Post00385 HYBRID SOLAR AND COOL IDEAS + PIS 19 October 2001
CONTENTS
1. HYBRID SOLAR ELECTRIC POWER continued
2. RE: Post00383 COOL IDEAS continued
3. THE PRODUCT INFORMATION SHEETS (PIS)
Visit the TechNet 21 Delhi meeting web pages at:
http://www.who.int/vaccines-access/index.html
Get the latest Technet21 documents at:
http://www.who.int/vaccines-
access/Vaccines/Vaccine_Cold_Chain/Technet/2001_Delhi_Technet.htm
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1. HYBRID SOLAR ELECTRIC POWER continued
In Post00382, 9 October 2001, John Lloyd, PATH/CVP asked:
"Does anyone have experience of 'hybrid' systems that run on PV panels and
batteries but which also run on grid electricity when it is available? Seems
to me that such systems might work well in areas with a bit of
electricity."
In todays posting Terry Hart, IT Power India, identifies a 5 year old
working installation and comments on projects under development.
See item 2 in this posting for a related message.
* Replies to: [[email protected]][email protected][/email] or use your reply button!
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Moderators note:
Hybrid systems are applicable to the very many rural places with locally
generated electricity that is available for a few hours or as many as 6
hours.
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From: "Terry Hart"
To: "'Technet Moderator'"
Subject: RE: Post00382 SOLAR +
Date: Wed, 10 Oct 2001
Hi John/Allan,
IT Power India has some experience, and there is one plant in Nepal at a DHQ
near to the refugee camps in Biratnagar which was financed by UNHCR 5 years
ago. The site is still function despite zero maintenance since installation.
Batteries are now tiered however.
ITPI is working with Soren Spanner at WHO/SEARO to put together a pilot
project in Sri Lanka and we are currently formulating a proposal for a
project in another country.
We have been working towards getting some pilot sites up and running for
about 1 year now (or more). Earlier delays beyond our control prevented us
from moving forward, but now the channels have cleared.
We have lots of info on modelling, hybrid mixes etc etc
Best regards
terry
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2. RE: Post00383 COOL IDEAS continued
These contributions from Ian Wyllie, SOTON, discusses solar powered
absorption refrigeration and makes some constructive suggestions on the WHO
Product Information Sheets.
Kirsten Myhr, RE/UUH, continues the discussion of COOL IDEAS from Post00383
and Post00384, by calling on a friend in a sunny place!
Contributions to: [[email protected]][email protected][/email] or use your reply button!
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From: "Ian Wyllie"
To: "Technet Moderator"
Subject: RE: Post00383 COOL IDEAS
Date: Wed, 17 Oct 2001
Dear Allan,
I read the notes on the solar absorption refrigerator with interest. I have
some comments, which may be of interest to the community. I don?t know what
the rules are on citations, copyright citations etc, so perhaps you can put
a statement with the reference ? if it is required.
SUMMARY:
Discussion of practical problems with the implementation of Solar Powered
Absorption refrigeration
Discussion of the reasons why this and other technologies have not found
broader application in the EPI family, and of the effectiveness of EPI
specifications in limiting innovation.
COOL IDEAS (POST00383)
COOLED BY THE SUN 06 Oct 01
Vaccines and medicines need to be stored in cool places-not so easy to find
In parts of the world with no access to electricity. To preserve vaccines
in hot conditions, scientists at the University of Jordan have designed a
cooling cabinet that runs on solar energy. The unit uses the familiar
ammonia absorption cycle for refrigeration-ammonia is driven out of an
aqueous solution by the Sun's heat, and is then condensed and circulated
back into solution through an evaporator. The designers particularly want
to improve healthcare for nomadic tribes.
From New Scientist magazine, vol 172 issue 2311, 06/10/2001, page 24
? Copyright New Scientist, RBI Limited 2001#
* Firstly the original paper is:
Design and performance study of a solar energy powered vaccine cabinet
M. Hammad*, S. Habali
University of Jordan, Faculty of Engineering and Technology, Amman 11942,
Jordan
In: Applied Thermal Engineering 20 (2000) 1785?1798
http://www.elsevier.com/locate/apthermeng
This journal is freely available online and anyone interested in this
development should read consider reading the original paper.
* Secondly, some comments on Absorption Refrigeration powered by solar
collectors:
1. There has been significant interest in this field for a number of years
(since at least 1986) but relatively few commercially viable systems have
been implemented in less developed areas. Why this is curious, because the
technology has the potential to be of great use in the field especially as
Hammad and Habili point out if the technology could be made truly mobile.
This leads me to consider a number of reasons why the technology has not
been more widely adopted:
A: Solar collector technology is by its nature not robust. Flat plate
collectors relatively simple, although the evacuated tube collectors used in
them are extremely fragile, but there relatively low efficiency means that
the sizes of collector field involved becomes cumbersome for even small
systems. I note that Hammad and Habili base their design on an alignable
cylindrical solar collector. This is a simple and effective system, however
the requirement for it to be correctly aligned, and for it to be regularly
realigned during the year pose training challenges more complex than those
found with PV systems.
COMMENT:
The fragility, relatively large size, and the training load associated with
solar collectors are probable significant factors in the lack of enthusiasm
for this type of technology
B: The technology of solar absorption refrigeration is an intermittent
cycle, because the power is only available during a portion of daylight
hours. Therefore the temperature control for the majority of the working
life of the system will be based on the amount of energy stored during the
operating day, which is a system variable directly proportional to
insolation. This means that a period of reduced insolation is likely to
cause a breakdown in the cold chain, because the system does not incorporate
any long term or reserve energy storage.
COMMENT:
Therefore, unless this system is placed at a site in conjunction with other
systems that are capable of providing assured refrigeration there has to be
a question over the effectiveness of service it will provide. I note that
here also there will be issues with training, because the concept of an
intermittent system does not have any analog among equipment currently in
use, indeed comparison with the existing KeroseneLPG fueled absorption
systems could cause confusion. Effective management of this type of system
requires thermodynamic understanding, which it may not be possible to
communicate effectively in the available time frame to the technicians and
healthcare workers responsible for it.
C: Consideration of the WHO EPI product testing specifications indicates
that it might be impossible to develop a solar powered absorption system
which would meet any one of the individual specifications in WH0,
WHO/EPI/LHIS/97 "EPI Equipment Performance Specifications," and therefore,
without an assured market, the likelihood of any engineering company being
willing to commit to the innovation and development required to bring such a
specialist product to market is extremely limited.
COMMENT
This is it occurs to me a more generally applicable point. EPI/LHIS/97 is
framed to produce the equipment currently approved for marketing through the
Product Information Sheets. Now, this equipment has been developed to allow
the implementation of what might be characterised as the "generic" EPI
programme customised of course to local needs. However, the recent interest
in the development of more flexible cold chain policies, and innovation in
that area is likely to result in limited change unless engineering companies
are encouraged to study product flows in the cold chain, to consult with the
user community to determine their needs, and then to produce products
meeting those needs ? even if they do not fit into the current model of cold
chain delivery.
Perhaps a set of less specific and more general specifications should be
issued covering ranges of the cold chain defined according to category ?
perhaps "outreach and health centre refrigeration" "District level, and
Hospital" and "Central Logistics Node." The specifications could state the
end outcomes required, in terms of temperature stability, volume and
robustness, without constraining innovation, in for example the integration
of power sources into a single system.
CONCLUSION
I believe that there are vital roles for solar absorption refrigeration to
play, in conjunction with other systems to allow the delivery of effective
primary health care. Personally I believe that they will be most effectively
employed in ice production at important, but possibly temporary logistic
nodes, for example during vaccination campaigns, or to support stored cold
refrigeration where there is a high density of clinics in an area lacking
infrastructure, for example an area of refugee or IDP settlement, I believe
that commercial development of the systems has been limited because of over
constraint in the drafting of specifications.
Potentially contentious thoughts? I await critical comments, contributions
or other responses with interest.
Ian Wyllie
Design Study on Medical Products Refrigeration for use in Relief and
Development Settings
Faculty of Engineering and Applied Science
University of Southampton
Southampton
SO17 1BJ
The views expressed in this e-mail are those of the author alone and not
necessarily those of the University of Southampton.
___________________________________________________________________________
From: Kirsten Myhr
To: "'Technet Moderator'"
Subject: RE: Cool ideas and Hybrid solar
Date: Thu, 18 Oct 2001 21:08:05 +0200
Allan,
I used again my source in a sunny developing country who knows quite well
power sources and options to comment on the cool idea and the hybrid solar.
Regards
Kirsten Myhr
This is his response:
HYBRID SOLAR
''Hybrid solar systems use both available sunlight and available mains
electricity to charge batteries, and can provide very reliable power under
appropriate conditions including limited hours of electricity and or
sunlight''.
By definition "mains electricity" means connected to a national grid or
small town power station - in which case solar is outlandishly expensive -
no one in their right mind would add solar power to a mains system! If
there is mains on for 8 or 12 hours a day (as in a small town / rural
community) then big batteries & a big charger is the answer - solar is
presently the most expensive form of power available (wind power is
cheaper). If one is going to install a small generator (to run 3 or 4 hours
a day) - then put in a slightly bigger one and go the route of charger and
batteries again - solar is the last option again. Please do not
misunderstand me - I would love the whole world to run on solar - it is
clean, quiet and very low maintenance but one must be realistic - it is
still too expensive - particularly in poorer rural areas.
The expense is in the capital outlay - it is easy for a first world
inhabitant to calculate that after the system has been in for 3 or 5 years
it is "free" because of almost zero maintenance but the third world person
simply can not afford it in the first place. We find it very difficult to
sell our solar water pumping systems against diesel/petrol pumps and our
clients do immediately see the long term advantages but it is only the more
affluent ones that can afford the capital outlay - so; the rich can afford
to benefit and the less fortunate just have to struggle on.
---
Does anyone have experience of 'hybrid' systems that run on PV panels and
batteries but which also run on grid electricity when it is available?
See above - "grid" electricity implies a constant supply or a big central
generator set, power station or national grid - then one would use a
suitable charger and bank of batteries - solar is not an economic option -
not even close!!!
Seems to me that such systems might work well in areas with a bit of
electricity. Point me at an area with "a bit of electricity" - you either
have it or do not have it!
''Fridges waste a lot of energy cooling down after the door has been
opened, says Hitachi of Japan. So in its latest fridge, the firm has placed
a small door within the big door for those often-taken-out items, such as
milk. In tests, the idea has cut the amount of escaping cold air by 90 per
cent, Hitachi says''.
Very true - an excellent idea !
---
COOLED BY THE SUN 06 Oct 01
''Vaccines and medicines need to be stored in cool places-not so easy to
find in parts of the world with no access to electricity. To preserve
vaccines in hot conditions, scientists at the University of Jordan have
designed a cooling cabinet that runs on solar energy. The unit uses the
familiar ammonia absorption cycle for refrigeration-ammonia is driven out
of an aqueous solution by the Sun's heat, and is then condensed and
circulated back into solution through an evaporator. The designers
particularly want to improve healthcare for nomadic tribes''.
They are dreaming again! Now - this is an application where photovoltaic
solar is the best option.
Consider the following:-
a) Absorption fridges are pathetically inefficient - even when heated by
LP gas they are not wonderful. They have to be kept exactly level
(difficult if it gets moved by nomads quite often) and rely heavily on
temperature differentials - ambient temperatures are critical. In hot
climates a water evaporation cooling system is often better. The solar heat
"gathering device" would be critical - if it is a dish or similar it would
have to be moved to follow the sun all day.....
b) A solar array filling batteries or directly driving a commercially
available 12 volt DC fridge compressor (like the Engle fridge from Japan,
the Minus 40 fridge from South Africa or several from Australia ) is a very
efficient unit that is robust and not subject to the same level
constraints, etc. Most of these units have good "hold over" capabilities to
keep contents cool over warm nights.......
The absorption may be cheaper but if it does not work - what use is cheap ?
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3. THE PRODUCT INFORMATION SHEETS (PIS)
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The Product Information Sheets (PIS), provides general information on the
choice of equipment, together with specific technical and purchasing data
for individual selected items.
Product Information Sheets, 2000 edition (WHO/V&B/00.13)
http://www.who.int/vaccines-documents/DocsPDF00/www518.pdf
This is the 12th edition of the Product Information Sheets, produced by the
WHO Expanded Programme on Immunization (a team under the Department of
Vaccines and Biologicals) in collaboration with the Supply Division of
UNICEF (Copenhagen) on a regular basis since 1979.
The PIS was formerly concerned only with equipment for the Expanded
Programme on Immunization (EPI). From the 1993/1994 edition onwards the
scope was expanded. This edition includes equipment from the programme to
reduce Acute Respiratory Infections (ARI) as well as equipment to be used in
emergency campaigns and for other primary health care initiatives.
For the EPI, this edition includes the standard selection of cold chain
equipment for the storage, transport and administration of vaccines, as well
as equipment for the collection and transport of stool specimens for the
isolation of polio virus.
A new section, Waste Disposal, has been added to this edition. This section
includes all the previously listed safety products from the section E10 on
Injection Accessory, and some new products. These products have been given
their own section in order to highlight the importance of safe injections in
immunization services, a priority project of WHO.
For the EPI equipment, standards for performance and testing of EPI
equipment are contained in a series of WHO/EPI documents, Equipment
performance specifications and test procedures. These publications which
were prepared for use by manufacturers in the international market, provide
clearly defined blueprints for the production of equipment that will meet
the highest competitive standards of reliability and performance in the EPI.
http://www.who.int/vaccines-
access/Vaccines/Vaccine_Cold_Chain/Equipment/PIS/Specs&Procs.htm
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