Calorimetry

Calorimetry refers to the measurement of quantities of heat which are coupled to biological, chemical or physical processes, and may be both exothermic and endothermic. For determining a calorimeter is used. A distinction is made between direct and indirect calorimetry. Was justified this science in 1756 by Joseph Black, a professor of physics at the University of Glasgow and student of William Cullen, the inventor of the first, nor purely experimental ice machine.

Direct calorimetry

In the direct calorimetry heat quantities are determined by means of a calorimeter. This method is also suitable for measuring the energy expenditure of an organism.

Historical Tierkalorimetrie

The first such Tierkalorimeter was built by Antoine Laurent de Lavoisier ( see Fig.) The system, designed for a guinea pig calorimeter represents the core of a ball, which was surrounded by two double-walled shells. Both dishes were filled with ice cubes. The outer shell was used to isolate the device and to make the interior of a closed system. From the outside entering the device heat is to melt the ice in the outer shell is required. Thus the partition wall between the outer and inner shell remains constant at 0 ° C, as long as there is ice present in the outer shell. The ice in the inner shell is then used to measure the heat production of the animal. The amount of heat formed by the animal is required to melt the ice. The melted water flows off at 0 ° C. The leaked meltwater amount multiplied by the heat of fusion is used as a measure of the votes from the animal heat. Is assumed here that the body heat of the animal remains constant.

Indirect calorimetry

In indirect calorimetry, the heat released amount is calculated indirectly via the measured oxygen consumption. From the amount of oxygen that a reaction or organism is used, for example, and the equivalent ( eg oxykalorisches equivalent in metabolic reactions) can be calculated back to the heat released. This is useful especially for large creatures such as humans.

Gaskalorimetrie

The Gaskalorimetrie is a method for determining the calorific value of a gas by combustion of a gas sample.

The calorimeter is divided into the following classes according to the method used:

• Combustion of a gas sample in a calorimetric bomb
• Combustion of the gas in the open flame of a gas burner,
• Combustion without a flame on a catalyst.

Swell

• S. Silbernagl, A. Despopolous: Pocket Atlas physiology. 7th edition, 2007, ISBN 978-3-13-567707-1.
• Ulrich Wernekinck: gas measurement and gas billing. 2005, ISBN 978-3-8027-5617-7.