13-10-2012, 01:22 PM
Ethanol blend fuel
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Introduction
Ethanol as a gasoline bland has helped to reduce on oil import and harmful vehicular emission, and improve rural economy.
Ethanol as a fuel blend has distinct advantages because of its compatile blending with motor gasoline.
Today fuel ethanol accounts for roughly two-third of the world ethyl alcohol production. India is the fourth largest country to produce ethanol.
Ethanol must be explored more seriously as a long term alternative fuel option.
The Brazil Example
Brazil’s National Alcohol programmed was introduce in 1975
Created a market where Brazilian gasoline powered vehicle operated on at least 22% by volume ethanol.
Created market with 4.3million vehicles using ethanol.
Increasing the manufacturing of ethanol-powered vehicles to 96% of domestic vehicle production.
Reduced Brazil's reliance on imported oil from 43.3% in 1985 to 21.7% in 1992
The USA Example
Over 90% of the ethanol produse in USA are made from a corn-a starch based feedstock that is easily fermented to ethanol.
In the USA, of 6.4billion liters of ethanol produce in 1998,around 3.9billion liters were consumed in the domestic fuel mix.
INDIA Needs An Ethanol Progame
INDIA is a agriculture country.35 % of farmer adopt sugarcane in farm that very large source.
In the past our government has taken number of initiatives to study the feasibility of using ethanol
The study concluded satisfactory performance of vehicles with 10% to 20% ethanol blend in gasoline.
India produces nearly 1.3billion liters of ethanol utilizing less than half of its total installed capacity, There are 295 alcohol distilleries in the country with an installed production capacity of 3918 liters.
Some of the obstructions in INDIA
Absence of a government policy
Differential state government policies on ethanol and molasses
Varied views on emission benefits
Lack of infrastructure and experience on handling gasoline-ethanol blends
Lack of awareness at all levels
Promotional measures on the part of oil and auto industries missing, thus delaying the entry of ethanol into the transport sector
Fuel Property Changes with Ethanol Addition
The addition of ethanol results in changes to the properties of the fuel.
This includes exhaust and evaporating emission. fuel economy, drivability, full load performance (power) and durability's.
Fig.(1) shows the linear increase in oxygen as the %of ethanol is increasing.
The increased oxygen in the fuel changes the stoichiometric air/fuel ratio.
Fig.2 shows how the mass air/fuel ratio corresponding to stoichiometric mixture strength changes with the addition of ethanol to gasoline.
From this figure, it is clearly seen that gasoline has a stoichiometric air/fuel ratio of approximately 14.6:1,while a 20% blend of ethanol and gasoline has a stoichiometric air/fuel ratio of approximately 13.5:1.
The changes in fuel density will change the mass of fuel delivered.
As ethanol has higher density than the gasoline, as the ethanol content is increased, the fuel mass is increased.
Fuel Economy
Fuel economy reduced when oxygenates are blend with gasoline due to the lower content of the oxygen.
Fuel economy reduction in was directly proportional to the reduction in energy content of the blended fuel when ethanol as added.
This was limited to blends of up to 10%ethanol,which shows a reduction in in fuel economy of approximately 3%when compared to gasoline only.
For higher 20%ethanol ,it is expected that this linear trend will continue.
Ethanol Blended Fuel Volatility
Evaporative emissions are influenced by the volatility of the fuel. An increase in RVP (Reid Vapour Pressure - a measure of the fuel volatility) due to the presence of oxygenates such as ethanol, will give a corresponding increase in evaporative emissions .
When ethanol is added to gasoline, the RVP of the blend is increased by about 7kPa for 5 to 10% by volume ethanol content.
The RVP gradually declines when the ethanol content exceeds 10%, and at between 30 to 45% becomes equivalent to the base gasoline volatility.