A chip that is of length
In the off-mode the chip is in thermal equilibrium with the coolant
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Fundamentals of Heat and Mass Transfer
- A mass of 300kg of oil is cooled in 1 hour from 70 celcius to 35 celcius in a cooler consisting of a bank of tubes through which hot oil passes. Cooling water circulates around the outside of the tubes. Calculate the mass of cooling water required per hour if the water temp increases by 21 degrees celcius . Specific Heat of Oil - 2.0 kJ/kg deg C Specific Heat of Water - 4.186 kJ/kg deg Carrow_forwardThe blades of a wind turbine turn a large shaft at a relatively slow speed. The rotational speed is increased by a gearbox that has an efficiency of 0.93. In turn, the gearbox output shaft drives an electric generator with an efficiency of 0.95. The cylindrical nacelle, which houses the gearbox, generator, and associated equipment, is of length L = 6 m and diameter D = 3 m. If the turbine produces P = 2.5 MW of electrical power, and the air and surroundings temperatures are T = 25 oC and Tsur = 20 oC, respectively, determine the minimum possible operating temperature inside the nacelle. The emissivity of the nacelle is 0.83, and the convective heat transfer coefficient is h = 35 W/m2 .K. The surface of the nacelle that is adjacent to the blade hub can be considered to be adiabatic, and solar irradiation may be neglected. Use Fin or N number of fins to reduce the Ts of the nacelle less than 143 oCarrow_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
- The inside of a hollow cylinder is maintained at a temperature ??, and the outside is at a lower temperature, ??. The wall of the cylinder has a thermal conductivity ?. Ignoring end effects, show that the rate of energy conduction from the inner surface to the outer surface in the radial direction is ??/?? = 2??? [?? − ??/ ln(?/?)]The passenger section of a jet airliner is in the shape of a cylindrical tube with a length of 35.0 m and an inner radius of 2.50 m. Its walls are lined with an insulating material 6.00cm in thickness and having a thermal conductivity of 4.00 × 10−5cal/s ⋅ cm ⋅ °C. A heater must maintain the interior temperature at 25.0°C while the outside temperature is −35.0°C. What power must be supplied to the heater?arrow_forwardLiquid A has a density of 0.85 kg/m3 and a specific sensible heatcapacitance (Cv) of 2.2 kJ/kgK. Liquid B has a density of 0.78 kg/m3and a specific sensible heat capacitance (Cv) of 1.8 kJ/kgK. Liquid A isat 22°C and liquid B is at 14°C. Equal volumes of both liquids are mixedtogether. What is the resulting temperature? answer is 18.6°Carrow_forwardWhat are called Maxwell’s relations and explain each term? Write the equations. Are they extremely valuable in thermodynamics?arrow_forward
- A steel pipe (outside diameter 100 mm) is covered with two layers of insulation. The inside layer, 40 mm thick, has a thermal conductivity of 0.07 W/(m K). The outside layer, 20 mm thick, has a thermal conductivity of 0.15 W/(m K). The pipe is used to convey steam at a pressure of 600 kPa. The outside temperature of insulation is 24°C. If the pipe is 10 m long, determine the following, assuming the resistance to conductive heat transfer in steel pipe and convective resistance on the steam side are negligible: a. The heat loss per hour. b. The interface temperature of insulation.arrow_forwardA thermometer is being designed for a process in which the temperature varies from 0 to 180 °C; from experience it is known that the process temperature, when it gets out of control, reaches up to 240 ° C. Considering that only the bulb is in contact with the part inside the equipment, what should be the volume of the safety vial? It is known that the bulb has a length of 1.2 cm and a diameter of 0.5 cm; the capillary has a length of 20 cm and the scale of the thermometer is -10 to 190 ° C. Consider that the coefficient of volumetric expansion for mercury is 1.82×10−4 ° C− 1arrow_forwardWhich of the following provides the basis of convection heat transfer? Group of answer choices Newton’s Law Fourier’s Law Stefan-Boltzmann Law Toricelli’s Principlearrow_forward
- The rate of heat conduction through a plane wall is proportional to the average thermal conductivity, the wall area, and the temperature difference, but is inversely proportional to the ---------------.arrow_forwardWater is to be heated from 15°C to 65°C as it flows through a 3-cm-internaldiameter 5-m-long tube . The tube is equipped with an electric resistance heater that provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat generated in the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 10 L/min, determine the power rating of the resistance heater. Also, estimate the inner surface temperature of the tube at the exit.arrow_forwardHow does the science of heat transfer differ from the science of thermodynamics? Give your answers with real-life practical examples.arrow_forward
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