1. Idealized real-life engine Consider a heat engine that has an ideal gas (with heat capacity ratio of y and 5 degrees of freedom) as its working substance. The gas undergoes the cycle given in the figure, where processes 1-2 and 3-4 are reversible adiabatic process. What is the (a) total work done, (b) total heat absorbed, and (c) total heat released by the engine in one cycle? Compute the efficiency of the engine and express it in terms of the cut-off ratio a = and compression ration 7 =

1. Idealized real-life engine Consider a heat engine that has an ideal gas (with heat capacity ratio of y and 5 degrees of freedom) as its working substance. The gas undergoes the cycle given in the figure, where processes 1-2 and 3-4 are reversible adiabatic process. What is the (a) total work done, (b) total heat absorbed, and (c) total heat released by the engine in one cycle? Compute the efficiency of the engine and express it in terms of the cut-off ratio a = and compression ration 7 =

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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A. Rank these engines on the basis of the change in entropy of the gas during the isothermal expansion phase of the cycle. Rank from largest to smallest. To rank items as equivalent, overlap them. B. Rank these engines on the basis of the change in entropy of the gas during one complete cycle. Rank from largest to smallest. To rank items as equivalent, overlap them.
A thermal machine operates between two reservoirs at T2 = 600 K and T1 = 350 K. It receives1.00 kJ of energy from the high-temperature reservoir and performs 250 J of work. Finda. the entropy change of the universe ∆SU for this process.b. The work W that can be performed by an ideal Carnot engine operating between these tworeservoirs (and receiving the same 1.00 kJ from the high temperature reservoir).c. Show that the difference between the amounts of work done in parts (a) and (b) isT1∆SU .Comment: See that the quantity T1∆SU is an amount of energy unavailable to do work in the second part of the experiment.This is an amount of energy unavailable to perform work in the process that is irreversible!
24. The cycle shown in the PV diagram below goes from x to y to z. 50 J of heat are absorbed in the x to y step, and the y to z step is adiabatic. For the cycle, the total work done by the gas is 28 J. Determine the heat exchanged during the z to x step. pressure Y X A. 78 J added B. 78 J released C. 22 J added D. 22 J released E. 28 J added volume N
1. What is the efficiency of a Carnot engine working between 200 C and 446C? Suggest two ways in which you can decrease the efficiency of this engine. For each of the suggestions, you just made, find the temperatures of the hot reservoir and the cold reservoir to reduce the efficiency to 20%.
8. An ideal monatomic gas expands isothermally from A to B, as the graph shows. What can be said about this process? (a) The gas does no work. (b) No heat enters or leaves the gas. (c) The first law of thermo- dynamics does not apply to an isothermal process. (d) The ideal gas law is not valid during an isothermal process. (e) There is no change in the internal energy of the gas. Isotherm B Volume Pressure
What is the energy added to the gas as heat for the cycle? What is the energy leaving the gas as heat? What is the net work done by the gas?
1
1. A gas obeys the following equation of state: ap² T m³K bar mol P(vb) = RT + where a = -0.001 and b = 8 × 10-5 m³ mol Calculate the entropy change As when the gas changes from state 1 (600 K, 100 bar) to state J 2 (450 K, 20 bar). The ideal gas heat capacity for this process is Cp = 33.5 mol K
1. A certain gasoline engine has an efficiency of 31%. What would the hot reservoir temperature be for a Carnot engine having that efficiency, if it operates with a cold reservoir temperature of 210 °C? TH= ✔°C
In the figure below you see the process done by 9.0 moles of an ideal gas with adiabatic constant 1.60. What is the efficiency of this engine?
A P P₂ 2 1 Q23=O 3 P₁ V₁ V3 The closed cycle for a heat engine that uses a diatomic gas consists of the following three steps: 1 to 2 is an increase in pressure at constant volume, 2 to 3 is an adiabatic expansion, and 3 to 1 is a decrease in volume at constant pressure. Point 1 has V1 = 192 cm³, p1=118 kPa, and T1 = 287 K. Point 2 has V2 = 192 cm³, p2 = 527 kPa, and T2 = 1282 K. Point 3 has V3 = 559 cm³, p3=118 kPa, and T3 = 836 K. What is the thermal efficiency of this engine? 12.3 % 16.8 % 18.8% 20.2 % 22.8% 25.5 %
1. One mole of an ideal gas expands isothermally at T=20°C from 1.2 m³ to 2.2 m³. The gas constant is given by R=8.314 J/(mol K). (a) Calculate the work done by the gas during the isothermal expansion. Wg= (b) Calculate the heat transfered during the expansion. Q= (c) What is the change in entropy of the gas? AS J/K (c) What is the entropy change of the thermal reservoir? AS J/K gas = = reservior (d) What is the entropy change for the gas+reservior system? AS ✔J/K system Hint: For an isothermal process how is the heat transferred by an ideal gas related to work? What is the formula for work done by an ideal gas during isothermal expansion?