# Basic Refrigeration and Air Conditioning Interview Question #### What is the basic difference in Vapor compression and Vapor absorption Refrigeration System ?

These two refrigeration systems are different in power consumption, COP, Mechanical parts, Performance while load variation etc.

#### Which has higher COP ? Vapor compression or Vapor absorption ? Explain .

Vapor Compression has the higher COP. Generally the COP of Vapor compression ranges from 3-4 but COP of  Vapor absorption is generally 1.   It happens because COPvc = Refrigeration Work / Compressor Work . But COPabs = Refrigeration Effect / (generator work + pump work ) .

#### Why The term relative COP is used ?

To state the ratio of actual COP to theoretical COP .

#### Classify Air-Conditioning Systems .

1. Window Type Air Conditioning System .

2 . Packed Air Conditioning System 3. Cenrtal Air Conditioning System .

## Engineering Mechanics

#### What is limiting friction ?

When an object is sliding over another frictional force is developed in the contact surface. This friction force creates a resistance. The maximum value of this frictional force is called the limiting friction.

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#### What is Center of Gravity ?

Center of Gravity or CG is the point where the whole mass of a body acts (irrespective of position of that body).

#### Locate the center of gravity of these simple geometries – Uniform rod , rectangle or parallelogram , triangle, semi circles, hemisphere, right circular solid cone .

Uniform rod : At its middle point

rectangle or parallelogram : Intersect points of its diagonals

triangle : where all the 3 medians of the triangle intersects

Semi-circle : at a distance 4r/3π from the base. (measured along the vertical radius)

hemisphere : at a distance 3r/8 from the base. (measured along the vertical radius)

right circular solid cone : h/4 from base from the vertical axis.

## Fluid Mechanics

#### How the pressure of the liquid is measured ?

The pressure of the liquid can be measured by manometers.

#### What are manometers ?

These are pressure measuring devices for liquid. To measure the pressure in a point in the liquid manometers balance the liquid column to another column or the same column of liquid.

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#### How manometers are classified ?

1. Simple manometers like : piezometer and U-tube manometer.

2. Differential manometer.

#### What are the uses of manometer  ?

Simple Manometers are used to measure 1. high pressure of liquids 2. pressure in pipes and channels 3. vacuum pressure.

Differential manometers are used for measuring pressure difference between two points in a pipe .

## Thermodynamics

#### What are the main objectives of boiler trial ?

Boiler trial helps to determine the generating capacity and thermal efficiency of the boilers. Heat balance sheet can be made by the boiler trial .

#### Name the different Thermodynamic Cycles

Otto Cycle, Diesel Cycle, Stirling Cycle, Joule or Brayton Cycle, Carnot Cycle, Ericsson Cycle etc.

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