Abstract
Free cooling involves using a thermal energy storage
medium such as a phase change material (PCM) in order to
store the ambient “cold” during the night when ambient air
temperatures are lower compared to the indoor building
temperatures and release this stored “cold” by using a heat
transfer fluid (i.e. air) into the building during the day when
higher ambient temperatures are experienced especially during
the summer months. This paper assesses the free cooling
potential in South Africa by using a set of Rubitherm RT25HC
PCM plates. The performance of these PCM plates is assessed
by benchmarking the ambient air cooled by the PCM plates
during the day against the defined thermal comfort temperatures
requirements. The influence of varying the air flow rate on the
availability of thermal comfort temperatures at the PCM rig
outlet is also studied. The results clearly show the potential of
using PCM’s as a means of cooling higher ambient air
temperature which is experienced in hot summer months to
within thermal comfort temperatures for human occupancy in a
building.