Reducing energy consumption is a crucial component of our global effort to reduce carbon emissions. The more efficient we can make our processes, the lower our carbon output and the more sustainable we become.
In industry, there is not one golden rule to reduce consumption, rather it’s a combination of multiple small wins, that when combined, create a system that is much more economically and environmentally friendly.
Any industry that requires a cooling process can benefit from more sustainable cooling, such as free cooling.
What is free cooling?
Free cooling uses low external air temperatures to assist in cooling water for industrial temperature control applications or in HVAC systems.
It is fast, effective and extremely economical, particularly in areas with cold seasons, such as the UK, where energy savings of up to 80% can be achieved.
How does free cooling work?
The use of free cooling in an industrial temperature control application differs from an environmental cooling solution, as fresh ambient air cannot be drawn straight into the cooling circuit.
Therefore, to harness the benefits of the low ambient temperatures, a free cooling coil needs to be introduced to the circuit.
When the ambient air temperature drops just 1°C 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.
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°C below the process supply fluid temperature, all the process heat is removed by the ambient air in the free cooler – providing full free cooling.
In The UK, Ireland and much of Western Europe, our relatively cool climate allows 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 up to 80% electricity savings.
Type of free cooling
A standalone free cooling system sees an independent free cooling unit working alongside an electro-mechanical chiller.
As the system comprises at least two units, it requires a greater amount of space given the footprint of the equipment, and the subsequent need to allow air to circulate around the units. However, the increased footprint means a larger surface area, which can allow better part loading to be achieved – akin to an 80% saving on running costs a year.
What’s more, standalone free cooling systems have the capacity to provide 100% free cooling at a higher ambient air temperature than integrated free cooling chillers. From a cap-ex perspective, a standalone free cooling system can work alongside an existing chiller.
As such, start-up costs can be lower as the original chiller can remain in service.
Integrated free cooling units are a viable option for sites which may not have the available floor space to accommodate standalone units.
It is ideal for high capacity systems with limited available footprint, as a standalone system on that scale would require significant floorspace to accommodate the necessary equipment.
However, for an integrated system to achieve 100% free cooling, the ambient air temperature needs to be lower; usually in the region of 2°C, compared to 5°C for standalone systems.
Do I require a new chiller for free cooling to work?
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 and we are able to offer both options.
A remote free cooler is designed to do nothing but provide free cooling and has its own purpose built control system, a 3-way valve and bypass system. Therefore it 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 & actuator and bypass pipe work, they can be easily installed on existing systems as well as new builds.
No communication between the free cooler and chiller is necessary. In typical process cooling systems, chillers can be offloaded for up to 90% of the year.
Free cooling examples
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.
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).
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.
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 new chilled water rings served by larger chillers.
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, a 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.
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.
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