View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge. Photoshoped pics are developed. Some pics and GIF from Google. Videos from YouTube ( Engineering Sights ).
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Cogeneration
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Cogeneration
It is defined as, "Sequential generation of two different forms of energy from a single source (generally mechanical and thermal energy, Combined Heat & Power Generation)".
For E.g.: Warm pool water with Lower Costs and Lower Emissions of Conventional powerplant.
Technical Options for Cogeneration
Cogeneration is not used by large industries.
For constant temperature heating or drying, steam is very good (since isothermal conditions can be maintained allowing saturated steam to condensed (at that temp) utilizing latent heat.
Reduction of Carbon Emissions
1. Reciprocating Engine Cogeneration Systems
It is defined as, "Utilizing one source (diesel/gas engine) to produce electricity energy converted into heat water (process heat)".
Steps:
Burning of Fuel in engine ↦ Produce heat ↦ Produce electricity ↦ engine is cooled by coolants ↦ which transfer heat contents into circulating water ↦ which is further heated in boiler.
2. Gas Turbine Cogeneration Systems
Steps:
Fuel + air ↦ Compressed + Burn in compressor ↦ hit to turbine blades (expands) ↦ which make shaft to rotate, which produce electricity ↦ remaining heat is used to heat water.
3. Steam Turbine Cogeneration Systems
It is similar to Rankine Cycle but Condenser is replaced by Process Heater (which gives process heat as per our requirement).
Additional Components ↦ process heater + pump.
Continuously bled steam in process heater.
Steps:
Fuel burn in boiler ↦ Steam produced ↦ hit turbine blades ↦ Electricity generated ↦ Steam enter process heater ↦ Exchange heat with cold chemicals.
There are two types of Steam Turbine, namely:
Back Pressure Turbine
Pass Out Turbine
Back Pressure Turbine
It is defined as, "When the exhaust steam from cogeneration of the turbine is utilized for process work".
We can modify initial steam pressure or exhaust pressure to get required steam of desired pressure and temp.
Process heater is running Above or At atmospheric pressure.
Ideally, we want 100% of heat extracted to transform steam into liquid .
Pump cannot work with 2 phase.
Pass Out Turbine
It is defined as, "The back pressure turbine through which a certain quantity of steam is continuously exhausted for the process heating at desired pressure and temp".
Process Heater ↦ has Higher Power-to-Heat ratio.
Feasibility Criteria ↦ Cost of generation, No utility present.
References:
Material from Class Lectures + Book named Power plant Engineering by P.K Nag (4th Edition) + My knowledge.
TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions. 1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small. It is given by the formula, C t = 𝛼 (T m – T o )L Where, C t = the correction for temperature, in m. 𝛼 = the coefficient of thermal expansion. T m = the mean temperature during measurement. T o = the tempe...
Projection: The term Projection is defined as: Presentation of an image or an object on a surface. The principles used to graphically represent 3-D objects and structures on 2-D media and it based on two variables: Line of Sight. Plane of Projection. Line of Sight & Plane of Projection: Line of sight is divided into 2 types: Parallel Projection Converging Projection & A plane of projection is an imaginary flat plane upon which the image created by the lines of sight is projected. Orthographic Projection: When the projectors are parallel to each other and perpendicular to the plane of projection. The lines pf sight of the observer create a view on the screen. The screen is referred to as the Plane of Projection (POP). The lines of sight are called Projection lines or projectors. Rules of Orthographic Projection: Edges that are parallel to a plane of projection appear as lines. Edges that are incl...
Diffusion It is defined as, " The transportation of one atom from one state into other state " . Used for hardening of surfaces like die parts, gear, bolt, machine element. Hardening can be done using Temperature-Heat treatment ( diffusion couple ). There are two types of diffusion: Inter-diffusion ↔ in which atoms tend to migrate from region of high concentration to low concentration . Self-diffusion ↔ in which atoms migrate within a solid. Diffusion Mechanism There can be two conditions of moving atoms Empty spaces between adjacent sites. Atoms have sufficient energy to break bond with neighbors atoms which cause lattice distortion during displacement. If we rise temperature, small fractions of atoms is capable of diffusive motion (which cause lattice distortion). Types of Diffusion 1. Vacancy Diffusion It is defined as, " interchange of an atom from a normal lattice position to the adjacent vacant lattice site " . Extent of vacancy diffusion is a function...
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