Fault of Electric Cable
Energy Bands in Crystals
Gallium Arsenide Semiconductor
Atomic Energy Levels
Electric Pressure Cooker
Steam Dryness Fraction
Superheated Steam and Steam Phase Diagram
Vapour Properties Mollier Chart Heat Capacities
What is Steam Flashing?
How to Calculate Steam Consumption During Plant Start Up
Effective Steam Distribution System
What is Water Hammer?
Steam Boiler | Working principle and Types of Boiler
Methods of Firing Steam Boiler
Fire Tube Boiler | Operation and Types of Fire Tube Boiler
Water Tube Boiler | Operation and Types of Water Tube Boiler
Steam Boiler Furnace Grate Firebox Combustion Chamber of Furnace
Feed Water and Steam Circuit of Boiler
Boiler Feed Water Treatment Demineralization Reverse Osmosis Plant Deaerator
Coal Combustion Theory
Fluidized Bed Combustion | Types and Advantages of Fluidized Bed Combustion
Steam Condenser of Turbine
Jet Condenser | Low Level High Level Ejector Jet Condenser
Surface Steam Condenser
Economics of Power Generation
Cooling Tower Useful Terms and Cooling Tower Performance
Cooling Tower Material and Main Components
Power Plant Fire Protection System
Hydrant System for Power Plant Fire Protection
Medium Velocity Water Spray or MVWS System for Fire Protection
Foam Fire Protection System
Fire Detection and Alarm System
Gas Extinguishing System
Electric Power Generation
Power Plants and Types of Power Plant
Thermal Power Generation Plant or Thermal Power Station
Hydro Power Plant | Construction Working and History of Hydro power plant
Nuclear Power Station or Nuclear Power Plant
Diesel Power Station
Why Supply Frequency is 50 Hz or 60 Hz?
Economiser in Thermal Power Plant | Economiser
MHD Generation or Magneto Hydro Dynamic Power Generation
Cogeneration | Combined Heat and Power
Thermoelectric Power Generators or Seebeck Power Generation
Cost of Electrical Energy
Gas Turbine Power Plant
Solar Energy Solar Electricity
Solar Energy System | History of Solar Energy
Types of Solar Power Station
Components of a Solar Electric Generating System
What is photovoltaic effect?
Staebler Wronski Effect
Working Principle of Photovoltaic Cell or Solar Cell
Characteristics of a Solar Cell and Parameters of a Solar Cell
Solar Cell Manufacturing Technology
What is a Solar PV Module?
What is Standalone Solar Electric System?
Engineering Thermodynamics Part 1
Science of Engineering Thermodynamics Part 2
Basic Law of Conservation and First Law of Thermodynamics
Carnot Cycle and Reversed Carnot Cycle
Enthalpy Entropy and Second Law of Thermodynamics
Rankine Cycle and Regenerative Feed Heating
Rankine Cycle for Closed Feed Water Heaters and Rankine Cycle Cogeneration
Ideal Verses Actual Rankine Cycle
Rankine Cycle Efficiency Improvement Techniques
Basic Wind Energy
Wind Turbine | Working Types and History of Wind Turbine
Theory of Wind Turbine
Vapour Properties Mollier Chart Heat Capacities
- Properties of Vapour
- Enthalpy of Vaporization
- Degree of Super heat
- Mollier Chart
- Heat Capacities
Properties of VapourLiquids when heated converted into vapour. The difference physical characteristics of liquids and vapours helps in working of engines, in which phase change took place. When steam condensed to liquid water to create a partial vacuum in a piston cylinder enclosure, and thus the excess atmospheric pressure works over the low pressure and acting on the opposite face of the piston to provide the actuating force that drove the first engine successfully in the early eighteenth century.
Later with the development of the technology atmospheric pressure was replaced by steam pressure on the piston as the driving force for the work. Examples are reciprocating engines and steam turbines working of which depends upon pressurized steam. Given below is the Temperature Entropy diagram (T-S) Above figure is for a pure substance in which temperature is plotted against entropy.
- When a sub cooled liquid at state 1, having a constant pressure is heated then it results in increase in entropy, enthalpy and temperature till the liquid reached a saturated state
- Further transfer of heat at state 2, failed to increase the temeparture of the system but results in increase of enthalpy and entropy in a boiling or vaporization process. During this process the conversion of saturated liquid at state 2 to a mixture of liquid and vapour, and finally to a saturated vapour takes place at state
- The enthalpy difference between the saturation values (vapour and liquid) h3 – h2 is called the heat of vaporization or enthalpy of vaporization. At state 3, if we continued heat addition, resulting in superheating the steam to state.
- At state 4 temeparture, enthalpy and entropy further increases. As given in the earlier Chapter tittled Enthalpy Entropy and 2nd law of thermodynamics
A measure of proximity of a superheated state (state 4 in the fig) to the saturated vapour line is the degree of superheat. The difference between the superheated temperature(T4) and the saturated vapour temperature (T3), at the same pressure is the degree of superheat of steam at state 4 (T4 – T3). During the process of phase change from state 2 to state 3, the temperature and pressure give no indication of the relative quantities of liquid and vapour in the system. The quality ‘x’ at a given pressure is defined as the ratio of the mass of the liquid mixture to vapour in a saturation curve at any point. Thus the quality varies i the range from 0 for saturated liquid to 1 for saturated vapour. Since, extensive properties are directly related to mass, thus they vary with the vapour quality in the mixed region. Example, entropy varies for saturated liquid sl at state 2 to the saturated vapour entropy sv at state 3 in accordance with the following quality equation: Where, s is the entropy per unit mass The effect of quality can also be seen on the other extensive properties like enthalpy and volume. Moisture is the variable which is closely related with the quality, together moisture and quality can be expressed as a percentage. Moisture fraction M, is defined as the ratio of mass of liquid to total mass of liquid and vapour. The sum of quality and the moisture fraction of a mixture is one.
Mollier ChartThe one of the purpose of mollier chart is to determine the work done and the power of steam turbine by finding from the chart the values of enthalpy and entropy. Mollier chart comprises of:
- Constant pressure lines
- Constant temperature lines
- Entropy lines are the vertical lines used to read the entropy at the end of the line.
- Enthalpy lines are horizontal line and used to read the enthalpy at the end of the line.
Specific Heats or Heat CapacitiesThe specific heat or heat capacities at constant volume and at constant pressure are: Change in pressure has little influence on volume and internal energy in Solid and Liquids, thus Cv = Cp.
Thermally perfect gas obeys PV = RT and its internal energy, enthalpy and heat capacities are functions of temperature only A gas is said to be calorically perfect in addition it being thermally perfect, if it also has constant heat capacities i.e at low and moderate pressure and temepartures.