SERVICE AND MAINTENANCE
A new age of heat transfer
Advances in heat transfer herald a new dawn for effi cient and cost- eff ective plant temperature control according to technical manager at Kilfrost, Michael Reynolds.
T
he design and installation of effi cient temperature control within plant systems has been subject to a lack of innovation for decades, and plant managers and installers have long-suff ered a dearth of choice. Ammonia has been used as a primary refrigerant in industrial applications for more than 150 years. It is the go-to refrigerant in many applications, including food processing and storage, building services and process applications.
Although environmentally sound, the hazards and acute toxicity associated with ammonia mean the safe design and operation of refrigeration systems is paramount. The dangers of its use are pulled sharply into focus when something goes wrong, and the death of a plant worker following a leak in 2016 only serves to underline this.
30 May 2018
It is no diff erent when it comes to secondary refrigerant systems. For decades, plant managers have had one hand tied behind their backs as they are forced to choose a fl uid that is either non- toxic but gives poor performance, or one that off ers enhanced performance but is toxic. So it could be argued that industrial temperature control is overdue a step change and that process engineers deserve better. Chemists who study the fl ow of liquids have been working hard behind the scenes to innovate. They have set their sights fi rmly on secondary refrigerants and the results are paying off . New developments promise to not only end the toxicity-versus-effi ciency dilemma once and for all, but also herald potential new options and cost savings for industry – for the fi rst time in a century and a half.
The current status quo off ers four choices of heat transfer fl uids for secondary refrigeration. ■ Mono-ethylene glycol (MEG)-based heat transfer fl uids are used in cooling systems as they off er good physical properties, but they are toxic and so pose a risk to human health if there is incidental contact with items intended for human consumption.
■ The preferred alternative by many – mono- propylene glycol (MPG) – has a safer profi le but is far less effi cient at transferring heat energy, particularly at low circulation temperatures. Plant managers are stuck with managing risk, or removing risk and removing performance.
■ Ethanol is another alternative but brings with it a high fl ame risk. When used with pressurised ammonia, the results of a leak or incident could represent an explosive combination.
www.acr-news.com
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