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Theory of machine| part -1

Kinematics links - Every part of machine which have relative motion to another part.   → The link should be resistance body.   What is resistant body? →Under the action of force it can transfer motion and power. Kinematics links →1. Rigid links     2. Flexible links     3. Fluid links Rigid links - There is no deformation.   Ex - piston,connecting rod Flexible links - Deformation is allowed under permissible limits. Ex - Belt drive Fluid links - A fluid link is one that is deformed by having fluid in a closed vessel and the motion is transmitted through the fluid by pressure. Ex - Hydraulic press   Types of links - 1. Singular 2. Binary 3. Ternary 4. Quaternary links
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I.C. Engine diesel cycle

                               I.C ENGINE
Diesel cycle : It is a theoritical cycle used for compression ingnition or diesel engine.
→ In this cycle,the heat addition process takes place at constant pressure.
→ Hence,this cycle is also caled as 'constant pressure process'

 The following process takes places in diesel cycle -
1. Process (1 - 2) = Reversible adiabetic(isentropic)compression.
2. Process (2 - 3) = constant pressure heat addition.
3. Process (3 - 4) = Reversible adiabetic(isentropic)expansion.
4. Process (4 - 1) = Constant volume heat rejection.

PV-diagram of diesel cycle :-
         

T-S diagram :-
                     
1. In point 1,only air is taken into the cylinder or engine.
2. Process(1 -2) After air has entered the engine,it is compress isentropically [S1 - S2].
→ During the compression process volume of air decrease but there is an increase pressure & temperature of the air.
3. The fuel ignition start,fuel is added at constant pressure upto point 3.
→process(2-3) constant pressure heat addition.
4. From 3,the expansion process of air takes place which pushes the piston and get mechanical work output from the engine.
5. Hence,process(3-4) is called as reversible adiabetic or isentropic expansion process.
6. After the expansion of air,we get mechanical work,the heat which is inside the engine must be rejected. After
7. Heat rejection strats at point 4,and it get heat rejected at constant volume.point 
(4 - 1).

* Efficiency of diesel engine : 

η =1/rc ^γ-1[σ - 1/γ(σ - 1)]
* rc =compression ratio = volume before compression/volume after compression.
rc = v1/v2 always > 1.
* γ =adiabetic index = 1.4
σ = fuel cut off ratio = volume after cut off/volume before cut off.
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