ENGINEERING LESSON GUIDE 18

1
INTRODUCTION TO NAVAL ENGINEERING
REFRIGERATION and AIR CONDITIONING
2
USES OF REFRIGERATION AND AC PLANTS

• Cooling of stores and cargo
• Cooling of electronic spaces and equipment
• CIC
• Radio
• Radars
• Cooling of magazines
• AC for crew comfort

3
DEFINITIONS

• Specific Heat
• Sensible Heat
• Latent Heat of Fusion
• Latent Heat of Vaporization

4
VAPOR-COMPRESSION CYCLE
5
PARTS OF THE REFRIGERATION PLANT
6
(No Transcript)
7
REFRIGERANT

• Must have the following properties
• High latent heat of vaporization
• Non-toxicity
• Desirable saturation temperature
• Stability
• Ease of leak detection
• Low cost
• Readily available
• R-12, R-114

8
RECEIVER

• Temporary storage space and surge tank for the
  sub-cooled refrigerant
• Serves as a vapor seal to prevent vapor from
  entering the expansion valve

9
(No Transcript)
10
EVAPORATOR

• Indirect heat exchanger where refrigerant absorbs
  heat from the substance to be cooled

11
(No Transcript)
12
COMPRESSOR

• Mechanical work is expended by taking the low
  pressure, low temperature vapor refrigerant and
  turning it into high pressure, high temperature
  vapor

13
CONDENSER

• An indirect heat exchanger in which the
  refrigerant rejects heat to a cooling medium such
  as air or water (fresh or sea)

14
TYPES OF AC SYSTEMS
15
REFRIGERANT CIRCULATING SYSTEM

• Similar to the vapor-compression refrigeration
  plants
• Hot, moist air from the space is drawn through a
  duct and passed over an evaporator
• Cool dry air is returned by fan

16
CHILLED WATER CIRCULATING SYSTEM

• Water is cooled in the evaporator of a
  refrigeration system and circulated throughout
  the ship
• Cooling coils located in vent ducts
• Allows for refrigeration equipment to be
  centrally located
• Good for leak isolation

17
SAFETY PRECAUTIONS

• Phosgene gas
• Created when refrigerant is exposed to high
  temperatures
• Asphyxiation Hazard
• Typically under high pressure
• Handling
• Wear goggle and gloves

18
Reading

• Reading
• Principles of Naval Engineering
• Chapter 25
• Intro to Naval Engineering
• Chapter 29, pp. 502-510
• HOME WORK HAND OUT 7