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Texten du hänvisade till borde ju stämma, då det verkar vara USA's flottas sjöingenjörs manual..
http://www.hnsa.org/doc/pdf/engineman1.pdf
"When an engine is operating under part load,
it has a lower mechanical efficiency than when
operating at full load. The explanation for this
is that most mechanical losses are almost independent
of the load, and therefore, when load
decreases, ihp decreases relatively less than bhp.
Mechanical efficiency becomes zero when an
engine operates at no load because then bhp = 0,
but ihp is not zero. In fact, if bhp is zero and the
expression for fhp is used, ihp is equal to fhp.
To show how mechanical efficiency is lower
at part load, assume the engine used in preceding
examples is operating at three-fourths load. Brake
horsepower at three-fourths load is 900 × 0.75
or 675. Assuming that fhp does not change with
load, fhp = 443. The ihp is, by expression, the
sum of bhp and fhp."
Men nu kika jag lite på en text där en professor från MIT skrivit
"Since the friction power includes the power required to pump gas into and out ofthe engine, mechanical efficiency depends on throttle position as well as engine design and engine speed. Typical values for a modern automotive engine at wide-open or full throttle are 90 percent at speeds below about 30 to 40 rev/s (1800 to~2400 ev/min), decreasing to 75 percent at maximum rated speed. As the engine is throttled, mechanical efficiencydecreases, eventually to zero at idle operation."
http://www.scribd.com/doc/27767235/Inte … -B-heywood
Nu hittade jag ju iof svaret jag letat efter om jag förstått det riktigt?
Men det ser ju onekligen ut som att dem talar mot varandra.. ?
