A compressor moves a certain VOLUME of air. Even though most compressor maps list airflow by mass (lbs/min), it's actually a matter of VOLUME (CFM), that has been translated to mass by assuming a certain temperature and pressure (~25C and 1 atmosphere).
So, what this means is that a compressor that maxes out at say 55lb/min airflow on it's compressor map, should be able to flow about 10% more (60 lb/min) if the inlet temperature was 0C (0C air is about 10% denser than 25C air).
Right?
Now, try and keep up here.
I imagine another big part of the limitation of the compressor is the amount of force of stacking up the air and compressing it. Although the ENGINE benefits from a intercooler, the compressor really doesn't care. It's still working hard, and making hot temps. These hot temperatures which result naturally from compression, work to expand the air, while the compressor works to contract it.
So, what if you could "intercool" the compressor itself? Add a mist of methanol/water to the inlet, which would vaporize and cool the air as it passes through the compressor? I'm still unsure on this, but wouldn't that mean a even bigger jump in the efficiency and upper limit of a given compressor, seeing as how it has to work against the air far less?
My guess here is that a compressor works on relative volume in vs out. When you see a compressor map, and one section says say 75% efficient at 60lb/min and a 3 pressure ratio. What REALLY matters, is how much volume is going in, vs going out. You get a 3x reduction in volume through compression, and gain 30% volume through heat expansion (25C in, 150C out). That's a mass boost of 2.1:1.
Now, IF the out temp of the compression process was reduced to say 40C through methanol vaporization, look what happens:
Pressure ratio of 3:1 remains
Temperature gain now only expands the air by 5%.
3*.95=2.85
So, if I'm not missing anything, the same compressor, operating at the same 3:1 pressure ratio, will be able to flow 2.85/2.1=35% more air if the air only heats up to 40C during the process instead of 150C.
Combine the gains of pre-compressor cooling to freezing temps, and the integrated cooling (actually heat gain reduction) during compression, and a compressor rated to only flow 55lb/min could flow: 55*1.1*1.35=81.675lb/min.
So, what this means is that a compressor that maxes out at say 55lb/min airflow on it's compressor map, should be able to flow about 10% more (60 lb/min) if the inlet temperature was 0C (0C air is about 10% denser than 25C air).
Right?
Now, try and keep up here.
I imagine another big part of the limitation of the compressor is the amount of force of stacking up the air and compressing it. Although the ENGINE benefits from a intercooler, the compressor really doesn't care. It's still working hard, and making hot temps. These hot temperatures which result naturally from compression, work to expand the air, while the compressor works to contract it.
So, what if you could "intercool" the compressor itself? Add a mist of methanol/water to the inlet, which would vaporize and cool the air as it passes through the compressor? I'm still unsure on this, but wouldn't that mean a even bigger jump in the efficiency and upper limit of a given compressor, seeing as how it has to work against the air far less?
My guess here is that a compressor works on relative volume in vs out. When you see a compressor map, and one section says say 75% efficient at 60lb/min and a 3 pressure ratio. What REALLY matters, is how much volume is going in, vs going out. You get a 3x reduction in volume through compression, and gain 30% volume through heat expansion (25C in, 150C out). That's a mass boost of 2.1:1.
Now, IF the out temp of the compression process was reduced to say 40C through methanol vaporization, look what happens:
Pressure ratio of 3:1 remains
Temperature gain now only expands the air by 5%.
3*.95=2.85
So, if I'm not missing anything, the same compressor, operating at the same 3:1 pressure ratio, will be able to flow 2.85/2.1=35% more air if the air only heats up to 40C during the process instead of 150C.
Combine the gains of pre-compressor cooling to freezing temps, and the integrated cooling (actually heat gain reduction) during compression, and a compressor rated to only flow 55lb/min could flow: 55*1.1*1.35=81.675lb/min.
