REFRIGERATION SYSTEM| (PART-1)|

Summary

In this educational video, narrator Ravi Gupta introduces the fundamental principles of refrigeration systems, focusing on the vapor compression cycle. He outlines the four main components: compressor, condenser, expansion valve, and evaporator, explaining their roles in the refrigeration process. The script delves into the system's pressure and temperature dynamics, safety devices, and the heat transfer process, all crucial for understanding the efficiency and performance of refrigeration systems.

Takeaways

• 🔧 The refrigeration system operates on the vapor compression cycle, which involves a closed loop of components.
• 🔄 The four main components of a refrigeration system are the compressor, condenser, expansion valve, and evaporator.
• 📈 The compressor's role is to raise the saturation temperature of the refrigerant, preparing it for cooling in the condenser.
• 🌡 After compression, the refrigerant's temperature increases, and it is then cooled in the condenser, changing from gas to liquid form under high pressure.
• 💧 The expansion valve is a pressure controller that reduces the pressure from high to low, facilitating the transition from liquid to gas form.
• 🔄 The system can be divided into high-pressure and low-pressure sections, with the evaporator and compressor on the low-pressure side and the condenser on the high-pressure side.
• 🛡️ Safety devices such as the master solenoid valve and dryer are integral to the system to prevent faults and maintain proper operation.
• 🌡️ The thermostatic expansion valve plays a crucial role in controlling the pressure and temperature of the refrigerant as it enters the evaporator.
• 🌡️ The evaporator extracts heat from the surroundings, cooling the area and causing the refrigerant to boil off and convert from liquid to gas.
• 🔄 The defrost element helps maintain efficient heat transfer by periodically defrosting the evaporator coil to prevent ice buildup.
• 📊 Understanding the pressure-enthalpy diagram is essential for visualizing the heat transfer and work processes within the refrigeration cycle.

Q & A

What is the basic principle that refrigeration systems work on?

Refrigeration systems work on the principle of the vapor compression cycle.

What are the four basic components of a refrigeration system?

The four basic components of a refrigeration system are the compressor, condenser, expansion valve, and evaporator.

What is the primary function of a compressor in a refrigeration system?

The primary function of a compressor is to raise the saturation temperature of the refrigerant so that it can be cooled by the condenser.

How does the condenser cool the refrigerant?

The condenser cools the refrigerant by either using sea water or fresh water, changing its vapor form into a liquid form.

What role does the expansion valve play in the refrigeration system?

The expansion valve acts as a pressure controller, converting the high-pressure refrigerant into a low-pressure refrigerant, facilitating the transition from liquid to gas form.

How does the refrigerant change from liquid to gas in the evaporator?

As the refrigerant enters the evaporator, it extracts heat from the environment, boiling off and converting from a low-pressure liquid to a gas.

What is the purpose of the high-pressure cutout in a refrigeration system?

The high-pressure cutout is a safety device that prevents the system from pressurizing excessively by cutting off the flow if the valve before the condenser is set.

What is the function of a dryer in the refrigeration system?

The dryer is used to eliminate any gas, moisture, or oil particles that might be carried over from the compressor, ensuring clean refrigerant flow.

How does a thermostatic expansion valve control the refrigerant flow?

A thermostatic expansion valve monitors the conditions inside the evaporator and adjusts the opening to control the flow of refrigerant based on the sensed temperature.

What is the purpose of the defrost element in the evaporator?

The defrost element is provided to periodically defrost the evaporator coil, preventing the unwanted accumulation of ice and ensuring efficient heat transfer.

How is the coefficient of performance (COP) of a refrigeration system determined?

The COP is determined by the ratio of the heat energy received (from the environment) to the heat energy equivalent of the work done (compression work plus heat rejected in the condenser).

Outlines

00:00

🌀 Introduction to Marine Refrigeration Systems

In this introductory paragraph, the narrator, Ravi Gupta, welcomes viewers to the Marine Engineering Hub and sets the stage for a discussion on refrigeration systems. The focus is on the vapor compression cycle, which is fundamental to refrigeration systems. Gupta outlines the four main components of a refrigeration system: the compressor, condenser, expansion valve, and evaporator. He explains that the system operates in a closed cycle, with the refrigerant vapor being compressed in the compressor, cooled in the condenser, and then expanded through the valve to evaporate and absorb heat. The paragraph also touches on the high-pressure and low-pressure zones within the system and the role of the expansion valve as a pressure controller.

05:05

🔧 Safety and Operational Components of a Refrigeration System

This paragraph delves into the operational sequence and safety features of a refrigeration system. It begins with the refrigerant vapor exiting the evaporator and entering the compressor, where it is compressed. The paragraph mentions a high-pressure cutout as a safety device to prevent over-pressurization before the condenser. The refrigerant is then cooled in the condenser, either by seawater or freshwater, and collected in a receiver unit. The liquid refrigerant passes through a master solenoid valve, a dryer to remove impurities, and a thermostatic expansion valve, which lowers the pressure and prepares the refrigerant for evaporation. The paragraph also discusses the role of the master solenoid in preventing refrigerant flow in case of compressor faults and the function of the thermostatic solenoid in regulating the flow based on evaporator temperature. Additionally, a defrost element is mentioned to maintain efficient heat transfer by preventing ice accumulation on the evaporator coil.

10:08

📊 Understanding the Vapor Compression Cycle with P-H Diagram

In the final paragraph, the focus shifts to understanding the vapor compression cycle through a pressure-enthalpy (P-H) diagram. The diagram includes lines representing absolute temperature, entropy, saturated liquid, and saturated vapor. The paragraph explains the process of compression, condensation, expansion, and evaporation within the cycle. It describes how the pressure and temperature of the refrigerant change as it moves through the system, from being compressed and cooled in the condenser to expanding and evaporating in the evaporator. The paragraph also explains the areas under the P-H diagram that represent the heat energy extracted from the environment, the work done by the compressor, and the heat rejected in the condenser. The coefficient of performance is briefly mentioned, relating to the efficiency of the refrigeration system. The paragraph concludes by encouraging viewers to ask questions if they have any doubts.

Keywords

💡Refrigeration System

A refrigeration system is a thermal device that removes heat from a low-temperature reservoir and releases it into a high-temperature reservoir. In the context of the video, it operates on the vapor compression cycle, which is fundamental to understanding how the system works. The script discusses the components and functions of a refrigeration system, highlighting its role in cooling environments by extracting heat.

💡Vapor Compression Cycle

The vapor compression cycle is the principle on which refrigeration systems operate. It involves the compression of vapor, condensation, expansion, and evaporation of the refrigerant. The script explains that this cycle is crucial for the refrigerant to absorb heat from the environment, cool it down, and then release the heat elsewhere, making it the core process in refrigeration.

💡Compressor

The compressor is a key component in a refrigeration system, responsible for increasing the pressure and temperature of the refrigerant vapor. As mentioned in the script, its primary function is to raise the saturation temperature of the refrigerant so that it can be cooled by the condenser. The compressor plays a critical role in the vapor compression cycle by compressing the refrigerant gas.

💡Condenser

The condenser is another essential part of the refrigeration system, where the high-pressure, high-temperature refrigerant gas is cooled and condensed into a liquid. The script describes how the condenser uses either seawater or freshwater to cool the refrigerant, changing its state from gas to liquid, which is a critical step in the cycle.

💡Expansion Valve

The expansion valve is a device that controls the pressure of the refrigerant, reducing it from high to low. As explained in the script, it plays a crucial role in the refrigeration system by converting the high-pressure liquid refrigerant into a low-pressure liquid, which then enters the evaporator. This pressure drop is necessary for the refrigerant to absorb heat effectively.

💡Evaporator

The evaporator is where the refrigerant absorbs heat from the environment, causing it to evaporate and turn into a gas. The script mentions that the refrigerant enters the evaporator in a low-pressure liquid state and extracts heat, which cools the surroundings and changes the refrigerant back into a gas, ready to be compressed again.

💡High Pressure System

The high pressure system in a refrigeration system refers to the part of the cycle where the refrigerant is under high pressure. The script explains that from the discharge of the compressor to the inlet of the expansion valve, the refrigerant is in a high-pressure zone, which is critical for the condensation process.

💡Low Pressure System

The low pressure system is the opposite of the high pressure system, where the refrigerant is in a low-pressure state. The script describes this as the part of the cycle from the evaporator to the compressor, where the refrigerant is in a gaseous state at low pressure, facilitating heat absorption.

💡Safety Devices

Safety devices are crucial in a refrigeration system to prevent malfunctions and ensure safe operation. The script mentions devices like the high-pressure cutout and master solenoid, which protect the system by preventing over-pressurization and controlling the flow of refrigerant in case of faults.

💡Thermostatic Expansion Valve

The thermostatic expansion valve is a type of expansion valve that controls the flow of refrigerant based on temperature. The script explains that this valve is crucial for converting the high-pressure liquid refrigerant into a low-pressure liquid, which then enters the evaporator to absorb heat and cool the environment.

💡Coefficient of Performance (COP)

The coefficient of performance is a measure of the efficiency of a refrigeration system, indicating how much heat is extracted relative to the work done. The script discusses how the COP can be understood in terms of the areas under the pressure-enthalpy graph, showing the relationship between the heat absorbed, the work done, and the heat rejected.

Highlights

Refrigeration systems operate on the principle of the vapor compression cycle.

The refrigeration system consists of four basic components: compressor, condenser, expansion valve, and evaporator.

The refrigeration cycle is a closed system with the refrigerant vapor being compressed in the compressor.

The temperature of the refrigerant increases after compression, which allows it to be cooled by the condenser.

The condenser cools the refrigerant using either seawater or freshwater, changing its state from gas to liquid.

The expansion valve acts as a pressure controller, reducing the pressure from high to low.

The refrigeration system can be subdivided into high-pressure and low-pressure systems.

The compressor increases the pressure of the refrigerant, which is in vapor form, and then it is cooled by the condenser.

The refrigerant, after being cooled and converted to liquid form, still remains under high pressure.

The expansion valve converts the high-pressure liquid refrigerant to a low-pressure liquid form.

The evaporator extracts heat from the environment, causing the refrigerant to boil off and convert from low-pressure liquid to gas.

Safety devices such as the high-pressure cutout prevent system pressurization before the condenser.

The master solenoid valve prevents the flow of refrigerant if a fault occurs in the compressor.

A dryer is used to eliminate any gas, moisture, or oil particles carried over from the compressor.

The thermostatic expansion valve controls the pressure and temperature of the refrigerant entering the evaporator.

A defrost element is provided to periodically defrost the evaporator coil, preventing ice accumulation.

The vapor compression cycle is represented graphically with absolute temperature and entropy, showing the process of compression, condensation, expansion, and evaporation.

The coefficient of performance in a refrigeration system can be understood through the heat energy received, work done, and heat energy rejected.

Pressure and enthalpy graphics illustrate the heat rejected, compression, heat extracted, and expansion processes in the refrigeration system.

Transcripts

friend welcome to marine engineering hub

this is your narrator

ravi gupta today we're gonna talk about

refrigeration system basically

the refrigeration system work on a

principle of

vapor compression cycle what is the

waver compression cycle

i will talk in the later slide

first before starting a refrigeration

system

i will tell you that the refrigeration

system consists of four basic components

first is the compressor

second is the condenser third main

expansion valve

and fourth one is the evaporator so

as you can see this is the compressor

this is the condenser this is the

expansion valve and this is the

evaporator

after that we i will take you to the

other slide

like this before that we need to

understand the

basic concept first is that as you can

see the whole thing

the whole diffusion system is a in

close cycle okay and the refrigeration

vapor coming out from the evaporator is

been

compressed here in compressor okay

and after being compressed the

temperature

of the refrigerant getting raised up

as the temperature of the refrigerant

getting raised up

it has been cooled down by the condenser

either by the mean of sea water or by

fresh water as it getting cooled down

the gas form of refrigerant is changed

into the liquid form

and that liquid form is been converted

into the gas form by

through help of expansion valve the

expansion valve

is a pressure controller which control

which

drop the pressure from high to low

and as it extract the heat from the

evaporator

it convert it form from liquid to

gas okay this is a basic

synopsis of a refrigeration system we

will see

later slide how the whole thing work

first let's see here what i've written

compressor

the main function of a compressor is to

raise the saturation temperature of a

refrigerant

so that it can be cooled by the

condenser

okay so the temperature of the

refrigerant

is been increased so that it can be

cooled by the condensate for that reason

the compression is provided after that

what is happening the

raised saturation temperature of a

represent is cooled by condenser

either by fresh water or sea water to

change its vapor from

one thing i want to tell you that one

thing you need to mine

that the whole system

can also be subdivided into two part

high pressure system

and low pressure system from evaporation

from here to here

this part is a low pressure

thing okay the thing the gas is in low

pressure

zone and from discharge of a compressor

to the inlet of expansion wall this area

is high pressure

basically what is happening as the

represent

is increasing the sorry as a compressor

is increasing the pressure

of the refrigerant it is in vapor form

and

high pressure after it has been cooled

by condenser

it is converted into liquid form but

still it is a high pressure

after that as it passes your expansion

valve

expansion valve is a pressure controller

which converts the high

pressure to low pressure zone but still

it is in liquid form so here this till

the condenser from here

to here this thing is in gas form

here to here it is in liquid form

from expansion valve to the entry of

evaporator

low pressure evaporate

refrigerant is entering the evaporator

and

that is been extracting the heat from

the environment

and converting it into the gas form and

that is going to dug into the compressor

okay now let's see on the bigger system

as you can see the four component here

is one is the compressor condenser

evaporator and that is the expansion bar

along with it it consists of various

component safety device

so first let's see suppose the

represent is coming out from the

evaporator and it is going to

compression

compressor is compressing the

refrigerant gas

as it is compressing the diffusion gap

it is provided with the cutout that if

the valve before the condenser is set

at that time the system this line

may get pressurized to prevent that hp

cutout is provided

okay so the cut out

a safety device provided here as the

refrigerant

is getting compressed now the

high pressure refrigerant gas

form will go and will be cooled in the

condenser

by sea water or it can also be cooled by

a

fresh water and as it is been

cooled the gas form of refrigerant

having high pressure

will be collected in a receiver unit

in liquid form from here the liquid form

the diffusion gas will flow and

as it flow it will go past through a

master solenoid

and then through a dryer so that to

eliminate

any gas or any miss particle or water

particle

or any carryover of the oil particles

of the compressor and through the siphon

class

it will go to solenoid and through a

thermostatic expansion valve

it will convert itself from a high

pressure liquid refrigerant to a low

pressure

liquid refrigerant and as it enter the

evaporator it will extract the heat

from the surrounding from the different

area and

as it extracts the heat it will boil off

and as it boils up it will convert into

a gas form

and it will again go to the compressor

section now i have bypassed

many of the safety device now i will

tell about the

safety device here master

sonol is provided which will prevent

the operation of the

refrigerant which which will prevent the

flow of a refrigerant if any fault occur

in a compressor

as you can see the master solenoid valve

get its signal from a motor controller

or a device which will assess the

condition of the lp and hp

if there is any cut out lp and hp

in that case it will prevent the

starting of the master

solenoid and as the master solar will

close it will prevent the flow of

refrigerant okay now after the condenser

the refrigerant will flow and now will

pass through a dryer this dryer as i

have told is provided so that it can

extract any oil particle or mixed

particle of the

diffusion after that through

here it will pass through a solenoid

this solenoid is a thermostatic control

solenoid

this will come into operation by

monitoring the

condition of the inside the evaporator

if the evaporator temperature inside

is very cool down in that case the

solenoid will be

in closed position but if the

sensing ball says that the temperature

of

inside the refrigerant is high

in that case it will cause the

opening of the solenoid as the solenoid

will open

it will pass through a thermostatic

expansion work

and after the thermostatic expansion

valve it will go to a evaporator

now as the diffusion flow in the

evaporator

it will extract the heat means basically

as it is extracting the heat it is

making the surrounding temperature

of the that area getting cooled

and as it getting cooled it is getting

the refrigerant is getting boiled off

and converting it form from low pressure

liquid refrigerant to a high pressure

liquid refrigerant sorry low pressure

liquid refrigerant to a gas

gas low pressure liquid gas

refrigerant okay now here as you can see

here is a defrost element is provided

that the first element is provided so

that from

time to time the epervator coil

can be defrosted to prevent

the unwanted accumulation of ice over

the surface

so that a good amount of heat transfer

can always take

place okay now i hope you understand

the whole thing

okay now as you can see this is a

vapor compression cycle here this one

represents

the absolute temperature and this one

represent the entropy

this one is the saturated liquid line

and this one

is a saturated vapor line okay this one

is a compression this one is the

condition condensation

and this one is the ipad version and

this one is the

expansion okay so as you can see

from after the evaporation

after the as the gas revenue is coming

out from epa water the pressure is been

increased

and as the pressure is increased this is

the work done by compression

and after that as it has been cooled

down by the condenser

it is getting temperature is getting

down and after that is changing its form

from

gas to liquid form after that

it is again change so as it passes

through a

thermostatic expansion valve it is

getting depressed rise from high

pressure to low pressure and then

as it passes to evaporator extracting

heat

and gaining the heat is changing its

form to liquid again back to the

gas okay now as you know

that this one is the

heat extracted from the environment and

this one is the

here is the heat extracted by the

condenser okay now heat energy received

from the coal chamber

is area under av okay this area

heat rejected in the condenser is equal

to

area under cd okay heat

energy equivalent of work done is area

of the figure abcd a b

c d plus area under d

a okay this one d a

is equal to heat energy rejected

area under c d this one

this one whole area whole area minus

heat energy received is equal to area

under av

that one this one okay so

now if anyone asks you what is the

coefficient of performance then

you can see in simple term is that heat

energy received

that is what are the heat energy we have

received

okay this one is equal to heat energy

equivalent to work done what is the work

done

we are doing the work this one okay

so i hope you understand

now through another thing pressure and

enthalpy graphic you can see

that this one is a heat rejected this

one is a compression

this one is the heat extracted and this

one is the

expansion okay so i hope you understand

the basic concept

of a refrigeration system if you have

the and doubt

please do comment below