Energy & Power, Heating, Cooling & Drying

Process Cooling – Looking Ahead

Phil Black - PII Editor 13/04/2012

202 4 minutes read

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When deciding whether to update process cooling systems it’s important to consider the most cost-effective solution. Martin Hayward, Manager of Applied Systems, at Daikin UK argues that a little time taken during the decision-making process can pay dividends in the long run.

The old saying ‘marry in haste, repent at leisure’ could well be applied to replacing process cooling equipment. It can be tempting to make a snap decision, and indeed there may well be pressure to do so, as the need to avoid downtime is paramount. Although, a cooling system that has come to the end of its useful life quite obviously needs to be updated, to simply replace like for like is not only rash, it could end up costing a considerable amount in the long run.

Refurbish or Replace?

If needs can be met by refurbishing existing equipment then it’s still worth assessing the energy efficiency of that equipment and forecasting the short, medium and long-term costs of continuing to use it, against those of a brand new installation that meets stringent modern efficiency standards. Although the outlay of new equipment may seem high initially, when it is offset against energy efficiency gains, now possible with more modern equipment, payback times could be considerably reduced.

It is also vital to take into consideration whether a processing plant’s cooling requirements will have remained the same since the time of the last installation. Let’s face it – given that most plant needing updating is likely to have been around for a couple of decades, the chances of the plant’s requirement remaining the same over that time are slim indeed.

Although it’s common to assume that a plant’s cooling requirements will have increased, that’s not necessarily the case and very often they can reduce over time, as processes and other equipment have changed too. So, although it can be tempting to take the short term view that overhauling existing equipment, or simply replacing like-for-like is playing it safe in terms of expenditure, in many cases this could be over-specifying and using more energy than is necessary, resulting in a higher net outlay and higher energy bills.

It’s also tempting to assume that cooling needs will increase in future. However, it is often unnecessary to over-specify a system with the misguided aim of ‘future-proofing’ it. With process cooling, probably more than any other type of cooling system, it is possibly to calculate load requirements extremely accurately. Because this requirement will remain constant, no matter what the outside temperature, it’s possible to be certain what the load requirements will be and simply specify to meet that need.

This also means that there’s no need to specify more expensive equipment that has exceptional seasonal energy efficiency ratios. This is entirely different to other areas of the air conditioning industry, where seasonal efficiency ratios are not only an important consideration, but are actually written into building regulations. To specify chillers with high seasonal efficiency ratios for process cooling is not only unnecessary due to small seasonal load variation, it may push up costs.

An energy efficient option…..

One area that is worth considering, however, is whether water-cooled units using a geothermal system could improve energy efficiency. Although the majority of the chiller market is made up of air-cooled systems, for process cooling, water-cooled units are a highly reliable solution thanks to their superior stability and wide temperature control range.

The high-performance models, such as those from Daikin UK with capacities of more than 177 kW deliver precise capacity control from 12.5% to 100%. They are fully capable of withstanding the demanding conditions typical of industrial applications.

Used in conjunction with a geothermal system, water-cooled systems disperse excess heat resulting from the production process into the ground via boreholes. Obviously there is an extra initial outlay for the plant but from an energy efficiency point-of-view they could well prove the most efficient solution and payback periods can be attractive too.

“Free” cooling is another area that could provide potential energy savings. As process cooling requires a constant year-round load, systems designed to utilise the outside air temperature to remove excess heat can prove cost effective. As these systems use “free” cold air, plentiful in the UK’s winter months, they can prove to be a highly cost effective and energy efficient solution.

Consideration also needs to be taken about the cost of potential down-time of any cooling system. There are several ways this potential problem can be addressed: by the provision of stand-by machines; by designing in space to install temporary plant when required; or by specifying chillers that have multiple refrigeration circuits and multiple compressors. The latter option may well be seen as the most cost effective, however, the reduced energy efficiency of designing in excess capacity will, of course, impact upon the energy efficiency.

Whatever the application it is vital to analyse right from the start the precise cooling requirement of any given plant. This can result in lower carbon emissions and reduced energy bills. It’s also quite likely that the cost benefits of replacing older systems with carefully chosen new ones instead of refurbishment will be the most cost-effective solution and this option should always be approached with an open mind whilst paying close attention to load requirements and the corresponding efficiency levels of various solutions at these loads.

Daikin UK
Weybridge, Surrey
Can be contacted on:
Tel: 0845 649360
E-mail: sales@daikin.co.uk
www.daikin.co.uk