Improving the efficiency of vapor-compression systems has justifiably focused on the electro-mechanical devices that actually consume energy, such as compressors and fans, but more attention is now being paid to heat exchangers, those passive, unheralded components that play a key role in overall system efficiency. It’s actually a dual role, as one heat exchanger rejects heat on the condenser side of the system and another heat exchanger absorbs heat on the evaporator side.