Rudolf Hilsch helped to advance vortex tube technology into what it is today.
If you look into the history or even the definition of a vortex tube, you’re likely to find mention of a physicist named Rudolf Hilsch. Born December 18th, 1903, Hilsch was a German physicist, professor, and manager of the Physics Institute of the George August University of Göttingen. He received a doctorate degree by the age of 24 and spent his career furthering the advancement and understanding of numerous phenomena of physics.
Although Hilsch didn’t invent the Vortex Tube (the original inventor was a physicist by the name of Georges J. Ranque), he is entwined with their history thanks to a paper he published in 1947. According to lore, this paper significantly changed the understanding and performance capabilities of the vortex tube, eventually being marked as the precursor for identifying a vortex tube as a real potential cooling device. (I’ve made attempts to find this 1947 publication properly translated into English, but to no avail. If you have it or find it, please email it to me at LeeEvans@EXAIR.com! (Original publication in German can be found here.)
Given that vortex tubes are a known EXAIR solution, it seems reasonable that today, on Hilsch’s birthday, we give recognition to this influential physicist and his mark on thermodynamic fluid flow technology. And, although we at EXAIR are connected to Hilsch through vortex tubes, everyone alive has been influenced by his work. This is because Hilsch and a partner (physicist Robert Wichard Pohl) constructed the first semiconductor amplifier in 1938, prompting Hilsch to prove (in 1939) that solid-state electronics are possible. This work paved the way for transistor and solid-state electronics technology as we know it today. Without Hilsch and his life’s work, not only would we not have vortex tubes, we likely would have any electronic devices we use every day.
Here’s to you Rudolf Hilsch. Thank you for your work, your discoveries, and your achievements.
An electrical enclosure in need of a reliable cooling solution.
On first glance, the enclosure shown above looks to be fairly large for use with an EXAIR Cabinet Cooler. Our individual Cabinet Coolers have a maximum cooling capacity of 2,800 BTU/hr. (~820W), but we do provide dual Cabinet Cooler systems with capacities up to 5,600 BTU/hr. (~1642W). So, although there are heat loads which are too large for use with an EXAIR Cabinet Cooler, we always perform heat load calculations for any potential application because until you run the numbers, you don’t really know.
Arrows identifying existing A/C unit
In this case, however, the customer already knew the required cooling capacity (~3,000 BTU/hr. or 880W) thanks to an existing refrigerant based system already installed (see arrows above). This existing system was doing a great job of keeping the enclosure cool when it was working properly, but it was also prone to maintenance and breakdowns. The facility maintenance technicians had replaced filters as required on their preventative maintenance programs, but the A/C unit still required replacement multiple times. This would lead the maintenance team to open all the doors of the enclosure in an effort to remove heat, but this allowed dust and dirt to enter the cabinet and compromise the electronics inside.
Eventually, the maintenance, required repair, and exposure of sensitive electronics led this customer to search for an alternative solution, and they found the EXAIR Cabinet Cooler. Once we determined the required cooling capacity and a suitable unit (model 4750 NEMA 4 Dual Cabinet Cooler System with 3,400 BTU/hr. (~1,000W) of cooling power), the discussion turned to installation and maintenance and we had a conversation something like this:
Customer: How much time do we need to hook up the Cabinet Cooler?
Customer: Ok, what about PM (preventative maintenance)?
EXAIR: There isn’t any. Just feed it with clean, filtered compressed air and it will run for years.
Customer: Ok, how do we turn it on and off?
EXAIR: Well, you don’t have to. You just install the thermostat and the system does the rest. It’ll maintain whatever temperature setpoint you chose and comes preset to 95°F (35°C).
Customer: What is the lead time?
EXAIR: They’re in stock and ship same day.
After working through the application and questions from the customer, we were able to provide a sustainable, readily available solution that was a marked improvement from the maintenance prone refrigerant based system. Our Cabinet Cooler allows for easy installation, no maintenance, and years of trouble-free operation. If you have an overheating enclosure contact an EXAIR Application Engineer. We’ll be happy to help you find a suitable solution.
In the world of compressed air blow off solutions, there are a number of options which customers must consider. Should the plant maintenance personnel configure something on-site? Is there a low-cost option available from a catalog warehouse? Or, is there an engineered solution available – and if there is, what does this even mean?
Blowoff comparison
Ultimately, the exercise in comparing these options will help select the option best for the application and best for the company. In order to make these comparisons, we will consider each option based on the following attributes: Force, sound level, safety, efficiency, repeatability, and cost. These are the factors which impact the ability to perform as needed in the application, and effect the bottom line of the company
Force
How much force do you need in your application?
Blow off applications require a certain amount of force in order to perform the desired task. If the blow off is in a bottling line, for example, we will aim for a lesser force than if blowing off an engine block. But, no matter the application need, we will want to consider the ability of the solution to provide a high force, high impact blow off. Homemade and commercially mass-produced nozzles produce low-to-mid level forces, which translates to a need for more compressed air to complete a task. Engineered nozzles produce high forces, minimizing compressed air use.
Sound level
Have you ever been to a concert and felt your hearing reduced when you left? This can be the case for personnel in industrial environments with unregulated noise levels. Homemade or non-engineered blow off solutions carry the risk of increased sound levels which are outside of the acceptable noise level limits. EXAIR engineered nozzles, however, are designed to minimize sound level for quiet operation and continual use.
Safety
All EXAIR products meet or exceed OSHA Standard 29 CFR 1910.242(b)
Workplace safety is a serious matter for everyone from shop floor personnel to executive management. Whether you’re working with or near a compressed air operated device, or your making decisions for your company which have to do with the compressed air system, safety is undoubtedly a priority. Unfortunately, homemade and commercially available nozzles normally fail to meet OSHA standards for dead-end pressure requirements (OSHA Standard 29 CFR 1910.242(b)). This means that these solutions can pose a risk of forcing compressed air through the skin, resulting in an embolism which can cause severe harm or even death.
EXAIR nozzles, however, are designed to NEVER exceed dead-end pressure limits and to provide an escape path for airflow in the even the nozzle is blocked. This safety aspect is inherent in ALL EXAIR designs, thereby adding safety to an application when an EXAIR product is installed.
Efficiency
EXAIR Super Air Nozzle entrainment
Compressed air is the most expensive utility in any facility. Energy enters as an electrical source and is converted into compressed air through a compressor where up to 2/3 of this energy is lost as heat. The resulting 1/3 of converted energy is then piped throughout a facility as compressed air, where up to 1/3 of the air is lost to leaks. With this in mind, maximizing the efficiency of a nozzle solution becomes imperative. A homemade solution or commercial nozzle does not maximize the use of the compressed air. The result is a need to increase flow or increase pressure, both of which result in higher energy costs.
EXAIR nozzles are designed for maximum force per CFM. This means that any of our nozzles will produce the highest force at the lowest possible compressed air consumption. This, in turn, reduces demand on the compressed air system and allows for a lower energy requirement. Less energy demand means less energy costs, which goes straight to the bottom line of your company.
Repeatability
The EXAIR family of nozzles
When installing a nozzle solution, it is important to have the same force and flow from each unit. If a solution needs to be replicated, balanced, or adjusted in any way, having various forces and flows from a homemade setup will induce difficulty and could make changes impossible. Line speed or volume increases may not be possible due to variance in the output flow and forces from homemade setups, but an engineered solution will produce the same output every time. This means you can adjust the nozzles as needed to achieve the perfect solution in your application.
Cost
For many customers and businesses, the most important aspect of any solution comes down to cost. Will the solution work? And, how much does it cost? When it comes to a homemade or commercial blow off solution, it may or may not work, and it will have a low purchase cost. But, the purchase price isn’t the whole story when working with compressed air. The real cost of an item is in the operation and use. So, while a homemade solution will be cheap to make and install, it will be EXPOENTIALLY more expensive to operate when compared to an engineered solution. An excellent example is shown above. An open copper tube is compared to an EXAIR model 1102 Mini Super Air Nozzle. The copper tube cost only a few dollars to install, many times less than the EXAIR nozzle, but it costs almost two THOUSAND dollars more to operate in a year. Translation: Install a cheap blow off solution and pay for it in utility costs.
EXAIR nozzles and blow off solutions are engineered for maximum force, lowest possible noise level, OSHA safety compliance, maximum efficiency, and maximum repeatability. These factors allow for options which not only solve application problems, but also do so with the lowest total cost possible. If you have an application in need of a blow off solution, feel free to contact our Application Engineers. We’ll be happy to help. And, if your curious about the benefit of our products in your application, consider our Efficiency Lab. We will test your existing setup next to our recommended EXAIR solution and provide the impact to your bottom line.
A receiver tank is a form of dry compressed air storage in a compressed air system. Normally installed after drying and filtration, and before end use devices, receiver tanks help to store compressed air. The compressed air is created by the supply side, stored by the receiver tank, and released as needed to the demand side of the system.
But how does this work?
The principle behind this concept is rooted in pressure differentials. Just as we increase pressure when reducing volume of a gas, we can increase volume when reducing pressure. So, if we have a given volume of compressed air at a certain pressure (P1), we will have a different volume of compressed air when converting this same air to a different pressure (P2).
This is the idea behind a receiver tank. We store the compressed air at a higher pressure than what is needed by the system, creating a favorable pressure differential to release compressed air when it is needed. And, in order to properly use a receiver tank, we must be able to properly calculate the required size/volume of the tank. To do so, we must familiarize ourselves with the receiver tank capacity formula.
An EXAIR 60 gallon receiver tank
Receiver tank capacity formula
V = ( T(C-Cap)(Pa)/(P1-P2) )
Where,
V = Volume of receiver tank in cubic feet
T = Time interval in minutes during which compressed air demand will occur
C = Air requirement of demand in cubic feet per minute
Cap = Compressor capacity in cubic feet per minute
Pa = Absolute atmospheric pressure, given in PSIA
P1 = Initial tank pressure (Compressor discharge pressure)
P2 = minimum tank pressure (Pressure required at output of tank to operate compressed air devices)
An example:
Let’s consider an application with an intermittent demand spike of 50 SCFM of compressed air at 80 PSIG. The system is operating from a 10HP compressor which produces 40 SCFM at 110 PSIG, and the compressed air devices need to operate for (5) minutes at this volume.
We can use a receiver tank and the pressure differential between the output of the compressor and the demand of the system to create a reservoir of compressed air. This stored air will release into the system to maintain pressure while demand is high and rebuild when the excess demand is gone.
In this application, the values are as follows:
V = ?
T = 5 minutes
C = 50 CFM
Cap = 40 SCFM
Pa = 14.5 PSI
P1 = 110 PSIG
P2 = 80 PSIG
Running these numbers out we end up with:
This means we will need a receiver tank with a volume of 24.2 ft.³ (24.2 cubic feet equates to approximately 180 gallons – most receiver tanks have capacities rated in gallons) to store the required volume of compressed air needed in this system. Doing so will result in a constant supply of 80 PSIG, even at a demand volume which exceeds the ability of the compressor. By installing a properly sized receiver tank with proper pressure differential, the reliability of the system can be improved.
This improvement in system reliability translates to a more repeatable result from the compressed air driven devices connected to the system. If you have questions about improving the reliability of your compressed air system, exactly how it can be improved, or what an engineered solution could provide, contact an EXAIR Application Engineer. We’re here to help.
