Thermodynamics-reversible carnot engine

Click For Summary

Discussion Overview

The discussion revolves around a homework problem involving the thermodynamics of a refrigerator used to convert liquid water at 30 degrees Celsius into ice at -18 degrees Celsius. Participants are exploring the calculations necessary to determine the minimum work required for this process, including the heat exchanges and specific heat values involved.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant questions how to find the mass of ice needed for the calculations.
  • Another participant suggests starting by calculating the heat lost by the 1 kg of water and ice in three separate steps.
  • There is a request for a detailed explanation on how to convert the liquid water to ice.
  • A participant asks for a step-by-step breakdown of how the answer of 48.2 kJ was obtained.

Areas of Agreement / Disagreement

Participants do not appear to agree on the method to solve the problem, with multiple questions and requests for clarification indicating uncertainty and differing approaches to the calculations.

Contextual Notes

Participants have not resolved how to approach the problem, and there are missing assumptions regarding the steps needed to calculate the work required by the refrigerator.

Who May Find This Useful

Students studying thermodynamics, particularly those working on problems related to refrigeration cycles and heat transfer calculations.

anisha
Messages
9
Reaction score
0

Homework Statement


a refrigerator is used to convert 1 kg of liquid water at 30 degree celsius to ice at -18 degree celsius.the refrigerator rejects heat to surroundings which are at 30 degree celsius.the specific heat values of liquid water and ice are 4.18 kj/kgk and 1.9 kj/kgk respectively and latent heat of fusion of water is 335 kj/kg.the minimum work in kj that is to be supplied to refrigerator to accomplish ice making is?

Homework Equations


efficiency= Q2/W = (T2/T1-T2)
H = mCpT
Q2=heat rejected by refrigerater
T2= temperature of ice (-18 degree celsius)
T1= temperature of surroundings

The Attempt at a Solution


don't know how to find mass of ice??the correct answer is 48.2kj
suggest me how to proceed
 
Physics news on Phys.org
anisha said:
don't know how to find mass of ice?
anisha said:
convert 1 kg of liquid water at 30 degree celsius to ice
Step 1: read the problem statement.
 
how shall i convert that,please explain in detail
 
Start as follows:
For each of 3 separate steps,
what is the heat lost by the 1kg water/ice?
 
How you got 48.2 kJ? please give answer in step by step?
 

Similar threads

Different states of a Carnot Cycle
  • · Replies 1 ·
Replies
1
Views
2K
Refrigeration: Coefficient of Performance (Carnot & Lorenz)
  • · Replies 1 ·
Replies
1
Views
4K
2 body engine, final equilibrium temperate and work produced
  • · Replies 4 ·
Replies
4
Views
2K
Thermodynamics -- total entropy generation during cooling of tank of water....
  • · Replies 1 ·
Replies
1
Views
2K
Thermodynamics - Carnot Cycle-esque question?
  • · Replies 1 ·
Replies
1
Views
2K
Thermodynamics: Designing a hydrocooling unit
  • · Replies 2 ·
Replies
2
Views
4K
Thermodynamic/Carnot efficiency
  • · Replies 1 ·
Replies
1
Views
5K
A Carnot engine between the Earth's poles and equator
  • · Replies 67 ·
3
Replies
67
Views
7K
Undergrad How Do Carnot's Efficiency Formulas for Heat Engines Align?
  • · Replies 1 ·
Replies
1
Views
2K
Thermodynamics- Refrigeration of water/ice
  • · Replies 3 ·
Replies
3
Views
5K