Problem 1 (10 pts)(a) A heat engine operates between a reservoir at 350°C, from which it absorbs 200 kJ of heat per cycle, and a reservoir at 0°C, towhich it rejects 115 kJ of heat per cycle. Determine if this engine represents a reversible, irreversible, or impossible cycle? (4 pts)(b) An insulated container of capacity 2 m³ contains 10 kg of air. Work is done on the air till its pressure increases from 500 KPato 1 MPa. Determine the change in entropy. Assume that specific heats evaluated at 300 K. (4 pts)(c) Find the maximum possible thermal efficiency for a heat engine operating between two reservoirs at 750°C and 27°C. (2 pts)

Answer (a)To determine if the heat engine represents a reversible, irreversible, or impossible…

Answered: Problem 1 (10 pts) (a) A heat engine…

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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A proposed cyclic heat engine will accept 300 J of heat from a hot reservoir at 800 K, output 250 J of work to the surroundings, and reject 50 J of heat to a cold reservoir at 300 K. According to the 2nd law of thermodynamics, which of the following statements is correct? The system is possible but irreversible. The system is impossible. The system is possible and reversible.
A closed system undergoes a cycle consisting of three process 1-2, 2-3 and 3-1. Given that Q12 = 30kJ, Q23 = 10 kJ, 1w2 = 5 kJ, 3w2 = 5 kJ and DE31 = 15 kJ, Evaluate Q31, w23, DE12 and DE23.
Water stored in a large, well-insulated storage tank at 21oC, and atmospheric pressure is being pumped at steady state from this tank by a pump at the rate of 40m3/h. The motor driving the pump supplies energy at the rate of 8.5 k.W. The water is used as a cooling medium and passes through a heat exchanger where 255 k.W of heat is added to the water. The heated water then flows to a second large, vented tank, which is 25 m above the first tank. Determine the final temperature of the water delivered to the second tank.
A reversible power cycle whose thermal efficiency is 37% receives 50 kJ by heat transfer from a hot reservoir at 300°C and rejects energy by heat transfer to a cold reservoir at temperature Tc. Determine the energy rejected, in KJ, and Tc, in °C. Determine the entropy production for the cycle, Ocycle, in kJ/K.
Problem 2 Calculate the thermal efficiency or coefficient of performance of following cycles, and determine if the cycles are reversible, irreversible, or impossible. (a) A steam power cycle that receives heat input 1000 kJ while producing a network output 550 kJ, when interacting with two thermal reservoirs at temperatures of 700°C and 20°C. (b) A refrigeration cycle that needs 10 kJ work input to remove heat of 120 kJ to cool a room when interacting with two the inside and outside temperatures are at 20°C and 45°C.
In a steady flow process, the working fluid flows at a rate of 240 kg/min. The fluid rejects 120 kJ/s passing through the system. The conditions of fluid at inlet and outlet are given as : C1 = 300 m/s, p1 = 6.2 bar,u1 = 2100 kJ/kg, v1 = 0.37 m3/kg and C2 = 150 m/s, p2 = 1.3 bar, u2 = 1500 kJ/kg, v2 = 1.2 m3/kg. The suffix 1 indicates the conditions at inlet and 2 indicates at outlet of the system. Neglecting the change in potential energy, determine the power capacity of the system in MW.
A steady-state system for producing power consist of a pump, heat exchanger and a turbine. Water at 1.0 bar and 20°C (state 1) enters the adiabatic pump and leaves at 10 bar (state 2). The pump draws 110 kW of power, and the mass flow rate of water is 45 kg/s. The water leaving the pump enters a heat exchanger and heated at constant pressure to 400°C (state 3) using exhaust gases (Cp of gases = 1.1 kJ/kgK) that enters at 500°C and exits at 182°C. The steam is adiabatically expanded in a turbine having an isentropic efficiency of 0.71. The turbine exhausts (state 4) to the surroundings at 1.0 bar. What is thermal efficiency of this power production process? If the pump and turbine are reversible, would the efficiency of this system equal the maximum possible efficiency? (Answer Yes or NO and provide a short explanation.)
4. Two and one-half pounds of air actuate a cycle composed of the following processes: polytropic compression 1-2, with n = volume 3-1. The known data are: D1 = 20 psia, ti = 100°F, Qr = -1682 Btu. Determine (a) T2 nd Ts, (b) the work of the cycle using the pV plane, in Btu; (c) Qu (d) the thermal 1.5; constant pressure 2-3; constant efficiency, and (e) pn. Ans. (a) 1120°R, 4485°R; (b) 384.4 Btu; (c) 2067 Btu; (d) 18.60%: (e) 106.8 psia
Please explain each step
A four-stroke turbocharged V-16 diesel engine built by a car manufacturer company to power fast trains produces mechanical 3500 hp (2.609 MW) at 1200 rev/min. Determine the amount of work produced in kJ (a) per cylinder per mechanical cycle and (b) per cylinder per thermodynamic cycle.
A heat engine An engine that converts power from heat operating at a steady-state receives energy by heat transfer at a rate of Qu at TH = 1200 K and rejects energy by heat transfer to a cold reservoir at a rate Qc at Tc= 360 K. (i) Calculate the Carnot cycle efficiency (ii) For each of the following cases, analyze and determine whether the cycle operates reversibly, operates irreversibly, or is impossible. (a) QH = 720 kW, Qc = 144 kW (b) QH = 720 kVW, Wcycle = 360 kW, Qc = 288 kW (c) Wcycle = 714 kW, Qc = 306 kW (d) QH = 920 kW, Qc = 368 kW

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