Accessible parts have always been the drawback to scroll compressor tecnology, this is not the case with ThermaCom's new SemiScroll, as Trevor Dann explains.
Thermacom has introduced what is believed to be the first commercially available semi-hermetic scroll compressor to the UK market.

Sold under the generic name SemiScroll, this product marks a step change in the development of a second generation scroll compressor where repairability and overall lifecycle has been identified as crucially important to the environmental impact of the compressor.

The scroll compressor has increasingly been establishing dominance as the machine of first choice at the smaller end of the commercial refrigeration and ac markets.

More recent developments have seen these not only offering an increase in available duty, so that they are now competing with the lower end of the screw compressor applications on larger chiller applications, but are now available with in-built capacity control and other significant application advantages over their rival, the reciprocating compressor. Not least of all is their impressive energy efficiency when compared with a duty equivalent reciprocating compressor.

Service life and disposal

However, one major disadvantage of any fully hermetic scroll compressor is the lack of repairability. Indeed lack of spare part availability exacerbates the disadvantage this presents. The nature of the scroll is such that highly accurate design and assembly is crucial, and ThermaCom has developed new techniques to ensure accuracy can be achieved as part of its remanufacture process.

It should be noted that many users will regard compressor service life at around six to eight years as reasonable, but a typical plant installation should be expected to last around 20 years.
Simple maths implies that every Scroll compressor will require at least one or two replacements during the parent equipment lifecycle, and whereas this may be great for OEMs (all outside the UK), this does nothing for the environment nor UK plc balance of trade.

Much recent attention has been given to efforts of certain firms' ingenuity in regard to re-manufacture of scroll compressors, a technique first pioneered and documented by ThermaCom in the late 1990s. However, effective volume remanufacture has been seriously hampered by the spare part issue, buy-back schemes, which ensure failed compressors are removed from the repair market and with many internal parts protected by manufacturers' design patents, the emphasis on most fully hermetic scrolls has very much been seen as engendering a throw-away attitude once any failure has occurred.

Believed to be the first viable range of semi-hermetic scroll compressors, these machines are built to fulfil the expected parent equipment service life and need for straightforward repair, rather than disposal as a key design priority.

Not only can the SemiScroll be re-manufactured, the entire moving assembly can be stripped down simply with the compressor sitting on its bedplate. Every serviceable part is available, and active service overhaul is positively encouraged. Regardless of technique, no repair whatsoever is feasible for a fully hermetic scroll in its installed position.

This further reduces client inconvenience when initial failiure is likely to occur at around eight to ten years service.
ThermaCom, in fact, recommends a routine overhaul at the eight-year point (actual operating period is variable subject to overall system operating conditions and preferred service life is established operating hours) to avoid the consequent inconvenience and contamination issues caused by unplanned failure.

Environmental issues

Any compressor is essentially a mixed pot of numerous base metals, alloys and plastics.
Whereas some have a high intrinsic value, in the mixed metal form the scrap metal value is the lowest and the work by the metal re-processors is the highest when dealing with the separation process, so incidentally is the energy required to achieve the re-processing.

This means many scrolls will simply end up in landfill as the cost of re-processing outweighs the value of the recovered materials, then ground contamination is a serious longer term issue for the environment.

Thus the ability to avoid and minimise mixed metal scrap production of this nature is essential.

ThermaCom
0118 950 0606