Numerical Analysis of Two Air Conditioning Systems for Thermal Comfort in School Classrooms in Oman: Stratum Versus DX Split Systems

Abstract

In Oman, air conditioning is required in public classrooms to ensure thermally comfortable conditions for users, considering the harsh hot climate. In general, air conditioning is provided by conventional mechanical systems, such as split units that consume a considerable amount of energy. Besides the environmental consequences, this practice takes a significant portion of the governmental budget, as public-school operation cost is funded by the government. Increasing the thermostat setting combined with raising air velocity is promising in maintaining thermally comfortable classrooms with reduced cooling energy. Increasing air velocity is possible by ventilation systems, including the stratum system, where thermal comfort is achieved by directing the airstream toward the upper part of the human body. This paper reports the findings of numerical simulations using STAR CCM+, a Computational Fluid Dynamics (CFD) software. A numerical model of a typical classroom was generated in STAR CCM+ and was then validated using experimental data conducted for an actual classroom. The validated model was utilized to explore the effect of applying 15 ventilation scenarios, including a stratum ventilation system. The results showed that the conventional air conditioning systems achieved thermal comfort at several spots within the domain, but have a risk of the thermal draft. On the other hand, the stratum ventilation system achieved better thermal comfort at relatively higher air temperature compared to the conventional air conditioning systems. The results inferred that the stratum system might need lower energy consumption than the traditional cooling system.