Analysis of a low-temperature small approach open cooling tower integrated with radiant cooling and displacement ventilation for space conditioning in temperate climates

ABSTRACT Evaporative cooling, using cooling tower systems, has the potential to offer an alternative approach for producing high temperature chilled water, particularly for buildings located in temperate climates. The current paper examines the performance of an integrated cooling system, where an open forced draught counter flow cooling tower is used for the provision of chilled water for a radiant cooling and displacement ventilation system. For this purpose, a low temperature low approach direct evaporative cooling tower is used which can provide cooling water with low approach temperatures (1-3 K), which defines the temperature difference between the tower water outlet temperature and ambient wet bulb temperature. The performance of the proposed cooling system has been investigated for internal buildings loads up to 66 W·m-2 in order to examine the limitations of the cooling system. Space thermal comfort conditions and system performance metrics were assessed for four different temperate climate types as follows: cool and dry (Helsinki), cool and semi-humid (Birmingham), warm and dry (Prague), and warm and humid (Paris). The assessment shows that for the proposed system, where a radiant floor was used, can provide acceptable thermal comfort conditions for approximately 80% of the occupant hours over the respective cooling seasons.