Blog - Page 14 of 50 - MEP Academy

Air Distribution for Large Area’s

HVAC Systems

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August 4, 2023

Air Distribution for large area’s. Commercial and industrial applications where efficient air distribution and high air flow rates are required these diffusers are designed to handle large volumes of air and are suitable for spaces with high ceilings or areas that demand significant ventilation cooling or heating.

If you prefer to watch the video of this presentation, then scroll to the bottom or click on the following link. Air Distribution for Large Area’s

We’ll first look at those factors that affect the throw distance of a jet diffuser.

In this chart the throw distance for a ceiling mounted jet diffuser is shown for isothermal conditions, that is where the temperature of the air leaving the diffuser and the room temperature are basically the same.

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Vertical throw Distance for Different Temperature Air.

The vertical throw is 27 feet. If the air was colder than the ambient air by 20 degrees Fahrenheit it would reach 38 feet, which is much greater than an isothermal conditions. If the air was in heating mode and was 40 degrees Fahrenheit greater than the ambient air, then our throw distance would be shortened to 12 feet. it’s important to know the effects of location on the throw.

In this chart using one manufacturer’s data for jet diffusers, the angle of throw is shown to affect the distance. At 0 degrees the air will be thrown 84 feet. If the angle of the air is changed to 22 degrees, then the air will only achieve 59 feet of distance. By increasing the angle again to 45 degrees, the air will spread out wider and throw at half the distance of that at 0 degrees, giving a total distance of 42 feet.

Check the manufacturer’s literature for correction factors to the listed performance values, as the charts can be based on isothermal conditions, 0 degrees of deflection, whether there is a ceiling, and the distance of the diffuser below the ceiling. Also affected by deflection is pressure drop. As the angle of deflection is increased, so is the pressure dropped through the jet diffuser.

Correction Factors for Vertical Throw. Notice the reduction in throw as the temperature increases over ambient. Ref. KOO

In the chart below the relationship between velocity, drop, and throw distance are compared. This scenario will be different per manufacturer, diffuser location, deflection angles and whether there is a ceiling. This example is intended to get you thinking about the factors that are important to consider.

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At a velocity of 100 feet per minute the air will drop 3 feet and reach 12 feet in distance. At a velocity of 500 feet per minute, the air will drop 7 feet, with a throw of 20 feet. At a velocity of 1000 feet per minute the air will drop 6 feet and reach 30 feet in throw distance. And finally with the velocity of 1500 feet per minute, the air drops 5 feet, and reaches 35 feet in distance. The greater the velocity, the greater the throw distance.

Drop and Throw Distances based on different Velocities.

The throw distance is affected by the location of the ceiling as shown in this chart. We now have what is called the Coanda effect, the tendency of the air to follow the adjacent ceiling surface, allowing for greater throw distances. Now with a velocity of 100 FPM the air only drops 1 foot but reaches 19 feet. At 500 FPM, the drop is 8 feet with a 28-foot distance. At 1000 FPM, the air drops 7 feet and reaches 42 feet, and finally a velocity of 1500 FPM sees the air drop 6 feet with a throw of 50 feet.

What we learned here is that the throw distance is affected by many factors including location, angle of throw, velocity, and whether there is a ceiling.

High-Capacity Airflow Diffusers

Some common locations where high-capacity air diffusers are used include:

1. Airports: In large airport terminals, high-capacity diffusers like jet diffusers are often used to efficiently distribute conditioned air over long distances and maintain comfortable indoor environments for travelers and staff.

Museums with large open areas can benefit from in-depth engineering review of air distribution strategies

2. Museums and Exhibition Halls: These spaces often have high ceilings and require precise air distribution to preserve artworks and artifacts. High-capacity diffusers with long throw capabilities and adjustable airflow patterns are commonly employed in these settings.

3. Theaters and Auditoriums: Venues with a large seating capacity, like theaters and auditoriums, need effective airflow distribution to ensure the comfort of the audience. High-capacity diffusers help maintain consistent temperatures and air quality throughout these spaces.

4. Large Retail Stores: In big-box retail stores or shopping malls, where the open layout and high ceilings can lead to challenges in uniform air distribution, high-capacity diffusers are utilized to achieve proper ventilation and cooling.

Convention Centers and Large Exhibition Centers

5. Convention Centers: Convention centers often host large gatherings and events, and high-capacity diffusers are used to handle the substantial airflow requirements in these vast spaces.

6. Industrial Facilities: Certain industrial facilities require high-capacity ventilation and air distribution to control temperature, humidity, and air quality. High-capacity diffusers are used in these settings to maintain the desired environmental conditions.

Checkout these Jet Diffusers here

7. Gyms and Sports Facilities: Spaces with high occupant density and intense physical activities can benefit from high-capacity diffusers to ensure efficient ventilation and cooling.

Large capacity air diffusers work and are an essential part of efficient HVAC systems in various commercial and industrial settings. These diffusers are designed to handle high airflow rates and distribute conditioned air effectively in large open spaces. They play a crucial role in maintaining thermal comfort, indoor air quality, and energy efficiency.

Various Styles of Air Distribution

Styles of high-capacity airflow diffusers can vary based on their design, installation method, and intended application. Some common styles include:

1. Jet Diffusers: The primary purpose of a jet diffuser is to deliver a high-velocity jet of air over long distances. The diffuser’s design should ensure a sufficient throw distance to reach the desired target areas within the space effectively. Some jet diffusers have adjustable nozzles or vanes, allowing users to modify the direction and spread of the airflow. This adjustability is valuable for optimizing the air distribution pattern based on specific room layouts and occupancy changes. They are available in various configurations, including round, rectangular, and linear designs.

Here is the performance table of a Ring Nozzle Diffuser. We can see when the size of the diffuser gets larger, so does the diffusers ability to handle more CFM and throw the air much further.

With a duct velocity of 1,000 feet per minute, 8-inch diffusers can provide 349 CFM and a throw of 24 feet maximum, while a 16-inch diffuser can handle 1,396 CFM with a throw of 48 feet maximum, four times the CFM, and twice the distance.

2. Linear Slot Diffusers: Linear slot diffusers provide a long, continuous opening for air distribution. They are available in various lengths and configurations, making them suitable for many different applications.

3. Displacement Ventilation Systems: These systems are designed to supply conditioned air at low velocities near the floor level without significant induction of room air. The cooler supply air forms a stable, stratified layer that displaces the warmer air upward, resulting in a distinct separation of supply and room air, allowing the warm air to rise, and be expelled at the ceiling. These can be used in a raised floor system for office spaces, or in high traffic public areas like airports these systems will be hidden in architectural features like the ticketing or baggage check-in counter, or under an escalator. The diffusers will blend in with the overall aesthetics and to avoid visual disruptions. See our video on Underfloor Air Distribution.

4. Induction Displacement Diffusers: Induction displacement diffusers supply conditioned air at low velocities near the floor level, inducing room air into the supply air stream. The entrainment of room air creates a mixed supply air stream, which then rises and displaces the warmer air at the ceiling level.

5. Fabric Ducts: Fabric ducts are flexible, porous ducting systems that allow for even air distribution along the entire length of the duct. They come in various colors and shapes and can be integrated into the architectural design of the space.

6. Underfloor Air Distribution Diffusers: Under floor diffusers are installed beneath raised floors and deliver conditioned air upward through floor diffusers. Displacement diffusers should have the ability to supply air at low velocities near the floor level to achieve stratification and induce room air into the supply air stream. They are commonly used in office spaces and other commercial buildings.

The specific style of high-capacity air diffusers used in a particular setting depends on factors such as the HVAC system design, architectural requirements, and the desired air distribution pattern for the space.

Designing Air Distribution for Large Area’s

Designing a large capacity airflow ventilation and cooling system for an airport terminal requires a systematic approach to ensure efficiency, comfort, and safety. The following steps outline a general process for designing such a system:

1. Gather Design Requirements: Start by gathering all the design requirements and specifications for the airport terminal. Consider factors such as the total floor area, occupancy levels, expected peak passenger loads, indoor air quality targets, thermal comfort requirements, and any specific architectural constraints.

2. Perform Site Survey and Analysis: Conduct a detailed site survey of the airport terminal to understand the building’s layout, ceiling height, existing HVAC infrastructure, and any potential challenges or unique characteristics. This information will help shape the design strategy.

3. Load Calculation: Perform a thorough load calculation to determine the heating and cooling requirements of the terminal space. This involves considering heat gains from lighting, equipment, passengers, solar radiation, and external weather conditions.

4. Air Distribution Strategy Selection: Choose the appropriate air distribution strategy for the terminal. Consider options like jet diffusers, linear slot diffusers, displacement ventilation, underfloor air distribution, or a combination of different methods based on the specific requirements of different zones within the terminal.

5. Ductwork Design: Design the ductwork layout to ensure efficient airflow distribution. Proper sizing and routing of ducts are essential to minimize pressure losses and achieve the desired airflow rates in different areas of the terminal.

6. Equipment Selection: Select the appropriate HVAC equipment, including air handling units (AHUs), chillers, cooling towers, pumps, and fan coils, to meet the cooling and ventilation demands of the airport terminal. Ensure the equipment is capable of handling the required air volumes and cooling loads.

7. Integration of Sustainable Features: Explore opportunities for incorporating sustainable features, such as energy-efficient HVAC equipment, demand-based ventilation controls, waste heat recovery, and renewable energy sources, to optimize energy efficiency and reduce operational costs.

8. Computational Fluid Dynamics (CFD) Analysis: Conduct CFD simulations to analyze the airflow patterns, temperature distribution, and indoor air quality within the terminal space. This analysis helps validate the design and fine-tune the system for optimal performance.

9. Emergency Scenario Planning: Plan for emergency scenarios, such as smoke control and evacuation, by designing specific ventilation strategies to handle such situations effectively and ensure the safety of occupants.

10. Controls and Automation: Design a comprehensive control system that allows for precise temperature and airflow adjustments based on occupancy levels, weather conditions, and other variables. Implement smart controls for efficient operation and easy monitoring of the HVAC system.

11. Installation and Commissioning: Oversee the installation of the ventilation and cooling system by qualified contractors. After installation, commission the system to ensure it functions according to the design specifications and meets performance criteria.

12. Testing and Balancing: Perform thorough testing and balancing of the HVAC system to verify that it delivers the intended airflow rates and temperature conditions throughout the terminal.

13. Ongoing Maintenance and Monitoring: Implement a comprehensive maintenance plan to ensure the continuous optimal performance of the HVAC system. Regular monitoring and fine-tuning of the system will help identify and address any performance issues promptly.

Throughout the design process, collaboration between mechanical engineers, architects, HVAC specialists, and other relevant stakeholders is essential to create a successful, efficient, and comfortable airflow ventilation and cooling system for the airport terminal.

Key Considerations for Designing Large Open Area’s

Designing a ventilation and cooling system for very large open areas in buildings like airport terminals requires careful consideration of several special requirements to ensure effective air distribution, thermal comfort, and energy efficiency. Some of the key special requirements for such systems include:

1. High Airflow Capacity: The system must be capable of handling a high airflow rate to provide adequate ventilation and cooling for the large volume of air present in airport terminals. This may involve the use of high-capacity air diffusers, powerful air handling units, and appropriately sized ductwork.

2. Long Throw Distance: Due to the vast spaces in airport terminals, the air distribution system must be designed to achieve long throw distances. Jet diffusers, linear slot diffusers, and other devices with strong throw capabilities are often employed to deliver conditioned air effectively to distant areas.

3. Induction and Mixing: To prevent temperature stratification and ensure even cooling throughout the terminal, the system should promote air mixing and induction. High-induction diffusers, displacement ventilation, and properly located supply and return vents contribute to effective mixing.

4. Zoning and Control: Implementing zoning and precise control over the ventilation and cooling system is crucial for large spaces with varying occupancy levels. Using sensors, occupancy-based controls, and demand-controlled ventilation can optimize energy usage and maintain comfort levels in different zones.

5. Air Quality Management: Managing indoor air quality is essential in high-occupancy areas like airport terminals. The system should incorporate appropriate filtration, humidity control, and the capability to efficiently exhaust contaminated air from specific areas (e.g., restrooms, smoking lounges).

6. Air Distribution Flexibility: The design should allow for flexibility in air distribution to adapt to changing needs or building modifications. Adjustable diffusers, fabric ducts, or other flexible air distribution solutions can help achieve this flexibility.

7. Noise Reduction: Large airports can be noisy environments, and the ventilation system should be designed to minimize additional noise generation. Acoustic design considerations, proper equipment selection, and noise-reduction features in diffusers and ducts can contribute to a quieter terminal environment.

8. Energy Efficiency: Given the scale of airport terminals, energy-efficient design and equipment selection are critical to reduce operational costs and environmental impact. Incorporating energy-efficient HVAC components, demand-based controls, and waste heat recovery can contribute to energy savings.

9. Emergency Scenarios: The ventilation system must also be designed to handle emergency scenarios such as fire incidents or hazardous material releases. Smoke control systems and emergency ventilation strategies should be integrated into the overall design.

10. Maintenance Accessibility: Large open spaces can be challenging to access for maintenance and servicing. The system design should consider easy access to equipment, diffusers, and ducts to ensure efficient maintenance and repair operations.

Designing a ventilation and cooling system for very large open areas like airport terminals requires a comprehensive approach that addresses high airflow capacity, long throw distances, air mixing, control, air quality management, energy efficiency, noise reduction, emergency scenarios, and maintenance accessibility. A well-designed system ensures a comfortable and safe environment for passengers and staff while minimizing operating costs.

Why large capacity air diffusers work effectively:

1. High Airflow Handling: Large capacity air diffusers are specifically designed to accommodate significant volumes of air. This allows them to deliver substantial amounts of conditioned air into the space, ensuring adequate ventilation and cooling/heating as required.

2. Long Throw Distance: Many large capacity diffusers, like jet diffusers, are capable of achieving long throw distances. They can project the air jet over considerable distances without losing much momentum, making them suitable for high-ceiling areas and large open spaces.

3. Effective Air Distribution: These diffusers are engineered to create well-defined and targeted airflow patterns. Whether it’s through jet nozzles, fabric ducts, or displacement ventilation, the designs are optimized for efficient air distribution throughout the space, avoiding hotspots and ensuring even temperatures.

4. Coanda Effect and Induction: Jet diffusers and other high-capacity diffusers often utilize the Coanda effect and induction principle. The Coanda effect encourages the air jet to adhere to nearby surfaces, and induction helps mix the supplied air with room air, ensuring better air mixing and distribution.

5. Improved Indoor Air Quality: Adequate ventilation provided by large capacity diffusers helps maintain good indoor air quality by supplying fresh air and removing airborne contaminants.

6. Energy Efficiency: Efficient air distribution minimizes the need for over-conditioning, leading to energy savings. Some diffusers, like displacement ventilation and underfloor air distribution, promote energy efficiency by delivering conditioned air where it’s needed most.

7. Flexibility and Control: Many large capacity diffusers come with adjustable features that allow users to customize the direction and spread of the airflow. This flexibility helps optimize air distribution based on room layouts and occupancy patterns.

8. Integration with HVAC Systems: These diffusers are integrated into HVAC systems, ensuring proper coordination with other components like air handlers, ductwork, and exhaust systems.Overall, large capacity air diffusers are an effective solution for maintaining comfortable and healthy indoor environments in spaces like airports, exhibition halls, auditoriums, and other large open areas. Their design and performance are crucial for providing appropriate ventilation, cooling, and heating while supporting energy-efficient HVAC operations.

Computational Fluid Dynamics

Computational Fluid Dynamics (CFD) is a powerful tool that can be used to improve the performance of airflow design for airport terminals or large open spaces. CFD simulations enable engineers to model and analyze the behavior of airflows within the terminal space, providing valuable insights for optimizing the airflow design.

Here are some ways CFD can be utilized to enhance airflow design in airport terminals:

1. Airflow Visualization: CFD allows engineers to visualize the airflow patterns within the terminal, helping to identify areas of stagnation, recirculation, or inadequate ventilation. This information is crucial for understanding the overall airflow distribution and identifying potential issues that might impact thermal comfort and indoor air quality.

2. Thermal Comfort Analysis: With CFD simulations, engineers can assess the thermal comfort of passengers and staff by studying the temperature distribution throughout the terminal. This analysis helps identify regions with potential thermal discomfort and aids in optimizing the HVAC system to achieve uniform thermal conditions.

3. Air Quality Assessment: CFD can predict the dispersion of pollutants, contaminants, or airborne pathogens within the terminal space. This assessment is critical for maintaining a healthy indoor environment and designing an efficient ventilation system to remove pollutants effectively.

4. Jet Diffuser Performance: CFD can be used to evaluate the performance of jet diffusers or other specialized diffusers in distributing conditioned air over long distances. Engineers can analyze the effectiveness of diffuser placement, direction, and velocity profiles to achieve the desired airflow throw and distribution.

5. HVAC System Optimization: CFD simulations can help optimize the placement and capacity of air handling units, supply and return vents, and ductwork. By assessing different configurations and scenarios, engineers can identify the most energy-efficient and effective HVAC system design for the terminal.

6. Zoning and Airflow Balancing: CFD can assist in determining the optimal zoning of the terminal for efficient airflow distribution based on occupancy levels and thermal loads. Engineers can analyze various scenarios to balance the airflow in different areas, ensuring all zones receive adequate conditioned air.

7. Emergency Scenario Analysis: CFD simulations can also be used to model emergency scenarios, such as smoke dispersion in case of fire incidents. This analysis helps in designing effective smoke control systems and emergency ventilation strategies to ensure the safety of passengers and staff.

8. Design Validation and Troubleshooting: CFD can be used to validate the effectiveness of the airflow design before implementation. It allows engineers to troubleshoot potential issues, make informed design decisions, and optimize the design for peak performance.

By leveraging CFD simulations, engineers can gain a comprehensive understanding of the airflow behavior in airport terminals and make data-driven decisions to enhance thermal comfort, indoor air quality, and energy efficiency. This results in a better-designed ventilation system that meets the specific requirements of the terminal while providing a comfortable and safe environment for all occupants.

Air Distribution for Large Area’s

Water Treatment Point-of-Use Filters

Plumbing

MEP Academy Instructor

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July 26, 2023

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Water Treatment Point-of-Use Filters. This is the first article in our series on the methods of water treatment for both the home and office. Access to clean and safe drinking water is a fundamental human right, yet water quality issues continue to be a concern in many regions.

If you prefer to watch the video version of this presentation than scroll to the bottom or click on the following link. Water Treatment Point-of-Use Filters

Point-of-Use filters have emerged as a convenient and effective solution to address this challenge. These innovative filters provide a simple but powerful means to purify water directly at the point of consumption, ensuring every drop you drink is free from contaminants. In this article, we explore the benefits and applications of Point-of-Use filters, and why they are becoming an indispensable tool for water treatment at home or at the office.

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What Are Point-of-Use Filters?

Point-of-Use filters are compact devices designed to remove impurities from water at the specific point where it is consumed, such as kitchen sinks, faucets, or water dispensers. They are available in various forms, including faucet-mounted filters, countertop filters, under-sink systems, and pitcher filters. Each type offers unique advantages, catering to different user preferences and installation requirements. Checkout the latest Filters and their Pricing

How Do Point-of-Use Filters Work?

Most Point-of-Use filters use a combination of filtration technologies to effectively remove contaminants from water. Common methods include:

1. Activated Carbon Filtration: This technique involves using activated carbon to adsorb and trap contaminants like chlorine, volatile organic compounds (VOCs), pesticides, and bad tastes and odors.

2. Reverse Osmosis (RO) Filtration: RO filters employ a semi-permeable membrane to remove a wide range of impurities, including dissolved solids, heavy metals, fluoride, and bacteria.

Point of Use Filter Materials and Methods

3. Ceramic Filtration: Ceramic filters have fine pores that can physically block larger particles, sediments, and bacteria.

4. UV Sterilization: UV filters use ultraviolet light to neutralize bacteria, viruses, and other microorganisms present in the water.

We’ll cover each of these different methods of water treatment in the following videos of this series.

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Applications of Point-of-Use Filters:

1. Drinking Water: The most common application is for purifying drinking water, ensuring that your family consumes safe and clean water every day.

2. Cooking: Using filtered water in food preparation enhances the taste and quality of meals.

3. Beverage Making: Whether it’s making tea, coffee, or smoothies, using filtered water can significantly enhance the final product.

4. Baby Formula: Point-of-Use filters are especially beneficial for preparing baby formula, providing infants with the purest water possible.

Choosing the Right Point-of-Use Filter:

When selecting a Point-of-Use filter, consider factors such as your local water quality, filter type, filter life, maintenance requirements, and certifications. Look for filters certified by reputable organizations like NSF International to ensure their effectiveness and safety.

Point-of-Use (POU) filters offer several advantages and disadvantages as a water treatment solution. Understanding these factors can help individuals make informed decisions about whether POU filters are the right choice for their specific needs. Let’s explore the advantages and disadvantages:

Advantages:

1. Convenience: Point-of-Use filters are easy to install and require minimal plumbing modifications. They can be quickly attached to faucets, placed on countertops, or integrated under sinks, making them accessible and user-friendly.

2. Effective Contaminant Removal: POU filters can efficiently remove a wide range of impurities, including chlorine, sediment, heavy metals, volatile organic compounds (VOCs), bacteria, and viruses. Some models, such as Reverse Osmosis (RO) filters, can eliminate even more contaminants, providing high-quality water.

Advantages of Point-of-Use Filters - Water Treatment — Advantages of Point-of-Use Filters – Water Treatment

3. Improved Taste and Odor: By removing chlorine and other chemicals that affect the taste and odor of tap water, POU filters enhance the overall drinking experience, encouraging increased water consumption.

4. Cost-Effective: POU filters offer an economical alternative to purchasing bottled water regularly. Once installed, the filters require periodic replacement of cartridges or membranes, which can be more affordable in the long run compared to the recurring cost of bottled water.

5. Environmental Impact: By using POU filters and reducing reliance on bottled water, individuals contribute to the reduction of plastic waste and its impact on the environment.

6. Customization: With various types of POU filters available, users can select the filter that best suits their specific water quality concerns and preferences.

Checkout these Water Filters here

Disadvantages:

1. Limited Water Volume: Point-of-Use filters are designed for relatively low water flow rates. They are ideal for drinking and cooking water but may not be suitable for high-demand tasks like filling large containers or washing dishes.

2. Filter Replacement and Maintenance: POU filters require regular filter replacement or maintenance to ensure optimal performance. Neglecting this aspect may result in reduced filter effectiveness and compromised water quality.

3. Contaminant Specificity: Different types of POU filters are effective against specific contaminants, but no single filter type can address all water quality issues. The choice of filter should be based on the specific contaminants present in the water.

4. Initial Investment: Some high-end POU filters, such as RO systems, may have a higher initial cost compared to basic carbon or ceramic filters. However, the long-term cost savings on bottled water can offset this initial investment.

5. Space Requirements: Under-sink or countertop POU filters may require some space, which could be a consideration for households with limited available space.

6. Lack of Whole-House Coverage: POU filters provide treatment only at specific points of water consumption, such as the kitchen sink. They do not address water quality concerns throughout the entire home.

Conclusion:

Point-of-Use filters have transformed the way we access clean water at home. By installing these effective water treatment devices, you can take control of your water quality, providing your family with the gift of pure, safe, and delicious drinking water. Embrace the power of Point-of-Use filters and create your oasis of clean water right at your fingertips.

Point-of-Use filters offer numerous advantages in terms of convenience, effectiveness, and cost-effectiveness. However, users should be mindful of their limitations, such as filter replacement and the need to address specific contaminants. For comprehensive water treatment throughout the entire home, users may need to consider whole-house water treatment systems. Ultimately, the choice of water treatment method should be based on the unique water quality needs and preferences of each household.

Water Treatment Point-of-Use Filters

How to Read a Refrigerant Chart

MEP Academy Instructor

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July 18, 2023

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How to read a refrigerant chart. The heat transfer properties of refrigerant is the key ingredient used in the HVAC industry for cooling. Reading a refrigerant pressure-enthalpy (P-H) chart allows you to analyze and understand the thermodynamic properties of a refrigerant at different pressures and temperatures. Being able to read a refrigerant chart allows you check the health of a refrigerant system.

If you prefer to watch the video of this presentation then scroll to the bottom or click on the following link: How to Read a Refrigerant Chart

Here’s a step-by-step guide on how to read a refrigerant P-H chart:

1. Understand the axes: The P-H chart typically has the pressure (P) axis on the y-axis and the enthalpy (H) axis on the x-axis. The pressure is usually measured in units like psi, kPa, or bar, while the enthalpy is measured in units like Btu/lb, kJ/kg, or kcal/kg.

2. Identify the refrigerant: Determine which specific refrigerant is being represented on the chart. Different refrigerants have their own unique Pressure Enthalpy charts, so make sure you have the correct one for your refrigerant of interest.

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3. Locate the pressure: Find the desired pressure on the y-axis of the chart. Trace a horizontal line from that pressure value until it intersects with the graph. If you want to use gauge pressure then add atmospheric pressure.

4. Determine the Temperature: Once the horizontal line intersects the graph, locate the corresponding temperature value on the 100% saturated liquid line or 100% saturated vapor line. The temperature in-between these two saturation lines is constant and runs horizontally, while outside this bubble area the temperature lines run vertically. This temperature represents the saturation temperature of the refrigerant at the given pressure.

The saturation temperature for a refrigerant refers to the temperature at which the refrigerant exists in a state of equilibrium between its liquid and vapor phases at a specific pressure. It represents the temperature at which the refrigerant will undergo a phase change from liquid to vapor (to boil) or from vapor to liquid (to condense).

The Constant Quality line runs vertically within this bubble area indicates the percentage of refrigerant that is in the vapor state. You can see as the constant quality line leaves the saturated liquid line and approaches the saturated vapor line, more and more of the refrigerant is turned into vapor, until it’s 100% vapor at the saturated vapor line.

5. Analyze enthalpy:

Analyze enthalpy: From the intersection point, trace a vertical line downward until it intersects with the enthalpy scale on the x-axis. This gives you the specific enthalpy value for the corresponding pressure and temperature.

The constant temperature and pressure line is where the evaporator turns liquid refrigerant into vapor. When it reaches the saturated vapor line it should be 100% vapor as this is where it will enter the compressors which only works with vapor. The compressor will raise the pressure and temperature up to the condensing temperature and pressure. This small section beyond the saturated vapor line is where de-superheating takes place. This runs from the compressor discharge until it intersects the saturated vapor line, and from there it remains at a constant temperature. See our video on Desuperheating.

Here the condenser line runs from the exit of the compressor until it reaches the expansion valve. In order to reuse the cooling effect of the refrigerant, we’ll need to lower its temperature. This is done by lowering the pressure through the expansion device. As refrigerant pressure is related to temperature. As the refrigerant liquid enters the expansion device some it flashes causing the temperature to lower. You can see that at the entrance to the evaporator a certain percentage of the refrigerant has already been evaporated and turned into vapor, approximately 35% in our example.

6. Interpret properties: Using the enthalpy value, you can gather important information about the refrigerant. For example, you can determine the refrigerant’s state (saturated liquid, saturated vapor, or superheated vapor) and calculate its specific heat capacity or other thermodynamic properties.

7. Additional information: Some P-H charts may include additional data points or curves, such as lines of constant entropy or lines representing superheated vapor or subcooled liquid regions. Familiarize yourself with any such features to extract more information from the chart.

Remember, reading a P-H chart requires understanding of the thermodynamic properties and behavior of refrigerants. It’s recommended to consult relevant textbooks, manuals, or guides to gain a deeper understanding of how to interpret and use these charts effectively.

The bubble point on a refrigerant pressure-enthalpy (P-H) chart refers to the state at which a refrigerant undergoes a phase change from a liquid to a vapor (boiling) when pressure is held constant. It represents the saturation curve or the boundary between the liquid and vapor phases of the refrigerant.

When reading a P-H chart, the bubble point is the point on the chart where the refrigerant is in a saturated liquid state. It occurs at a specific pressure and temperature combination where the refrigerant starts to boil and transition from a liquid phase to a vapor phase.

Superheat

Superheat, in the context of refrigeration systems and a refrigerant pressure-enthalpy (P-H) chart, refers to the temperature increase of a vapor refrigerant above its saturation temperature at a given pressure. It represents the amount of sensible heat added to the refrigerant after it has completed the phase change from liquid to vapor.

On a P-H chart, the superheat region is located beyond the saturation curve, where the refrigerant is in a vapor state and has a temperature higher than its saturation temperature at a specific pressure. The superheat region is typically represented by lines or curves that indicate constant levels of superheat.

Measuring and controlling superheat is crucial in refrigeration systems to ensure optimal performance and prevent potential issues. By monitoring and adjusting the superheat, technicians can achieve efficient and reliable operation of the system.

The superheat value is important for several reasons:

1. System efficiency: Proper superheat ensures that the refrigerant completely evaporates in the evaporator coil before it reaches the compressor. This maximizes the system’s cooling capacity and energy efficiency.

2. Compressor protection: Superheat helps prevent liquid refrigerant from entering the compressor, which can cause damage due to inadequate lubrication and potential compressor failure.

3. Temperature control: Superheat helps maintain a consistent temperature in the evaporator coil, ensuring proper cooling and preventing frost or ice formation.

To determine the superheat value on a P-H chart, locate the point on the chart that corresponds to the operating pressure and temperature of the refrigerant in the superheated vapor state. The difference between this temperature and the saturation temperature at that pressure represents the superheat value.

By monitoring superheat and adjusting system parameters such as refrigerant flow, evaporator pressure, and temperature settings, technicians can optimize the performance and efficiency of refrigeration systems.

Sub-cooling

Subcooling, in the context of refrigeration systems and a refrigerant pressure-enthalpy (P-H) chart, refers to the temperature decrease of a liquid refrigerant below its saturation temperature at a given pressure. It represents the amount of sensible heat removed from the refrigerant after it has completed the phase change from vapor to liquid.

On a P-H chart, the subcooling region is located below the saturation curve, where the refrigerant is in a liquid state and has a temperature lower than its saturation temperature at a specific pressure. The subcooling region is typically represented by lines or curves that indicate constant levels of subcooling.

Sub-cooling is important in refrigeration systems for several reasons:

1. System efficiency: Proper subcooling ensures that the liquid refrigerant is condensed and remains in a liquid state before entering the expansion device. This maximizes the system’s cooling capacity and energy efficiency.

2. Expansion device performance: Subcooling helps optimize the operation of the expansion device (such as a thermostatic expansion valve) by providing a stable liquid refrigerant flow rate and improving the accuracy of the refrigerant metering process.

3. System stability: Subcooling helps maintain a stable refrigerant flow and temperature control, preventing issues such as flashing or unstable operation in the evaporator.

To determine the subcooling value on a P-H chart, locate the point on the chart that corresponds to the operating pressure and temperature of the refrigerant in the subcooled liquid state. The difference between this temperature and the saturation temperature at that pressure represents the subcooling value.

By monitoring subcooling and adjusting system parameters such as condenser pressure, refrigerant flow, and condenser temperature settings, technicians can optimize the performance and efficiency of refrigeration systems while ensuring the proper operation of key components.

Latent Heat of Fusion

The latent heat of fusion for a refrigerant refers to the amount of heat energy that must be added or removed from the refrigerant to cause a phase change from a solid to a liquid state, or vice versa, at a specific temperature and pressure.

When a refrigerant undergoes fusion, which is the transition from a solid to a liquid state, the latent heat of fusion represents the heat energy required to break the molecular bonds and convert the refrigerant from a solid (usually in the form of ice) to a liquid without a change in temperature. Similarly, when a refrigerant solidifies from a liquid to a solid state, the same amount of heat energy is released.

The latent heat of fusion is a characteristic property of each substance, including refrigerants, and is typically expressed in units such as joules per kilogram (J/kg) or calories per gram (cal/g). It is important to note that the latent heat of fusion is specific to the refrigerant being used.

Knowing the latent heat of fusion is significant in refrigeration and air conditioning applications, particularly when dealing with phase change processes such as melting or freezing. Understanding this property helps in sizing components like evaporators and condensers, determining the amount of energy required for phase changes, and predicting the thermal behavior of the refrigerant during these transitions.

It’s worth noting that not all refrigerants exhibit a solid phase at typical operating conditions. Some refrigerants, such as hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs), do not undergo a solid-liquid phase change but instead transition directly between vapor and liquid states. In such cases, the concept of latent heat of fusion may not apply.

Latent Heat of Vaporization

The latent heat of vaporization for a refrigerant refers to the amount of heat energy that must be added or removed from the refrigerant to cause a phase change from a liquid to a vapor state, or vice versa, at a specific temperature and pressure.

When a refrigerant undergoes vaporization, which is the transition from a liquid to a vapor state, the latent heat of vaporization represents the heat energy required to break the intermolecular forces and convert the refrigerant from a liquid to a vapor without a change in temperature. Conversely, when a refrigerant condenses from a vapor to a liquid state, the same amount of heat energy is released.

The latent heat of vaporization is a characteristic property of each substance, including refrigerants, and is typically expressed in units such as joules per kilogram (J/kg) or calories per gram (cal/g). It is important to note that the latent heat of vaporization is specific to the refrigerant being used.

Knowing the latent heat of vaporization is crucial in refrigeration and air conditioning applications as it helps in sizing components such as evaporators and condensers, determining the amount of energy required for phase changes, and predicting the thermal behavior of the refrigerant during these transitions.

The latent heat of vaporization also plays a significant role in the overall cooling process. When the refrigerant evaporates, it absorbs heat energy from the surroundings, providing the cooling effect. Later, when the refrigerant condenses, it releases the absorbed heat energy, which is transferred to the environment or rejected through the condenser.

Understanding and utilizing the latent heat of vaporization is essential for designing and operating efficient refrigeration systems. It allows engineers and technicians to optimize system performance, select appropriate equipment, and determine the energy requirements for the desired cooling or refrigeration applications.

Sensible Heat

The sensible heat of a refrigerant refers to the amount of heat energy that causes a change in the temperature of the refrigerant without a change in phase (from liquid to vapor or vice versa). It is the heat energy associated with changing the sensible (perceptible) temperature of the refrigerant.

When heat is added or removed from a refrigerant in its liquid or vapor state, the sensible heat causes a change in temperature without causing a phase change. Sensible heat can be measured and quantified as the product of the mass of the refrigerant and its specific heat capacity.

The specific heat capacity is the amount of heat energy required to raise the temperature of a unit mass of the refrigerant by one degree Celsius or Kelvin. It is a characteristic property of the refrigerant and varies depending on the specific substance.

The sensible heat of a refrigerant is relevant in refrigeration and air conditioning systems for various reasons:

1. Temperature control: Adding or removing sensible heat allows for precise control of the refrigerant’s temperature, ensuring that it meets the desired cooling or heating requirements.

2. Comfort control: In air conditioning applications, adjusting the sensible heat of the refrigerant helps regulate the temperature of the conditioned space to provide comfort for occupants.

3. Heat transfer: Sensible heat transfer occurs in heat exchangers, such as evaporators and condensers, where heat is exchanged between the refrigerant and the surrounding medium (air or water) without a phase change.

In refrigeration and air conditioning systems, sensible heat is typically managed through processes such as heat exchange, throttling, and temperature control devices to achieve efficient and controlled cooling or heating.

Understanding the concept of sensible heat is important for system design, operation, and troubleshooting, as it enables engineers and technicians to optimize cooling or heating processes, select appropriate equipment, and ensure efficient heat transfer within the system.

Latent Heat

The latent heat of a refrigerant refers to the amount of heat energy that is absorbed or released during a phase change of the refrigerant, such as the transition from a liquid to a vapor state (vaporization) or from a vapor to a liquid state (condensation), at a constant temperature and pressure.

When a refrigerant undergoes a phase change, the latent heat represents the heat energy required to break or form intermolecular forces without causing a change in temperature. It is called “latent” because this heat energy is hidden or concealed within the refrigerant during the phase change.

The latent heat of a refrigerant can be divided into two components:

1. Latent heat of vaporization: This is the amount of heat energy absorbed or released when the refrigerant changes from a liquid to a vapor state (vaporization). The latent heat of vaporization is typically associated with the evaporator in a refrigeration or air conditioning system, where heat is absorbed from the surroundings to convert the refrigerant into a vapor.

2. Latent heat of condensation: This is the amount of heat energy released or absorbed when the refrigerant changes from a vapor to a liquid state (condensation). The latent heat of condensation is typically associated with the condenser in a refrigeration or air conditioning system, where heat is released to the surroundings as the refrigerant condenses.

The latent heat of a refrigerant is an important factor in the cooling or heating process. It determines the amount of heat energy required or released during phase changes and influences the overall heat transfer and efficiency of the system.

Understanding the latent heat of a refrigerant is crucial for designing and operating efficient refrigeration and air conditioning systems. It allows engineers and technicians to determine the energy requirements, select appropriate equipment, and optimize the heat transfer processes to achieve desired cooling or heating effects.

Bubble Point

The bubble point is important in refrigeration systems because it helps determine the conditions at which refrigerant evaporates inside the evaporator coil. By knowing the bubble point, you can determine the saturation temperature and pressure at which the refrigerant will change from a liquid to a vapor, which is crucial for system design, operation, and troubleshooting.

On a P-H chart, the bubble point is typically represented by a curved line or boundary that separates the liquid region from the vapor region. This curve shows the relationship between pressure and enthalpy for the refrigerant during the boiling process at constant pressure.

Understanding the bubble point and its location on the P-H chart allows engineers, technicians, and professionals in the refrigeration industry to analyze the behavior of the refrigerant and make informed decisions regarding system performance, capacity, and efficiency.

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Desuperheater

HVAC Systems

MEP Academy Instructor

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July 11, 2023

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Desuperheater. In this article we’ll show you how a desuperheater can be used in conjunction with a service water heater to increase its energy efficiency. It works by utilizing waste heat from an air conditioning or refrigeration system to preheat the water before it enters the service water heater.

If you prefer to watch the video of these presentation than scroll to the bottom or click on the following link. Desuperheater.

Desuperheater connected to a Refrigerant Circuit

Here’s a general overview of how a desuperheater could works, our system is slightly different as were using a service water heater in a grocery store that has the need for hot water such as in a kitchen, but the concept is the same:

1. System Setup: The desuperheater is typically integrated into a heat pump or air conditioning system, and consists of a heat exchanger.

2. Heat Extraction: When the air conditioning or refrigeration system operates, it produces high-pressure, high-temperature refrigerant vapor. The desuperheater diverts this superheated refrigerant to the heat exchanger.

3. Heat Transfer: The superheated refrigerant passes through the heat exchanger, where it transfers its heat to the water flowing through the heat exchanger. This heat transfer process raises the temperature of the water.

4. Temperature Control: The control valve regulates the flow of superheated refrigerant to the recovery tank heat exchanger, adjusting the amount of heat transferred based on the desired water temperature. This ensures that the water doesn’t get excessively heated.

5. Preheated Water Supply: The preheated water from the desuperheater is then directed to the service water heater. The service water heater’s primary heating source, such as a gas burner or electric element, will still be needed to raise the temperature further to the desired hot water temperature.

By utilizing the waste heat from the air conditioning or refrigeration system, the desuperheater reduces the workload on the service water heater’s primary heating source. This can result in significant energy savings and increased overall system efficiency, as the water heater doesn’t have to work as hard to reach the desired temperature.

It’s worth noting that the effectiveness of a desuperheater depends on factors such as the operating conditions of the air conditioning or refrigeration system, the demand for hot water, and the temperature difference between the preheated water and the desired hot water temperature. Consulting with a professional HVAC technician or engineer is recommended for a proper assessment and installation of a desuperheater system.

Refrigerant Chart

Looking at a refrigerant chart of this process we can see that after the compressor raises the pressure and temperature of the refrigerant, it then enters the desuperheater where it gives up its heat.

Desuperheater in a Geothermal Heat Pump System

A desuperheater can be used in conjunction with a geothermal heat pump to provide additional hot water heating capabilities. In a geothermal heat pump system, the desuperheater utilizes excess heat generated during the cooling cycle to heat water for domestic use.

Here’s a general overview of how a desuperheater works with a geothermal heat pump:

1. System Setup: The desuperheater is integrated into the geothermal heat pump system. It consists of a heat exchanger, a control valve, and a separate storage tank for hot water.

2. Heat Extraction: During the cooling mode of the geothermal heat pump, excess heat is generated and normally dissipated into the ground. Instead, the desuperheater diverts this excess heat from the heat pump’s refrigerant to the heat exchanger.

3. Heat Transfer: The superheated refrigerant flows through the heat exchanger, transferring its heat to the water flowing through a separate set of pipes within the exchanger. This process heats up the water as it passes through.

4. Temperature Control: The control valve regulates the flow of superheated refrigerant to the heat exchanger, adjusting the amount of heat transferred based on the desired water temperature. This ensures that the water doesn’t get excessively heated.

5. Hot Water Storage: The preheated water is directed to a separate storage tank dedicated to hot water. The geothermal heat pump’s circulation system then draws from this tank whenever hot water is needed in the building.

By using the excess heat from the geothermal heat pump’s cooling cycle, the desuperheater provides a supplemental source of hot water. This can significantly reduce the energy consumption associated with heating water separately.

It’s important to note that the effectiveness of a desuperheater in a geothermal heat pump system depends on factors such as the operating conditions, the cooling load, and the hot water demand. Consulting with a professional HVAC technician experienced in geothermal systems is recommended to properly assess and install a desuperheater for a geothermal heat pump.

Desuperheater for Heat Recovery

High-Capacity Airflow Diffusers

Various Styles of Air Distribution

Designing Air Distribution for Large Area’s

Key Considerations for Designing Large Open Area’s

Why large capacity air diffusers work effectively:

Computational Fluid Dynamics

What Are Point-of-Use Filters?

How Do Point-of-Use Filters Work?

Applications of Point-of-Use Filters:

Choosing the Right Point-of-Use Filter:

Advantages:

Disadvantages:

Conclusion:

Superheat

The superheat value is important for several reasons:

Sub-cooling

Latent Heat of Fusion

Latent Heat of Vaporization

Sensible Heat

Latent Heat

Bubble Point

Refrigerant Pressure Temperature Charts

Refrigerant Chart

Desuperheater in a Geothermal Heat Pump System

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