Cooling-system longevity often governed by heat-transfer fluid choice

May 1, 2015

Reliable systems keep maintenance to a minimum and output to plan.

By Dr. Phil Gray

Automobiles don’t need constant maintenance the way they did, say, 30 years ago, and the same expectation is found today in industry. Reliable systems keep maintenance to a minimum and output to plan.

In this regard, choosing cooling systems in the food & beverage industry is governed by several factors.

For one, any heat-transfer fluid used within a system must have low toxicity, and ensure product as well as process-plant employee and customer safety. Productivity-wise, poor-quality heat-transfer fluids cause regular maintenance, leaks and even system failures.

Micro-brewery Lindesnes Brygghus was established in Lindesnes, Norway in 2011, selling beers golden, dark and bitter, at more than one hundred locations. Brewery production and storage is all about temperature control and a brewery needs effective and reliable cooling and refrigeration to ensure product safety and longevity. Heat transfer fluids are a vital part of these systems.

As a market newcomer, Lindesnes Brygghus needed confidence it could supply on time and at capacity, while ensuring quality and value against overhead. They required a cooling system that would last and pay return on investment.

Again, in this regard, when it comes to heat-transfer fluids, glycol-based fluids are not particularly corrosive in concentrate form. But once mixed with water, corrosion, bacterial growth and scaling can become an issue. The cooling system’s life span is directly dependent on fluid quality.

On the other hand, using an inhibited glycol mixed with water of sufficient quality can improve the reliability and effectiveness of systems.

Behind the beer

Lindesnes Brygghus engaged with Energy Rent AS, specializing in refrigeration and process cooling, to find its cooling system, and the heat-transfer fluid that would be used with it.

Kilfrost Cooltrans SustainCTS fluid is a 1,3-propylene glycol-based concentrate fluid (Bio-PDO) manufactured from corn-sugar, a more "sustainable" choice than petroleum-derived 1,2-propanediol (mono propylene glycol). As the heat transfer fluid is used in an indirect cooling process, with potential risk of contact with beverages, it is important that the fluid is non-toxic, non-hazardous and free from carcinogenic, mutagenic and reprotoxic (CMR) additives.

Bio-PDOTM-based heat-transfer fluids offer specific performance advantages over petroleum-derived propylene glycol-based transfer fluid. With the same level of freeze protection, viscosity is 33 percent lower viscosity at -20 degrees C, which means an improved low-temperature viscosity profile that translates into improved hydraulic performance and lower system pressure drops.

For example, a 40 percent v/v solution (solute concentration expressed in volume/volume percent) of mono-propylene glycol-based fluid requires up to 2.4 times more pumping energy than a 40 per cent v/v solution of Cooltrans SustainCTS at -10 degrees C.

Besides improved low-temperature hydraulics, an inhibited glycol also provides significant higher thermal stability, being up to four times more resistant to oxidative degradation than standard propylene glycol-based fluid.

"The impact poor-quality fluids have on cooling systems shouldn’t be underestimated," says Morten Magnusson, managing director, Energy Rent. "To give customers confidence in our systems, high-quality fluids are specified."

Specs and standards

An international standard created by the American Society for Testing and Materials, or ASTM International, for corrosion testing, known as the ASTM D1384-05, gives a good indication of the corrosion protection and resistance to degradation that a heat transfer fluid offers.

A heat transfer fluid that meets ASTM-D1384-05 corrosion-test standards maximizes equipment longevity and minimizes otherwise unnecessary shutdowns and repairs.

Use of glycol in manufacture of heat transfer fluids will help minimize carbon footprint and greenhouse gas emissions in industries using cooling systems, including food & beverage, pharmaceuticals and just about any industry where commercial heating & cooling takes place.

The manufacture of corn sugar-derived glycol (bio-PDO) uses up to 40 per cent less energy when compared to standard propylene glycol. Further reductions are also possible due to the performance advantages that the bio-PDO offers as a heat-transfer fluid in the end application.

Using poor-quality heat-transfer fluids is problematic. Mix good quality water with inhibited glycol, for greater reliability and effectiveness.

Dr. Phil Gray is specialty fluids technical manager at Kilfrost’s Specialty Fluid Division.

With U.S. headquarters in Boca Raton, Florida, Kilfrost is a market leader in de-icing and anti-icing products for the aviation and transportation industries. Its Specialty Fluids Div. produces heat-transfer and industrial fluids.

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