Effects of Air Supply Terminal Devices on the Performance of Variable Refrigerant Flow Integrated Stratum Ventilation System: An Experimental Study

Yat Huang Yau,Altaf Hussain Rajpar,Umair Ahmed Rajput,Natalia Lastovets

doi:10.3390/en15041265

Abstract

A variable refrigerant flow integrated stratum ventilation (VRF-SV) system was proposed as an energy efficient substitute for conventional central cooling systems for buildings. The novel system provided conditioned air to enclosed spaces with high indoor air quality and thermal comfort. This study investigated the effects of different types of ASTDs on the performance of the VRF-SV hybrid system. The performance was experimentally evaluated with five air terminal types, including bar grille, double deflection grille, jet slot, perforated and drum louver diffusers. The evaluation was carried out using standard indices: temperature and velocity distribution, airflow pattern, effective draft temperature (EDT), air distribution performance index (ADPI), thermal sensation vote and comfort feedback survey. The results indicated that the ASTD type had a significant impact on airflow pattern. Furthermore, the bar grille diffuser provided the occupants with greater thermal comfort and acceptable indoor environment. Almost all the EDT values determined in the breathing zone in the case with bar grille diffuser found under the satisfactory range, i.e., −1.2 < K < 1.2. Based on these values, the ADPI for bar grille diffuser was calculated as 92.8%. Thus, the bar grille diffuser is recommended to be installed with the VRF-SV hybrid system in buildings.

Highlights

Increasing concerns about high indoor air quality (IAQ) and excessive energy use in built environments [1,2] demand continuous development of efficient air conditioning and mechanical ventilation (ACMV) systems
As the major shareholder of a building’s energy consumption, an ACMV system is comprised of two different systems: the air conditioning system and the mechanical ventilation system [3]
The results suggested that the adaptation of different geometries for air supply terminal devices (ASTDs) improved the thermal conditions of the ventilated zone

Summary

Introduction

Increasing concerns about high indoor air quality (IAQ) and excessive energy use in built environments [1,2] demand continuous development of efficient air conditioning and mechanical ventilation (ACMV) systems. ACMV systems in buildings are utilized to remove excess heat from indoor spaces and to replace polluted indoor air with fresh outdoor air. As the major shareholder of a building’s energy consumption, an ACMV system is comprised of two different systems: the air conditioning system and the mechanical ventilation system [3]. The most common central ACMV systems are chiller-based cooling systems and variable refrigerant flow (VRF) system. The VRF systems have grown more popular in buildings as a viable substitute to conventional central chiller-based systems due to their higher part load energy efficiency and individualized thermal control [5].

Methods

Results

Conclusion