How does the energy of air change after isothermal compression, and why?

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This post was last edited by hxm2087 on 2012-6-21 at 19:54. During compression, air pressure is increased by consuming electrical energy. At the same time, the temperature of the gas also increases. As the gas temperature rises, its volume expands, making compression more difficult; more energy is required to compress it to the same pressure. Therefore, in order to reduce the energy consumption of the compressor, cooling should be carried out as thoroughly as possible during the compression process; generally, intermediate coolers and cylinder cooling water jackets are installed to use cooling water for cooling. Under ideal conditions, the temperature of the air does not rise after compression and remains equal to its temperature before compression; this is known as \"isothermal compression\". During isothermal compression, since the temperature remains constant, the kinetic energy of the gas molecules does not change. As the pressure increases, the specific volume decreases, the distance between molecules shrinks, and the potential energy of molecular interactions decreases. Therefore, the internal energy decreases after isothermal compression of air. From the thermodynamic property chart of air, it can be seen that the specific enthalpy of air at the same temperature decreases as pressure increases. Why does compressing air consume a large amount of electrical energy? As the air pressure increases, why does the energy of the air decrease? Does this violate the law of conservation of energy? In fact, during the compression of air, in addition to receiving energy from the outside world in the form of work done on it, a large amount of heat is also released into the cooling water, which then carries away that heat. According to energy balance, if energy expenditure exceeds income, it can only be compensated by reducing internal reserves. This is the case for air during isothermal compression, where the heat released to the cooling water is greater than the work consumed by the compressor.