Water is being heated in a closed pan on top of a range while being stirred by a paddle wheel as shown in Figure:1. During the process, 30 kJ of heat is transferred to the water, and 5 kJ of heat is lost to the surrounding air. The paddle-wheel work amounts to (400+R) N •m. Determine the final energy of the system if its initial energy is 10 kJ. Note: 'R' is the last two digits number of your registration number. 5k. 30 kJ Figure:1

Water is being heated in a closed pan on top of a range while being stirred by a paddle wheel as shown in Figure:1. During the process, 30 kJ of heat is transferred to the water, and 5 kJ of heat is lost to the surrounding air. The paddle-wheel work amounts to (400+R) N •m. Determine the final energy of the system if its initial energy is 10 kJ. Note: 'R' is the last two digits number of your registration number. 5k. 30 kJ Figure:1

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.34P: 2.34 Show that the temperature distribution in a sphere of radius . made of a homogeneous material...

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1. A rigid tank contains a hot fluid that is cooled while being stirred by a paddle wheel. Initially, the internal energy of the fluid is 800 kJ. During the cooling process, the fluid loses 500 kJ of heat, and the paddle wheel does 100 kJ of work on the fluid. Determine the final internal energy of the fluid. Neglect the energy stored in the paddle wheel.
Water is being heated in a closed pan on top of a range while being stirred by a paddle wheel. During the process, 30 kJ of heat is transferred to the water, and 5 kJ of heat is lost to the surrounding air. The paddle-wheel work amounts to 500 N·m. Determine the final energy of the system if its initial energy is 12.5 kJ.
Water is being heated in a close pan on top of a range while being stirred by a paddle wheel. During the process, 30kj of heat are transferred to the water, and 5kj of heat is lost to the surrounding air. The paddle-wheel work amounts to 500 N*m. Determine the final energy of the system if its initial energy is 10kj.
Water is being heated in a closed pan on top of a range while being stirred by a paddle wheel. During the process, 25 kJ of heat is transferred to the water, and 3 kJ of heat is lost to the surrounding air. The paddle-wheel work amounts to 750 N-m. Determine the final energy of the system in kN-m, if its initial energy is 12 kJ.
In a piston cylinder system, the gas an initial pressure of 100 kPa and expands from 1.5 m3 to 7.5 m3 with an increase in internal energy amounting to 160 kJ. Calculate the heat gain or loss in the system given the pressure volume relation as P2V is constant, where P is in kPa and V is in m3.
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5. A 4-m x 5-m x 7-m room is heated by the radiator of a steam-heating system. The steam radiator transfers heat at a rate of 10,000 kJ/h, and a 100-W fan is used to distribute the warm air in the room. The rate of heat loss from the room is estimated to be about 5000 kJ/h. If the initial temperature of the room air is 10°C, determine gow long it will take for the air temperature to rise to 20oC. Assume constant specific heats at room temperature where CAIR = 0.768kJ/kg-K. Draw a figure or FBD that will support the problem. Explain each step by step formula.
Air at 30°C is contained in a piston-cylinder assembly, as shown in the figure. The piston has a weight of 15N and a cross-sectional area of 0.12 m2. The initial volume of air is 3.5 m3. Heat is added until the volume of the air becomes 6.5 m3. Atmospheric pressure is 100 kPa. a. Find the final air temperature. b. Determine the work done by the air on both the piston and the atmosphere. c. Find the change in the internal energy of the air in the cylinder, and the heat exchanged with the surroundings.
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The pump of a water distribution system is powered by a 15-kW electric motor whose efficiency is 90 percent. The water flow rate through the pump is 50 L/s. The diameters of the inlet and outlet pipes are the same, and the elevation difference across the pump is negligible. If the absolute pressures at the inlet and outlet of the pump are measured to be 100 kPa and 300 kPa, respectively, determine (a) the mechanical efficiency of the pump and (b) the temperature rise of water as it flows through the pump due to mechanical inefficiencies.
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