Heat Pumps Today
Info www.hydratech.co.uk www.acrjournal.uk/heat-pumps 19 T R A I N I N G Corrosion Inhibitors To minimise corrosion, it is very important for HTF to be formulated with e ective and proven inhibitors. Specifically, the inhibitor formulation should take into consideration the metals of construction, antifreeze type, susceptibility to air ingress and subsequent bacterial contamination, make-up water quality and e ectiveness of pre-commission pipework flushing and conditioning (passivation). Toxicity The toxicity of HTF formulations becomes very relevant and important where that HTF might accidentally come into contact with humans, pets, mammals and aquatic life. Emphasis here on the word ‘accidental’ as we all recognise that no business or person would deliberately contaminate a water-source or consume a chemical. Accidental exposure to HTF can occur for a number of non-deliberate reasons, including spillage, ground-loop failure (split pipe etc.), heat-pump connections weeping etc. As such it is important that the HTF be classified as non-toxic on the Safety Data Sheet (SDS). As an example; Hydratech's Thermox DTX heat pump antifreeze is classified as being non-toxic (neat). When diluted with water all chemicals become less toxic on a pro- rata basis, so when neat Thermox DTX is diluted with 72% volume water to achieve -15°C freeze-protection, it becomes even less toxic. Biodegradability To long-term prevent soil or ground-water contamination – in the event of accidental spillage or leak – it is important that HTF formulations completely biodegrade over time. I.E., they should not bio-accumulate. Our neat and diluted mixtures are classified as being 100% biodegradable and will not bio-accumulate. The five-day biochemical oxygen demand (BOD5) of a 28:72 mixture of Thermox DTX and water is 0.3 grams of oxygen for each gram of mixture. Water has a zero BOD5. Biological susceptibility and durability (aka lifespan) Our natural environment contains a myriad of di erent microbes, including bacteria, algae, fungi and protozoa, most of which are too small to be seen by the naked eye. Microbes live in air, water and soil and can multiply at exponential rates inside process cooling and heating systems if not prevented from doing so. Hence, it is crucially important for geothermal and GSHP systems to be carefully sterilised before filling with HTF, and for HTF formulations to include chemicals which neutralise and/or supress all form of microbes. Flammability Ethanol is the most often used flammable HTF found in geothermal and GSHP systems, and whilst not often selected for UK installations, Ethanol is still regularly used in Scandinavia. The fire risks of using 20% to 30% Ethanol in solution with water are obvious and as such rarely acceptable to customers or their insurers. Energy eciency and cost The combined HTF characteristics detailed above will directly impact the short, medium, and long-term energy e£ciency of associated geothermal and GSHP systems. This will, in turn, e ect the Coe£cients of Performance (CoP), Running Costs, Return on Investment (ROI-Payback) and reduction in CO 2 . Selecting poor quality or unproven HTF may save costs initially, but the long-term ramifications can be significant. Our team of sales engineers, chemists and analysts can assist with all aspects of heat transfer fluid performance, running cost, environmental impact, compatibility, and energy e£ciency. By understanding your exact application requirements.
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