Battling Heat Transfer

If you haven’t read many of my blogs then this may be a surprise. I like to use videos to embellish the typed word. I find this is an effective way and often gives better understanding when available.  Today’s discussion is nothing short of benefiting from a video.

We’ve shared before that there are three types of heat transfer, more if you go into sub-categories of each. These types are Convection,  Conduction, and Radiation. If you want a better understanding of those, feel free to check out Russ Bowman’s blog here.  Thanks to the US Navy’s nuclear power school, he is definitely one of the heat transfer experts at EXAIR.  If you are a visual learner like myself, check out the video below.

The Application Engineering team at EXAIR handles any call where customers may not understand what EXAIR product is best suited for their application. A good number of these applications revolve around cooling down a part, area, electrical cabinet, or preventing heat from entering those areas.  Understanding what type of heat transfer we are going to be combating is often helpful for us to best select an engineered solution for your needs.

Other variables that are helpful to know are:

Part / cabinet dimensions
Material of construction
External ambient temperature
If a cabinet, the internal air temperature
Maximum ambient temperature
Desired temperature
Amount of time available
Area to work with / installation area

Understanding several of these variables will often help us determine if we need to look more towards a spot cooler that is based on the vortex tube or if we can use the entrained ambient air to help mitigate the heat transfer you are seeing.

If you would like to discuss cooling your part, electrical cabinet, or processes, EXAIR is available. Or if you want help trying to determine the best product for your process contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Video Source: Heat Transfer: Crash Course Engineering #14, Aug 23, 2018 – via CrashCourse – Youtube – https://www.youtube.com/watch?v=YK7G6l_K6sA

Undersized Regulators Create Performance Problems with Compressed Air

“I have a Cabinet Cooler installed on my panel but it isn’t getting the temperature down cold enough. Can you quote me for a duplicate system to install on this panel?” This was a recent inquiry from a customer regarding an electrical enclosure that they had installed in their plant. The Cabinet Cooler was producing cold air, but not enough to keep the cabinet at their desired temperature. It would seem logical that they need additional capacity, right? While that could be the case, in this instance it most definitely was not.

When we get questions like this, we first want to take a closer look at the current installation. The cooling capacity for each system is published in our catalog. BUT, in order to rate a cooling capacity for any type of cooling system, some assumptions must be made. All Cabinet Coolers are specified with 70°F compressed air fed to the Cabinet Cooler at a pressure of 100 PSIG. In addition, each cooler has a specified volume of air that it must utilize in order to produce that rated cooling capacity. If any one of those parameters change, so does the overall cooling power.

In this particular case, the customer had installed a non-EXAIR pressure regulator just upstream of the cooler. Upon looking at the specifications for this regulator, it was found that the overall volume of air it can deliver was just 10% of the overall volume needed to produce the rated 1700 Btu/hr. They didn’t need another Cabinet Cooler System, they just needed to remove that restriction! Upon learning that it needed 100 PSIG, they removed the regulator and supplied full line pressure. No more heat alarms for that shift!

CC undersized valve

Rather than purchasing and installing an unnecessary system, they were able to get back up and running just by removing the problem upstream. At EXAIR, we want to make sure that you’re getting the most out of our products. Just because you call and inquire about a new purchase doesn’t necessarily mean that you need it. We’re here to help you determine if something is afoul with the current setup and make sure you have all of the knowledge necessary to rectify it.

We’re right in the middle of summer, and boy is it hot out there. If you have panels that are overheating and creating problems for you in your processes, give us a call. With Cabinet Cooler Systems ready to ship same day from stock (with properly sized regulators) you can have it fixed by tomorrow.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Calculating Heat Loads to Cool Electronic Cabinets

With the hot summer months upon us, elevated temperatures can cause shutdowns and interference with electrical systems.  For every 10 deg. C rise above the operational temperature, the life of an electrical component is cut in half.  With Freon-based coolers, higher ambient conditions make them less effective; and opening the electrical panel to have a fan blow inside creates a dangerous hazard as well as blowing hot, humid, dirty air inside the panel.  To reduce loss in production and premature equipment failures, it is important to keep the electrical mechanisms cool.  The EXAIR Cabinet Cooler Systems are designed to do just that.

To find the correct type and size, we need some information about your electrical panel.  EXAIR makes it easy with the Cabinet Cooler Sizing Guide.  This sheet goes over the important details to find heat loads, proper NEMA type, and options for easy installation. The EXAIR Cabinet Coolers range from 275 BTU/hr (69 Kcal/hr) to 5,600 BTU/hr (1,411 Kcal/hr) in cooling capacities.  And with the filled-out form, we can make sure that the correct model is recommended.  In this blog, I will cover a section of the sizing guide, the heat loads.

To properly cool, we need to calculate how much heat is being generated.  Heat loads come from three main areas; internal, external and solar.  Here are some methods to find the information needed for heat load calculations.

Internal Heat Load:  The internal load is the heat generated from inside the electrical panel.  This heat is produced from the inefficiencies of the electrical devices.  There are three ways that we can figure the internal heat load.

Step A: The simplest way is by hanging a piece of metal like a washer inside the panel for about 15 minutes.  We can get an average temperature inside.  The best place for the washer will be toward the top half of the panel, as heat rises.  In the sizing guide, you can mark the temperature next to “Internal temperature now”.

Step B:  if you know the electrical components inside that generate heat, a list can be made with volt/amp ratings, or watts.  This is very useful for new panels.  The major devices would be VFD (Variable Frequency Drives), power supplies, UPS, transformers, thyristors, etc.  We can calculate the inefficiency of the electrical components which will give us the internal heat load.

Step C:  If you know the amount of power going into the panel, and the amount of power leaving the panel, the difference will tell us the amount of power that remains for the electrical components.  We can take a 5% average as the heat loss.

External Heat Load:  The external heat load is attributed to the environment surrounding the electrical panels.  This is a standard temperature reading in oF or oC.  Only with Step A above, we will need to know the external temperature at the time that you measured the internal heat measurement.  This needs to be placed in “External Temperature Now”.  The difference to the internal temperature will give us the heat load per square feet (square meter).  Reference chart below.  We will also need to know the highest external temperature that the panel will see.  So, during the hottest day of the hottest month, the EXAIR Cabinet Cooler will still be able to keep your electronics cool and operational.

Solar Heat Load:  The solar heat is only needed if the panel is located outside without cover and exposed to sunlight.  For this type of heat load, we will need to know the color of the electrical panel.  Lighter colors will not absorb as much heat as darker colors.

Because there is so much information that is critical for proper sizing, the Cabinet Cooler Sizing Guide is the best tool to use to facilitate the calculations.  I gave examples above to find different ways to get the proper information.  Electrical shutdowns are expensive and annoying.  If you have interruptions from high internal temperatures, EXAIR Cabinet Coolers are a great solution.  They can be installed quickly and easily.  With no moving parts or costly preventative maintenance needed, they can run for decades in keeping your electronics cool.  For our U.S. and Canadian customers, you will receive an AC Sensor for free, a $58.00 value, as a promotional item from now until the end of August 2020 with qualified purchases.  How can you not give them a try?  If you have any questions about Cabinet Coolers or the Sizing Guide, you can contact an Application Engineer at EXAIR.  We will be happy to help.

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

Cabinet Coolers Material Selection Focus: 316 Stainless Steel

Industrial environments call for equipment to be constructed of many different materials in order to stand the test of time and to meet standards set by governing agencies. Within certain environments, 316 stainless steel rules the world and there is due cause for it. In given areas, there may be chemical incompatibilities, temperature limits, or even material incompatibilities between parts within a process and the process itself.  This is why the EXAIR Cabinet Cooler Systems are available in 316 stainless steel.

The NEMA Type 4X Cabinet Cooler Systems are standard in 303 stainless steel while 316 stainless steel is also available from stock and can meet or exceed the standards set forth by NEMA Type 4X environments to stand the test of time whether it be chemical/caustic washdowns that generate the need, product material compatibility, or due to being outside.  These systems are offered in both thermostatically controlled with choice of 120 VAC, 230 VAC, or 24 VDC solenoid valve or continuous operation and can all ship same-day on orders received by 3 PM ET for domestic orders.

We also offer Hazardous Location NEMA Type 4X Cabinet Cooler Systems in both 303 and 316 stainless steel to cover even more stringent classified areas that demand UL Classified certifications.   These meet certifications for Class I Div 1, Groups A, B, C and D, Class II Div 1, Groups E, F and G, as well as all Class III environments.  These systems are also offered in the same thermostat control voltages as well as a continuous operation.

The point is, if you have an overheating control panel or electrical panel, we will have a solution that can keep your production running, all you have to do is contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF