calorimeter is the core instrument for measuring the calorific value of fuel. Its calorific value calculation is based on oxygen bomb calorimetry. The core logic is to derive the calorific value by measuring the heat released by the combustion of the sample and combining the parameters of the instrument.

First, the core principle: energy conservation and heat conduction

The core of the calorimeter is the oxygen bomb environment - the sample is fully burned in an oxygen bomb filled with high-pressure oxygen, and the released heat is absorbed by the outer cylinder water. By measuring the change of water temperature and combining the heat capacity of the instrument, the calorific value of the sample is calculated. The key formula is:

Q=K×ΔT/m

Where Q is the calorific value of the sample (J/g), K is the calorimeter heat capacity (J/℃), Delta T is the water temperature change value of the inner cylinder (℃), and m is the sample mass (g).

Key steps in calorific value calculation

1. Heat capacity calibration: Combustion with a reference material (e.g. benzoic acid) with a known calorific value, measuring the change in water temperature, and calculating the heat capacity of the instrument K = Q/Delta T, which is the prerequisite for accurate calculation.

2. Sample test: Weigh an appropriate amount of samples to be tested (such as coal, fuel oil), put them in an oxygen bomb for combustion, record the initial temperature of the inner cylinder and the highest temperature after combustion, and calculate the delta T.

3. Formula substitution calculation: Substitute K, Delta T, and m into the formula to directly obtain the calorific value of the sample. To convert to kcal/kg, divide by 4.1868 (1 kcal = 4186.8 joules).

III. Precautions

Samples need to be ground evenly and weighed accurately to avoid incomplete combustion.

The oxygen bomb needs to be well sealed to ensure sufficient oxygen and prevent heat leakage.

The heat capacity needs to be recalibrated before each test to avoid fluctuations in the state of the instrument affecting the results.

By mastering these steps, the calorimeter can be quickly used to calculate the calorific value, providing reliable data support for fuel quality testing.