Coefficient of Performance (COP) is defined for many processes as output divided by input. If the quantities (and units) are the same for both output and input, COP is sometimes called Efficiency (unitless).
A typical COP is 4 (unitless) and *greater than 1* in the case of good quality heat pumps. e.g. Rate of heat delivered = 12 kW by 3 kW of electrical input to drive the compressor, fluid pumps, and air blower. Application of this concept to automobiles (or aircraft), gives "fuel efficiency" as distance divided by volume (or mass) of fuel burned which could be in the form km/L or km/kg respectively. There is nothing unique in US technology which defines output/input as a measure of performance or efficiency. Gene. ...................................... On Mon, 1 Jul 2002, Markus Kuhn wrote: > Brian J White <[EMAIL PROTECTED]> writes: > > I think km per liter would > > have been a much better choice than liters per 100km. > > There seems to be a tradition in the US marketing world, to use > reciprocal units in order to ensure that a higher number means better. I > would be curious if you have any reference for where/when this practice > originated historically. ...
