In order to maintain the health and well-being of the workers, it is critical that industrial ventilation and exhaust fume extraction systems are properly designed, constructed, and operated, and are in full compliance with the applicable requirements. One of the tools that can make this task easier is computational fluid dynamics, or CFD, which allows HVAC engineers to virtually test the performance of their industrial ventilation designs.

To illustrate how fluid flow simulation can help optimize HVAC system designs for exhaust fume extraction, SimScale hosted a short webinar. Watch the recording below:

Watch Free Webinar

Case Study: Fume Extraction System Design

For the purpose of this case study, one of our customers agreed to share their successfully completed project. We have a large working space, with enclosed coating stations that produce toxic fumes and a small amount of fumes produced by the freshly coated parts. Our goal is to find the optimal inlet and outlet locations, as well as the total inlet and outlet mass flow.

Design 1: Fresh Air Supply from Top Inlets

In a few easy steps, we upload the CAD model to the platform, set up the simulation and analyze the results. First of all, let’s take a look at the airflow velocity. We can see that in the first design configuration, the flow is oriented to keep fumes away from the working area. However, there are several problems, including the reversed flow behind coating area, as well as strong drafts which would create an uncomfortable environment for the workers.

When we look at the results from a different angle, we can see the presence of flow recirculation between the coating stations, which reduces the exhaust fume extraction efficiency. A strong draft from the inlet fails to move the flow away from the coating stations.

If we visualize the airflow using streamlines, we can see that the flow from the coating stations travels a long way before being extracted, mixing with the surrounding air, and the airflow patterns around the coating stations are erratic.

Now let’s look at the toxic exhaust fume distribution. The fumes were modeled as a passive scalar quantity. The ideal maximum concentration is c<0.25, while the safety limit with minimum respiratory gear is c<0.5.

We can immediately see a large red region with the concentration above the 0.5 limit (154m2). With the current ventilation system configuration, in a large section of the factory floor, the toxic fume concentration rises above the acceptable limit, even with security gear.

Now that we have identified the weak points of our original design (flow recirculation areas and fume concentration above the safety level), we need to find possible design modifications that would address those issues. One would be to increase the flow rate, which would increase the draft. However, this change would come with several adverse side effects. The energy consumption would increase, while the thermal comfort of the workers would deteriorate. We could also try to move the outlets and fume extractors closer to the coating stations. In this case study, we will investigate the impact of the latter solution.

Design 2: Layout Changes

When we run the simulation for the new modified design, we can immediately observe strong drafts around the coating stations, which ensure the fumes get extracted. Local fume extractors diminish the impact of the reversed flow around the coating line.

The local fume extraction outlets receive the flow from the coating station’s openings. We have also eliminated the recirculation below the inlet.

The flow from the coating stations gets extracted immediately and the flow patterns around the coating line are very straightforward.

If we look at the simulation results showing the toxic fume distribution, we can see that the region with the fume concentration above the safety limit has been virtually eliminated (reduced to 4m2). No significant fume concentration can be found throughout the working area. With the design changed, the toxic fumes were successfully contained around the coating stations. This design also eliminates the need for the workers to constantly wear the respiratory safety gear.

The whole simulation took less than two hours of manual time, five hours of computing time, and 150 core hours. Within that time, we were able to identify the possible design flaws in the original ventilation configuration and validate alternative industrial ventilation strategies to find the best solution. Since SimScale is a cloud-based platform, all we needed was a laptop with an Internet connection, and all the simulations were run directly in the web browser.

To learn more about this case study and see the SimScale platform in action, watch the recording of the webinar for free:

Watch Free Webinar

Read more articles like this by checking out our SimScale Blog here!

The post Industrial Ventilation: Testing Exhaust Fume Extraction System Designs appeared first on SimScale.

Thermal comfort is a key component of the indoor environment and, in most cases, it is also a legal requirement. The heating and air conditioning system can be said to have performed its task if occupants are not ‘conscious’ of the temperature inside the building. In this article, we will investigate how thermal comfort can be predicted and optimized with the help of computational fluid dynamics (CFD) simulation.

Sign up and check out our SimScale blog for much more!

Read More Now

Ensuring Thermal Comfort with HVAC for a School Building Design: Case Study Ramboll

HVAC system designers and mechanical engineers face thermal comfort problems on a regular basis. The main reason for poor air quality and low thermal comfort is often inadequate heating and air conditioning. Let’s take a real-life example and get a closer look at an engineering project that Ramboll UK, a leading engineering and construction company, executed together with SimScale. Watch the recording of a webinar where we discussed it in detail by submitting this short form.

The project was centered around the design of a school building in Scotland after the Department of Education issued new, more restrictive thermal comfort standards.

The goal of this project was to simulate the performance of the mixing box system case in a winter scenario, with the windows closed and the fans turned on. The model of the classroom was designed using Rhino and then imported into the SimScale platform.

A mesh containing around 18.96 million 3D cells was then generated on the SimScale platform. The detailed summary of the simulation setup can be seen in the table below.

After running a CFD simulation, we have obtained qualitative and quantitative results showing velocity, temperature distribution, and thermal comfort, which we can use to adjust the heating and air conditioning system design or to rearrange desks and chairs in the classroom.

Looking at the velocity distribution, we can identify three regions of the flow—the inlet flow velocity, the flow velocity through the grills, and the buoyancy draft velocity. We can also observe a high-velocity turbulent flow in the area of the inlet. Natural convection can be seen near the cold windows.

When we rotate the model and look at the velocity distribution at the shoulder level and above the head level of the students, we can see that none of the occupants are strongly affected by the draft from the inlets.

To accurately evaluate thermal comfort in the classroom, we would need to investigate temperature in addition to velocity. We can see that the temperature is much higher above the head level of the occupants, in the area of the inlets and outlets. However, at the shoulder level, an evenly comfortable temperature is maintained.

To estimate the thermal comfort, we will use effective draft temperature (EDT), a quantifiable indication of comfort at a discrete point in a space generated by combining the physiological effects of air temperature and air motion. A point is considered comfortable if the results are between –3° and +2°, and if the measured velocity at the point is less than 70 fpm (0.36 m/s).

CFD allows us to easily estimate and visualize EDT for every point in the room. We can immediately see several highly uncomfortable areas below the inlets, so we should avoid placing any occupants there. Overall, the classroom is currently designed to be thermally comfortable for the majority of students. However, the position of several tables and chairs may need to be adjusted.

Conclusion

The CFD simulation above was performed by Ramboll in a web browser using the cloud-based SimScale platform, using 22 hours of computational time (704 core hours). Performing the same simulation offline on a local computer would have taken up to one month.

This project from Ramboll was just one brief example of how a cloud-based CFD simulation tool can help engineers predict and optimize the performance of a heating and air conditioning system in the early stages of the building design process. This is a particularly relevant topic for the planning of green building projects and obtaining LEED certification, where sustainability, energy performance, and thermal comfort play a crucial role.

For a more detailed analysis of the results, as well as a commentary on the project by Ian van Duivenbode, a senior building physics engineer at Ramboll UK, watch the recording of the webinar below:

Watch the Recording

The post Ensuring Thermal Comfort with HVAC for a School Building Design: Case Study Ramboll appeared first on SimScale.

Download ‘Electronics Cooling: The Ultimate Guide’ to learn everything you need to know about modern electronics cooling.

Download Now

With the aid of engineering simulation or CAE, electronics designers and engineers can:

Validate Material Decisions

The thermo-physical properties of the materials you choose can largely determine the thermal performance of the final design, making the material selection one of the primary design decisions. The thermal conductivity of materials such as copper or silicon can change over the expected range of operating temperatures. Thermal simulation software allows you to validate your material decisions and test their conductivity for a faster cooling process, keeping semiconductors cool enough to prevent failure.

Find the Right Placement for Fans and Heat Sinks

Fans and heat sinks are widely used in electronics for active and passive colling management, in order to keep the temperature within specified limits. It is important to optimize the flow path and ensure that the heat sinks are placed in such a way that they don’t impede it. Visualizing the airflow and temperature distribution around different components inside the electronics enclosure enables you to identify the best possible placement of fans and heat sinks for a more efficient cooling process.

Test Enclosure Dimensions

The physical size of the enclosure is the primary factor in determining its ability to dissipate heat, making it a fundamental factor in thermal design. Engineering simulation tools allow you to analyze the heat flow and decide on the best dimensions of an electronics enclosure and ensure the effectiveness of the cooling strategy for semiconductors.

 Compare Active & Passive Cooling

Modern thermal technologies present designers with a wide variety of strategies for electronics cooling. Should you use heat sinks or fans—or a combination of both? Would passive cooling be enough to prevent thermal damage to your product? Should you invest in an active thermal management solution despite its costs and noise concerns? Evaluate your options and choose the most appropriate cooling strategy for your product based on the simulation results.

  Ensure Energy Efficiency

The increasing energy costs and the need for reducing energy consumption are driving the demand for not only effective but also energy-efficient cooling solutions. Thermal simulation helps you virtually test different types, dimensions, and placements of heat sinks and fans to improve energy efficiency for cooling and eliminate excessive components.

If you want to learn about all of our thermal modeling software solutions, check out our thermal analysis hub.

To learn how you, as a designer or engineer, can benefit from virtual prototyping in thermal design, download this free infographic!

Download Free Infographic

The post Thermal Design for Electronics with Cloud-Based Engineering Simulation appeared first on SimScale.

What is Computer-Aided Engineering (CAE)?

Computer-aided engineering (CAE) is a term used to describe the use of computer software in the product engineering process, from design and virtual testing with sophisticated analytical algorithms to the planning of manufacturing. CAE solutions support the engineering process, allowing designers to perform tests and simulations of the product’s physical properties without needing a physical prototype. CAE or engineering simulation has become the go-to tool for engineers in many industries, replacing older design and validation practices.

Computer-Aided Engineering (CAE) in

Sounds intimidating? Let’s consider the alternatives.

Traditional Product Design Practices

Excel spreadsheets. Due to the predominance of the Microsoft Office environment, many designers still cling to Excel spreadsheets for engineering calculations. And while it might work well for the finance department, it often results in expensive errors in product development.

According to Ray Panko, a professor of IT management at the University of Hawaii, “spreadsheets, even after careful development, contain errors in 1% or more of all formula cells. In large spreadsheets with thousands of formulas, there will be dozens of undetected errors” [1].

Over the course of his research, he also found that:

• 30% of spreadsheets contain errors
• 90% of sheets with 150+ rows have errors
• 50% of spreadsheet models have material defects

Even for the simpler calculations, which Excel is capable of performing, several issues make it an unsuitable engineering tool—the biggest being the fact that it’s unreviewable. The more detailed and complex the spreadsheet is, the easier it is to get blinded by details and miss errors. It is a common tool that too frequently ends up being used in problems it is not suited for. And while the fact that it’s easily available and affordable makes it a tempting choice, the calculation errors and resulting design flaws tend to be far more costly than more reliable alternative engineering tools.

Physical prototypes. Producing multiple physical prototypes and testing them is one of the oldest product development practices. And while it has its benefits, there are many cases where rapid prototyping is impractical, impossible or inefficient.

For instance, for early concept models where changes are fast and frequent, simulation and virtual prototyping would be far more useful and cost-efficient. The same would be true for later product development stages, which involve reviewing and refining the designs of objects like planes and buildings. In those cases, creating physical prototypes of all necessary design components would be pushing the limits of both cost and time. Physical prototypes are also quite restrictive when it comes to analyzing complex physical phenomena, such as fluid flow.

It is important to note that physical and virtual prototyping are not two competing technologies; they are complementary. It is not recommended to try and entirely eliminate physical prototyping from the design process, but instead, integrate virtual prototyping and simulation at appropriate development stages to address its weaknesses and limitations.

Advantages of Virtual Prototyping and CAE

Engineering simulation has been steadily replacing traditional testing techniques across many industries. The shift makes sense when we consider the advantages offered by virtual prototyping:

Shorter time to market. The traditional product development process typically involves building a physical prototype and taking it to the lab for testing. The testing will likely reveal several design flaws that require a re-design or re-configuration. This build–test–redesign–retest cycle can stretch the development schedule indefinitely. Virtual prototyping, on the other hand, eliminates the unnecessary loops from the design optimization process, by allowing virtual testing and design adjustments, cutting both time and costs of development as a result.

Higher design quality. Performing engineering calculations using a spreadsheet and then building and testing a prototype can miss some fundamental errors. These errors might result in design flaws that will not become apparent before the product gets manufactured and distributed, resulting in warranty costs and even recalls. And while CAE does not automatically guarantee a flawless design, using fluid flow or structural simulation tools allows engineers to test their products under a much larger variety of conditions and considerably improve their reliability and durability.

More competitive product. Overly relying on physical experimentation limits the number of creative ideas the designer can test.  Virtual prototyping, on the other hand, is far less costly and time-consuming and allows engineers to freely experiment with innovative designs and scenarios, developing a highly competitive product in terms of functionality, performance and exterior design.

Success Stories

Since the launch of the SimScale cloud-based CAE platform, we have collected numerous user success stories of companies who leveraged our virtual prototyping and simulation functionalities to build their products better, faster and more cost-efficiently.

Johnson Screens, Aqseptence Group. Johnson Screens used SimScale CFD to verify the airflow through their architectural radiator grille that would be used in a high-profile skyscraper in New York. By running a virtual test which took only 18 minutes, the team was able to find an accurate measure of the pressure drop and provide professional flow contour visualizations to their customer. The company estimated that in order to conduct the same analysis with a physical experiment, it would need approximately $7,000-$15,000 and a few months of time.

L&T Construction. L&T Construction, part of the Larsen & Toubro multinational company, used virtual prototyping to optimize the structures in the sump cum pump house to ensure that the flow reaching the pumps is free from any vortices. With SimScale, the L&T team reduced the time to solve the problems in the sump geometry by approximately 15 days. Moreover, almost $38,000 in costs were saved.

…And many more! Read more success stories with SimScale on this page.

CAE Starter Kit

Ready to add your success story to the ones above? Here’s everything you need to get started.

Software. Don’t be intimidated by the 5-digit prices charged by many traditional CAE software providers. SimScale grants you access to the full scope of the simulation capabilities of its platform. Simply create a free Community Account. If you’d like to learn more about the SimScale cloud-based platform and its capabilities, download this features overview.

Hardware. Don’t have access to a supercomputer? With the emergence of cloud-based CAD and CAE tools, this is no longer a barrier—platforms like Onshape and SimScale grant you access to their full design and simulation functionalities directly from a web browser. SimScale is being constantly maintained and upgraded, so all users share the same experience without any additional maintenance costs. Your CAD and simulation data is protected by one of the world’s strictest data protection and privacy standards to give you peace of mind.

Expertise. Traditional on-premises software is made for experts in numerical analysis, rather than product designers and engineers. While running complex simulations and getting accurate reliable results is by no means easy, the expertise gap can be minimized with:

• Intuitive UI
• Large simulation template library
• Live support via chat or forum
• Free training materials

Any of the public projects in the SimScale Library can be imported into your workspace, so you can simply exchange the CAD model, reassign the boundary conditions and run it without having to know too much about simulation upfront.

Introduction to CAE — Enroll for Free

Conclusion

Having the right tools alone is not enough to extract real value from them. For firms that have no experience using simulation in their product development process, integrating CAE into their workflow can be a challenge. The company has to fully commit to a new methodology.

In order to truly shorten your design cycle times and get a better product to market faster, it is important to make virtual prototyping and simulation tools an integral component of your product development process. Using CAE tools from design conception to manufacturing delivery and not an afterthought will enable you to reap all their benefits.

It is important to understand here that committing to this change would mean it might take longer before you have the first piece of hardware in your hands. Your main goal, however, is to cut the total design process time and lower the costs, while ensuring the best possible quality of your final product—and engineering simulation can make that possible.

The post How Virtual Prototyping Can Benefit Your Product Design Process appeared first on SimScale.

Rising awareness of the costs and environmental impacts of high energy consumption has made passive ventilation, also referred to as natural ventilation, an increasingly attractive method, especially in green building design. It is capable of maintaining high indoor air quality and a healthy, comfortable indoor climate while bringing a much higher level of energy efficiency. In certain climates and building types, natural ventilation can be a highly preferable alternative to mechanical air-conditioning systems, saving 10%–30% of total energy consumption. [1]

What is Passive Ventilation

Very broadly, ventilation systems can be categorized as natural or mechanical. Mechanical ventilation (or forced ventilation) systems move fresh air through buildings using fans, blowers, or other mechanical components, while passive ventilation (or natural ventilation) relies on pressure differences, taking advantage of physical properties of air.

These pressure differences can be caused by wind or the buoyancy effect created by differences in temperature or humidity. In either case, the amount of ventilation will critically depend on the size and placement of openings in the building. A passive ventilation system can be compared to a circuit: openings between rooms (such as transom windows, louvers, grills, or open plans) complete the airflow circuit through a building.

Passive Ventilation Advantages

Passive ventilation is a must for a green building. If the climate and building type allow it, there are a lot of good reasons why you should choose passive ventilation. Here are some of the advantages of a passive ventilation system:

• Reduced (or eliminated) costs of building, operating and maintaining the system
• Lower energy consumption for the building
• Lack of fans means lower noise, increasing the comfort of the occupants
• More design freedom and better use of space inside the building

However, the implementation of such a system does not come without disadvantages and challenges:

• Local air quality may be poor, for example, if the building is next to a busy road
• High noise levels may make it difficult to open windows
• If the local urban area is very dense, it may shelter the building from the wind
• Security concerns may prevent the windows from being opened
• Openings may create draughts inside the building
• The occupants have less control over the internal environment
• Code requirements regarding smoke and fire transfer may present challenges

How CFD Simulation Can Help You Test the Performance of Passive Ventilation

Despite the potential challenges, the tremendous benefits of passive ventilation often make it the first option investigated during the building design process. Using passive ventilation may be a tempting option, but it is difficult to solely rely on this solution without proof of performance. This is where computational fluid dynamics simulation can help, enabling you to validate the use of natural convection in a building and reduce the costs of artificial air exchange systems.

To see for yourself how a cloud-based CFD simulation software can help in making informed decisions about using passive ventilation as a part of a commercial building’s air exchange system, watch this free webinar:

Watch Free Webinar Recording

Case Study: Shopping Mall Ventilation

For this case study, we will use CFD simulation with SimScale to test the effectiveness of natural ventilation in a shopping mall depending on the windows configuration. This simulation project called “Passive Ventilation Design for a Department Store” was used for the analysis and can be freely copied and used as a template. In this project, we will consider the ventilation of a 3-story shopping mall building, with the rectangular boxes representing people, for simplification purposes.

The performance of a passive ventilation system in a commercial building depends on the following factors with corresponding standards:

1. Airspeed inside the building
   • ASHRAE 55: interior airspeed should not exceed 0.2 m/s, extended to 0.8 m/s [2]
2. Air exchanges per hour
   • ASHRAE 62.1: 6-10 exchanges for shopping centers [3]

Simulation Setup

To accurately predict the effectiveness of natural ventilation in this commercial building, let’s consider five scenarios with different window configurations: with all windows open, with ground, 1st or 2nd-floor window open, and with all windows closed. We will assume a situation in which a 5 m/s breeze is blowing directly at the entrance. For this analysis, let’s use a steady state, laminar flow simulation type, with air as the selected fluid. The following boundary conditions are applied:

Inlet: fixed velocity, 5 m/s
Outlet: pressure outlet
External sides: walls, slip
Building and internal elements: walls, slip

The simulation of the building design took approximately 5 hours of computing time.

Simulation Results

The simulation results prove that not enough air will be provided in order to ventilate the entire commercial building, making passive ventilation an unsuitable design choice. We can derive the following conclusions about the performance of the ventilation system:

1. Wind ventilation can significantly affect the airflow within a building.
2. The ventilation using windows on one side of the building does not provide sufficient air exchange.
3. Wind ventilation can be used to induce air circulation within the building but it might cause excessively fast air motion.
4. Keeping the door open during a breeze will cause discomfort for the visitors at the bottom floor, the installation of wind obstacles is worth investigating.

These insights allow us to make changes to the overall building design, as well as the windows placement to maximize the efficiency of natural ventilation and avoid causing discomfort for the occupants or visitors. For a more detailed analysis of the results as well as a live demonstration of how CFD simulations can help you test the effectiveness of passive ventilation, watch this free webinar:

Watch Free Webinar Recording

So why aren’t all engineers using fluid flow simulation in building design yet?

• • Accessibility: Traditional CAE software needs to be installed locally on expensive high-performing computers, the majority of which remain idle most of the time. With SimScale, all computations are cloud-based—all that is needed is a web browser.

  • Operating costs: Standard commercial simulation software packages are notoriously expensive. With SimScale, there is an option to start simulating right away with a free Community Plan.

  • Know-how: Most modern tools are designed for experts and experienced simulation engineers. To bridge that knowledge gap, SimScale offers a large public projects library, free training, and live support via chat.

If you’d like to read more about how CFD simulation helps engineers and architects improve building performance, download this free white paper.

The post Validating Passive Ventilation in Building Design with Fluid Flow Simulation appeared first on SimScale.

Nonetheless, fluid flow simulation holds great promise for the AEC industry, giving architects and engineers the ability to predict and optimize the performance of buildings in the early stages of the design process. And with the recent efforts to democratize CFD software technology, including the emergence of easy-to-use, cloud-based platforms with flexible pricing systems, tapping into its full potential is no longer an impossible task.

With the aid of CFD modeling, engineers in the AEC industry can:

  Validate HVAC Systems and Parts

CFD software can help HVAC engineers examine the effectiveness and efficiency of various heating and ventilation systems by virtually testing different diffuser types and locations, as well as supplying air conditions and system control schedules. It can also be successfully used to predict the performance of fans, compressors or pumps, investigate flow, minimize pressure drop in ducts, or optimize heating and cooling equipment.

Predict Wind Loads

Wind forces are an important design parameter for tall buildings, billboards, solar panels, offshore platforms, and other structures, especially at the preliminary design stages. CFD presents a realistic and cost-efficient alternative to experimental testing, allowing architects and civil engineers to test their designs and estimate the bending and the twisting phenomenon on structures without using tabular values from standards and codes.

If you are interested in knowing more about wind comfort prediction, watch this webinar recording:

Download our ‘ Tips for Architecture, Engineering & Construction (AEC)’ white paper to learn how to optimize your designs!

Download Now

Optimize Thermal Comfort

Thermal comfort is an important consideration in the design and layout of residential and commercial buildings. Achieving a healthy and comfortable indoor climate for the occupants depends on several factors, including air velocity, temperature, and humidity. All of these can be accurately predicted and analyzed with the help of fluid flow simulation, allowing engineers to visualize the airflow and heat transfer, test different air supply outlets and inlets, and evaluate temperature gradients, air distribution or velocity plots.

Control Air Quality and Contamination

An accurate analysis of airflow in ventilated spaces is critical for achieving healthy conditions in indoor environments. CFD modeling has emerged as a highly promising technology for such assessments, effectively replacing the wind tunnel testing methods that were used in the early days of construction. This innovative approach allows designers to create a smart ventilation strategy, ensuring the efficient removal of high contaminant concentrations in cleanrooms, labs or factories, predicting smoke propagation in underground garages, subway stations or shopping centers, and more.

  Improve Energy Efficiency

HVAC systems in numerous facilities—data centers and server rooms in particular—consume far more energy than required, offering considerable potential for optimization. CFD software simulation is a versatile tool for predicting the thermal performance of HVAC systems by analyzing the airflow and heat transfer characteristics, which helps engineers accurately identify hidden energy-saving and cost-cutting opportunities. With the ever-rising demands for sustainable HVAC solutions and green buildings, it has become an invaluable design validation technique.

To learn how you, as a designer, engineer, or architect can benefit from virtual prototyping, download this free infographic!

Download Free Infographic

If you enjoyed this blog, check out more interesting articles here! 

The post CFD Simulation for Architecture, Engineering and Construction (AEC) appeared first on SimScale.

Data Center Infrastructure Management (DCIM) with CFD

The energy required to store and maintain large amounts of data can be used with greater efficiency if the infrastructure of that data is appropriately managed. One of the most important aspects here would be proper temperature management, which is absolutely vital to keep the equipment running and maintain its functionality. Cooling systems tend to be highly energy-intensive, and often use as much (or even more) energy as the servers they support. On the other hand, a well-designed cooling system may use only a small fraction of that energy.

Moving with the need of the times, nowadays, various software tools have been developed to tackle the specific needs of a data center, referred to as data center infrastructure management (DCIM). One such tool is computational fluid dynamics (CFD). Fluid flow simulation allows HVAC design engineers to visualize airflow patterns and predict the flow distribution, and use this information to optimize the supply air temperature and the supply air flow rate, reducing the overall cooling costs.

To see how CFD simulation can be applied to reduce the cooling costs of an existing data center, watch the recording of this free webinar:

Watch Webinar Recording

Measuring Data Center Thermal Performance

Facilities should be designed and operated to target the recommended range. According to ASHRAE, the recommended equipment intake temperature range is 20-25°C, while the allowable range is 15-32°C.

In order to measure how well the inlet temperatures comply with a selected inlet temperature standard, a measure called the rack cooling index (RCI) is used. RCI consists of two metrics: high end (HI) and low end (LO). RCI-HI is used to measure the equipment’s health at the high end of the temperature range. The RCI-LO is a complement to RCI-HI when the supply condition is below the minimum recommended temperature.

Project Overview and Simulation Setup

As an example, let’s use one of the projects from the SimScale Simulation Projects Library.

The aim of the project is to optimize the rack cooling effectiveness and reduce the cooling cost of a typical data center, housing four CRAC units. The modeled facility consists of 4 rows of 13 server racks each, for a total of 52 server racks. Each of them dissipates 4 KW of heat. As a result, the total space load is 208 KW. The total rack airflow is 56680 m^3/hr.

The key design parameters that we will evaluate are:

1. Supply temperature
2. Supply airflow rate
3. Rack cooling effectiveness (RCI)
4. Cooling cost function

With that in mind, we will analyze 16 different combinations of supply temperature and supply airflow rate, and their impact on the cooling effectiveness and cooling cost. The supply temperature that we will consider will vary between 13 – 21°C, and the supply airflow rate will range from 80% to 140% of the total rack airflow rate. The results will help us identify the best combination of the two parameters to optimize the overall cooling system configuration. This will allow a reduction in the data center power consumption.

Results: Reduced Data Center Power Consumption by 11%

Let’s have a closer look at one of the 16 simulations that we ran at 120% of flow rate capacity with a 16°C supply air temperature. The image below shows the server intake temperatures taken as a slice—we can immediately see the differences between the rows.

The velocity plots below provide us with additional insights into the behavior of the cooling system through the velocity plots with streamlines.

With the obtained results, we can calculate the relevant values for every one of the 16 configurations and determine the best performing one. Using the formulas we introduced earlier, we can calculate the RCI-HI and RCI-LO coefficients, which reflect the operational conditions for the system. Based on numerous studies, a value at or above 95% is a sign of a good design. With that in mind, we can see that when it comes to RCI-HI, all operational conditions produce satisfactory results with the exception of the low-volume air supply (21°C/80% and 21°C/100%). When we look at the RCI-LO coefficients, only the configuration with 21°C would satisfy our requirements. When we combine the two coefficients, we are left with two possible configurations: 21°C/120% and 21°C/140%.

As a final step, let’s calculate how much energy we can save by choosing one of the two cooling system designs. Using the cost of $33,150 for 13°C/100% as an arbitrary reference, we can conclude that switching to the 21°C/120% would allow us to save 11% of the cooling costs.

Eager to Get Started with Your Own Simulation?

Making the right design decision for your facility depends on a variety of factors, such as power density, room size, budget and so on. Fluid flow simulation allows you to find the unique cooling system configuration that would fit your facility best and help you reduce your data center power consumption. To set up your own CFD simulation, simply create a free account on the SimScale cloud-based platform and upload your CAD model. If you’d like to learn more about the SimScale cloud-based platform and its capabilities, download this features overview.

For more details on the simulation presented in this article, watch the recording of this webinar:

Watch Webinar Recording

If you want to read more about how CFD simulation helps engineers and architects improve building performance, download this free white paper.

The post How to Reduce Data Center Power Consumption With CFD appeared first on SimScale.

Why is CFD Important?

Design problems involving fluid forces such as water and air are some of the most challenging because fluids can easily change direction, velocity, and pressure. To design the wing of an airplane, for example, the engineer needs to accurately calculate the lift and drag forces, taking into account all the possible environmental scenarios to ensure the design doesn’t fail. This often means building and discarding as many as 100 models before getting the right configuration—a process which requires a lot of time and money.

This is where computational fluid dynamics, also known as CFD, comes into play. When an engineer is tasked with building a winning race car, creating a more efficient aircraft, or designing the exhaust nozzle of a new rocket engine, CFD plays a key role.

Sign up and check out our SimScale blog for much more!

Read More Now

“Introduction to CFD” with SolidProfessor

The course aims to help you get started on your journey to learn the theoretical and practical applications of CFD.

At the beginning of this course, the theory will be front and center. Together with the instructor, participants will discuss the steps of the CFD process, the fundamental governing equations, the finite volume method, and important concepts related to meshing, boundary conditions, and turbulence modeling.

The theory is the foundation for understanding the practical applications of CFD, which will be the focus of the second half of this course. With interactive case studies and hands-on exercises, students will be able to set up their very own CFD simulation using SimScale. By the end of this course, successful students will develop a solid foundation in CFD theory and understand how to use the SimScale cloud-based platform to upload a CAD model, create a mesh, apply boundary conditions, obtain a CFD solution and visualize and interpret the results.

Interested? Sign Up!

The “Introduction to CFD” course can be accessed as part of the SolidProfessor’s Standard, Professional, and Premium memberships. Simply create an account and sign up for the course!

Register For The Course

The post Learn to Solve Fluid Flow Problems with SolidProfessor and SimScale appeared first on SimScale.

This paper addresses the topic of pedestrian wind comfort, from origin and
definition to wind comfort analysis, criteria, and example case studies; all meant to
form an in-depth understanding of the field.

Download Whitepaper

For that reason, the team of application engineers at SimScale make sure to validate all the major features that are rolled out over time, comparing the simulation results to analytical or experimental data. Recently, we used experiments from the Architectural Institute of Japan (AIJ) to validate the results gained from the SimScale platform.

Pedestrian Wind Comfort Architectural Institute of Japan (AIJ) Pedestrian Wind Comfort Experiments

The Architectural Institute of Japan (AIJ) is a Japanese professional organization for architects, building designers, and engineers. It was founded in 1886 and has gathered over 38,000 members since. It publishes several journals, technical standards for architectural design and construction, and research committee studies.

The wind analysis test case for this validation was taken from the “Guidebook for Practical Applications of CFD to Pedestrian Wind Environment around Buildings”, published by AIJ in 2008, which sets the standards for cross-comparison between the results of CFD predictions, wind tunnel tests, and field measurements, and helps validate the accuracy of CFD codes for pedestrian wind comfort assessments.

Pedestrian Wind Comfort Case E: Wind Analysis in an Urban Area

The case being validated is Case E, which is a simplified geometry of a complex of buildings. The urban area model treated here was an actual city block in Niigata city, Japan, with low-rise houses jammed closely together and one target high-rise building at 60m high. Wind tunnel experiments at 1/250 scale were performed on this model in a turbulent boundary layer with a power law exponent of 0.25.

Out of the many scenarios presented in Case E, the impact of the winds from the north, east, south, and west was used to validate the CFD code of SimScale.

The SimScale CFD results were compared to the experimental results and were found to have a good correlation. Some underprediction was seen in the k-epsilon models in the strong wind regions and underprediction in the wake regions, but is a known trait of the k-epsilon model and is within an acceptable range. However, it should be taken into consideration when evaluating results.

Analysis Domain and City Geometry

The geometry was converted into STL using Bear File Converter and imported into SpaceClaim to turn the mesh into solids. The solids were then subtracted from a larger volume which was to be the surrounding fluid domain. To do this, a certain amount of cleaning had to be done, including creating thin cylinders on edges that touched but weren’t intersected. This was the cause of some CAD issues external to SimScale.

The geometry was then imported to SimScale. The size of the bounding box was 2 x 2 x 1 km.

Mesh

A parametric hex-dominant mesh was used, where region refinements were placed on the city itself and further surface refinements on the building surfaces. The floor was refined with a thin region refinement. The floor and the buildings had two layers inflated relative to the cell size.

The above images show that the mesh was quite coarse, with a cell density of 50/km. The cell count for the mesh was 30 million cells.

Simulation Setup

The model type was steady-state with the k-epsilon turbulence model. The standard air material was used and the solution was initialized using potential flow.

These validation simulations for each wind direction were all set up similarly, with only the inlet, outlet and side faces altered depending on the direction. The inlet was defined using a CSV upload for velocity, turbulent kinetic energy and dissipation rate, and a zero-gradient pressure condition. The outlet was a zero-pressure outlet and the top and sides were slip walls. The buildings and the ground were no-slip condition walls.

CFD Analysis Results

To compare the CFD wind analysis results to the experimental data, the velocities were normalized with the value of velocity at the inlet at a height of 15.9m. The measurements were taken at points listed in the AIJ guidebook.

The CFD results obtained from the SimScale platform were plotted against the experimental results to see the correlation.

The correlation between the AIJ experiments and SimScale results was highly linear, with a majority of the points being within 0.2 in relative velocity. To see how the results compared in more detail, the results were plotted against the point numbers so they could be compared to the velocity slices.

The images below show the velocity comparison for the case of a strong northerly wind. For a detailed analysis of other cases, please refer to this simulation project in the SimScale Public Project Library.

These results show that, as the correlation plot suggested, the CFD simulation with SimScale and the wind tunnel experiments produce very similar data. It can be observed that in regions of particularly high velocity, the simulated results may show a slight overprediction. This, however, is considered more desirable than underprediction, as this is where pedestrian wind comfort is likely to be an issue. On the other hand, the points located in wake regions tend to be underpredicted. This is a known trait of the k-epsilon model, and since pedestrian wind comfort problems rarely occur in the wake regions, this is not normally considered an issue. Examples of this are most strongly seen in the westerly wind scenario.

Conclusion

Buildings in urban areas have complicated shapes and are distributed in an irregular manner, making physical testing difficult and expensive. With the accuracy of CFD codes steadily increasing, simulation has become a viable substitute, and it has been adopted by architecture and construction companies all over the world for assessing pedestrian wind comfort, wind loads on buildings, skyscraper aerodynamics and more. A strict verification and validation of simulation results, however, remains critical for engineers to be able to use the obtained data with confidence and base important design decisions on it.

Download our ‘Tips for Architecture, Engineering & Construction (AEC)’ white paper to learn how to optimize your designs!

Download Now

If you enjoyed studying this validation project, you might be interested in another CFD simulation based on the AIJ experiments: Case D: High-Rise Building in City Blocks. Both projects can be copied for free from the SimScale Public Projects Library and used as templates for your own analysis. If you’d like to learn more about the SimScale cloud-based platform and its capabilities, download this features overview.

The post Pedestrian Wind Comfort: CFD Wind Analysis & Validation with Experiments appeared first on SimScale.

Green Building Standards: ASHRAE 189.1 and LEED Certification

LEED (Leadership in Energy and Environmental Design) is a rating system developed by the U.S. Green Building Council, regulating the design, construction, and maintenance of green buildings. It is the most widely used green building rating system in the world. The LEED certification is credit-based, allowing projects to earn points across several categories.

Another standard that is helpful to keep in mind is the ASHRAE 189.1, which is the “standard for the design of high-performance green buildings”. It provides architects and engineers with a standardized approach towards designing and operating green buildings, filling the gaps of evolving building codes. It is based on other existing ASHRAE standards (such as the Energy Standard 90.1, Ventilation Standard 62.1, and Thermal Environmental Standard 55) while applying a more defined set of sustainability criteria.

Active and Passive Design Strategies

Several categories for LEED certification include design aspects relevant to energy use and air quality, making it imperative for green building designers to find the right combination of active and passive design strategies.

Active design strategies use energy-consuming mechanical systems to maintain the building, while passive design strategies rely on natural energy sources. High-performance building design places particular importance on investigating passive strategies while trying to downsize the active systems as much as possible.

Passive strategies include the use of natural ventilation and shading to provide air movement and reduce indoor temperatures and the use of solar heating to ensure thermal comfort while taking into account regional climate and ventilation timing.

HVAC Design for Green Buildings: How Can CFD Help?

In that regard, having a high-performance HVAC system is crucial. It is one of the key components of green building design, as it determines the building’s energy efficiency, life-cycle performance, and occupant productivity.

Here, the early concept and design stages are particularly important, having the largest impact on cost and performance of the HVAC system and the future building as a whole. In order to ensure compliance with relevant green building standards, a reliable validation tool needs to be used during these early design stages.

Computational fluid dynamics (CFD) is one such tool and has been adopted by many engineering companies in the AEC industry. It is a field of fluid dynamics that uses numerical analysis to simulate and solve problems involving fluid flows. With its help, mechanical and HVAC engineers can gain detailed insight into the airflow patterns, optimizing the building design to get the highest possible LEED certification.

CFD can be successfully applied to ensure compliance with many relevant aspects of green building standards associated with air flow, such as thermal comfort, indoor air quality, energy consumption and efficiency, and more. This can be highly beneficial for the planning of green building projects and in obtaining a LEED certification, where sustainable building design, optimized energy performance, and air comfort play a crucial role.

Green Building Design Workshop with Practical Examples

Watch the Workshop Recordings

In order to bring the CFD simulation technology to more green building designers and engineers, Qatar Green Building Council (QGBC) and SimScale have organized a free training focused on teaching the application of fluid flow simulation in the HVAC and AEC industries.

There is no prior knowledge or software required to follow this webinar. SimScale is a cloud-based platform, which means that all the required simulation features are accessible directly from a web browser.

Sign up & check out our SimScale blog for much more!

Read More Now

Session 1: Energy-Efficient Designs for Buildings

In the first session of the workshop, you will discover the fundamentals of fluid flow simulation and learn how it can be used to meet the requirements of the LEED certification. We analyzed a case study showcasing how natural ventilation system design can be validated. The simulation project template used in this session can be accessed here.

Session 2: Thermal Comfort for Occupants

The second session focuses on the topic of thermal comfort. You will learn how to use CFD simulation to ensure compliance with different standards for thermal comfort in buildings. We looked into a case study where thermal comfort was optimized in a classroom. A public project similar to the one presented in this session can be found here.

Why Investing in Green Building Design Is Worth It

A common misconception about green building design is that it is expensive. This perspective, however, focuses solely on the up-front cost, failing to consider the overall life-cycle cost of the building. While it is true that most green buildings cost a premium of <2%, they yield 10 times as much over the entire life of the building. [1] The cost savings come from the efficient use of utilities, decreased energy bills, higher worker productivity, and more, exceeding the additional up-front costs by 4-6 times. Studies of the commercial real estate market have also found that LEED-certified buildings achieve significantly higher rents, sale prices, and occupancy rates. [2]

If you want to read more about how CFD simulation helps engineers and architects improve building performance, download this free white paper.

The post Green Building Design: How to Obtain LEED Certification with CFD appeared first on SimScale.