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

62

Abstract

The experimental work focuses on a new technique that is developed to identify and quantify the local air leakage rates in residential HVAC ducts. The technique is based on duct pressurization test (ANSI/ASHRAE standard 152/2004) along with a zone bag to create artificial restrictions. The experiments were conducted at the Air Duct Leakage Laboratory (ADLL). ADLL, which was solely built for conducting experiments on air duct leakage, has two duct systems with different configurations. The technique was validated by comparing the results of the new technique with a baseline technique developed at ADLL. In addition, the technique was evaluated with the existing and most commonly used techniques like Duct pressurization and Delta Q techniques for total air leakage measurement. This report includes the experimental work and the results of the new technique that was developed at ADLL. The results showed that the developed technique gives a good estimation of local and total leakages; On the Computational Fluid Dynamics analysis part, models were created to simulate fluid flow in ducts that are deformed due to constrictions during installations. Four different duct runs with deformations were modeled that are observed in residential HVAC ducts. Reynolds numbers are varied to simulate a variety of flow conditions. The computer code was used to produce pressure drop data along the deformation of the duct. Pressure loss coefficients for the deformed and non deformed duct runs were calculated from the predicted pressure drop data. The results showed that there was a decrease in the pressure loss coefficient as the Reynolds number increased. Also there was a increase in pressure drop coefficients for deformed ducts over the non deformed ducts for the same Reynolds number. The pressure loss coefficient also decreased when the amount of flow in the branch as a percentage of inlet flow was altered to increase. A correlation as a function of Reynolds number and the percentage of air flow is introduced to obtain the pressure loss coefficients in a wye fitting.

Keywords

Air; Analysis; CFD; Deformed; Ducts; HVAC; Leakage; Local; Measurement; Residential

Controlled Subject

Mechanical engineering

File Format

pdf

File Size

1945.6 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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