design of a low cost absorption …ideastoimpact.net/sites/default/files/doc_research...ideas to...
TRANSCRIPT
ideas to impact.
SEPTEMBER 2017
DESIGN OF A LOW COST ABSORPTION REFRIGERATORENERGY ACCESS | LPG CYLINDER PRIZE WINNING SOLUTION (3/7)
ideas to impact.
8 LPG CYLINDER PRIZE - EVALUATION REPORT SUMMARY
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 PRIZEAs 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.
ACKNOWLEDGEMENTSThe 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.
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. In USA, there are IcyBalls that after
80 years still maintain its original mixture (The system does not require special maintenance; in
consequence it is most robust and reliable than other refrigeration systems based on
compressors and moving parts).
Of course, if the gas cylinder is corroded or in extremely bad conditions it could not be used.
However, the cylinders with leaking or damaged valves (which are not necessary for the
system), dents and the like could be safely used.
In the place of the removed valves, the U shaped steel pipe should be welded. In the patent
picture above, the U-pipe connection is different, but such connection in essence does not
affect the system’s function, the two variants are perfectly viable [see patent description 10]
[11]. Not all the parts showed in the patent are actually essential.
The inner tubes showed in the “hot vessel” of the patent picture (left vessel) and numerated as
10, 16, 15 and 13 constitute the check valve. The check valve function is to allow the pass of
gas ammonia during heating to the “cool vessel” and to bubble the ammonia inside the water
during the cooling for a better absorption, this is why we have a submerged tube 10. Without
this check valve, the IcyBall would not work properly. I have attached a simpler design and a
good explanation about the principle of operation of the check valve [12]. Of course, other
variants are possible.
About the heating sources, a simple kerosene flame is a viable solution but again, other
variants are possible. For example, one could use solar heat concentrated with lens like in
some university projects [8] or use solar panels to generate electricity for heating. When
heating it is important to control the process, the control could be done as in old IcyBalls
measuring the quantity of kerosene in the heat source (if you use kerosene) or it is possible to
install a whistle like in teakettles in order to measure the pressure inside the ball.
The details of the IcyBall design can vary a lot, thus there are many possible variants. Such
variants should be specified depending of the resources of the country in which the system is
manufactured. For example, it would be possible to look for another non-toxic refrigerant
instead of ammonia. Alternatively, it would be possible to develop another way the regenerate
the system without moving the vessels inside a water bath, which requires a certain degree of
physical strength.
The manufacturing process will require a certain degree of manual skills, but such skills can be
teach and learned by any common worker. In principle, it would be required good welding
skills and knowledge about ammonia manipulation. Such skills can be mastered by one
individual.
The basic list of materials has been explained along the submission, but in general, it would be
required water, ammonia, the retired gas cylinders, steel tubes, valves and a cabinet. A
detailed description of costs would be difficult but in USA, the price of ammonia is around 4
$/kg, the price of water could be considered free of charge, the price of gas cylinders are
assumed to be free in this situation, the piping, valves and welding would be the most
expensive and probably 50 $ as much. On the other hand, the cabinet would add some costs in
the final product.
In theory, an amateur inventor building a system like the one I described here in USA should
invest around 100 $ to 200 $. Of course, if it is possible an industrial production of millions of
fridges, the costs will be much lower.
In contrast, a pot-in-pot refrigerator in Nigeria costs around 1.30$ but its capacity for storing
food and refrigeration is much more limited. A bigger and cooler fridge will allow to increase
the food production of the farmers without spoilage problems. As well as conserve more
delicate foods like fish. In addition, this system could be used to produce ice that could have
other useful applications.
The bigger size of the system proposed holds more subtle advantages, for example like
happened in middle ages Europe, two or more families could purchase one tool in order to
divide costs, in this case, two families could share one refrigerator.
Project continuation
If this solution is selected, I would like to continue working on the project’s details. This
proposal could generate a massive impact in Sub-Saharan countries but it requires further
specification.
Checklist
Irreversibility of the new non-LPG cylinders – proposed solutions must describe a new
application that makes it impossible for defective and unsafe cylinders to be returned to use
as LPG cylinders. That is, the transformation into non-LPG cylinders must be absolute, one-
way, and irreversible. Solutions that additionally address the refurbishment of cylinders (if
any) must guarantee that the proposed solution meets safety standards, making sure that
there are no possible leakage / noncompliance.
The application is completely new, and when manufactured the gas cylinders cannot be used
again as LPG cylinders.
Value – the solution must generate a high-value application for the recycled cylinders.
Solutions that lead to high income, as long as other societal benefits (e.g. job creation,
reduction of inequalities and poverty, etc) will be preferred. At a minimum, proposed
solutions must be more cost-effective than the current solution (i.e. cleaning the cylinders
and sending them to the hydraulic press for recycling the steel).
As in the pot-in-pot fridge in Nigeria, this submission has the potential of huge economic and
social benefits.
Geographical context – the proposed solution must be adapted to the social, economic
and cultural contexts of sub-Saharan African (SSA) countries.
Yes, it is.
Environmental impact – the solution must be environmentally more sustainable than the
current solution (i.e. cleaning the cylinders and sending them to the hydraulic press for
recycling the steel)
The refrigeration system is very sustainable. In addition, some countries like Ghana use
refrigerators (when electricity allows it) based on environmentally harmful CFCs which are
banned in developed countries.
Capacity and inventory – Country A is used as an example of a target country, but
solutions should have the capacity to deal with some degree of uncertainty. With that in
mind, your solution must give an answer to the greatest part of the inventory (not specific to
a cylinder size, material...). The bigger the capacity to deal with the inventory (approximately
1.5 million old cylinders to be removed from circulation, amongst a pool of 3 million that
need to be checked for safety) the higher the solution will be rated in this requirement.
This solution could potentially deal with most of the cylinders. Millions of fridges can be
produced.
Local resources – the solution should rely on technical and human resources that are
available in SSA and use African countries equipment and labor force (nice to have).
In general, the solutions could be implemented using the resources in such countries. Of
course some skills are required by the workforce but should be learned easily.
References
[1] Creamer Media. Africa’s energy problems threatens growth, says Nepad CEO
12 November 2009
[2] Rockefeller Foundation. Waste and Spoilage in the food chain.
https://www.rockefellerfoundation.org/app/uploads/Waste-and-Spoilage-in-the-Food-
Chain.pdf
[3] https://en.wikipedia.org/wiki/Pot-in-pot_refrigerator
[4] http://www.gizmag.com/solar-powered-fridge-emily-cummins/10990/
[5] http://crosleyautoclub.com/IcyBall/crosley_icyball.html
[6] https://en.wikipedia.org/wiki/Icyball
[7] http://crosleyautoclub.com/IcyBall/IB_Manual/operations_manual.html
[8] http://www.solaripedia.com/files/1113.pdf
[9] http://crosleyicyball.com/index_files/Page1030.htm
[10] http://crosleyautoclub.com/IcyBall/IB1740737/IB1740737.html
[11] http://crosleyautoclub.com/IcyBall/IB1811523/IB1811523.html
[12] http://crosleyautoclub.com/IcyBall/HomeBuilt/HallPlans/IB_Directions.html
[email protected] @ideastoimpact
IMC Worldwide Ltd
64-68 London Road Redhill, Surrey RH1 1LG, United Kingdom
Tel: +44 (0)1737 231400
Fax: +44 (0)1737 771107
Email: [email protected]
Energy 4 Impact
Fifth Floor - Totara Park House
34-36 Gray's Inn Road
WC1X 8HR
London, United Kingdom
Tel: + 44 207 242 8602
Fax: + 44 207 242 8602
E-mail: [email protected]
© 2017 by IMC Worldwide Ltd. This work is made available under a Creative Commons Attribution 4.0 licence (International). This means that you are free to share and adapt this information for any purpose, even commercial. However, you must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. You may not apply legal terms or technological measures that legally restrict others from doing anything the licence permits.
To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/legalcode
This work was supported by the UK Department for International Development, from the UK government, and the Ideas to Impact programme managed by IMC Worldwide Ltd.