The injection port causes the most significant pressure drop in
the injection loop, so decreasing the pressure drop of the
injection port is significant to decreasing the overall pressure
drop in the injection loop. However, the radial size of the
injection port should be smaller than the thickness of the
scroll wrap to avoid inner leakage between different pockets,
so the effort to enlarge the area of the injection port should be
focused on the tangential dimension. Under these constraints,
hybrid injection ports following the scroll profile are developed,
such as the crescent injection port.