Thermal energy meters
Introduction
The calorimeter is an instrument used to measure the amounts of heat supplied or received by bodies. That is, it is used to determine the specific heat of a body as well as to measure the amounts of heat that bodies release or absorb.
The most widely used type of calorimeter consists of a closed and perfectly insulated container with water, a stirring device, and a thermometer. A heat source is placed in the calorimeter, the water is stirred until equilibrium is achieved, and the temperature rise is checked with the thermometer. If the heat capacity of the calorimeter is known (which can also be measured using an ordinary heat source), the amount of energy released can be easily calculated. When the heat source is a hot object of known temperature, the specific heat and latent heat can be measured as the object cools. Latent heat, which is not related to a change in temperature, is the thermal energy released or absorbed by a substance when changing from one state to another, such as from liquid to solid or vice versa. When the heat source is a chemical reaction, as occurs when burning fuel, the reactant substances are placed in a heavy steel container called a pump. This bomb is introduced into the calorimeter and the reaction is caused by ignition, with the help of an electric spark.
Calorimeters usually include their equivalent, to facilitate calculations. The water equivalent of the calorimeter is the mass of water that would behave the same as the calorimeter and would lose the same heat under the same circumstances. In this way, you only have to add the amount of equivalents to the water.
The calorimeter is named after Antoine Lavoisier.[1] In 1780, he used a guinea pig in his experiments with this device to measure heat production. The heat from the guinea pig's breathing melted the snow surrounding the calorimeter, showing that respiratory gas exchange is combustion, similar to a burning candle.[2].
dry charge calorimeter
Contenido
En comparación con los instrumentos posteriores la precisión era muy modesta con una incertidumbre de 2 % para la versión coaxial y 1 a 2,5 % para las versiones de guía de ondas. No obstante, estos diseños establecieron la dirección general para los siguientes instrumentos.
Nueva precisión en cargas y conectores desarrollados en los años 60 llevaron a una nueva generación de calorímetros coaxiales con mejor rendimiento e incertidumbre debajo de 0,5 % para frecuencias mayores de los 8 GHz.