ICR2019: focus on innovative refrigeration technologies for developing countries

Several papers presented during the IIR International Congress of Refrigeration in August 2019 addressed advances in the refrigeration technologies that are particularly adapted to hot countries with limited electricity supply: solar refrigeration, energy storage and PCMs as well as sorption technologies.

Although data from the World Bank show that there has been a considerable improvement over the last 25 years, nearly 1 billion people worldwide do not yet have access to electricity. (1)

The countries with the least access to electricity are located mainly in Sub-Saharan Africa, the Caribbean, Southeast Asia and the Pacific, and in numerous small islands worldwide. However, these regions most often benefit from abundant sunshine that can be exploited for the operation of solar refrigeration equipment. Moreover, phase-change materials and more generally energy storage can be used to store the cold produced and allow its use in adequacy with the needs.

Several papers presented at ICR2019 have focused on the progress of refrigeration technologies adapted to developing countries.

Regarding refrigerated transport, Guanghai Liu et al. stress in their paper the low number of refrigerated vehicles in developing countries compared to developed countries (eg 1/10,000 in China vs 14/10,000 in the UK) mainly due to the high initial and operating cost of refrigerated transport vehicles. These researchers have designed a novel PCM pallet which enables the use of cheap electricity at night to store energy, instead of using diesel fuel from a refrigerated vehicle. When in use, the PCM in the pallet can be frozen by the refrigeration system of a cold store. In transportation and distribution, food is stored on the PCM pallet in a thermal insulation vehicle that does not require refrigeration. (2)

Another paper by A. Coca-Ortegon et al. (3) examines solar-powered refrigerators as a useful solution for food preservation in isolated regions where there is no electricity supply or where there are frequent power outages. It evaluates in two locations – Kenya and Cuba – the energy autonomy of a solar-powered refrigerator with a PCM slab located on the internal wall of the refrigerator, in contact with the evaporator. The autonomy of the system was optimized by using a PCM slab thickness of 80mm and 100mm, and with multi-crystalline PV modules of 100 Wp and 150 Wp for Kenya and Cuba respectively, which allows the solar-powered refrigerator to be operated without an electrical battery.

Three other papers address the problem of cooling and storage of vaccines in developing countries. WHO and UNICEF (4) have highlighted that in 2014, 20% of health facilities in low- and lower-middle-income countries did not have any cold chain equipment to store vaccines and protect them against heat damage. Of the 80% equipped health facilities, only 2% had a functional cold chain that used optimal technologies. The remaining 78% of facilities were equipped with cold chain equipment that was either not functional or that used obsolete technology, putting vaccines at risk of temperature damage.

As stressed by P. H. Pedersen et al. (5), in areas without grid electricity, photovoltaic power has been used for many years for vaccine refrigerators with a lead-acid battery to store electric energy and to supply starting current for the compressor. The problem with this technology is that the lifetime of the battery is short due to deep discharging during periods with low irradiance and high ambient temperature. The development of solar “direct drive” refrigerators, where the energy is stored in ice instead of a battery, started in 1999 at Danish Technological Institute. It has been demonstrated that the energy density of ice produced by a compressor is at the same magnitude as the lead-acid battery. To date, 40 direct drive vaccine coolers from eight different manufacturers are listed on the WHO website, with the technology being one of the fastest growing technologies in the vaccine cold chain.

In their paper (6), J. K. Jensen et al. investigate through a dynamic model how different parameters related to an icelined solar powered vaccine cooler affect its autonomy. The results show that the mass of ice in the storage was the most promising parameter to consider for prolonging the autonomy. Furthermore, it was shown that reduction of the thermal bridges in the cabinet also was of great importance. (26254).

Finally, R. Kühn et al. (7) have presented the first results of a novel solar heat driven off-grid medical refrigerator from field-testing. The refrigerator is cooled by a miniature adsorption cycle, designed to run without any electricity. It is powered by hot water heated by a standard solar thermal collector, unlike other solar off-grid adsorption refrigerators. Water is used as the refrigerant. The refrigerator compartment temperature needs to stay within 2 to 8 °C at ambient temperatures of up to 32 °C to satisfy the WHO requirements for off-grid vaccine refrigerators in temperate climates. This goal has not been fully achieved. However, easy-to-implement measures for improvement were identified and will be conducted to ensure sufficient performance of new prototypes.

All these papers are available in the Fridoc database (see links below).

All the other communications of the Montreal congress can be downloaded here: https://bit.ly/2KKdQot

IIR members benefit from a quota of free downloads.

(1) International Energy Agency, 2018. World Energy Outlook 2018: https://www.iea.org/weo2018/

(2) Guanghai Liu, Junzhang Wu, Ruhe Xie, Judith Evans, Alan Foster, Design and application of a novel cold chain pallet using a phase change material: https://bit.ly/34lzA1T

(3) Adriana Coca-Ortegon, Juan Prieto, Alberto Coronas, Sizing of thermal energy storage with phase change materials for a battery-free solar-powered refrigerator: https://bit.ly/2qAYsnt

(4) WHO-UNICEF joint statement, Achieving immunization targets with the comprehensive effective vaccine management (EVM) framework: https://bit.ly/2Oy9mCx

(5) Per Henrik Pedersen, Ivan Katic, Jonas Kjær Jensen, Wiebke Brix Markussen, Hendrik Moeller, Claus Cording, Direct drive solar coolers: https://bit.ly/2D5QzsL

(6) Jonas K. Jensen, Christoffer Busk, Claus Cording, Per Henrik Pedersen, Wiebke B. Markussen, Extending the autonomy time of an icelined solar powered vaccine cooler: https://bit.ly/34bzycz

(7) Roland Kühn, Kilian Mähne, Karsten Düwell, Christoph Göller, Julia Römer, First field test results of a solar thermal off-grid refrigerator for vaccines: https://bit.ly/2ODwNKr