Liquid Chillers

Liquid chillers are machines that removes heat from a liquid via a vapor-compression refrigeration cycle or vapor-absorption refrigeration cycle. This liquid can then be circulated through a heat exchanger to cool equipment.

centrifugal water cooled chiller

centrifugal water cooled chiller.

Liquid chillers can be of two types. They are:

  1. Shell and tube type chiller and
  2. Shell and coil type chiller.

Shell and Tube type Chiller:

  • Shell and tube type of chiller consist of a steel shell, cylindrical in shape fitted with a number of parallel tubes.
  • There can be of two types in configuration in shell and tube types of chillers, when the refrigerant flows through the tubes and the liquid to be chilled (water or brine) flows in the shell, secondly the refrigerant flows in the shell and the liquid in the tubes.
  • The latter types of chillers are called flooded type chillers are called flooded type chillers and float valve is used as the expansion device.
  • When the refrigeration flows into the shell, the level of liquid refrigerant in the shell is never full, as some clear space is required for the liquid and vapor to separate.
  • In the dry expansion type chiller, the refrigerant flows through the tube and the liquid to be chilled in the shell, so that turbulence is caused in the liquid which improves the overall heat transfer coefficient.
  • Thermostatic expansion valve is used through which the liquid refrigerant is fed into the tubes.
  • Shell and tube chillers are widely used in almost all refrigeration systems as they have very high efficiency, require negligence maintenance and are adaptable to any system.

Shell and Coil type Chiller:

  •  Shell and coil type chillers consists of a shell in which tube coils are fitted. the coils are spiral shaped. Normally dry expansion type shell and coil chillers are used. The refrigerant flows through the coils and the liquid to be chilled flows through the shell.
  • The expansion device used is thermostatic expansion valve. It is used for chilling of water for drinking purposes. In the evaporator the liquid is not recalculated and is chilled instantaneously as it passes through coils.

Classification of Welding and Allied Processes

There are different joining processes welding, brazing and soldering methods are being used in industries to join, fix metals or alloys. There are different ways of classifying the welding and allied processes.

Classification can be done on the basis of source heat, fuel, type of interaction (fusion welding or solid state welding), etc.

The general classification of welding processes and allied processes is given below

(A) Welding Processes

1. Oxy-Fuel Gas Welding Processes

  1. Air-acetylene welding
  2. Oxy-acetylene welding
  3. Oxy-hydrogen welding
  4. Pressure gas welding

2. Arc Welding Processes

  1. Carbon arc welding
  2. Shielded metal arc welding
  3. Submerged arc welding
  4. Gas Tungsten Arc Welding
  5. Gas Metal Arc Welding
  6. Plasma Arc Welding
  7. Electrogas Welding
  8. Electroslag Welding
  9. Stud arc welding
  10. Atomic hydrogen welding

3. Resistance Welding

  1. Spot welding
  2. Seam welding
  3. Projection welding
  4. Resistance butt welding
  5. Flash butt welding
  6. Percussion welding
  7. High frequency resistance welding
  8. High frequency induction welding

4. Solid-State Welding Processes

  1. Forge welding
  2. Cold pressure welding
  3. Friction welding
  4. Explosive welding
  5. Diffusion welding
  6. Cold pressure welding
  7. Thermo-compression welding

5. Thermit Welding Processes

  1. Thermit welding
  2. Pressure thermit welding

6. Radiant Energy Welding Processes

  1. Laser welding
  2. Electron beam welding


(B) Allied Processes

1. Metal Joining or Metal Depositing Processes

  1. Soldering
  2. Brazing
  3. Braze welding
  4. Adhesive bonding
  5. Metal spraying
  6. Surfacing

2. Thermal Cutting Processes

  1. Arc cutting
  2. Gas cutting