Thermodynamics- carnot engine power

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SUMMARY

The discussion centers on calculating the mechanical power required for a reversed Carnot engine used in an ice-making plant, where the engine extracts heat from a box at -5°C while ambient air is at 30°C. The problem involves determining the heat transfer for 10,000 kg of ice, utilizing equations for heat removal from water and the latent heat of fusion. The coefficient of performance (C.O.P.) for the refrigerator is also a key consideration. The ambiguity in the problem statement regarding the time frame for ice production and whether mechanical power or energy is requested is noted as a potential issue.

PREREQUISITES
  • Understanding of thermodynamic principles, specifically the Carnot cycle
  • Knowledge of heat transfer calculations, including specific heat and latent heat
  • Familiarity with the coefficient of performance (C.O.P.) for refrigeration systems
  • Basic algebra and problem-solving skills for applying thermodynamic equations
NEXT STEPS
  • Calculate the mechanical power required using the formula: Power = Work done / Time taken
  • Research the concept of coefficient of performance (C.O.P.) for refrigerators and its implications
  • Explore the implications of time on the efficiency of refrigeration cycles
  • Review the principles of heat transfer in phase changes, particularly in freezing processes
USEFUL FOR

Students studying thermodynamics, engineers designing refrigeration systems, and anyone involved in the optimization of thermal processes in ice-making applications.

emg333
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Homework Statement



An ice making plant consists of a reversed Carnot engine extracting heat from a well- insulated box. The temperature in the icebox is -5C and the temperature of ambient air is 30C. Water of an initial temp 30C is placed in the icebox and allowed to freeze and cool to -5C. If the plant makes 10,000kg of ice, what is the mechanical power required?

Homework Equations



Qwater= c(water)*m*(T2-T1)
Qfreeze= Latent heat of fusion * m
Qice= c(ice)*m*(T2-T1)

n= 1- Q2/Q1

The Attempt at a Solution



I calculated Qwater, Qfreeze, and Qice. I am not sure where to go from here
 
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Okay, so that gives you the amount of heat that is removed from the water. We need to relate that to the work done.

What is the c.o.p. (coefficient of performance) for a refrigerator?

p.s. I see a problem with the way the problem statement is worded. Does it say in how much time the 10,000 kg ice must be made? And, does it ask for mechanical power or mechanical energy?
 

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