Thermodynamics question - is this right?

In summary, the conversation discusses a power plant that uses steam turbines to deliver energy at 980 MW. The steam is superheated at 625 K and deposits its unused heat in river water at 285 K. Assuming the turbine operates as an ideal Carnot engine, the average temperature increase of the downstream river water is estimated to be 6.327 degrees Celsius. The conversation also mentions the efficiency of the turbine and the amount of heat drawn from the hot reservoir and rejected to the cold reservoir.
  • #1
N_L_
33
0
Suppose a power plant delivers energy at 980 MW using steam turbines. The steam goes into the turbine superheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbine operates as an ideal Carnot engine. If the river flow rate is 37 m^3 / s, estimate the average temperature increase of the river water immediately downstream from the power plant. What is the entropy increase per kilogram of the downstream river water in J / kg * K?


What I've got so far, is this right?:

e ideal = [ Th - Tl ] / Th = [625 - 285] / 625 = .544 (don't know if this has any relevance in the question being asked)

density of water - 1000 kg / m^3

flow of 37 m^3 / s times 1000 kg / m^3 = 37,000 kg / s

980 MW = 980 MJ / s = 980000 kJ

980 MW = flow (kg/s) * heat capacity (kJ / kg / degrees Celsius) * T (degrees Celsius)

T = [980000 / (37000 * 4.186)] = 6.327 degrees Celsius ?
 
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  • #2
N_L_ said:
Suppose a power plant delivers energy at 980 MW using steam turbines. The steam goes into the turbine superheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbine operates as an ideal Carnot engine. If the river flow rate is 37 m^3 / s, estimate the average temperature increase of the river water immediately downstream from the power plant. What is the entropy increase per kilogram of the downstream river water in J / kg * K?


What I've got so far, is this right?:

e ideal = [ Th - Tl ] / Th = [625 - 285] / 625 = .544 (don't know if this has any relevance in the question being asked)

density of water - 1000 kg / m^3

flow of 37 m^3 / s times 1000 kg / m^3 = 37,000 kg / s

980 MW = 980 MJ / s = 980000 kJ

980 MW = flow (kg/s) * heat capacity (kJ / kg / degrees Celsius) * T (degrees Celsius)

T = [980000 / (37000 * 4.186)] = 6.327 degrees Celsius ?
The efficiency is .544 and the work output/unit time is 980 mW. So how much heat is drawn from the hot reservoir and how much is rejected to the cold reservoir? Use:

[tex]Q_h - Q_c = W[/tex] and

[tex]\eta = W/Q_h[/tex]

AM
 
  • #3
Thank you.
 

Related to Thermodynamics question - is this right?

1. What is thermodynamics?

Thermodynamics is a branch of physics that deals with the study of heat and its relation to other forms of energy, and how energy is transferred and transformed within a system.

2. What are the laws of thermodynamics?

The laws of thermodynamics are fundamental principles that govern the behavior of energy in a thermodynamic system. They include the first law, which states that energy cannot be created or destroyed, and the second law, which states that the total entropy of a closed system will always increase over time.

3. How does thermodynamics apply to everyday life?

Thermodynamics applies to many everyday processes, such as cooking, refrigeration, and the functioning of engines and machines. It also helps us understand the transfer of energy in natural systems, such as the water cycle and photosynthesis.

4. What is the difference between heat and temperature?

Heat and temperature are related but distinct concepts. Heat is a form of energy that is transferred from a hotter object to a cooler object, while temperature is a measure of the average kinetic energy of the particles in a substance.

5. How is thermodynamics used in engineering?

Thermodynamics is essential in engineering as it helps engineers design systems that efficiently convert and transfer energy. It is used in the design and optimization of engines, power plants, and other mechanical and electrical systems.

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