ABSTRACT ROSS, KELLY ANN. Energy Flow in Multilayer Clothing Systems. (Under the direction of Trevor J. Little). Clothing has a large part to play in the maintaining the body’s heat balance especially during exercise. This research investigated how to build a layered clothing system that would optimize moisture management and performance during athletic end use. During physical activity muscles burn nutrients which releases energy in the form of heat. The human should maintain a constant core temperature of about 37 degrees Celsius, from which only a small change (+/-) ~4°C can lead to serious injury or death. There are four mechanisms that allow the body to lose heat to the environment in order to maintain its thermal balance: conduction, convection, radiation, and evaporation. This research utilizes a test method where multiple fabric layers are tested simultaneously as a person would wear multiple garment layers together. Typical existing testing procedures for the measure of heat and moisture transport in textile materials are successful in measuring one layer of fabric at a time. However, people typically wear more than one layer of clothing especially on their upper torso which could include a foundation garment such as a sports bra, undershirt or t-shirt, and an additional layer consisting of a shirt or jacket. As part of this research, a fabric testing kit was designed in order to test three different fabric layers at the same time while mounted on a human subject during exercise. This fabric testing kit measured coupled heat and moisture transfer in relation to temperature and humidity across the microclimates, the interaction between clothing to skin, and the layer to layer interactions of a clothing system. Human subjects who participated in this research were athletic and capable of riding a stationary bicycle for an extended period of time in order to produce perspiration. Both males and females participated in this study. A total of eleven different subjects were used in this research including seven males and four females. Ten different fabrics were chosen to be evaluated by the fabric testing kit. Knowledge gained through this research can be used to design better clothing systems more suited to satisfy the needs of athletes or regular exercisers, especially those who will be perspiring for a longer time such as long distance runners and cyclists. Also, this research provides an in depth analysis of an athletes’ warm up prior to training or competing, which can aid in the development of clothing systems that effectively warm muscles to a competing temperature and prevent formation of lactic acid build up before or after the competition. © Copyright 2013 Kelly Ann Ross All Rights Reserved Energy Flow in Multilayer Clothing Systems by Kelly Ann Ross A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Textile Technology Management Raleigh, North Carolina 2013 APPROVED BY: _______________________________ _______________________________ Trevor J. Little Roger L. Barker Committee Chair _______________________________ _______________________________ Katherine E. Carroll Hechmi Hamouda DEDICATION To my mother, a wonderful woman full of strength and light. The memory of her light will always burn bright in my heart. She was an inspiration of hope and faith to all that knew her. "Do not grieve, for the joy of the LORD is your strength," Nehemiah 8:10. ii BIOGRAPHY Kelly Ann Ross was born September 1, 1979 to Steve and Ann Goforth in Shelby, North Carolina. She spent most of her youth living with her parents and two brothers, Jamie and John in Cleveland County right outside of Kings Mountain, North Carolina. She attended Bethware Elementary School and Kings Mountain Middle School before graduating from Kings Mountain High School in 1997. In May of 2005, she graduated with a Bachelor’s of Science in Textile Management from North Carolina State University. In the fall of 2005, Kelly continued her education at NCSU pursuing a Master’s of Science in Textiles. She was fortunate to be selected as an Institute of Textile Technology Graduate Fellow for the Class of 2007. On November 11, 2006, she married Kevin Andrew Ross, alumni and employee of North Carolina State University. Kelly graduated with a Master of Science on May 12, 2007. After graduation, Kelly began working at Glen Raven, a vertically integrated textile company located near Burlington, NC. In the fall of 2009, Kelly returned to NCSU as a graduate teaching assistant and received a Certificate of Accomplishment in Teaching in April 2011; she will graduate with her doctorate in December 2013. Her daughter Katharine Anslee Ross was born June 12, 2010. Kelly’s most influential role model is her mother, a retired chemistry educator who lost her battle against cancer in April 2013. iii ACKNOWLEDGMENTS I would like to express my most sincere gratitude to my research advisor, Trevor J. Little for his advice, guidance, and support throughout my research. I would also like to thank the other members of my committee and former professors who are all special to me in their own unique ways. I am also grateful to my fellow graduate students and classmates for their encouragement and friendship. I am also grateful to my family and my church. I owe a great deal of gratitude to the NC State Cycling Club as well as the coaches and staff at Weisiger- Brown Athletics Facility. I will always appreciate their help in making this research possible. iv TABLE OF CONTENTS LIST OF TABLES .................................................................................................................. xi LIST OF FIGURES ............................................................................................................... xii 1. Introduction ...................................................................................................................... 1 2. Literature Review ............................................................................................................. 4 2.1. Theoretical Models for Human Comfort ............................................................... 5 2.1.1. Fourt and Hollies' Comfort Triad (1970) ....................................................... 5 2.1.2. Pontrelli's Comfort Gestalt (1977) ................................................................. 6 2.1.3. Sontag's Comfort Triad (1985) ....................................................................... 7 2.1.4. Branson and Sweeney's Clothing Comfort Model (1991) ............................. 8 2.2. Physiological Aspect of Comfort ........................................................................ 11 2.2.1. Heat Balance ................................................................................................ 12 2.2.2. Environmental Thermal Conditions ............................................................. 12 2.2.3. Metabolic Rate ............................................................................................. 14 2.2.4. Conduction ................................................................................................... 17 2.2.5. Convection ................................................................................................... 18 2.2.6. Radiation ...................................................................................................... 18 2.2.7. Evaporation .................................................................................................. 19 2.2.8. Thermal and Moisture Management of Clothing ......................................... 20 v 2.3. Theoretical Background of Heat Transport ......................................................... 21 2.3.1. Thermodynamics .......................................................................................... 21 2.3.2. The Microclimate ......................................................................................... 24 2.4. Newton’s Law of Cooling ................................................................................... 25 2.5. Fourier’s Law ...................................................................................................... 26 2.6. Heat Transport through Textiles .......................................................................... 27 2.6.1. Insulation ...................................................................................................... 28 2.6.2. Air Permeability ........................................................................................... 29 2.6.3. Stefan-Boltzmann Law ................................................................................. 30 2.7. Theoretical Background of Moisture Transport .................................................. 31 2.7.1. Water Vapor Diffusion ................................................................................. 32 2.7.2. Moisture Sorption-Desorption ..................................................................... 34 2.7.3. Wicking and Wetting ................................................................................... 35 2.7.4. Biomimicry of Moisture Management ......................................................... 36 2.8. Coupled Heat and Moisture Transfer .................................................................. 37 2.8.1. Woodcock..................................................................................................... 37 2.8.2. Clausisus-Clapeyron....................................................................................