Volumetric efficiency

[5] This equivalent volume is commonly inserted into a mass estimation equation based upon Boyle's Gas Law.

This happens when a favorable alignment of the pressure wave in the inlet (or exhaust) plumbing improves the flow through the valve.

Two-stroke engines are very sensitive to this concept and can use expansion chambers that return the escaping air-fuel mixture back to the cylinder.

This is desirable since advanced designs need to cram increasing functionality into smaller packages, for example, maximizing the energy stored in a battery powering a cellphone.

Besides energy storage in batteries, the concept of volumetric efficiency appears in design and application of capacitors, where the "CV product" is a figure of merit calculated by multiplying the capacitance (C) by the maximum voltage rating (V), divided by the volume.

The concept of volumetric efficiency can be applied to any measurable electronic characteristic, including resistance, capacitance, inductance, voltage, current, energy storage, etc.