ideasideas to to impact. impact. DESIGN OF A LOW COST ABSORPTION REFRIGERATOR ENERGY ACCESS | LPG CYLINDER PRIZE WINNING SOLUTION (3/7) SEPTEMBER 2017 ABOUT IDEAS TO IMPACT Ideas to Impact is an action-research programme designing, implementing and testing innovation prizes, to induce innovative solutions to development challenges in Climate Change Adaptation, Energy Access and WASH. A five year, £10.9m programme, funded by the Department for International Development (Dfid) that supports research and development in climate change, energy and WASH through a variety of innovation prizes. The prizes are designed to stimulate and incentivise development of technologies for low income consumers that will improve poor people’s access to affordable clean energy, safe drinking water and resilience to climate change. ABOUT THE ENERGY ACCESS: LPG CYLINDER PRIZE As part of the Ideas to Impact the Energy Access: LPG Cylinder Prize launched on July 7, 2015, focused on inducing innovations for recycling liquid petroleum gas (LPG) cylinders across sub- Saharan Africa. Applications were received from more than 180 solvers, from over 40 countries, proposing solutions to address the problem of how to maximise the value of large numbers of aging and unsafe LPG cylinders that might need to be retired in the event of market reforms. No readily available solution which could be implemented at scale was identified. However, seven winners were selected, who offered solutions which in the view of the judges had potential to address the challenge subject to further research and development. Here we share one of these winning solutions. ACKNOWLEDGEMENTS The Energy Access prize is led by Simon Collings at Energy 4 Impact, and collaboratively designed with Jonathan Slater from The Blue Globe. Ideas to Impact is managed by IMC Worldwide Ltd. With special thanks to the independent panel of judges who judged the winning solution. 8 LPG CYLINDER PRIZE - EVALUATION REPORT SUMMARY Novel uses for removed gas cylinders: Design of a low cost absorption refrigerator The need for low cost absorption refrigerators in Sub-Saharan Africa countries Fifty percent of Africa is rural with no access to electricity. Africa generates 47 GW of electricity, less than 0.6% of the global market share. Many Sub-Saharan countries are affected by power shortages [1]. The lack of electricity or its low reliability impedes the conservation of food for long periods, thus fresh or perishable food like fruits, meat, fish or many vegetables need to be eaten immediately, or it will go to waste, or cause serious risks for human health. The main problem is stated very clear but its consequences are huger. The Rockefeller Foundation analysed in a 2013 report [2] the spoilage of food that affects all the chain from the farm, markets to homes, causing loss of incomes for farmers and shortcomings in food supply. Therefore, the means for food conservation are critical and represent a massive effect on economies as well as an improvement of public health and food accessibility. Let us analyse the current solutions proposed by other inventors and entrepreneurs. The Rolex awards gave a prize to the Nigerian teacher Mohammed Bah Abba in 2001, for the invention of an evaporator refrigeration system called pot-in-pot refrigerator. Pot-in-pot refrigerator Source: Wikipedia The working principle of such kind of refrigerators are explained in Wikipedia [3] but basically it is a system formed by two ceramic pots which includes sand and water between. The evaporation of water draws the heat from the inner pot. Abba’s invention generated huge positive additional effects on the rural Nigerian population: . Increased profits from food sales: As there is no rush to sell food to avoid spoilage, farmers are able to sell their produce on demand and can command higher prices. Increased opportunities for women: Women can sell food directly from their homes, decreasing their dependence on their husbands as sole providers. Also, because girls traditionally take food to market to sell, and because food in the refrigerator stays fresh long enough that they can go to market once a week rather than once a day, there is more time for them to attend school. Rural employment opportunities: Farmers are able to support themselves with their increased profits at market, slowing the move into cities. In addition, the creation of the pots themselves generates job opportunities. Increased diet variety: Food is available for longer into the year. Others: The ability to store vaccines and medicines that would otherwise be unavailable in areas without refrigeration facilities Another awarded inventor from United Kingdom, Emily Cummins developed in 2009 the same concept but with a little more sophistication [4]. Emily Cummins’ concept Although Mohammed and Emily’s refrigerators generated important advances in Nigeria and Namibia respectively, their inventions have very limited refrigerating capacities as well as little food storage potential. In particular, Emily’s invention seems to be better suited for transporting vaccines and/or medicines than for food storage. On the other hand, the two inventions have a difficult practical use because the inventions do not allow the organization of contained food. Therefore, if one needs to extract a tomato from the bottom of the fridge, he or she must first extract the upper vegetables. In addition, the weight of the vegetables can crush the bottom vegetables and this is not convenient. I propose to develop a new design for a refrigerator which can be build using the retired gas cylinders and that will allow increased cooling capacities and a better capacity and organization for food storage. Low cost absorption refrigerator Two vessels and two liquids integrate the most basic variant of absorption refrigerator, one liquid is a refrigerant with a low boiling point and the other is the absorbent in which the refrigerant can be dissolved. The most basic absorption refrigerator was known as IcyBall [5][6], and widely used in the old rural America (1920 - 1940) without electricity supply. Some of the original 80 years old IcyBalls are still being used by amateur collectors and nostalgic people demonstrating its fully functionality, which means it is a robust and reliable system. I have attached the link of a user manual from its old manufacturer [7]. US patent 1740737 (1929) IcyBall refrigerating a container with food The principle of operation is very simple; there are two vessels, the “hot vessel” and the “cold vessel”, communicated by a U shape pipe. In the “hot vessel”, there is an initial mixture of water and ammonia, the “cold vessel”, in principle, should not contain anything. For starting its operation, the “cold vessel” is externally submerged in water while the “hot vessel” containing the mixture of water and ammonia is slightly heated. As the temperature rises in the “hot vessel”, the solubility of ammonia in water decreases, the pressure raises and therefore the ammonia boils and pass through the U shape pipe to the “cold vessel” that is externally submerged in water. As a result, the ammonia is condensed inside the “cold vessel”. When the “cold vessel” is fully charged with liquid ammonia, the device is turned around, placing the “hot vessel” in the water bath. As the “hot vessel” cools, the pressure in the system falls, eventually dropping to the point where the liquid ammonia in the “cold vessel” begins to evaporate, thus, the ammonia returns through the U shaped pipe to the water, and in consequence, the “cold vessel” begins to freeze. Finally, the IcyBall is just placed into a cabined for food refrigeration as showed in the picture above. The system provides refrigeration for approximately one day until the heating process described is repeated again. In average, an IcyBall using ball shaped vessels of approximately 20 centimetres of diameter, filled with the mixture in a proportion of 57.2% in weight of water and 42.8% in weight of ammonia, should be able to provide a temperature range of 2 to 8 °C in a (approximately) 70 x 40 x 90 centimetres cabinet for at least 24 hours. Constructive details Before starting with the explanation of the constructive details, it is important to prove that it is possible to build a homemade modern IcyBall using old gas cylinders. According the compatibility tables developed by Air Liquide Corporation, the water – ammonia mixture could be contained in vessels made of aluminium, steels (ferritic, carbon, stainless…) and the plastics PTFE, PCTFE, NYLON, EPDM, PP and IIR without problematic consequences [8]. A quick search reveals that in fact, some inventors built homemade IcyBalls using old propane cylinders in combination with fire extinguishers [9]. In principle, and according the challenge details, such gas cylinders are made of special alloy steel, which means it is a viable vessel for using ammonia. Another feature of the tanks described in the challenge is that they are designed at 34 bar of top pressure that is far enough for our purposes. An IcyBall based on water – ammonia when heated correctly should produce maximum pressures in the range of 14 – 17 bars. The photo is a home built IcyBall built by an inventor of Florida out of an old propane tank and fire extinguisher for less than $100 As you can see, the basic design is simple. The system should include two vessels made of the removed gas cylinders of a similar size (Or one gas cylinder and another kind of vessel). The upper valve of the gas cylinder is then removed; one of the cylinders should be filled with the mixture water and ammonia. The filling process should proceed carefully because ammonia is a toxic gas. However once the ammonia is properly sealed inside the system, the risks for the users should be similar or lower than the risk in some refrigeration systems in a developed country like USA or Canada or any other country in Europe.