The 150-mm-thick wall of a gas-fired furnace is constructed of fireclay brick
(a) How long does it take for the outer surface of the wall to reach a temperature of 750°C’?
(b) Plot the temperature distribution in the va1l at the foregoing lime, as well as at several intermediate times.
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Introduction to Heat Transfer
- a tray of liquid water is placed in a freezer where it cools from 20 deg C to "-5" deg C. what is the total amount of energy needed to freeze per unit of liquid water? the specific heat of ice is half of the specific heat of liquid water. the latent heat of fusion for water is 335 kj/kg include diagramarrow_forward) Stainless steel ball bearings (ρ = 8085 kg/m3and cp = 0.480 kJ/kgC) having adiameter of 1.22 cm are to be quenched in water at a rate of 1402 per minute.The balls leave the oven at a uniform temperature of 900C and are exposed to air at 300C for a while before they are dropped into the water. If thetemperature of the balls drops to 855C prior to quenching, determine:(i) The rate of heat transfer from the balls to the air; and(ii) The rate of entropy generation due to heat loss from the balls to the air.arrow_forwardHow much natural gas do you need to burn to heat twenty liters of water from 0 degrees C to 30 degrees C? and Calculate the amount of thermal energy required to raise the temperature of 80 liters of water from 20° C to 40° C. same formula?? and how do you do it?arrow_forward
- A dead body was found within a closed room of a house where the temperature was a constant 70°F. At the time of discovery, the core temperature of the body was determined to be 85°F. One hour later a second measurement showed that the core temperature of the body was 80°F. Assume that the time of death corresponds t = 0 and that the core temperature at that time was 98.6°F. Determine how many hours elapsed before the body was found. (Round your answer to one decimal place.) hrarrow_forwardA piece of chromium steel of length 7.4 cm (density = 8780 kg/m³, K = 50 W/m.K, and Cp = 200 j/kg.K) with mass 1.27 kg, is rolled into a solid cylinder with the same length and heated to a temperature of 600 C and quenched in oi at 36 C. You may take the convective heat rate coefficient between the oil and the cylinder at 280 W/m².K. a) Show that the lumped capacitance system analysis is applicable by calculating the Bi Number b) Find the temperature of the cylinder after 4 min. c) Find the total energy loss during this period. The temperature of the cylinder after 4 min is: The Bi Number is: The total energy loss during this 4 min period is: Choose Choose Choosearrow_forwardA piece of chromium steel of length 7.4 cm (density = 8780 kg/m^3; k = 50 w/mK and specific heat cp = 440j/kgK with mass 1.27 kg is rolled into a solid cylinder and heated to a temperature of 600 deg C and quenched in oil at 36 deg C. Show that the lumped capacitance system analysis is applicable and find the temperature of the cylinder after 4 min. What is the total heat transfer during the period? You may take the convective heat transfer coefficient between the oil and cylinder at 280 w/m^2 k.arrow_forward
- A welding heat source is capable of transferring 160 kJ/min to the surface of a metal part. The heated area is approximately circular, and the heat intensity decreases with increasing radius as follows: 50% of the power is transferred within a circle of diameter = 0.25 cm and 75% is transferred within a concentric circle of diameter = 0.625 cm. What are the power densities in (a) the 0.25 cm diameter inner circle and (b) the 0.625 cm diameter ring that lies around the inner circle? (c) Are these power densities sufficient for melting metal?arrow_forwardAssume that there is an isolated system which has 2 compartments that are separated by a wall that is adiabatic, impermeable, and movable. The said system contains an ideal gas. One compartment has NO-0.75 gas moles and is initially held at 200K. Then, the other compartment has N2)-0.5 gas moles and is initially held at 300K. Moreover, the initial pressures are P(1)-p(2)-2 atm. Find the final volume of each compartment at equilibrium.arrow_forwardDetermine the heat absorbed, when 1 mol of carbon monoxide gas is heated from 212.4 K to 437.2 K. The relationship for the heat capacity at constant pressure in J mol-1 K-1 is Cp = a + bT + cT2, with a = 25, b = 7.0 x 10^-3, and c = -8 x 10^-7arrow_forward
- Determine the MW and specific heat ratio of a gas whose Cv=1.386 kJ/kg.K and R= 0.485 kJ/Kg.K Provide the MW.arrow_forwardSteam at 100°C is used to warm 350 g of water contained in a 300 g aluminum container. The initial temperature of the water and aluminum is 20°C and after the steam is added, the equilibrium temperature is 50°C. What mass of steam will be required to accomplish this?Specific Heat of steam = 2010 J/kg- oCSpecific Heat of water = 4186 J/kg- oCSpecific Heat of aluminum = 900 J/kg- oCLatent Heat of Fusion of ice = 3.33 x 10 5 J/kgLatent Heat of Vaporization of water = 2.26 x 10 6 J/kgarrow_forwardThe temperature of the water at the outlet of a three-way mixing valve will most likely be A. equal to the temperature of the water at the hot water inlet. B. lower than the temperature of the water at the cold water inlet. C. higher than the temperature of the water at the hot water inlet. D. higher than the temperature of the water at the cold water inlet.arrow_forward
- Refrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning