Thermal Considerations 01/17/2008 Lecture 4 1 Winter 2012 UCSD: Physics 121; 2012 2 Winter 2012 UCSD: Physics 121; 2012 3 Winter 2012 UCSD: Physics 121; 2012 4 Material κ (W m-1 K-1) comments Silver 422 room T metals feel cold Copper 391 great for pulling away heat Gold 295 Aluminum 205 Stainless Steel 10–25 why cookware uses S.S. Glass, Concrete,Wood 0.5–3 buildings Many Plastics ~0.4 room T plastics feel warm G-10 fiberglass 0.29 strongest insulator choice Stagnant Air 0.024 but usually moving… Styrofoam 0.01–0.03 can be better than air!Thermal Considerations 01/17/2008 Lecture 4 2 Winter 2012 UCSD: Physics 121; 2012 5 Winter 2012 UCSD: Physics 121; 2012 6 Winter 2012 UCSD: Physics 121; 2012 7 Winter 2012 UCSD: Physics 121; 2012 8 • Note that these examples use the non-SI definition and are per inch. Vacuum insulated panel has the highest R-value of (approximately 45 in English units) for flat, Aerogel has the next highest R-value 10, followed by isocyanurate and phenolic foam insulations with, 8.3 and 7, respectively. They are followed closely by polyurethane and polystyrene insulation at roughly R–6 and R–5. Loose cellulose, fiberglass both blown and in batts, and rock wool both blown and in batts all possess an R-value of roughly 3. Straw bales perform at about R–1.45. Snow is roughly R–1. • Absolutely still air has an R-value of about 5 but this has little practical use: Spaces of one centimeter or greater will allow air to circulate, convecting heat and greatly reducing the insulating value to roughly R–1Thermal Considerations 01/17/2008 Lecture 4 3 Winter 2012 UCSD: Physics 121; 2012 9 Winter 2012 UCSD: Physics 121; 2012 10 Winter 2012 UCSD: Physics 121; 2012 11 Winter 2012 UCSD: Physics 121; 2012 12Thermal Considerations 01/17/2008 Lecture 4 4 Winter 2012 UCSD: Physics 121; 2012 13 Winter 2012 UCSD: Physics 121; 2012 14 Winter 2012 UCSD: Physics 121; 2012 15 Winter 2012 UCSD: Physics 121; 2012 16Thermal Considerations 01/17/2008 Lecture 4 5 Winter 2012 UCSD: Physics 121; 2012 17 Winter 2012 UCSD: Physics 121; 2012 18 Winter 2012 UCSD: Physics 121; 2012 19 Winter 2012 UCSD: Physics 121; 2012 20Thermal Considerations 01/17/2008 Lecture 4 6 Winter 2012 UCSD: Physics 121; 2012 21 Winter 2012 UCSD: Physics 121; 2012 22 Winter 2012 UCSD: Physics 121; 2012 23 Winter 2012 UCSD: Physics 121; 2012 24Thermal Considerations 01/17/2008 Lecture 4 7 Winter 2012 UCSD: Physics 121; 2012 25 Winter 2012 UCSD: Physics 121; 2012 26 Winter 2012 UCSD: Physics 121; 2012 27 Winter 2012 UCSD: Physics 121; 2012 28Thermal Considerations 01/17/2008 Lecture 4 8 Winter 2012 UCSD: Physics 121; 2012 29 Winter 2012 UCSD: Physics 121; 2012 30 Winter 2012 UCSD: Physics 121; 2012 31 Winter 2012 UCSD: Physics 121; 2012 32Thermal Considerations 01/17/2008 Lecture 4 9 Winter 2012 UCSD: Physics 121; 2012 33 Winter 2012 UCSD: Physics 121; 2012 34 Winter 2012 UCSD: Physics 121; 2012 35 Winter 2012 UCSD: Physics 121; 2012