a 1 m-wide by 2 m-high window is composed of two 5 mm-thick glass panes, seperated by an air space of 10 mm. the temperature at the inner and outer surfaces of the window are 15 C and -20 C respectively. If the thermal conductivities of the glass pane and the air space are 1.4 w/m-k and 0.024 w/m-k, respectively. find the total conduction thermal resistance of the window in k/w

a 1 m-wide by 2 m-high window is composed of two 5 mm-thick glass panes, seperated by an air space of 10 mm. the temperature at the inner and outer surfaces of the window are 15 C and -20 C respectively. If the thermal conductivities of the glass pane and the air space are 1.4 w/m-k and 0.024 w/m-k, respectively. find the total conduction thermal resistance of the window in k/w

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.1P: 1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed...

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1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.
1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed to temperature of –5°C, while the inner surface is kept at 20°C. The thermal conductivity of the concrete is 1.2 W/m K. Determine the heat loss through the wall, which is 10-m long and 3-m high. Problem 1.1
2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be K. With this information determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall.
2.55 A long, 1-cm-diameter electric copper cable is embedded in the center of a 25-cm-square concrete block. If the outside temperature of the concrete is 25oC and the rate of electrical energy dissipation in the cable is 150 W per meter length, determine temperatures at the outer surface and at the center of the cable.
It is designed in such a way that the internal temperature of a commercial heat treatment furnace can reach up to 165 oC. All surfaces of the furnace consist of firebrick (10 cm), insulation material and sheet metal (3mm) from the inside out. Given that the outdoor temperature is 22 oC, the outer sheet will be allowed to go up to 35 oC, which is a temperature that will not disturb in contact with hands. In this case, determine the insulation material thickness to be used. The thermal conductivity coefficient of the insulation material is insulation 0.066 W / m oC, 60 W / m oC for sheet metal and 115 W / m oC for firebrick. Indoor heat transfer coefficient will be accepted as 25 W / m2 oC and 12 W / m2 oC for outdoor environment.
A wall in a house contains a single window. The window consists of a single pane of glass whose area is 0.13 m2 and whose thickness is 8 mm. Treat the wall as a slab of the insulating material Styrofoam whose area and thickness are 19 m2 and 0.10 m, respectively. Heat is lost via conduction through the wall and the window. The temperature difference between the inside and outside is the same for the wall and the window. Of the total heat lost by the wall and the window, what is the percentage lost by the window?
It is designed in such a way that the internal temperature of a commercial heat treatment furnace can reach up to 165 oC. All surfaces of the furnace consist of firebrick (10 cm), insulation material and sheet metal (3mm) from the inside out. Given that the outdoor temperature is 22 oC, the outer sheet will be allowed to go up to 35 oC, which is a temperature that will not be disturbed by hand contact. In this case, determine the insulation material thickness to be used. Insulation material thermal conductivity coefficient is 0.066 insulation W / m oC, 60 W / m oC for sheet metal and 115 W / m oC for firebrick. Indoor heat transfer coefficient will be accepted as 25 W / m2 oC and 12 W / m2 oC for outdoor environment.
A wall is made of firebricks 9 inches thick and has a 700F difference in the temperature of both sides. Calculate the heat transferred through the wall if the thermal conductivity of the bricks is 0.65 BTU/hr-ft-0
A cubical tank of 2 m sides is constructed of special metal plate 12 mm and contains water at 75°C. The surrounding air temperature is 16°C. Calculate the overall heat transfer coefficient from water to air. Take the coefficient of thermal conductivity of the metal as 48 W/m-K, the coefficient of heat transfer of water is 2.5 kW/m2-K and the coefficient of heat transfer of the air is 16 W/m2-K.
A furnace wall consists of 2 ft of brick . The brick has athermal conductivity of 0.6 Btu/ hr sq ft ( ° F /ft), a specific heat of0.2 Btu/ lb ° F, and a density of 110 lb/cu ft. The temperature atthe inside surface of the wall is 1100 ° F , and at the outside surface,200 ° F .(a) Calculate the thermal diffusivity of the brick .(b) Calculate the heat loss per hour through a wall 10 ft high and10 ft long(c ) Calculate
A metal furnace with a 1.25 m x 0.75 m metal door is placed in a room and set to 400K. A 0.3 m x 0.3 m glass window is located in the furnace door. The thickness of the metal alloy and the glass window are 3 mm and 2 mm, respectively. The glass window has a thermal conductivity (k) of 0.7 W/m .K and the metal door has a thermal conductivity (k) of 3.5 W/m.K. The convective heat coefficient hi and ho on each site of the furnace door is estimated as 10W/m2.K. Assuming the room temperature is held constant at 297 K, calculate the total heat loss from the furnace door. P.S Could you write the solution clearly to better understanding? Step by step using formulas. Another page with detailed steps would be better. Thanks in advance.
A steam bath center in a gym consists of a wall three different material layers. First two layers have thermal conductivity of 5 W/m K, 10 W/m K and 2*(10) W/m K respectively. All three layers have thickness of 8 cm each. The inside wall surface temperature of steam room is 80 °C whereas outside surface temperature is 25 °C. Draw this composite wall. Calculate the heat transfer per unit length of the wall.