Biodiesel Theory
Theory:
In the production of biodiesel from cooking oils (glycerides) and methanol are combined with sodium hydroxide as a catalyst. This causes the oils to break apart and reaction of the oils with the methanol. As seen in Figure 1, this produces biodiesel (in the form of esters) and glycerol.
Figure 1: The production of biodiesel (esters) from glyceride (cooking oils) and an alcohol (methanol). In combustion, a substance can be completely or incompletely combusted. In complete combustion, a fuel is combined with oxygen to produce water and carbon dioxide. In incomplete combustion, not all of the fuel is converted into carbon dioxide. The fuel that is not converted to carbon dioxide is converted into carbon monoxide, thus making the products of incomplete combustion carbon dioxide, carbon monoxide and water.
To determine the heating value of biodiesel, a bomb calorimeter will be utilized to measure the heat produced. The first concept that this method utilizes is an overall energy balance for the fuel and water system. (1)
Where is the change in energy of a system, [J] is the energy of the fuel, [J] is the energy of the water, [J] is the heat of the fuel in the system, [J] is the heat of the water in the, [J] is the change in work of the system, [J] is the energy from the transfer of mass, [J]
Some terms in Equation two can then be canceled out due to the system boundaries. There is no work done on or by the system and no transfer of mass in or out of the system so all of those terms are zero. Finally, for a closed system, the is equal to zero. This results in the following equation: (2)
To find the heat into and out of the system the concept of the specific heat of a substance can be utilized. Where the specific heat of a substance is (3)
Where is the heat produced, [J] is the mass of the substance, [g] is the specific heat capacity of the substance, [J/goC] is the change in
In the production of biodiesel from cooking oils (glycerides) and methanol are combined with sodium hydroxide as a catalyst. This causes the oils to break apart and reaction of the oils with the methanol. As seen in Figure 1, this produces biodiesel (in the form of esters) and glycerol.
Figure 1: The production of biodiesel (esters) from glyceride (cooking oils) and an alcohol (methanol). In combustion, a substance can be completely or incompletely combusted. In complete combustion, a fuel is combined with oxygen to produce water and carbon dioxide. In incomplete combustion, not all of the fuel is converted into carbon dioxide. The fuel that is not converted to carbon dioxide is converted into carbon monoxide, thus making the products of incomplete combustion carbon dioxide, carbon monoxide and water.
To determine the heating value of biodiesel, a bomb calorimeter will be utilized to measure the heat produced. The first concept that this method utilizes is an overall energy balance for the fuel and water system. (1)
Where is the change in energy of a system, [J] is the energy of the fuel, [J] is the energy of the water, [J] is the heat of the fuel in the system, [J] is the heat of the water in the, [J] is the change in work of the system, [J] is the energy from the transfer of mass, [J]
Some terms in Equation two can then be canceled out due to the system boundaries. There is no work done on or by the system and no transfer of mass in or out of the system so all of those terms are zero. Finally, for a closed system, the is equal to zero. This results in the following equation: (2)
To find the heat into and out of the system the concept of the specific heat of a substance can be utilized. Where the specific heat of a substance is (3)
Where is the heat produced, [J] is the mass of the substance, [g] is the specific heat capacity of the substance, [J/goC] is the change in
References: Cenegal, Yunus A, and John M. Cimbala. “Heat Exchanger.” Fundamentals of Thermal Fluidsciences. 4th ed. New York, USA: McGraw-Hill Higher Education, 2012.943. Print.