Commercial Refrigeration Systems
In this module, we will learn about commercial refrigeration. We’ll also learn about the parameters considered while choosing a commercial refrigeration system. Skip to quiz!
Introduction to Commercial Refrigeration Systems
Commercial refrigeration systems are found in places like supermarkets, hotels, malls, and pharmaceutical facilities. These work with larger loads and for longer periods of time. If a commercial refrigeration system does not work properly, the entire business is at risk.
Some businesses that require commercial refrigeration are:
Food and beverage companies,
Supermarkets,
Convenience stores, and
Restaurants.
Commercial refrigeration systems come in different shapes and sizes.
Some of the commercial refrigeration systems are:
Rack refrigerators,
Walk-in coolers, and
Ice plants.
We’ll learn about these refrigeration systems in upcoming modules.
Commercial refrigeration systems work on the basic refrigeration cycle. The four components of the basic refrigeration cycle are:
Compressor,
Condenser,
Metering device, and
Evaporator.
Let’s watch a video to recall the basic refrigeration cycle.
A refrigeration system generally consists of basic refrigeration cycle components. We connect all these components in a series to get a cooling effect.
How to Choose?
Some of the parameters we consider while choosing a commercial refrigeration system are:
Space needs,
Storage type, and
Cost.
Let’s look into each of these in detail.
First, we need to measure the available space. Recall that commercial refrigeration systems are available in all sizes and shapes. We have to make use of the greatest possible space to maximize the commercial refrigeration system storage capacity.
There are many types of commercial refrigeration systems. One’s preferred refrigeration system depends on what type of business they are running. A shop will probably require display units, while a restaurant is more likely to require high capacity refrigerators and freezers.
The two costs we consider while buying the new commercial refrigeration system are:
Initial cost and
Operating cost.
Initial cost is the amount of money that’s needed to buy and install a new system. Operating costs generally include costs that are a direct result of the system being used.
Commercial refrigeration systems work with larger loads and for longer periods of time. Some of the businesses that require commercial refrigeration are:
Food and beverage companies,
Supermarkets,
Convenience stores, and
Restaurants.
Rack Refrigeration Systems
In this module, we will learn about rack refrigeration systems. We’ll also learn about the components of a rack refrigeration system. Skip to quiz!
Introduction
The display of food items in a supermarket is very important. Shopping for food items in a supermarket is based on instinct decisions. So it’s important that the food is presented well, and is easily accessible for customers.
All items must be presentable and readily available. However, a system should be ready to provide sufficient cooling in spite of the door of the system being opened multiple times. This calls for high cooling and a large amount of refrigerant flow in these systems.
A rack refrigeration system has multiple compressors. They all share a common source of refrigerant. All these compressors work together to create a cooling effect. These systems can maintain different temperatures in different cases.
In places like supermarkets and malls, we have to cool multiple refrigerated cases. Food items are kept in refrigerated cases and displayed. In these cases, rack refrigeration systems perform better compared to traditional refrigeration systems.
Rack refrigeration systems consist of multiple compressors. Rack refrigeration systems allow the use of multiple compressors and condenser fans for more efficient cooling. We’ll learn in detail about this system in later slides.
Components
The main components of rack refrigeration system are:
Compressors,
Condensers,
Metering devices, and
Evaporators.
Let us learn about these components in detail.
Recall that a compressor’s main job is to increase the pressure of a refrigerant. The compressor in the residential HVAC systems turns on and off to meet the set temperature value. This type of system is good for smaller cooling loads.
For larger loads, turning a single big compressor on and off is not energy efficient. Instead of one big compressor, we use multiple compressors in compressor racks. A compressor rack consists of multiple compressors that may or may not be operating at the same time.
This can be better understood with the example of a delivery truck. Instead of having a big truck deliver 100 parcels a day, we can have 10 bike riders deliver 10 parcels each. This can be better understood with the example of a delivery truck. Instead of having a big truck deliver 100 parcels a day, we can have 10 bike riders deliver 10 parcels each.
The parcels will be delivered more quickly. Similarly, the refrigerant can be delivered faster and in more quantity by multiple compressors. Also, at a time when there may be 60 parcels instead of 100 parcels, we can rest two bike riders.
Compressors in rack refrigeration systems are connected in parallel. This means that all suction lines of the compressors are connected to a single inlet, and all discharge lines of the compressors are connected to a single outlet. Multiple compressors are piped together and connected to multiple refrigerate cases.
Using multiple compressors in a rack is very useful. They operate depending on how much cooling is required. This is not the case with single compressors, in which there are only two options. Either the compressor is on or off.
Multiple compressors are useful when a supermarket stays open at night, but there are not many customers. The doors of refrigerated cases are not opened frequently overnight, and their cooling requirement is low.
Compressors are placed in a mechanical room in a remote part of a store. Mechanical rooms can be on the floor, on the roof, in the basement, or in the storage room of a supermarket.
Recall that a condenser’s main job is to cool down refrigerant. Condensers in a rack refrigeration system are usually placed on the roof or outside of a building. We generally use air-cooled type condensers in rack refrigeration systems.
Recall that a metering device’s job is to decrease the pressure of refrigerant. We use electronic expansion valves in rack refrigeration systems as metering devices. Electronic expansion valves are also called EEVs or EXVs.
EEVs can adjust refrigerant flow according to the cooling demand very quickly. Rack refrigeration systems have multiple EEVs. Every evaporator coil in a refrigerated case will have one EEV. EEVs control the flow of refrigerant in the evaporator coils of refrigerated cases.
Recall that an evaporator’s job is to absorb heat from a space in order to cool the space. In rack refrigeration systems, evaporator coils are placed inside the refrigerated cases where food is stored. Refrigerant travels through these evaporator coils to provide cooling.
Plate type evaporators are generally used in rack refrigeration systems. These evaporators are made up of two plates that are joined together. Liquid refrigerant flows through a tube made between the two plates. An evaporator cools the food items inside refrigerant cases by evaporating.
A rack refrigeration system has multiple compressors. This is called a parallel compressor system. These compressors are piped together and connected to multiple refrigerative cases.
Walk-in Refrigerators
In this module, we will learn about walk-in refrigerators. We’ll also learn about the components of a walk-in refrigerator. Skip to quiz!
Introduction
Walk-in refrigerators are very large, insulated, enclosed, box-type structures with doors large enough for people to enter. These are similar to the refrigerators you have at home, except we can walk into this one.
Some materials stored inside the walk-in refrigerators are:
Food,
Beverage,
Meat, fruits,
Vegetables,
Chemicals,
Pharmaceutical drugs.
Walk-in refrigerators provide large amounts of storage space. They make it easy for us to store large amounts of food at safe holding temperatures and prevent them from spoiling as quickly.
Walk-in refrigerators are manufactured in standard sizes, but can be customized or built into kitchens or supermarkets. They can be placed inside or outside of a building and built with or without floors.
Most walk-in refrigerators are made using insulated panels. Polyurethane insulation is sandwiched between stainless steel. Recall that polyurethane foam is commonly known as spray foam. It’s found in mattresses, home furniture, and car seats.
Identification
Walk-in refrigerators are identified by their:
size, and
temperature application.
Their size is based on the outside dimensions of length, width, and height. For example, a walk-in refrigerator is 12 feet in length, 10 feet in width, and 8 feet in height. It’s represented as 12 x 10 x 8.
Walk-in refrigerators are divided into two types based on temperature applications.
The two types of walk-in refrigerators are:
Walk-in coolers, and
Walk-in freezers.
Walk-in coolers operate above 0°C and at or below 13°C, whereas walk-in freezers operate at or below 0°C.
Food should be kept below 40°F. Higher temperatures make food spoil quickly. However, we should not set the temperature below 34°F. This might freeze items in a walk-in cooler. Freezing can ruin the texture and quality of items like dairy products.
Walk-in coolers are used to store consumable products that will be used within a few days. They’re used to store products at low temperatures above freezing temperature. We store products like fresh food, hospital medical supplies, and human remains before their funeral.
We set the temperature of walk-in freezers between 0 and -10°F for most frozen items. Walk-in freezers are used to store consumable products for months or even years.
Components
A walk-in refrigerator works on the basic refrigeration cycle.
The main components of a walk-in refrigerator are:
Compressor,
Condenser,
Metering device, and
Evaporator.
Let’s look into each of them.
Compressors and condensers of walk-in refrigerators are placed separately in a condensing box. This arrangement is similar to residential split systems. Recall that a compressor’s main job is to increase the pressure of refrigerant. Recall that a condenser’s main job is to cool down refrigerant.
Metering devices and evaporators are placed inside walk-in refrigerators near the ceiling. Recall that a metering device’s job is to decrease the pressure of refrigerant. Recall that an evaporator’s job is to absorb heat from a space in order to cool it.
A fan draws warm air inside a walk-in refrigerator onto the evaporator coils through the grille. The evaporator coils cool the air. Now cool air is circulated inside the walk-in refrigerator. This process is repeated to maintain the desired temperature inside a walk-in refrigerator.
In comfort cooling, return air entering an evaporator is about 75°F and evaporator coil temperature is about 40°F. The temperature difference between these two is about 35°F. This helps in maintaining the humidity in a room in a comfortable range by condensing the moisture in the air.
In a walk-in refrigerator, the return air entering an evaporator is about 35°F, and the evaporator coils’ temperature is about 25°F. The temperature difference between these two is about 10°F. This helps in maintaining the humidity in a walk-in refrigerator by about 85 percentage.
High humidity is very good for foods like meat. Moisture in a walk-in refrigerator prevents food from drying out. High moisture in a walk-in refrigerator reduces the evaporation of the water in food.
Walk-in refrigerators are very large, insulated, enclosed, box-type structures with access doors large enough for people to enter. Walk-in refrigerators provide large amounts of storage space. They can be placed inside or outside of a building and built with or without floors.
Walk-in refrigerators are identified by their:
size, and
temperature application.
Walk-in coolers operate above 0°C and at or below 13°C, whereas walk-in freezers operate at or below 0°C.
Ice Plants
In this module, we will learn about what an ice plant is. We’ll also learn about their components and how they work. Skip to quiz!
Introduction
People have used ice to cool foods, beverages, and other products from the earliest periods of civilization. We used natural ice in the beginning. However, artificial ice production has now become an important part of the HVAC industry.
Recall that ice is water frozen into a solid state. The demand for ice blocks is even great today. Storage, handling, and transport can be simplified if ice is made in the form of large blocks.
Ice blocks are large in size and have a small surface area, so they are not easily melted. They can be made into different forms of ice according based on the requirement.
Some industries that use ice blocks are:
Healthcare,
Hotels,
Restaurants, and
Convenience stores.
Ice blocks keep medical equipment and drugs safe, and they cool drinks and foods for future use. They’re also used to create ice sculptures.
Ice plants make ice blocks. They’re also referred to as ice machines or ice generators. The function of an ice plant is to make ice in large quantities.
Components
Ice plants work with the basic refrigeration cycle.
The main components of any ice plant are:
Compressor,
Condenser,
Metering device, and
Evaporator.
Let’s look into each of these components.
Recall that a compressor’s main job is to increase the pressure of refrigerant.
The main types of compressors used in ice plants are:
Reciprocating compressors, and
Screw compressors.
Recall that reciprocating compressors are driven by a motor, so they work similarly to an automobile engine. They are unpopular nowadays because of noise, efficiency, and maintenance issues. They are more so used in smaller capacity ice plants.
Recall that screw compressors have two shafts that are shaped like wooden screws. In these, we can have one or two screws that rotate to compress refrigerant. Screw compressors are normally used in large capacity ice plants.
Recall that a condenser’s main job is to cool down refrigerant.
The main types of condensers in ice plants are:
Fin and tube condensers,
Microchannel condensers, and
Shell and tube condensers.
Fin and tube condensers are similar to a residential air conditioner’s condenser. Generally, fins are made of aluminum, and tubes are made of copper. Hot refrigerant flows through these tubes, while fins help to cool refrigerant by distributing heat to the outside air.
Microchannel condensers are made of thin zig-zag aluminum fins. These condensers work similarly to fin and tube condensers, but are more efficient.
Shell and tube condensers consist of a series of copper tubes inside a larger shell. Water flows in the tubes, and hot refrigerant flows in the shell. Running water in the tube cools down refrigerant inside the shell. A cooling tower supplies water to shell and tube condensers.
The device used to cool hot water from a condenser is a cooling tower. Recall that cooling towers are large boxes designed to remove heat from water by spraying it down through the tower.
Recall that a metering device’s job is to decrease the pressure of refrigerant.
Ice plants mainly use two types of metering devices:
Thermal expansion valves, and
Electronic expansion valves.
Thermostatic expansion valves are also called TEV or TXV. These are used in residential HVAC systems, as well as ice plants. This controls the amount of refrigerant that flows into an evaporator based on the evaporator outlet temperature.
Electronic expansion valves are also called EEVs or EXVs. These are evolved TEVs. They provide the best performance because they are electrically operated metering devices. They allow a very accurate amount of refrigerant into an evaporator.
An evaporator’s job is to absorb heat, which provides cooling.
The types of evaporators used in ice making plants are:
Bare tube evaporators, and
Shell and tube evaporators.
Bare tube evaporators are the simplest type of evaporator. These evaporators are generally just refrigerant tubes. These evaporators are placed inside a brine tank where ice is produced.
Bare tube evaporators in ice plants are made of either copper or steel. Copper bare tube evaporators are used for small evaporators where refrigerant other than ammonia is used. Ammonia costs less but is highly toxic in nature. The leakage of ammonia can be very dangerous.
Ammonia rapidly reacts with copper tubes and forms leaks, so it is not compatible with copper. Steel bare tube evaporators are for large ice plants where ammonia is used as the refrigerant. Ammonia is compatible with steel piping.
Shell and tube evaporators are used with large capacity ice plants. Recall that shell and tube evaporators consist of a bundle of copper tubes inside a large metal shell.
In ice plants, evaporator coils are filled with refrigerant and have brine flowing over them instead of air. This is how refrigerant cools the brine.
Brine Cycle
Recall that brine is a solution formed by mixing a soluble substance in water. The soluble substance could be a salt like a table salt, calcium chloride, or glycol.
By mixing soluble substances in water, its freezing point decreases. This allows the mixing solution to remain liquid at 0ºC. Brine works as a medium that transfers the cold from refrigerant to water filled cans.
Brine tanks are usually made up of mild steel sheets with tie rods welded in the ends. Brine tanks are well insulated around the four sides and from the bottom. Brine in the tanks acts as a medium of contact. The temperature of brine in tanks is maintained at about -10°C to -110°C.
Ice cans are made up of galvanized steel, and a chromium layer is applied to prevent corrosion. Ice cans are filled with fresh water and kept in a brine tank. Brine is cooled by refrigerant, which in turn cools the water in the cans.
People have used ice to cool foods, beverages, and other products from the earliest periods of civilization. Storage, handling, and transport can be simplified if ice is made in the form of large blocks. The function of an ice plant is to make ice in large quantities.
Ice plants also work with the basic refrigeration cycle. Brine tanks are usually made up of mild steel sheets with tie rods welded in the ends. Brine is cooled by refrigerant, which in turn cools the water in the cans.
Question #1: Where can we find commercial refrigeration systems? (Select all that apply)
Supermarkets
Convenience stores
Food companies
All the above
Scroll down for the answer...
Answer: All the above
Some businesses that require commercial refrigeration are:
Food and beverage companies,
Supermarkets,
Convenience stores, and
Restaurants.
Question #2: Which of the following are commercial refrigeration systems? (Select all that apply)
Rack refrigeration systems
Window air conditioners
Walk-in refrigerators
Water softener
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Answer: Rack refrigeration systems
Walk-in refrigerators
The main commercial refrigeration systems that find are:
Rack refrigerators,
Walk-in coolers, and
Ice plants.
Question #3: Which of the following parameters do we consider while choosing a commercial refrigeration system? (Select all that apply)
Storage type
Cost of the system
Space needs
All the above
Scroll down for the answer...
Answer: All the above
Some of the parameters we consider while choosing a commercial refrigeration system are:
Space needs,
Storage type,
Cost, and
Brand names.
Question #4: How many compressors does a rack refrigeration system consist of?
One
Two
Four
Multiple
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Answer: Multiple
Rack refrigeration systems consist of multiple compressors.
Question #5: In a rack refrigeration system, compressors are connected in _______.
series
parallel
circular
square
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Answer: parallel
In a rack refrigeration system, compressors are connected in parallel.
Question #6: In a rack refrigeration system, compressors are placed in a _______.
Mechanical room
Civil room
Storage room
Drawing room
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Answer: Mechanical room
In a rack refrigeration system, compressors are placed in a mechanical room.
Question #7: Which of the following types of condensers are used in rack refrigeration systems?
Air-cooled condensers
Water-cooled condensers
Refrigerant-cooled condensers
Brine-cooled condensers
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Answer: Air-cooled condensers
Air-cooled condensers are used in rack refrigeration systems.
Question #8: Which of the following metering devices is usually found in rack refrigeration systems?
Capillary tube
Thermal expansion valve
Electronic expansion valve
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Answer: Electronic expansion valve
We use electronic expansion valves in rack refrigeration systems as metering devices.
Question #9: Which components are placed in the refrigerated cases in the rack refrigeration system?
Compressors
Condenser coils
Evaporator coils
Electronic expansion valves
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Answer: Evaporator coils
In rack refrigeration systems, evaporator coils are placed inside the refrigerated cases where food is stored.
Question #10: Which of the following refrigeration systems provide large amounts of storage space?
Residential refrigerator
Walk-in refrigerator
Top freezer refrigerator
French door refrigerator
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Answer: Walk-in refrigerator
Walk-in refrigerators provide large amounts of storage space.
Question #11: Which of the following insulation materials is sandwiched in between walk-in refrigerator panels?
Wood
Glass fiber
Polyurethane
Cellular glass
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Answer: Polyurethane
Most walk-in refrigerators are made using fabricated panels. Polyurethane insulation is sandwiched between stainless steel.
Question #12: Walk-in refrigerators are divided into walk-in freezers and walk-in coolers based on the ______
volume of airflow
temperature application
size of it
number of doors
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Answer: temperature application
Walk-in refrigerators are divided into walk-in freezers and walk-in coolers based on temperature application. Walk-in coolers operate above 0°C and at or below 13°C, whereas walk-in freezers operate at or below 0°C.
Question #13: Which of the following components are placed inside walk-in refrigerator? (Select all that apply)
Compressor
Metering device
Evaporator
Condenser
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Answer: Metering device
Evaporator
The metering device and evaporator are placed inside walk-in refrigerator near the ceiling.
Question #14: What is the approximate humidity we maintain in a walk-in refrigerator?
10%
25%
50%
85%
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Answer: 85%
We maintain humidity in a walk-in refrigerator at about 85 percentage. This high humidity keeps food from drying out.
Question #15: Which of the following are benefits of large ice blocks?
Storage
Handling
Transport
All the above
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Answer: All the above
Storage, handling, and transport can be simplified if ice is made in the form of large blocks.
Question #16: Which of the following refrigeration systems are used for making ice?
Walk-in coolers
Ice plants
Rack refrigeration systems
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Answer: Ice plants
Ice plants are used to produce ice.
Question #17: Ice plants are used to produce ice in _______ quantities.
small
medium
large
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Answer: large
Ice plants are used to produce ice in large quantities.
Question #18: Which of the following types of refrigerant compressors are generally used in ice plants? (Select all that apply)
Reciprocating compressors
Scroll compressors
Screw compressors
Centrifugal compressors
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Answer: Reciprocating compressors
Screw compressors
The main types of compressors used in ice plants are:
Reciprocating compressors, and
Screw compressors.
Question #19: Which of the following types of condensers are connected with cooling towers?
Fin and tube condensers
Shell and tube condensers
Microchannel condensers
Spine fin condensers
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Answer: Shell and tube condensers
Shell and tube condensers are connected with cooling towers. Cooling towers supply water to cool down refrigerant in the condenser.
Question #20: Which of the following metal evaporators is used with ammonia as the refrigerant?
Copper
Steel
Aluminum
Gold
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Answer: Steel
Steel evaporators are used with ammonia as a refrigerant. Ammonia is compatible with steel piping.
Question #21: Ice cans are filled with _______ and kept in a brine tank.
Refrigerant
Brine
Water
Petrol
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Answer: Water
Ice cans are filled with fresh water and kept in a brine tank.
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