First, the core principle of the calorimeter

The calorimeter is based on the law of conservation of thermodynamic energy and calculates the calorific value by measuring the heat released by the complete combustion of the fuel. The common oxygen bomb calorimeter is to fully burn the sample in a high-pressure pure oxygen environment, and the released heat is absorbed by the calorimeter system, and the calorific value is calculated by the temperature change.

Key formulas for calorific value calculation

The core formula of calorific value calculation is: Q = (C × Delta T)/m. Where Q represents the calorific value of the sample (unit: J/g or MJ/kg), C is the heat capacity of the calorimeter (unit: J/℃), which needs to be calibrated with standard materials in advance; Delta T is the temperature difference of the calorimeter system before and after combustion (unit: ℃); m is the mass of the sample (unit: g).

III. Practical operation calculation steps

1. Calibration heat capacity: Use benzoic acid with known calorific value, operate and burn according to specifications, record temperature changes, and substitute the formula to calculate the calorimeter heat capacity C.

2. Sample determination: Weigh a certain mass m of the sample to be tested, put it in an oxygen bomb, and accurately record the temperature change Delta T.

3. Calculate the calorific value: Substitute C, Delta T, and m into the formula to calculate the calorific value of the sample. If you need to convert to a high calorific value, you also need to consider the correction of the latent heat of vaporization of the combustion-generated water.

IV. Precautions

Before the experiment, ensure that the components of the calorimeter are normal and the oxygen bomb is well sealed; the sample should be weighed accurately, and the ambient temperature should be stable to avoid external heat interference and ensure the accuracy and reliability of the calculation results.