# How Much Work is Lost in This Thermodynamics Scenario?

• matthewsyq1995
In summary, the problem involves cooling flue gas from 1100 C to 150 C and using the released heat to generate saturated steam at 100 C in a boiler. The heat capacity of the flue gas can be calculated using the equation CP/R = 3.83 + 0.000551 T, where T is in K. Water enters the boiler at 100 C and is vaporized at this temperature with a latent heat of vaporization of 2256.9 kJ/kg. The lost work of this process can be determined by finding the rate of entropy generation using the equation Sdot(g) = Sdotg(steam) + Sdotg(gas). However, the values for ΔS(gas
matthewsyq1995

## Homework Statement

A flue gas is cooled from 1100 C to 150 C and the heat is used to generate saturated steam at 100 C in a boiler. The flue gas has a heat capacity given by CP/R = 3.83 + 0.000551 T, where T is in K. Water enters the boiler at 100 C and is vaporized at this temperature. Its latent heat of vaporisation is 2256.9 kJ/kg. What is the lost work of this process

## The Attempt at a Solution

Basically i think i only need help in finding the rate of entropy generation of this qn. I believe i can finish the qn once i get that :)

I managed to equate mdot(steam) x ndot(gas) = -15.13g/mol by doing a simple energy balance
Tried to sub that into equation for summation of entropy but can't seem to solve it.
Sdot(g) = Sdotg(steam) + Sdotg(gas)
I have calculated ΔS(gas) and ΔS(steam) to be -41.835 and 6048 J/kgK but still can't seem to sub it in.Appreciate the help! Thks!

Last edited by a moderator:
Using the first law of thermodynamics, what do you get for the heat load?

## 1. What is thermodynamics entropy?

Thermodynamics entropy is a measure of the disorder or randomness in a system. It is a fundamental concept in thermodynamics and is defined as the amount of energy in a system that is unavailable for doing work.

## 2. How is entropy related to the second law of thermodynamics?

The second law of thermodynamics states that the total entropy of a closed system will always increase over time. This means that as energy is transferred or transformed, the entropy of the system will also increase. In other words, the second law of thermodynamics can also be thought of as the law of increasing entropy.

## 3. Can entropy be decreased or reversed?

In a closed system, the total entropy will always increase over time. However, in an open system, where energy and matter can be exchanged with the surroundings, it is possible for local decreases in entropy to occur, as long as the total entropy of the system and its surroundings increases.

## 4. How is entropy calculated?

The change in entropy of a system can be calculated using the equation ΔS = Q/T, where ΔS is the change in entropy, Q is the heat transferred, and T is the temperature in Kelvin. Entropy can also be calculated using statistical mechanics methods, but this is more complex and requires a deeper understanding of thermodynamics.

## 5. What are some real-world applications of entropy?

Entropy has numerous applications in various fields, including physics, chemistry, biology, and engineering. It is used to understand and predict the behavior of systems, such as in heat engines, chemical reactions, and biological processes. Entropy is also essential in the study of information theory and its applications in communication and data storage.

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