How does a Refrigerator work?

Summary

This video explains the working principles of modern refrigerators, starting with the basic vapor compression cycle. It highlights key components like the throttling device, evaporator, compressor, and condenser, and describes how cold liquid is circulated to achieve cooling. The video also addresses common issues such as frost buildup and shows how modern solutions like digital inverter compressors improve energy efficiency and temperature control. The digital inverter technology, which allows variable compressor speeds, significantly enhances performance and reduces energy consumption by at least 40%, compared to traditional single-speed compressors.

Takeaways

• 🧊 The basic principle of refrigerators is to pass a colder liquid continuously around the object to be cooled.
• 🌡️ A throttling device, often a capillary tube, is crucial for creating a cold liquid by reducing pressure and causing the refrigerant to evaporate.
• 💧 The refrigerant should be able to change phase with pressure variation at normal temperatures, which is essential for the refrigeration cycle.
• 🔄 The refrigeration cycle involves the refrigerant going through a series of transformations: from liquid to vapor and back to liquid.
• 🌀 An evaporator fan helps maintain different temperature levels inside the refrigerator by circulating the cold refrigerant.
• 🔧 The compressor raises the pressure of the refrigerant back to its initial value after it has been throttled and evaporated.
• 🌡️ The condenser, located outside the refrigerator, converts the high-pressure vapor back into a liquid by releasing heat to the surroundings.
• ❄️ Frost formation in the freezer compartment is a common issue, which can be mitigated by occasional defrosting or using a heating rod.
• 🔧 Modern refrigerators use a compact condenser arrangement and a cooling fan to improve heat rejection and efficiency.
• 🏡 The capillary tube in home refrigerators is often hidden inside the evaporator exit coil, which optimizes the refrigeration effect.
• 🔋 Digital inverter compressors offer variable speed control, leading to smoother temperature management and at least 40% less energy consumption compared to single-speed compressors.

Q & A

What is the basic principle behind the operation of a refrigerator?

The basic principle of a refrigerator is to pass a colder liquid continuously around the object to be cooled. This creates a cooling effect by absorbing heat from the object.

How is the cold liquid flow achieved inside a refrigerator?

A cold liquid flow is achieved using a throttling device, like a capillary tube. The refrigerant is in a high-pressure liquid state at the inlet, and as it flows through the tube, the pressure drops, lowering the boiling point and causing part of the refrigerant to evaporate, which cools the remaining liquid.

What role does the compressor play in a refrigerator?

The compressor raises the pressure of the refrigerant vapor back to its initial high-pressure state after the cooling process. This allows the refrigeration cycle to repeat continuously.

What is the purpose of the condenser in a refrigerator?

The condenser converts the high-pressure vapor refrigerant into a liquid by releasing heat to the surroundings. This occurs after the refrigerant is compressed and before it returns to the throttling device.

What is the role of the evaporator in the refrigeration cycle?

The evaporator absorbs heat from the refrigerated space. As the refrigerant passes through the evaporator, it absorbs heat and evaporates, causing the temperature in the space to decrease.

Why does frost form in the freezer compartment, and how is it removed?

Frost forms when the moisture in the circulating air condenses on the cold evaporator coil. This frost can impede heat transfer, making the refrigerator inefficient. To remove it, modern refrigerators use a heating rod to melt the frost, and the water is collected in a pan at the bottom of the refrigerator.

Why do modern refrigerators have a compact condenser instead of visible condenser fins at the back?

Modern refrigerators use a compact condenser arrangement with a cooling fan, which achieves the same heat rejection purpose as the older, larger condenser fins. The fan also helps evaporate water from the defrosting process.

Why do some refrigerators only have one visible refrigerant line instead of two?

Modern refrigerators often have only one visible line because the capillary tube, which carries the cold refrigerant liquid, is routed inside the evaporator exit coil. This design improves the cooling efficiency by bringing the refrigerant temperature down further.

What is the benefit of using a digital inverter compressor in modern refrigerators?

Digital inverter compressors allow variable speed operation, which leads to smoother temperature control, greater energy efficiency (up to 40% less energy consumption), and increased durability compared to traditional single-speed compressors that switch abruptly between on and off states.

How does the digital inverter compressor control motor speed?

In a digital inverter compressor, AC power is converted to DC using a controller, which supplies electric power at variable frequencies to control the motor speed accurately. This allows for more precise temperature regulation inside the refrigerator.

Outlines

00:00

🧊 How Refrigerators Work: Basic Principles and Components

This paragraph introduces the basic principles behind the operation of refrigerators, which are essential appliances in modern households. It explains that refrigerators work by circulating a colder liquid around the object to be cooled. The liquid's cooling effect is achieved through a device called a throttling device, such as a capillary tube, which causes a significant pressure drop and a subsequent drop in temperature. The process involves converting the refrigerant from a high-pressure liquid to a low-pressure vapor, absorbing heat from the surroundings in the evaporator, and using a compressor to return the refrigerant to its initial state for continuous cooling. The paragraph also mentions issues like frost buildup and the use of a heating rod to remove frost, along with the compact condenser arrangements found in modern refrigerators.

05:00

🌡️ Temperature Distribution and Capillary Tube Innovations

This paragraph delves into the temperature distribution within different parts of a refrigerator, highlighting the significance of the capillary tube design in enhancing refrigeration efficiency. It explains that, unlike older designs with visible external lines, modern refrigerators often use a straight capillary tube that runs inside the evaporator exit coil. This setup helps improve the refrigeration effect by reducing the temperature of the refrigerant in the capillary tube, leading to a greater temperature drop and enhanced cooling. The design also ensures that the refrigerant in the evaporator exit line remains in pure vapor form, which is ideal for compressors. Additionally, the paragraph introduces the concept of digital inverter compressors, which adjust compressor speed to maintain a smooth and efficient temperature control inside the refrigerator, reducing energy consumption by at least 40% compared to traditional single-speed compressors.

Keywords

💡Refrigeration

Refrigeration is the process of cooling a space or substance below environmental temperature. In the video, refrigeration is explained as the primary function of a refrigerator, achieved by circulating a cold liquid over the object to be cooled. This is the central concept that the entire refrigerator system is built around.

💡Throttling Device

A throttling device is used to reduce the pressure of the refrigerant as it flows through it. In this case, a capillary tube is used to lower the pressure, causing the refrigerant to evaporate and cool. This device is crucial for the refrigeration cycle, as it helps generate the cold liquid that cools the interior of the refrigerator.

💡Evaporator

The evaporator is a heat exchanger inside the refrigerator where the refrigerant absorbs heat and evaporates. As it evaporates, it cools the space around it. The video mentions the evaporator's role in maintaining different temperature levels inside the refrigerator with the help of airflow circulation.

💡Compressor

The compressor is the component that raises the pressure of the refrigerant back to its initial value after it has absorbed heat and evaporated. This high-pressure refrigerant is then sent to the condenser. The compressor is essential to keeping the refrigeration cycle in motion, making it a vital part of the system.

💡Condenser

The condenser is a heat exchanger that cools down the high-pressure vapor from the compressor, converting it back into liquid. Located outside the refrigerator, it releases heat into the surrounding environment. The condenser is key to resetting the refrigerant to its liquid state so it can pass through the throttling device again.

💡Vapor Compression Cycle

The vapor compression cycle is the process that allows refrigerators to provide continuous cooling. It involves refrigerant being cycled through a series of stages: compression, condensation, throttling, and evaporation. This cycle is repeated to maintain a consistent cooling effect inside the refrigerator.

💡Digital Inverter Compressor

A digital inverter compressor controls the speed of the compressor more efficiently than traditional single-speed compressors. It adjusts the compressor's speed based on cooling needs, which leads to energy savings and smoother temperature control. The video highlights this as a modern innovation that increases refrigerator efficiency by at least 40%.

💡Heat Transfer

Heat transfer refers to the movement of heat from one area to another. In the context of a refrigerator, it happens when the refrigerant absorbs heat in the evaporator and releases it in the condenser. Effective heat transfer is crucial for the refrigeration process to work efficiently.

💡Frost Formation

Frost formation occurs when moisture in the air inside the refrigerator condenses and freezes on the cold evaporator coils. This can reduce the refrigerator's efficiency over time. The video discusses how modern refrigerators handle this issue by using a heating rod to defrost the coils, preventing ice buildup.

💡Coefficient of Performance (COP)

The coefficient of performance (COP) measures a refrigerator's efficiency, defined as the ratio of cooling output to energy input. A higher COP means the refrigerator is more efficient. The video uses this term to explain how the performance of refrigerators can be evaluated and improved over time.

Highlights

Refrigerators work on the principle of circulating a colder liquid around the object to be cooled.

The throttling device is a crucial component that reduces the pressure of the refrigerant, causing it to evaporate and cool.

As the refrigerant evaporates, it absorbs heat from the surrounding area, which is the basic cooling effect in a refrigerator.

The evaporator is the heat exchanger responsible for maintaining different temperature levels inside the refrigerator.

A compressor raises the pressure of the refrigerant, allowing it to repeat the cooling cycle.

The condenser, located outside the refrigerator, helps convert the high-pressure vapor back into a liquid by releasing heat.

Frost buildup on the evaporator coils reduces refrigerator efficiency, which is countered by occasional defrosting using a heating rod.

Modern refrigerators often use compact condensers with fans to efficiently reject heat and evaporate water from defrosting.

Refrigerators utilize two refrigerant lines: one for cold liquid to the evaporator and another for vapor exit, but only one is visible externally.

In some designs, the capillary tube is positioned inside the evaporator exit line, improving cooling efficiency by exchanging heat.

The capillary tube's contact with the evaporator exit line enhances the refrigeration effect and protects the compressor by ensuring the refrigerant is pure vapor.

A filter dryer is used to remove moisture from the refrigerant to ensure smooth compressor operation.

Digital inverter compressors, unlike older on-off compressors, allow variable speeds, ensuring smoother and more efficient temperature control.

Digital inverter technology converts AC power to DC, allowing variable motor speeds for better energy efficiency.

Refrigerators with digital inverter compressors consume at least 40% less energy than those with single-speed compressors.

Transcripts

have you ever wondered how the

refrigerators in your home work

refrigerators which have become an

integral part of every household work

based on some simple and interesting

scientific principles

[Music]

beginning with the basic refrigerator

model this video will elaborate on the

operation of modern refrigerators along

with the secrets behind their high

energy efficiency

the basic principle of refrigerators is

simple simply pass a colder liquid

continuously around the object to be

cooled

let's see how this continuous cold

liquid flow is achieved inside a

refrigerator

a simple device called a throttling

device is the most crucial component of

refrigerators here a capillary tube is

used as throttling device a cold liquid

is produced using the throttling

phenomenon for effective throttling at

the inlet the refrigerant should be at a

liquid state under high pressure

the throttling device is an obstruction

to the flow so a huge pressure drop

occurs when the liquid flows through it

as the pressure drops the boiling point

of the liquid comes down thus the

refrigerant liquid evaporates the energy

required for such evaporation comes from

the refrigerant so its temperature drops

if you check the temperature across the

throttling device you will notice this

drop

please note that only a portion of the

refrigerant is evaporated here this is

one important property of the

refrigeration fluid it should be able to

change the phase while varying the

pressure under normal temperatures

the next phase is simple just pass this

cold liquid over the body which is to be

cooled

during the heat absorption process the

refrigerant further evaporates and

transforms into pure vapor

since there is phase change during this

process the refrigerant temperature does

not increase this heat exchanger is

called the evaporator

with the help of clever airflow

circulation inside the refrigerator

using an evaporator fan one can maintain

different temperature levels

so we have produced the required

refrigeration effect if we can take this

low pressure refrigerant to the state

before throttling that is high pressure

liquid we will be able to repeat this

process

so the first step is to raise the

pressure

a compressor is used for this purpose

the compressor will raise the pressure

back to its initial value

you can see that a reciprocating type

compressor is used here

however since it is compressing gas

along with pressure the temperature will

also increase this is unavoidable

now the refrigerant is high pressure

vapor to convert it to a liquid stage we

introduce another heat exchanger this

heat exchanger is fitted outside of the

refrigerator thus it will liberate heat

to its surroundings vapor will be

converted to liquid and temperature will

reach a normal level this heat exchanger

is known as a condenser

now the refrigerant is back to its

initial state so it can be fed to the

throttling device again

just by repeating this cycle over and

over we will be able to achieve a

continuous cooling effect this cycle is

more specifically called the vapor

compression cycle

refrigerator performance can be

evaluated using a term called

coefficient of performance

performance is output divided by input

so the coefficient of performance can be

easily defined as follows

this is the most basic refrigerator

possible ever this refrigerator will

work well in theory however

in practice it will face many issues

let's see what these issues are and how

to overcome them

one major issue is the frost developed

in the freezer compartment

the circulated air has moisture content

inside it so when the air comes in

contact with the cold evaporator coil

they will condense and form a frost

around the coil

such ice coating prevents further heat

transfer and the refrigerator becomes

inefficient over time

one great way to solve this issue is to

remove frost occasionally with the help

of a heating rod

this is why you can see a pan and water

condensate at the bottom of your

refrigerator

moreover in modern refrigerators you

won't be able to see the condenser fins

at the back of the refrigerator instead

they use a compact condenser arrangement

this compact arrangement is assisted by

a cooling fan and the same heat

rejection purpose is achieved here the

hot air expelled by the fan can be used

to effectively evaporate the water

condensate formed during the frosting

the improved refrigerator looks like

this

an interesting temperature distribution

in different parts of the refrigerator

is illustrated here

the temperature drop across the

capillary tube is also clearly depicted

here

you can see two refrigerant lines

outside the refrigerators one takes the

cold liquid from the capillary tube to

the evaporator coil and the other the

exit vapor line from the evaporator

however if you check your home

refrigerator you can see only one line

on the outside

why is this the case

the most crucial part of the

refrigerator is the capillary tube which

need not be a spring-like device it can

be a long straight tube as shown

temperature variation in the new

straight capillary tube is depicted here

you see only one line on your home

refrigerator because this straight

capillary tube runs inside the

evaporator exit coil

this simple technique has major

advantages

we know that during the heat absorption

process at evaporator the refrigerant

temperature does not rise only its phase

changes

this means that if we allow the

capillary tube to come into contact with

the evaporator exit line this will bring

down the capillary tube refrigerant

temperature by a great degree

this in effect will lead to greater

temperature drops in the capillary tube

thus creating a better refrigeration

effect

on the other hand the evaporator exit

coil absorbs heat this will ensure that

the refrigerant in the evaporator exit

line has transformed into pure vapor

this is good for compressors which are

designed to handle only pure vapor

a filter dryer is used to remove any

moisture contents in the refrigerant

which might become trapped in the

compressor operation

let us now explore the most recent

innovation in refrigerators which has

transformed modern refrigerators

digital inverter compressors

a compressor is the heart of any

refrigerator and is the device that

gives life to the whole system

you might have noticed that the

compressors in old refrigerators will

either be on or off this is a single

speed technology when the inside

temperature of the refrigerator reaches

an optimum level the compressor will be

turned off when the temperature goes

above a certain limit the compressors

will be turned on

so you can see that the temperature

control inside the refrigerator is not

smooth moreover such abrupt speed

variation of the compressors will lead

to durability issue to the compressor

components

with the help of digital inverter

compressor a variable compressor speed

is possible

thus a smooth and efficient evaporator

temperature control can be achieved here

here the ac power is converted to dc

using a controller the controller then

supplies electric power in variable

frequency to accurately control the

motor speed

the most common motor used in this

technology is a bldc digital inverter

compressor consumes at least 40 percent

less energy compared to the single speed

compressors

we hope this video gives you a clear

insight of the working of a modern

refrigerator we request your support at

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