i allready know that it is the product of the compression efficiency and mechanical efficiency, but do not understand the difference between the 'overall compressor efficiency' and the 'overall efficiency' of a reciprocating air compressor. please help
2006-11-17 09:45:10 · 4 answers · asked by peterfraser270986 1 in Science & Mathematics ➔ Engineering
i think efficiency is expressed as ratio of power inputed/power outputed
ie if the compressor was rated at 800w( uses 800w) and gave out 800w in useable power then its efficiency is said to be 1/1 or 1, but no machine is that efficient, due to heat , vibration and friction etc.
if the compressor was rated at 800w and gave out 200w of usable energy it would be an efficiency of 1/4 or 0.5
2006-11-17 10:04:38 · answer #1 · answered by arnold j rimmer 3 · 0⤊ 0⤋
Compressors have several efficiencies, as noted in the appended link.
Basically, there's Adiabatic, Isothermal, and Mechanical components required to determine the solution.
I suspect that from the way your question is worded, the "overall compressor efficiency" refers to the combination of factors that only include the compressor itself. The second item "overall efficiency" refers to a SYSTEM efficiency, which would include drivers, controllers, etc that are connected to (but not actually a part of) the compressor.
By the way - it doesn't matter whether the compressor is an "air" compressor or not - or whether the compressor is reciprocating or centrifugal ... the ideas and math behind the efficiency calculations is the same.
2006-11-17 10:23:06 · answer #2 · answered by CanTexan 6 · 1⤊ 0⤋
Just a guess, but is it something to do with CFM delivery and FAD? A compressor has a cubic feet per minute output, but its useable output is actually its Free Air Delivery which is always lower than its CFM.
If a compressor has a CFM of 10, its FAD will only be about 6 or 7, and that specifies the length of useable time that an air operated tool which is connected to that compressor may be used before the delivery pressure drops to an unacceptable level.
Thus, if a tool has a consumption of 10 CFM, then the compressor may well need to be twice that output (20 CFM) in order to maintain the FAD that the tool needs to continue to operate.
2006-11-17 09:59:17 · answer #3 · answered by Phish 5 · 1⤊ 0⤋
Simply answered.
Overall efficiency is the same logic for anything and everything.
Whatever its applied to uses energy to drive itself and provides an output containing energy in the form that's used, or energy in a different form available for use.
2006-11-17 18:48:30 · answer #4 · answered by Anonymous · 0⤊ 0⤋