Q2) A constant heat flux (a -50 W/m2) is applied to a 1-D plane wall (k...
A concrete slab (k = 1.4 W/m·K) is subjected to a heat flux of 450 W/m2. The slab sits on the ground, which is at a temperature of -8°C, and it is desired to keep the temperature at the upper surface of the slab at 20°C. Determine the thickness of the slab. Ans: (a) L=
Problem 2: Consider a large plane slab of semi-thickness L = 0.3 m, thermal conductivity k = 2.5 W/m K and surface area A = 20.0 m². Both sides of the slab is maintained at a constant wall temperature of 358°K while it is subjected to a uniform but constant heat flux of 950.0 W/m2 Evaluate the temperature distribution/profile within the wall. Calculate the heat flux and temperature at location x = 0.1m. Problem 3: Consider a 10.0 m long...
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,...
Heat is uniformly generated at the rate of 2x 10W/m* in a wall of thermal conductivity 25 W/m-K and thickness 60 mm. The wall is exposed to convection on both sides, with different heat transfer coefficients and temperatures as shown. There are straight rectangular fins on the right-hand side of the wall, with dimensions as shown (L =20 mm) and thermal conductivity of 250 W/m-K. What is the maximum temperature that will occur in the wall? L tt-2 mm k=25...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
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...
The heat generation rate in a plane wall of 0.24 m thickness is 0.4 MW/m3 . The wall is exposed on both sides to convection at 30°C. (a) Determine and compare the maximum temperatures for k = 25, k = 50, k = 200 and k = 410 W/mK assuming h = 250 W/m2K. (b) Determine and compare the maximum temperature for h = 50, 250, 500 and 1000 W/m2K with k = 25 W/mK.
Problem Wall with Strip Heater The air inside a chamber is measured to be 50C and used to convectively heat a wall (h 20 w/m2 K). The wall (thermal conductivity of 4 W/m K) is 200 mm thick and has a uniform heat generation of 1000 W/m2. To prevent any heat generated within the wall from being lost to the outside of the chamber a very thin electrical strip heater is placed on the outer wall to provide a uniform...
A plane wall of thickness 2L= 30 mm and thermal conductivity k= 3 W/m·K experiences uniform volumetric heat generation at a rate q˙, while convection heat transfer occurs at both of its surfaces (x=-L, +L), each of which is exposed to a fluid of temperature ∞T∞= 20°C. Under steady-state conditions, the temperature distribution in the wall is of the form T(x)=a+bx+cx2 where a= 82.0°C, b= -210°C/m, c= -2 × 104°C/m2, and x is in meters. The origin of the x-coordinate...
The heat generation rate in a plane wall of 0.24 m thickness is 0.4 MW/m^3. The wall is exposed on both sides to convection at 30°C. a) Determine and compare the maximum temperatures for k=25, k=50, k=200 and k= 410 W/mK assuming h=250W/m^2 K. b) Determine and compare the maximum temperatures for h=50, 250, 500 and 1000 W/m^2K with k =W/mK