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Title: Refregeration and air conditioning system
Description: Refrigeration can be defined as a process at which cools a closed space by removing heat energy from it. And when we say removing heat energy from a space or from a body this means that there is drop in temperature so we reduce temperature from high to low .and this done by some equipment such as Air-conditioner or refrigeration, because this two equipment have same cycle for cooling and refrigeration, example about this when we cools a room at specific temperature that we want, and same thing in refrigerator.
Description: Refrigeration can be defined as a process at which cools a closed space by removing heat energy from it. And when we say removing heat energy from a space or from a body this means that there is drop in temperature so we reduce temperature from high to low .and this done by some equipment such as Air-conditioner or refrigeration, because this two equipment have same cycle for cooling and refrigeration, example about this when we cools a room at specific temperature that we want, and same thing in refrigerator.
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1
Contents
Chapter 1 :
Introduction
page 5
Types of Energy
page 8
First Law of Thermodynamics
page 10
Limitation of First law of Thermodynamics
page 13
Second Law of Thermodynamics
page 15
Chapter 2 :
Methods of Refrigeration
page 16
Introduction
page 16
Applications of Refrigeration
page 16
Applications of Nitrogen
page 17
Applications of Oxygen
page 17
Applications of Argon
page 18
Refrigeration systems
page 18
Ice Refrigeration
page 19
Evaporative Refrigeration
page 19
Chapter 3
page 21
Air Refrigeration systems
page 21
Introduction
page 21
Refrigeration Load
page 22
2
Heating Load
page 22
Concept of Heat Engine, Heat Pump, & Refrigerator
23
Heat Engine
page 23
Heat pump
page 23
Refrigerator
page 24
Air Refrigeration system
page 24
Carnot Refrigeration Cycle
page 25
Application of Aircraft system Refrigeration
page 25
External & Internal Heat Source
page 26
Methods of Air Refrigeration system
page 27
References
page 28
page
3
Preface
This a brief course was done by me Hani Tbaishat
about Refrigeration & Air Conditioning system for
Chemical & Mechanical Engineering , it was include
basis of Thermodynamic science which is the core of
Refrigeration & Air conditioning Engineering
science
...
And when we say removing
heat energy from a space or from a body this means that there is drop
in temperature so we reduce temperature from high to low
...
At begining we should remember some basic and fundamental
quantities such as :
Density, specific gravity, specific volume , mass & mass flow rate,
volume & volume flow rate, velocity and acceleration , Length, time
,current, Temperature, force & pressure, work, energy, & power,
enthalpy, specific heat, & entropy
...
And all in SI units
...
▪ Specific gravity is ratio between density of a substance to its
density in standard state , but for liquid specific gravity is ratio
between density of liquid to density of water
...
& this is vice versa with density , specific
volume=1/density
...
▪ Volume & volume flow rate :SI units for volume is Litre L,
same as mass flow rate , if unit time is in seconds then unit for
volume flow rate is L/sec
...
▪ Acceleration is a vector quantity same as velocity, its velocity
of fluid moving in unit time , acceleration unit is m/sec2
...
▪ Time can measured in min, hr , but SI units for time is sec
...
▪ Temperature is measured in kelvin
▪ Force & pressure , force is the ability to move an object with
mass in kg to accelerate it by m/sec2, while pressure is how
much force N can exerted on a unit area m2
...
▪ Enthalpy is the system energy that called internal energy U that
any fluid have + work (PV) for any fluid moving
...
▪ Entropy is randomness of particles of fluid and its unit is
kj/kg
...
Now we will discuss and make brief summary about pressure and
difference between atmospheric pressure, gauge , & absolute pressure
...
acc × height
...
Absolute pressure = atmospheric pressure + Gauge pressure
...
For each equipment that operates in refrigeration cycle has two
definitions for efficiency , first one is Coefficient of performance
( COP), & second one is Energy efficiency ratio (EER)
...
2- EER is energy efficiency ratio : its idea is same as COP , ratio
between refrigerating effect for compressor in watt to power of motor
in watt
...
The second one is outside
boundaries such as heat & work
...
▪ stored energy:
1- potential energy can be studied in two ways : microscopic &
macroscopic ways, our study on macroscopic, this potential energy is
storing inside the object or fluid in molecular configuration, and its
depend on position with relative to ground, its equal product of
gravitational force and height or distance
...
3-internal energy is the sum of kinetic energy + potential energy +
nuclear energy
...
SI unit for work is N
...
Work can be done from system to surrounding or from surrounding to
system, for example in piston cylinder device ,work can produce
from system to move piston upward, or produce into system from
surrounding to move piston downwards, and we will discuss in this
chapter the relation between work and heat & energy transfer between
system & surrounding
...
In piston cylinder device heat energy is transfer from
system to surrounding when there is work done on the system &
transfer from surrounding to system work done by the system
...
● First law of thermodynamics
First law of thermodynamics is energy conservation law and its state
that energy in any system can not be created nor be destroyed , but it
could be changed from phase to phase , examples : Heat engine,
pump, compressor , all change electrical energy to mechanical energy
...
Total energy of any system is constant, and its equal to: internal
energy + potential energy + kinetic energy
...
Note : Change in internal energy of system is equal to difference
between heat & work
...
▪ processes for ideal gases
A gas is said to undergo a process when it changing from condition to
condition or from initial state to final state , and for non flow process
is that fluid still inside boundaries not cross outside boundary, the non
flow processes are :
1- Constant volume or isochoric process ( volume=constant)
...
3- Constant temperature or isothermal process
(temperature=constant)
...
5- Polytropic process
...
1- Isochoric process (V=C): this process is done at constant
volume like rigid container, so this container volume does not
changing when physical properties such as pressure, temperature
change
...
dw = p
...
cv
...
cv
...
cv
...
2- Isobaric process (P=C) : this process is done at constant
pressure , consider piston cylinder device system, if we transfer
heat energy into the system with no change in pressure, pressure
remains constant during the process , internal energy for system
will increase, and this cause temperature rise and increase then
work done from surrounding to system to move piston upward
(frictionless)
...
dq=dw Q= ( P1
...
ln(p1/p2)
...
But here physical
prosperities pressure, temperature, volume are not constant those
are vary, in isentropic process e
Title: Refregeration and air conditioning system
Description: Refrigeration can be defined as a process at which cools a closed space by removing heat energy from it. And when we say removing heat energy from a space or from a body this means that there is drop in temperature so we reduce temperature from high to low .and this done by some equipment such as Air-conditioner or refrigeration, because this two equipment have same cycle for cooling and refrigeration, example about this when we cools a room at specific temperature that we want, and same thing in refrigerator.
Description: Refrigeration can be defined as a process at which cools a closed space by removing heat energy from it. And when we say removing heat energy from a space or from a body this means that there is drop in temperature so we reduce temperature from high to low .and this done by some equipment such as Air-conditioner or refrigeration, because this two equipment have same cycle for cooling and refrigeration, example about this when we cools a room at specific temperature that we want, and same thing in refrigerator.