How Does the Steady Flow Energy Equation Account for Heat Transfer?

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SUMMARY

The discussion centers on the Steady Flow Energy Equation (SFEE) and its treatment of heat transfer, specifically represented as Q in the equation. The equation is expressed as mgz + 0.5mC^2 + H + Q = mgz + 0.5mC^2 + H + W, where Q denotes the net heat transfer into the system. It is clarified that Q is not present on both sides of the equation because it represents the net heat entering the control volume, which can be expressed as Q = Qin - Qout. This understanding is crucial for analyzing energy balances in thermodynamic systems.

PREREQUISITES
  • Understanding of the Steady Flow Energy Equation (SFEE)
  • Basic knowledge of thermodynamics concepts such as enthalpy (H) and work (W)
  • Familiarity with control volume analysis in thermodynamics
  • Ability to interpret energy balance equations
NEXT STEPS
  • Study the derivation and applications of the Steady Flow Energy Equation (SFEE)
  • Explore the concept of net heat transfer in thermodynamic systems
  • Learn about control volume analysis in fluid mechanics
  • Investigate the relationship between heat transfer and internal energy in thermodynamics
USEFUL FOR

This discussion is beneficial for students and professionals in thermodynamics, mechanical engineers, and anyone involved in energy systems analysis and design.

akip
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Right, I'm sure this is bread and butter to a lot of you but I have just been introduced to the SFEE.
mgz+0.5mC^2+H +Q = mgz + 0.5mC^2 +H+W

Where Q is the heat transfer, W is work done and H is enthalpy. Where is it assumed that the heat energy is in the energy balance? If heat is added where is this balanced out on the other side of the equation?
Does the heat become internal energy?

Basically I'm asking why we don't have Q on both sides?

Kip.
 
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Here is a nicely worded explanation:

http://personalpages.manchester.ac.uk/staff/john.chinn/Thermo1/SFEE1.pdf
 
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The Q in the equation is the NET heat transfer into the system (control volume). If you wish, you can represent it differently as Q = Qnet = Qin-Qout, and then rearrange so that Qin is on one side of the equation, and Qout is on the other.

Similarly, the W is the NET work output from the system (control volume) and can be represented as W = Wnet = Wout-Win.
 
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