Air Compressors Info

Compressed Air Energy Storage (CAES) is a way to store energy generated at one time for use at another time. At utility scale, energy generated during periods of low energy demand (off-peak) can be released to meet higher demand (peak load) periods. Compression of air generates a lot of heat. The air is warmer after compression. Decompression requires heat. If no extra heat is added, the air will be much colder after decompression. If the heat generated during compression can be stored and used again during decompression, the efficiency of the storage improves considerably. There are three ways in which a CAES system can deal with the heat. Air storage can be adiabatic , diabatic , or isothermic : Adiabatic storage retains the heat produced by compression and returns it to the air when the air is expanded to generate power. This is a subject of ongoing study, with no utility scale plants as of 2010. Its theoretical efficiency approaches 100% for large and/or rapidly cycled devic...

An air compression is a means by which one type of energy is converted to another. During this conversion certain losses occur because of the rise in temperature of the air as it compressed. In general practice, the air is stored in a receiver and heat is lost both in the receiver and pipe lines running to equipment. Since the rise in temperature of the air is a direct loss of energy. We want to keep it down to a minimum. The ideal method is to compress air isothermally but this is impossible in practice owing to lack of time necessary to affect transfer. Water jackets and inter-cooling can be used to keep the temperature down. These have the effect of reducing the compression index (n) to something less than 1.4. When air is compressed to a pressure to exceeding about 4 bar it is usual to compress it in stages, with intercooling between each stage. This considerably reduces the total amount of work required on the air. For two stages compressing, the air is compressed in the first...

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...