ORCID Identifier(s)

0000-0002-7211-5523

Graduation Semester and Year

2019

Language

English

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Dereje Agonafer

Abstract

Air side economization is an arrangement of duct, damper and automatic control system which together allow introducing outside air to reduce the mechanical cooling during mild or cold weather thereby decrease the energy consumption. The outside ambient air and heated return air from the information technology (IT) pod is mixed inside a dedicated space to achieve a target cold aisle operating temperature and thereby increase economization. Major constrain faced by the design engineers while designing the Mixing Chamber/ Plenum is the stratification of air stream due to the Temperature gradient in the mixed air stream and this stratification can be attributed to the short span of time and space that is available for the air streams to interact with each other. Thermal stratification can lead to coil freeze-ups, nuisance freeze-stat trips, energy wastage due to sensing error and poor indoor air quality and increases the cooling power. So, to achieve our objective we want to understand the fundamental physical phenomenon which causes mixing of any two fluids and thereby apply the knowledge to our test scenario. Literature review gave us the information about Richardson number a dimensionless number which is a ratio between buoyancy and flow shear stress and for improving the process of mixing the Richardson number should be minimized. The variables involved in minimizing the Richardson number are the velocity and temperature difference between the two fluid and the total vertical column height of the two fluid that needs to be mixed. This fundamental understanding will help us in determining the structural features needs to be achieve the desired mixing. The scope of the project is also extended to address the effect of thermal stratification after evaporative media cooling pad, in this scenario the process of segmentation of the pad for reducing the relative humidity also creates thermal stratification. Computational Fluid Dynamic analysis is carried out to report the proof of concept and thereby report the changes in the effectiveness of the mixing process at upstream of heating coil and downstream of cooling pad.

Keywords

Data center, Thermal stratification, Air cooled data center, CFD, Air handlers

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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