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Bruno Germany | Pixabay must be a system balance to ensure an efficient cooling or heating solution is delivered . Other factors in addition to pressure drop are the type of refrigerant , capacity and the use / application of refrigerant . Pump capability is also important and plays a role in pressure drop too .
MAINTENANCE AND BEST PRACTICES As is common in South Africa ( and many other countries ), maintenance regimes are typically an afterthought , however
Micro heat exchangers are also seeing a lot of developments in other spheres such as electronics and computing – particularly the data centre environment that has grown rapidly . every site will need some form of maintenance to ensure the proper continuing functioning of the plant and sub-systems . Proper maintenance guidelines and horror maintenance stories could cover vast articles , but the reality is that the time for neglect – which essentially translates into waste – is fast reaching its end as facility managers and owners place increasing value onto efficiency themselves , or , will in the near future be mandated to comply with certain energy efficiency standards .
This becomes quite impactful with HEX units , particularly fin and tube designs , that are by far the most commonly deployed type in the region and also form part of several unitary ranges as well as air handling units .
As this journal has reported on in quite a few prior issues to date , cleaning of coils has become imperative and with the advancement of cleaning solutions and environmentally friendly chemicals – the use of water can also be reduced significantly thus producing more savings or facility efficiency .
In the case of coil HEX units , monthly visual inspections of the units should be carried out to check that there are no line blockages and all defrost processes are working . Water build-up in drip trays can cause spillages and product damage as well as becoming a health and safety risk . If units do not defrost properly , performance will definitely deteriorate sharply and in certain cases and conditions can result in irreparable damage .
It is recommended that every three to six months units should be cleaned , all electrical connections checked and tightened , motor integrity checked , fan blades inspected for abnormal wear patterns and insulation integrity confirmed . In the plant room , all electrical and mechanical equipment should be checked and all preventative maintenance carried out timeously .
Serious problems can often be avoided if routine checks are done and any abnormal system behaviours are identified , correctly diagnosed and rectified . This may also include damage to any heat exchanger or cracks thus forming leaks . It is recommended that damaged HEX be replaced timeously as associated risks for overall plant equipment , users and related persons may be high .
In cases of plate-type HEX units , general cleaning can be carried out in two ways . Either by removing the pack and mechanically clean each plates , or through the clean in place ( CIP ) process which is the circulation of an appropriate chemical in the HEX to remove any fouling . Both methods are effective when carried out correctly . Manufacturers ’ first calls would be to try and design a unit to minimise any need for maintenance .
COMMON DESIGN ERRORS Common issues seen from a supplier ’ s point of view include incorrect pipe sizing , incorrect expansion valve sizing and fitment ( especially the bulbs ), incorrect placement of coils ( for example fitted above doorways ) or too close to walls . Another critical
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RACA Journal I January 2023 www . refrigerationandaircon . co . za