Entropy Generation of an Electric Motor: Analyzing du/dt & dS/dt

Click For Summary
SUMMARY

The discussion focuses on the entropy generation of an electric motor operating under steady load conditions. The motor draws 9.7 amperes at 110 volts and delivers 0.93 kW of mechanical energy while the surrounding temperature is maintained at 300 K. The solution manual indicates that both the change in internal energy (du/dt) and the change in total entropy are set to zero, which raises questions about the conservation of energy and the expected entropy generation. The total rate of entropy generation (Sg) is a critical factor in understanding the motor's efficiency and energy loss.

PREREQUISITES
  • Understanding of thermodynamics principles, particularly entropy and energy conservation.
  • Familiarity with electric motor operation and performance metrics.
  • Knowledge of the relationship between electrical input and mechanical output in motors.
  • Basic concepts of steady-state analysis in thermodynamic systems.
NEXT STEPS
  • Research the principles of entropy generation in thermodynamic systems.
  • Study the efficiency calculations for electric motors under varying loads.
  • Learn about the implications of setting du/dt and dS/dt to zero in thermodynamic analyses.
  • Explore the relationship between electrical energy input and mechanical energy output in electric motors.
USEFUL FOR

Engineers, physicists, and students studying thermodynamics, particularly those interested in electric motor efficiency and entropy generation analysis.

wynnl
Messages
1
Reaction score
0
For the following question, the solution manual sets du/dt (change of internal energy) = 0. Moreover, it also set the change of total entropy to zero. Why is that?

An electric motor under steady load draws 9.7 amperes at 110 volts; it delivers 0.93 kW of mechanical energy. The temperature of the surroundings is 300 K. What is the total rate of entropy generation Sg ? What is its origin ?
 
Last edited:
Physics news on Phys.org
wynnl said:
For the following question, the solution manual sets du/dt (change of internal energy) = 0. Moreover, it also set the change of total entropy to zero. Why is that?

An electric motor under steady load draws 9.7 amperes at 110 volts; it delivers 0.93 kW of mechanical energy. The temperature of the surroundings is 300 K. What is the total rate of entropy generation Sg ? What is its origin ?
Energy is conserved. I would expect some entropy generation (the problem statement even asks for its amount!), however.
 

Similar threads

Engineering Electrical Machines DC Shunt Motor
  • · Replies 16 ·
Replies
16
Views
4K
Entropy Change for an Ideal Gas
  • · Replies 3 ·
Replies
3
Views
2K
Graduate What is a Capacitor: Definition, Summary & Equations
  • · Replies 1 ·
Replies
1
Views
2K