PROCESS COOLING FEATURE SMALL CHANGES, BIG BENEFITS


Here, Richard Metcalfe, sales director for ICS Cool Energy, outlines how making just a few modifications to a chiller can start cutting energy consumption and boosting performance


F


rom an energy usage point of view, a chiller can be one of the most energy-


intensive pieces of equipment in a factory. With process cooling costs responsible for a significant volume of an industrial end- user’s utility bill, many have accepted that high cooling costs are a necessary evil that must – by and large – be taken on the chin. However, this is not the case. To take it right back to basics, a chiller is


effectively comprised of two halves – high pressure and low pressure – and the closer those two sides are to each other, the more efficient the chiller. However, the quality of the components


that make up a chiller can go a long way to improving the efficiency of a unit over the course of its operational life. There are a number of key components within a chiller that will impact performance and energy consumption. Some of these are intended to last for the chiller’s operational life, and so should be given extra scrutiny during the specification stage; while others can be retrofitted throughout its working life, to further improve the efficiency of the system.


and pressures, such as those required by processes in the plastics and rubber, and chemical and pharmaceutical industries. Using a heat exchanger with multiple


‘passes’, such as a two or four-pass model, is likely to be much more efficient than single pass or two-part variants. The ‘pass’ refers to the number of times the heat transfer fluid is required to pass through the heat exchanger to reach the desired temperature. Crucially they can be retrofitted to existing chillers. However, they are not compatible with all models, so it is advisable to discuss any potential upgrades with your maintenance partner, or the chiller’s manufacturer. • Compressors The compressor is another area of a


chiller that can be responsible for a significant volume of energy consumption. However, many high-efficiency compressors are available, both as a new installations or a retrofit upgrade. Turbocor compressors, which use


magnetic bearings to offer improved efficiency and reliability levels by reducing moving parts; as well as inverter-driven


‘The quality of the components that make up a chiller can go a long way to improving the efficiency of a unit over the course of its operational life’


Either way, the following components


have the potential to make significant reductions to a chiller’s energy consumption, and subsequently, an industrial end-user’s utility bills. • Pumps Pumps are one of the biggest users of


energy in any cooling application – not just chillers, but cooling towers too. Variable speed pumps are key to


matching the flow of the system to the required capacity, and avoid wasted power and energy compared to traditional on/off pumps. They have the potential to save up to 50% on pump energy compared to fixed-speed units. What’s more, the cost and power output savings are magnified on larger systems with pumps greater in capacity than 15kW. • Heat exchanger (shell & tube) Heat exchangers are critical to the


successful operation of a chiller. Shell and tube heat exchangers pose several advantages over plated heat exchangers. Not only are they typically less expensive than a plate heat exchanger, but they can cope with higher operating temperatures


/ PROCESS&CONTROL


scroll and screw compressors with built-in variable speed drives, can offer energy savings of 50-60% compared to standard models. What’s more, a -3˚C difference in operating temperature between screw and turbocor compressors can lead to energy savings of circa 56%. • Condensers Micro-channel condensers, while not


The process-heavy nature of the UK’s industrial landscape means getting a firm grip of a plant’s temperature control systems can quickly result in a reduction of energy consumption and consequently, utility bills


able to reduce energy consumption directly, can reduce the volume of refrigerant needed which will take further cost out of the system and promote a more environmentally-friendly operation. They also help equipment comply with the latest requirements of both the F-Gas legislation and Ecodesign Directive. • Electronic Expansion Valves While electronic expansion valves (EEVs)


are not yet standard on most chillers, they are much more efficient than mechanical equivalents as they are able to operate on a lower pressure ratio without impacting the functionality of the chiller. What’s more, EEVs have the potential to


save circa 12% energy a year compared to mechanical valves. Again, they can easily be retrofitted onto an existing chiller. • EC fans EC (Electronically Commutated) fans


operate using a DC motor rather than an AC motor, which in turn not only offers a more efficient fan performance, but also noise levels that can be 4-5 dba lower. Engineers are often put-off by the


Given the number of fans that can be found on a chiller, it makes sense to invest in efficient models


investment in EC fans given the number of fans that can be found on a chiller. However, with a payback period of just 6- 12 months, industrial end-users can start to make permanent energy savings from just the second year of operation. If variable fan speed control is added, a further 12-14% energy savings can be made compared to standard on/off fan speed control. While there are a number of ways of


reducing energy consumption in process cooling, one of the most effective is evaluate the performance of a chiller itself. Many of the energy-intensive components, such as compressors, pumps and heat exchangers, can be upgraded throughout the operational life of a chiller. What’s more, all of these parts have the potential to not only pay for themselves given their comparatively short payback times, but to deliver sustained energy savings for many years to come.


ICS Cool Energy www.icscoolenergy.com


PROCESS & CONTROL | NOVEMBER 2018 17


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