Skip to main content

Laws of Thermodynamics

First law of thermodynamics  is regarding  conservation of energy adapted for thermodynamics system .

"It states that for an isolated system total  energy of the system is remains constant . It can be transformed from one form to another but can neither be created nor destroyed ."

* Mathematically,
                     ΔU = Q - W

"It states that the change in internal energy of the closed system is equal to the amount of heat supplied to the system minus the amount of working by the system on surrounding."

Second law of thermodynamics

It gives general principle for the direction of  heat transfer and attainable efficiencies of heat engines.

Kelvin-planck statement for Heat engines

It is impossible to extract all the heat from the hot reservoir and used into useful work , there will be certainly  heat exhausted to the surrounding .

And which limits the thermal efficiency of the heat engines or precludes the perfect heat engines .

Refrigerator  :
"It is not possible of heat to flow  from cold body to warmer body without any work done on the system for this flow."

Entropy  :
In any cyclic process Entropy of the isolated system is either increasing or remains same .

Third law of Thermodynamics
It states that for the perfect crystal entropy is zero at absolute zero kelvin temperature.

Note : The crystal should be perfect and temperature should be absolute zero kelvin otherwise there will be a thermal motion within the crystal .

Labels:

Comments

Post a Comment

Popular posts from this blog

Why Distilled water is not circulated in the pipelines ?

1.Why Distilled water is not circulated in the pipelines ? Ans. In Fwg distilled water is generated still it is not directly used in Boiler without chemical dosing even it is free from contaminants . The reason to the question is distilled water ready absorption carbon dioxide and tends to become slightly acidic which can cause corrosion . 2. What is the highest temperature at which a fuel of 60 deg Flash point should be heated to achieve a certain viscosity? Ans. Less than 20 deg of its Flash point i.e 40 deg . And the reason is near its flash point tempeature fuel starts to vaporise 3. What is the percentage water of get distillated from 100% of sea water? Ans. It is around  50% rest do formation of brine , scale of carbonates and bicarbonates .
3 comments
Read more

Difference between Attemperator and De-superheater

Attemperator are fitted in order to keep the steam temperature in the final stages of the superheater within certain desired limits . This is done for two main reasons . 1. The most important is the protection of the superheater tube material from the effects of overheating. *Mild steel superheater tubes tubes should not be subjected to steam temperatures in excess of 455℃. 2. The formation of bonded deposits on superheater tubes can be reduced if steam and gas streams within certain temperature ranges are prevented from coming into contact of each other. De-Superheater is used to reduce the temperature of a quantity of superheated steam and make it suitable for used in auxiliary services requires low temperature or saturated steam . *The reason for doing this way rather than by taking the saturated steam direct from steam drum , is to protect the superheater , these must be protected against overheating under all conditions of load by circulating steam through them . *Al...
Post a Comment
Read more