Refrigeration for developing countries
Practical Action
Solar refrigeration units of this kind, especially designed for vaccine preservation, are
commercially available. A system providing 60-80 watts of cooling is typically priced in the
range of £3000-5500. Replacement parts will tend to cost £500-1000 in the course of four
years of operation. Most of this cost will be in the replacement of batteries which are
designed to have a four year life but can fail in a shorter period if maintained poorly.
Replacement costs are considerably reduced if skilled, technical maintenance personnel are
available.
Combined heating/drying/cooling system
Because a refrigerator releases heat it can be used to raise temperatures in agricultural
processes like crop or spice drying. The cooling effect can be used to dehumidify the air
passing over the crop and the heating effect can be used to warm the air. In this, very high
efficiencies can be obtained (for instance up to 7 times as much useful energy produced as
required to drive the device). Such efficiencies are commonly met in timber drying plants
using these principles. Practical Action is developing low cost methods of utilizing this effect,
with respect to drives from small hydro turbines or from steam or diesel engines.
A second example is the use of heat from a refrigerator (also known as a heat pump, exactly
the same machine) to help sterilize milk, while the same refrigerator cools the milk to
preserve it.
Choosing the system
In order to decide which refrigeration system to adopt for a particular purpose, it is necessary
to consider the ongoing inputs required by each system. Table 1 lists the various systems and
the inputs required for each. The choice of system is based on the foreknowledge that all the
necessary inputs will continue to be available in the locality of the fridge. The mistake is
often made of installing a unit with a relatively low purchase cost which later ceases to
function through lack of necessary inputs.
COMMENT
ENERGY SOURCE
PERSONNEL
SPARE
PARTS
10 YEAR
TOTAL COST
MECHANICAL
COMPRESSION
Grid
Electricity
Grid electricity. Cost Maintenance:
Source of
Purchase
available for other of connecting/
skilled
parts may be cost,
purposes, e.g.
transforming can be personnel.
distant.
electricity,
lighting, flaking of high.
Supply may
personnel,
ice. be uncertain. replacement
parts.
Diesel
Electricity
available for other
purposes, e.g.
lighting, flaking of
ice.
Diesel generator
Maintenance:
skilled
personnel
permanently on-
site.
Source of
parts may be
distant.
Supply may
be uncertain.
Purchase
cost, diesel,
replacement
parts.
Solar photovoltaic
Expensive.
Electricity
available for
lighting,
communications,
temperature
control.
Irradiation of 10-20
MJ/day/m². Long
cloudy periods
problematic.
Skilled
personnel
permanently
available.
Battery life 2-
4 years.
Control
electronics
can fail.
£3500-6500
for 60-80 W
cooling,
includes
replacement
costs.
SORPTION
(HDCs)
Conventional
5
Well known in the
field.
Gas/kerosene
quality must be
adequate.
Burner parts,
wick
adjustment, etc.
Replacement
of burner
parts routine.
£1000-2000
for 60-100 W
cooling and
small
maintenance
cost.