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A 50 mm x 45 mm x 20 mm cell phone charger has a surface temperature...
Homework 7 heat transfer 2018-20 1) A horizontal tube of 12.5-mm dimeter with an outer srface temperature of 240°C is placed in a room with an air temperature of 20°C. Estimate the heat transfer rate...
Homework 7 heat transfer 2018-20 1) A horizontal tube of 12.5-mm dimeter with an outer srface temperature of 240°C is placed in a room with an air temperature of 20°C. Estimate the heat transfer rate per unit length of the tube due to free convection. 2) Air at -10°C flows at 10 m/s over the roof plate of two 5m length rooms whose air is at Too-200C. The roof plate is 0.20-m thick concrete (k = 0.6 w/ m. K)....
Water enters through a thick-walled tube having inner and outer diameters of 19 and 38 mm and 20 m long
Water enters through a thick-walled tube having inner and outer diameters of 19 and 38 mm and 20 m long The inlet temperature is Tmi=17℃ and outlet temperature is Tmo = 50°C. The outer surface of the tube is well Insulated, and electrical heating within the wall provides for a uniform generation rate of q = 8X105 W/m3. If the inner surface temperature of the tube Ts = 60 °C at the outlet what is the local convection heat transfer...
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....
3. A small cylindrical filament is heated in a large combination convection-radiation oven. The filament has...
3. A small cylindrical filament is heated in a large combination convection-radiation oven. The filament has a diameter D= 50 mm and length L= 1 m. During the process, the oven wall temperature is fixed at Tsur=800 K, and the hot air is blowing with a temperature T.= 500 K and an average heat transfer coefficient h=50 W/m²K. Assuming the filament surface is opaque and diffuse, and it has a spectral emissivity as shown below: (25 pts) The oven walls behave...
A rod of 10-mm diameter and 250-mm length has one end maintained at 100°C
A rod of 10-mm diameter and 250-mm length has one end maintained at 100°C. The surface of the rod experiences free convection with the ambient air at 25°C and a convection coefficient that depends on the difference between the temperature of the surface and the ambient air. Specifically, the coefficient is prescribed by a correlation of the form, hfc = 2.89[0.6 +0.624(T - T∞)1/6]2, where the units are hfc (W/m².K) and T (K). The surface of the rod has an...
P1 (50 pts.) - A large plane wall has a thickness L-60 cm and thermal conductivity...
P1 (50 pts.) - A large plane wall has a thickness L-60 cm and thermal conductivity k 25 W/m-K. On the left surface (x-0), it is subjected to a uniform heat flux qo while the surface temperature To is constant. On the right surface, it experiences convection and radiation heat transfer while the surface temperature is TL-225°C and the surrounding temperature is 25°C. The emissivity and the convection heat transfer coefficient on the right surface are 0.7 and 15 W/m2-K,...
list the assumptions (if appropriate), provide a sketch (if appropriate) A thin flat plate of length L-120 mm, thicknes...
list the assumptions (if appropriate), provide a sketch
(if appropriate)
A thin flat plate of length L-120 mm, thickness t=4 mm, width W=30 mm, and thermal conductivity k-20 W/m-K is thermally joined to heat sinks at different temperatures, where T(x 0) = To-100°C and T(x = L) Ti-35°C. The top surface of the plate is subjected to uniform heat flux q"-20 kW/m2, and the bottom surface of the plate is subjected to uniform convection with a convection coefficient of h-50...
Liquid flows in a metal pipe with an inner diameter of D1 = 22 mm and...
Liquid flows in a metal pipe with an inner diameter of D1 = 22 mm and an outer diameter of D2 = 32 mm. The thermal conductivity of the pipe wall is 12 W/m·K. The inner surface of the pipe is coated with thin polyvinylidene chloride (PVDC) lining. Along a length of 1 m, the pipe outer surface is exposed to convection heat transfer with hot gas, at T∞ = 100°C and h = 5 W/m2·K, and thermal radiation with...
A 6-mm-diameter electrical transmission line carries an electric current of 50 A. If the surface temperature...
A 6-mm-diameter electrical transmission line carries an electric current of 50 A. If the surface temperature of the wire is T.-11.0°C during a windy day when the air temperature is 10°C and the wind is blowing across the transmission line at 40 km/h, which is the heat loses in one kilometer of transmission line. Air properties: p= 1.246 kg/m”, k = 0.02439 W/m. C, u=1.426x10* mºis, Pr = 0.7336 Wind, 40 km/h 100/14 Transmission lines
NE Steel tubes (k =35 W/m2.K) of 400-mm inner diameter and 30-mm wall thickness are used...
NE Steel tubes (k =35 W/m2.K) of 400-mm inner diameter and 30-mm wall thickness are used to route superheated steam from the boller to the turbine in a power plant. Safety and economic concerns make it practical to add a 200-mm layer of Insulation (k =0.1 W/mK) to each tube, which is wrapped in a thin sheet of aluminum with an emissivity e =0.15. The air (with a convective coefficient h =5 W/m2K) and wail temperatures of the plant are...
Homework 7 heat transfer 2018-20 1) A horizontal tube of 12.5-mm dimeter with an outer srface temperature of 240°C is placed in a room with an air temperature of 20°C. Estimate the heat transfer rate per unit length of the tube due to free convection. 2) Air at -10°C flows at 10 m/s over the roof plate of two 5m length rooms whose air is at Too-200C. The roof plate is 0.20-m thick concrete (k = 0.6 w/ m. K)....
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....
3. A small cylindrical filament is heated in a large combination convection-radiation oven. The filament has a diameter D= 50 mm and length L= 1 m. During the process, the oven wall temperature is fixed at Tsur=800 K, and the hot air is blowing with a temperature T.= 500 K and an average heat transfer coefficient h=50 W/m²K. Assuming the filament surface is opaque and diffuse, and it has a spectral emissivity as shown below: (25 pts) The oven walls behave...
P1 (50 pts.) - A large plane wall has a thickness L-60 cm and thermal conductivity k 25 W/m-K. On the left surface (x-0), it is subjected to a uniform heat flux qo while the surface temperature To is constant. On the right surface, it experiences convection and radiation heat transfer while the surface temperature is TL-225°C and the surrounding temperature is 25°C. The emissivity and the convection heat transfer coefficient on the right surface are 0.7 and 15 W/m2-K,...
list the assumptions (if appropriate), provide a sketch
(if appropriate)
A thin flat plate of length L-120 mm, thickness t=4 mm, width W=30 mm, and thermal conductivity k-20 W/m-K is thermally joined to heat sinks at different temperatures, where T(x 0) = To-100°C and T(x = L) Ti-35°C. The top surface of the plate is subjected to uniform heat flux q"-20 kW/m2, and the bottom surface of the plate is subjected to uniform convection with a convection coefficient of h-50...
A 6-mm-diameter electrical transmission line carries an electric current of 50 A. If the surface temperature of the wire is T.-11.0°C during a windy day when the air temperature is 10°C and the wind is blowing across the transmission line at 40 km/h, which is the heat loses in one kilometer of transmission line. Air properties: p= 1.246 kg/m”, k = 0.02439 W/m. C, u=1.426x10* mºis, Pr = 0.7336 Wind, 40 km/h 100/14 Transmission lines
NE Steel tubes (k =35 W/m2.K) of 400-mm inner diameter and 30-mm wall thickness are used to route superheated steam from the boller to the turbine in a power plant. Safety and economic concerns make it practical to add a 200-mm layer of Insulation (k =0.1 W/mK) to each tube, which is wrapped in a thin sheet of aluminum with an emissivity e =0.15. The air (with a convective coefficient h =5 W/m2K) and wail temperatures of the plant are...
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