Neutral Air Units with Heat Pipes in Chilled Water Systems

INTRODUCTION
With today’s higher ventilation requirements and more efficient buildings, moisture becomes a higher percentage of the total load that a mixed air handling unit must handle. What happens? Both the supply air dry bulb temperature and supply
air dewpoint rise, reducing the supply air’s sensible cooling capacity and resulting in a higher indoor relative humidity. Plus, cooling must be provided at all times so wet untreated air won’t be introduced into the space. The solution is to have dedicated outside air units that supply one or more zones with dry outside air, with terminal units designed primarily for the sensible loads.
Fundamentally, dedicated outside air units are used to provide the correct ventilation amount per ASHRAE 62.1 under all operating conditions, and to reliably and energy efficiently remove the bulk of the total moisture load. Further, the design engineer is tasked to design the rest of the system to meet ASHRAE 90.1. Because the dedicated outside air units cool, heat, dehumidify and provide filtration, they are often also given the term dedicated outside air systems (DOAS).