Chapter hvac engineering Fundamentals: Part 1 Introduction

9.9.1
Two-stage evaporative cooling
A two-stage evaporative cooling system (Fig. 9.30) consists of a con-
ventional cooler, as described above, preceded by a precooling section
which gets its water supply from an evaporative water cooler. As
shown on the psychrometric chart (Fig. 9.31), the precooling coil re-
duces both the wet- and dry-bulb temperatures of the air entering the
second-stage evaporative cooler, thereby decreasing the final dry-bulb
temperature and the resulting space humidity. While the system is
more costly than single-stage evaporative cooling, it may be more cost-
Equipment: Part 1
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