SOLAR – ELECTRIC SYNERGY UNIT FOR PRODUCTION OF DAHI AND YOGURT
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Date
2023
Authors
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Journal ISSN
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Publisher
ICAR-NDRI, KARNAL
Abstract
A low-cost batch fermentation unit for dahi and yogurt production was developed, utilizing
renewable solar energy as the primary source of heating. The unit incorporated a hybrid system with
an electric heater and phase change material (PCM) based heating. It consisted of a solar flat plate
collector (FPC) with optional PCM containers, an electric heater and blower assembly, a
fermentation cabinet with trays, and an evaporative cooling system. The system efficiently utilized
outgoing hot air from the fermentation cabinet by connecting a recirculation pipe to the solar
collector's air inlet. During sunshine hours, the collector absorbed heat, and the air passing through
it was blown into the cabinet, maintaining a desired temperature. In the absence of sunlight, the
hybrid heating system was employed. Computational fluid dynamics (CFD) simulations were
conducted to analyse temperature distribution and airflow inside the fermentation cabinet,
validating the results against experimental data. The system's performance was evaluated through
experiments, demonstrating its ability to produce quality dahi and yogurt. The trials were conducted
at different air velocities, with faster temperature rise observed at higher velocities. The optimal
electrical wattage for heating was determined, and paraffin wax served as the PCM for thermal
energy storage. The developed system achieved effective cup pre-cooling with varying air
velocities. During summer, a significant temperature drop of 16 ℃ was achieved, while in peak
winter, cups were cooled to 5.5 ℃. Comparative analyses showed no significant differences in
product quality between the developed system and the conventional method. Energy consumption
was a crucial consideration, with the solar system exhibiting significantly lower power consumption
compared to the conventional electrical unit. Overall, the developed fermentation unit utilizing solar
energy as the primary heating source demonstrated efficient performance, cost-effectiveness, and
excellent product quality to conventional methods.