where do thet get the enthropy valvue for S2? ExampleAir at 25°C and 100kPa flows to a isothermal reversible compressor. The compressorreleases heat at a sufficient rate to the environment (also at 25°C) to ensure that the air atthe outlet of the compressor is at 25°C. The air from the compressor flows to a rigid tankof 2m³. The tank is initialy filled with air at 100kPa and 25°C. The tank releases heat ata sufficient rate to the environment to ensure that the temperature of the air in the tankalso remains on 25°C. The process continues until the pressure in the tank reaches1000kPa. Calculate the power required by the compressor. All processes are reversible.SolutionAn entropy and energy balance over the compressor alone cannot be used to solve theproblem as the value of entropy of the air at the outlet of the compressor is not constant,it changes as the outlet pressure of the compressor rises.Consider the whole system. (It is left to the reader to draw a picture.) An energy balancegives:m₁u₁ + mihi + Win = m₂u2 + QtotWhere Qtot is the heat released by the compressor and the tank. We can determine m₁and m₂ from the Ideal Gas Law and m; from a mass balance. We can read the values forenthalpy and internal energy from the tables, but it still leaves two unknowns, the workand heat transfer. However, as the process is reversible, the total entropy remains constantand the entropy at the beginning plus entropy in = entropy at the end plus entropy out:m181 + mįsi = m282 +QtotTairThe total amount of heat released can now be calculated:Qtot = 298.15(2.337 × 6.863 +21.04 × 6.863 - 23.37 x 6.202) = 4606kJThe energy balance can now be used to calculate the work required by the compressor:2805kJ.

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Air at 25°C and 100kPa flows to a isothermal reversible compressor. The compressor releases heat at a sufficient rate to the environment (also at 25°C) to ensure that the air at the outlet of the compressor is at 25°C. The air from the compressor flows to a rigid tank of 2m³. The tank is initialy filled with air at 100kPa and 25°C. The tank releases heat at a sufficient rate to the environment to ensure that the temperature of the air in the tank also remains on 25°C. The process continues until the pressure in the tank reaches 1000kPa. Calculate the power required by the compressor. All processes are reversible.

Air at 25°C and 100kPa flows to a isothermal reversible compressor. The compressor releases heat at a sufficient rate to the environment (also at 25°C) to ensure that the air at the outlet of the compressor is at 25°C. The air from the compressor flows to a rigid tank of 2m³. The tank is initialy filled with air at 100kPa and 25°C. The tank releases heat at a sufficient rate to the environment to ensure that the temperature of the air in the tank also remains on 25°C. The process continues until the pressure in the tank reaches 1000kPa. Calculate the power required by the compressor. All processes are reversible.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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