A contaminated supply air system may have an adverse effect on indoor air quality. The aim of that study was to evaluate the effectiveness of different protective actions in achieving a clean supply air duct system on the one hand and to find out the location in the ductwork where most of the duct is accumulated. Measurements were made and presented in tables.
It appears that dust accumulation can be partly avoided by ducts protection during the whole of the construction transportation and storage phases and that no ducts with residual oil on the inner surface should be used.
In air-based systems, ducts deliver heat and cool air to conditioned spaces. Taking extra time to properly seal ducts during the installation along with repairing and patching leaks in HVAC duct systems will save cooling, heating and fan energy. With aerosol-sealing technology higher performance ducts in new and existing buildings potentially exist.
This paper presents the results of 23 experiments during which reinforced spiral ducts were submitted to underpressure until they collapse. Experiments were operated with different duct diameters, reinforcement spacing, material and duct thickness. Results were analyzed and led to an equation for estimating the collapse pressure of such ducts.
A model for air flow inside ducts with leakages has been established from the equations governing the variation of total pressure and velocity along the duct. It was found that duct performance could be expressed as a function of two dimensionless constants, allowing the calculation of the required total pressure and velocity in the duct.
Ventilation, air conditioning and air heating systems are of vital importance for the health and comfort of residents and other building users. However, there exists a substantial body of literature that shows that HVAC systems performance can be greatly affected by inferior quality ductwork. To avoid these problems, it is important to pay greater attention to the design, construction, installation, and maintenance of ductwork systems, bearing in mind that the primary functions of the HVAC systems must be fulfilled.
This paper presents the results of a field study on five HVAC duct systems in France. The principal objectives of this work were a) to evaluate the extent of duct leakage in those systems; b) to compare design and actual fan flow rates; c) to evaluate the thermal energy losses in the air ducts. The ductwork airtightness, measured by fan pressurisation method, was found to be in general well above the leakiest EUROVENT 2/2 class (class A), yielding unacceptable uncontrolled airflows. Fan airflow rates were measured with the constant injection tracer gas method.
In this paper, a literature survey on rectangular and round ventilation ducts is presented. The comparison is based on two important aspects: pressure drop and noise radiation. The pressure losses in the ductwork should be kept as low as possible without jeopardizing proper control of the flow rates in the system. Pressure loss through a rectangular duct is significant higher than a volumetrically equal round one. The higher the aspect ratio, the higher-pressure loss in the rectangular system.
In this work, experiments were carried out to estimate deposition rate of 5µm particles powder in large cylindrical straight ducts for different diameters. Two types of ducts were compared: rigid ducts and flexible ducts. Results are compared to theoretic
The Airways project was set up to provide design guidance and maintain afficient air duct systems, and to bring to light the energy saving opportunities in parallel with health, safety and comfort issues. The results of this work have been published in a book targeted at decision-makers concerned with inddor climate issues. It provides condensed information on better air duct system design and how this can be achieved.