The use of synthetic aromatic heat transfer fluids is highly inevitable in liquid heat transfer systems. Synthetic fluids are best utilized in systems where natural fluids cannot function, such as systems operating low temperatures and systems having temperatures above 600°F, and (if possible) in the vapor phase.
Following are some of the reasons for considering the use of a heat transfer fluid produced from natural feedstock, i.e. the Paratherm NF® non-fouling, non-toxic fluid.
The procurement cost of many synthetic fluids is higher than that of the NF fluid by a slight or substantial amount. The cost of handling and disposal also adds notably to this cost.
Synthetic fluids usually provide equal-to-greater film coefficients than the NF fluid at medium temperatures. On the contrary, when the temperature starts to increase, this difference gets significantly reduced until Paratherm’s coefficients surpass the coefficients of most of the synthetic fluids at the higher end of the temperature range, making the NF fluid more efficient. It should be noted that greater film coefficients correspond to greater availability of BTUs at the user surface.
Longer Fluid Life
Almost all the heat transfer fluids can provide better service for reasonable periods of time if they are properly specified and operated in well-designed systems. Nevertheless, this service period is drastically reduced due to the degradation caused as a result of oxidation, contamination, and overheating. The NF fluid is significantly more forgiving because of its non-fouling characteristic. It has a service life equal to or greater than that of the synthetic fluids.
In contrast to most of the synthetic fluids that are considerably or somewhat toxic, the NF fluid is absolutely non-toxic which means it is certified to be of food-grade. As indicated by the Safety Data Sheets for aromatic fluids, little amount of benzene gas may be formed and get accumulated in the expansion tank if the fluid is intensely overheated, which is often the direct consequence of low flows at the heated surface. Overheating can occur at the fluid’s film layer even at moderate or lower fluid temperatures. However, very little change is observed in the fluid’s bulk temperature.
While using aromatic fluids, care must be taken to ensure that the expansion tank is vented to an area in which the fumes cannot get accumulated. The fluid’s Material Safety Data Sheet (MSDS) must be cautiously reviewed for toxicity information related to respiratory contact, skin contact, and ingestion. Nearly all synthetic fluids are known to cause respiratory problems and skin dermatitis. On the contrary, the NF fluid has been known to actually soften the skin and has no odor.
While care is always taken to prevent the entry of fluids into the atmosphere, accidents do and can occur at times. To prevent this, it is optimal to follow the hazardous or regulated waste procedures for the clean-up and disposal of most of the synthetic fluids. On the contrary, the simple clean-up procedures similar to those used for light lube oils can be followed in the case of NF fluid release. Moreover, contaminated or used NF fluid can be safely compounded with used-up lube oils and sent to the local oil recycler (EPA, citation 57FR21524). This process aids in conserving the precious landfill space and the natural resources. In addition, the NF fluid has also passed rigorous Bioassay for three species such as saltwater shrimp, rainbow trout, and freshwater shrimp.
Fouling, which has been noticed in the case of almost all synthetic fluids, normally occurs when fluid flow drops at the heated surfaces. Consequently, less heat is removed, the heat balance is disrupted, and the film temperature starts to increase quickly. Such a high heat flux surpasses the strength of the fluid’s chemical bonds and causes breakage of the bonds, resulting in the formation of amorphous, fine “sooty” carbon. A major portion of the carbon immediately gets adhered to the heated surfaces and is baked, thus producing insulating layers.
In contrast, the NF fluid releases non-adherent carbon granules even under the same severe heating conditions. These carbon granules remain suspended and can be easily filtered. This feature is specifically significant in electrically heated systems in which hard baked-on carbon deposits occur very often.
Synthetic heat transfer fluids release mild to heavy odor even when operated within their normal temperature range. On the contrary, the NF fluid releases no odor.
For many years, the NF fluid has been effectively used in a wide range of challenging applications involved in the processing of pharmaceuticals, petroleum, oils, chemicals, adhesives, and food. It allows uniform and accurate temperature control in applications such as die casting, laminating, injection molding, calendering, curing, printing, and drying.
The Paratherm NF® non-fouling, non- toxic fluid has been recommended, approved, and/or specified by various original equipment manufacturers, whose equipment have been used in the aforementioned processes.
This information has been sourced, reviewed and adapted from materials provided by Paratherm.
For more information on this source, please visit Paratherm.