0.1 kg of air as an ideal gas executes a Carnot power cycle in a piston-cylinder assembly. The cycle has a thermal efficiency of 50%. The heat transfer to the air during the isothermal expansion is 50 kJ. At the end of the isothermal expansion, the pressure is 574 kPa and the volume is 0.3 m^3. Determine:a. the maximum and minimum temperatures for the cycle (ans: TH = 600K, TC = 300 K).b. the pressure and volume at the beginning of the isothermal expansion (ans: V1 = 0.224 m3, p1 = 769 kPa).c. the work and heat transfer for each of the for processes (ans: W12 = 50 kJ, Q12 = 50 kJ, W23 = 221 kJ, Q23 = 0 kJ, W34 = -25 kJ, Q34 = -25 kJ, W41 = -221 kJ, Q41 = 0 kJ).d. Sketch the cycle on a p-v diagram.

Respuesta :

Answer:

Explanation:

Check attachment for p-v Diagram

a.)

Calculate the maximum temperature of the cycle by using ideal gas equation:

[tex]P_2V_2=mRT_2\\(574)(0.3)=(1)(0.287)T_2\\T_2=600K\\T_{max}=T_2=600K[/tex]

Calculate the minimum temperature of the cycle:

[tex]\eta_{th}=1-\frac{T_{min}}{T_{max}}\\\\\frac{50}{100}=1-\frac{T_{min}}{600}\\\\T_{min}=300K[/tex]

b.)

Calculate the volume at the beginning of the isothermal expansion by using the following expression:

[tex]Q_{in}=mP_2V_2In(\frac{V_2}{V_1})\\\\50=(1)(574)(0.3)In(\frac{0.3}{V_1})\\\\V_1=0.224m^3[/tex]

Calculate the pressure at the beginning of the isothermal expansion by using the following expression:

[tex]\frac{P_1}{P_2}=\frac{V_2}{V_1}\\\\\frac{P_1}{574}=\frac{0.3}{0.224}\\\\P_1=768.75KPa=769kPa[/tex]

c.)

Process 1-2:

Heat addition for the Process 1-2 is [tex]Q_{1-2}=Q_{in}=50KJ[/tex]

Calculate the work transfer for the process 1-2:

[tex]Q_{1-2}=U_2-U_1+W_{1-2)\\50=mc_v(T_2-T_1)+W_{1-2}\\50=mc_v(T_1-T_1)+W_{1-2}\\W_{1-2}=50kJ[/tex]

Process 2-3:It is an Adiabatic Process:

Heat transfer for the Process 2-3 is [tex]Q_{2-3}=0kJ[/tex]

Calculate the work transfer for the process 2-3:

[tex]W_{2-3}=\frac{mR(T_2-T_3)}{\gamma - 1}\\\\=\frac{(1)(0.287)(600-300)}{1.4-1}\\\\W_{2-3}=215.25KJ[/tex]

Process 3-4:

Calculate the heat transfer for the process 3-4:

[tex]\eta_{th}=1-\frac{Q_{3-4}}{Q_{in}}\\\\0.5=1-\frac{Q_{3-4}}{50}\\\\Q_{3-4}=25KJ[/tex]

Calculate the work transfer for the process 3-4:

[tex]Q_{3-4}=U_4-U_3+W_{3-4)\\25=mc_v(T_4-T_3)+W_{3-4}\\25=mc_v(T_4-T_4)+W_{3-4}\\W_{3-4}=25kJ[/tex]

Process 4-1: It is an Adiabatic Process:

Heat transfer for the process 4-1 is  [tex]Q_{4-1}=0kJ[/tex]

Calculate the work transfer for the process 4-1:

[tex]W_{4-1}=\frac{mR(T_4-T_1)}{\gamma - 1}\\\\=\frac{(1)(0.287)(300-600)}{1.4-1}\\\\W_{4-1}=-215.25KJ[/tex]

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