UPDATE: Atmosphere 2009: Hydrocarbons in the Spotlight - Part I
30 October 2009
Mobile Air Conditioning: Hydrocarbons vs. HFC1234yf
22 December 2009
To enable the industry to get up to speed with new technologies vying to become mainstream solutions for the future, the conference focused on low carbon cooling and heating solutions, such as hydrocarbons. Nicholas Cox, Managing Director of UK-based Earthcare Products Limited presented on the “Developments and Opportunities Using Hydrocarbon Refrigerant Blends”.
Excellent performance of hydrocarbons refrigerants
Before moving on to discuss which hydrocarbon blends are suitable as HFC replacements by application, the presenter explained how the improved energy efficiency of hydrocarbons has been demonstrated in independent tests and trials by entities such as the Building Research Establishment in Watford and the ILK Institute of Dresden. In summary, the excellent performance of hydrocarbons refrigerants can be attributed to parameters such as lower compression ratio, improved heat transfer in heat exchangers and reduced system pressure losses.
Hydrocarbon blends as HFC replacements
With over 10 million car air conditioners worldwide having been converted to R290/R600a, the potential of using hydrocarbon blends to replace HFC refrigerants such as R134a, R152a and R1234yf with normal boiling point (NBP) of -26°C is already proven. Earthcare will be promoting R510A, a RE170/R600a (88.0/12.0) blend to replace HFCs that is ready before new generation HFC refrigerant R-1234yf has even reached the market. According to Cox, R510A makes a better refrigerant than R290/R600a blends as it contains dimethylether (RE170, DME) that has no temperature glide and doesn’t separate during leakage.
Earthcare proposes R-432A, an R1270/E170 (80.0/20.0) blend as an HFC R407C replacement (NPB -44°C). R-432A actually outperforms R22.
Replacing R404A (NPB -47°C) is very straightforward as the pure unblended hydrocarbon refrigerant R 1270 is pretty much a perfect match.
As replacement option to HFC R32 / MO89 (NPB -55˚C) for low temperature applications, the company proposes ECP717, an azeotrope blend of ethane (R170) and ammonia (R717) with a saturation pressure greater than R717, higher refrigerating capacity, lower compression ratio, and reduced compressor discharge temperature. The blend is optimised for blast freezer applications, but is also applicable for industrial process, food and blast freezing applications.
Britain’s largest ever hydrocarbon refrigerant chiller
Providing a real life example, Cox referred to Britain’s largest ever hydrocarbon refrigerant chiller for a building services application that Earthcare supplied in 2007 at the Church House building located less than 1km away from where the conference took place in Westminster, London. With the R290 chiller being completely uneventful since commissioning, this project has proven that larger hydrocarbon chillers can be used safely in the urban environment. Life cycle cost analysis has found that an estimated £56,990 can be saved after running the system for 10 years, compared to an HFC134a chiller.
Safety codes and guidelines
Cox referred to the UK Air Conditioning and Refrigeration Industry Board (ACRIB) ‘Guidelines for the Use of Hydrocarbon Refrigerants in Static Refrigeration and Air Conditioning Systems’ as the most practical design guide ever published. However, as these are now somewhat superseded since the publication of standard BS EN 378: 2008, the 2008 version of Institute of Refrigeration Safety Code of Practice for Refrigerating Systems Utilising A2 & A3 Refrigerants is the current guide by which this standard should be implemented.
Sparking interest from the audience
Replying to a question from the audience, Cox maintained that with economies of scale the only real extra cost with hydrocarbons is the use of leak detection. However, supposing that leak detection becomes a standard requirement for all refrigerants there will be no additional costs.
Answering to a question by another participant, Cox clarified that the Ozone Depletion Potential (ODP) of hydrocarbons is 0, while the Global Warming Potential of most hydrocarbons is 3. This is below the threshold value set by the MAC Directive that requires a GWP<150 for refrigerants used in car air conditioners, or the GWP≤5 requirement for acquiring BREEAM (BRE Environmental Assessment Method) certification.
Regarding how Earthcare went and will go about further reducing hydrocarbon charges, Cox maintained that so far reduction in charges has been achieved mainly through the use of plate heat exchangers. In the future, they will also look into the use of micro-channel heat exchanger technology, a technology expected to be CE marked for the use with hydrocarbons within 2010, as explained by a presentation provided by Güntner earlier in the day.