2. An aluminum cylinder has a radius (ra) of 3 cm and al n cylinder has...
Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct of inner cross section of 25x25cm at a mass flow rate of 1.0 kg/s. The duct is exposed to air at 35°C with a combined convection-radiation heat transfer coefficient of 15 W/m2K. The convection heat transfer coefficient at the inner surface is 75 W/.m2.K. If the air temperature in the duct should not increase by more than 1°C determine the maximum...
P2) (50 pts.) A sphere of radius , and thermal conductivity of k=0.1 W/ mK is generating heat at a constant rate in W/m] inside another sphere of radius ry. The radius of the internal sphere is a 10 cm and the radius of the outer sphere is 40 cm. The outer surface is exposed to ambient air at 27°C and a convection coethicient -30 W/m-K. The thermal conductivity of the external sphere is 6.0 W/m-K. If the temperature at...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is generated uniformly in the wire as a result of resistance heating at a constant rate of 0.5 W/cm3. The wire is covered with polyethylene insulation with a thickness of 0.25 cm and thermal conductivity of ks 0.4 W/m K. The outer surface of the insulation is subjected to free convection in air at 20°C and a convection heat transfer coefficient of 2...
Q1) Inner surface of a side wall is used for heating of ambient-room air as shown below. There is an electrical heater with 10 W/m2 heat flux generation between a layer of insulation and 2 cm thick marble exposed to ambient-room air at T-20 °C with h-20 W/m2K. k-0.04 W/mK Marble with a thickness of 2 cm Ts= 10 ℃ outside Ambient-room air at To Electrical heating layer (negligible thickness) of temperature T-? Insulation with a thickness of 5 cm...
The roof ceiling has the following assembly: 1) metal structure slab: conductivity k1=4.0 W/mK, thickness L1=0.5 cm, 2) Polystyrene: k2=0.05 W/mK, L2=10 cm, 3) Ceiling tiles: k3=0.5 W/mK, L3=1.0 cm. Internal and external convection coefficients are: hinternal= 8 W/m2K and hexternal= 24 W/m2K. a) (2 points) Calculate the resistance of Concrete slab, Polystyrene, and Gypsum wall board. b) (1 point) Considering the insulation properties, which assembly component is the most important? Rank themaccording to the thermal insulation contribution. c) (2 points)...
The solar radiation incident on the outside surface of an aluminum shading device is 1300 W/m2 . Aluminum absorbs 10% of the incident solar energy, and dissipates it by convection from the back surface and by combined convection and radiation from the outside surface. The convection heat transfer coefficient is 10 W/m2 ·K for both surfaces, and the ambient/surrounding temperature can be taken 20 °C for both convection and radiation. Assuming that the aluminum shade has a uniform temperature, determine...
IF YOU CANNOT SOLVE THEM ALL THEN PLEASE DONT SOLVE ANY. A hollow aluminum sphere, with an electrical heater in the center, is used in tests to determine the thermal conductivity of insulating materials. The inner and outer radii of the sphere are 0.15 and 0.18 m, respectively, and testing is done under steady-state conditions with the inner surface of the aluminum maintained at 250°C. In a particular test, a spherical shell of insulation is cast on the outer surface...
A plane wall is composed of two materials. Material A has a uniform heat generation of 100 kW/m3, a thermal conductivity of 50 W/mK, and a thickness of 10 cm. The inner surface of material A is well insulated. The other surface of material A is connected to Material B which has no generation with a thermal conductivity of 100 W/mK and a thickness of 20 cm. The outer surface of material B is cooled by ambient air at 300...
Superheated steam flows steadily through steel tubing (k 35 W/m-K) applying a tube inner surface temperature of 575°C. The tubing has an inner diameter of 300 mm and a wall thickness of 30 mm. Insulation (k 0.10 W/m-K) is applied to the outer surface of the tube while thin aluminum sheet is applied around the insulation as a protective covering. The ambient air at 27°C provides a convection coefficient of 6 W/m2-K. Determine the minimum insulation thickness necessary (mm) to...
I. Steam at 220°C İs transported through an AISI 101 0 carbon steel pipe. The inside and outside diameters of the pip glass pipe insulation. e are 12 and 13 cm respectively. The pipe is wrapped with 5 cm thick cellular The ambient air temperature is 8°C. The inside and outside convection heat nts are 95 and 15 W/m2-K respectively. The thermal conductivity of the pipe is 60 W/m-K and for the insulation it is 0.072 W/m-K a. Construct the...