**3. A rectangular bar as shown in Fig below is connected between two walls. The bar...
A long rectangular copper bar of a cross section of 2cm by 3cm and a long cylindrical copper rod of 2.2 cm in diameter are initially at a uniform temperature of 120 °C. They are then exposed to a cooling air stream at 22 °C with a heat transfer coefficient of 180 W/m-K. Taking the properties of the copper to be k = 400 W/m-K and p-8930 kg/m', and C -0.385 kJ/kg-K, determine: a How long would it take for...
Heat conduction occurs through any material, represented here by a rectangular bar, whether window glass or walrus blubber. The temperature of the material is T2 on the left and T1 on the right, where T2 is greater than T1. The rate of heat transfer by conduction is directly proportional to the surface area A, the temperature difference T2 - T1, and the substance's conductivity k. The rate of heat transfer is inversely proportional to the thickness d. Q kA (T2-T)...
2. A thermal energy storage unit is composed of rectangular channels and is well insulated from outer surface. It encloses alternating layers and flow passages (shown using the arrows in the image below). Each layer of the storage material is an aluminum slab of width (thickness) W=0.05 m, which is at initial temperature of 25 °C. The storage unit is charged by passing a hot gas through the passages, with the gas temperature and convection coefficient assumed to have constant...
Page 6 (5) At 298 K and I bar pressure, the density of water is 0.9970 cm the coefficient of thermal expansion is 2.07x10 K and C 75 3 J m ol. If the temperature of 282 g of water is increased by calculate w. 4. AU, AH and AS (20 pts)
Question 3 (40 marks) (a) Air enters a horizontal nozzle with a velocity of 1 m/s, a pressure of 2 bar and a temperature of 350 K. At exit from nozzle, the air temperature is 450 K. The combined rate of specific heat transfers, and specific work transfers, w to the air as it passes through the nozzle is 150 kJ/kg. Assume that the air flow is steady and air can be treated as perfect gas with = 1005 J/(kg.K)....
QUESTION 4 For the convection heat transfer problem shown in the following figure, (a) write the finite element model related to cach of the four rectangular elements, (b) write the finite clement algebraic equation for the unknown nodal temperatures at Node 5, Assume that the thermal conductivity of the material is k-5 W(m.C), the convection heat transfer coefficient on the left surface is -28 W/(m C), and the internal heat generation is zero. (25 pts) Use the following sense and...
A shell and tube heat exchanger with one shell pass and two tube passes is used to heat 8.82 kg/s of fluid from 15.6 °C to 60 °C by using saturated steam at 150 kPa. The steam is condensing on the outside of the tubes with h= 15 kW/m2.K. There are 50 tubes with an outside diameter of 1.91 cm and a wall thickness of 0.211 cm. If the fouling coefficient on the inside of the tubes is 5678 W/m2.K,...
A long steel bar with a diameter of 4 cm (ρ = 7840 kg / m3 , cp = 580 J / kg ° K, k = 52 W / mK, α = 1.21x10-5 m2 / s), internal enters the 2 m long moving belt heat treatment furnace at ambient temperature of 900 ° C at 40 ° C. Since the film coefficient in the oven is 100 W / m2K, the center axis temperature of the bar at the...
265 A person is found dead at 5 p.m. in a room where temperature is 20°C. The (1 temperature of the body is measured to be 25°C when found, and the heat transfer coefficient is estimated to be 8 W/m2.K. Modelling the human body a 30 cm diameter, 1.70 m long cylinder.calculate actual time in hours) of death of the person. Take thermophysical properties of the body :k = 6.08 * W/m.K, p = 900 kg/m3,C = 4000 J/kg.K إجابت...
4- A steel strip of thickness 6-12 mm is annealed by passing it through a large fumace whose walls are maintained at a temperature Tw corresponding to that of combustion gases flowing through the fumace (Iw Tp). The stip, whose density, spcific thermal conductivity, and emissivity are 79 kg/m3, cp -640 J/kg K, k 30 W/m K and 0.7, respectively, is to be heated from 300°C to 600°C Furnace walls, Combustion gases For a unifom convection coefficient of h-100 W/m2...