Free Cooling: Helping freeze energy costs

Free cooling is a fast, effective and economic method of using low external air temperatures to assist in the cooling of water for industrial temperature control applications or in HVAC (heating, ventilation and air conditioning) systems. Within industrial temperature control applications a free cooler can be installed in series with a chiller system’s evaporator so in lower ambient conditions, partial or 100% free cooling can be achieved.   

 

According to official Met Office statistics, last year the UK experienced some of the lowest temperatures on record during the winter months, and free cooling could have saved many process or HVAC applications thousands of pounds in energy costs. When in low ambient conditions, free cooling methods remove the need to use a chiller’s compressors, utilising external cold air to cool water through a free cooling unit, which in turn can be used for a process or building’s cooling needs. 

 

Two main options are available: A chiller working alongside an independent free cooler; and a chiller with an integral free cooling coil.

Independent free cooling 

A dedicated independent free cooler is designed to maximise the energy efficiency benefits of a circuit, and is not restricted by the size of a chiller. It has a greater capacity for heat exchange as it is sized to maximise efficiency, enabling a greater area for the transfer of thermal energy.

 

An independent free cooler is installed in series with the chiller system’s evaporator, so that in lower ambient temperatures, partial or 100% free cooling can be achieved, and can result in large energy savings. This method uses naturally low ambient temperatures, and in doing so, benefits from a reduction in energy costs which can reach as much as 70%. 

 

By combining a class A energy-efficient scroll compressor chiller with an independent free cooler, maximum savings can be achieved when compared to standard screw compressor chiller.

 

As the ambient air temperature drops 3 to 5° below the required process supply water temperature, 100% free cooling can be achieved, providing an environmentally friendly and cost effective approach to process and HVAC cooling. 

 

Free cooling can be applied to both new and existing chiller systems through the use of free coolers which are balanced to provide the greatest levels of efficiency at both full and partial loads. 

 

Integral free cooling coils

Where space is limited, free cooling can be achieved through integral free cooling coils. The units are designed to offer high energy efficiency levels in all seasonal conditions and provide a compact footprint.

 

Efficiency and savings

 

Whichever avenue of free cooling is adopted, the benefits remain constant: increased reliability as each system monitors temperature and automatically switches from 100% compressor load to partial or total free cooling as climate conditions allow; use of ambient air temperature in place of compressors to facilitate free cooling and savings on running costs; and less wear and tear on chiller components and consequently a reduced life-cycle cost. 

 

Case study: Plastics

 

ICS Cool Energy has recently supplied equipment to support free cooling technology to a manufacturer of plastic window profiles in the Midlands to maximise efficiencies.

It implemented free cooling technology and supplied a one-off Imperium 2197 CA chiller with screw compressors and twin R134a refrigeration circuits, to produce 580kW cooling capacity with a supply temperature of 13°C and a return of 18°C at 28L/second. 

 

The units work with free cooling technology and can be used during spring, summer nights, autumn and winter months by using ambient air helping to save up to 68% on the plastic manufacturer’s annual energy bill. 

 

After saving in excess of £50,000 following use of the free cooling units, the plastic manufacturer has invested in a second machine in a bid to achieve further savings and fully reap the benefits that free cooling technology can offer.