Fluid Properties and Refrigeration Cycles Explained

 EXPERIMENT – 7 : Determination of Fuel (Fluid) Properties
Q1) What is a Fluid? Explain the types of fluids.
Fluid:
A fluid is a substance that cannot resist shear stress and continuously deforms under the action of even a small force.
Types of fluids:
Ideal fluid – Imaginary fluid having no viscosity and incompressible.
Real fluid – Actual fluids having viscosity (water, air).
Newtonian fluid – Obeys Newton’s law of viscosity (τ ∝ du/dy).
Non-Newtonian fluid – Does not obey Newton’s law (paint, blood).
Compressible fluid – Density changes with pressure (air).
Incompressible fluid – Density remains constant (water).
Q2) Define the following fluid properties
(i) Mass Density (ρ)
Mass per unit volume of a fluid.
(ii) Weight Density (γ)
Weight per unit volume of a fluid.
(iii) Specific Volume (v)
Volume occupied by unit mass of fluid.
(iv) Specific Gravity
Ratio of density of a fluid to density of water at 4°C.
(v) Relative Density
Same as specific gravity; ratio of densities of two substances.
Q3) Explain Surface Tension
Surface tension is the force per unit length acting at the liquid surface which tends to minimize the surface area.
It occurs due to cohesive forces between liquid molecules.
Unit: N/m
Q4) Explain Capillary Action in Fluid & Mercury
Capillary action:
Rise or fall of liquid in a narrow tube due to surface tension.
Water: Rises in capillary tube due to adhesion > cohesion.
Mercury: Depresses in capillary tube due to cohesion > adhesion.
Q5) Explain Vapour Pressure
Vapour pressure is the pressure exerted by vapour of a liquid when the liquid and vapour are in equilibrium at a given temperature.
If pressure falls below vapour pressure, cavitation occurs.
❄️ EXPERIMENT – 8 : Vapor Compression & Vapor Absorption Refrigeration Cycle
Q1) What is C.O.P.?
Coefficient of Performance (COP) is the ratio of refrigeration effect to work input.
For refrigerator:
Q2) What is 1 Ton of Refrigeration?
1 Ton of Refrigeration is the rate of heat removal required to freeze 1 ton of ice at 0°C in 24 hours.
Q3) Explain the components of Domestic Refrigeration
Main components:
Compressor – Compresses low-pressure refrigerant.
Condenser – Rejects heat and condenses refrigerant.
Expansion valve – Reduces pressure and temperature.
Evaporator – Absorbs heat and produces cooling.
Refrigerant – Working fluid (Freon, R134a).
Q4) Explain with neat sketch VCR and VAR System
Vapour Compression Refrigeration System (VCRS):
Uses mechanical compressor
Components: Compressor → Condenser → Expansion Valve → Evaporator
High COP
Used in refrigerators, ACs
Vapour Absorption Refrigeration System (VARS):
Compressor replaced by absorber, pump & generator
Uses heat energy instead of mechanical work
Refrigerant: Ammonia–Water
Used where waste heat is available
Difference between VCRS and VARS
VCRS
VARS
Uses compressor
Uses absorber & generator
Requires electrical power
Uses heat energy
High COP
Low COP
Simple construction
Complex system