**Problem 5.78**Spheres of 40-mm diameter, heated to a uniform temperature of 400°C, are suddenly removed from the oven and placed in a forced-air bath operating at 25°C with a convection coefficient of 300 W/m²·K on the sphere surfaces. The thermophysical properties of the sphere material are:- Density \( \rho = 3000 \, \text{kg/m}^3 \)- Specific heat capacity \( c = 850 \, \text{J/kg·K} \)- Thermal conductivity \( k = 15 \, \text{W/m·K} \)**(a)** How long must the spheres remain in the air bath for 80% of the thermal energy to be removed?**(b)** The spheres are then placed in a packing carton that prevents further heat transfer to the environment. What uniform temperature will the spheres eventually reach?

The spheres remain in the air bath for 80% is 98.6 second Uniform temperature will be 1000C

Spheres of 40-mm diameter heated to a uniform temperature of 400°C are suddenly removed from the oven and placed in a forced-air bath operating at 25°C with a convection coefficient of 300 W/m² K on the sphere surfaces. The thermophysical properties of the sphere material are p = 3000 kg/m³, c = 850 J/kg-K, and k = 15 W/m.K. (a) How long must the spheres remain in the air bath for 80% of the thermal energy to be removed?

Spheres of 40-mm diameter heated to a uniform temperature of 400°C are suddenly removed from the oven and placed in a forced-air bath operating at 25°C with a convection coefficient of 300 W/m² K on the sphere surfaces. The thermophysical properties of the sphere material are p = 3000 kg/m³, c = 850 J/kg-K, and k = 15 W/m.K. (a) How long must the spheres remain in the air bath for 80% of the thermal energy to be removed?

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

A 200mm diameter spherical steel ball initially at 500°C is rapidly immersed in an oil bath that is at 20°C. The convection coefficient is h = 600W/m²-K, and the steel ball has the following properties: c= 500J/kg-K, p= 7000kg/m³, k=30W/m-K. Determine the time taken (min) for temperature at the surface of the ball to drop to 100°C.
The rear window of an automobile is defogged by passing warm air over its inner surface. If the warm air is at T∞,i=40°C and the corresponding convection coefficient is hi=30 W/m2·K, what are the inner and outer surface temperatures, in °C, of 4-mm-thick window glass, if the outside ambient air temperature is T∞,o= -27.5°C and the associated convection coefficient is ho=65 W/m2·K? Evaluate the properties of the glass at 300 K. a. what is the heat flux through the original walls in W/ m^2? b. what is the heat flux through the retrofitted walls in w /m^2?
Can someone please help me to solve all of the following question showing all work and explanation as well as graphs needed in excel with formulas. Thank you!
= A long rod of 60-mm diameter and thermophysical properties p 8000 kg/m³, c C = 500 J/kg-K, and k = 50 W/m-K is initially at a uniform temperature and is heated in a forced convection furnace maintained at 750 K. The convection coefficient is estimated to be 1000 W/m².K. What is the centerline temperature of the rod when the surface temperature is 570 K? The centerline temperature of the rod is i K.
Small potato balls of 0.5 cm radius (can be approximated as a sphere) baked in the oven and initially at a uniform temperature of 160°C. Assume, potatoes have a density of 650 kg/m, specific heat of 3400 J/kgK and conductivity of 1 W/mK. You want to eat potatoes quickly without burning your tongue so that you have decided to cool them down with forced convection. Air h, T. hot potato initially Air temperature is 20°C and the convective heat transfer coefficient is 140 W/m?K. Calculate the time (in seconds) required for its surface temperature to drop 90°C.
Question is image
The rear window of an automobile is defogged by passing warm air over its inner surface. If the warm air is at T = 40°C and the 30 W/m2-K, what are corresponding convection coefficient is h; the inner and outer surface temperatures, in °C, of 4-mm-thick window glass, if the outside ambient air temperature is To || 0,0 -30°C and the associated convection coefficient is ho W/m2-K? Evaluate the properties of the glass at 300 K. = 65 Tsi i °C Ts.0 °C T5,0 i
I need the answer as soon as possible
Heat transfer
The main body of plenum is a steel vessel of diameter 0.1meters has two semicircle domed ends. During operation is will contain mix of fuel and air at approximately 250OC. The wall of the vessel is 0.03meters thick and the plenum is 0.45meters long. Estimate the rate of heat loss from the vessel when the outside air temperature is 45OC. The thermal conductivity of steel is 45 W/m K and the surface heat transfer coefficient on the air side is 8 W/m2 . On the inside it is 65W/m2 . If it was possible to clad the plenum calculate the reduction in the rate of heat loss. Assume the lagging would be 5mm thick and has a thermal conductivity of 0.05 W/m.
(B) Cylindrical Water cans (diameter 6.5cm and length 15cm) are to be cooled from initial temperature of 20°C by placing theme in a cooler with ambient temperature of 1°C. Compare the initial cooling rates when the cans are laid horizontally to when the cans are laid vertically. Take v = 15.55x10° m²/s, k=0.024 W/mK and Pr=0.7. Nu = 0.53RA' a4 for horizontal orientation Nu = 0.59 Ra"4 for vertical orientation
Can you help me answer my sample problem for my review?