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1st Sem Hotel Engg. Notes

Types of Air Conditioning Plants

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Last updated: 4 July 2023

  • Centralized air–conditioning System

Unit air Conditioners

  • Window type units
  • Split-type units

Centralized Air Conditioning Plant
The central air conditioning plants or the systems are used when large buildings, hotels, theaters, airports, shopping malls, etc. are to be air-conditioned completely.
The air conditioning system operates essentially in a closed cycle.
Return air from different spaces in the property such as lodging rooms, dining areas, stores, banquet halls, kitchen, etc. comes back through the return duct is drawn by what is known as an extraction fan or exhauster.
This return air although a little stale is still cold/hot and relatively free from dirt and other contaminants present in the fresh air.
Instead of exhausting the entire return gas out and sucking in fresh air only, it is returned to the circuit to minimize energy requirement for cooling/heating and filtration.

Types of Air Conditioning Plants 1

Components of Centralised Air Conditioning Plant

  1. FRESH AIR INLET – It admits fresh air through a louver/grille situated on an outside wall very much away from the kitchen, boiler house, and water closet (WC) outlets.
  2. FILTERS – It is employed to arrest suspended particulate matter such as dirt and dust from inlet air.
  3. AIR WASHERS – This is the air – conditioning section which comprises of the pre-heater coil, refrigerating coil and banks of water sprays. The functions of air washers are to control humidity and clean air.
  4. SCRUBBER PLATES – These are a series of zigzag plates with a stream of water running down them and are used to catch the dirt-laden water droplets coming out from the water spray section in the air washer.
  5. WATER ELIMINATOR PLATES – These are a series of dry zigzag plates to remove any remaining free moisture in the air stream.
  6. MIST ELIMINATOR – It is a metallic / non-metallic bed through which air is flown upwards. Fine mist is trapped in the bed and fall down as they coalesce (combine) to bigger size.
  7. AIR HEATER –  This is composed of heating coils to bring the air up to the desirable room temperature, if necessary.
  8. INLET FAN – It is a fan for drawing air through the inlet, ducting and forcing it into the various spaces in the building.
  9. FRESH AIR INLET/LOUVERS – They are fitted in the inlet of the fresh air for uniform entry of fresh air and hence smooth mixing with return air before entry to the air – conditioning section.
  10. ROOM INLET GRILLES – One or more grilles in each room for the controlled inflow of air.
  11. ROOM EXTRACTION GRILLES – One or more grilles in each room for the outflow of air. One to discharge outside into the atmosphere and another leading back to the AC plant inlet for the re-circulation.
  12. EXTRACTION FAN – It is the fan for extracting air in the return path of the air ducting coming back from rooms and spaces.
  13. CENTRAL EXTRACTION DAMPER – In case where complete central control is exercised a part of the return air from all spaces is discharged to the atmosphere through a control damper valve in the delivery side of the extractor fan.
  14. DUCTING – Ducting is a term used to denote the passage for the flow of air from the AC plant through various passages in the building opening into the closed space to be cooled and return to the inlet ducting in the AC plant. This also includes the ducting for the exhaust to the atmosphere.

Unit Air Conditioners – Window Type AC

  • This is a completely self-contained unit with the compressor, condenser, evaporator, refrigerant piping, and air filter all assembled in a very compact manner.
  • The window AC is usually 0.5 to 5 tons incapacity.
  • The latest practice is to use sealed type compressor units so that the possibility of leakage of refrigerant is eliminated.
  • There is a provision to control the fresh air intake.
  • It is easy to install, operate and maintain.
  • Its running cost is high.
  • It requires at least one wall of the room free and open to atmosphere so that the air is discharged in the open.
Types of Air Conditioning Plants 2

 

Unit Air Conditioners –Split Type AC

In this system, the cold side of the unit ( such as expansion valve, evaporator coil) is physically separated from the hot side (compressor, condenser).
The refrigerant flows through a long pipeline connecting the hot side and the cold side.
The cold part inside the room and the hot part outside the building.
The main advantages of split type air conditioners are:
Low cost for relatively larger size units
Absence of noise as the compressor is placed outside the building.

Types of Air Conditioning Plants 3

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Syllabus BHM106

01 Maintenance

  1. Introduction
  2. Preventive and breakdown maintenance, comparisons
  3. Role & Importance of maintenance department in the hotel industry with emphasis on its relation with other departments of the hotel.
  4. Organization chart of maintenance department, duties and responsibilities of maintenance department

02 Fuels used in the catering industry

  1. Introduction
  2. Types of fuel used in catering industry; calorific value; comparative study of different fuels
  3. Calculation of amount of fuel required and cost.

03 Gas

  1. Introduction
  2. Heat terms and units; method of transfer
  3. LPG and its properties; principles of Bunsen burner, precautions to be taken while handling gas; low and high-pressure burners and their corresponding heat output
  4. Gas bank, location, different types of manifolds

04 Electricity

  1. Introduction
  2. Fundamentals of electricity, insulators, conductors, current, potential difference resistance, power, energy concepts; definitions, their units and relationships, AC and DC; single phase and three phases and its importance on equipment specifications
  3. Electric circuits, open circuits and close circuits, symbols of circuit elements, series and parallel connections, short circuits, fuses; MCB, earthing, the reason for placing switches on the live wire side.
  4. Electric wires and types of wiring
  5. Calculation of electric energy consumption of equipment, and safety precautions to be observed while using electric appliances.
  6. Types of lighting, different lighting devices, incandescent lamps, fluorescent lamps, other gas-discharged lamps, illumination, and units of illumination.
  7. External lighting
  8. Safety in handling electrical equipment

05 Water systems

  1. Introduction
  2. Water distribution system in a hotel
  3. Cold water systems in India
  4. Hardness of water, water softening, base exchange method
  5. Cold water cistern swimming pools
  6. Hot water supply system in hotels
  7. Flushing system, water taps, traps and closets.

06 Refrigeration & Air-conditioning

  1. Basic principles, latent heat, boiling point and its dependence on pressure, vapour compressor system of refrigeration and refrigerants.
  2. Vapour absorption system, care and maintenance of refrigerators, defrosting, types of refrigerant units, their care and maintenance.
  3. Conditions for comfort, relative humidity, humidification, dehumidifying, due point control, unit of air conditioning
  4. Window type air conditioner, central air conditioning, preventive maintenance
  5. Vertical transportation, elevators, escalators

07 Fire prevention and fire fighting system

  1. Classes of fire, methods of extinguishing fires (Demonstration)
  2.  Fire extinguishers, portable and stationery
  3.  Fire detectors and alarm
  4. Automatic fire detectors cum extinguishing devices
  5. Structural protection
  6. Legal requirements

08 Waste disposal and pollution control

  1. Solid and liquid waste, sullage and sewage, disposal of solid waste
  2.  Sewage treatment
  3. Pollution related to the hotel industry
  4. Water pollution, sewage pollution
  5. Air pollution, noise pollution, thermal pollution
  6. Legal Requirements

09 Safety

  1. Accident prevention
  2. Slips and falls
  3. Other safety topics

10 Security

11 Equipment replacement policy

  1. Introduction
  2. Circumstances under which equipment are replaced.
  3. Replacement policy of items which gradually deteriorates
  4. Replacement when the average annual cost is minimum
  5. Replacement when the present cost is minimum
  6. The economic replacement cycle for suddenly failing equipment

12 Audio-visual equipment

  1. Various audio-visual equipment used in hotel
  2. Care and cleaning of an overhead projector, slide projector, LCD and PowerPoint presentation units
  3. Maintenance of computers
  4. Care and cleaning of PC, CPU, Modem, UPS, Printer, Laptops
  5. Sensors – Various sensors used in different locations of a hotel – type, uses and cost-effectiveness

13 Contract maintenance

  1. Introduction
  2. The necessity of contract maintenance, advantages and disadvantages of contract maintenance
  3. Essential requirements of a contract, types of contract, their comparative advantages and disadvantages.
  4. Procedure for inviting and processing tenders, negotiating and finalizing