Diesel Oil
February 14, 2008 – 10:48 pm
Diesel is one of the fractional distillate obtained during distillation of crude oil or petroleum. It is generally called petrodiesel, as it is obtained from petroleum, to differentiate it from other forms of diesel which are obtained from sources like biomass. It is obtained between temperature range of 200 °C and 350 °C during fractional distillation at atmospheric pressure. It has a density of around 850 grams per liter which is 15% less than that of petrol or gasoline with a calorific value of around 41 mega joules per liter which is also around 15% less when compared to the calorific value of petrol. Diesel is primarily used as a fuel in specially designed diesel engines which were invented by Rudolf Christian Karl Diesel, a German engineer and patented in 1892. Initially Coal Dust was used as fuel in Diesel engine and after that vegetable oils were experimented as fuel.
First diesel engine was commercially built by Adolphus Busch in the United States. After the end of World War I diesel engines which were used in submarines were made to adapt for peacetime economy by soldiers who operated these engines. ”Semi-Diesel’ engines were manufactured by modifying these diesel engines which were used in trucks in 1930s. Fuel injection systems were started to develop in 1922 by Robert Bosch and by 1927 an acceptable and efficient injection pump was produced. The demand for this pump was very large and manufacturing was outsourced to France and England to meet the demand.Diesel regulations were introduced in the late 1960s which further strengthen the development of better diesel engines with less emission and improved fuel economy.
The composition of diesel basically has major portion of saturated hydrocarbons such as paraffins and cycloparaffins and some portions of aromatic hydrocarbons such as alkylbenezenes and naphthalenes. It is also believed that diesel oil also contains some microbes which are capable of survival in closed tank and can feed on diesel fuel.
Diesel contains a high level of pollutants as compared to petrol which require it to undergo additional filtration. Since it can also be used as heating oil its demand in cold countries is quite high as compared to petrol and as result diesel is priced higher than gasoline in UK and many parts of US. Higher energy content of diesel and the internal efficiency of diesel engine make diesel a better fuel for cars which provides better economy and causes about 31% less polluted emissions as compared to gasoline.
Due to strict emission standards being imposed world over, the world is looking for cleaner fuels. Synthetic diesel has also proved to be cleaner fuel as compared to petrodiesel as it emits 30% less pollutants. Synthetic diesel is produced by drying and gasifying garbage, sewage sludge, straw, wood and corn which results in synthetic gas. This gas after purification goes through Fischer-Tropsch process which results in synthetic diesel by converting carbon monoxide and hydrogen into liquid hydrocarbons. Natural gas can also be used to produce synthetic diesel. Bio-diesel has also come up as an alternative fuel to conventional diesel which is produced from vegetable oils.
Over the last two decades the diesel technology has shown substantial improvements. Dynamics of innovations in diesel technology has been quite high in recent years. Evolution of direct injection technology has bought breakthrough in diesel technology which has resulted in improved efficiency of energy usage by 15-20% by improving injectors and increasing pressure of injection. Many additives are being used with diesel to improve its energy content and provide better fuel efficiencies. Presently Research and Developments in the fields of diesel technology are focusing on reductions of emissions which can be achieved only on the cost of reduced energy efficiency. Most of the current Research and Development work in field of diesel technology is focused mainly at marine transport and automotive transport and railways is also expected to follow.