Several technical presentations at the 9th Gustav Lorentzen Conference in Sydney highlighted the merits of hydrocarbons in a range of applications from chillers to room air conditioners and refrigerators in remote areas.
The 9th edition of the Gustav Lorentzen conference on Natural Working Fluids has attracted close to 170 participants from 26 countries that gathered in Sydney to discuss latest developments regarding natural refrigerants, including hydrocarbons.
Safe use of hydrocarbon based chillers and application solution, Alexander Pachai, Johnson Controls Denmark
After discussing safety provision of standard EN-378:2007, such as ensuring that the air in the machine room cannot reach the lower explosion limit, Pachai provided an example of a project, whereby a little cascade unit based on an air-cooled propane unit condensating CO2 that circulates to two rooms with 1@+4°C, 3 kW and 1@-18°C, 3.5 kW has been installed. The system was chosen for reasons of considerable energy savings of 28% above the system normally used. The very limited R290 circuit is kept on the roof, while all piping going into the building contains R744 (CO2) only. This design resulted in a 3 kg R290 and 12 kg CO2 charge.
Moving on to larger systems, Pachai discussed the case of a system on R1270 (propylene) - a refrigerant that has a natural smell - the efficiency of which exceeds the R404A based system it replaced. The high temperature stage is water-cooled and includes both an air-cooled de-superheater loop and a water-cooled condenser in the container. The total cooling capacity for both containers is 500 kW covering both negative and positive temperatures.
He then provided the audience with a chart comparing the average Coefficient of Performance (COP) of different Eurovent certified chillers/ to tested chillers, demonstrating the merits of hydrocarbons in terms of efficiency. Regarding system cost, Pachai maintained that with the taxes introduced on HFC refrigerants in Scandinavia the price of hydrocarbon compared to HFC systems are just about the same for the customer/user. Without the tax the hydrocarbon type would be a little more expensive initially but with a short payback period thanks to energy savings.
Before concluding, the presenter asserted that there is not much difference in the way hydrocarbon systems are built and which components go into the systems when compared to HFC systems. The main difference is the positioning of the different components on the unit, as for example safety relief valves must be carefully positioned where the release will not be able to mix with air blown into air conditioned rooms or buildings. With 15 years of experience with hydrocarbons and after the installation of more than 400 units in Denmark, Norway, United Kingdom, Germany and New Zealand, the presenter concluded that it is possible to produce, install, maintain and decommission hydrocarbon units without more or bigger problems than with any other refrigerant, while at the same time realising energy savings.
Performance assessment of air conditioners with HC-290, Atul Padalkar, Sinhgad College of Engineering, India
With India having to phase out HCFC-22 by 2030 and many studies revealing the advantage of HC-290 in air conditioner and heat pumps, the paper co-authored by Padalkar looks into the use of R290 in room air conditioners. A 5.13 kW capacity split air conditioner designed for HCFC-22 was retrofitted with R290, while duly considering all safety measures, brazing all tubing joints, sealing all electrical components and fitting the room with hydrocarbon detectors.
Under the drop-in test, the cooling capacity and COP of the R290 air conditioner were 6% lower and 14% higher compared to HCFC-22, while power consumption was reduced by 17.8%. The R290 charge in terms of weight was about 50% of that of HCFC-22.
Directions for further optimisation include longer capillary, higher capacity compressor and larger condenser. Finally, Padalkar concluded that the next phase of the project will explore charge minimization through reducing the tube diameter and length of interconnecting piping and also using higher efficiency heat exchangers.
SolarChill technology - solar powered direct drive refrigerators with hydrocarbon refrigerants, Per Henrik Pedersen, Danish Technological Institute
Pedersen discussed SolarChill, the solar powered hydrocarbon based refrigeration technology developed in an international project involving Greenpeace, UNEP, the World Bank, WHO, UNICEF, GTZ, PATH, industrial partners and Danish Technological Institute (DTI). He provided the audience with the specifications of different versions of SolarChill for different applications including SolarChill-A for vaccine coolers and SolarChill-B for domestic and small business applications in areas where grid power is non-existent or unstable.
An estimated 200 SolarChill vaccine coolers have been manufactured by Vestfrost A/S and installed in many countries, while a greater deployment is expected with the involvement of the World Bank and after receiving pending approval that the product meets the new specifications by the World Health Organisation (WHO). SolarChill-B is currently being tested, with commercialisation being the next step for the SolarChill partnership.
Finally the presenter discussed future types of SolarChill, including the possibility of increasing the cooling capacity of systems through the use of compressors with higher cooling capacity and a larger photovoltaic area. DTI has been considering the development of a milk cooler for small farms, where milk has to be cooled down to about +4°C in less than 2 hours. Finally, he mentioned the possibility of developing a freezer type SolarChill for freezing and conserving fish, meat and vegetables.