Refrigeration engineering refers to the design, installation, repair, and maintenance of refrigeration equipment used to store perishable goods at low, constant temperatures. There are several main types of refrigeration systems, including mechanical compression systems, which use electrically powered compressors to move refrigerant between high and low pressures; absorption systems, which rely on heat rather than compressors; and evaporative cooling systems, which use water evaporation to lower air temperatures. Refrigeration systems work by absorbing heat during phase changes of refrigerants to cool enclosed spaces and rejecting that heat elsewhere, helping to preserve foods longer.

1. ENGR CHARLTON S. INAO
REFRIGERATION
ENGINEERING

2. What is refrigeration Engineering?
 What is refrigeratioN?
 The term refrigeration means cooling a space, substance or system to
lower and/or maintain its temperature below the ambient one (while the
removed heat is rejected at a higher temperature). In other
words, refrigeration is artificial (human-made) cooling.
 What is refrigeration engineering?
 Refrigeration engineering refers to the design, installation, repair and
maintaining of refrigeration equipment in industrial and commercial
buildings where food and other perishable goods are stored at a constant
low temperature.

3. What Are the Different Types of
Refrigeration Systems?
 Mechanical-Compression Refrigeration Systems. he most
widely used refrigeration cycle method is mechanical
compression. It has applications in both air conditioning and
commercial and industrial refrigeration.
 As the name suggests, these types of systems transfer heat
by mechanically compressing refrigerant into a low-pressure,
cold liquid and expanding it into a high-pressure, hot gas.
Refrigerants are substances that can boil at a wide range of
temperatures with the application or removal of pressure

4. Cont…..
 ike all liquids, they absorb heat when they boil into a gas and release it
when they condense back into a liquid.
 The basics of the process deal with moving the refrigerant from the low-
pressure side of the closed system to the high-pressure side. The liquid
refrigerant boils at 40°F on the low-pressure side and absorbs heat from
the warm indoor air.
 On the high-pressure side of the system, the heat travels from the 110°F
vapor refrigerant to the cooler outdoor air, and the process repeats.

5. Absorption Refrigeration.
 Heat is also transferred in absorption refrigeration systems by compressing
and expanding refrigerant.
 These systems rely on the process of absorption and heat, instead of an
electrically powered mechanical compressor, to move the refrigerant from the
low-pressure side to the high-pressure side. Unlike mechanical-compression
refrigeration systems, which typically use R-22 and R-410A for refrigerants,
absorption refrigeration systems use refrigerants that other substances are
attracted to and absorb.

6. Cont…
 For example, residential HVAC chillers often use ammonia as the
refrigerant and water as the absorbent. The water is located in a
component called the absorber, where it sucks ammonia from the low-
pressure side of the system and removes heat while absorbing it.
 A pump sends the water-ammonia solution to a generator, which boils it,
separating the ammonia from the water before sending it to the high-
pressure side.
 In addition to the process of absorption, heat is also used to move the
refrigerant throughout the system. The heat can derive from hot water,
steam, natural gas or other fuel sources]

7. Evaporative Cooling. ...
 Unlike the mechanical-compression and absorption refrigeration systems
discussed above, evaporative cooling doesn’t use the traditional
refrigeration cycle. Instead, these units, often called swamp coolers, cool
warmer outdoor air by blowing it over water-soaked pads as it enters the
home.
 The water absorbs the heat from the air and evaporates. The cooler air is
channeled into the home and the warm air out of it.
 Evaporative coolers can reduce air temperature by 15° to 40°F but are
best suited for dry climates, such as those in the southwestern U.S.
They’re also less costly to install and use about a quarter of the energy of
central air conditioners.

8. Thermoelectric Refrigeration.
 Thermoelectric refrigeration systems are unique from the three other types of
refrigeration in that no refrigerant or water is used. These systems use an
electric current and a thermocouple.
 A thermocouple is made up of two different metal wires that are united at both
ends. Insulation separates the rest of the wires from each other. When the
current is directed on the thermocouple, one end will become hot and the
other cool.
 Reversing the current’s direction has the effect of swapping the cold and hot
junctions. The hot end will typically be placed outside of the area to be cooled
with a heat sink attached to it to keep it the same temperature as the
surrounding air.
 The cold side, which is below room temperature, is placed in the area to be
cooled, attracting heat out of the air.
 This type of refrigeration is generally used for small cooling loads that can be
difficult to access, such as electronic systems.
Source : The Refrigeration School

9. What is the necessity of refrigeration
food and meat preservation ?
 The fundamental reason for having a refrigerator is to keep food cold. Cold
temperatures help food stay fresh longer. The basic idea
behind refrigeration is to slow down the activity of bacteria (which all food
contains) so that it takes longer for the bacteria to spoil the food.

10. What is a refrigeration cycle?
 The refrigeration cycle contains four major components: the compressor,
condenser, expansion device, and evaporator.
 Refrigerant remains piped between these four components and is
contained in the refrigerant loop.
 The refrigerant begins as a cool vapor and heads to the first component:
the compressor.
 The compressor constricts the refrigerant vapor, raising its pressure, and
pushes it into the coils on the outside of the refrigerator. 2. When the hot
gas in the coils meets the cooler air temperature of the kitchen, it becomes
a liquid. ... The refrigerant absorbs the heat inside the fridge, cooling down
the air

11. Refrigeration Cycle
 TThe compressor constricts the refrigerant vapor, raising its pressure, and
pushes it into the coils on the outside of the refrigerator. 2. When the hot
gas in the coils meets the cooler air temperature of the kitchen, it becomes
a liquid. ... The refrigerant absorbs the heat inside the fridge, cooling down
the air
 The compressor constricts the refrigerant vapor, raising its pressure, and
pushes it into the coils on the outside of the refrigerator. 2. When the hot
gas in the coils meets the cooler air temperature of the kitchen, it becomes
a liquid. ... The refrigerant absorbs the heat inside the fridge, cooling down
the air

12. Illustration

13. Coefficient of Performance
 The coefficient of performance or COP (sometimes CP or CoP) of a heat
pump, refrigerator or air conditioning system is a ratio of useful heating or
cooling provided to work required.[1][2] Higher COPs equate to lower operating
costs. The COP usually exceeds 1, especially in heat pumps, because,
instead of just converting work to heat (which, if 100% efficient, would be a
COP of 1), it pumps additional heat from a heat source to where the heat is
required.
 For complete systems, COP calculations should include energy consumption
of all power consuming auxiliaries. COP is highly dependent on operating
conditions, especially absolute temperature and relative temperature between
sink and system, and is often graphed or averaged against expected
conditions.[3] Performance of Absorption refrigerator chillers is typically much
lower, as they are not heat pumps relying on compression, but instead rely on
chemical reactions driven by heat.

14. What is COP

15. Equation of COP