Fuel properties, performance and emission characterization of waste cooking oil (WCO) in a variable compression ratio (VCR) diesel engine

European Mechanical Science 2017, Vol. 1(2): 56-62 Research Paper EUROPEAN MECHANICAL SCIENCE Fuel properties, performance and emission characterization of waste cooking oil (WCO) in a variable compression ratio (VCR) diesel engine§ Şafak Yıldızhan1*, Erinç Uludamar2, Ahmet Çalık3, Gonca Dede4, Mustafa Özcanlı5 Department of Automotive Engineering, Çukurova University, Turkey Department of Automotive Engineering, Adana Science and Technology University, Turkey 4 Department of Automotive Engineering, Amasya University, Turkey 1,5 2,3 Abstract The current study investigates the fuel properties, performance and emission characteristics in a variable compression ratio (VCR) diesel of the biodiesel produced from the waste cooking oil (WCO). The WCO samples were collected from the university and converted to biodiesel fuel with a two-step transesterification reaction. The fuel property tests showed that the properties of the WCO biodiesel were within the biodiesel standards. Diesel, WCO biodiesel and diesel-WCO biodiesel blend (B20) was used as fuel in a VCR engine. The performance and emission characteristics of the engine were measured at two different compression ratios (14:1 and 16:1) under partial load conditions. The experimental results showed that WCO biodiesel slightly decreased the brake thermal efficiency and thus increased specific fuel consumption. Biodiesel usage improved CO emissions up to 21,75% compared to diesel fuel. But, biodiesel usage increased CO2 and NOx emission due to higher combustion temperature and extra oxygen content of the biodiesel. Keywords: Compression ratio, Alcohol, Biodiesel, Performance, Emission 1. INTRODUCTION Fossil fuels which are the main energy source for transportation of people and goods are depleting as it is known widely and the price of the fuel is increasing due to demand and supply facts [1]. Also, enviromental effects of the fossil fuels threaten the human heallt and nature of all world. The exhaust emissions of the internal combustion engines are formed by the combustion fuels and these gases include toxic pollutants such as carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOx), unburned hydrocarbons (UHC), sulphur dioxide (SO2), and etc. These toxic gases are dangereosly harmful for human healt and the nature [2]. The known facts force researchers to look for alternative energy sources for internal combustion engines. Biodiesel, which can be derived from vegetable oils and animal fats has a potential of being a substitute since biodiesel fuels are less toxic and renewable [3]. Many raw materials have been studied by many researchers [1, 4-11]. Also, biodiesels are not significantly worse than fossil fuels in the means of engine performance. Biodiesels are mostly derived with transesterification reaction or thermal cracking methods. The main raw material of biodiesel are mostly non-edible vegetable oils, animal fats and waste oils. The necessity of large agricultural areas and the high effort for production of vegetable oils are one of the most important drawbacks of biodiesel usage. But, tonnes of oils are used all over the world for different purposes. Especially, the food industry produce a high amount of waste frying oil. The waste of food industries and even the waste oils used in the houses are hazardous for enviroment unless the wastes are managed properly. The trend of renewable processes have been started to spread recently. Even the local city corporations are aware of the huge amount of oil wastes and have some efforts on this particular subject. Recycle of waste materials is a popular research subject. Reproduction processes from the waste material are eco-friendly and economically useful since the raw materials are already used up and the unit reproduction cost can be pulled down of the original production cost in some cases. In literature, there are many investigations on the production, performance, emission and combustion characteristics of biodiesels [12-19]. Hwang et al., (2016) published an article that investigates effects of biodiesel usage produced from *Corresponding authour Email: (Ş. Yıldızhan) § This paper was presented in the IMSEC-2016 waste cooking oil on a compression ignition engine. The authors reported that waste cooking oil (WCO) biodiesel usage decreased the CO, hydrocarbon (HC) and smoke emissions, and also WCO biodiesel caused a slight decrement of in-cylinder pressure [20]. Man et al., (2016) reported a study that studies the effects of WCO-diesel blends on emission characteristics of a diesel engines. The study revealed that, WCO-diesel blend usage caused to increase of NOx emissions. But, CO, HC and particulate matter emisssion were decreased by WCO-diesel blends usage [21]. Piker et al., (2016) studied the on the biodiesel production from the waste oil bu using egg shells as catalyst. The authors reported that fatty acid methyl ester yield of 97 wt.% was obtained after 11 h at ambient temperature and pressure with egg shells [22]. In this study, fuel properties of waste cooking oil biodiesel and the effects of the biodiesel produced from waste frying oil that collected from the university on the performance and emission characteristics of a variable compression ratio (VCR) diesel engine were investigated. 2. METHODOLOGY 2.1 Experimental Fuels The experimental study was conducted in Petroleum Research and Automotive Engineering Laboratories of the Department of Automotive Engineering at Çukurova University. Waste cooking oil (WCO) samples were used as raw material for biodiesel production. WCO biodiesel was produced with two-step transesterification reaction. First, the collected oil samples were filtered prior to reaction in order to clean the contaminants. The free fatty acid (FFA) value of the cleaned oil was measured with the standard titration method. The FFA of the WCO was measured as 1,93 wt. %. Transesterification reaction was performed twice the FFA of WCO is high. The first reaction was performed at 65oC for 60 minutes by stirring. Methanol 20 wt. % and 0,5 wt. % sodium hydroxide was used as reactant and catalyst, respectively. The methoxide was obtained before transesterification reaction by mixing methanol and sodium hydroxide. The second transesterification reaction was performed with methanol 10 wt. % and 0,25 wt. % sodium hydroxide under same conditions. After the reaction period, the mixture were batched in a separating funnel for 8 hours and at the end of the batching period the glycerine was separated from the mixture. After the separating the glycerine from the mixture, crude WCO biodiesel samples were obtained. Then, the crude biodiesel was washed with warm water and dried at 105 oC for one hour. Finally, in order to purify and to refine biodiesel the crude biodiesel was filtered. The biodiesel production flow diagram was shown in Figure 1. Figure 1: Biodiesel production flow diagram In the study, low sulphur diesel fuel (conventional d (...truncated)