Award Date

1-1-2007

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Committee Member

Samir Moujaes

Number of Pages

64

Abstract

The experimental work in this research focuses on a new technique, Duct pressurization Local Leakage (DPLT) technique, developed to locate leaks in residential HVAC ducts and to quantify their leak rates. The local leakage rate determined by this technique was compared with known leakage from artificial holes. This technique was also evaluated by comparing the measured total leakages with that determined by standard duct pressurization test and Delta Q. The tests were conducted at the Air Duct Leakage Laboratory (ADLL) which has two air distribution systems and a wide range of leakage rates. The technique produces relatively small scatter and bias. The proposed technique estimates the local leakage accurately. The smoke tests confirmed the leak locations visually; A three-dimensional computational fluid dynamics (CFD) model was used to simulate fluid flow in a duct with six different leak geometries. The k-epsilon turbulence model for high Reynolds numbers flows was used for that purpose. The Reynolds numbers were varied to simulate a variety of flow conditions. The computer code was used to produce pressure drop data around the holes necessary to compute the pressure loss coefficients, as well as to produce flow field and static pressure plots that offer insight into the physics of the flow field. The flow coefficient and pressure exponent were found for different leak geometry by curve fitting the pressure and leak flow data derived from CFD simulations. Also, a correction factor was found out for an existing ventilation duct leakage formula that calculates the leakage flow. The correction factor reduced the mean absolute error from 49% to 6%.

Keywords

CFD; Ducts; Factors; HVAC Leakage; Leaks; Local; Measurement; Prediction; Residential

Controlled Subject

Mechanical engineering

File Format

pdf

File Size

1689.6 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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