Determination of Calorific values

The determination of the calorific value of natural gases is of great economic importance in gas supply. It is used to measure the calorific value (CV) of solid as well as liquid fuel. But to determine the CV of gas, one need to choose Junker's calorimeter. Besides gas calorimetry using the classical procedure of burning a gas sample, different methods are available: analytical methods which are based on the analysis of the gas sample, correlative methods which allow the calorific value to be calculated as a function of characteristic physical measurands, stoichiometric methods which make use of the almost linear correlation between oxygen required for combustion and calorific value, and state reconstruction which is based on calorific value calculation by offline simulation of the whole gas supply network.

Procedure

A known quantity of fuel sample is added in crucible.

Start the stirrer and not the initial temperature of water.

Start current through crucible and let fuel sample to burn in presence of oxygen.

Heat release during combustion of fuel is taken by water and temperature of it rises.

Goutel suggested the following formula:

calculate the higher calorific value when the percentage proximate analysis of fuel is known.

calorific value = 343.3 x fixed carbon % + α x % volatile matter kJ/kg.

The significance of calorific value is the energy or amount of heat produced as a result of the complete combustion of a unit volume of the substance. It gives the value of fuel or food in numbers which can be calculated with a formula.

The list of calorific value in fuels

Fuel	Calorific Value (Approx)
Sulfur (s)	3,955
Cow Dung	8,000
Sub-Bituminous coal	10,490
Semi anthracite	12,683
Wood	22,000
Coal	33,000
Biogas	40,000
Petrol/Diesel/kerosene	45,000
LPG/Methane	50,000

Undertand the Cp and Cv by Mayer's formula is Cp - Cv = R.

Cp = molar specific heat capacity of an ideal gas at constant pressure,

Cv is its molar specific heat at constant volume and

R is the gas constant.

Specific heat capacity of a substance is defined as the heat supplied per unit mass of that substance per unit rise in temperature.

Calorimeter

Calorimeter is the device to find the calorific value of Solid , Liquid and Gaseous Fuels.

Bomb Calorimeter

The bomb calorimeter is a type of constant-volume calorimeter used in measuring the heat of combustion of a particular reaction. also measure enthalpy changes of combustion reactions at a constant volume.