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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Introduction and Basic Concepts about Thermodynamics
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THERMODYNAMICS
Thermodynamics actually includes all aspects of energy, energy transformation and relationship among the properties of matter.
Applications of Thermodynamics:
There are many applications of thermodynamics bit some of them are :
1. Human body
2. Refrigeration system
3. Air-conditioning system
4. Aeroplanes
5. Power Plants
6. Automobiles, etc.
SYSTEM AND CONTROL VOLUME:
System is any thing which is under consideration.
Volume of system or under boundary is called control volume.
TYPES OF SYSTEM:
1. OPEN SYSTEM:
System through which mass and energy can cross the boundary is called open system.
2. CLOSE SYSTEM:
System through which energy can transfer but mass cannot cross the boundary.
3. ISOLATED SYSTEM:
System through which mass and energy cannot transfer.
PROPERTIES OF A SYSTEM :
Any characteristic of a system defines property of a system. They are divided into several types:
1. INTENSIVE PROPERTIES:
Properties which does not depend upon the size and quantity of system. For exaqmple: temperature, pressure, density, etc.
2. EXTENSIVE PROPERTIES:
Properties which does depend upon the size and quantity of system. For example: mass, volume, mole, etc.
3. SPECIFIC PROPERTIES:
It is defined as;
Extensive properties per unit mass.
For example:
1. specific volume = volume / mass
2. Specific energy = energy / mass
3. Specfic weight = weight / volume, etc.
CONTINUUM APPROACH:
Consideration of continuity of matter that there are no holes between molecules is called Continuum Approach.
Note: At high altitudes, mean free path becomes much greater so continuum approach is not applicable. For this Rare-fied Gas Flow Theory is used.
RELATIVE DENSITY or SPECIFIC GRAVITY:
Density of solids relative to standard liquid's density that is water.
Specific Gravity = S.G. = Density of substance/Density of water
STATE OF A SYSTEM:
If a system is in equilibrium, then properties give the state of a system.
EQUILIBRIUM:
It imlpies the state of balance. A system ion equilibrium rxperiences no change.
For example:
* Thermal equilibrium: No change in temperature.
*Mechanical equilibrium: No change in pressure.
*Chemical equilibrium: No change in composition.
THE STATE POSTULATE:
It states that;
The state of a simple compressible system is completely specified by two independent intensive properties.
SIMPLE COMPRESSIBLE SYSTEM:
A system in the absence of electrical, mechanical, gravitational motion and surface tension effects is called Simple Compressible System.
PROCESS AND CYCLES:
Process is defined as;
Any change that a system undergoes from one equilibrium state to another.
Cycle is defined as;
If a system returns to its initial state at the end of the process.
QAUSI-EQUILIBRIUM PROCESS OR QUASI-STATIC:
When a process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times is called Quasi-equilibrium process.
ZEROTH LAW OF THERMODYNAMICS:
It states that;
If two bodies are in thermal equilibrium with the third body then they are also in thermal equilibrium with each other.
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...
Solid Mechanics OR Mechanics of Materials OR Strength of Materials: It is the study of mechanics of body i.e. forces and their effects on deformable solids under different loading conditions. Deformable Body Mechanics: It is the study of non-rigid solid structures which deform under load. Deformation/Distortion ⇾ change of shape and size OR have some relative displacement or rotation of particles. It happens when we apply combined load. Rigid Body Motion ⇾ Translation or rotation of particles but having constant distance between particles. Since deformation occur at particular load. Below this load, every body is considered as rigid body . Types of Load: Point Load ⇾ Load apply on a single point i.e. concentrated load. Uniformly Distributed Load (UDL) ⇾ Load remains uniform throughout an area of element like beam. Varying Distributed Load (VDL) ⇾ Load varies with length with constant rate. Moment ⇾ It measures the tend...
Strain Transformation Principal Strain and stresses can occur in the same directions. Material Properties Relation (Young, bulk Rigidity Modulus) ⇼ Hooke's Law General State of Strain ⇼ Є X , Є Y , Є Z and ૪ X , ૪ Y , ૪ Z . Stress (normal or shear)/ Strain (normal or shear) ⇼ vary with element orientation. Transformation equations for Plane strain derived from: Interpretation of Experimental measurements Represent in graphical form for plane strain (Mohr's Circle). Geometry and independent of material properties. Mohr's Circle It is defined as., " A graphical method for determining normal and shear Shear stresses without using the stress transformation equations " . While considering the circle CCW ⇼ Shear strain positive upward & Normal strain positive towards right. The construction of Mohr's circle (with normal and shear stresses are known) is quite easy which include following steps: Draw a set o...
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