What is electric calorimeter?
is generally a calorimetric instrument. An electric calorimeter consists of a combustion oxygen bomb, inner cylinder, outer Jane, stirrer temperature sensor and specimen ignition device, temperature measuring device, and control system and water. There are two kinds of general calorimeters, thermostatic and adiabatic, and their calorimetric systems are enclosed in a water-filled double jacket (outer cylinder), and they differ only in the outer cylinder and the attached automatic temperature control device, and there is no obvious difference in the rest. Various types of thermostatic calorimeters are commonly used in our power system.
Electric calorimeter application
An electric calorimeter
is an instrument for measuring the heat of solids and liquids. The structure of the calorimeter generally has four parts: outer cylinder, inner cylinder, thermometer, and stirrer. The outer cylinder of the calorimeter is used for insulation, and the inner cylinder is used to act as a reaction vessel. The thermometer of the calorimeter is used to measure the change in reaction temperature, and the stirrer is used to make the reactants mixed evenly to improve the completeness of the reaction and the accuracy of the calorimeter. The electric calorimeter is widely used in coal, electric power, chemical metallurgy, building materials, wood, petroleum, and other industries.
Structure of electric calorimeter
The main body of the calorimeter
consists of four parts: the oxygen bomb, the inner cylinder, the outer cylinder and the stirrer and calorimetric thermometer.
Oxygen bomb in electric calorimeter
The oxygen bullet in an electric calorimeter is made of heat-resistant, corrosion-resistant nickel-chromium or nickel-chromium-aluminum alloy steel, which is used for burning specimens and consists of a cartridge, a bullet head, and a cover ring. Three main properties are required.
(1) not affected by the thermal effects of high temperatures and corrosive products that occur during combustion.
(2) The ability to withstand the oxygenation pressure and the transient high pressure generated during the combustion process.
(3) The ability to remain completely gas-tight during the test.
The inner cylinder of electric calorimeter
The heat released from the combustion of the specimen in the oxygen bomb is absorbed by the water in the inner cylinder, which makes the water temperature rise. The inner tube is made of copper, brass, or stainless steel, and the cross-section can be a round diamond or another appropriate shape. The cylinder is filled with water 2000~3000mI. to be able to submerge the oxygen bomb (except the inlet and outlet valves and electrodes). The outside of the inner cylinder should be electroplated and polished to reduce the radiation effect on the outer cylinder.
The outer cylinder of the electric calorimeter
The outer cylinder is used to keep the ambient temperature of the heat measurement system constant (the same as the room temperature) and is a double-walled container made of metal with a top cover. The outer wall is round, and the shape of the inner wall depends on the shape of the inner cylinder; in principle, the two should be kept 10 to 12 mm apart, the bottom of the outer cylinder has an insulating support, to place the inner cylinder.
(1) The outer cylinder of the thermostatic calorimeter. The thermostatic calorimeter is configured with a thermostatic external Jane. The heat capacity of the outer cylinder filled with water should be not less than 5 times the heat capacity of the calorimeter, to keep the temperature of the outer cylinder constant during the test. The outside of the outer cylinder can be insulated to reduce the influence of room temperature fluctuations. The thermometer used for the outer Jane should have a minimum index value of 0.1K.
(2) Adiabatic electric calorimeter outer cylinder. Adiabatic calorimeter configuration adiabatic outer cylinder. The outer cylinder is equipped with a heating device. Through the automatic temperature control device, the outer cylinder's water temperature can closely track the temperature of the inner cylinder. The water in the outer cylinder should also be circulated in the special double-layer cover. The sensitivity of the automatic temperature control device should be able to achieve the ignition before and after the end of the inner tube temperature to maintain stability (5min temperature change on average not more than 0.0005K/min); in a test of the heating process, the heat exchange between the inner and outer tube should not exceed 20J.
Electric calorimeter stirrer
Equipped with an agitator in the inner cylinder to ensure uniform water temperature in the inner cylinder. Propeller type or other forms, speed 400 ~ 600r/min is appropriate, and should be kept stable. Stirring efficiency should be able to make the heat capacity calibration from ignition to the end of the time not more than l0min, but also to avoid generating too much heat of stirring (when the temperature of the inner and outer Jane and the same room temperature, the heat generated by continuous stirring l0min should not exceed 120J).
The temperature measurement error of the inner cylinder is the main source of the error of heat measurement, and it is especially important for the correct use of the thermometer.
significance. The following two types of thermometers can be used for this purpose.
(1) glass mercury thermometer. Commonly used glass mercury thermometer has two kinds: a fixed temperature range of precision thermometer; a variable temperature range of Beckman thermometer. The minimum division of the two should be 0.01K, the use of the correction value should be based on the measurement authority certificate to do the necessary correction, both thermometers should be scale correction (Beckman thermometer called aperture correction). Beckman thermometer in addition to this correction value there is a correction value called the average index value.
(2) digital calorimetric thermometer. Need to be certified by the metrological authorities, to prove its resolution of 0.001K, temperature measurement accuracy of at least 0.002K (after correction), in order to ensure the accuracy of temperature measurement.
Electric calorimeter working principle
How the electric calorimeter works: hot water (cold water) supplied from a heat source flows into a heat exchange system (radiator, heat exchanger or a complex system composed of them) at a higher (lower) temperature and out at a lower (higher) temperature, in the process of which heat is released or absorbed to the user through heat exchange (note: this process includes the heating system and cooling system energy exchange process). As the water flows through the heat exchange system, the amount of heat released or absorbed by the system is calculated and displayed by a calculator based on the flow rate given by the flow sensor and the supply and return water temperature given by the paired temperature sensor, as well as the time the water flows through.
Types of electric calorimeter
There are direct calorimeter and indirect calorimeter.
Direct calorimeter is a device for direct measurement of the heat generated by the combustion of nutrients, or for the measurement of the heat emitted by an organism placed in a closed chamber.
Indirect calorimeter is a device that measures the gas exchange and calculates the energy metabolism from the results. The main instruments of the indirect calorimeter are the respirometer of Krogh or respirometer and the Be- nedict type respirometry device. In order to collect the breathing gas, the so-called "Douglas bag" is used. There are also methods of measuring O2 or CO2 using gas analyzers. Gas analyzers include the Haldane type analyzer and its modified Laoyan type analyzer.
How to install electric calorimeter?
a. The electric calorimeter must be cleaned before installation.
b. The electric calorimeter is a precision instrument, so it must be installed carefully, and it is forbidden to lift and drag the meter head and sensor wire.
c. The direction indicated by the arrow on the meter body of the electric calorimeter sensor indicates the direction of water flow, and theoretically, it is not allowed to be installed in the opposite direction.
d. The front end of the electric calorimeter pipeline must be equipped with a filter of the corresponding caliber.
e. The installation of the electric calorimeter should ensure that there is at least 10 times the diameter of the straight pipe section upstream and at least 5 times the diameter of the straight pipe section downstream in the direction of the water flow of the calorimeter pipe.
f. Both ends of the calorimeter must be equipped with valves of corresponding diameters and be separated from the calorimeter for cleaning and maintenance of the calorimeter in the course of use.
g. The calorimeter has a pair of temperature sensors for the water inlet and outlet respectively. Install the red-labeled temperature sensor on the inlet pipe and the blue-labeled temperature sensor on the outlet pipe. The temperature sensor probe inserted into the pipe location should be in the center of the pipe cross-section (temperature sensor as shown below inserted in some ways.
h. The standard wire length of the temperature sensor of the electric calorimeter is 3 meters, and it can be lengthened according to the actual length in case of special circumstances during installation, and the situation should be explained to the manufacturer when ordering, and the lead length of the temperature sensor should not be increased or decreased at will by oneself.
i. Seal each connection after the installation of the calorimeter is completed, especially the sensor is inserted into the pipe.
How to order electric calorimeter?
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