According to the preceding analysis, the cooling capability of
the injection loop, which is directly related to the mass flow
rate in the injection loop, restricts decreases in the optimal
injection pressure and increases in the cooling capacity.
Therefore, the design methods to increase the refrigerant
mass flow rate in the injection loop will enhance the cooling
capacity of the system. Therefore, the design principle for the
injection tube is clear: shorten the injection tube and enlarge
the diameter of the injection tube. For shortening the injection
tube, the scroll compressor with an economizer attached to
the shell is a typical case (Perevozchikov and Doepker, 2003).