Problems With Heat Exchanger Specified Heat Rate In Constants?

Posted on February 21, 2012 by Ben Keiser

Using “Specified Heat Rate In Constants” for the thermal model of heat exchangers can often cause problems in system models.  The reason why is because this thermal model type causes the heat exchanger to act like an “assigned heat input” junction as does an assigned flow junction does for providing constant flow rates.  Another problem is that this thermal model can cause unrealistic temperature changes across a heat exchanger.  When the heat rate is specified and the mass flow rate and heat capacity are calculated based on the system solution, the temperature change will be whatever is required to maintain the specified heat rate.  This is analogous to the way an assigned flow junction will add whatever pressure is necessary to maintain a specified flow.

It is always best to use other heat exchanger thermal models and the heat rate for the heat exchanger will be available as an output that can be compared against the original desired heat rate.

If the heat rate is known as well as a function of flow rate, then the thermal model “specified heat rate in vs. flow” can be used.  One would enter this information into a table just like establishing a resistance curve as a pressure loss model.  Use the zero point as the first data point (zero flow rate and zero heat input).  Then enter the heat rate and mass flow rate that is known, and finally add one more data point where the flow rate is doubled and the heat rate is quadrupled.  This will allow the heat exchanger to modulate its heat rate with the system flow rate and can produce more accurate results.  The screenshot below contains the data needed for the curve fit as well as the generated curve in the heat exchanger specifications window itself.

 

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My 50th Anniversary Visit to the Site of John Glenn’s First American Flight Into Space

Posted on February 20, 2012 by Trey Walters

Many of you probably saw in the news that today, Monday, February 20th, is the 50th anniversary of John Glenn’s flight into space. The flight was aboard a Mercury-Atlas rocket dubbed Friendship 7. This historic event was a significant step on the way to the Apollo missions to the moon.

By good fortune the NASA contractors at Kennedy Space Center had scheduled an AFT training class last week, and I traveled to Florida to teach the class. I took some time to tour the Space Center and Cape Canaveral one evening and was able to visit Complex 14 where the launch took place.

The rocket booster for Friendship 7 was a General Dynamics Atlas rocket. Of special interest to me personally was that I spent several years working on Atlas rockets at General Dynamics. This was a couple decades after John Glenn’s flight. In fact the Atlas rocket liquid oxygen propellant line was my first introduction to waterhammer and where I gained much of the knowledge that undergirds our AFT Impulse™ waterhammer software. It is also where I met and worked with Jeff Olsen who is currently AFT’s Vice-President of Technology. Like me, Jeff is also a former rocket engineer.

Complex 14 was dismantled many years ago and today is just a remnant. Below is a photo I took last week of the launch complex at Cape Canaveral. Also below is a photo of me next to the launch site.

A photo I took of Cape Canaveral Complex 14 with John Glenn’s parking spot freshly painted – the launch site is in the far back.

Me in front of the Cape Canaveral Complex 14 launch site

 

Astronaut John Glenn, the Friendship 7 Mercury Capsule is shown being launched from Cape Canaveral, Florida on February 20, 1962. (AP Photo)

Today the Atlas rocket is part of Lockheed Martin’s space offerings. Atlas V rockets are launched from Cape Canaveral’s Complex 41 and as luck would have it there was an Atlas V launch scheduled last week as well. I and some of the engineers in the training class gathered one evening to watch the launch from the fourth floor of their office building. But my luck ran out that day and the launch was scrubbed and postponed due to wind.

A sign on the doorway to the Cape Canaveral Complex 14 blockhouse with a history of the General Dynamics Atlas rocket.

 

I also got to see some of the infrastructure remaining from the Space Shuttle program including a visit inside the massive Vehicle Assembly Building where the Space Shuttle Orbiter Atlantis was being prepared for its new life in a museum (see photo below).

A question we discussed frequently last week was what is next for America’s manned space program. We seem to have lost our way and our will. I hope we can find it and reach for the stars once again. It makes all of us at AFT proud that our software is part of this effort.

A special thanks to the engineering staff at Kennedy Space Center who hosted me last week!

I took this photo of the massive VAB (Vehicle Assembly Building) – which awaits the next generation of heavy lift launch vehicles as its Apollo – Saturn V and Space Shuttle days are now behind it. It is 526 feet (160 meters) tall and one of the world’s largest structures by volume. For scale see the fence and vehicles at its base. The orbiter at the right is a mockup on display.

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Why I Like Bill Gates More Than Steve Jobs

Posted on January 31, 2012 by Trey Walters

I have an iPod – to which I am very attached. I have had my iPod Nano for a couple years now. All of my kids and my wife have iPods. I hike frequently in the Colorado Mountains near where I live and I can’t do it without my iPod. I can’t work out at the gym without my iPod. I can’t drive my car without my iPod.

I have an iPhone – to which I am very attached. I have had my iPhone for about 6 months now. It goes with me everywhere and – along with AT&T – was a reliable tool for me in Australia and Asia late last year. My wife has an iPhone. All the sales and technical staff at Applied Flow Technology have company-provided iPhones.

For my iPod and iPhone I frequently download music on iTunes. iTunes holds my entire precious music library.

I am emotionally attached to my iPod and my iPhone.

My first experience with a graphical user interface was on an Apple Macintosh. Although I never owned an Apple computer, at my first engineering job I worked regularly on a Mac for five years. It was at my second job where I first became acquainted with Microsoft Windows. Version 3.1.

My first PC was an 8086 IBM clone (from Dell) running Microsoft DOS 3. Command lines. Arcane. High barriers to usage. Definitely the tool for an engineer.

When Steve Jobs passed away a few months ago there was understandably a lot of discussion in the media on his contributions to society and the marketplace. Like many of you I read a number of articles on Steve Jobs and watched several news programs and documentaries. Somewhere along the way I picked up on Steve Jobs’ apparent disdain for Bill Gates and Microsoft.

That sentiment has been bothering me ever since.

Today Apple is the most valuable public company in the world. Microsoft – which not too long ago held that distinction – has, in the opinion of many, seen its better days.

Steve Jobs created Apple out of a garage and was instrumental in building that into a multi-billion dollar company. Twice. Once originally and then, after being kicked out of his own company for ten years, when he saved Apple from potential bankruptcy in the 1990’s. During that time away from Apple he was an early investor in Pixar – another multi-billion dollar company which he helped build. A person who helped create two and arguably three multi-billion dollar companies is one amazing individual. Steve Jobs was amazing, no doubt.

However, Steve Jobs’ (and Apple in particular) always seemed to be about control. His lack of an open architecture for the Apple computer was a big turn off for me. I much preferred the openness of the IBM “PC” so my preferences went that way – along with a huge percentage of the marketplace. Bill Gates and Microsoft were instrumental in propagating the graphical user interface to the masses – both in business and consumers.

Bill Gates and Microsoft is what made Applied Flow Technology possible.

But that is not the only or even the main reason why I like Bill Gates’ more than Steve Jobs’. Microsoft was always open and supportive of outside innovators (as long as they did not compete with Microsoft – a subject for another day!).

Steve Jobs’ disdain for Bill Gates and Microsoft was based, I believe, on creativity. That Microsoft was not creative. And as far as that goes he was mostly right. Apple has been a more creative company than Microsoft.

However, Microsoft has been a more open company than Apple and that has allowed outsiders to achieve their own independent success.

Apple invented the PC but they lost their lead to IBM heritage PCs because of Apple’s closed system mentality. The PC and Microsoft achieved dominance because they were on an open platform, and Microsoft was further open by developing and providing tools to an army of independent software developers who built applications for the PC to run on their Windows operating system.

For the first time the world opened up to small companies (even one-person companies) who could cost-effectively leverage Microsoft’s efforts and tools to influence their own industries and build their own new companies. The software tools developed by these small companies allowed other small non-software companies to exist and thrive. There was and is a multiplier effect from Microsoft’s efforts that has allowed countless individuals and new companies to find success.

In parallel, Microsoft’s tools allowed large companies to collaborate at a level never possible previously. This provided numerous efficiencies in large companies that helped them become more capable and competitive.

I liked Steve Jobs because he made our lives more enjoyable. I like Bill Gates more because he has made our lives more successful.

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Integrating Component and Fitting Losses into a Single Pipe on the Workspace

Posted on January 31, 2012 by John Rockey

Many components, such as isolation valves, elbows, and adjacent area changes, do not need to be modeled graphically when a simple k factor will suffice. In these cases, the Fathom user can simplify and avoid unnecessary workspace clutter by integrating this data into a single pipe specification, using the Fittings & Losses tab.

Fathom has a built library of component loss data provided by Miller, Crane, and Idelchik. The Fathom user can quickly and easily pick from a database of components, enter the quantity, and click OK. It is important to note, however, that Fathom uses the size of the pipe to get the correct k factors, so the Fittings & Losses dialog will not be available until a pipe size is specified in the Pipe Model tab.

 

 

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Backup Files

Posted on December 29, 2011 by David Jackson

All AFT Products automatically generate backup files each time you save your model. Backup files will be saved to the same location you have saved your model file to. They will have the exact file name as your model, but rather than having the extension *.fth, *.aro, *.imp, etc., they will have the extension *.001, *.002, *.003, etc.

Every time you click save while working in your model, a new backup file will be created. If the maximum number of backup files already exists, the new backup file will overwrite the oldest backup file. The maximum number of backup files created can be set in the General Preferences window.

 

In order to use a backup file to open a previous version of your model, simply rename the model file by removing the *.001, *.002 and replacing that extension with the extension of the product you are using (Fathom = *.fth).

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It’s the Economy Stupid. Or Is It?

Posted on December 28, 2011 by Trey Walters

A few months ago I attended a CEO forum in Colorado where a big topic on the minds of the 1000 CEOs in attendance was the state and direction of the US and global economy. The keynote speaker Brian Beaulieu began his presentation with this assessment of the economy from TIME magazine:

The U.S. economy remains almost comatose. The current slump already ranks as the longest period of sustained weakness since the Great Depression. Once-in-a-lifetime dislocations will take years to work out.

 Among them: the job drought, the debt hangover, the defense-industry contraction, the banking collapse, the real estate depression, the health-care cost explosion and the runaway federal deficit.

What was interesting was what was revealed next – the date when the above was written. It was from September, 1992!

The media – especially in the USA – is in the business of making every situation sound extremely ominous. If you are interested here is a link to Brian Beaulieu’s presentation.

An informal survey at the CEO forum (we were asked to show hands) indicated the vast majority had job openings. I have heard this over and over in recent months. Companies are hiring.

Are there people displaced by the current economic challenges? Yes, of course. The economy is a very dynamic thing. But the story is not so much about jobs destroyed but of jobs created. Jobs are always being destroyed. In the USA it is 15-17 million jobs destroyed every year – even in a healthy economy. When job growth occurs it is because more jobs are created than destroyed so there is net growth. Right now jobs are being created – just not enough to significantly offset those being destroyed.

A recent article by Exxon Mobil “Where the jobs are” discusses the huge potential in the USA to create new jobs in the energy sector. A recent article in BusinessWeek “Hope for American Manufacturing—and Maybe Jobs” discusses the rising wage scale in offshore manufacturing and how manufacturing jobs are returning to the USA. Things are not as bleak as the media continues to portray.

Many new companies are started during times of economic challenge. Applied Flow Technology was started during a recessionary time in 1993. We may not see the impact of some of these new startups for many years.

All of this is just a reminder – if we needed a reminder – to view the media’s presentation of the news with great skepticism.

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The Quickest Way to Learn AFT Products

Posted on November 29, 2011 by Ben Keiser

After you receive your AFT software, you will probably wonder how to learn the software quickly so you can begin using it.  AFT provides a very handy Quick Start Guide for each software product in English Units and SI Units.  These quick start guides are short, concise, would take maybe a day of your time, and are extremely powerful to assist you in producing highly accurate and advanced models!

With larger companies, sometimes the AFT software will go straight to the IT department for installation and the engineer may never see the hard copy of the quick start guides.  Not to worry!  AFT provides PDF versions of our quick start guides when the software is installed.  One area to find the quick start guides is in the “User Guides (PDF Format)” start menu item in each AFT application folder.  The second area to find the quick start guides is from the “Help” menu from the software program itself.  Go to Help, User Guides (PDF Format), Quick Start, and then chose either English Units or SI Units.  Also, inside each AFT product folder, there is a help file that contains many more excellent walk-through examples to help build ones modeling skills even more!

The content of each quick start guide is rich with information about the fundamentals and pipe flow analysis concepts of each software product.  You will learn so much from just a few short examples in each quick start guide that you will be able to build and model complex pipe networks and analyze multiple scenarios of a project in a very efficient manner.  The quick start guides will teach you the basics of the fundamental function of pipes and junctions, how to size a pump/compressor/fan or use heat transfer in a model, how to use extremely powerful features like “Global Pipe Edit,” “Global Junction Edit,” and “Scenario Manager” which every engineer needs to know how to use to save lots of time!

From one engineer to another, I highly recommend taking a day to go through the quick start guide.  It will add so much value to your pipe-flow modeling abilities that it will be unFATHOMable as to what you will be able to do with it!

 

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Thankful for the Opportunity to Shape a Changing World

Posted on November 29, 2011 by Trey Walters

Wherever I go I see change. China is undergoing massive change in a relatively short period of time which has impacted Western nations both positively and negatively – as well as the rest of the world. China’s growth in manufacturing is impacting Australia in a huge way and driving much of the Australian economy through accessing its abundant natural resources.

As we look back on the American Thanksgiving holiday I am currently on a lengthy visit to Australia and Asia training customers in the East and meeting new prospects. And seeing the changes first hand. My family is along with me and we celebrated Thanksgiving in Thailand far away from our home in beautiful Colorado. I am thankful for many things among which are my family, health and access to education and resources. I also am particularly thankful at the moment for the chance to observe and participate in shaping
these changes in the world.

The “Occupy Wall Street” movement in the USA and some European nations is hard to precisely pin down, but one common thread relates to jobs. Another common thread is the demand for structural changes in the economic system. In western Australia no one seems to care or have time to occupy anything – their unemployment rate is near zero and they cannot find enough people to fuel their surging economic growth. The class I taught in Perth had engineers from Chile, South Africa, U.K., Iran and Vietnam who had re-located to Australia for the work. In China the demand for infrastructure projects is growing at an incredible pace to support their economic growth. Jobs too are plentiful. Thailand is a production mecca and its traditional openness to outsiders is serving it well as it attracts manufacturing work from all over the world.

We engineers of course play an integral role in the changing technology, improved efficiency and production of goods and services which impact society in so many ways. It is our responsibility to guide the world’s growth by building new systems that are reliable, safe and efficient. It is also our job to innovate. To find ways to do the next project better than before. And to develop new products and processes to make the world a better
place.

Especially in places like China and Australia where infrastructure is being put into place that will last for many years to come, it is all the more important to put into place engineering processes that promote safety, reliability and efficiency. Such infrastructure inevitably involves the transport of fluids. We work hard at AFT to provide tools which
make the transport of fluids safer, more reliable and more efficient. Engineers in the USA and internationally are seeking such tools to help them do the best job possible.

It is a truism that protesters like those in Occupy Wall Street are rarely seen in times and places where the economy is solid and opportunities are abundant. The West and the USA in particular suffered an economic shock unlike anything seen in most of our lifetimes. Jobs are not the issue per se. Who wants to support job growth in typewriter or buggy whip manufacturing? Those are dead industries of the past.

In pursuit of job creation, the key in the West and USA is quality jobs such as engineering and high-margin/high-tech manufacturing positions. The key to quality job creation will be knowledge and innovation – these will undergird the industries of the future.

Ultimately it is the engineers and knowledge professionals of the world who will create these industries. And the jobs that go with them.

 

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How to Fill as Quadratic

Posted on October 27, 2011 by John Rockey

Filters and screens impose a pressure drop that varies with flow rate. The variation is non-linear, but manufacturers will often provide only one data point for pressure loss at the design flow rate. Using a single point, or constant pressure drop, can produce significant inaccuracies in your model. With this in mind, AFT offers the “Fill As Quadratic” option for entering loss data.

 

 

Using only a single point, “Fill As Quadratic” will create two additional points for you. This first is simply 0,0; zero flow produces zero pressure drop. The second point is 2 x Flow and 4 x Pressure Drop. A curve is then fit through all three points and there you have it; a quadratic loss profile from only one data point. By using values along the curve, more realistic losses can be modeled for a wide range of flow rates.

The Fill As Quadratic feature is available in AFT Fathom, Arrow, and Impulse.

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AFT Around the World

Posted on October 27, 2011 by Jeff Olsen

In early October, I conducted a 5-day training seminar in Lima, Peru. There were seven different companies represented from Peru and Chile.

It is always interesting to see the variety of applications for AFT software and Peru was no exception where many of the engineers are involved in mining operations. Peru is a leading producer of copper, gold, silver, phosphate and potash with over $16 billion in exports in 2009. The engineers at the seminar had a variety of active project responsibilities. These ranged from long transport pipelines, to storage and transfer systems, to refining and process facilities.

The course emphasized AFT Fathom and modules, including the slurry module. The week finished with two days of training on AFT Impulse and water hammer examples.

The ability to add custom piping and fluids interested the engineers as they use specialized components in their systems. Using the XTS and GSC modules allowed the engineers to model tanks filling and draining, valves opening and closing, and other system operations. They also focused on using Impulse to model systems and locate potential water hammer problems. Components such as vacuum breaker valves and gas accumulators can be added to a model to evaluate their benefits.

Macchu Picchu

A View of Machu Picchu

One of the benefits of teaching seminars all over the world is being able to visit some incredible landmarks. In Peru, I spent two days visiting Machu Picchu, Ollantaytambo and the Sacred Valley which was amazing. To see the natural beauty of the area with the mind-boggling engineering and architectural feats was awe inspiring.

Prior to that, in August, I traveled to Tel Aviv, Israel to conduct a 5-day training seminar for the Israel Air Force. Eight engineering officers learned fluid dynamic fundamentals and system modeling using AFT Fathom, AFT Arrow and AFT Impulse.

AFT applications are used by the Air Force on both ground-based and airborne systems. The engineers use AFT Arrow, which models gas and compressible fluids, to model the environmental systems critical to the pilot’s safety. Fuel transfer systems have been modeled using AFT Fathom. Hydraulic lines on fixed-wing and rotary-wing aircraft are also analyzed using AFT Fathom and AFT Impulse.

By the end of the five days, the engineers new to AFT products were building detailed models and the experienced AFT users had learned many tips and best-practices. It is always amazing to see the many different applications of our software – from large to small, either in motion or stationary, from very hot to cryogenic.

Again, I was able to visit several areas in the Holy Land including the West or Wailing Wall in Jerusalem, Nazareth and Masada. Floating in the Dead Sea in the middle of the summer (well over 100 deg F, 40 deg C) was like getting into a hot bath – I didn’t stay in long.

Contact us for more information on scheduling training classes around the world.

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