Uninterruptible Power Supply | UPS
Fermi Dirac Distribution Function
Fault of Electric Cable
Energy Bands in Crystals
Gallium Arsenide Semiconductor
Atomic Energy Levels
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
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?
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?
Basic Wind Energy
Wind Turbine | Working Types and History of Wind Turbine
Theory of Wind Turbine
Basic Law of Conservation and First Law of Thermodynamics
- Law of Conservation of Mass
- Law of Conservation of Energy
- Co-relation between Mass and Energy
- Co-relation between Energy and Work
- Concept about Total Energy
- First Law of Thermodynamics
Law of Conservation of MassThis law states that mass is non destructible or it can not be created or destroyed. According to this law, there exits a relationship for mass flow at different sections in a stream of flow. In the given below fig, flow passing through a pipe is given by: Steady-state-flow condition for above equation is
Law of Conservation of EnergyAs per this law “energy neither be destroyed nor be created”. Conversion of energy from ‘one form to another’ took place, whenever system changes its state. Eaxmples : in applications like:
- Potential energy (PE) changes to Kinetic energy (KE) during flow of water through pipe.
- Automobile K.E changes to heat energy during breaking of automobile on account of friction.
- Conversion of Electrical energy to heat, in the event of current flow through a resistor.
Relation between Mass and EnergyAs per Einstein’s theory of relativity about mass and energy; it is clear that Mass and Energy are convertible.
Relation Betweem Energy and WorkNewton’s second law of motion provides the concept of Work, KE and PE Assume, if the body moves then its initial and final position and velocity shall be respectively s1, s2 and V1, V2 because of the involvement of force component F. From Newton’s second law of motion the magnitude of the force component (Fs) is associated with change in magnitude of V by Above Eq can be re-arranged as In the above ds/dt is velocity (V) and integrating the equation for initial and final position ( s1 and s2) Integrating the above equation on both gives Left-side of the above equation can be equated to The Quantity is the Kinetic Energy (KE) of the body and is a scalar quantity & extensive property and change in Kinetic energy is given by Unit of KE and work are same i.e N-m or J or KJ
Similarly gravitational Potential Energy (PE) of the body is mgh and is a scalar quantity and change in Potential energy is given by It is a extensive property. Unit of PE is same as that of work i.e N-m or J or KJ. Where h is the elevation of the body with respect to earth surface.
Product of -force (F) and displacement(ds) is known as work and also be equated to change in Kinetic Energy of the body. Unit is N-m. Power(P) is rate of transfer of energy by work and can be equated Force(F) X velocity(V). OR Rate-of-doing work.
Total Energy ConceptTotal-Energy of the system engulf Kinetic Energy (KE), Potential Energy (PE) and miscellaneous energy. Examples are given as:
- when the spring is compressed. In this case energy is stored within the spring.
- Increase in stored energy is the example of total-energy during battery charging processes.
Energy Transfer by HeatSo far we have discussed only those interactions between system and surrounding that are related with work. But it is also possible for a closed system to interact with the surrounding that can’t be called as work. Example : when gas come in contact with the hot surface of a plate in a cylinder, then gas energy increases although no work has performed. This process is called energy transfer by heat. (Q) is the amount of energy transferred across the boundary of a system. Then Q into a system is considered as positive, while Q out of the system is considered as negative. Q > 0 (considered as positive) ⇒ Heat transfer to the system Q < 0 (considered as negative) ⇒ Heat transfer from the system
The heat-transfer not just depends on the end-state, but depends on the particular process. Similarly heat also not depends on the end-state. The value of heat-transfer (Q) depends on the specific process and not just on just end states. The amount of energy transfer by heat in a process is given by integral of: Where limits means from state 1 to state 2 and do not refer to the values of heat at those states. The sign notation used for heat transfer (Q) is opposite to that of work transfer (W). A Positive value of work (W) implies transfer of energy from system to surroundings and vice versa.
First Law of Thermodynamics or Energy Balance in a Closed SystemTransfer of energy by work (W) or by heat (Q) is the only way by which energy with in the closed system can be changed. Under lined principle is Energy is Conserved. When energy (heat and work) crosses the boundary in a system, then Internal-energy (U) of the system get change and this phenomenon is called First law of Thermodynamics. [Energy Change with in the system during some time interval] = [Net energy transferred in the system boundary by heat transfer process during the same interval] - [Net energy transferred out of the system boundary by work during the same interval]
In the above equation the system energy increases or decreases by an amount equal to the net-energy transferred across the boundary and can be expressed as:
|Total Energy (E2 – E1) or Δ E||Q - W|
|Δ KE + Δ PE + Δ U||Q - W|
|Energy balance in differential form (dE) Where dE is property||δQ – δW heat and work are not property|
|dE/dt||[δQ /dt – δW/dt]|
In above equation energy transfer across boundary results in change in one or more macroscopic form of energy like KE, PE and Internal energy (U). Energy balance with respect to time is expressed as: [Time rate of change of energy contained with in the system at time t] = [Net rate at which energy is being transferred in through heat transfer at time t] - [Net rate at which energy is being transferred out through work at time t] Since the time rate of change of energy is given by, Therefore,
|dE/dt||[δQ /dt – δW/dt]|
|[dKE/dt + dPE/dt + dU/dt]||[δQ /dt – δW/dt]|