Compression Effects on Pressure Loss in Flexible HVAC Ducts

Abstract

A study was conducted to evaluate the effect of compression on pressure drop in flexible, spiral wire helix core ducts used in residential and light commercial applications. Ducts of 6", 8" and 10" (150, 200 and 250

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“…Culp and Cantrill (2009) presented pressure loss data for nonmetallic wire-wound flexible ducts having compressions ranging from 4% to 45%, which had the maximum allowable sag between joist supports. Their data extended the PDCF correlations of Abushakra et al (2004) to larger diameter flexible ducts. Kulkarni et al (2012) measured pressure losses in one diameter of an impermeable fabric duct used in air dispersion systems.…”

“…It was determined that minor differences in corrugation profiles and seam pitches did not have a significant influence on the measured pressure loss, since the resulting absolute roughness values differed by less than 15% compared to the results presented by Kulkarni et al (2009). Abushakra et al (2004) investigated the influence of compression on pressure loss measured in wire-wound flexible ducts. These ducts are typically used in residential and light commercial applications.…”

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“…However, these empirical formulas may not be suitable for all the duct systems. For instance, the empirical formula for the flexible duct proposed in [35] exhibits considerable variation in the calculation of pressure drop because of differences in manufacturing, materials, test setup, inner liner nonuniformities and installation [26]. Besides, due to the complex fluid interactions and coupling effects, q-∆p relationship in the duct system is very complicated and difficult to formulate analytically.…”

“…These empirical formulas may not be suitable for all the duct systems. For instance, the empirical formula for the flexible duct proposed in [35] exhibits considerable variable in the calculation of pressure drop because of differences in manufacturing, materials, test setup, inner liner nonuniformities and installation. Original duct layout may be lost, or the current component size may be changed when retrofitting the air duct system.…”

“…It is usually difficult to accurately formulate the relationships between pressure drop and airflow for all the fittings in duct systems. For instance, the calculation model for the flexible duct proposed in [35] exhibits considerable variation in the estimation of pressure drops under different installed conditions. Different from the physical modeling method, data-driven method does not establish complicated physical models but uses machine learning techniques to learn complex relationships from the data.…”