Market research suggests the global heat transfer fluids market size was 465.9 kilo tons in 2014 and projects significant increases up to 2022. Dr Chris I Wright examines how the sampling of a heat transfer fluid (HTF) may help to maintain an efficient pump and thermal plant.

Chris Wright is a research scientist whose research focuses on the use and maintenance of heat transfer fluids in manufacturing and processing, which includes food, pharmaceutical, specialist chemicals and solar sectors. (Image: Global Heat Transfer Ltd.)

Many chemicals are used in the manufacture of HTFs and include silicone, aromatic, mineral and glycol. The speed that they are pumped around a thermal plant is affected by a number of factors including the speed of the pump and also the characteristics of the fluid itself. This includes the build-up of carbon (which increases kinematic viscosity) through the thermal degradation of the fluid over time (i.e., ageing) as well as the overall cleanliness of the fluid as a result of ongoing plant operation.

 
The natural ageing of the fluid can lead to the fluid thickening and this requires more energy to pump the fluid and as a result the efficiency of the plant will decrease as more energy is required to achieve the same output. This can also increase the risk of increased stress being placed on the pump and the need for the repair or replacement of its operating parts.
 
One of the easiest ways to manage the condition of a fluid is through routine sampling of the fluid as this is an indirect method for assessing directly the condition of the fluid and indirectly the plant. Indeed, as a fluid degrades it will form more carbon and become more viscous, and these changes can be detected in the sample of fluid taken from the plant.
 
Table 1. The effect of fluid ageing on plant efficiency.
 
 
Natural ageing of the fluida
Routine sampling of the fluid
Result
↑ energy to pump fluid
→ energy to pump fluid
↓ efficiency of plant
→ efficiency of plant
↑ risk of pump wear and the need for repair or replacement
→ risk of pump wear and the need for repair or replacement
a, this can include increased carbon in the fluid and/or increased kinematic viscosity.
 
In summary, the cost of routinely sampling a fluid represents an additional cost, but is a simple and effective way to avoid the longer-term detrimental effects that result from the natural degradation of fluid as it operates continuously at a high temperature over time.
 
Sampling does, however, work to keep the energy consumption of a pump constant and thus sustains the efficiency of the overall thermal plant. Another advantage from sampling a fluid is that changes in condition can be detected early and the cost of replacing component parts of a pump may be avoided. Options used to manage carbon build-up in a HTF have been discussed in a previous article  and include reductions in the operating temperature, dilution of the fluid, installation of temporary or a permanent filtration unit, the complete replacement of the HTF and reductions in the acidity of the fluid.
 
 
Author biography

Chris Wright is a research scientist who graduated from the University of Leeds in the UK with a BSc and PhD. His research focuses on the use and maintenance of heat transfer fluids in manufacturing and processing, which includes food, pharmaceutical, specialist chemicals and solar sectors.

 
Contact
Christopher Wright
Global Heat Transfer Ltd., Cold Meece Estate, Cold Meece, Staffordshire, United Kingdom
chrisw@globalgroup.org