Heat, work, energy and power
Heat and work are both forms of energy which can be passed between objects or systems. Heat transfer is closely linked temperature (or the temperature difference)that exists between two or more objects. In itself heat is always transferred from the object to the high temperature in objects with a lower temperature. Heating of water in a saucepan on the stove, is a good example from everyday life, and heat transfer. Plate plate is hot and the heat is transferred from a plate through the bottom of the pot and water. Transfer of heat to water causes the water temperature to rise. In other words, heating object is the same as the transfer of energy (heat) to the object.
In many practical applications arises the need to lower the temperature of the object, instead of increasing it. In the example above, this can only be done if you have another object with a temperature lower than the object you want to cool. Combining these two objects are in contact will lead to the transfer of heat from an object that you want to chill and, consequently, its temperature decreases.
In other words, the cooling of the object is the same as the transfer of energy (heat) from the object.
The transfer of work, as a rule, is connected with the use of mechanical shafts as one of rotating electric motor or internal combustion engine. Other forms of work transmission is possible, but the use of a rotating shaft is the main method used in refrigeration systems.
As already mentioned, as heat and work is a form of energy. Methods to transfer between different objects, but for the process with both heat and work transfer the amount of heat and work transfer that determines the outcome of the process.
Sl-Joule is a unit of [J] is used for quantitative assessment of energy, heat and work. The amount of energy needed to raise the temperature of 1 kg of water from 15 to 16 C-4.Id 187. In 4.178 kJ can be transferred in the form of heat or work, but the heat will be used most often a practical solution in this case.
There are differences in how much energy is required to raise the temperature of various substances by 1 K. For 1 kg of pure iron applications.
0.447 kJ need while 1 kg of atmospheric air is the only application. 1.0 kJ need. The property that makes iron and air with different relation to energy for causing an increase of the temperature, is called specific heat". It is defined as the energy required to raise the temperature of 1 l per 1 kg of the substance. The device for specific heat is j/kg K.
The speed with which energy is called power. Sl-a unit of power-Watt (W). Example:
If 10 J moves per second, the speed of transmission of energy declared a 10 J/s = 10 W SI choice of power supply is to transfer heat and work. In other parts of the system of heat transfer and can work in different units...
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Chillers