Air Compressors Info

We know from the previous section that the minimum air compressor work is achieved with isothermal compression. In practical way, we try to achieve that by involving some cooling during compression process that leads to Polytropic compression process. Normally, this can be achieved by dividing air compression into 2 stages. The first stage builds up the pressure from P1 to Px then the compressed air is cooled by the intercooler and the second stage compressor builds up the pressure again from Px to the final pressure P2. See the following figures to understand how the energy can be saved by using intercooling between each stage. Fig.1 P-v diagram of polytropic compression process with intercooling Fig.2 T-s diagram of polytropic compression process with intercooling We can see from Fig. 1 that the amount of compressor work saved is related to the pressure Px. What is the optimal value of Px that yields maximum compressor work saved? The total compressor work, for this case, is the s...

To understand how to save the energy in compressed air system , it is useful to start with theory background of how the air compressors work and how the energy is consumed. As we know from Thermodynamic principle that the compressor work is, where: rev = reversible in = input Our objective is to minimize the air compressor work that means to approach the reversible process i.e. minimize the friction, and turbulence Practical way to do this is to make v (specific volume) small by maintaining T (temperature) at low temperature during compression because v a T. In other words, to reduce the work input to a compressor, air should be cooled as it is compressed. Effect of Cooling Isentropic process: No cooling during compression Polytropic process: Involve some cooling Isothermal process: Involve maximum cooling Which process yields the minimum required compressor work? Let's consider the following equations of each process. Assumptions: All three processes are executed between the same...