MODELLING PHASE CHANGE MATERIAL THERMAL STORAGE SYSTEMS
MODELLING PHASE CHANGE MATERIAL THERMAL STORAGE SYSTEMS
By
JOANNE M. BAILEY, B.A.Sc., P .Eng.
A Thesis
Submitted to the School of Graduate Studies
in Partial Fulfillment of the Requirements
for the Degree
Master of Applied Science
McMaster University
Hamilton, Ontario, Canada
Copyright by Joanne Bailey, January 2010
MASTER OF APPLIED SCIENCE (2010) (Mechanical Engineering)
McMASTER UNNERSITY Hamilton, Ontario, Canada
TITLE: Modelling Phase Change Material Thennal Storage Systems
AUTHOR: Joanne M. Bailey, B.A.Sc., P. Eng.
SUPERVISOR: Dr. J. S. Cotton
NUMBER OF PAGES: xiv, 157
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ABSTRACT
In order to increase the overall efficiency of energy use in a community, excess
thermal energy from inefficient processes can be stored and used for heating applications.
A one-dimensional analytical conduction model is therefore developed for sizing of phase
change material thermal energy storage systems. The model addresses rectangular
channels of phase change material separated by flow channels for the addition and
removal of thermal energy. The analytical model assumes a planar melt front and linear
temperature profiles throughout the thermal storage cell. Heat flux and interface
temperatures are calculated at various melt fractions based on a quasi-steady electrical
analogue analysis of the instant in question. Compensation is made for the sensible
energy change between melt fractions by adding this energy at the calculated heat flux.
A two dimensional, conduction only computational fluid dynamics model is used to
compare the response of the analytical model to changes in the input parameters and
shows good agreement. A test apparatus and a three dimensional computational fluid
dynamics model are also created and melt-time results compared to analytical model
predictions. These comparisons also show good agreement. Finally, a thermal storage
system is sized for a specific application, H2Green Energy Corporation's Distributed
Storage System, with sizing based on the heat load requirements of McMaster Innovation
Park during the winter months. Technical feasibility of this system is shown with
analysis also included on economic feasibility. It is determined that the analytical model
is sufficient for initial assessment of phase change material thermal energy storage
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systems where detailed geometry is unavailable. Recommendations are made for further
validation of the model and the development of a phase change material properties
database. Suggestions are also presented on additional sources of revenue for the
H2Green Distributed Storage System that will increase its economic feasibility.
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ACKNOWLEDGEMENTS
The author would like to acknowledge the financial contributions of the Ontario
Centres of Excellence, H2Green Energy Corporation, McMaster University Department
of Mechanical Engineering, NSERC and the Canadian Engineering Memorial Foundation
towards completion of this thesis.
The author would also like to thank Dan Wright for his assistance with data
acquisition and programming, Ron Lodewyks, J.P. Talon, Mark MacKenzie, Jim
McLaren and Joe Verhaeghe for their help with the fabrication of the experimental
apparatus, Dr. J.S. Cotton for his guidance and supervision over the course ofthis project
and Dr. H.S. Sadek for his continual support and advice.
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Table of Contents
Abstract .............................................................................................................................. iii
Acknowledgements ............................................................................................................. v
List of Tables ..................................................................................................................... ix
List of Figures ..................................................................................................................... x
Nomenclature .................................................................................................................... xii
Glossary ........................................................................................................................... xiii
CHAPTER 1 - Introduction ................................................................................................... 1
1.1 - Background ............................................................................................................ 1 1.2 - Current Applications of Thermal Storage ................................................... , .......... 2 1.3 - Potential Applications of Thermal Storage ............................................................ 5 1.4 - Problem .................................................................................................................. 7 1.5 - Scope of Work ....................................................................................................... 8
CHAPTER 2 - Thermal Storage Technologies ................................................................... 10
2.1 - Thermal Storage Options ..................................................................................... 10 2.2 - Phase Change Material Categories ...................................................................... 12 2.3 - Low Temperature Phase Change Materials ......................................................... 13 2.4 - Recent Phase Change Material Thermal Storage Research ................................. 19 2.5 - Capture Systems ................................................................................................... 24 2.6 - Recovery Systems ................................................................................................ 26 2.7 - Temperature Mediation Systems ......................................................................... 27 2.8 - Design Methodology ............................................................................................ 27
CHAPTER 3 ~ PCM Thermal Storage Models .................................................................... 32
3.1 - PCM Mass ............................................................................................................ 32 3.2 - One-Dimensional Storage Cell Geometric Model ............................................... 33 3.3 - Analytical Model Single Storage Cell Time ........................................................ 34
3.3.1 - Pseudo-Steady Heat Transfer Model ............................................................ 35 3.3.2 - Changing Temperature Profile and Sensible Energy .................................... 36 3.3.3 - Equations Used in the Analytical Model ...................................................... 37
3.4 - Fluent Melting/Solidification Model ................................................................... 38 3.5 - Two-Dimensional Numerical Storage Cell Model .............................................. 39
VI
3.5.1- Effect ofTheffilal Conductivity .................................................................... 44 3.5.2 - Effect of Latent Heat of Fusion ..................................................................... 49 3.5.3 - Effect of Sensible Energy Storage ................................................................ 50 3.5.4 - Effect of Capture/Recovery Temperature Difference ................................... 52 3.5.5 - Effect of Dimensional Changes .................................................................... 54 3.5.6 - Effect of Capture/Recovery Convective Heat Transfer Coefficient ............. 55
3.6 - Three-Dimensional Sample Cell Model .............................................................. 56 3.6.1 - Lauric Acid Storage Cell ............................................................................... 57
CHAPTER 4 - Test Facility ................................................................................................. 62
4.1 - Test Cell Design Criteria and Constraints ............................................................ 62 4.2 - Phase Change Material Chamber ......................................................................... 65 4.3 - Capture/Recovery Fluid ChanneL ........................................................................ 68 4.4 - Temperature Measurement .................................................................................. 73 4.5 - Flow Measurement and Control. .......................................................................... 75 4.6 - Heat Flux Measurement ....................................................................................... 76 4.7 - Data Acquisition .................................................................................................. 77 4.8 - Experimental Uncertainty .................................................................................... 79
CHAPTER 5 - Experimental Results, Discussion and Comparison .................................... 82
5.1 - Experimental Phase Change Results and Model Validation ................................ 82 5.2 - Lauric Acid Storage Cell Low Flow .................................................................... 83 5.3 - Effect of Flow Rate .............................................................................................. 89 5.4 - Effect of Flow Direction .......................................................................
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