A short brass cylinder (p= 8530 kg/m³, cp=0.389 kJ/kg-K, k=110 W/m-K, and a = 3.39×10−5 m²/s) of diameter 4 cm and height 20 cm is initially at a uniform temperature of 140°C. The cylinder is now placed in atmospheric air at 20°C, where heat transfer takes place from the cylinder 15 min after the start of the cooling by convection with a heat transfer coefficient of 40 W/m2.K. Solve this problem using the analytical one-term approximation method. Interpolate table 4-2 to obtain constants and A₁. For Biot number values less than 0.01 approximate it as 0.01 for use in Table 4-2. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. 20 cm Brass cylinder 4 cm- T:°C Ambient air 20°C Calculate the center temperature of the top surface of the cylinder. The center temperature of the top surface of the cylinder is 61 °C.

A short brass cylinder (p= 8530 kg/m³, cp=0.389 kJ/kg-K, k=110 W/m-K, and a = 3.39×10−5 m²/s) of diameter 4 cm and height 20 cm is initially at a uniform temperature of 140°C. The cylinder is now placed in atmospheric air at 20°C, where heat transfer takes place from the cylinder 15 min after the start of the cooling by convection with a heat transfer coefficient of 40 W/m2.K. Solve this problem using the analytical one-term approximation method. Interpolate table 4-2 to obtain constants and A₁. For Biot number values less than 0.01 approximate it as 0.01 for use in Table 4-2. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. 20 cm Brass cylinder 4 cm- T:°C Ambient air 20°C Calculate the center temperature of the top surface of the cylinder. The center temperature of the top surface of the cylinder is 61 °C.

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

See similar textbooks

Similar questions

An ordinary egg can be approximated as a 5.5-cmdiameter sphere. The egg is initially at a uniform temperature of 88C and is dropped into boiling water at 97C. Taking the properties of the egg to be r = 1020 kg/m3 and cp = 3.32 kJ/kg·8C, determine (a) how much heat is transferred to the egg by the time the average temperature of the egg rises to 70C and (b) the amount of entropy generation associated with this heat transfer process.
The chilling room of a meat plant is 15 m × 18 m × 5.5 m in size and has a capacity of 350 beef carcasses. The power consumed by the fans and the lights in the chilling room are 22 and 2 kW, respectively, and the room gains heat through its envelope at a rate of 14 kW. The average mass of beef carcasses is 220 kg. The carcasses enter the chilling room at 35C, after they are washed to facilitate evaporative cooling, and are cooled to 16°C in 12 h. The air enters the chilling room at 2.2°C and leaves at 0.5°C. Determine (a) the refrigeration load of the chilling room and (b) the volume flow rate of air. The average specific heats of beef carcasses and air are 3.14 and 1.0 kJ/kg · °C, respectively, and the density of air can be taken to be 1.28 kg/m3 .
A refrigeration plant stored 10 metric tons of eggs at a temperature of 15°C. To preserve the eggs by not spoiling them, they have to be cooled at -8°C. What is the refrigerating capacity of the plant in TOR if it is cooled for 12 hours? The specific heat of the eggs above and below freezing are 0.95 kcal/kg-°C and 0.4 kcal/kg-°C, respectively. The latent heat of fusion is 68.5 kcal/kg The freezing temperature is -3°C.
A 1200-W electric resistance heating element whose diameter is 0.5 cm is immersed in 34 kg of water "cp=4.18 kJ/kg.K" initially at 20 C. Assuming the water container is well-insulated. How long it will take for this heater to raise the water temperature to 50 C "Seconds"?
Carbon steel cubes (side = 8 mm, ρ = 7833 kg/m3, k = 54 W/m·°C, Cp = 0.465 kJ/kg·°C, and α = 1.474x10-6 m2/s) are annealed by heating them first to 850°C in a furnace and then allowing them to cool slowly to 95°C in ambient air at 28°C. What is the total rate of heat transfer from the cubes to the ambient air, when 2700 cubes are to be annealed per hour (in Watts)?
THERMOFLUID A student living in a 3-m X 4-m X 4-m dormitory room turns on her 100-W fan before she leaves the room on a summer day, hoping that the room will be cooler when she comes back in the evening. Assuming all the doors and heat trans windows are tightly closed and disregarding any heat fer let through the walls and the windows, determine the temperature in the room when she comes back 8 h later. Use specific heat values at room temperature, and assume room to be at 100 kPa and 20°C in the morning she leaves.
An ice chest whose outer dimensions are 30 cm x 40 cm x 40 cm is made of 3-cm-thick Styrofoam (k = 0.033 W/m °C). Initially, the chest is filled with 28 kg of ice at 0°C, and the inner surface temperature of the ice chest can be taken to be 0°C at all times. The heat of fusion of ice at 0°C is 333.7 kJ/kg, and the surrounding ambient air is at 25°C. Disregarding any heat transfer from the 40 cm x 40 cm base of the ice chest, determine how long it will take for the ice in the chest to melt completely if the outer surfaces of the ice chest are at 8°C. T = 25°C Ice chest D 0°C 3 ст 0°C Styrofoam
Stainless steel ball bearings (r = 8085 kg/m3, k =15.1 W/m·°C, cp = 0.480 kJ/kg·°C, and a = 3.91 * 10-6 m2/s) having a diameter of 1.2 cm are to be quenched in water. The balls leave the oven at a uniform temperature of 900°C and are exposed to air at 30°C for a while before they are dropped into the water. If the temperature of the balls is not to fall below 850°C prior to quenching and the heat transfer coefficient in the air is 125 W/m2·°C, determine how long they can stand in the air before being dropped into the water.
A short brass cylinder (8530 kg/m3,Cp = 0.389 kJ/kg · °C, k =110 W/m · °C, andα= 3.39 x 10-5 m2/s) of diameter D =8 cm and height H = 15 cm is initially at a uniform temperature of Ti= 150°C. The cylinder is now placed in atmospheric air at 20°C, where heat transfer takes place by convection with a heat transfer coefficient of h =40 W/m2 · °C. Calculate (a) the center temperature of the cylinder, b) the center temperature of the top surface of the cylinder and (c) the total heat transfer from the cylinder 15 min after the start of the cooling. Answer: a) 85.1 ℃, b) 84.2℃, c) 164 kJ
In determining the average rate of heating of a tank of 20% sugar syrup, thetemperature at the beginning was 20°C and it took 30 min to heat to 80°C. Thevolume of the sugar syrup was 50 ft3 and its density 66.9 lb/ft3. The specific heat ofthe sugar syrup is 0.9 Btu lb-1°F-1.(a) Convert the specific heat to kJ kg-1°C-1.(b) Determine the rate of heating, that is the heat energy transferred in unit time, in SI units (kJ s-1)
In an aluminum container weighing 0.30 kg are 0.70 kg of water in thermal equilibrium at a temperature of 70°C. Container and water temperature together cool at a rate of 2.5 K/min. What is the heat flux leaking from the container?
A mass of ice at -7OC is needed to cool 114 kg of vegetables (Cp = 3.35 KJ /kg.K )ina bunker for 24 hours . The initial temperature of the vegetables is assumed to be 29OC . It is also assumed that the average temperature in the bunker is 7OC within the 24 -hour period . If the heat gained per hour in the bunker is 25% of the heat removed to thevegetables from 30 OC to 8OC, what would be the required mass of ice ?