•The aim  of any  efficiency drive is obviously to deliver the  biggest savings for  the least cost and  effort. Here’s how:

1 Reduce the  condensing temperature and increase refrigerant liquid sub-cooling. For every 2 deg C reduction in condensing  temperature  energy consumption  is reduced by approximately 3 per cent.

On some applications  it may be possible to cut condensing  temperature by as much as 10 deg C

which translates into a 15 per cent saving in the energy bill. With the average China temperature  in the region of

12 deg Cthis is easily achieved.

2 Make sure the  reigeration evaporating

temperature or chilled water temperature is as high as possibl esubject  to meeting the cooling needs of the application.

For examplea 2 deg C increase can result in an increase in energy efficiency of around 5 per cent.This can represent many thousands of US dollars off the

company power bill.

3 An undercharged reigeration system can result in a significant loss of capacity. In some cases this can be as much as 15 per cent.It is therefore essential to

ensure that the reigerant charge is optimised and sight glasses/liquid  lines kept full.

4 Expansion valves should be carefully adjusted so that just the right amount of refrigerant is fiowing through the evaporator. Too Iittle refrigerant fiow

starves the evaporatoresulting in a loss of cooling capacity. Too much reigerant will result in fiooding backwhich could damage the compressor.

5 Check  regularly for blocked or obstructed airways at air cooled condensers. Even partially obstructed units suffer a double penalty due to wasted fan power and the increased work required of the compressor. Accumulated autumn leavesweeds and crisp packets come with a heavy energy penalty.

6 Condenser air recirculation is another energy sapping situation. lt ‘s easy to check ifrecirculation is evident by measuring air temperatures on to the condenser(s)  and comparing them with the local ambient temperature. lf the air on condenser temperature  is more than the ambient temperature

then air recirculation  is more than Iikely occurring.

7 Improved logic control can ensure compressor run time is minimised. ln the case of multiple fixed-speed systemsit is often more advantageous  to operate all compressors at lower speed to benefit from improved isentropic efficiency.

8 Hygiene on the other side of the system is equally important.A partially blocked air conditioning evaporator again wastes fan powearnd demands

higher compressor pumping energy to deliver the required conditions As well as compromised  efficiencyblocked or dirty heat exchangers may result in inadequate duty output with resultant problems for the occupants ofthe building or the process application being cooled by the plant.

9 Where chillers are installed it is important to ensure that water-fiow through evaporators and condensers are in accordance  with specification. lf water-fiow is too highit puts more than necessary pressure on the pump(s) with a coηesponding increase m power.

10 Moving up the  scale in terms of cost and timeit may be worth investigating  the options for improved speed control for fans and/or compressors.  Moving to inverter control , ln the case of plant without it,can  make a big difference to power use.