HVAC


SUMMER’S HEAT - A TICKING CLOCK FOR CRITICAL COOLING SYSTEMS


Gareth Holden, Managing Director of Excalibur Energy, discusses how straight forward interventions can improve data centre cooling efficiency in older buildings, tackle summer resilience and deliver significant energy savings without breaking the bank.


If you worry that air conditioning, process chillers and refrigeration plants will struggle to maintain temperature, now might be time to take remedial action.


For new facilities summer temperatures should not be a problem, but for older buildings, the cooling load has probably increased as a result of a higher IT demand, head count etc.


This in turn puts a bigger load on the existing cooling infrastructure when performance may already be degraded, the result drives up energy consumption and can make building temperatures difficult to maintain.


The good news is that straightforward self-funding interventions can restore efficiency and resilience, reduce your energy consumption and delay more significant capital expenditure.


In some 50% of the chillers we survey, straightforward retrofit solutions can deliver 15-25% energy savings and restore resilience, with a typical return on investment of just two years. At a recent datacentre cooling project for a high street bank we delivered savings of 800,000 kwh/ year and increased resilience. So what are the most common issues and how can they be resolved?


#1 DIRTY CONDENSER COILS


Condenser fouling is a common issue. A dirty coil can easily be responsible for reducing chiller efficiency by


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5-10%. The simple solution is deep cleaning once a year, however to be done correctly the coils should be cleaned in the opposite direction to the air flow, generally this means access equipment and removal of condenser fans to remove compacted dirt. Although more time consuming, once completed, electrostatic filters on the face of the condenser ensures that efficiency is maintained, and these can be cleaned in a few hours with simple tools.


#2 HOT AIR RECIRCULATION


The proximity of taller neighbouring buildings, louvres that hide roof top chillers from view, or low speed AC fans that are unable to ‘throw’ the hot air far enough can all cause hot air recirculation.


“STRAIGHTFORWARD RETROFIT SOLUTIONS CAN DELIVER 15-25% ENERGY SAVINGS AND RESTORE RESILIENCE.”


The result is increased air temperature entering the chiller, often by 5-10o


C, meaning the chiller


is operating well outside its design conditions at an efficiency that has been reduced by 15-25%.


The replacement of existing AC condenser fans with high efficiency


EC fans and intelligent control, increases air volume and throw to improve chiller performance throughout the year.


#3 REFRIGERANT LEAKAGE


Most chillers are “critically charged”, any refrigerant leak will reduce efficiency. Unfortunately, this can go unnoticed for long periods until the loss in capacity becomes critical. A sight glass before the expansion valve should provide a visual clue and a full performance assessment will identify the issue.


#4 FAN FAILURE Condenser Fans will eventually fail


due to mechanical wear, but as they are generally mounted out of sight, failure can go undetected until the chiller cannot maintain temperatures; efficiency will have been compromised since the point of failure.


Once failures start to occur, replacement of condenser fans with high efficiency EC fans and intelligent controls becomes very cost-effective.


A full and detailed assessment with modelling of the current and modified systems is a crucial first step before any remedial action. The good news is that most interventions can be self-funded from energy saving in as little as two years and frequently it’s possible to avoid the costly wholesale replacement of existing cooling equipment.


www.excaliburenergy.co.uk twitter.com/TomorrowsFM


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