The data listed below are claimed for a power cycle operating between hot and cold reservoirs at 1500 K and 450 K, respectively. For each case, determine whether the cycle operates reversibly, operates irreversibly, or is impossible.
(a) QH=600 kJ, W(cycle)=300 kJ, QC=300 kJ
(b) QH=400 kJ, W(cycle)=280 kJ, QC=120 kJ
(c) QH=700 kJ, W(cycle)=300 kJ, QC=500 kJ
(d) QH=800 kJ, W(cycle)=600 kJ, QC=200 kJ
Solution
During the reversible process the heat content of the system remains constant, i.e. it is adiabatic process, then the process is also isentropic process, i.e. the entropy of the system remains constant.
The phenomenon of undergoing reversible change is also called reversibility. In actual practice the reversible process never occurs, thus it is an ideal or hypothetical process.
Therefore in above mentioned questions the change in heat are not equal to zero.So, they are not reversible process.
The irreversible process is also called the natural process because all the processes occurring in nature are irreversible processes. Therefore (a),in which exactly the work and QC shares equal amount of part of heat generated from source which violates second law.It is impossible process.
(b)and (d) these are reversible processes.
(c) is a process in which efficiency is too low.It may occurs in nature.It is also reversible process.
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The data listed below are claimed for a power cycle operating between.docx
1. The data listed below are claimed for a power cycle operating between hot and cold reservoirs at
1500 K and 450 K, respectively. For each case, determine whether the cycle operates reversibly,
operates irreversibly, or is impossible.
(a) QH=600 kJ, W(cycle)=300 kJ, QC=300 kJ
(b) QH=400 kJ, W(cycle)=280 kJ, QC=120 kJ
(c) QH=700 kJ, W(cycle)=300 kJ, QC=500 kJ
(d) QH=800 kJ, W(cycle)=600 kJ, QC=200 kJ
Solution
During the reversible process the heat content of the system remains constant, i.e. it is adiabatic
process, then the process is also isentropic process, i.e. the entropy of the system remains
constant.
The phenomenon of undergoing reversible change is also called reversibility. In actual practice
the reversible process never occurs, thus it is an ideal or hypothetical process.
Therefore in above mentioned questions the change in heat are not equal to zero.So, they are not
reversible process.
The irreversible process is also called the natural process because all the processes occurring in
nature are irreversible processes. Therefore (a),in which exactly the work and QC shares equal
amount of part of heat generated from source which violates second law.It is impossible process.
(b)and (d) these are reversible processes.
(c) is a process in which efficiency is too low.It may occurs in nature.It is also reversible process.
