Design of a Radiant Panel Cooling System for Summer Air Conditioning

Abstract

The main objective of this research was to design and investigate a radiant panel cooling system on small scale building type (office) under the central Sudan climatic conditions so as to explore the benefits of radiant cooling systems over conventional air conditioning systems (VAV systems). Transient heat conduction of building (finite difference method) was used to evaluate the simulation model. The computer program (Matlab) was used to calculate transient heat flow through the walls and ceiling (variable loads) of the conditioned space. Other heat loads of the conditioned space were determined by the standard ASHRAE method. After the cooling load was calculated, the cooling system (radiant cooling panel system) was designed. This system consists of four (1.3m x 1.05m) panels made out of aluminum sheet metal and was installed on the ceiling of the conditioned space (4.22m x 2m x 3.05m). Each panel consists of thirteen serpentine copper tubes fixed down on one side of the sheet and insulated with fiberglass at the back of the other side to prevent heat gains from the plenum. The experimental verification was achieved by using a cooling system which consists of a water chiller unit, fan coil unit (ducted fan coil unit) and radiant cooling panels. The duration of the experimental work took around one month (from 19th September to 21ist October 2006). Tests were conducted every day starting from 8 am up to 4 pm. In these tests four time intervals are selected for data recording (10am, 12pm, 2pm and 4pm) to evaluate the validity of the radiant cooling panel system. The experimental results showed that the ceiling radiant cooling panel system with dedicated outdoor air system saves power demand of 21% and 35.3% of VAV system in case if recirculation air and 100% VII fresh air are used in each respectively. In addition, the present investigation indicates that the radiant cooling system not only reduces the building energy consumption but also improve the human comfort (100% fresh air and uniform temperatures distribution) with no noise (minimum supply air is used) in the conditioned space. Finally, the ceiling radiant cooling panel system has great advantages to improve human comfort and to save power demand when compared with VAV system. This system was found to be very suitable for a hot and arid environment (Khartoum) as shown in this investigation due to the fact that Sudan with its tropical and continental location is considered one of the hottest and arid regions in the world. This fact reduces the problems of condensation on the radiant cooling panel surfaces.