Contribution to experimental research of alternate fuel fumigation in single cylinder research diesel engine

The advanced engineering scientific paper encompass the problem of supplying fuel in engine’s combustion chamber in order to outline the influence of operating regime and fumigation method upon injection and fuel consumption. It develops a theoretical and experimental approach of the system components from Lombardini compression ignited engine test bench in relation with consumption and fumigation parameters. There was monitored engine speed, dynamic behaviour at some distinct operating loads. The opportunity for experimental research of the fumigation method in compression ignited engine resides in the state of the art technology accessible today for alternate fuel supply inside engine through this process. The results are analysed and discussed in detail. The fuel fumigation method is applicable to the presented engine and leads to some positive behaviour in operation.


Introduction
This paper develops a theoretical and applied research protocol which is a part of the complex phenomenological mapping of a Single Cylinder Research Diesel Engine (SCRDE), which has as result even an innovation patent with the fumigation features.
In the present age, when the expectations concerning the fuel supply systems for internal combustion engines are higher and strictly evaluated and the operation is electronically controlled it is both necessary and important to reconsider and adjust the existing knowledge and methods for air-fuel mixture formation in order to improve engine performances at economy and pollution levels.
The research paper shows a set of operating theories from the bottom of this system, a study of the fuel supply system from the internal combustion engine and a set of results from the experimental research concerning the dynamic behaviour in various operating conditions during the laboratory tests made with a hydraulic brake.

Review of the scientific literature
The fumigation problem is being studied and treated with serious concern by the scientific and engineering community for a time now. Bio-fuels and fumigation are two major directions that are closely considered by a specific part of the scientific research literature [1][2][3].
Bio-fuel has come under consideration due to the effect of fossil oil crisis. Bio-fuels are acting as a renewable replacement of petroleum fuels due to some environmental and economic benefits. Bio-fuel can be produced from different kinds of raw materials. Researchers have seen that absolute utilization of bio-fuel is not appreciable as it will affect the food chain but the blend of bio-fuel with conventional fuel could precisely reduce its use and become beneficial to greenhouse effect. It has been inferred that in the hot and cold environment bio-fuel is not fully convenient to replace fossil fuel. In the controlled environment with modified combustion equipment, biodiesel can be used as an alternate fuel 5.
Intensive investigation on different alcohols, mainly ethanol and methanol and combination of them with diesel fuel is used for reducing the emissions of nitric oxides (NOx) and PM [1]. The diesel fuel and alcohols are generally employed together either in the blended mode or even in the fumigation mode [5][6][7][8][9], although there are less investigation being conducted on different approaches like dual fuel injection system. In comparison to the blended mode, the fumigation method is definitely seems more flexible despite extra fuel injection system is required. First it allows the quantity of alcohol to vary at the time of injection to meet the actual demand. Second, since the alcohol is not premixed while using as diesel fuel, an emulsion additive is added to ensure proper mixing of the alcohol [4][5][6][7][8][9][10][11].

Our activities related to the subject
The research team has a constant preoccupation for developing studies and research programs for optimizing internal combustion engines and for smoothing the transition toward a cleaner environment and less pollutant automotive field.
Last year, the effects of an experimental bioethanol fumigation application using an experimental ultrasound device on performance and emissions of a single cylinder Diesel engine have been experimentally investigated. Engine performance and pollutant emissions variations were considered for three different types of fuels (biodiesel, biodiesel-bioethanol blend, and biodieselfumigated bioethanol). Reductions in brake specific fuel consumption and NOx pollutant emissions are correlated with the use of ultrasonic fumigation of bioethanol fuel, comparative to use of biodiesel-bioethanol blend [5,6].
Considering the fuel consumption as Diesel engine's main performance parameter, the proposed bioethanol's fumigation method, offers the possibility to use more efficient renewable biofuels (bioethanol), with immediate effects on environmental protection [5][6][7].

Continuation of the study at the present moment
In the present stage there is a patent proposal in progress on a method for multi-fuel supply in the internal combustion engines with aerosols produced through ultrasonic waves applied to biofuels based on alcohols and a research concerning fumigation in the air-fuel supply system from compression ignited engine. Also the phases of development for the internal research project at Technical University from Cluj-Napoca are treated with full responsibility in order to achieve the proposed objectives.

Mathematical models
To study all the engine's parameters concerning the consumption, optimal operation, output power, torque and break specific consumption it is necessary to highlight the mathematical models which are at the basis of each calculation after experimental measurements.
Hourly fuel consumption is determined with the mathematical relation 8:

Materials and method
In order to develop the research work and to measure all the envisaged parameters the engineering staff and technicians prepared a test bench with an internal combustion engine from tractor company Lombardini, that operates on the fundamental cycle of four stroke compression ignition, with a single cylinder and direct injection, being air cooled. Beside the single cylinder research engine there were also used some devices to measure the temperature, the engine speed, the output torque and power. Figure 1 represents the schematic principle of ultrasonic fumigation process and technology [6]. 1-ultrasonic emitter; 2-fan, 3-air; 4-bioethanol; 5-intake pipe; 6-intake pipe air stream; 7-fumigated bioethanol; 8-fuel injector; 9-exhaust pipe.
Method applied in this research uses the causal relation to highlight the influence of the innovative procedure of fumigation when supply the fuel to engine intake, using also a special procedure of sonication.
Also the methodology for determining the operating and economic parameters follows a protocol similar to the one presented in figure 2.

Idea of ultrasonic fumigation process and technology
Theoretical study of the field and documentation Validation of the theoretical principles in laboratory Patent development for the ultrasonic fumigation process Figure 3 presents the engine test bed and the equipment linked to the bench in order to measure and determine the fuel consumption parameters.
Monitoring the parameters and tracing the engine operation diagrams during the tests were realized with a specialized data acquisition system, which is made of auxiliary devices and also optical units for electronic data storage. Single cylinder engine is mounted on a test bed mechanically coupled with a hydraulic brake and electronically linked with data acquisition/storage system. Also the engine exhaust pipe is connected with the gas sensor of the pollutant analyzer.

Torque and pressure measurement
In order to obtain reliable torque measurements (Table 1) the engine's crankshaft was break down by a hydraulic brake and the indicated values were recorded from a corresponding display panel (Fig. 4). The level of engine speed ( Table 2) was measured with sensors put on the engine and upon hydraulic brake. In relation with the engine speeds and combustion chamber gas pressure data, the processing system has represented the indicated diagram (pressure vs. volume), thus being possible a series of complex analyzes concerning energetic performances during the operation in different fuel supply (injection, fumigation etc.) conditions.

Engine load results displayed on chart
The practical determinations were presented on graphic charts in order to facilitate their observation, to describe their trends and to study engine's behavior (Fig. 5). The engine's load coefficient presents high levels when torque output riches the upper scale indicated by the manufacturer. At low torques the engine loads are similar, but at the maximum points the load differs between the biodiesel and diesel fuel delivered to the combustion chamber.

Fuel consumption determination
Engine's (hourly and specific) fuel consumptions determined on test bench in laboratory conditions are represented in comparative graphics ( Fig. 6 and Fig. 7). It was observed that the fuel consumption in both case of fuel delivery methods are close related to the engine's torque output.

Environment impact evaluation
In research developing process a particular phase was reserved to the environmental impact evaluation. There were recorded all the relevant data related to the smoke opacity (Fig. 8) and nitric oxides (Fig. 9).

Conclusion
Engine's (hourly and specific) fuel consumptions determined on test bench in laboratory conditions are represented in comparative graphics ( Fig. 6 and Fig. 7).