(a)
Interpretation:
Power output of the expander and the temperature of the exhaust stream for the given set of operating conditions.
Concept Introduction:
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
Answer to Problem 7.27P
Power output of the expander: 2218.23 kW.
Temperature of exhaust stream: 1860C.
Explanation of Solution
Given Information:
An expander operates adiabatically with nitrogen. Following conditions are given:
Here,
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
To calculate power output, specific enthalpy of nitrogen will be calculated at the given inlet and exhaust pressure and temperature condition respectively. Theoretical power will be calculated equal to the difference in specific enthalpy at inlet and exhaust condition respectively. Actual power output will be calculated by dividing theoretical power by the given expander efficiency. It is to be noted that molecular weight of nitrogen is 28.
Calculation:
At
Specific entropy,
Specific enthalpy,
Exhaust pressure is 1 bar.
To have the same specific entropy, exhaust temperature,
At this exhaust temperature, enthalpy,
Negative sign implies work done by expander.
Total theoretical output power requirement = molar flow rate x theoretical power
Actual output power requirement = theoretical power / efficiency
(b)
Interpretation:
Power output of the expander and the temperature of the exhaust stream for the given set of operating conditions.
Concept Introduction:
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
Answer to Problem 7.27P
Power output of the expander: 1451.75 kW.
Temperature of exhaust stream: 157 0C.
Explanation of Solution
Given Information:
An expander operates adiabatically with nitrogen. Following conditions are given:
Here,
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
To calculate power output, specific enthalpy of nitrogen will be calculated at the given inlet and exhaust pressure and temperature condition respectively. Theoretical power will be calculated equal to the difference in specific enthalpy at inlet and exhaust condition respectively. Actual power output will be calculated by dividing theoretical power by the given expander efficiency. It is to be noted that molecular weight of nitrogen is 28.
Calculation:
At
Specific entropy,
Specific enthalpy,
Exhaust pressure is 1 bar.
To have the same specific entropy, exhaust temperature,
At this exhaust temperature, enthalpy,
Theoretical work for adiabatic expansion process,
Negative sign implies work done by expander.
Total theoretical output power requirement = molar flow rate x theoretical power
Actual output power requirement = theoretical power / efficiency
(c)
Interpretation:
Power output of the expander and the temperature of the exhaust stream for the given set of operating conditions.
Concept Introduction:
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
Answer to Problem 7.27P
Power output of the expander: 2176.73 kW.
Temperature of exhaust stream: 179 0C.
Explanation of Solution
Given Information:
An expander operates adiabatically with nitrogen. Following conditions are given:
Here,
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
To calculate power output, specific enthalpy of nitrogen will be calculated at the given inlet and exhaust pressure and temperature condition respectively. Theoretical power will be calculated equal to the difference in specific enthalpy at inlet and exhaust condition respectively. Actual power output will be calculated by dividing theoretical power by the given expander efficiency. It is to be noted that molecular weight of nitrogen is 28.
Calculation:
At
Specific entropy,
Specific enthalpy,
Exhaust pressure is 1 bar.
To have the same specific entropy, exhaust temperature,
At this exhaust temperature, enthalpy,
Theoretical work for adiabatic expansion process,
Negative sign implies work done by expander.
Total theoretical output power requirement = molar flow rate x theoretical power
Actual output power requirement = theoretical power / efficiency
(d)
Power output of the expander and the temperature of the exhaust stream for the given set of operating conditions.
Answer to Problem 7.27P
Power output of the expander: 816.51 kW.
Temperature of exhaust stream: 220 0C.
Explanation of Solution
Given Information:
An expander operates adiabatically with nitrogen. Following conditions are given:
Here,
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
To calculate power output, specific enthalpy of nitrogen will be calculated at the given inlet and exhaust pressure and temperature condition respectively. Theoretical power will be calculated equal to the difference in specific enthalpy at inlet and exhaust condition respectively. Actual power output will be calculated by dividing theoretical power by the given expander efficiency. It is to be noted that molecular weight of nitrogen is 28.
Calculation:
At
Specific entropy,
Specific enthalpy,
Exhaust pressure is 1 bar.
To have the same specific entropy, exhaust temperature,
At this exhaust temperature, enthalpy,
Theoretical work for adiabatic expansion process,
Negative sign implies work done by expander.
Total theoretical output power requirement = molar flow rate x theoretical power
Actual output power requirement = theoretical power / efficiency
(e)
Interpretation:
Power output of the expander and the temperature of the exhaust stream for the given set of operating conditions.
Concept Introduction:
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
Answer to Problem 7.27P
Power output of the expander: 1973.86 Btu/s.
Temperature of exhaust stream: 352.13 0F
Explanation of Solution
Given Information:
An expander operates adiabatically with nitrogen. Following conditions are given:
Here,
Expansion through an expander is an isentropic process which implies entropy at the inlet and exhaust will be the same. For the given inlet pressure and temperature condition, specific entropy of nitrogen will be determined. Then exhaust temperature will be determined for the given outlet pressure condition.
To calculate power output, specific enthalpy of nitrogen will be calculated at the given inlet and exhaust pressure and temperature condition respectively. Theoretical power will be calculated equal to the difference in specific enthalpy at inlet and exhaust condition respectively. Actual power output will be calculated by dividing theoretical power by the given expander efficiency. It is to be noted that molecular weight of nitrogen is 28.
Calculation:
At
Specific entropy,
Specific enthalpy,
Exhaust pressure is 15 psia.
To have the same specific entropy, exhaust temperature,
At this exhaust temperature, enthalpy,
Theoretical work for adiabatic expansion process,
Negative sign implies work done by expander.
Total theoretical output power requirement = molar flow rate x theoretical power
Actual output power requirement = theoretical power / efficiency
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