What Is a Bomb Calorimeter?

A calorimeter, or calorimeter, or card meter, is an experimental device used to measure calorimetry. It can be used to measure heat changes in chemical reactions, physical changes, or to determine the heat capacity of materials. The most common are differential scanning calorimeters, thermostat microcalorimeters, titration calorimeters, and accelerated calorimeters. The simplest calorimeter is a metal container placed above the combustion chamber, which contains water and a thermometer.

In 1780, Antoine Laurent Lavoisier (French chemist) used this device to measure the heat output of a guinea pig. The heat from the guinea pig's breath melts the snow around the calorimeter, indicating that the breath is a kind of burn, similar to burning a candle. He named the experimental device a calorimeter. ^[1]

Calorimeter Adiabatic Heater

An adiabatic calorimeter is a calorimeter used to check for runaway reactions. Because the calorimeter operates in an adiabatic environment, the heat generated by the sample of test material causes the sample temperature to increase, which accelerates the reaction.

No adiabatic heater is completely adiabatic, and some of the heat is lost to the sample rack by the sample. The phi factor (a mathematical correction factor) can be used to adjust calorimetric results to account for these heat losses. The Phi factor is the specific thermal mass of the sample and the thermal mass of the individual sample of the sample holder.

Calorimeter reaction calorimeter

A reaction calorimeter is a calorimeter that starts a chemical reaction in a closed, insulated container. The reaction heat is measured and the total heat is obtained by integrating the heat flow and time. This is the industry standard for measuring heating because industrial processes are designed to operate at a constant temperature. Reaction calorimetry can also be used to determine the maximum heat release rate of chemical process engineering and to track the overall kinetics of the reaction.

There are four main methods for measuring heat in a reaction calorimeter:

1. Heat flow calorimeter: Cooling / heating jacket control process temperature or jacket temperature. Heat is measured by monitoring the temperature difference between the heat transfer fluid and the process fluid. In addition, the filling volume (ie, wet area), specific heat, and heat transfer coefficient must be determined to achieve the correct values. This type of calorimeter can perform the reaction under reflux conditions, and the accuracy is not very good.

2. Heat balance calorimeter: Cooling / heating jacket controls the temperature of the process. Heat is measured by monitoring the amount of heat gained or lost by the heat transfer fluid.

3. Power compensation: Power compensation uses a heater placed in the container to maintain a constant temperature. The energy supplied to the heater can be changed according to the needs of the reaction, and the calorimetric signal is purely derived from the electricity.

4. Constant flux: The constant-flow calorimetry (or COFLUX) is derived from a calorimetric calorimetry and uses a special control mechanism to maintain a constant heat flow (or flow) through the vessel wall. ^[2]

Calorimeter Bomb

A bomb calorimeter is a constant calorimeter used to measure the heat of combustion for a specific reaction. When measuring the response, the bomb calorimeter must withstand the tremendous pressure inside the calorimeter. Electricity is used to ignite the fuel; when the fuel burns, it heats the surrounding air, which expands and directs the air out of the calorimeter through a duct. When air escapes through the copper tube, it also heats the water outside the tube. The change in water temperature allows the caloric content of the fuel to be calculated. ^[3]

Calvet Calvet Calorimeter

The test is based on a three-dimensional flowmeter sensor. The flow meter element consists of several thermocouple rings connected in series. Correspondingly high thermal conductivity thermopile surrounds the experimental space in the calorimeter block. The radial arrangement of the thermopile ensures almost complete integration of heat. This is verified by calculating the efficiency ratio, which indicates that the average value of the heat passing through the sensor is 94% ± 1% over the entire temperature range of the Calvet calorimeter. In this setup, the calorimeter's sensitivity is not affected by the type of crucible, purge gas, or flow. The main advantage of the setup is the increase in the size of the experimental vessel and therefore the size of the sample, the calibration of the calorimeter is a key parameter and must be performed very carefully. For Calvet calorimeters, specific calibrations (the so-called Joule effect or electrical calibration) have been developed to overcome all the problems encountered with calibration with standard materials. ^[4]

Calorimeter differential scanning

In a differential scanning calorimeter (DSC), the heat flow in a sample contained in a small aluminum capsule or "pot" is usually measured differentially, that is, it is compared to the flow into an empty reference pot.

In heat flux DSC, two pans sit on small pieces of a material of known (calibrated) heat resistance K. The calorimeter's temperature linearly increases (scans) with time, that is, the heating rate dT / dt = remains unchanged. This time linearity requires good design and good (computerized) temperature control. Of course, controlled cooling and isothermal experiments are also possible.

Heat flows into the two pans by conduction. Due to its thermal capacity C _p , the flow of heat into the sample is large. The flow difference dq / dt causes a small temperature difference T at both ends of the slab. This temperature difference is measured using a thermocouple. In principle, the heat capacity can be determined from this signal. ^[5]

Calorimetric isothermal titration

In an isothermal titration calorimeter, the heat of reaction is used to perform the titration experiment. This allows to determine the midpoint (stoichiometry) (N) of the reaction as well as its enthalpy (H), entropy (S) and mainly consider binding affinity (Ka)

This technology is of particular significance in the field of biochemistry, as it helps to determine the binding of substrates to enzymes. This technology is commonly used in the pharmaceutical industry to characterize potential drug candidates. ^[5]