ClassX Video Lessons Youtube Channel The Engineering Mindset Industrial Refrigeration system Basics – Ammonia refrigeration working principle
Welcome to an exploration of industrial refrigeration systems, with a focus on ammonia-based systems. This article will guide you through the fundamentals and typical configurations, including single-stage, two-stage, and cascade systems, to enhance your understanding of industrial refrigeration.
Ammonia is a popular choice for industrial refrigeration due to its natural abundance and environmental benefits. It has an ozone depletion potential of zero and a global warming potential of less than one, making it a more sustainable option compared to other refrigerants like R134A and R404A. Ammonia is also cost-effective and energy-efficient, capable of absorbing significant amounts of heat during evaporation, which is essential for effective refrigeration. However, it is important to note that ammonia is toxic and can be flammable at certain concentrations. Its distinct sour smell helps in detecting leaks, which react with air to form harmless ammonium bicarbonate.
Industrial refrigeration systems are commonly found in sectors such as cold food storage, dairy processing, beverage production, ice rinks, and heavy industry. These systems are large-scale and differ from commercial building cooling systems. Let’s delve into the engineering aspects of these systems.
The single-stage system is the simplest form of ammonia refrigeration. It begins with a compressor, which circulates the ammonia refrigerant to provide cooling. The compressor draws in low-pressure vapor refrigerant from the evaporator, compresses it, and transforms it into high-pressure vapor. This vapor then moves to the condenser, where it releases heat to the surrounding air, aided by fans or water sprays. The refrigerant condenses into a liquid and is stored in the receiver, which balances pressure and accommodates varying cooling loads. The liquid refrigerant then passes through an expansion valve into the evaporator, where it absorbs heat from the surrounding air, cooling it. The cycle repeats as the refrigerant returns to the compressor.
The two-stage system is designed for low-temperature applications, offering high efficiency and reduced compressor discharge temperatures. It includes an intermediate cooler between the receiver and expansion valve. The refrigerant is cooled in this intermediate stage before reaching the main expansion valve. A low-stage compressor increases the pressure of vapor refrigerant, which then condenses in the intermediate cooler before proceeding to the high-stage compressor and condenser.
The cascade system is the most complex, suitable for applications requiring varied temperature ranges. It consists of two or more separate refrigeration circuits, often using different refrigerants. A cascade condenser connects the circuits, acting as a condenser for the high-temperature circuit and an evaporator for the low-temperature circuit. This setup allows for optimized efficiency, with ammonia potentially used for the high-temperature side and CO2 for the low-temperature side.
Understanding the intricacies of ammonia refrigeration systems is crucial for their effective application in industrial settings. These systems offer environmentally friendly and efficient solutions for large-scale cooling needs. For further learning, consider exploring additional resources and courses on ammonia refrigeration.
Engage with an online simulation tool that allows you to manipulate different components of ammonia refrigeration systems. Experiment with single-stage, two-stage, and cascade systems to observe how changes affect system performance. This hands-on activity will deepen your understanding of system dynamics and component interactions.
Analyze real-world case studies of industrial facilities using ammonia refrigeration systems. Identify the benefits and challenges faced in each scenario. Discuss in groups how the principles you’ve learned apply to these cases and propose potential improvements or alternatives.
Participate in a workshop where you design a basic ammonia refrigeration system for a hypothetical industrial application. Consider factors such as efficiency, environmental impact, and safety. Present your design to peers and receive feedback to refine your understanding and approach.
Work in teams to develop a comprehensive safety protocol for handling ammonia in industrial refrigeration systems. Focus on leak detection, emergency response, and maintenance procedures. This activity will enhance your awareness of safety considerations and regulatory compliance.
Conduct an environmental impact assessment comparing ammonia refrigeration systems to other refrigerants like R134A and R404A. Evaluate factors such as global warming potential, ozone depletion, and energy efficiency. Present your findings in a report, highlighting the sustainability advantages of ammonia.
Here’s a sanitized version of the provided YouTube transcript:
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Hello everyone, Paul here from TheEngineeringMindset.com. In this video, we will explore the basics of industrial refrigeration systems, focusing specifically on ammonia refrigeration systems. We’ll start with the fundamentals and progress to typical systems, including single-stage, two-stage, and cascade systems, to help you understand industrial refrigeration.
I want to take a moment to thank our partner, Danfoss, for sponsoring this video. Danfoss is dedicated to sharing knowledge about modern, environmentally-friendly refrigerants, including ammonia and its applications in industrial refrigeration solutions. They offer a collection of free ammonia eLessons available now at Danfoss Learning. You can find the link in the video description below to start your first course.
So, where are these systems typically found? Industrial refrigeration applications are commonly used in cold food storage, dairy processing, beverage production, ice rinks, and heavy industry. These are large-scale cooling systems. We have previously discussed other types of cooling systems for commercial buildings, such as supermarket CO2 systems, chillers, and chilled water schematics. Be sure to check those out if you haven’t already; links are in the video description below.
Now, let’s briefly discuss why ammonia is used as a refrigerant. Ammonia occurs naturally in the environment and is abundant. It has an ozone depletion rating of zero and a global warming potential of less than one. In comparison, other common refrigerants like R134A have a GWP of 1,430, and R404A has a GWP of 3,922. This highlights the benefits of using ammonia. Additionally, ammonia is cost-effective to produce and energy-efficient. It can absorb large amounts of heat as it evaporates, which is crucial for a refrigerant’s effectiveness. This property allows for thinner and smaller pipes and components.
However, ammonia is toxic and can be flammable at certain concentrations. Unlike most refrigerants, which are odorless, ammonia has a distinct sour smell, making leaks easily detectable. If ammonia leaks, it reacts with carbon and water in the air to form ammonium bicarbonate, a harmless compound.
Now, let’s dive into the engineering aspects. We’ll start with a simplified overview of typical refrigeration systems.
**Single Stage System:** This is the simplest ammonia industrial refrigeration system, aside from a direct expansion type. The system begins with the compressor, which is the heart of the system, pumping the ammonia refrigerant throughout to provide cooling. It pulls in refrigerant that has absorbed unwanted heat from the evaporator and compresses it into a smaller volume, increasing its temperature. The refrigerant enters the compressor as a low-pressure vapor and exits as a high-pressure vapor.
The high-pressure vapor then flows to the condenser, which cools the refrigerant by removing unwanted heat and discharging it into the ambient air. This is typically achieved by passing the hot refrigerant through small tubes while a fan blows cooler air across the tubes to carry the heat away. Sometimes, a small pump sprays water over the pipes to enhance heat removal through evaporation.
The refrigerant is contained within the pipes and does not mix with air or water; only the heat passes through the pipe walls. As heat is removed, the refrigerant condenses into a liquid and exits the condenser as a high-pressure liquid, flowing to the receiver. The receiver acts as a storage vessel for liquid refrigerant, maintaining a minimum head pressure and accommodating varying cooling loads.
A line usually connects the receiver to the condenser inlet for pressure equalization, allowing liquid refrigerant to flow more easily from the condenser to the receiver. The refrigerant then moves to the expansion valve, which regulates the pressure and flow of liquid refrigerant into the evaporator circuit.
From the expansion valve, the refrigerant flows into the liquid separator, where the liquid is drawn in by refrigerant pumps that ensure proper circulation through the evaporators as cooling loads change. The cold refrigerant enters the evaporator, where it absorbs heat from the warm room air blown across the outside of the evaporator pipes. This process cools the air, which leaves the space at a lower temperature.
As the warm air passes over the evaporator pipes, it causes the ammonia to boil and evaporate, carrying heat away. The refrigerant exits the evaporator as a liquid/vapor mixture and returns to the liquid separator. The liquid refrigerant falls down and repeats the cycle, while the vapor rises and is drawn back into the compressor to start the process again.
**Two Stage System:** This is an advanced version of the industrial refrigeration system, suitable for low-temperature applications, providing high efficiency and low compressor discharge temperatures. The refrigerant follows a similar cycle but includes additional components. An intermediate cooler is situated between the receiver and the expansion valve. The main flow of refrigerant passes through a coil inside the tank, cooling the refrigerant before it reaches the main expansion valve.
Another stream of refrigerant is sprayed into the tank via an expansion valve, producing a cooling effect that sub-cools the main flow. The vapor refrigerant is drawn out of the separator and sent to a low-stage compressor to increase pressure. It then flows to the intermediate cooler to condense before moving to the high-stage compressor and back to the condenser.
**Cascade System:** This is the most advanced and complex system, suitable for applications requiring different temperature ranges. It simplifies compliance with health, safety, and environmental regulations. These systems typically consist of two or more separate refrigeration circuits, often using different refrigerants.
In this setup, there are two compressors circulating refrigerant in separate circuits: a high-temperature circuit and a low-temperature circuit. A heat exchanger, known as a cascade condenser, connects the two circuits. The cascade condenser acts as a condenser for the high-temperature circuit and as an evaporator for the low-temperature circuit. The refrigerants can be the same or different, optimized for each circuit. For instance, ammonia could be used for the high-temperature side and CO2 for the low-temperature side, enhancing efficiency.
I want to thank Danfoss again for sponsoring this video. Don’t forget to check out their free ammonia eLessons by clicking the link in the video description below.
That’s it for this video! If you want to continue learning about refrigeration systems, click on one of the videos on screen now, and I’ll see you in the next lesson. Feel free to leave your questions in the comments, and don’t forget to follow us on Facebook, Instagram, Twitter, and at TheEngineeringMindset.com.
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This version removes any informal language and ensures clarity while maintaining the original content’s educational value.
Ammonia – A colorless gas with a characteristic pungent smell, used as a refrigerant in industrial refrigeration systems due to its high energy efficiency and low environmental impact. – Ammonia is commonly used in large-scale refrigeration systems because it offers excellent thermodynamic properties and is environmentally friendly compared to other refrigerants.
Refrigeration – The process of removing heat from a space or substance to lower its temperature, often used in preserving perishable goods and in air conditioning systems. – The refrigeration cycle involves the absorption of heat from the interior of a refrigerator and its expulsion to the environment, maintaining a cool temperature inside.
Systems – Integrated sets of components or devices that work together to perform a specific function, often used in engineering to refer to complex assemblies like HVAC systems or electrical grids. – Engineers must design systems that efficiently integrate mechanical and electrical components to ensure optimal performance and reliability.
Compressor – A mechanical device that increases the pressure of a gas by reducing its volume, commonly used in refrigeration and air conditioning systems to circulate refrigerant. – The compressor in an air conditioning unit is responsible for compressing the refrigerant, which then flows through the system to absorb and dissipate heat.
Evaporator – A component in refrigeration systems where the refrigerant absorbs heat and evaporates, cooling the surrounding environment. – The evaporator coil in a refrigerator is where the refrigerant absorbs heat from the interior, causing it to evaporate and cool the space.
Condenser – A device used in refrigeration systems to condense refrigerant vapor into liquid by removing heat, typically located outside the cooled area. – The condenser releases the absorbed heat from the refrigerant to the outside environment, allowing it to return to a liquid state.
Cooling – The process of lowering the temperature of an environment or substance, often achieved through refrigeration or air conditioning systems. – Effective cooling is essential in data centers to prevent overheating of servers and other critical equipment.
Efficiency – A measure of how well a system or component converts input energy into useful output, often expressed as a percentage. – Improving the efficiency of a refrigeration system can significantly reduce energy consumption and operational costs.
Temperature – A measure of the average kinetic energy of particles in a substance, indicating how hot or cold the substance is. – Maintaining a stable temperature is crucial in chemical processes to ensure consistent reaction rates and product quality.
Circuits – Closed paths through which electric current flows, consisting of various electrical components such as resistors, capacitors, and inductors. – Engineers design circuits to control the flow of electricity and perform specific functions in electronic devices.
