gas emis‐ sion and power producing plants contribute a major involvement in this aspect. Replac‐

© 2013 Tan et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Tan et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ing fossil fuel with renewable energy is one of the main solution. Biodiesel is a renewable, biodegradable and oxygenous fuel with almost similar physical and chemical characteris‐ tic to diesel [1]. Biodiesel are ethylic or methyl esters of acids with long chain derived from vegetable oils and animal fats through a thermochemical process involving the transesteri‐ fication process [2]. In addition, biodiesel being an oxygenated fuel whereby it is environ‐ mentally cleaner than diesel with respect to unburnt hydrocarbon (UHC) and particulate matter (PM) emissions [3]. The success of biodiesel is proven as can be seen in its use as a secondary fuel for vehicle in Europe and followed by other developed countries. The reason for using biodiesel, is that it can increase engine performance and produces low emission compared with conventional diesel fuel [2,5,6,17]. Biodiesel can be obtained from various sources such as palm oil [7], rapessed oil [14-15], soybean oil [8,14-15], vegetable oil [9-10], waste cooking oil [11-12], oleaginous microorganisms [13] and sunflower seed oil [14-15]. An important effect that has to take into consideration is the fuel spray atomizer where‐ by it is the contributing factor that will affect the efficiency and performance of power generation. Spray tip penetration and mean droplet size of which are the atomization characteristics of biodiesel fuel play an important role in the emission characteristics and the engine performance [26]. Biodiesel is mostly applied in transportation like petroleum diesel. Biodiesel blended fuel can be used as fuels for diesel engines without any modifica‐ tion. Moreover, pure biodiesel can be used as well but with some minor modification. Biodiesel gives better lubrication compared to diesel fuel [27-28]. Biodiesel also provides advantages on performance, engine wear, value for money and availability.

spray cone angle, spray width and Sauter Mean Diamater (SMD). Generally, biodiesel has larger spray tip penetration and Sauter Mean Diameter while smaller spray cone angle and spray width compared to diesel. Five sample of fuels will be tested which are B20, B50, B80, B100 and D100. The alphabet B represents biodiesel and the number that follows represents the percentage of the fuel that is made up of biodiesel. For example, B80 simply means biodiesel blend that is made up of 80 % biodiesel and 20 % diesel. Research conducted on biodiesel shows that using biodiesel rather than conventional diesel reduces carbon dioxide pollutants into the environment. Using full 100 % biodiesel (B100) eliminates all sulphur emissions, removes carbon monoxide pollutant and reduces hydrocarbon pollu‐ tant by 75 % to 90 % compared to conventional diesel. This means greenhouse gasses can be significantly reduced if B100 is used because this fuel has no emissions of carbon dioxide [32]. Palm oil will be derived through transesterification process to produce biodiesel and palm oil is easily obtained in Malaysia. Moreover, the price of palm oil will be much cheaper compared with the other resources. Palm oil quality is cleaner and good compared with other fuel. In short, biodiesel will be the most suitable fuel replacement for power genera‐ tion and have more advantage environmental wise. Biodiesel can be used with the existing gas turbine power generation and only a little or no modification has to be made. It is based on the existing concept and idea in diesel engine that had been applied. Further analysis and consideration have to be taken in future to ensure that biodiesel can operate

Biodiesel for Gas Turbine Application — An Atomization Characteristics Study

http://dx.doi.org/10.5772/54154

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The production of biodiesel was completed by conducting transesterification of Waste Cooking Oil (WCO). Relevant method was selected in this project based on its economic factors to produce different biodiesel blended fuels. Biodiesel and diesel blends of B100, B80, B50 and B20 and D100 were obtained through conducting tests that meet the require‐ ments of ASTM D6751, Specification for Biodiesel Fuel Blend Stock for Distillate and ASTM D2880 Standard Specification for Gas Turbine Fuel Oil. This is to ensure that the pro‐ duced biodiesel blended fuels meet the minimum fuel properties standards. Table 1 shows the main fuel properties that were studied with respect to its effects on atomization. Transesterification is the simplest way whereby it uses alcohol (e.g. methanol or ethanol) in the presence of a catalyst such as sodium hydroxide or potassium hydroxide, to chemically break the molecule of the raw material into methyl or ethyl esters of the renewable oil with glycerol as by-product. The chemical reaction of transesterification is ethyl esters of fatty acids plus glycerol equal to triglyceride (animals and plants fats and oil). The triglyceride will have chemical reaction with alcohol that usually is methanol or

ethanol with the presence of a catalyst to produce ethyl ester and crude glycerol.

in the gas turbine without any problem

**2. Research methodology**

**2.1. Fuel properties**

Despite the significant advance arising from definition of the regulatory milestone, there are still many issues relating to the production and use of biodiesel that need to be debated. Among the issues, the ones that stand out are those of a technical order, such as how the biodiesel specifications and its consequences for the performance, emissions and durabili‐ ty of the engine and its system. Therefore, further research on ideal atomization character‐ istics of biodiesel fuels should be carried on for progressive development of this potential source in combustion engineering. Various biodiesel blended fuel derived from waste cooking oil (WCO) are produced through the method of transesterification. ASTM stand‐ ards are used to identify and verify physical and chemical properties such as viscosity, density, flash point and cetane number of the biodiesel produced. Meanwhile, a fuel atomizer designed act as a device that convert the working fuel flow into a finely dis‐ persed flow of fuel droplets in the form of a spray. Fuel spray testing will determine atomization characteristics such as Sauter Mean Diameter (SMD), spray angle, spray width, spray length and spray tip penetration for different types of fuel under certain atomiza‐ tion conditions. Thereafter, a computer simulation using CFD Fluent software is used to compare the experimental results to ascertain the appropriate biodiesel blend to be applied in the microturbine and gas turbine combustion system.

This project is to study the possible application of diesel and biodiesel blends in gas turbine and microturbine application. Research of this project involves testing several composi‐ tions of diesel and biodiesel blends. The produced diesel and biodiesel blends will be tested to understand the behavior and atomization characteristics such as spray tip penetration, spray cone angle, spray width and Sauter Mean Diamater (SMD). Generally, biodiesel has larger spray tip penetration and Sauter Mean Diameter while smaller spray cone angle and spray width compared to diesel. Five sample of fuels will be tested which are B20, B50, B80, B100 and D100. The alphabet B represents biodiesel and the number that follows represents the percentage of the fuel that is made up of biodiesel. For example, B80 simply means biodiesel blend that is made up of 80 % biodiesel and 20 % diesel. Research conducted on biodiesel shows that using biodiesel rather than conventional diesel reduces carbon dioxide pollutants into the environment. Using full 100 % biodiesel (B100) eliminates all sulphur emissions, removes carbon monoxide pollutant and reduces hydrocarbon pollu‐ tant by 75 % to 90 % compared to conventional diesel. This means greenhouse gasses can be significantly reduced if B100 is used because this fuel has no emissions of carbon dioxide [32]. Palm oil will be derived through transesterification process to produce biodiesel and palm oil is easily obtained in Malaysia. Moreover, the price of palm oil will be much cheaper compared with the other resources. Palm oil quality is cleaner and good compared with other fuel. In short, biodiesel will be the most suitable fuel replacement for power genera‐ tion and have more advantage environmental wise. Biodiesel can be used with the existing gas turbine power generation and only a little or no modification has to be made. It is based on the existing concept and idea in diesel engine that had been applied. Further analysis and consideration have to be taken in future to ensure that biodiesel can operate in the gas turbine without any problem
