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A solar assisted high temperature refrigeration system for postharvest pre-storage fruit cooling
Author(s)
Alkilani, Fouad M.
Date Issued
2017
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Agriculture has emerged as a major economic activity in the African continent.
Therefore, fruits and vegetables are considered as essential source of vitamins,
minerals and proteins. However, fruits and vegetables are perishing rapidly. Thus, the
adequate handling starts from the field, by applying appropriate method of storage
and preservation in order to reduce post-harvest losses and extend its shelf life.
Preservation by removing heat from the products is the most common method of
preservation. In rural areas, the access to the grid is expensive or in some cases
impossible. Therefore, researchers have been paying more attention to find
alternative sources of power to run the cooling units.
This study provides proof of a concept for the use of solar energy to cool down
harvested fruits and vegetables at the farm level to an adequate farm storage
temperature. The target storage temperature range is between 5 and 15 oC. A model
refrigerator was designed and constructed in the mechanical engineering workshop of
Cape Peninsula University of Technology. It was installed and tested in outdoor
conditions to get the effect of different weather conditions. The model consists of a
typical vapour compression system powered by a 12 V solar PV system. A DC
compressor was used, and therefore, there is no inverter. The model was first tested
without a product and then with 20 kg batches of different fruits for a period of two
weeks in April 2016. Wind speed, ambient temperature and solar radiation intensity
data were monitored and collected from a Campbell Scientific weather station
mounted on the roof adjacent to the model. By monitoring the temperatures and
compressor current hourly, the refrigeration effect, power consumption and coefficient
of performance were determined. The overall COP based on input solar energy was
2.8. It was thus proved that a suitably sized PV system could be designed and
implemented at farm level to cool harvested fruits from ambient to storage
temperature without the use of an inverter. This could go some way to helping retard
deterioration of fruits and vegetables before delivery to a marketplace or to storage.
Therefore, fruits and vegetables are considered as essential source of vitamins,
minerals and proteins. However, fruits and vegetables are perishing rapidly. Thus, the
adequate handling starts from the field, by applying appropriate method of storage
and preservation in order to reduce post-harvest losses and extend its shelf life.
Preservation by removing heat from the products is the most common method of
preservation. In rural areas, the access to the grid is expensive or in some cases
impossible. Therefore, researchers have been paying more attention to find
alternative sources of power to run the cooling units.
This study provides proof of a concept for the use of solar energy to cool down
harvested fruits and vegetables at the farm level to an adequate farm storage
temperature. The target storage temperature range is between 5 and 15 oC. A model
refrigerator was designed and constructed in the mechanical engineering workshop of
Cape Peninsula University of Technology. It was installed and tested in outdoor
conditions to get the effect of different weather conditions. The model consists of a
typical vapour compression system powered by a 12 V solar PV system. A DC
compressor was used, and therefore, there is no inverter. The model was first tested
without a product and then with 20 kg batches of different fruits for a period of two
weeks in April 2016. Wind speed, ambient temperature and solar radiation intensity
data were monitored and collected from a Campbell Scientific weather station
mounted on the roof adjacent to the model. By monitoring the temperatures and
compressor current hourly, the refrigeration effect, power consumption and coefficient
of performance were determined. The overall COP based on input solar energy was
2.8. It was thus proved that a suitably sized PV system could be designed and
implemented at farm level to cool harvested fruits from ambient to storage
temperature without the use of an inverter. This could go some way to helping retard
deterioration of fruits and vegetables before delivery to a marketplace or to storage.
Additional information
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.
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214268756-Alkilani-Fouad M-M.Eng-Mechanical-Engineering-Eng-2017.pdf
Description
Thesis
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3.66 MB
Format
Adobe PDF
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