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Cooling systems for reduced energy use

Packaging Professional magazine
,
14 May 2010

Careful design can produce affordable upgrades to cooling systems for meeting energy targets. Nigel Hallett, Managing Director of process cooling company IsoCool Ltd, Great Notley, UK, explains.

Rising fuel prices and the economic downturn have placed operating costs under immense scrutiny, and environmental concerns have added to the pressure. Not only are manufacturers working towards targets set by the UK’s Climate Change Agreement, but they are also expected to demonstrate ‘eco’-credentials as a matter of course.

This means reducing the amount of water used, demonstrating responsible procurement and using technology that can deliver high efficiency and improved performance – quite a tall order when taking into account the industrial processes involved in a typical packaging plant. For example, a chiller that is 10 years-old or more could consume £578,400 kWh/year, costing over £37,000 to run, making it difficult to achieve energy targets and possibly incurring penalties.

The future of plant process cooling does not necessarily involve the wholesale removal of existing systems. A sensible whole system approach must consider a range of factors, such as the carbon footprint of manufacturing new equipment and the sustainability that can be achieved by small-scale modifications.

Keeping cool

Free cooling technology has made this environmentally and financially sound approach possible. During low ambient conditions, the system uses the surplus capacity from an ambient cooling system, such as cooling towers, air blast or adiabatic coolers, to pre-cool water returning from the chilled water circuit before it reaches the refrigeration plant, reducing energy consumption, extending the lifespan of its components and lowering CO2 emissions.

Free cooling has repaid dividends at Alma Products in Runcorn, UK, a provider of extrusion, thermoforming and container printing services to the food industry. A redundant cooling tower has been recommissioned using existing pumps and by retrofitting a separate plate heat exchanger to the Montair chiller system. The tower now serves as a free cooling source when the ambient drops below 16°C. Below 10°C the plant runs on 100% free cooling. The goal was to reduce Alma Products’ operating expenses by 63%, and the system is currently on target, suggesting that the upgrade will have paid for itself within 15 months.

Climate conditions means that free cooling is restricted to Northern Europe. However, advantages include the potential use of funding sources such as Carbon Trust loans to offset initial investment. Another benefit is that system shutdown time is minimised as cooling systems can be upgraded at any time or installed at awkward locations removed from the main process.

Manufacturers are working to overcome the seasonal limitation of free cooling – designing single unit systems that save space and cut maintenance costs. For example, IsoCool Ltd, Great Notley, UK, is about to launch a new dual system modular adiabatic dry cooler which automatically operates as an air blast (free) cooler in cold weather and an adiabatic cooler during the summer months. The self-draining version works without glycol, eradicating the legionnaire risk.

Design is also focusing on water saving. A global water disclosure project, led by the Carbon Disclosure Project, London, UK, will start this year, asking the biggest companies to reveal the implications for their businesses of tightening availability and rising costs of water. In turn, these companies will chase supply chain partners, including packaging providers, for data on water usage and future targets. The implications for packaging plants are clear.

Packaged options

As a variation on the theme of free cooling, traditional technologies such as the heat exchanger are also seeing a revival. A simple yet highly effective source of pre-cooling, packaged heat exchangers connect mould and hydraulic cooling circuits using intelligent software, allowing energy transfer between the systems without mixing.

Wherever possible a whole system approach, which uses natural resources as a free source of cooling, should be taken.

Further information: IsoCool Ltd