PARAMETRIC STUDY OF NOZZLE GEOMETRY ON INDUCTION RATIO IN ACTIVE CHILLED BEAM SYSTEM

Abstract

The increasing global energy consumption, particularly within the building sector, necessitates the advancement of energy-efficient technologies to mitigate environmental impacts. This study focuses on Active Chilled Beam (ACB) systems, recognized for their lower energy consumption compared to traditional HVAC systems. By utilizing Computational Fluid Dynamics (CFD) simulations, this research examines the impact of ACB nozzle geometry on the system's induction ratio and the indoor airflow field, aiming to optimize energy efficiency and thermal comfort within indoor environments. The methodology encompasses the development of a simplified ACB model and a room model, excluding the heat exchanger for simplification. Variations in nozzle radius, length, and spacing were systematically analysed to determine their effects on the induction ratio and indoor airflow patterns. The study reveals that a decrease in nozzle radius and an increase in nozzle spacing significantly enhance the induction ratio, with minimal impact from changes in nozzle length. Furthermore, the indoor airflow analysis underlines the importance of nozzle geometry in maintaining comfortable wind speeds within the occupant zone, highlighting potential discomfort from airflow detachment due to over-adjustment of nozzle parameters. Limitations of the study include its reliance on numerical modelling without experimental validation and the assumption of isothermal conditions. Future work should focus on validating the numerical model with experimental data, exploring the effects of temperature differences, and investigating the influence of pressure distribution in the primary air chamber on the induction ratio. This research contributes to the development of more efficient ACB systems, with implications for the sustainable design of future HVAC systems.