Free cooling – the cheapest and greenest way to provide cooling

By: Dave Palmer, general manager for the UK and Ireland at ICS Cool Energy

Improving industrial facilities’ systems performance has the attention of businesses and government organizations with good reason. Energy prices continue to rise. Organizations are focused on doing more with less, improving productivity, shrinking their environmental footprint and spending scarce capital budgets in ways that will provide the best return on investment.

The need to reduce economic and environmental impacts are making it important for manufacturers to implement strategies to reduce their energy consumption without hampering their critical function.

Process cooling technology continues to advance along with a sharper focus on total costs, energy efficiency and sustainability. Achieving the full potential of a process cooling system opens opportunities to save money and improve operational efficiency but requires a whole lifecycle approach that recognizes opportunities to reduce total costs of a system, rather than focusing only on first costs.

WHAT IS FREE COOLING?

The concept of free cooling is nothing new. In the old days, we cooled down our cars heated up by the sun by opening the windows, as the outside was colder than the inside. To some it may come as a surprise, but the same principle applies to free cooling in an industrial environment.

Any company or organisation using an externally sited chiller to cool their process can benefit from free cooling. Whenever the outside temperature is low enough to cool down the process fluid without the intervention of a chiller (mechanical cooling), we can implement a free cooling solution.  This can be in the form of partial free cooling (where the chiller’s compressors are still doing some of the work to cool) to full free cooling (where the full load on the chiller is offset). In contrast, an externally sited chiller’s compressors with no free cooling capabilities will be working flat out to achieve the same.

Depending on the time of the year, as the ambient air temperature continues to fall, the amount of process heat taken out of the process fluid by the air increases, progressively reducing the load on the chiller. At 5 degrees Celsius below the process supply fluid temperature, all the process heat is removed by the ambient air in the free cooler – providing full free cooling. This makes free cooling the cheapest and greenest way to provide cooling.

 

WHEN AND HOW DOES FREE COOLING WORK?

In the UK, Ireland and much of Western Europe, the relatively cool climate and ambient temperatures allow for partial or full free cooling for much of the year. This means that substantial energy savings can be achieved particularly between the months of October and April, in some cases reaching up to 80% electricity savings.

When the ambient air temperature drops just 1 degree Celsius below the process fluid return temperature, a 3-way valve diverts the returning process fluid through the free cooling coil in which the cooler ambient air removes process heat and cools the returning fluid (partial free cooling), it then flows through the chiller’s evaporator where the required set point temperatures are achieved – easing the demand on your chiller’s components and extending their operational life. Full free cooling is achieved in case when the ambient air temperature continues to fall, and the returning fluid from the free cooler meets the required process temperature.

DO YOU REQUIRE A NEW CHILLER OR CAN A FREE COOLING SOLUTION BE ADDED TO EXISTING PLANT?

Free cooling works with either a chiller with a built-in free cooling coil or a free cooler working in series with a chiller. The latter is more efficient, due to the larger surface area provided by the air cooler.

A remote free cooler is designed to do nothing but provide free cooling and has its own purpose built control system and 3-way valve and bypass system and therefore is a simple and reliable way to give maximum savings and quick payback.

As the system is fully packaged, complete with integral controls, 3-way valve and actuator, and bypass pipe work, they can be easily installed on existing systems as well as new builds. Additionally, no communication between the free cooler and chiller is necessary, which in typical process cooling systems, allows to offload chillers for up to 90% of the year.

You can choose from solutions with multiple fixed fan speeds, inverter speed control and Electronically Commutated (EC) fans for varying noise applications. The units control panels are designed to offer ease of use with a ‘plug and play’ solution and 4G connectivity. They can be configured to meet your individual project requirements such as low noise, space restrictions and aesthetics and integrate with BMS.

THE BOTTOM LINE BENEFITS OF FREE COOLING

In conclusion, free cooling is a concrete solution that will reduce mechanical energy consumption, lower the carbon footprint, reduce load on mechanical parts and therefore reduce maintenance cost and extend life of your cooling equipment. In case of a chiller, smaller load demands can also lessen the depreciation value of the unit over its lifetime. It is a solution that is easy to retrofit (space permitting) and can deliver a real quick payback for the new equipment.

Additionally, manufacturers looking to add free cooling into their systems, but trying to avoid capital investments, have the opportunity to benefit from programs like the ICS Cool Energy Flex. The equipment-as-a-service offer comprising a monthly package provides customers with running cost reductions versus the existing plant running costs. This type of a long-term solution is a fixed, hard-piped install to the customer’s process, offering energy savings, maintenance and annual cooling circuit fluid analysis and the option to upgrade as technologies improve. The flexibility of this business model can be a significant ingredient to the decision process and making a step into a more sustainable cooling.

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SIDEBARS/CASE STUDIES

FREE COOLING DELIVERS MASSIVE SAVINGS FOR SPECIALITY CHEMICAL MANUFACTURER

Three air cooled chillers and a 360kW free cooler system resulting in 42% annual energy savings for a chemical manufacturer. This means a return on investment in 6-9 months and prolonged chiller lifetime as a result of reduction in use and a comprehensive planned preventive maintenance (PPM) contract

The customer, a leading manufacturer of speciality chemicals, was planning to move their existing bead mill process (comprising 7 mills) to a new manufacturing site that would be suitable for expansion to 16 mills. In the previous set up, they had been cooling each bead mill with individual chillers but wanted to increase the energy efficiency of the system through a new chilled water ring served by larger chillers.

THE SOLUTION

A site visit determined the process required a maximum design load of 358kW of cooling and pressure independent control valves at each bead mill connection to allow for precise flow control. To achieve the overall aim of improving efficiency and saving energy, detailed and comprehensive design brief recommended three iC 660 air cooled i-Chillers (capable of managing the total load on a Duty/Duty/Assist operation) with a 360KW free cooler system.

THE RESULT

Thanks to the cooling system upgrade and the addition of the free cooler, the customer is using less power during lower ambient conditions, which translates to over 210,000 kWh of energy and £21,000 saved annually.  Further benefits include far lower plant running costs, lower carbon footprint of their production facility, higher coefficient of performance, large long term savings, return on investment within 6-9 months and prolonged chiller lifetime as a result of 1) reduction in use and 2) planned preventative maintenance contract taken out at point of purchase.

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 NEW CHILLER AND FREE COOLER INSTALLATION FOR PRINTING PRESS SAVES 43% ON ENERGY

A global leader in the gaming and lotteries industry, required an energy efficient cooling solution for a new printing press. They needed a system comprising a new chiller as well as a standby unit for 100% back up in case of failure, and free cooling.

THE SOLUTION

To make the cooling of the printing press as energy efficient as possible, ICS Cool Energy specified two Aptus air-cooled / Eco-Design compliant chillers, each capable of extracting 550kW as well as a free cooler to run alongside the chiller.

A full, turnkey installation followed, including  delivery to site, pipework, thermal insulation, circulating pumps, pump control panel, 4 off 215L glycol drums, electrical installation and contract lift.

The Service team took care of the final commissioning of the new cooling equipment and put in place a planned preventative maintenance contract from the outset to give the customer maximum peace of mind.

THE RESULT

The running cost analysis detailed a saving of 43% energy against their previous set up, contributing to:

• Lower plant running costs
• Lower carbon footprint of facility
• Larger long term financial savings
• Prolonged chiller lifetime from a reduction in use and positive effects on servicing as a result

Caption: The cooling system upgrade generates 43% of energy savings every year against their previous set up

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FREE COOLING HELPS CNC & WIRE EDM COMPANY ACHIEVE £17,500 ANNUAL SAVINGS

Expanding their business operations, a leading CNC (computer numerical control) and Wire EDM (electrical discharge machining) company operating a 5-axis laser system and around 30 CNC EDM and Wire EDM machines to produce precise machined components for the aerospace industry – decided to move their operations and manufacturing equipment from two different into a single, larger factory.

In the previous set up all the machines were split over two factory units and the cooling had been provided by individual small chillers that were installed over the years.

THE SOLUTION

As a result of a detailed site survey and running cost analysis, which included determining the required exact total cooling load of 133kW and 18 – 20 degrees Celsius supply temperature,  ICS Cool Energy installed a single ic540 i-Chiller with a three fan standalone free cooler of 140kW. The offered solution also included 3 years parts warranty on the new equipment, planned preventative maintenance package in place and a total supply and installation package.

The chiller and free cooler were sited externally at the new site and the pipework was installed at ceiling level on two floors to serve existing and future machines (allowing the potential cooling of up to 36 machines).

THE RESULT

Following the installation, the running cost analysis detailed a saving of 71% against a chiller alone and based on 24/7 operation offered approximately 9 months payback on the free cooler.

The customer calculated the energy cost savings around £17,500 annually, with further energy savings provided by inverter-controlled fans on the free cooler. The customer also benefits from:

• automatic control of the free cooler via a modulating valve that optimises operation of the free cooling unit
• Reduced chiller running time equalling reduced service costs and extending chiller life span
• No heat generated from cooling plant inside the factory due to the outdoors location of the units.