34. (SI units) A bridge to be fabricated of steel girders is designed to be 800 m long and 20 m wide at ambient temperature (assumed 20°C). Expansion joints will be provided to compensate for the change in length in the girders as the temperature varies Each expansion joint can compensate for a maximum of 25 mm of change in length. From historical records it is estimated that the minimum and maximum temperatures in the region will be -30°C and 45°C, respectively. Determine (a) the minimum number of expansion joints required. Use Table 4.1 from the book for reference. Round to the nearest whole number of joints. Table 4.1 Volumetric properties in U.S. customary units for selected engineering materials Coefficient of Thermal Melting Point, T Density, p Expansion, a Material Cx 10CF 10 g/em (Ib/in) C CF) Metals Aluminum (13.3) (9.4) 2.70 (1220) (0.098) 24 660 Copper 8.97 1083 (0.324) 17 (1981) Iron 7.87 (0.284) (2802) 12.1 (6.7) 1539 Lead 11.35 (0.410) 29 (16.1) (621) 327 Magnesium 1.74 (0.063) 26 (1202) (14.4) 650 Nickel 8.92 (0.322) 13.3 (7.4) 1455 (2651) Steel 7.87 (0.284) 12 (6.7) (12.7) a a Tin 7.31 (0.264) 23 232 (449) Titanium 4.51 (0.163) 8.6 (4.7) 1668 (3034) Tungsten 19.30 (0.697) 4.0 (2.2) 3410 (6170) Zinc 7.15 (0.258) 40 (22.2) 420 (787) Ceramics and Silicon Glass 2.5 (0.090) 1.8-9.0 (1.0-5.0) Alumina 3.8 (0.137) 9.0 (5.0) 2072 (3762) Silica 2.66 (0.096) 0.55 (0.31) 1600 (2912) Silicon 2.33 (0.085) 2.6 (14) 1414 (2577) Polymers Phenol resins 1.3 (0.047) 60 (33) Nylon 1.16 (0.042) 100 (55) 260 (500) Polyethylene 0.92 (0.033) 180 (100) 115 (240) Polystyrene Polyvinylchloride 1.05 (0.038) 70 (39) (464 240 1.40 (0.051) 50 (28) 212 (414) Compiled from, 121. 131. 14). I5], and other sources Melting temperature depends on composition. Low-density polyethylene Chemically degrades at high temperatures because it is a thermosetting polymer, other polymers listed are thermoplastic

Problem 1. (Taken from Bergman et.al. 2011*) An igloo is built in the shape of a hemisphere, with an inner radius of 1.8 m and walls of compacted snow that are 0.5 m thick. On the inside of the igloo the surface heat transfer coefficient is 6 W/m².K; on the outside, under normal wind conditions, it is 15 W/m².K. The thermal conductivity of compacted snow is 0.15 W/m.K. The temperature of the ice cap on which the igloo sits is -20 °C and has the same thermal conductivity as the compacted snow. Artic wind Too Tair Ice cap Tice Igloo Assuming that the occupants' body heat provides a continuous source of 320 W within the igloo, calculate the inside air temperature when the outside air temperature is T∞ = -40 °C draw a thermal circuit for the heat transfer from the igloo. Be sure to consider heat losses through the floor of igloo where the heat transfer coefficient is 6 W/m²K.

Qigihar House in Heilongiiang Province, China Heat Loss Problems, BSCl 2101 Climate: Avg. remperature is 3.2°C Degree Days is 5000 Inside Air Temp. is 20°C Wall Construction, Inside to Out: 15mm Gypsum Plaster, Sand Aggregate Concrete Block, rectangular core, Sand and Gravi 15mm Cement Plaster, Sand Aggregate All 4 walls measure the same, 8m wide by 7mtall. The house is heated with electricity at a cost of $0.10kWh Calculate the RSI-total for the walls using the tabular method demonstrated in class, and the temperature drop through each element for the January 2.5% temperature. Calculate the rate of heat flow through the wall again for the January 2.5% temperature. Plot the temperature profile approximately to scale through a vertical cross-section of the wall. Calculate the January heating cost for the building. Calculate the annual heating cost for the building. Now add 2" ( 50.8mm ) of extruded polystyrene, smooth skin surface, 35kgm3 rigid insulation to the inside surfaces…

M4.18 (Sl units) A bridge to be fabricated of steel girders is designed to be 500 m long and 12 m wide at ambient temperature (assumed 20°C). Expansion joints will be provided to compensate for the change in length in the girders as the temperature varies. Each expansion joint can compensate for a maximum of 20 mm of change in length. From historical records it is estimated that the minimum and maximum temperatures in the region wll be-35°C and 40°C, respectively. Determine (a) the minimum number of expansion joints required. Use Table 4.1from the book for reference. Round to the nearest whole number of joints.