Fundamental Modes of Heat Transfer

Generally I like to write about cool stuff. Whether it is a new product like our TurboBlast Safety Air Gun, an application that really helped cool down a process for a customer, or even something cool I have done like a GORUCK event or training. Well, today is not one of those days, today we are going to talk about the opposite of cool … HEAT and more importantly the methods it is transferred.

1 – Energy Transfer – Heat

The process of how heat is generated all starts with a conversion of energy. Whether it is friction, or converting energy to light, or even converting energy to a different voltage through something like a transformer. No matter how it is generated, heat will begin to transfer. On the molecular level, atoms are storing the energy which will cause electrons to enter into an excited state and rapidly switch between shells. When the electron returns back to a lower shell (closer to the nucleus) energy is released; the energy released is then absorbed by atoms at a lower energy state and will continue until the thermal energy is equal between the two objects. Heat has four fundamental modes of transferring energy from surface to surface and they are as follows:

Conduction
Conduction can also be referred to as diffusion and is the transfer of energy between two objects that have made physical contact. When the two objects come into contact with each other thermal energy will flow from the object with the higher temp to the object with the lower temp. A good example of this is placing ice in a glass of water. The temperature is much lower than the room temperature therefore the thermal energy will flow from the water to the ice.

Radiation
Radiation is the transfer of thermal energy through empty space and does require a material between the two objects. Going back to the how thermal energy is released from atoms; when the electron returns to a lower energy shell the energy is released in the form of light ranging from infrared light to UV light. Energy in the form of light can then be absorbed by an object in the form of heat. Everyone experiences radiation transfer every day when you walk outside; the light from the sun’s radiation is what keeps this planet habitable.

Convection
Convection is the transfer of thermal energy between an object and a fluid in motion. The faster the fluid moves the faster heat is transferred. This relies on the specific heat property of a molecule in order to determine the rate at which heat will be transferred. The low the specific heat of a molecule the faster and more volume of the fluid will need to move in order to get full affect of convection. Convection is used in modern ovens in order to get a more even heat through out the food while cooking.

Advection
Advection is the physical transport of a fluid from point A to point B, which includes all internal thermal energy stored inside. Advection can be seen as one of the simpler ways of heat transfer.

No matter how the heat is transferred to an object, if it needs to be cooled there is a good chance that one of our Application Engineers has approached a similar issue and can help. To discuss, contact us and we will walk through the best method to eliminate the heat you need to.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – “Energy Transfer – Heat” by Siyavula Education is licensed under CC BY 2.0

Find It, Tag It, Fix It: Addressing Parasitic Draw

Leeks, and not the compressed air kind!

Leaks, and not the kind you see on a cooking show, are never good. Before you comment, yes I know the vegetable is spelled leek, that’s just the strength of my dad jokes. The point of this post is actually discussing leaks, mainly of the compressed air variety. All leaks cost. I recently found a leak within my home which was accounting for around a 20% increase in my water bill. Sad to say that it took a few months to locate, and solve the issue. Over the years, I’ve seen many facilities deal with common leak problems like being unable to leave their compressed air pipes energized over night because the parasitic draw will drain the entire system. That’s a problem!

Burst pipes and leaks are ALWAYS costly!

If the leaks are present when nothing is being utilized, then that means parasitic draw is happening on the system. This is when energy that is being converted into compressed air isn’t used but instead, leaking out to atmospheric conditions. These parasitic draws are not always easy to locate, so over the years I’ve had to help a few customers address this problem. One in particular stands out, so I am going to share how we honed in on the leak and ultimately gave them days without a shutdown.

The conversation all started with a customer asking about how our Digital Flowmeters work, and if they could be used to determine which production line is using the most air, and more importantly why their production line shuts down for low air pressure. After I explained how we would select their infeed pipe size as well as size a meter that would fit each machine infeed, we got to talking about the shut down sequence.

The approach they took to solving the issue was to first capture the flowrate of the entire system and then to evaluate the flowrates of each segment of their plant. From there, we would install flowmeters on the higher usage sectors, and drill down to each machine for the finite analysis. They could then go through all the other production lines and generate a full facility consumption profile. To start, they found one packaging line that was using a considerably higher volume of air throughout their first shift than any other line and than any other shift.

Once they started breaking down the high demand production line they found one leg of the production line which had a spike in usage at the same time every day. The trick was they couldn’t find a machine with high usage, that is until they traced all of the piping and found a filter bag house on the roof that had been added to the line at some point. This wasn’t documented and had a piece of pipe that had failed causing an open dump during the cleaning cycle every day at 2:30 in the afternoon.

This was all made possible by setting up multiple flowmeters with wireless capabilities so they could document and compare the usages between machines and production lines ultimately giving them a considerable amount of production time back into the day by fixing a broken pipe that caused daily shutdowns.

If you would like to discuss how to layout a compressed air monitoring system in your facility or the best way to track down the cause of some leaks and high compressed air demand, contact an Application Engineer.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – Leeks on shelf – Jeffery Martin, CC0, via Wikimedia Commons – retrieved from – https://commons.wikimedia.org/wiki/user:Veronicasgardentracker

About OSHA 29 CFR 1910.242(b) for Compressed Air Safety

In February of 1972 OSHA released a standard to improve worker safety when operating handheld compressed air devices being used for cleaning purposes. This directive focuses around human skins permeability. That is, if you were to take an open ended pipe that had compressed air being discharged over 30 psig it can actually push through the skin and create an air embolism.

OSHA’s Directive 29 CFR 1910.242(b)

Air Embolisms are extremely painful, and in extreme cases, can be deadly. The risk associated with an air embolism can be mitigated by following the OSHA directive and reducing the downstream pressure of an air nozzle or nozzle pressure below 30 psi for all static conditions. Dead ending is when the passageway for the air becomes blocked and turns a dynamic flow of air into a static flow. This is in the event the pipe, nozzle, lance, etc. becomes blocked by a human’s body. This is a directive that all Intelligent Compressed Air® products from EXAIR focus on meeting or exceeding.

Our Air Nozzles and Jets video shows a great depiction of how this can be achieved with our engineered design of nozzles. The recessed holes and the fact that there are multiple passages for the air to exit are easy to see on the nozzle. Products like the Super Air Knife may not be so easy to see but the way the air knife cap overlaps prevents the Super Air Knife from being dead ended in the event an operator comes into contact with the discharge air.

Even though this directive was created in 1972 it continues to be at the forefront of industrial environments. I have even been to a custom artwork facility that was effected by this standard because they would use a handheld blowgun to remove dust and debris before matting and framing artwork with glass. They also removed dirt and dust from the frames before paint. This wasn’t your typical manufacturing environment yet they were still held to the same standards and were made safe by implementing engineered solutions such as our Super Air Nozzle.

If you would like to discuss how we can help increase your operator safety and ensure you meet or exceed OSHA 29 CFR 1910.242(b), please contact an Application Engineer today.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – OSHA Instruction STD 01-13-001 – Retrieved from: https://www.osha.gov/enforcement/directives/std-01-13-001

Overheating Cabinets Are Bad. Cabinet Cooler Systems on Promotion Are Good!

In southwest Ohio we are currently experiencing 88°F. And we have begun to see increased numbers of inquiries for Cabinet Cooler Systems to keep control cabinets cool. This comes with the territory of approaching summer here in the northern hemisphere, and elsewhere it is due to new machines going into areas of a facility where it is constantly hot and dirty. It seems like the perfect time to offer up some free stuff with our Cabinet Cooler Promotion.

That’s right, order any of the Cabinet Cooler® Systems listed and receive a free A/C Sensor Pen. This pen has saved me from getting shocked many of times around my home.   Without it of course, I find myself guessing I turned the correct breaker off and, as soon as I touch the outlet I am working on I get hit with 110V. This sensor is helpful to locate the presence of voltage and avoid getting shocked.

We are here to assist your choice of Cabinet Cooler system and to provide a very fast solution to the downtime you are experiencing. We manufacture Cabinet Cooler systems from 275 Btu/Hr through 5600 Btu/Hr with NEMA 12, 4 and 4X integrity as well as Hazardous Location. If you don’t know what Cabinet Cooler System you need, take a look at our new Cabinet Cooler Calculator or the form below. It can be found on our site, get the information and call, fax, e-mail or live chat with an Application Engineer to get a quick and accurate response on what amount of cooling your system will need.

Sizing Guide

Over our thirty years in business we have also seen many companies who only experience a short span of seasonal heat and have found that 2000 Btu/Hr is enough refrigeration to offset summertime heat load, in most cases. Choosing a model with a thermostat control will turn the cooler on and off as needed and minimize compressed air use. Cabinet Cooler systems are in STOCK and ship same day for domestic and Canadian orders received by 3:00 pm EDT. We can get your cabinet cooled FAST and eliminate your heat related problems. Cabinet Cooler systems are shipped ready to install through a standard electrical knockout. There is no waiting for oil to settle back into the compressor motor, no mounting templates required or huge holes to cut into your cabinet. Cabinet Cooler systems have no moving parts to wear, making them rugged and lasting in your hot environment.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF