The energy accessibility is the first challenge of this century. More forms of resources are used to produce energy. However, the environment pollution due to the usage of fossil fuels is the main problem that must be solved for these decades. Many scientists propose a diversification of the energy production by using raw vegetable materials that are renewable and sustainable [1] [2]. Among them, biodiesel can be produced and used in the compression ignition engine in replacement of traditional diesel. We note that these fuels have similar physicochemical properties with the fossil fuels [3] [4].

Compared to the spark engine, the diesel engine produces more pollutants during the combustion of its fuel even though its high compression ratio leads to a good thermal yield [5]. Carbon dioxide (CO₂), carbon monoxide (CO), Nitrogen oxides (NO_x), Hydrocarbons (HC) and fine material particles (PM) are the important pollutants resulting from diesel engines [6] [7] [8] [9].

To propose an alternative solution, the transesterification reaction can be used to produce biodiesel from vegetable or animal oils. Many authors studied the performances of the internal combustion engine fueled with biodiesel and described its combustion characteristics [10] [11]. Biodiesel presents more advantages than the fossil diesel. It is a renewable energy resource, less toxic, biodegradable and products less pollutants during its combustion [12]. Luka et al. noticed the introduction of biodiesel, even in small amounts, leads to the reduction of CO and NO_x at different speeds of a diesel engine fueled with neat biodiesel made from rapeseed oil and their blends (B25, B50 and B75). The presence of oxygen in the biodiesel chemical structure was found as the main contribution of this reduction [13]. Indeed, the biodiesel chemical structure has an effect on the exhaust emissions. In addition, the combination of the chain length (number of carbon) and the unsaturation degree of fatty acid methyl esters has an important role in the NO_x emissions [14]. Even, the emissions of CO, total HC, volatile organic fraction and soot increased with the chain length, as related by the same author. While using pentanol blends to diesel and biodiesel, at different ratios, in a single-cylinder direct injection diesel engine; the soot formation increased with the pentanol addition. Therefore, the NO_x emissions were reduced. The same behavior was detected for the exhaust containing oxygen atom such as CO and CO₂ [15].

Furthermore, biodiesel presents disadvantages, for having a weak energy capacity. It is noticed that this fuel is less favorable to cold flow due to its high viscosity that contributes to the volatility properties during its combustion [5].

To improve these disadvantages, several researches were carried out with various types of biodiesels [16] [17]. The main solution proposed by many authors is a blend of this product with the traditional fossil fuels in many proportions. So, the abbreviations of B5, B10, …, B100 are used to show the amount of biodiesel in the mixtures [7].

Compared to biodiesel, the combustion characteristic of ethanol-biodiesel blends (BE5) in a 4-cylinder direct-injection diesel engine presented a higher brake thermal efficiency (BTE) and leaded to the reduction of NO_x and particulate emissions [7]. The author concluded that by increasing the proportion of ethanol in the blends, the HC and CO emissions could increase.

The specific fuel consumption and the brake thermal efficiency of a low heat rejection diesel engine (Mercedes-Benz/OM364A) were improved by using biodiesel produced from sunflower oil and the determination of the exhaust gas temperature were performed and showed that this parameter was increased before the turbine inlet for the studied fuels [18]. In the same way, the usage of biodiesel in in-line 6 cylinders, intercooled, turbocharged diesel engine at high altitude improved the increase of the brake specific fuel consumption (BSFC) and the volumetric brake specific fuel consumption. According to the previous parameters, the brake thermal efficiency was slightly higher while using diesel than biodiesel [19].

To predict the brake power, torque, specific fuel consumption and exhaust emissions of a 2 cylinders-RD270 Ruggerini diesel engine, running with biodiesel obtained from waste vegetable cooking oil of a restaurant, the neutral network design was used. The results showed that the brake specific fuel consumption of the fuel blends (B10, B20, B30, B40 and B50) compared to diesel (B0) is very similar. However, the increasing fuel blend percentage leaded to a mild increase of the brake specific fuel consumption. The variations of the power and the engine torque per the engine speed were very similar for the all studied fuels [20].

The emissions characteristics of a diesel engine operating on biodiesel and biodiesel blended with ethanol and methanol showed that the increasing of the alcohol amount in the fuel decreased the emissions of NO_x and PM. However, HC and CO emissions could increase and the brake thermal efficiency could slightly reduce by the use of more than 5% of alcohol in the blends [7]. In the same way, a delayed start of combustion and lower combustion duration are observed for biodiesel-methanol blend compared to neat biodiesel fuel in four cylinder in-line turbocharged direct injection diesel engine [21]. The authors showed that the addition of 10% of methanol improved the increasing of the thermal efficiency by 4.2%.

To determine the proportion between biodiesel and diesel for compression ignition engines, the main injection and the atomization properties related to the quality of ignition were measured. The authors noticed that the blends from B2 to B30 present satisfactory properties for their usage in diesel engines. This study was based on the soybean ethylic biodiesel [22].

The effect of biodiesel addition on the diesel engine characteristics showed a slight deviation of the engine torque, power, brake specific consumption, exhaust gas temperature and CO-CO₂ emissions in function of the engine speeds. The biodiesel used was produced from Hazelnut soapstock and waste sunflower oil mixed in equal volume and tested on a 4-cyminders indirect injection diesel engine [23].

It is noticed that the preheating vegetable oils have a good effect on the oils physicochemical properties such as their density and their viscosity and then, on the combustion. This seems to present a benefit on the utilization of vegetable oils as fuels in internal combustion engines (for example in a diesel engine) [24].

This study aims to investigate the performances of a single-cylinder diesel engine using blends of diesel with biodiesels derived from palm oil, castor oil and raphia sese De Wild oil respectively with pure diesel. The measurements of the engine performances for different engine speeds at full load, on the one hand, and at constant speed for the partial loads on the other hand are improved respectively.