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 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 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 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...
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 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...
This is for the subject of Heat Transfer. Any clues on how to solve this would be greatly appreciated thanks 2 [ABET]) An electric cable of radius ri andTaur thermal conductivity ke is enclosed by an insulating sleeve whose outer surface is of radius r2 and experiences convection heat transfer and radiation exchange with the adjoining air and large surroundings, respectively. When electric current passes through the cable, thermal energy is generated within the cable at a volumetric rate q....