ThermaCom Ltd can report back upon a Project completed late in 2009 for Mssrs Rolls Royce at their prestigious London offices.
Now in 2011 we can report that not only has the prior problem of repetitive compressor failure been completely eliminated (on the systems upgraded), but by now the considerable energy saved has completely paid for the whole project.
The water chiller concerned is a French Multiclima system supplied in 2001, utilising six off reciprocating compressors installed in a compact unit, with plate heat exchangers for both Condensers and Evaporators, and using HFC R407C refrigerant.
ThermaCom involvement arose due to the significant volume of reciprocating compressors routinely failing.
Close scrutiny of the plant revealed several key concerns...
1: An inconsistent building chilled water load, presenting a wide variation in load conditions, with considerable variations in chilled water demand over a short period.
2: Low mass volume of refrigerant, also understated on the Manufacturer’s data plate.
3: Resultant system instability causing the systems to run with liquid slugging / return to the compressor – lethal for Reciprocating compressors.
Piston compressors will not tolerate significant levels of liquid refrigerant return, and those operating upon R407C are particularly prone to valve failure due to the reduced upper cylinder lubrication with Polyolester lubricants, a necessity with R407C.
ThermaCom re-selected new Hanbell Screw compressors, duty matched to the original reciprocating compressors. Not only has this completely resolved the issue of failure on the two systems upgraded, the power consumption has reduced by some 30 – 40%, and this has paid for the entire upgrade within 18 months.