Concept explainers
The composite insulation shown, which was described in Chapter 1 (Problem 1.86e), is being considered as a ceiling material.
It is proposed that the outer and inner slabs be made from low-density particle board of thicknesses
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Fundamentals of Heat and Mass Transfer
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DESIGN OF MACHINERY
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
- Thank you for you assistarrow_forwardYou are asked to design an insulated stud timber wall and have the following materials available: Outer skin materials. ● Plasterboard 8 mm thick (k= 0.3 W/m.K) Plasterboard 12.5 mm thick (k = 0.3 W/m.K) Insulated Plasterboard 25 mm thick (k = 0.2 W/m.K) Timber studs available (k = 0.1 W/m.K) 50 mm x 100 mm 50 mm x 120 mm 50 mm x 150 mm Insulation layers Glass fibre insulation (k= 0.05 W/m.K) ● Polyisocyanurate insulation (k= 0.025 W/m.K) Sheeps wool insulation (k= 0.04 W/m.K) ● Wall construction should consist of two outer plasterboard skins, followed by an appropriate stud/insulation infill layer. Studs can be placed vertically at 400 mm or 600 mm intervals and you may ignore any requirement for horizontal studding. 1) Draw a plan (top view) cross section of your wall indicating dimensions, spacing and material choices. 2) Calculate the thermal resistance of your wall. 3) If the internal convective heat transfer coefficient in room one is 10 W/m²K and in the second room it is 15…arrow_forward1. An element of graphite-reinforced composite is completely dry and is constrained against any dimensional changes in the 1 and 2 directions, but it is free to expand in the 3 direction. The element absorbs 1.5% of its dry weight in the form of moisture. (a) What is the strain in the 3 direction as a result of the moisture absorption? Why is this strain different from the value given by B3AM? (b) What stresses develop in the element? Assume that moisture absorption does not influence the material properties.arrow_forward
- An eyed plate & pin is assembled as illustrated and are subjected to an opposing force of 10KN. The rod diameter & plate thickness is 6mm. The width of the plate is 20mm. A hole to which the pin is inserted is 8mm in diameter is located at the center of the plate. The plate is made of annealed SAE 1025 & the pin is high-heat oil quenched SAE 1095. (a) Determine if the assembly is safe to use; otherwise (b) Determine the safe load of the assembly.arrow_forwardA cold storage room has a wall consists of an inside finish of 0.60 in cement plaster(k = 0.67), two layers of corkboard each 2.5 in thick (k = 0.03) and an outside layer of building tile. The value of U for the entire wall is 0.058, the internal air filmcoefficient is 1.65, the inner temperature is 23°F and the outside temperature is85°F. Calculate the heat flow through the unit wall area, Btu/hr.ft2A. 1.47 B. 2.47 C. 3.47 D. 4.47arrow_forwardA continuous and aligned fibrous reinforced composite having a cross-sectional area of 975 mm, then the area is subjectedi to an extenal tensile load. If the stresses sustained by the fibre and matrix phases are 215 MPa and 5.38 MPa, respectively, the force sustained by the fibre phase is 76,800 N, and the total longitudinal composite strain is 1.56x103 then determine.arrow_forward
- Suppose a steel strut having a cross-sectional area of 7.00 x 10-4 m2 and length 2.20 m is bolted between two rigid bulkheads in the engine room of a submarine. Assume the density of steel is the same as that of iron (7.86 x 103 kg/m3). (a) Calculate the change in temperature of the strut if it absorbs an energy of 3.00 x 105 J of thermal energy. (b) Calculate the compressional stress in the strut.arrow_forward1.A composite component is comprised of a tube and a concentric rod running inside it, both with a length of 1.5 meters. The tube is made of copper and has inner and outer diameters of 60 mm and 100 mm, respectively, a coefficient of thermal expansion and elastic modulus of 17 ×10−6? and 117 GPa, respectively. The rod is made of aluminium with a diameter, coefficient of thermal expansion and elastic modulus of 50 mm, 23 ×10−6? and 80 GPa, respectively. If the composite is exposed to a temperature rise of 120°C, determine:1.1 The sense and magnitude of the stresses induced in the composite if it is not restrained. 1.2 The sense and magnitude of the stresses induced in the composite if it is partially restrainedwith an allowed free expansion of 0.3 mm.arrow_forwardA leading manufacturer of household appliances is proposing a self-cleaning oven design that involves use of a composite window separating the oven cavity from the room air (Figure 2a). The composite is to consist of two high-temperature plastics (A and B) of thicknesses LA = 2LB and thermal conductivities ka = 0.15 W/m K and KB = 0.08 W/m K. During the self-cleaning process, the oven wall and air temperatures, Tw and Ta, are 400°C, while the room air temperature To is 25°C. The inside convection and radiation heat transfer coefficients h; and hr, as well as the 2 a) outside convection coefficient ho, are each approximately 25 W/m².K. What is the minimum window thickness, L = LA + LB, needed to ensure a temperature that is 50°C or less at the outer surface of the window? This temperature must not be exceeded for safety reasons.arrow_forward
- The compressive strength of aramid fiber is about one-eighth of its tensile stress. Estimate the smallest diameter of a rod on which the aramid fiber can be wound without causing kinks, etc., on its compression side.arrow_forwardTo 8. 22 1 2 T₁ 3 1. 2. 3. 4" Common Brick 1/2" OSB Sheathing 3-1/2" x 1-1/2" (2x4) Yellow Pine Studding placed on 16" center 4. 5. 3-1/2" Figerglass Insulation 1/2" Drywall A wall of a house as shown in the accompanying sketch is 10 ft. high and 30 ft. long and has no windows. The outside heat transfer coefficient, h., is 6.0 Btu/hr ft2°F and the inside convective heat transfer coefficient hi is 1.45 Btu/hr ft²°F. 6. Calculate the heat loss through the wall if the house is heated such that the room air temperature, Ti, is 70°F on a day when the outside air temperature, T., is 0°F. State all assumptions and list the thermal resistances and thermal conductivities for each selection of the wall. For this problem, what would be the 7. value of the overall heat transfer coefficient, U? Ans: U = 0.056 Btu/hr ft2°F You are asked to design a metal hot dog holder for roasting hot dogs over an open campfire. The holder is to be designed such that while the end holding the hot dog becomes cherry…arrow_forwardPlease include free body diagram and please don't typearrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning