QUESTION 44 A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 'C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mk) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m-K and 14.5 W/m2K respectively, calculate: the resistance(R) for the Aluminium near the outer thermal layer in K/W to 8 decimal places.

QUESTION 44 A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 'C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mk) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m-K and 14.5 W/m2K respectively, calculate: the resistance(R) for the Aluminium near the outer thermal layer in K/W to 8 decimal places.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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a) A 50 mm diameter carbon steel tube (ρ=7833 kg/m³; Cp = 465 J/kg.K, k = 54 W/mK) at an initial uniform temperature of 18°C is heated in an oven with air circulation that is at a temperature of 250°C and has a convection heat transfer coefficient of 45 W/m².K. How long must the tube be in the oven for the surface temperature to reach 100°C? b) The figure below illustrates the temperature distribution inside a flat solid at two instants for two different situations (A and B). In both situations is there heat transfer? What causes them to behave differently?
A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: the resistance(R) for the Aluminium near the outer thermal layer in K/W to 8 decimal places. the resistance(R) for the Aluminium near the inner thermal layer in K/W to 8 decimal places.
A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: the resistance(R) for the outer fluid thermal layer in K/W to 5 decimal places.
QUESTION 58 A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 °C. The bodies consist of two 10-mm-thick layers of Aluminium (k 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces 11.6 W/m2K and 14.5 W/m2K are respectively, calculate: the outer surface temperature of the Aluminum in °C to 2 decimal places.
A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: the resistance(R) for the Aluminium near the outer thermal layer in K/W to 8 decimal places this question is from thermodynamics
A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 ˚C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m2K and 14.5 W/m2K respectively, calculate: the resistance(R) for the Aluminium near the inner thermal layer in K/W to 8 decimal places.
2- 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. There are to be 100 fins per meter. The convective heat transfer coefficient, both for the wall and the fins, is estimated at 35 W/(m2 K). With this information, determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall. (take the case where the tip is exposed to convection) Ans(48 t= 2.5 mm 2.5 cm
QUESTION 1 A domestic refrigerator with Inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to malntaln a set temperature of 6 "C. The bodies consist of two 10-mm-thick layers of Aluminium (k - 225 WmK) separated by a 30 mm polyurethane Insulation (k-0.028 WimK). If the average convection heat transter coefficient at the Inner and outer surfaces are 11.6 W/m2k and 14.5 W/m2K respectively, calculate: the resistance(R) for the Aluminium near the inner thermal layer in K/W to 8 decimal places. QUESTION 2 A domestic refrigerator with Inner dimensions of 0.7 m by 0.7 m at the base and helght 1 m was designed to malntaln a set temperature of 6 "C. The bodies consist of two 10-mm-thick layers of Aluminium (k - 225 W/mK) separated by a 30 mm polyurethane Insulation (k-0.028 WimK). If the average convection heat transfer coefficlent at the Inner and outer surfaces are 11.6 W/m2K and 14.5 W/mK respectively, calculate: the resistance(R) for the Aluminium near the outer…
QUESTION 15 A domestic refrigerator with inner dimensions of 0.7 m by 0.7 m at the base and height 1 m was designed to maintain a set temperature of 6 °C. The bodies consist of two 10-mm-thick layers of Aluminium (k = 225 W/mK) separated by a 30 mm polyurethane insulation (k=0.028 W/mK). If the average convection heat transfer coefficient at the inner and outer surfaces are 11.6 W/m²K and 14.5 W/m2K respectively, calculate: the resistance(R) for the outer fluid thermal layer in K/W to 5 decimal places.
The composite wall of an oven consists of three materials, with thermal conductivity, KA = 20 W/ m. kg = 30 W/ m. K, kc = 50 W/m. K, and known thickness, LA =30 cm,, LB =20 cm and Lc = 15 cm. Under steady- state operating conditions, measurements reveal an outer surface temperature of Tso =20°C, an inner surface temperature of Tsi = 600°C. The inside and outside convection coefficients are 25 W/m2. K and 15 W/m2. K. The wall repeats itself every 25 cm distance in the vertical direction and if the wall is 1-m deep and 0.25-m high, then assume an area of 0.25m2 for all your calculations. Find the total resistance. T- 600°c T 20°c Air T, h Select one: O a. 10.525°C/W O b. 5.526°C/W O c. 0.526°C/W
Hint: You found out where is the maximum temperature.