Let’s Cool Things Down With Heat Transfer Equations

When it comes to cooling products, we get many questions on what would be the best method. Generally with larger parts with heavy mass and large surface areas, we would recommend the Super Air Amplifiers, Super Air Knives or Super Air Nozzles. We have to look at many factors to determine the correct method, but if look at the mass of the part, the ambient conditions, the speed of the conveyor, and the change in temperature, we can get a good start in setting up an application.

In determining a good estimate, we use a couple of heat equations to help. As with any customer, you want to make sure you have as much information to get a good platform to start. We use two equations to begin. The first equation is used for the product that needs to be cooled.

Equation 1

q = m * Cp * (T2 – T1)

Where:
q – heat (BTU) or (Kcal)
m – Mass (Lb) or (Kg)
Cp – specific heat (BTU/Lbm oF) or (Kcal/Kg oC)
ΔT – Temperature (oF) or (oC)

Once we have the amount of heat that we need to remove, then we can look at the product to cool it. With Super Air Amplifiers, we use an equation that is used in fan cooling. This is the second equation.

Equation 2

h = 1.08Qs(T2 – T1)       OR                h = 0.33Qs(T2 – T1)

Where:
h – heat rate (BTU/hr)                                   h – heat rate (Watts)
Qs – Flow (SCFM)                  OR                   Qs – Flow (NM^3/hr)
ΔT – Temperature (oF)                                  ΔT – Temperature (oC)

 

As an example, we have an aluminum part that came out of a baking oven at 400 oF (204 oC), and we want to cool the part down to 100 oF (38 oC) for handling.  If we give the part a mass of 20 lbs. (9.1 Kg), we can determine how long we would need to cool the part. The specific heat, Cp, of aluminum is 0.22 BTU/Lbm oF or Kcal/Kg oC. Applying this to Equation 1, we get the following:

q = 20 lbs * (0.22 BTU/lb/oF) *(400 oF – 100 oF)

q = 1,320 BTU

Or

q = 9.1 Kg * (0.22 Kcal/Kg/ oC) * (204 oC – 38 oC)

q = 332 Kcal

This tells us how much heat we would need to remove in order to handle. To keep going along with this example, we will use the 120021 Super Air Amplifier. With the large amplification level, it has a flow of 436 SCFM (740 NM^3/hr) at 6” away. To produce that volume, it only uses 8.1 scfm of compressed air at 80 psig. There are a couple of things that we should consider with our estimation. Ideally, we will want to be at a distance where the velocity will be between 1,700 to 2,500 fpm (8.6 to 12.7 mps). This gives us the best velocity for the maximum cooling rate. Depending on certain situations, you may have to add a little more time for cooling if the velocity is too high or too low. With the 120021 Super Air Amplifier, a distance of 18” from your target will give you a velocity close to 1,850 fpm (9.4 mps). The other consideration is the rate of heat loss. The bigger the temperature difference, the faster it will cool. As you get near the target temperature, the rate change becomes smaller. With that, I usually take the average temperature as an estimate. Using our example above, it would be (400 + 100)/2 = 250 oF, or (204 + 38)/2 = 121 oC. The other estimation will be the temperature of the ambient air. It will be cooler as it first hits the target and then heat up. If we add roughly 7 oF (4 oC) to the ambient air temperature because of the velocity, then the ambient temperature would become 68 + 7 = 75 oF (20 + 4 = 24 oC). With Equation 2, we will get the following:

h = 1.08 * 436 SCFM *(250 oF – 75 oF)

h = 80,404 BTU/hr

Or

h = 0.33 * 740 NM^3/hr * (121 oC – 24 oC)

h = 23,687 Watts or 20,372 Kcal/hr

With Equation 1 and Equation 2, we can estimate the amount of time needed to cool the part. In having to remove 1,320 BTU at a rate of 80,404 BTU/hr, the equation will give us 1,320 BTU/ (80,404 BTU/hr) = 0.016 hr or 1 minute.  In metric units, 332 Kcal/(20,372 Kcal/hr) = 0.016 hr or 1 minute. This means that we will have to keep the target in the air stream for about 1 minute. Depending on the geometry of the part, the angle of the amplifier, and the speed of the conveyor, we may need multiple Super Air Amplifiers. As I mentioned before, these are estimations, but it will help in getting an idea for your project. You can always contact the Application Engineers at EXAIR for any help.

Cooling with Air Amplifiers

Cooling with Air Amplifiers. The Super Air Amplifiers are mounted across the top of this connecting rod/piston assembly. 

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

“Deluxe” and “Premium”

These are two words that have been important parts of my vocabulary for most of my life. As a long time fast-food burger connoisseur, these words mean I’m getting something other than a hastily cooked ground beef patty on an enriched white flour bun that may or may not have been sitting under a heat lamp for a specific period of time. If you’re anywhere near as familiar with drive-thru cuisine as I am, you’ll know that “Deluxe” usually means a variety of toppings has been added to an otherwise relatively plain sandwich…it’s been “run through the garden,” if you will. And “Premium” can mean anything from a special bun, gourmet cheese, up-scale meat, and/or the addition of bacon…they ALWAYS get me at bacon…

I don't know what the knife and fork are doing there, but whatever...

I don’t know what the knife and fork are doing there, but whatever…

EXAIR’s Industrial Vacuums are also available in Deluxe and Premium Kits. Now, if you’ve already got a drum, our standard Kits will quickly and economically turn that drum into a powerful, fast, and efficient vacuum system, without the need for anything fancy. If you’re looking for complete, comprehensive clean up solutions, though, our Deluxe Kits add a drum dolly, a tool holder, and additional tools. The Premium Kits also include a durable steel drum and a set of Heavy Duty Aluminum Tools.

Whatever your needs are, we’ve got an efficient, quiet, durable, long-lasting, maintenance-free vacuum system for you. Our Reversible Drum Vac will empty…or fill…a 55 gallon drum in 90 seconds (tested with water.) Our new High Lift Reversible Drum Vac pumps that same 55 gallons in just 85 seconds, with up to 15 feet of suction head. Then, of course, the Chip Trapper uses our Reversible Drum Vac technology to filter and extend the life of your machine tool coolants, lubricating oils, etc.

Reversible Drum Vac, High Lift Reversible Drum Vac, Chip Trapper

(Left to Right) Reversible Drum Vac, High Lift Reversible Drum Vac, Chip Trapper

For solids vacuuming situations, our Chip Vac picks up wet or dry chips, debris, etc., and deposits them directly into the drum. This is the function of the Heavy Duty Dry Vac as well. It’s more powerful than the Chip Vac, for use with heavier debris, and it’s made of a hardened alloy for superior abrasion resistance. The Heavy Duty HEPA Vac delivers the same high performance, with a high efficiency filter for total dust containment.

(Left to right) Chip Vac, Heavy Duty Dry Vac, Heavy Duty HEPA Vac

(Left to right) Chip Vac, Heavy Duty Dry Vac, Heavy Duty HEPA Vac

Whatever your Industrial Vacuum needs are, we’ve got a solution for you. And if you order before the end of March, we’ll throw in a FREE Vac-u-Gun…our lightweight and portable vacuum gun, blow gun, and transfer tool, all in one. Call me to find out more.

Russ Bowman
Application Engineer
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tiktok 5 photo courtesy of Kirrin.  Creative Commons License

Tourney Time!

This week begins my favorite time of year – college basketball madness!

Basketball hoop

It’s Awesome baby, with a capital A!

Like many of us around the country, my fan loyalty resides with a relatively small, local college that has seen a lot of program growth in recent years – Xavier University. For example, during the 2003-2004 season, the team was ranked preseason top 11 in the country but stumbled along the way and found themselves at 10-8 with a pivotal game against their in state, conference rival. They ended up losing the game and the players held a “team only” meeting afterwards so the seniors could, let’s just say, “focus” the team on their goals. Whatever was said in that locker room worked, as the team went on to finish the regular season with a 9-1 record and win 4 conference tourney games in 4 days (first team to ever tackle this feat) to capture the automatic bid to the national field of 64, where they eventually lost by only 3 points in their first ever Elite 8, to a certain team from Durham, NC. (It was the REFS fault and no I’m not bitter LOL).

In 2008 the team was facing a similar challenge as they had lost several close games and were now again faced with needing to win 4 games in 4 days to get the automatic conference title bid. They went on to secure the bid and were able to reach the Elite 8 again for the 2nd time in 4 years but their run ended with a loss to the #1 seed in the region. The school has now joined a larger conference which is great for national notoriety and recruiting but also brings a higher level in competition, either boosting or damaging their tournament resume.

This year has followed suit to previous years as the team didn’t perform up to expectations and spent much of the latter part of the regular season on the proverbial “bubble”. After each win or loss, the prognosticators would move them from a “lock” to the “bubble”, or even more confusing, “still has work to do” category. All that mattered was just win and let the rest take care of itself. The team did just that as they went on to make the finals of the conference tournament but were easily handled by the first place team and eventually lost.

The selection committee has rewarded their conference affiliation along with conference tournament success and ranked them as a 6 seed for this years national championship tournament (a little high in my opinion but I’ll take it!) playing the winner of one of the play-in games.

Who knows what tournament success or failure lies ahead but that is what makes this time of year so awesome. Even when my team loses, there is always a local team, an underdog or the year’s “Cinderella” that grasps the country’s attention and makes it hard to root against them. Since we are in Cincinnati, many of our folks live in Kentucky and the Wildcats prove their wide reach among many of our Ohio based people as well. It makes the office banter and challenges and trash talk more interesting when pitting the hopes of a small “bubble” team up against a behemoth like Kentucky. We would be remiss not to mention the other behemoth with a huge fan base in this neck of the woods, Ohio State. We cannot forget our loyal base of University of Cincinnati Bearcats, who have provided us with some stellar employees, though not much of a basketball team this year (I’m a Xavier fan, remember?). And with the late breaking news from last night’s winning Dayton Flyer team, we have some solid regional representation in the tourney year.

Wow, now that I think about it, we’ll be lucky to survive the next few weeks without a bit of office bloodshed. At the very least, a small skirmish is certain to happen ;-).

Here at EXAIR we have a great team too! From the production team all the way up to management, we understand that we need to remain focused on our main goal – to satisfy YOU, our customer! We are always striving to get better by developing new products, testing existing products or maintaining near perfect (99.9%) on-time shipments.

To put our team to work for you, give us a call!

And to all who may be distracted throughout these next four days – Good luck to your team as well!

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Basketball hoop image courtesy of Steve Johnson. Creative Commons License

EXAIR Nozzle Improves Safety & Worker Comfort

This week’s adventures in using compressed air arrives from an unexpected source: installing handlebar grips on a bicycle. The customer used a compressed air gun with an open tube which is not OSHA safe and is LOUD! (pictured below)

image3

This original nozzle does not comply with OSHA’s dead end pressure standard and is exceptionally loud.

The bicycle shop would slip the nozzle of the air gun under the rubber handlebar grips to expand them to slide onto the frames easily.  The original nozzle of the gun did not have a relief port in the nozzle to prevent pressurization over 30 PSIG as mandated by OSHA instruction STD 01-13-0001. On top of the over-pressurization problem, the gun was incredibly noisy. This noise was the reason for their call. During the course of our phone conversation, we also discussed the safety aspect of their application. If you need more information on OSHA’s regulation regarding compressed air please see my blog “Complying with OSHA’s Compressed Air Standard”.

image4

Customer slipping on a bicycle handlebar using a 1410SS Precision Safety Air Gun

The bicycle repair shop was relatively quiet, so the noise from the 0.175″ opening of the original safety air gun affected a number of shop employees. Every year more and more studies point to a link between occupational noise and health, well being, and productivity. This repair shop had a relatively low noise level in most working hours, so the noise of the air gun continuously rattling through rafters not only threatened the operators’ hearing but also may have affected them in other ways.  The technician manager of the repair shop had heard complaints from operators and called one of EXAIR’s Application Engineers to find a quieter solution. Our solution was the Precision Safety Air Gun, model 1410SS, was the perfect solution. The 1/4″ Nano Super Air Nozzle is 1/4″ in diameter which was able to easily slip underneath the handlebar grips. The gun would then be triggered which allow air to fill the handlebar grip, which caused it to expand just enough to slip onto the bike frame.

Originally, the air gun produced noise levels of over 90 dB every time the gun was triggered. EXAIR’s 1410SS Precision Safety Air Gun only produced a noise level of 75 dB, which is much more manageable in their shop environment. The gun also features EXAIR Super Air Nozzle design which conserves compressed air and complies with OSHA standard 1910.242(b), which prevents the outlet pressure from exceeding 30 PSIG.

Dave Woerner
Application Engineer
@EXAIR_DW
DaveWoerner@EXAIR.com

Super Air Wipe Blows Electric Resistance Welded Pipe Clean During Manufacture

SAW pipe

Super Air Wipe Blows Off Pipe

A manufacturer of Electric Resistance Welded (ERW) pipes contact us recently. They were trying to make improvements to an existing pipe mill where pipes of diameters 3-1/2” up to 8-5/8” diameter are being processed. They had previously used our Super Air Wipe product on a smaller line that produced pipe in the 2-3/8” to 3-1/2” outside diameter range with great success. So, they wanted to know what we had that could blow off the outside diameter of their large product.

It so happens that EXAIR produces the Super Air Wipe product up to 11 inch inside diameter. With such a size, the Super Air Wipe has capability to blow off and cool pipes up to about 10 inch diameter. This capability was well within the need for our customer.

Previously, the customer had been using a series of open pipes that terminated into a ring around their product to blow off coolant used during the final phases of production. This solution was extremely loud and used a large volume of air which ran continuously while the mill was in operation. Also, the finish produced was not quite as consistent as the customer wanted. The inconsistent velocity between the home made “nozzles” caused lines to form on the pipe’s outer surface finish that were not appealing.

The Super Air Wipe was able to harness the compressed air into a more manageable flow with even velocity all the way round the outside of the pipe. The sound level dropped considerably, the flow rate dropped down to a much more reasonable level for the customer and the visual quality of their final product had no lines as before.

The pipes produced at this particular facility were used in the oil and gas industry. However, any application where pipes, hoses, tubes and any other round forms need to be blown off or cooled with air create good opportunity to take advantage of the features that an EXAIR Super Air Wipe bring to the application.

Neal Raker, International Sales Manager
nealraker@exair.com

Video: How To Install A Cold Air Distribution Kit

The video below shows how to install an EXAIR Cabinet Cooler’s Cold Air Distribution Kit

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

All Kinds Of Useful Accessories…If I’d Only Known…

I’ve been learning an awful lot about car stereos lately. See, the LED display on the stereo in my wife’s car stopped working. It was intermittent for a while…I kinda knew deep down inside that it wasn’t going to fix itself…but it’s stopped working entirely now. So, we went out last weekend and got a great deal on an “open box” unit at a local Big Box Store. I’ve been back to The Store twice now, because…I’m embarrassed to admit…I didn’t do my homework on what all I needed up-front. I’ve spent almost as much on wiring harnesses, adapters, and hardware as I did on the stereo itself (which doesn’t bother me much…it was a RIDICULOUSLY good deal…maybe because it DIDN’T come with anything) and, three days later, I have everything I need to complete the installation. Which, since I have the wiring harnesses made up and all the plug-in adapters in hand, means I just have to plug in three connections, tighten four bolts, and snap the dashboard panel back in.

I tell you this, dear reader, as a cautionary tale…not just for car stereos, but for compressed air products. At EXAIR, we want to make it as easy as possible for users to get the most out of our products, so we offer a variety of very beneficial accessories:

Universal Air Knife Mounting Systems for our Air Knives.

Plumbing Kits for our Long Super Air Knives.

Stay Set Hoses and Swivel Fittings for our Super Air Nozzles.

A clip-on style Mounting Bracket for our Atomizing Spray Nozzles.

Chip Shields for our Safety Air Guns.

A broad assortment of Vacuum Cups, Fittings, Hoses, etc., for our E-Vac Vacuum Generators.

High quality Reinforced PVC Conveyance Hose for our Line Vac Air Operated Conveyors.

A variety of Suction Tools for our Industrial Vacuums.

Side Mount Kits for our Cabinet Cooler Systems.

And this doesn’t even include the products in our Accessories line – Filter Separators, Oil Removal Filters, Pressure Regulators…heck, we’ve even got accessories for our Accessories:

Again – EXAIR wants you to get the most out of our products. If you want to find out what else we might have to help you do just that, give me a call.

Russ Bowman
Application Engineer
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