Lesson 2 Flashcards
is the process of cooling to provide human comfort
Air conditioning
is used for food preservation; removing heat
from substances in chemical, petroleum, and petrochemical plants; and numerous
special applications such as those in the manufacturing and construction industries
Refrigeration (Industrial refrigeration)
Is a branch of science that deals with the process of reducing and maintaining the
temperature of space or material below the temperature of the surroundings.
REFRIGERATION
Is used to describe thermal systems that maintain process space or material at a temperature less than available from ambient conditions.
REFRIGERATION
APPLICATION OF REFRIGERATION SYSTEM
● Food storage and distribution
● Storage
● Distribution
● Food processing
● Chemical and Process Industries
include the manufacturers of chemicals, petroleum refiners, petrochemical plants, paper and pulp industries that require good engineering for their refrigeration.
Chemical and Process Industries
A refrigeration method of lowering and maintaining the temperature of a material or space using a literal ice (water or other substance, say dry ice).
Ice Refrigeration
A method of refrigeration using mechanical components composing a system known
as vapor compression refrigeration system.
Mechanical Refrigeration
A method of refrigeration through the use of a system or cycle known as Absorption
Refrigeration System or cycle.
Absorption Refrigeration
A method of refrigeration system using water as refrigerant; lowering and
maintaining of system temperature is attained by creation of vacuum condition
through the action of steam jet.
Steam Jet or Vacuum Refrigeration
A method of refrigeration using air as refrigeration; the system is normally called the
Air Cycle Refrigeration system.
Air Cycle Refrigeration
FOUR BASIC COMPONENTS OF REFRIGERATION
● Evaporator
● Condenser
● Expansion Valve or Capillaries
● Compressor
Are low-pressure vapor heat exchangers.
Evaporator
Located in the freezer compartment of the refrigerator
Evaporator
forms the coldest
part of the cabinet with a temperature of about -15℃
Freezer
Just below the Freezer, there is a
Chiller Tray
Are high-pressure vapor heat exchangers.
Condenser
Standard condensing temperature
55℃
The throttling devices that transport refrigerant from high-pressure condition to low pressure condition
Expansion Valve or Capillaries
Are pressure raising devices.
Compressor
Is the rate of cooling required to freeze one ton of water at 32 ℉ into ice at 32 ℉ in one day or 24 hr.
Tons of Refrigeration (TR)
Standard evaporation temperature for a
vapor-compression refrigeration system.
5°F = -15℃
Standard condensing temperature for a
vapor-compression refrigeration system.
86°F = 30℃
Is a cycle that receives heat from a colder and delivers heat to a hotter body, not in
violation of the second law, but by virtue of a work input.
Reverse Cycle
are cycles used to pump heat from low to high temperature regions, or cycles with
the objective of extracting heat from low temperature reservoirs.
Refrigeration Cycles
are devices that operate in a cycle and transfer heat from a low-temperature region to
a high-temperature region with work input to the system.
Heat Pump and Refrigeration
is a cycle with the objective of supplying heat to the high temperature reservoir.
Heat Pump
is a body with a large heat capacity such that when heat is removed or added to the reservoir, the temperature of the reservoir does not change
Thermal Reservoir
“It is impossible to construct a cycle device that will cause heat to be transferred from a
low-temperature reservoir to a high-temperature reservoir without the input of work;
CLAUSIUS STATEMENT
is a fluid used for energy exchanges in a refrigerating or heat pump system. It is the transport fluid that conveys the heat energy from the low-temperature
to high-temperature level where it can in terms of heat transfer give up its heat.
Refrigerants
is an international agreement that took effect in 1989, and the New Clean Air Act that was signed in 1990, that limit the production and regulate the use and disposal of chlorofluorocarbon (CFC) refrigerants.
Montreal Protocol
HCFC
Hydrochlorofluorocarbon
HFC
Hydrofluorocarbon
CFC
Chlorofluorocarbon
ODP
Ozone Depletion Potential
GWP
Global Warming Potential
is the ozone destroying power of a substance
measured relative to refrigerant 11
Ozone Depletion Potential
is a relative measure of the ability of a substance to cause an increase in the temperature of the atmosphere by absorbing solar and earth radiation that is relative to the effect of refrigerant 11.
Global Warming Potential
DESIRABLE THERMAL PROPERTIES OF THE REFRIGERANTS
● Convenient evaporation and condensation pressures.
● High critical and low freezing temperatures.
● High latent heat of evaporation ang high vapor specific heat.
● Low viscosity and high film heat conductivity.
SAFETY CHARACTERISTICS
● Non-flammability
● Non-toxic
● Non-irritability
It was one of the earliest refrigerants and was widely used whenever a completely nontoxic medium was needed.
Air refrigerant
It is used for aircraft refrigeration systems.
Air refrigerant
It is one of the oldest and most widely used of all the refrigerants.
Ammonia
It is a colorless and odorless gas, and is heavier than air.
Carbon Dioxide
It is a colorless liquid with a faint, sweet, nonirritating odor.
Methyl Chloride
Is a mechanical refrigeration system, which has four basic components, namely:
evaporator, compressor, condenser, and expansion valve.
VAPOR-COMPRESSION REFRIGERATION SYSTEM
