Theory of air compression
Air is not a perfect gas but for practical purpose the laws relative to perfect gases may be applied to it. Boyle’s law states that: The absolute pressure of a gas varies inversely as the volume, provided the temperature remains constant. p V = a constant where: p = pressure in bar, V = volume in m 3 . Charles’ law states that the volume of a gas under constant pressure, or the pressure of a gas under constant volume, varies as the absolute temperature. Therefore V varies as T, and p varies as T where T is the absolute temperature. If the two laws are combined, we get: p V / T = constant The constant is usually denoted by R and therefore: p V = R T It can be shown that the value of the constant R applicable to air is 287.0 J/(kg K). The relation between the pressure and volume of air during its expansion and compression may be represented by: p V n = R T where ‘n’ has value which depends on the addition or subtraction of heat during the process . When the te...