World Refrigeration Day 2023: Vaccine Fridges Powered by Solar Energy
Monday, 26 June 2023
Supporting Dulas and Polestar Cooling with compressors for solar powered vaccine fridges used in developing countries
How might refrigeration be delivered in a more sustainable way – today and in the future?Dulas developed their first solar-powered refrigerator 40 years ago and the pioneering design has been refined further ever since. Thousands of units have been produced at Polestar Cooling, the company’s manufacturing facility based in Bognor Regis, West Sussex. Key components, such as Secop compressors, are supplied by Hawco.
With ‘Next Generation Cooling’ as the theme of World Refrigeration Day this year, we wanted to celebrate the work of Dulas, a manufacturer of vaccine fridges and blood banks used in developing countries - and which are powered by renewable energy from the sun.
Each cooling unit is an essential part of delivering primary healthcare and vaccine rollouts in remote parts of the world where there is no electricity. This means storing vaccines within a limited low temperature range – otherwise vaccines lose their effectiveness. This is often a major challenge for areas with an unreliable electricity supply.
The Dulas range of Solar Direct Drive (SDD) refrigerators ensure that vaccines remain at the precise temperature required to remain viable. They are used for both routine immunisation programmes and to support humanitarian aid projects globally.
A constant internal temperature can be achieved between +2°C to +8°C, even in ambient temperatures as high as 43°C.
An energy store uses an advanced phase change material (or PCM) to maintain the required storage temperature at night or on cloudy days. This unique liquid freezes and thaws at exactly +5°C, providing an almost infinite number of cooling cycles.
The World Health Organisation (WHO) requires fridges to maintain temperature storage for three days without power supply. Dulas cooling units can provide up to 79 hours of autonomous cooling using its PCM energy store and innovative insulation to provide exceptional energy efficiency. In fact, Dulas is the only UK-based manufacturer of accredited by WHO.
Dulas cooling units use Secop BD35K DC compressors. These offer very low power consumption and are optimised for use with photovoltaic power with a wide voltage range (10 to 45VDC). They have an exceptionally low starting current and use an inverter drive, using Adaptive Energy Optimisation, to maximise efficiency. Hawco supply over 2000 R600a Secop compressors to Polestar Cooling each year.
Dulas have also developed an intelligent variable speed controller to improve performance in a wide range of solar operating conditions. This allows a single compressor to start with less than 50W of power available from the solar array. Using a standard 400W array, the refrigerator will operate with just 125W/m2 of solar radiation available. Extensive computer modelling shows that using this controller significantly extends the usability window of the refrigerators, making them much more resilient in low sun conditions.
According to UNICEF, more than 1.5 million people die annually from diseases that can be prevented by vaccination, many of them children. Just one 100 litre Dulas refrigerator has the capacity to store enough vaccines to treat 10,000+ children, so over the years these refrigerators have contributed to the health and wellbeing of millions of children.
Dulas plans to double its production of solar powered refrigeration units to meet extra demand from UN agencies, governments and charities working in Africa, Asia the Pacific Islands and Latin America. It has recently expanded its factory facilities in Bognor Regis to support faster manufacturing to meet the increased demand.
The company continues to innovate, develop and improve its products, using its engineering expertise to help bring much needed energy and better standards of living to many communities around the world.
Be Part of the Future of Renewable Cooling SystemsHow might technologies like this be developed further in the future? In what way could a reduction in carbon emissions and energy consumption be applied to other examples of cooling?
If you are a school leaver, you could be part of this future. There are 15 million people in the world who work in the refrigeration sector, some of them helping to design the next generation of cooling technologies.
Why not consider a career in the cooling industry? Learn more at www.fantasticfridges.com provided by the Institute of Refrigeration UK.
Hawco is a proud sponsor of World Refrigeration Day