The influence of pulsation with different amplitudes on the heat transfer rates in a double-pipe heat exchanger where a coiled wire inserts around the outer surface of the inner tube is investigated. The heat transfer and pressure drop characteristics were investigated for a coiled wire inserts with different pitch values in absence of pulsation. Pulsation frequencies that were produced by using a reciprocating device ranged from 140 to 260 cycles per minute (2.3–4.3 Hz). Five different displacement amplitudes were
used where the stroke length of the reciprocating piston was varied from 60 to 185 mm.