Consider Figure 1.3. The heat flux in the x-direction is
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Introduction to Heat Transfer 6th Edition (Wiley Editor's Choice Edition)
- A square silicon chip 7mm7mm in size and 0.5-mm thick is mounted on a plastic substrate as shown in the sketch below. The top surface of the chip is cooled by a synthetic liquid flowing over it. Electronic circuits on the bottom of the chip generate heat at a rate of 5 W that must be transferred through the chip. Estimate the steady-state temperature difference between the front and back surfaces of the chip. The thermal conductivity of silicon is 150 W/m K. Problem 1.6arrow_forward1.3 A furnace wall is to be constructed of brick having standard dimensions of Two kinds of material are available. One has a maximum usable temperature of 1040°C and a thermal conductivity of 1.7 W/(m K), and the other has a maximum temperature limit of 870°C and a thermal conductivity of 0.85 W/(m K). The bricks have the same cost and are laid in any manner, but we wish to design the most economical wall for a furnace with a temperature of 1040°C on the hot side and 200°C on the cold side. If the maximum amount of heat transfer permissible is 950 , determine the most economical arrangement using the available bricks.arrow_forwardWhat is the rate of heat transfer through a piece of Celotex 3 ft by 8 ft by 1 in. in thickness, if the temp of one surface is 80°F and of the other side is 60°F? thermal conductivity of Celotex in AES = 0.028. Pls determine the temperature gradient and the direction of the heat transfer as well.arrow_forward
- A curved surface of a rod of length L is perfectly insulated against the flow of heat . The rod , which is so thin that heat flow in it can be assumed to be one dimensional , is initially at the temperature U(x,0 ) = 20 x / 3L ° C . Find the temperature at any point in the road at any subsequent time if at t = 0 the temperature at each end of the rod is suddenly reduced to 0 ° C and maintained at that temperature thereafter .arrow_forwardQ1 A field investigation of the thermal environment has been conducted for a room with an external wall facing east. The wall are made of 150 mm brick (k = 0.9 W/m°C) and 15 mm of plaster (k= 0.3 W/m°C) on both sides. The results are as shown in Figure Q1(a) and Figure Q1(b), representing the temporal wall surface temperature and indoor air temperature respectively. (i)Based on the graph in Figure Q1(a), analyze the value of the conductive heat flow (Q) for the wall at 11:00 a.m. and 15:00 p.m. and discuss ONE (1) potential cause of the difference. Given the value of external and internal surface resistance are 0.06 m2°C/W and 0.12 m2°C/W, respectively. Meanwhile, the area of the wall is 12m2 . (ii) Based on your reason in Q1(i), propose TWO (2) practicable strategies that can reduce the external wall surface temperature during that time. (iii) As shown in Figure Q1(b), the indoor air temperature of the room reached its peak (maximum temperature) at about 1.5 hours later than that of…arrow_forwardA vertical cylinder 6 ft tall and 1 ft in diameter might be used to approximate a man for heat-transfer purposes. Suppose the surface temperature of the cylinder is 78°F, h=2 Btu/h · ft2 . °F, the surface emissivity is 0.9, and the cylinder is placed in a large room where the air temperature is 68°F and the wall temperature is 45°F. Calculate the heat lost from the cylinder. Repeat for a wall temperature of 80°F. What do you conclude from these calculations? Known, Find, Schematic Diagram, Assumption, Properties, Analysis and Commentsarrow_forward
- A vertical cylinder 6 ft tall and 1 ft in diameter might be used to approximate a man for heat-transfer purposes. Suppose the surface temperature of the cylinder is 78°F, h=2 Btu/h · ft2 . °F, the surface emissivity is 0.9, and the cylinder is placed in a large room where the air temperature is 68°F and the wall temperature is 45°F. Calculate the heat lost from the cylinder. Repeat for a wall temperature of 80°F. What do you conclude from these calculations?arrow_forward(a) What is the rate of heat transfer through a wall that is 2 m high by 2.5 m wide?(b) Sketch the temperature distribution.arrow_forwardA furnace wall is constructed of a firebrick that is 6 inches thick. The temperature of the inside of the wall is 1300°F, and the temperature of the outside of the wall is 175°F. If the mean thermal conductivity under these conditions is 0.17 BTU/hr-ft-°F. What is the rate of heat loss through 10 square feet of wall surface?arrow_forward
- A 100 mm diameter steam pipe is covered by two layers of lagging (insulation). The inside layer is 40 mm thick and has a thermal conductivity of 0.07 W/m K. The outside layer is 25 mm thick and has a thermal conductivity of 0.1 W/mK. The pipe carries steam at a temperature of 234°C , where the outside temperature of lagging is 24°C. If the steam pipe is 20 m long, determine (a) The heat lost per hour, (b) The interface temperature of lagging. Neglect the resistance of steam pipe as well as the convection resistances.arrow_forwardQ. 5: Assume steady-state, one-dimensional heat conduction through the symmetric shape shown in Figure 1. Assuming that there is no internal heat generation, derive an expression for the thermal conductivity k(x) for these conditions: A(x) = (1 - x), T(x) = 300(1 - 2x - x3), and q = 6000 W, where A is in square meters, T in kelvins, and x in meters. Consider x= 0 and 1.arrow_forwardActivity: compile 1 example for each topic: explain: 1. Conductive heat flow through flat surface2. Conductive heat flow throw composite wall3. Conductive heat flow through thick walled tube4. CONDUCTED HEAT FLOW THROUGH THICK SPHERE5. Heat transfer between two fluids separated by walls of a composite tube of solid materials6. Absorption, reflection and transmissionarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning