<p>In pumped hydro compressed air energy storage systems, the heat exchange performance between air and water significantly affects the thermodynamic performance. This study proposes an enhanced heat transfer method by adding trays and investigates the effects of parameters such as the number of trays, tray diameter, and tray mounting height. First, the working principle of the heat transfer method when adding trays was clarified, and a mathematical model was established. Second, the effects of the number, diameter, and mounting height of the trays were analyzed. Finally, the thermodynamic, energy, and exergy performances of the system without trays, Tank 1 with trays, Tank 2 with trays, and Tanks 1 and 2 with trays were compared. The results show that the heat transfer between air and water is enhanced and the variation in air temperature is reduced when Tanks 1 and 2 have trays. The number and diameter of trays significantly affected the thermodynamic performance of the system, whereas the impact of the tray mounting height was not significant. By installing 30 trays uniformly in Tanks 1 and 2, the temperature variations in Tanks 1 and 2 were reduced by 8.2% and 15.4%, respectively; additionally, the round-trip and exergy efficiencies of the system were improved by 1.4% and 1.3%, respectively.</p>