The business of chillers: selection tips
Chiller Feature
Chillers come in all shapes, sizes and configurations which means the selection process isnt always a simple one. CCNs Sandra Van Dijk goes straight to the source and talks to executives that are in the business of chillers to get tips on chiller selection.
While chiller selection is often dictated by capacity, there are a myriad of other factors to think about especially when it comes to the best way to control, operate and calculate system operational costs.
While block load determines overall capacity, part load determines the number and quantity of chillers required.
A block load will take into account building diversity and load changes based on exposure, internal and external loads, and building schedules because all portions of the building will not be peaking simultaneously.
The function of a space may also dictate sizing and plant reliability. Essential services, such as hospitals and data centres, will require a high level of redundancy and that means backup chillers for reliability.
Cosair managing director Matthew Cosgrove says the location of the equipment will determine if the chiller is air cooled or water cooled.
Location could also take into account things like temperature extremes for the chiller operation and corrosive or dirt laden environments that will influence particular features for the chiller, he says.
The type of facility being served by the chiller and the load profile will influence selection for a single or multiple chillers and determine load.
On the subject of efficiency, Cosgrove says chillers are built with various components.
Compressors, for example, may be centrifugal, screw or inverter screw, scroll or inverter scroll, and they all have different efficiency levels and initial cost implications.
The initial cost verses the operating efficiency needs to be evaluated keeping in mind client requirements for the project, Cosgrove says.
In determining capacity, its important to consider the minimum load requirements of the system, how the chiller will provide this minimum capacity without excessive cycling of the compressors.
Water volume plays an important part of ensuring the ability of the chiller to provide the minimum capacity requirement without excessive compressor cycling while maintaining the water temperature within the required limits, he says.
The controllers and software of chillers are what monitors and controls the chiller components to achieve the final water conditions, hence it is important to have redundancy not only in the major chiller components but also in the controls. It is also important that the chiller continues to operate outside the design ambient temperatures, particularly when there is no redundancy in the system.
Not all chillers are designed to remain operating well outside the normal design ambient conditions; as such this point needs to be considered in relation to the specific site operating requirements, Cosgrove explains.
The selected equipment should be designed to efficiently and reliably produce the nominated capacity and manufactured with high quality components plus provide good access for service and maintenance.
Heatcrafts business development manager, Graeme Stuart, agrees that capacity is a critical factor when determining selection.
Customers also need to consider if the chiller is capable of performing the tasks required of it and whether the chiller should be air cooled or water cooled, he says. The most important features are energy efficiency, the inclusion of VSD fans and motors and low refrigerant charge.
Stuart says the selection process really comes down to finding chillers with the features and benefits best suited to the application.
He says full support from the chiller supplier should also be assessed.
For example, Heatcraft offer assistance with commissioning, full technical support nationwide and full spare parts support nationwide, Stuart says.
GEA Refrigeration sales manager, Greg Clements, suggests a cradle to the grave approach to selecting a chiller.
He says its important to always do your homework before proceeding.
When focusing on the price, dont just focus on the upfront price but take a cradle-to-grave approach. Its a big investment that will be in play for a long time, Clements warns.
Its not just about capacity. Having made an informed decision about the price from a cradle to grave viewpoint, assess other critical factors such as the brand, local ongoing support, spare parts, engineering back up, energy efficiency, redundancy and the ability to accommodate future expansion, just to name a few.
Clements admits that buying decisions can be subjective. If you are an accountant, the most feature will be the price whereas a project engineer will be more interested in energy efficiency and redundancy while a plant engineer will focus on support, he says.
To summarise, the most important feature in a chiller is to have as many ticks in boxes relative to delivering value to the customer.
For James Su, sales manager at the Blue Box Group, chiller selection is about understanding client expectations.
It means that you ask as many questions as possible in the early stages to draw up a priority list, Su says.
There are many chillers available in the Australian market that have different efficiency levels, noise levels and other specifications and sourcing from various countries around the globe willl have different cost implications.
If energy efficiency is on the top of the list, then its best to select a Eurovent Class A chiller.
Apart from capacity, Su says energy efficiency is a key factor in chiller selection.
Although MEPS has set a minimum efficiency standard for all chillers, there are many options that are available to enhance overall chiller efficiency. Things like VSD, EEV (Electronic Expansion Valve), Heat Recovery or Free Cooling, he says.
Other key factors are delivery lead time, price and country of origin. For example chillers made in the United States, Europe and Australia are perceived to be of better quality than chillers made in Asia where components may not be of a high standard.
"Each application is different and you do not see an identical chiller selected on two different jobs, he says.
From a product perspective, I believe that high efficiency, competitive price and superior reliability are the three underpinning features of a good chiller.
Quality engineering
Chiller suppliers need to be proactive from start to finish to ensure customers get the most appropriate chiller for their needs, according to Summit Matsu Chillers general manager, Daniel Rollston. It must suit the application, he says.
Many of our customers require chillers for cooling processes or for various industrial applications such as mining or manufacturing, so an important question which they should ask a potential supplier is whether the chiller can withstand heavy-duty continual industrial use, Rollston says.
An industrial chiller differs from a chiller designed for air-conditioning applications in terms of the redundancy of parts, and depending on your application we optimise the selection of condensers, compressors, evaporators, expansion devices and controls to minimise power usage and increase reliability.
Operating temperature and the local climate where the chiller will be operating will have an impact on its performance, so ensure that the chiller is rated for your specific conditions.
Rollston says local parts availability and support should also be considered when making a chiller selection.
Downtime as a result of a breakdown can be very costly, he says, so be assured that parts can be sourced locally for repairs.
Make sure the supplier has service technicians that can come to you to perform the work as well as providing regular scheduled maintenance to keep the chillers performing at optimal levels, Rollston says.
Capacity is certainly an important factor, and assessing this accurately at the beginning of your engagement with a chiller supplier is vital for a successful implementation.
In addition to capacity, consider the quality of the chiller design, the parts being used and all aspects relating to service and repairs when making your decision.
The quality of the engineering and parts is paramount as this results in a high quality, reliable product. Bigger is not always better, as it can translate to higher energy bills as a result of power wastage.
The following factors need to be considered before selecting a chiller
1. The required cooling capacity.
2. Entering fluid temperatures.
3. Leaving fluid temperature.
4. Flow rate of fluid to be circulated.
5. Design ambient air temperature.
6. Location of chiller.
7. Application eg process or air conditioning
- Provided by Heatcraft
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