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How Does Domestic Refrigerator Work: A Complete Guide - Part 1

Working of Domestic Refrigerators: Chapter 1


Introduction to Domestic Refrigerator


In this module, we will introduce you to domestic refrigerators. We’ll also discuss refrigerator size and capacity. Skip to quiz!!


Domestic Refrigerators

A refrigeration system provides cooling in a closed space by lowering the temperature. The refrigeration systems we use in our homes are domestic refrigerators.


Domestic refrigerators are home appliances that store food and drinks. Unlike a large commercial system, a domestic refrigerator provides cooling to a smaller area.


A refrigerator is a rectangular storage container that can easily fit in a kitchen space. We also use them in ice cream parlors, small stores, and garages to keep food and drinks cold.


A refrigerator transfers heat from the space inside to its external environment. This will cool the space inside to a temperature below that of the room temperature.


If we keep food at room temperature, it can spoil easily. The growth of bacteria present in food slows down when we cool it. The cold temperatures inside a refrigerator help food stay fresh longer.


It’s essential to keep perishable foods like meat and dairy products refrigerated. If we leave milk on the kitchen counter, bacteria will spoil it in two to three hours. However, keeping milk at a lower temperature will allow it to stay fresh for a week or two.


Refrigerator Compartments


Along with the temperature, a refrigerator also controls the air’s humidity. The temperature and the amount of moisture needed to retain the quality of food may vary. The table to the right shows the storage requirements of various food items.


For example, green leafy vegetables keep their crispness and nutrients best in cold, moist air.

They are kept at a temperature in the range of 32-40 °F. On the other hand, blackberries and cherries are kept at 31-32 °F.


A refrigerator has two main sections to satisfy the storage requirements of different food items. These sections include:

  • Refrigerator or fridge, and

  • Freezer.

The optimal temperature range for a refrigerator is 34-42 ℉ to keep food safe, yet unfrozen. The refrigerator section is typically larger than the freezer. We use the refrigerator section for storing ready-to-eat foods, such as dairy products, packaged foods, and beverages.


A refrigerator's freezer section is designed for food that needs to stay frozen, or for long-term storage. That’s why we find the temperature in the range of -6-4 ˚F in a freezer. The freezer is where we keep our frozen vegetables and ice cream.


Refrigerator Size and Capacity


There are a variety of refrigerators available in today’s market to satisfy customer needs. The measurements we need to keep in mind while selecting a refrigerator for any application are:

  • Refrigerator capacity,

  • Refrigerator size, and

  • Family size.

Recall that the capacity of an HVAC system is the ability to heat or cool a given amount of space. If your HVAC system is too small, it won’t be able to efficiently heat or cool your home.

Similarly, if a system has a higher capacity than your home requires, it will heat or cool your home too quickly.


A refrigerator's cooling capacity is the ability of the cooling system to remove heat from stored food items. This differs from an air conditioner that circulates cool air to a room.


Recall that capacity of an air conditioning system is measured in tons. Unlike air conditioners, refrigerator capacity is specified by the storage volume from which heat is removed. It’s the inside volume of a refrigerator, and is expressed in cubic feet or liters.


The volume of the exact space inside a refrigerator is not easy to find. That’s why refrigerator capacity is measured in liters. The capacity of domestic refrigerators varies from about 4 cubic feet (113L) to 29 cubic feet (821L).

As discussed earlier, domestic refrigerators are available in a wide range of sizes and designs. The size of a refrigerator is specified by its overall depth, width, and height.


The capacity and size of refrigerators varies as per our cooling requirements. The image to the right shows the industry recommended capacity of a refrigerator depending upon family size.


A refrigeration system provides cooling in a space by lowering the temperature. A refrigerator has two main sections to satisfy the storage requirements of different food items. Unlike air conditioners, refrigerator capacity is specified by the storage volume from which heat is removed.


 

Domestic Refrigerator Configurations


In this module, we will learn about refrigerator types. We'll also discuss their advantages. Skip to quiz!


Refrigerator Types

Refrigerators we use in our homes are usually one of two types. These include:

  • Freestanding refrigerator, and

  • Built-in and integrated refrigerator.

Freestanding refrigerators are refrigerators that stand on their own. They are unattached, and not built into any furniture or cabinets. They can be easily moved around if a kitchen needs to be rearranged.


Built-in appliances are permanently installed in a kitchen, so they can't be relocated. They are integrated directly into kitchen cabinetry and offer a professional, uniform look.


Freestanding Refrigerators


There are different types of freestanding refrigerators available on the market. These include:

  • Compact and portable,

  • Single door,

  • Two-door,

  • Side by side, and

  • Side by side with a french door configuration.

Compact and portable refrigerators are often used as a supplementary model in family rooms, offices, and other convenient places. Many fit on or under a horizontal work surface in a kitchen.


Compact refrigerators have a smaller capacity—mostly less than six cubic feet. That’s why compact and portable refrigerators have a small freezer compartment for ice trays. They can be installed at any height and relocated easily due to their small size.

Single-door refrigerators provide both fresh and frozen food storage in one compartment. Frozen food storage is located on the top side, whereas fresh food storage, like vegetable storage, is underneath the freezer.


Single-door refrigerators generally have a small capacity—mostly less than 14 cubic feet. Most shelf areas are within reach of someone who’s seated. Freezer compartments have doors that open on the side for easier accessibility.


Unlike a single-door refrigerator, two separate doors are present in a two-door refrigerator. One door is the main door for opening the refrigerator, and another one is for the freezer. This allows us to open the freezer without opening the main door.


Double door refrigerators are larger than those with a single door, and 4-5 member families can fit all of their daily food easily. They are available in capacities of 6.0 cubic feet (170L) to 21.0 cubic feet (595L).


Much like two-door refrigerators, side-by-side refrigerators are divided into two sides. One side is for the fridge compartment, and the other side is for the freezer. Here we find the freezer on the left side and the fridge on the right side.


A side-by-side refrigerator will provide ample vertical space to store taller items. However, horizontal space is slightly lesser than a two-door refrigerator.


Side-by-side refrigerators are split down the middle, and the door hinge swing is shorter. This makes them a better fit in tight spaces. They are available in capacities of 18.0 cubic feet (510L) to 25.0 cubic feet (710L).


Much like the side-by-side, a french door refrigerator is divided in half. Instead of two halves made horizontally, french door models have vertically oriented two sections. The bottom drawer is our freezer section.


Refrigerators with french doors come in different configurations. These types include:

  • Four-, five-, or six-door french door refrigerators, and

  • Quad door refrigerators.

Some of the french door models have two doors at the top and two drawers at the bottom. Quad-door models are divided into quarters. In the quad-door, we can convert one of the bottom doors into a regular refrigerator.



Built-in and Integrated Refrigerators


Unlike freestyle refrigerators, a built-in refrigerator is placed within one’s kitchen cabinets instead of placing it separately. The sides of a built-in refrigerator flush against kitchen cabinetry, and the door comes out a few inches beyond the cabinet doors.


Much like a built-in refrigerator, the sides of an integrated refrigerator are flush against kitchen cabinetry. The difference is that the door of integrated models completely aligns with the cabinetry. When the fridge door is closed, an integrated refrigerator looks identical to any other cabinet in a kitchen.


Both integrated and built-in refrigerators are available in different designs. The compressor of a built-in refrigerator is mounted on the top side. In contrast, the compressor is on the bottom side of an integrated refrigerator.

Built-in and integrated refrigerators deliver a sleek and luxurious style we can’t achieve with freestanding models. They are expensive and designed for luxury or high-end kitchens.


We cannot move integrated and built-in refrigerators if our kitchen needs to be rearranged. However, we can customize them to fit correctly inside our kitchen.


The types of refrigerators available on the market today are freestanding, built-in, and integrated. Freestanding refrigerators, as the name suggests, stand freely. Built-in and integrated refrigerators are placed within kitchen cabinetry instead of placing separately.


 

Freezers


In this module, we will learn freezer configurations and types. We’ll also discuss their applications. Skip to quiz!


Freezer Configuration


Recall that refrigerators are classified based on their arrangement as freestanding, built-in, or integrated. Refrigerators are also classified according to the placement of the freezers inside them. This includes:

  • Top mount freezers, and

  • Bottom mount freezers.

As the name implies, a top-mount freezer has its freezer placed above the fridge. A bottom-mount freezer will have its freezer positioned below the fridge.


As discussed earlier, single-door and two-door refrigerators have a freezer compartment at the top. Two-door refrigerator variants are also available with a freezer at the bottom. Recall that all types of french door refrigerators have a freezer at the bottom.


Most of these top and bottom freezer units have refrigerator cabinets with single swing doors. The compartment of a bottom freezer can have a drawer or a swing door. Meanwhile, the freezer compartment of a top-mount is always a swing door.


Bottom-mount freezers with a swing-door or a pull-drawer have organizing baskets. This will help you organize and access your frozen goods more easily than top-mount refrigerators.


A freezer’s configuration will affect its daily use. Since we tend to open the fridge compartment more often than the freezer, having the fridge at eye level will make it easier to use. We don't have to bend down each time to reach something inside the fridge.



Freezer Types


With a modern fridge, we require a lot of room to accommodate the refrigerator system. But without the freezer, a refrigerator system can be small and will fit into the tiniest of spaces.


Recall that the temperature in a freezer is below 0℉, so we can store food items for a longer time. In a freezerless refrigerator, there will be no freezer compartment. This is why they’re used in small shops to keep drinks or snacks for a limited time.


Apart from a freezerless refrigerator, we might also need a machine that its sole purpose is to store frozen food. For extra or long-term frozen food storage, there are dedicated freezers. These include:

  • Chest freezers, and

  • Upright freezers.

Chest freezers are laid out horizontally with their doors opening at the top. They either come with a solid hinged-top door or a sliding glass door. Chest freezers are commonly used in ice cream parlors, utility rooms, and house basements.


Upright freezers stand vertically – they look a lot like regular refrigerators except that they don’t have a fresh-food compartment. It’s just a slim and tall freezer compartment, compared to wide and bulky chest freezers. Upright freezers are used in smaller garages or basements to save space.


Because of the built-in shelves, upright freezers are easier to organize compared to chest freezers. Upright freezers are also easier to reach into, as the compartments are shallow. Meanwhile, a chest freezer only has one deep compartment for everything.


A top-mount freezer has its freezer placed above the fridge. A bottom-mount will have its freezer positioned below the fridge.


In a freezerless refrigerator, as the name implies, there will be no freezer compartment. Chest freezers and upright freezers are dedicated freezers to store frozen food.



 

Refrigeration Cycle


In this module, we will recall the refrigeration cycle used in refrigeration systems. We’ll also discuss the components of refrigerators. Skip to quiz!


Refrigeration Cycle


A refrigerator removes heat from a closed space by using the basic refrigeration cycle.

Recall that the four main components of the basic refrigeration cycle are:

  • Compressor,

  • Condenser,

  • A metering device, and

  • Evaporator.


Recall that a refrigerator works by transferring heat from the space inside to the outside. It uses refrigerant to do this. Refrigerant is fluid used in refrigeration systems to transfer heat.


Recall that ODP is the capacity of refrigerant to damage the ozone layer. Recall that GWP is the capacity of refrigerant to cause global warming. These factors measure the environmental impact of refrigerant.


Earlier generations of refrigerators used R-134a refrigerant. A majority of modern domestic refrigerators use R-600a refrigerant. This is because R-600a has a lower ODP and GWP than R-314a.


The molecules of vapor refrigerant are pressed closer together to increase the pressure. As pressure increases, temperature also increases. Then high-pressure, high-temperature vapor refrigerant enters the condenser.


Heat is removed from the vapor refrigerant by the flow of relatively cool air over the condenser. As high-temperature vapor refrigerant transfers its heat to the cool air, it changes from vapor to liquid. Liquid refrigerant is then sent to an expansion device.

When refrigerant enters the throttling valve, it expands and releases pressure. Consequently, the temperature drops at this stage, as pressure and temperature are related. Liquid refrigerant is then circulated through an evaporator.


In the evaporator, the refrigerant absorbs heat from the closed inside space of the refrigerator. Let’s discuss each of these components in detail.



Compressors


Recall that a compressor’s main job is to increase the pressure of refrigerant. We see the following types of compressors in a refrigerator:

  • Reciprocating compressors,

  • Scroll compressors, and

  • Screw compressors.

These are categorized based on how they work.

Recall that a motor drives reciprocating compressors.They have a piston and cylinder, just like a car engine.


Domestic refrigerators usually have air-tight, hermetically sealed reciprocating compressors. Recall that the motor and the compressor are contained and sealed inside a single shell in hermetic compressors. They are also relatively quiet, which makes them ideal for household use.


Recall that scroll compressors consist of two matching scrolls, one stationary and the other rotating around the first. One scroll rotates around the other in a circular motion to compress refrigerant.


Screw compressors also use a circular motion to compress refrigerant. That’s why they’re sometimes called rotary screw compressors.


Condensers


Recall that a condenser’s main job is to cool down refrigerant. The main types of condensers in refrigerators are:

These condensers are classified based on their structure.


A wire and tube condenser is similar to a fin and tube condenser. The difference is, there are no plate-like fins in wire and tube condensers. In their place, thin wires are used. The wires act as fins to increase the heat transfer area.


The reason they use wires in place of plate fins is that the condenser can be seen outside the refrigerator. If we use plate fins, it may cut someone's hand. So we use wires that can be made relatively more safe.


Plate surface condensers are flat, as shown in this image. The refrigerant carrying tubes are attached to the outer walls of a refrigerator. Unlike fin tube condensers, the whole body of the refrigerator acts like a fin and no separate fins are provided.


Metering Devices

Recall that a metering device’s job is to decrease the pressure of refrigerant. Refrigerators mainly use two main types of metering devices:

  • Capillary tube, and

  • Thermal expansion valve (TXV).

We’ll discuss how these metering devices work in refrigerators in detail.


Capillary tubes have a small diameter, which reduces the amount of refrigerant that can flow through at any given time. This decreases the pressure of refrigerant.


The refrigerant in a tube starts off with very high pressure. As it flows through this long thin capillary tube, refrigerant loses its pressure, and we only get a slow stream of water at the end.


Capillary tubes are more susceptible to clogging and damage. That’s why modern refrigerators use thermostatic expansion valves. TXVs control the amount of refrigerant that flows into an evaporator based on the evaporator outlet temperature.


Evaporators


Recall that an evaporator’s job is to absorb heat from the space inside a refrigerator.

Refrigerators mainly use two main types of evaporators:

  • Bare tube, and

  • Plate surface evaporators.

Bare tube evaporators are the most simple type of evaporator. These evaporators are generally just refrigerant tubes that are made of either copper or aluminum. There is refrigerant inside the refrigerant tube, which changes from liquid to vapor by absorbing heat from the air.


Plate surface evaporators are flat, as shown in this image. These evaporators are made up of two plates that are joined together. Usually the two plates are made of aluminum because it conducts heat well.

Liquid refrigerant flows through a tube made between the two plates. This tube carrying refrigerant is the raised part of the plate that we can see in this image.


Plate surface evaporators are an improvement over bare tube evaporators. This is because they have a higher surface area for air to flow over them. The higher the surface area, the more heat can be transferred into refrigerant.


In plate surface evaporators, food can be placed directly on the plate for more effective cooling. This improves heat transfer even more.


Unlike bare tube evaporators, there are no tubes in plate surface evaporators. This makes them easy to clean and defrost.


Plate surface evaporators are less likely to leak refrigerant and safer to handle. This is because plates are stronger than tubes. As there are no fins, there is no danger of cutting our hands. This makes them suitable for refrigerators.


We see the following types of compressors in refrigerators:

  • Reciprocating compressors,

  • Scroll compressors, and

  • Screw compressors.

We mainly use two types of condensers in refrigerators:

  • Wire and tube condenser, and

  • Plate type condenser.

The two main types of metering devices used in refrigerators are:

  • Capillary tube, and

  • Thermal expansion valve.

Refrigerators mainly use the two main types of evaporators:

  • Bare tube, and

  • Plate surface evaporators.


 

Secondary Components


In this module, we will learn the secondary components used in a refrigerator. We’ll also discuss their function. Skip to quiz!


Airflow Systems


Recall that condensers cool down refrigerant by exchanging heat with the air around it. The air can be circulated around the condenser coils by using either of the following systems:

  • Natural draft, and

  • Forced draft airflow system.

Recall that natural draft airflow is airflow without the use of fans. Natural airflow depends on the principle that hot air naturally rises and cool air sinks.


If a bottle surface is heated, the air inside the bottle rises. Similarly, hot refrigerant in condenser coils transfers heat to the air around it. This air becomes warm and starts to rise above the condensing unit.


Cold air from the surroundings moves into the place of the warmer air, because cold air sinks.

As a condenser runs, this process repeats and can be summarized as:

  • Hot air keeps rising, and

  • Cool air sinks to take hot air’s place.

This cycle repeats to create a natural flow of air.


Because the natural airflow system depends on air to move naturally, we can't control how fast it cools. It's like waiting for a cool breeze on a hot summer day. That’s why we find this type of system in older refrigerators.


To overcome the flaws in natural draft airflow, forced draft airflow was invented. Both induced and forced draft airflow use fans to direct the flow of air. As fans turn on and go faster or slower, we can better control the amount of air flowing over a condenser.



Blower Fans

Most modern refrigerators use a fan to blow air over the coils. There are two blower fans used in refrigerators. These include:

  • Condenser fan, and

  • Evaporator fan.

Condenser fans are located under refrigerators. They’re used to force air over compressors and condenser coils to cool them.


Evaporator fans are located inside refrigerators. Unlike natural air circulation, the fan moves air around the cool evaporator coils inside a refrigerator. This cooled air is then distributed inside the refrigerator to cool the food stored inside.


Filter Driers


The presence of moisture inside a system can damage it. We use a filter drier to remove moisture from and filter refrigerant. It removes small particles of dirt, water, and debris from refrigerant.


Filter driers are placed after a condenser and before an expansion device.


Filter driers consist of two parts; the shell and the core. The core is in the inner part, which absorbs moisture. Whereas, the shell is the outer metal covering.


When liquid refrigerant moves inside a drier, it will pass through the core. The core of a drier absorbs moisture and dirt particles. This cleans refrigerant coming out of a drier.



Liquid Line Receiver Tanks

A liquid line receiver tank is a storage tank that stores excess liquid refrigerant. There is a large amount of liquid refrigerant flowing in the refrigerant circuit of a refrigerator. We need a container to store this.


A receiver tank is installed in the refrigerant line, as close as possible to the outlet of the condenser. With a receiver, a system can have liquid refrigerant back up if the refrigerant level in the condenser drops due to leaks.


Accumulator Tanks


Recall that liquid refrigerant can cause the failure of a compressor. We use accumulator tanks to prevent liquid refrigerant from entering compressors.

They’re placed between the evaporator outlet and the compressor suction line.


If liquid refrigerant does not boil off completely in an evaporator, it can enter the compressor. An accumulator placed at the compressor suction line ensures that only vapor refrigerant enters the compressor.


Most modern refrigerators use fans to blow air over condensers and evaporator coils. We use filter driers to remove moisture from and filter refrigerant. A liquid line receiver tank is a storage tank that stores excess liquid refrigerant.


 

Question #1: Why do people need domestic refrigerators?

  1. To cool a room

  2. To store food for a longer duration

  3. To heat food

  4. To produce cool air

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Answer: To store food for a longer duration

A domestic refrigerator is a home appliance to store food and drinks.

The cold temperatures inside the refrigerator help food stay fresh longer.


Question #2: What are the two compartments inside the refrigerator?

  1. Ice maker and water maker

  2. Ice maker and veg food

  3. Fridge and freezer

  4. Veg and non-veg food

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Answer: Fridge and freezer

A refrigerator has two main sections to satisfy the storage requirements of different food items.

These sections include:

  • Refrigerator or fridge, and

  • Freezer

Question #3: A freezer’s temperature is usually greater than the temperature of the fridge or refrigerator.

  1. True

  2. False

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Answer: False

The temperature in the freezer is less than the temperature of the fridge or refrigerator.

The temperature range for the refrigerator is 34 ℉ to 42 ℉ and -6 ˚F to 4 ˚F in a freezer.


Question #4: How do we measure the capacity of a refrigerator?

  1. Ohms

  2. Tons

  3. Cubic feet

  4. Kg or newton

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Answer: Cubic feet

Refrigerator capacity is specified by the storage volume from which heat is removed.

It is the inside volume of the refrigerator and is expressed in cubic feet or liters.


Question #5: What is the capacity of compact refrigerators?

  1. More than 8 cubic feet

  2. Mostly less than 6 cubic feet

  3. 10 cubic feet

  4. 20 cubic feet

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Answer: Mostly less than 6 cubic feet

Compact refrigerators have a smaller capacity—mostly less than six cubic feet.


Question #6: One door is for the refrigerator, and another one is for the freezer in a single-door refrigerator.

  1. True

  2. False

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Answer: False

False! Single-door refrigerators provide both fresh and frozen food storage in one compartment.


Question #7: A double-door refrigerator has a smaller capacity than a single-door refrigerator.

  1. True

  2. False

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Answer: False.

Double door refrigerators are larger than a single door.

They are available in 6.0 cu.ft. (170L) to 21.0 cu.ft. (595L) capacity.


Question #8: Which type of refrigerator gives more vertical space to store taller food items?

  1. Single door refrigerator

  2. Double door refrigerator

  3. Side by side refrigerator

  4. Compact refrigerator

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Answer: Side by side refrigerator

A side-by-side refrigerator will provide ample vertical space to store taller items.

However, horizontal space is slightly lesser than a two-door refrigerator.


Question #9: French door refrigerator configuration is the same as that of a side-by-side fridge.

  1. True

  2. False

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Answer: False.

The freezer compartment is on the left side of the fridge in side by side refrigerator.

Although, the freezer compartment is on the bottom side of the fridge in the french door refrigerator.


Question #10: Built-in refrigerators are unattached and not built into any furniture or cabinets.

  1. True

  2. False

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Answer: False.

Unlike freestyle refrigerators, the built-in refrigerator is placed on our kitchen cabinet instead of placing separately.


Question #11: In which type of refrigerator does the door of the fridge completely align with the cabinetry?

  1. Single door refrigerator

  2. Double door refrigerator

  3. Integrated refrigerator

  4. Built-in refrigerator

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Answer: Integrated refrigerator

The door of an integrated refrigerator completely aligns with the cabinetry.


Question #12: A top-mount freezer has its freezer positioned below the fridge.

  1. True

  2. False

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Answer: False.

A top-mount freezer has its freezer placed above the fridge. A bottom mount freezer will have its freezer positioned below the fridge.


Question #13: What is the door type of a bottom freezer compartment? (Select all that apply)

  1. Slide down type

  2. Pull-drawer style

  3. Slide up type

  4. Swing-door style

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Answer: Pull-drawer style and Swing-door style

The compartment of a bottom freezer type can be either a pull-drawer or swing-door.


Question #14: How many freezers are present in a freezerless refrigerator?

  1. Two

  2. One

  3. Zero

  4. More than two

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Answer: Zero

In a freezerless refrigerator, as the name implies, there will be no freezer compartment.


Question #15: Which type of freezer consumer more horizontal space?

  1. Chest freezer

  2. Bottom mount freezer

  3. Top mount freezer

  4. Upright freezer

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Answer: Chest freezer

Chest freezers are wide and bulky, thus require more horizontal space compared to other freezers.


Question #16:Upright freezers are easier to organize compared to chest freezers.

  1. True

  2. False

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Answer: True.

Upright freezers are easier to organize compared to chest freezers. They are also easier to reach into as the compartments are shallow.


Question #17: After the metering device, which component does the refrigerant travel to next in the refrigeration cycle?

  1. Condenser

  2. Compressor

  3. Metering Device

  4. Evaporator

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Answer: Evaporator

After the metering device, refrigerant goes to the evaporator.


Question #18: Which refrigerant is used in most modern domestic refrigerators?

  1. R-717

  2. R-20

  3. R-600a

  4. R-134a











Answer: R-600a

Earlier generations of refrigerators ran on R134A, tetrafluoromethane. The majority of modern domestic refrigerators run on R600A, isobutane.


Question #19: Which types of compressors are used in domestic refrigerators? (Select all that apply)

  1. Reciprocating Compressor

  2. Scroll Compressor

  3. Screw Compressor

  4. Centrifugal Compressor

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Answer: Reciprocating Compressor , Scroll Compressor and Screw Compressor


We see the following types of compressors in trefrigerators.

  • Reciprocating compressors,

  • Scroll compressors, and

  • Screw compressors


Question #20: How do wire and tube type condensers used in refrigerators differ from finned tube condensers found in air conditioners?

  1. They have fins in place of wires

  2. They have wires in place of fins

  3. They are same

  4. They have both fins and wires

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Answer: They have wires in place of fins

Unlike finned tube condensers, wire and tube condensers have thin wires in place of fins.


Question #21: Which type of metering device do we prefer in modern refrigerators?

  1. Electronic expansion valve

  2. Capillary tube

  3. Thermostatic expansion valve

  4. Nozzle

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Answer: Thermostatic expansion valve

Modern refrigerators use thermostatic expansion valves to control the amount of refrigerant.


Question #22:In which type of evaporator food can be placed directly on the evaporator plate for more effective cooling?

  1. Finned Tube Evaporators

  2. Plate surface evaporator

  3. Bare tube evaporator

  4. Shell and Tube Evaporators

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Answer: Plate surface evaporator

In plate surface evaporators, food can be placed directly on the plate for more effective cooling.


Question #23: Why do we prefer plate-type evaporators in domestic refrigerators? (Select all that apply)

  1. They are safe to handle

  2. They are easy to clean

  3. They have single plate

  4. They are less likely to leak

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Answer: They are safe to handle, They are easy to clean and They are less likely to leak

Plate surface evaporators are easy to clean and defrost. They are less likely to leak refrigerant and safe to handle.


Question #24: What is the principle that natural airflow depends on?

  1. Conservation of airflow

  2. Hot air sinks, cold air rises

  3. Hot air rises, cold air sinks

  4. All of these

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Answer: 3. Hot air rises, cold air sinks

Hot air rises, and cold air sinks. Since natural airflow does not use fans, this is a natural principle that moves air.


Question #25: Which of the following airflow systems uses fans to direct flow of air? (Select all that apply)

  1. Natural airflow system

  2. Induced draft airflow system

  3. Forced draft airflow system

  4. Cold air rise airflow system


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Answer: Induced draft airflow system and Forced draft airflow system

Both induced and forced draft airflow use fans to direct the flow of air.


Question #26: Condenser fans and evaporator fans work on the principle of the natural airflow system.

  1. True

  2. False

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Answer: False.

Unlike natural air circulation, condenser and evaporator fans move air around the coils of a refrigerator.


Question #27: Filter driers add moisture to refrigerant.

  1. True

  2. False

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Answer: False.

Filter driers are used to remove moisture from and filter refrigerant.


Question #28: Where are liquid line receiver tanks located?

  1. Inlet of the condenser.

  2. Outlet of condenser

  3. Inlet of evaporator

  4. Inlet of compressor

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Answer: Outlet of condenser

A receiver tank is installed in the refrigerant line, as close as possible to the outlet of the condenser.


Question #29:Which of the following component is used to prevent liquid refrigerant from entering the compressor?

  1. Filter drier

  2. Accumulator tank

  3. Liquid line receiver tank

  4. Dehumidifier

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Answer: Accumulator tank

An accumulator tank is used to prevent liquid refrigerant from entering the compressor.

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