R-1234yf absorbs slightly less energy per unit of flow in a refrigerant cycle compared to R-134a. In order to compensate for that differential, yf systems utilize an Internal Heat Exchanger (IHX). The IHX (sometimes called a Suction Line Heat Exchanger ( or SLHX )), helps to increase the performance level of yf systems to match those of R-134a systems.
The IHX is a simple “tube within a tube” device which transfers heat between the low pressure and the high pressure flow circuits. It has no moving parts. It simply works by the movement of the hot liquid refrigerant from the high side of the system flowing through the outer tube at the same time the vaporized refrigerant from the low side of the system flows through the inner tube. This process causes a heat transfer in which the high-temperature liquid refrigerant from the high side is subcooled prior to entering the H-Block (also called a ThermoExpansion Valve or TXV) and the cold vapor refrigerant from the low side is superheated before heading to the compressor.
This process increases the efficiency of the yf refrigeration cycle and improves overall system performance.