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Wind Chill Effect & Thermal Insulation

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Wind Chill Effect & Thermal Insulation Faculty of Natural Sciences and Technology Wind Chill Effect & Thermal Insulation Study of Wind Chill Effect and Thermal Insulation using Infrared Imaging Tanveer Ahmad Master in Technology and Safety in High North, May 2017 Preface This report is submitted in the course TEK-3901 (Master thesis – 30 stp) that is part of the Masters in Technology and Safety at UiT The Arctic University of Norway, Tromsø, Norway. The work described in this report was carried out at the Department of Engineering and Safety in 2016-17. It is the original and independent work of author except where specially acknowledged in the text. Neither the present report nor any part thereof has been previously submitted at any other university. This report contains approximately 11445 words, 35 figures, and 10 tables. Tanveer Ahmad Department of Engineering and Safety UiT – The Arctic University of Norway May 2017 i Acknowledgement I would like to acknowledge the support of Mr. Taimur Rashid, Mr. Intisab Alam Khan and Dr. Hassan A. Khawaja at Department of Engineering and Safety, UiT-The Arctic University of Norway. Tromsø, May 15, 2017 Tanveer Ahmad ii Abstract Wind chill factor is explained as the cooling sensation due to the exposure of wind temperature environment. The wind chill factor depends on air temperature, wind velocity, and humidity. Wind chill poses serious health risks. Various wind chill index models are given in the literature. In order to understand the wind chill effect, it is important to understand the phenomenon of heat transfer. There are three modes of heat transfer namely conduction, convection and radiation. The convective mode of heat transfer is most dominant in the case of wind chill. BS-EN 342 and ISO 11079:2007 (E) defines the clothing insulation requirements. Preliminary experiments using infrared thermography in cold room at The Arctic University of Norway demonstrates higher heat transfer under wind chill conditions with the means of infrared imaging. The experiments were also conducted to measure the relative required insulation of winter jackets, summer jackets and sweaters via infrared imaging. iii “The sun was warm but the wind was chill. You know how it is with an April day. When the sun is out and the wind is still, You're one month on in the middle of May. But if you so much as dare to speak, a cloud come over the sunlit arch, And wind comes off a frozen peak, And you're two months back in the middle of March.” Robert Frost iv Contents Preface ......................................................................................................................... i Acknowledgement ....................................................................................................... ii Abstract ...................................................................................................................... iii List of Figures ............................................................................................................ vii List of Tables .............................................................................................................. ix Nomenclature .............................................................................................................. x Chapter 1. Introduction ........................................................................................ 13 1.1 Wind Chill Factor ......................................................................................... 13 1.2 Objective of Report ...................................................................................... 15 1.3 Effects of Cold Weather on Human Body .................................................... 15 1.4 Metrological Perspective of Wind Chill Factor ............................................. 17 1.5 Protective Clothing – Thermal Insulation in Cold Environment .................... 19 1.6 Structure of the Report ................................................................................ 20 Chapter 2. Literature Review ............................................................................... 21 2.1 Review of Wind Chill Factor Models ............................................................ 21 2.1.1 Siple and Passel’s Wind Chill Experiment ............................................ 21 2.1.2 Osczevski Wind Chill Model .................................................................. 22 2.1.3 New Wind Chill Equivalent Temperature Chart ..................................... 25 2.2 Risk Associated with Wind Chill Factor ....................................................... 26 2.3 Protective Clothing ...................................................................................... 28 2.3.1 British Standard-EN 342 [21] ................................................................ 29 2.3.2 ISO 11079:2007 (E) [22] ....................................................................... 32 2.4 Review of the Phenomenon of Heat Transfer .............................................. 36 2.4.1 First Mode of Heat Transfer: Conduction .............................................. 36 2.4.2 Second Mode of Heat Transfer: Convection ......................................... 38 2.4.3 Third Mode of Heat Transfer: Radiation ................................................ 41 Chapter 3. Methodology ...................................................................................... 42 3.1 Infrared Imaging .......................................................................................... 42 3.1.1 Infrared Camera .................................................................................... 44 3.1.2 Image Analysis ...................................................................................... 51 3.2 Cold Room .................................................................................................. 53 3.3 Protective Clothing ...................................................................................... 56 Chapter 4. Results and Discussion ..................................................................... 60 4.1 Wind Chill Study using IR Imagery .............................................................. 60 4.2 IREQ Study using IR Imagery ..................................................................... 66 v Chapter 5. Conclusions and Future Work ........................................................... 72 5.1 Conclusions ................................................................................................. 72 5.2 Future Work ................................................................................................. 74 References ............................................................................................................... 75 Appendix - A ............................................................................................................. 78 Appendix - B ............................................................................................................. 82 vi List of Figures Figure 1.1: Wind draws heat from human body creating the wind chill factor. .......... 14 Figure 1.2: Effective / Feel like Temperature with respect to Actual Temperature (In Norwegian: Lufttemperatur) and Wind Velocity (In Norwegian: Vindstyrke). All given temperature values are in degree centigrade [20]. ................................................... 18 Figure 2.1: Wind Chill Index (kCal/m2) with Wind Speed (m/s) for various facial temperatures ranging from -5°C to 20°C [26]. .......................................................... 24 Figure 2.2: Wind Chill Temperature (°C) with Air Temperature (°C) and Wind Speed (km/h). Shaded region shows when frostbite may occur. ......................................... 25 Figure 2.3: Categorization of Wind Chill Index [29] ................................................... 26 Figure 2.4: Exposure Risk, Health Concerns and What to Do under various Wind Chill conditions [29]. ................................................................................................. 27 Figure 2.5: Procedure for evaluation of cold environments. ..................................... 33 Figure 2.6: Heat transfer through conduction (a) Linear heat transfer (or constant heat flux) (b) Nonlinear heat transfer (or variable heat flux) ..................................... 37 Figure 2.7: Heat transfer through a wall. Wall is warmed by hot fluid on one side and cooled by cold fluid on other. A steady state temperature gradient exists within the solid wall. .................................................................................................................. 39 Figure 2.8: A surface emitting thermal radiations [31]. ............................................. 41 Figure 3.1: Electromagnetic Spectrum [34]............................................................... 43 Figure 3.2: Infrared Spectrum [35]. ........................................................................... 44 Figure 3.3: False Coloured Infrared Image (a) taken with Fluke® Ti55 IR camera; (b) taken with Flir® T1030sc IR camera. ........................................................................ 45 Figure 3.4: Working Principle of an IR Camera ........................................................ 46 Figure 3.5: Fluke® Ti55 IR Camera .......................................................................... 46 Figure 3.6: Flir® T1030sc Camera ........................................................................... 47 Figure 3.7: Focal plane Array model. .......................................................................
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