A sphere of 25 [mm] diamter contains an embedded electric heater. Calculate the power required to...
A sphere of 25 [mm] diamter contains an embedded electric heater. Calculate the power required to maintain the surface temperature at 94 when the sphere is exposed to quiescent medium at 20 for (a) air atmospheric pressure (b) water
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A sphere of 25 [mm] diamter contains an embedded
electric heater. Calculate the power required to...
A cylindrical electric heater is located at the centre of a room. The heater has an...
A cylindrical electric heater is located at the centre of a room. The heater has an outer diameter of 0.05 m, length of 0.6 m and emmisivity of 0.97. The surface temperature of this heater is maintained at 105 °C. The internal dimension of the room is 5m x 10m x 3m. The inner surface of this room's wall and air inside this room is maintained at 20 °C using an air conditioning system. The heat transfer coefficient between the...
1. Consider an opaque, horizontal square plate (Im by 1m) with an electrical heater on its backside. The front side is exposed to ambient quiescent air that is at 20° C, solar irradiation (from...
1. Consider an opaque, horizontal square plate (Im by 1m) with an electrical heater on its backside. The front side is exposed to ambient quiescent air that is at 20° C, solar irradiation (from sun at 5800° K) of 600 W/m2, and an effective sky temperature of -40° C. The plate surface temperature is kept at Ts 60 C (at steady state condition). Calculate natural convection heat transfer coefficient from the plate. (10 points) What is the electrical power (W/m2)...
A 50 mm thick steel plate (AISI347) has a uniform heat flux applied to its bottom...
A 50 mm thick steel plate (AISI347) has a uniform heat flux
applied to its bottom surface by a heater. The heater is in contact
with the steel plate, and the interface between the heater and
steel has a contact resistance of 2.0 x 10-4
m2*K/W. The top surface of the plate is exposed to
surrounding air (T = 20oC, h = 10 W/m2*K) and
exchanges radiation with surroundings at Tsur =
10oC. The emissivity of the plate is 0.85....
6.83 A disk of 20-mm diameter is covered with a water film. Under steady-state conditions, a heat...
6.83 A disk of 20-mm diameter is covered with a water film. Under steady-state conditions, a heater power of 200 mW is required to maintain the disk-water ilm at 305 K in dry air at 295 K and the observed evaporation rate is 2.55 × 10-4 kg/h. Air T 295 K Water film, T 305 K Disk, D = 20 mm Heater, 200 m (a) Calculate the average mass transfer convection (b) Calculate the average heat transfer convection (c) Do...
An electric heaner with a total surface area of 025 m2 and an emissivity of 0...
An electric heaner with a total surface area of 025 m2 and an emissivity of 0 75 is in a room where the air has a temperature of 20'C and the walls are at 10*C. When the heater consumes 500 W of electric power, its surface has a steady temperature of 120 C. Determine the temperature of the heater surface when it consumes 860 w Given ?:567x108 wirm2K4 T.A Section Break Difficulty Medium 5. Reqused indormaton 000 points Soilve the...
3. a) An electric water heater uses 5500 W (240 V) of electrical power. It has...
3. a) An electric water heater uses 5500 W (240 V) of electrical power. It has a capacity of 40 gallons (150 liters or 150 kg). If the initial temperature of the water in the water heater is 20° C, how long will it take to heat the water to a final temperature of 60° C at 100% efficiency? b) How long will it take to heat the water to a final temperature of 60°C at 80% efficiency? c)If electrical...
mm and in a water flow that is at 20'C and What are the 8- A...
mm and in a water flow that is at 20'C and What are the 8- A square chip is of width w 5 mm on a side and is is exposed to the flow of a coolant at T-15°C. From the chip must not exceed T-85°C. If the coolant is air and the chip power? If the coolant is a d liquid for which h 3000 Radiation: 9. Humans are able to control their heat production rate and heat loss...
SP-25 Consider a regenerative steam power plant with one open feedwater heater and one closed fee...
SP-25 Consider a regenerative steam power plant with one open feedwater heater and one closed feedwater heater. Superheated steam enters the turbine with a mass flow rate of 120 kg/s at 16 MPa and 560°C (State 1). Some fraction of the steam is extracted at 40 bar (State 2) and is supplied to the closed feedwater heater. The remaining steam expands to a pressure of 3 bar (State 3), another fraction is extracted at this pressure, and is supplied to...
An electric heater whose total area is 2 ft? and whose volume is 1/12 ft3 is...
An electric heater whose total area is 2 ft? and whose volume is 1/12 ft3 is dissipating elec- trical energy at the rate of 5000 watts-17,000 Btu/hr in the steady state while suspended in a room where the air is at 80 F and the average surface coefficient of heat transfer is 30 Btu/hr ft °F. Suddenly, the heater falls (but remains plugged in) on to a rug on the floor which effectively insulates half the heater. For the heater,...
5 A hollow sphere of inside radius 30 mm and outside radius 50 mm is (5...
5 A hollow sphere of inside radius 30 mm and outside radius 50 mm is (5 electrically heated at its inner surface at a constant rate of 10 KW/m2. The outer surface is exposed to a fluid at 30°C, with heat transfer coefficient of 170 W/m2.K. The thermal conductivity of the material is 20 W/m.K. Calculate *.inner and outer surface temperatures 301.5°C Not all the above 30.15°C. 57.14'c. O 60.14'c. O تقع The handle of a saucepan, 30 cm long...
A cylindrical electric heater is located at the centre of a room. The heater has an outer diameter of 0.05 m, length of 0.6 m and emmisivity of 0.97. The surface temperature of this heater is maintained at 105 °C. The internal dimension of the room is 5m x 10m x 3m. The inner surface of this room's wall and air inside this room is maintained at 20 °C using an air conditioning system. The heat transfer coefficient between the...
1. Consider an opaque, horizontal square plate (Im by 1m) with an electrical heater on its backside. The front side is exposed to ambient quiescent air that is at 20° C, solar irradiation (from sun at 5800° K) of 600 W/m2, and an effective sky temperature of -40° C. The plate surface temperature is kept at Ts 60 C (at steady state condition). Calculate natural convection heat transfer coefficient from the plate. (10 points) What is the electrical power (W/m2)...
A 50 mm thick steel plate (AISI347) has a uniform heat flux
applied to its bottom surface by a heater. The heater is in contact
with the steel plate, and the interface between the heater and
steel has a contact resistance of 2.0 x 10-4
m2*K/W. The top surface of the plate is exposed to
surrounding air (T = 20oC, h = 10 W/m2*K) and
exchanges radiation with surroundings at Tsur =
10oC. The emissivity of the plate is 0.85....
6.83 A disk of 20-mm diameter is covered with a water film. Under steady-state conditions, a heater power of 200 mW is required to maintain the disk-water ilm at 305 K in dry air at 295 K and the observed evaporation rate is 2.55 × 10-4 kg/h. Air T 295 K Water film, T 305 K Disk, D = 20 mm Heater, 200 m (a) Calculate the average mass transfer convection (b) Calculate the average heat transfer convection (c) Do...
An electric heaner with a total surface area of 025 m2 and an emissivity of 0 75 is in a room where the air has a temperature of 20'C and the walls are at 10*C. When the heater consumes 500 W of electric power, its surface has a steady temperature of 120 C. Determine the temperature of the heater surface when it consumes 860 w Given ?:567x108 wirm2K4 T.A Section Break Difficulty Medium 5. Reqused indormaton 000 points Soilve the...
3. a) An electric water heater uses 5500 W (240 V) of electrical power. It has a capacity of 40 gallons (150 liters or 150 kg). If the initial temperature of the water in the water heater is 20° C, how long will it take to heat the water to a final temperature of 60° C at 100% efficiency? b) How long will it take to heat the water to a final temperature of 60°C at 80% efficiency? c)If electrical...
mm and in a water flow that is at 20'C and What are the 8- A square chip is of width w 5 mm on a side and is is exposed to the flow of a coolant at T-15°C. From the chip must not exceed T-85°C. If the coolant is air and the chip power? If the coolant is a d liquid for which h 3000 Radiation: 9. Humans are able to control their heat production rate and heat loss...
SP-25 Consider a regenerative steam power plant with one open feedwater heater and one closed feedwater heater. Superheated steam enters the turbine with a mass flow rate of 120 kg/s at 16 MPa and 560°C (State 1). Some fraction of the steam is extracted at 40 bar (State 2) and is supplied to the closed feedwater heater. The remaining steam expands to a pressure of 3 bar (State 3), another fraction is extracted at this pressure, and is supplied to...
An electric heater whose total area is 2 ft? and whose volume is 1/12 ft3 is dissipating elec- trical energy at the rate of 5000 watts-17,000 Btu/hr in the steady state while suspended in a room where the air is at 80 F and the average surface coefficient of heat transfer is 30 Btu/hr ft °F. Suddenly, the heater falls (but remains plugged in) on to a rug on the floor which effectively insulates half the heater. For the heater,...
5 A hollow sphere of inside radius 30 mm and outside radius 50 mm is (5 electrically heated at its inner surface at a constant rate of 10 KW/m2. The outer surface is exposed to a fluid at 30°C, with heat transfer coefficient of 170 W/m2.K. The thermal conductivity of the material is 20 W/m.K. Calculate *.inner and outer surface temperatures 301.5°C Not all the above 30.15°C. 57.14'c. O 60.14'c. O تقع The handle of a saucepan, 30 cm long...
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