Welding Chillers and Heat Management

Welding Chillers and Heat Management During Welding

6/13/2018

Welding is a common procedure used to join two or more pieces of metal for use in a wide range of applications. The process can be done at outdoor locations (e.g. farms, highways, construction sites) or in an indoor setting, typically shops and factories.

PHOTO CREDIT: Adam Harris Company Healthyhandyman.com [email protected]

Welding requires the following components: metals to be joined, a heat source, and a filler metal. The most common types of welding found in industrial environments are: Gas Tungsten Arc Welding (GTAW), Stick Welding, Gas Metal Arc Welding (GMAW), and Flux Core Arc Welding. [read: 4 Popular Types of Welding Procedures]

It may go without saying, but high-quality welding requires careful heating/temperature management. Temperature management before, during and after welding defines the preciseness and quality of the weld.

Here are a few reasons why we’re careful about temperature control when it comes to welding:
It can prevent some costly and time-consuming reworksWhen working on common materials like cast irons, copper (and its alloys) aluminum, and steels, proper heat dispersion and management prevents stress and weakened metals. Quick changes in temperature can mean extra work if not wasted materials. Take it from us: any time saved by cutting corners on heat control will only come back to haunt you. It’s better to take your time with temperature to maintain the integrity of your materials and product.

It reduces the risk of Hydrogen Induced Cracking (HIC)Hydrogen Induced cracking, is “caused by the blistering of a metal due to a high concentration of hydrogen.” Carefully approaching the heating and cooling of welded materials allows hydrogen to be properly drawn out. This effectively reduces or eliminates the risk of HIC and, consequently, expensive and time-consuming reworks (see above).

It relieves residual stress(THE SILVER BRIDGE IN OHIO, 1967, BELIEVED TO HAVE COLLAPSED DUE TO RESIDUAL STRESS FROM UNEVEN COOLING)

In welding, the quick thermal expansion and reduction created along a very limited spot could become a major source of residual stress. This is stress that remains within an object/material after the external source of stress has been removed. While residual stress may be desirable in some engineering applications, uncontrolled residual stress should be avoided at all costs. This uncontrolled, undesirable stress leads to weak welds and premature structural failure.

Residual stress frequently occurs when a welded metal’s temperatures are raised and quickly lowered with little or no control or when cooling occurs unevenly. Slowly and carefully removing heat from welded materials prevents the welded spot from becoming too fragile and ductile.

At North Slope Chillers, we’re all about taking the stress out of welding temperature control (pun intended). Our products provide controlled, even cooling that will help maintain the strength and integrity of your welded products. Additionally, we offer custom solutions– whatever your cooling needs are, we can help!
Give us a call at (866) 826-2993 if you’re interested in incorporating a chiller into your welding process.

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Determining Chiller Size

3/27/2018

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We cannot overstate the importance of selecting a correctly sized chiller. Undersized chillers won’t correctly cool your process equipment or materials. Oversized chillers will work just fine, but why pay more than you need to? When you select a chiller of the proper size, you can rely on several years of efficient cooling. Use the formula below to determine the chiller size that will most optimally meet your needs.

The Formula
Regardless of what you are cooling, this formula will determine your needed chiller size. Before jumping in, identify the following variables:

Incoming water temperature
Required chilled water temperature
Flow rate

To illustrate how this formula works, let’s say we need to cool 4 GPM (gallons per minute) from 85 °F to 75 °F. This makes our incoming water temperature 85 °F, the required chilled water temperature 75 °F and the flow rate 4 GPM.

Step One: Calculate Temperature Differential (ΔT°F)ΔT°F = Incoming Water Temperature (°F) – Required Chilled Water Temperature.
Example: ΔT°F = 85°F – 75°F = 10°F

Step Two: Calculate BTU/hr.BTU/hr. = Gallons per hr x 8.33 x ΔT°F
Example: (4 gpm x 60) x 8.33 x 10°F = 19,992 BTU/hr

Step Three: Calculate tons of cooling capacityTons = BTU/hr. ÷ 12,000
Example: 19,992 BTU/hr. ÷ 12,000 = 1.666 tons

Step Four: Oversize the chiller by 20%Ideal Size in Tons = Tons x 1.2
Example: 1.666 x 1.2 = 1.9992

Most likely, your “Ideal Size in Tons” is not going to come out to an even 1 ton, 5 tons, 20 tons, etc. Round up to determine which chiller size you will need. In this example, our final answer is 1.9992, which means we will need a 2-ton chiller.

We hope this was helpful! Of course, if you have any questions or would like us to size your chiller for you, please give us a call at (866) 826-2993.

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How Chiller Systems Work

12/20/2017

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If you work with industrial machinery, you might use a chiller system to keep your machines from overheating. They can be very effective in keeping things at optimal temperatures, but how does a chiller work? Knowing how a chiller works can be helpful in choosing the best system to meet your needs.

How a Chiller Works
To put it simply, industrial chillers cool process fluids. Process fluids (typically water or a water/glycol mix) are used to cool machinery, equipment, food, etc. The process fluid absorbs heat from what is being cooled and then goes through the chiller where the heat is removed from the process fluid and transferred to the ambient air.

Two Circuits
Chiller systems contain two main circuits: a refrigeration circuit and a fluid circuit. The refrigeration circuit is made up of four components: the compressor, the condenser, the expansion valve and the evaporator. The refrigeration circuit removes heat from the process fluid. The fluid circuit is typically comprised of a process fluid reservoir, a pump, filters, and a heat exchanger. The fluid circuit carries the process fluid around the object being cooled.

The Refrigeration Cycle Step by Step – Chiller Diagram

The refrigeration circuit is the most technical part of how a chiller works.The refrigeration cycle uses the principles of thermodynamics to efficiently move heat from one area to another. In the case of chillers, heat is taken from the fluid being chilled and transferred to the ambient air.

1. The Compressor
The refrigeration cycle begins with the compressor. The compressor takes low-pressure low-temperature refrigerant in gas form and compresses it into a high-pressure high-temperature gas.

2. The Condenser
This gas then flows through coils in the condenser. While in the condenser, air or water will flow over the coils and remove heat from the refrigerant. As the refrigerant loses heat it will begin to condense until all of the gas has condensed into a liquid.

3. The Expansion Valve
After leaving the condenser, the liquid goes through the expansion valve. The expansion valve restricts the flow of refrigerant. When the high-pressure liquid goes through the expansion valve it enters the evaporator.

4. The Evaporator
The evaporator is where the refrigerant starts evaporating back into a gas. When the refrigerant evaporates it gets very cold and absorbs a lot of heat. It is in the evaporator that the process fluid will interact with the cold refrigerant. Heat is removed from the fluid and transferred to the refrigerant. The refrigerant will then enter the compressor and the cycle begins again.

North Slope Chillers

Now that you know how a chiller works, you may be considering your chiller system options. North Slope Chillers boast the most advanced active refrigeration circuit available. They are easy to install, remove and relocate and will not disrupt the layout of your current system. Whether you’re looking to cool, freeze, or anything in between, North Slope offers a solution to meet your needs.

Additional resources
https://www.thermalcare.com/how-does-a-chiller-work/
https://en.wikipedia.org/wiki/Chiller

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