Biodiesel fuel properties are evaluated in accordance with EN 14214 standard. Bit diesel engine Testbed fueled with biodiesel engine performance and exhaust emissions were reported with different variations.
What are the key fuel properties which influence both performance and exhaust emissions.
Three fuel properties that affect efficiency and related performance issues and emissions are (1) moisture content, (2) oxygen content, and (3) viscosity (or droplet size). Increasing moisture content decreases efficiency and in-cylinder temperature, which decreases NOx. Efficiency for an actively controlled (O2 sensor equipped engine) increases with increasing oxygen content (because less air is required) but mileage decreases. NOx increases but HC and soot decrease. Increasing viscosity increases droplet size and decreases efficiency and can increase soot and HC.
Long-term performance, such as corrosion, seals, and rings, are affected by Ph, residual inorganics, and other issues.
fuel properties that affect performance and emissions are (a) moisture content, (b) oxygen content, and (3) viscosity (or droplet size) (4) Calorific value of the biodiesel (5) Small Chemical content .
Effects:
a. Increasing moisture content decreases efficiency and in-cylinder temperature, which decreases NOx which are mainly formed at high temperatures.
b. Efficiency for an actively controlled (O2 sensor equipped engine) increases with increasing oxygen content in built oxygen but mileage decreases because of low calorific value.
c. CO2 increases but HC, CO and soot decrease. However Increasing viscosity increases droplet size and decreases efficiency and can increase soot and HC.
d. Long-term performance, such as corrosion, seals, and rings, are affected by Ph, residual inorganics such as residual acid, and other issues.
biodiesel:
calorific value - low torque and power, high fuel consumption,
viscosity and density - bad fuel atomization, obstructed flow,
boiling temperature - bad engine starting,
the molecular oxygen - low smoke emission (and HC, CO, CO2), high NOx.
In general, fuels are characterized by their oxygen content, heating value, cetane number, viscosity, density, cold flow properties such as cloud and pour points, flash point, ash content, sulfur content, carbon residue, lubricity and acid value. These physical and chemical properties of biodiesel depend on the characteristics of feedstock such as carbon chain length, saturation, location and types of double bond (cis or trans) etc. It has been demonstrated with the help of literature review that engine performance and exhaust emissions depend on these physical and chemical properties. Bulk modulus of elasticity and sound velocity determine the injection delay, cetane number influences ignition delay, viscosity, volatility and surface tension affect injection characteristics and oxygen content, heating value etc. affect the combustion characteristics.
Biodiesel due to its inherent characteristics such as high viscosity, low volatility, and unsaturation may contribute to the deposit formation in the combustion chamber after the engine has operated for longer duration of time. Wear of engine is highly influenced by lubricity, acid value as well as oxidative stability.
The exhaust emission n performance is basically reflect from viscosity. High viscosity lead to poor spray atomization. Hence it will perfectly effect the engine.
Viscosity( Atomisation) of fuel is the primary property of bio diesel which influences combustion.
Cetane Number comes second as it determines the Heat rate.
Since Bio fuel is a blend with diesel, the rest gets taken care by diesel.
1. Combustion characteristics is affected CN and Viscosity.
2. The performance parameters is depend mainly on the calorific value
3.The emission parameters (CO- NOx) is depend on oxygen quantity in the bio diesel
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