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A family enters a winter vacation cabin has been unheated for such a long time the interior temperature is the same as the outside temperature (00C). The cabin consists of a single room of floor area 4m by 4m and height 3m. The room contains one 2kW electric heater. Assuming that the room is perfectly airtight and that all the heat from the electric heater is absorbed by the air, none escaping through the walls or being absorbed by the furnishing, how long after the heater is turned on will the temperature reach the comfort level of 240C.

Q2. An Aluminum cube 5cm side length (rho=2700,C=0.896 KJ/Kg.C and k-204 (W/m. C) initially at 20 C, two of the boundary surfaces are kept insulated, two are subjected to uniform heat flux at the rate of 10 W/m² and the remaining two surfaces dissipate heat by convection into an ambient at 20 C with heat transfer coefficient of 50 W/m² K. obtain an expression for the temperature of the cube as a function of time. and Calculate the equilibrium temperature of the cube. Assume very large k for the aluminum cube.

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Example 4.2 Two rectangles 50 by 50 cm are placed perpendicularly with a common edge. Surface one has T1=1000 K, while surface two balance with a large surrounding room at 300 K. Determine the heat lost from the surface at 1000 K to surface number 2. Room at 300 K T,- 1000 K

Q2) A plate having a thickness of 4.0 mm has an internal heat generation of 100MW/m and a thermal conductivity of 50 W/m'C. One side of the plate is insulated and the other side is maintained at 100 C. Calculate the maximum temperature in the plate.

Steady and Transient state of heat transfer by the help of an example.

3.4 Estimate the rate of heat loss due to radiation from a covered pot of water at 95 ° C. How does this compare with the 60 W that is lost due only to convection and conduction losses? What amount of energy input would be needed to maintain the water at its boiling point for 30 minutes? The polished stainless steel pot is cylindrical, 20 cm in diameter and 14 cm high, with a tight-fitting flat cover. The air temperature in the kitchen is about 25 ° C. State any assumptions you make in deriving your estimates

Answer the question shown in the image

3- A large plane wall has a thickness L=50 cm and thermal conductivity k=25 W/m.K. On the left surface (x=0), it is subjected to a uniform heat flux go, 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 surrounding temperature is 25°C. The emissivity and the convection heat transfer coefficient on the right surface are 0.7 and 15 W/m²K, respectively. (a) Derive the temperature distribution equation for the wall parametrically (based on x, T₁, qo, L, and k). Plane wall Tsurr = 25°C T% = 25°C k = 25 W/m.K h = 15 W/m²K 90 ε = 0.7 T₁ = 225°C (b) Determine the temperature of the left surface of the wall at x=0? L x

A rectangular glass window pane on a house has a width of 1.4 m, a height of 2.2 m, and a thickness of 0.49 cm. Find the energy transferred through the window by conduction in 12 hours on a day when the inside temperature of the house is 22°C and the outside temperature is 2.0°C. Take surface air layers into consideration. J

Let the cylinder (hollow) in the figure has variable heat generation which is

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Q2) The outer surfaces of the plane composite wall (A, B and C) are exposed to a fluid at 25'C and a convection heat transfer coefficient of 1000 W/m² "C. The thickness of walls A, B and C are 30, 60 and 20 mm, respectively. The thermal conductivity of walls material A, B and C are 25, 15 and 50 W/m "C, respectively. The middle wall (B) has a uniform heat generation, while there is no generation in walls A and C. The outer surfaces temperature of A and C are 132°C and 158°C, respectively. At steady state-one dimensional heat transfer conditions calculate: (1) The temperature in wall B at a distance of 10 mm from interphase of walls B and C. (2) The temperature in wall B at a distance of 5 mm from interphase of walls B and A. (3) The temperature at the middle of wall B.

11. A block of steel is uniformly heated from inside to maintain its temperature at 100 C. The block is a rectangular parallelepiped. The base of the block is a 3 cm by 3 cm square and the height of the block is 6 cm. We place this block in air at 25 C. Find the rate of heat loss from this block by natural convection. COn 11

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A radioactive sphere of 20-cm diameter generates heat at the rate of 300 W. It is cooled by placing in a cold inert fluid. The fluid temperature is –20°C. At steady state, the surface temperature of the sphere was found to be 20°C. What is the heat transfer rate from the sphere?

A vertical cylinder contains v moles of an ideal gas and is closed off by a piston of mass and area A. The acceleration due to gravity is g. The molar specific heat cy (at constant volume) of the gas is a constant independent of temperature. The heat capacities of the piston und cylinder are negligibly small and any fric- tional forees between the piston and the cylinder walls can be neglected. The whole system is thermaly insulated. Initially, the piston is clamped in position so that the gas has a volume Ve and a tomperature Tn. The pıston is now released and, after some nscillations, comes to rest in a final equilibrium situation corresponding to a larger volumc of the gas. (@) Does the temperature of the gas increase, decrease, or remain the same? (b) Does the entropy of the gas increase, decrease, or remain the same? (c) Calculate the final temperature of the gas in terms of Te, lo, unl the other parameters mentioned in the statement of the prublem.

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Calculate the amount of energy required to heat the air in a house 30 by 50 by 40 feet from 10 to 70°F. The density of air is about 0.080 lbs/ft3, and its specific heat at constant pressure is about 0.24 BTU/lb-°F. COMPLETE FBD SOLUTION AND REQUIREMENTS  PS. THIS IS A HEAT TRANSFER PROBLEM