Analyzing a partially reversible cycle

In summary, the problem involves analyzing a partially reversible cycle consisting of a reversible isothermal process at 500 C, followed by an adiabatic process, another reversible isothermal process at 200 C, and finally another adiabatic process to close the cycle. The heat exchange with the hot reservoir is 784 kJ per cycle, and with the colder reservoir is 460 kJ per cycle. To determine if the cycle is fully-reversible, one must justify their answer. For part b, it is necessary to determine whether the cycle is an engine or a heat pump. For parts c and d, the change in entropy of the device and the change in entropy of the universe over one cycle of operation must be calculated.
  • #1
Masih
1
0
Thermodynamic: Analyzing a partially reversible cycle

Homework Statement



A cycle (which at first appears to be a Carnot cycle) consists of a reversible isothermal
process (with reversible heat exchange with a reservoir at 500 C), followed by an adiabatic
process, which is followed by another reversible isothermal process (with reversible heat
exchange with a reservoir at 200 C), and the cycle is closed with another adiabatic process.
The magnitude of heat exchanged with the hot reservoir is 784 kJ per cycle, while the
magnitude of heat exchange with the colder reservoir is 460 kJ per cycle.
a. Is this a fully-reversible cycle? You must justify your answer.
b. If it is not fully-reversible, is it an engine or a heat pump?
c. What is the change in entropy of the device over one cycle of operation?
d. Wwhat is the entropy change of the universe over one cycle of operation of the device?
e. Sketch the cycle on T,s coordinates.


Homework Equations



dS≥dQ/T

S2-S1=Q/T

The Attempt at a Solution



I got part a. of this Problem I just need some hints to get to Part b, c and d...

For part b. I know that for an Engine: Qhigh goes from high temperature reservoir to engine, the engine creates work and releases Qlow to low temperature reservoir. A heat pump takes in work and Qlow and then release Qhigh.
I have no idea how to determine whether we have an engine or a heat pump...

I don't know where to start for part c and d
 
Last edited:
Physics news on Phys.org
  • #2
. For part e. I know that the isothermal processes will be horizontal lines on the T,s coordinates, and the adiabatic processes will be curved lines. Please provide hints for parts b., c. and d. Thanks
 

Related to Analyzing a partially reversible cycle

1. What is a partially reversible cycle?

A partially reversible cycle is a thermodynamic process in which some amount of energy is lost or dissipated as heat. This means that the cycle is not completely efficient and cannot be reversed to its original state without some energy loss.

2. How is a partially reversible cycle analyzed?

A partially reversible cycle is analyzed using the laws of thermodynamics, specifically the first and second laws. The first law states that energy cannot be created or destroyed, only transferred or converted. The second law states that the total entropy of a closed system will always increase over time.

3. What are the implications of a partially reversible cycle?

The implications of a partially reversible cycle include decreased efficiency and increased energy loss. This can have negative effects on the overall performance of a system and may require additional energy input to maintain the cycle.

4. How does a partially reversible cycle differ from a reversible cycle?

A reversible cycle is a thermodynamic process in which no energy is lost or dissipated as heat. This means that the cycle is completely efficient and can be reversed to its original state without any energy loss. In contrast, a partially reversible cycle involves some energy loss and is not completely efficient.

5. What are some examples of partially reversible cycles?

Some common examples of partially reversible cycles include the Otto cycle, where energy is lost as heat during the compression and expansion of the fuel-air mixture in a car engine, and the Rankine cycle, where energy is lost as heat during the condensation and evaporation of water in a steam turbine.

Similar threads

I Efficiency of cycles bounded by two isotherms
    • Thermodynamics
Replies
2
Views
168
How many reversible thermodynamic cycles are there between two heat reservoirs?
    • Thermodynamics
Replies
12
Views
2K
I Irreversible Isochoric Process in a Cycle
    • Other Physics Topics
Replies
8
Views
2K
Engineering How Does Efficiency Impact Calculations in a Regenerative Rankine Cycle?
    • Engineering and Comp Sci Homework Help
Replies
1
Views
582
I How to know when a reversible process between end states exists?
    • Thermodynamics
Replies
12
Views
1K
Irreversible cycles, Carnot's Principle and volume-pressure diagrams
    • Thermodynamics
Replies
7
Views
1K
Proof that in Brayton reverse cycle heat is negative
    • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
I Entropy change due to heat transfer between sources
    • Thermodynamics
Replies
15
Views
1K
Entropy Generation Homework: 100kPa-500kPa, 300K-500K, 600K
    • Engineering and Comp Sci Homework Help
Replies
6
Views
2K
Do Carnot and Stirling Engines Have the Same Efficiency?
    • Thermodynamics
Replies
8
Views
12K

Hot Threads

Recent Insights

Back
Top