0.20.l 12:42景令60...KB/slaung mateilais, (C) nquius, (u) gases:9. Suppose a person stated that heat cannot be transferred in a vacuum. How do yourespond?10. Review any standard text on thermodynamics and define: (a) heat, (b) internal energy,(c) work, (d) enthalpy.11. Define and discuss ge.LIST OF WORKED EXAMPLES1-1 Conduction through copper plate1-2 Convection calculation1-3 Multimode heat transfer1-4 Heat source and convection1-5 Radiation heat transfer1-6 Total heat loss by convection and radiationPROBLEMS1-1 If 3 kW is conducted through a section of insulating material 0.6 m2 in cross sectionand 2.5 cm thick and the thermal conductivity may be taken as 0.2 W/m - °C, computethe temperature difference across the material.1-2 A temperature difference of 85°C is impressed across a fiberglass layer of 13 cmthickness. The thermal conductivity of the fiberglass is 0.035 W/m - °C. Compute theheat transferred through the material per hour per unit area.1-3 A truncated cone 30 cm high is constructed of aluminum. The diameter at the top is7.5 cm, and the diameterat 93°C; the upper surface, at 540°C. The other surface is insulated. Assuming one-t the bottom is 12.5 cm. The lower surface is maintaineddimensional heat flow, what is the rate of heat transfer in watts?he temperatures on the faces of a plane wall 15 cm thick are 375 and 85°C. The wallis constructed of a special glass with the following properties: k=0.78 W/m - °C,p=2700 kg/m³, cp=0.84 kJ/kg - °C. What is the heat flow through the wall atsteady-state conditions?1-5 Acertain superinsulation material having a thermal conductivity of 2 x 10-4 W/m - °Cis used to insulate a tankliquid nitrogen that is maintained at –196°C; 199 kJ isrequired to vaporize each kilogram mass of nitrogen at this temperature. Assumingthat the tank is a sphere having an inner diameter (ID) of 0.52 m, estimate the amountof nitrogen vaporized per day for an insulation thickness of 2.5 cm and an ambienttemperatureof 21°C. Assume that the outer temperature of the insulation is 21°C.1-6 Rank the following materials in order of (a) transient response and (b) steady-stateconduction. Taking the material with the highest rank, give the other materials asa percentage of the maximum: aluminum, copper, silver, iron, lead, chrome steel(18% Cr, 8% Ni), magnesium. What do you conclude from this ranking?1-7 A 50-cm-diameter pipeline in the Arctic carries hot oil at 30°C and is exposed to asurrounding temperature of -20°C. A special powder insulation 5 cm thick surroundsProblemsthe pipe and has a thermal conductivity of 7 mW/m - °C. The convection heat-transcoefficient on the outside of the pipe is 9 W/m² . °C. Estimate the energy loss frthe pipe per me1-8 Some people nigh46 of 758 out the top of yourweather becausvalidity of this statement.1-9 A 5-cm layer of loosely packed asbestos is placed between200°C. Calculate the heat transfer across the layer.of length.be sure to put on ale in et onat 1001-10 A certain insulation has a thermal conductivity of 10 W/m . °C What thicknes||II

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1-1 If 3 kW is conducted through a section of insulating material 0.6 m2 in cross section and 2.5 cm thick and the thermal conductivity may be taken as 0.2 W/m - °C, compute the temperature difference across the material.