The 5-mm-thick bottom of a 200-mm-diameter panmay be made from aluminum
Want to see the full answer?
Check out a sample textbook solutionChapter 1 Solutions
Fundamentals of Heat and Mass Transfer
- A mother takes the milk to be given to her baby from the refrigerator and pours it into a cylindrical bottle for heating. The height of the milk in the bottle is 10 cm. Then he places the bottle into a large container with hot water at a temperature of 62 ° C. The heat transfer coefficient between hot water and bottle is 130 W / m2.oC. The process of heating the milk from 4 0C to 40 0C is required to be completed within 6 minutes. What should be the diameter of the bottle used? The properties of milk can be equal to the properties of water at the same temperature.arrow_forwardRequires Solution:Determine the power required providing 3 kw of colling at -10 degrees celcius while the surrounding air is at 24 degrees celcius. Answer: 0.39 kWarrow_forwardDuring a picnic on a hot summer day, the only available drinks were those at the ambient temperature of 90°F. In an effort to cool a 12-fluid-oz drink in a can, which is 5 in high and has a diameter of 2.5 in, a person grabs the can and starts shaking it in the iced water of the chest at 32°F. The temperature of the drink can be assumed to be uniform at all times, and the heat transfer coefficient between the iced water and the aluminum can is 30 Btu/h·ft2·°F. Using the properties of water for the drink, estimate how long it will take for the canned drink to cool to 40°F.arrow_forward
- Question 2 Consider a 1.5-m-high electric hot-water heater that has a diameter of 40 cm and maintains the hot water at 60 °C. The tank is located in a small room whose average temperature is 27 °C, and the heat transfer coefficients on the inner and outer surfaces of the heater are 50 and 12 W/m2⋅K, respectively. The tank is placed in another 46-cm-diameter sheet metal tank of negligible thickness, and the space between the two tanks is filled with foam insulation (k = 0.03 W/m⋅K). The thermal resistances of the water tank and the outer thin sheet metal shell are very small and can be neglected. The price of electricity is $0.08/kWh, and the homeowner pays $280 a year for water heating. Determine the fraction of the hot-water energy cost (in %) of this household that is due to the heat loss from the tank. Heat transfers through the top and bottom of the tank are negligible. In continuation of Question 2, hot-water tank insulation kits consisting of 3-cm-thick fiberglass insulation…arrow_forwardThe resistance of a copper wire used to make a motor is 0.5 Ω at 25 oC and 0.8 Ω at the motor’s operating temperature. Determine the operating temperature and the rise in temperature of the motor, given that copper has a temperature constant of 234.5 oC.arrow_forwardConsider the energy generated by a TV set. What is a suitable choice for a thermal energy reservoir?arrow_forward
- What is the ton of refrigeration required to cool 15,000 lbm of fresh pork from a temperature of 89°F to 32°F in one day? Specific heat above freezing of fresh pork is 0.68 BTU/lbm-°F.arrow_forwardIn a meat processing plant, 2-cm-thick steaks (k =0.45 W/m·K and a = 0.91 * 1027 m2/s) that are initially at25°C are to be cooled by passing them through a refrigerationroom at 211°C. The heat transfer coefficient on both sides ofthe steaks is 9 W/m2·K. If both surfaces of the steaks are to becooled to 2°C, determine how long the steaks should be keptin the refrigeration room. Solve this problem using analyticalone-term approximation method (not the Heisler charts).arrow_forwardConsider a 15-cm * 20-cm printed circuit board (PCB) that has electronic components on one side. The board is placed in a room at 20°C. The heat loss from the back surface of the board is negligible. If the circuit board is dissipating 8 W of power in steady operation, determine the average temperature of the hot surface of the board, assuming the board is (a) vertical, (b) horizontal with hot surface facing up, and (c) horizontal with hot surface facing down. Take the emissivity of the surface of the board to be 0.8 and assume the surrounding surfaces to be at the same temperature as the air in the room. Evaluate air properties at a film temperature of 32.5°C and 1 atm pressure. Is this a good assumption?arrow_forward
- In a nuclear reactor, 1-cm-diameter cylindrical uranium rods cooled by water from outside serve as the fuel. Heat is generated uniformly in the rods (k = 29.5 W/m·°C) at a rate of 7×107 W/m3. If the outer surface temperature of rods is 175 °C, determine the temperature (in °C) at their center.arrow_forwardA spherical container with an inner radius r1 = 1 m and an outer radius r2 = 1.05 m has its inner surface subjected to a uniform heat flux of q1=7kw/m^2. The outer surface of the container has a temperature T2 = 25°C, and the container wall thermal conductivity is k = 1.5 W/m·K. Show that the variation of temperature in the container wall can be expressed as and determine the temperature of the inner surface of the container at r = r1.arrow_forwardQuestion -) Consider a stainless steel spoon (k = 15 W/m·K) partially immersed in boiling water at 95°C in a kitchen at 25°C. The handle of the spoon has a cross section of 0.2cm x 1.2 cm, and extends 18 cm in the air from the free surface of the water. If the heat transfer coefficient at the exposed surfaces of the spoon handle is 15 W/m2·°C, determine the temperature difference across the exposed surface of the spoon handle. State your assumptions.arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY