Air Distribution Institute (ADI), initiated a duct efficiency study being conducted at Texas A&M University which began in the spring of 2004. ADI, TXU Electric Delivery, ASHRAE and Lennox Industries are co-funding the research project. Recommendations from this study will have a positive impact on the energy efficiency and overall quality of new homes for years to come.
This research study will:
This study measured airflow static pressure losses through non-metallic flexible ducts in compliance with ASHRAE Standard 120-1999, Methods of Testing to Determine Flow Resistance of HVAC Air Ducts and Fittings (ASHRAE 1999).
Indoor Environment Department, Lawrence Berkeley National Laboratory, Bass Abushakra, et al.
An experimental study was conducted to evaluate the pressure drop characteristics of residential duct system components that are either not available or not thoroughly (sometimes incorrectly) described in existing duct design literature. The tests were designed to imitate cases normally found in typical residential and light commercial installations. (Click link above for full copy of study paper)
Fully stretched, 4%, 15% and 30% compressed 6” flexible duct configurations were simulated using CFD software under various volumetric air-flows. CFD simulation results showed close proximity to laboratory experiments for fully-stretched and 30% configurations. This paper to be published in ASHRAE Transactions 1-07.
Non-metallic flexible duct products have achieved wide usage in today’s Heating Ventilating and Air-Conditioning (HVAC) applications, due to their advantages of cost and installation, over metallic ducts. Despite the advantages, an important factor in HVAC duct design is to attain minimum pressure loss throughout the distribution line. Compared to the straight ducts, the compression in flexible ducts results in increased pressure loss thus increased energy consumption.