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 ).
It is defined as, "a passage through which heat energy of steam is converted to kinetic energy by producing a high velocity jet of steam which is used to drive a steam turbine".
Nozzle ↣ Increase velocity at the expense of pressure drop.
Throat ↣ Produce steam jet with high velocity to drive steam turbine.
Types of Nozzles:
Convergent Nozzle ↣ Cross-section decreases continuously from entrance to exit.
Divergent Nozzle ↣ Cross-section increases continuously from entrance to exit.
Convergent-Divergent Nozzle ↣ Cross-section first decreases from entrance to throat, then increase from its throat to exit.
Stagnation State
For a high speed flows (in jet engines), P.e. is negligible but K.e. is not. It is convenient t combine enthalpy and K.e. of the fluid into a single term called Stagnation or Total Enthalpy.
ho = h + 0.5 V^2
Total or Stagnation State ↣ state in which flow is brought to rest isentropically in steady flow, zero adiabatic work output.
Dynamic Temperature ↣ temperature change when molecules are moving.
Velocity of Sound & Mach Number
Sound wave is defined as, "a small pressure disturbance that propagates through a states (gas, liquid, solid)".
Velocity of wave depends on properties of the medium.
Mach Number ↣ the ratio of actual velocity and the velocity of sound.
If M < 1 ↣ Subsonic Flow.
If M = 1 ↣ Sonic Flow.
If M > 1 ↣ Supersonic Flow.
Variation of Fluid Velocity with Flow Area
The last equation concludes that:
Stagnation Property Relations (Critical Pressure Ratio & Choked Flow)
Effect of Back Pressure in Convergent Nozzle
Back Pressure is defined as, "the pressure applied at the nozzle discharge region".
Condition of Flow ↣ pressure difference between inlet and outlet.
Choked Flow ↣ when nozzle operates with maximum mass flow (done by reducing back Pressure to critical pressure).
Critical Pressure ↣ pressure of fluid at a location in the nozzle where M=1 (at throat).
Rankine Cycle Rankine cycle is an ideal cycle for Vapour Power Cycles and is normally used for Electricity Generation. The Rankine cycle consist of following steps: 1 ↝ 2 : Isentropic Compression in Pump. 2 ↝ 3 : Constant Pressure Heat Addition in Boiler. 3 ↝ 4 : IsentropicExpansion in Turbine. 4 ↝ 1 : Constant Pressure Heat Rejection in Condenser. Energy Balance: Since, all the devices which Rankine Cycle posses are steady flow devices, so the energy balance for Rankine cycle is: 》For Pump ( q = 0 ): 》For Boiler ( w = 0 ): 》For Turbine ( q = 0 ): 》For condenser ( w = 0 ): The thermal efficiency of Rankine Cycle is: How can we Increase the Efficiency of A Rankine Cycle: The efficiency of a Rankine cycle can be increased: Increasing the avg. temperate at which heat is added Decreasing the avg. Temperature at which heat is rejected. The above two objectives can be achieved by following three met...
Advance High Strength Steel Conventional low carbon mild steel has simpler ferritic structure (α-iron) and good ductility. Common type of HSS is High Strength Low Alloy (HSLA) ⇥ has yield strength 550 - 690 N/sq.mm . Manganese ⇥ supporter (stabilizer) of ferrite. Conventional HSS : Is single-phase ferritic steel with a potential for some pearlite in C-Mn steel. Lower strain hardening capacity. Advance HSS : primarily steel with a microstructure containing a phase other than ferrite, pearlite, cementite. Higher strain hardening capacity. Case Study of Automobile There are three different zones in a car: Crumple Zone (Front & Back) Middle Compartment Safety Cage Some important points about these zones are: Crumple Zone ⇥ Made with those materials which absorb maximum amount of energy. Safety Cage ⇥ Multiple areas (like cabins, structural elements). Areas of Safety cage are described ahead: Cabins (Blue Areas) ⇥ Should have high streng...
Air-Standard Cycle Assumptions: The actual cycle is rather more complicated so we deduce it by considering following assumptions: The working fluid is air which continuously flow in a closed loop and act as ideal gas. All process are internally reversible . Combustion process is replaced by Heat addition process. Exhaust process is replaced by Heat rejection process. Here we are discussing 4 main cycles, namely: Otto Cycle or Constant Volume Heat Addition Cycle Diesel Cycle or Constant Pressure Heat Addition Cycle Dual Cycle Brayton Cycle 1. Otto Cycle or Constant Volume Heat Addition Cycle: The information about the diagram is given by: 1 ➤ 2: Isentropic Compression 2 ➤ 3: Constant Volume Heat Addition 3 ➤ 4: Isentropic Expansion 4 ➤ 1: Constant Volume Heat Rejection A. Efficiency of Otto Cycle: The efficiency of Otto Cycle is given by clicking the picture below: B. Work Output of Otto Cycle: The work output of ...
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