Refrigeration for developing countries
Practical Action
Several approaches, which can be considered, are:
• Production of ice using electricity in regional centres; transport of this ice to
agricultural areas; packing of produce to be cooled with ice in insulated containers.
Electricity is either grid or diesel generated. Refrigerators, which are electrically
driven, use mechanical compression technology.
• In some cases refrigerators can be driven directly by mechanical shaft power, for
instance where water turbines can be readily installed.
• Production of ice using heat driven coolers ('HDCs') on a local level at agricultural
production points. Packing of produce with ice for transport. The heat sources for
HDCs are varied; it can be from wood, charcoal or agro-waste burnt in open stoves,
from fossil fuel in conventional burners, or it can be from thermal solar collectors.
HDCs use sorption technology.
• Provision of cold storage chambers using either passive, sorption, or mechanical
compression technology. If passive cooling is used, temperatures less than 10°C can
rarely be achieved.
• Provision of cold storage at the point of use using mechanical compression coolers
drawing electricity from photovoltaic cells. This is referred to as photovoltaic cooling
technology.
The most suitable method of cooling chosen will depend upon various factors; the
application, the degree of reliability required, the supply of power, the level of skill needed to
operate and maintain, training facilities, and available finance. The different technologies
should be considered with these factors in mind. As with any technology, sufficient training is
especially important; it must be planned as an integral part of an implementation programme
and remains a constant concern during
the years following installation. This will
increase reliability of the system and
Time in days
400
reduce life cycle costs dramatically.
Temperatures and ventilation
Different applications have different
230000
100
requirements for temperature control
and ventilation. Figure 2 shows the
temperatures needed for the storage of
butter, meat, fresh fish and milk. Very
often storage of vegetables is
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40
30 Butter
50
Meat
complicated by the need for careful
ventilation to remove unwanted gases,
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and to avoid humidity conditions, which
would spoil the produce. Relative
humidity requirements vary depending
on the moisture content of the produce.
5
4
3
2
Fresh Fish
Milk
A simple method of increasing humidity
is to sprinkle water on the floor. In
1
+20
+10 0
-10 -20
-30
vaccine and blood storage very careful
Temperatures (°C)
temperature control is required.
Figure 2: Temperatures for safe storage
Passive / evaporative
In applications where temperatures between 10-25°C are needed, passive methods can be
used, see Evaporative Cooling Practical Action Technical Brief. These include traditional
methods such as the use of porous jars or wet sack coverings, where the evaporative heat of
the liquid, usually water, is drawn into the atmosphere. This method is effective where the
atmosphere is naturally dry. Domestic storage devices have been designed along these lines,
particularly with the use of charcoal beds, drip-fed with water.
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