Aims: This study investigates the performance of a developed automated ice-cube making machine under controlled ambient conditions, in which its energy usage, rate of ice cube production and refrigeration system performance was analysed.
Study Design: Average ambient temperatures of 24°C and 32°C were considered for investigation in order to determine their influence on ice production capacity, rate of ice-cube making and energy consumption. The choice of the ambient temperature is based on the extreme ambient conditions under which the machine is designed to operate in a wide range of geographical regions. The refrigeration system performance was carried out under normal room temperature (average of 23°C).
Place and Duration of Study: Department of Mechanical Engineering, Federal University of Technology Akure, Ondo State Central Workshop, Between December 2017 and January 2018.
Methodology: The machine was set into operation for 5 consecutive ice production cycle during which the ice making time, harvest time, quantity of ice produced and energy consumption were recorded.
Results: The ice production capacity, harvesting time and energy consumption show various dissimilarities at both temperatures. 0.618 kg of ice cubes were produced within an ice making cycle of 34.9 minutes, harvesting time of 1.28 minutes and total energy consumption of 0.14053 kWh at 24°C while at 32°C, the machine produced an average of 0.612 kg ice cubes within an ice making cycle of 38.5 minutes harvesting time 1.21 minutes and energy consumption of 0.15947 kWh respectively. Consequently, 13.5% more energy is consumed, with about 1% less quantity of ice produced at 32°C than at 24°C per ice production cycle.
Conclusion: Therefore, the ice making capacity of the developed machine suggests that the temperature of the environment has a strong influence on the energy consumption, but little effect on the quantity of ice produced per cycle. The refrigeration system cycle performance analysis results showed a considerably high cooling capacity of 0.379 kW during the ice-making cycle with a corresponding coefficient of performance (COP) of 2.23, and a heating capacity of 2.24 kW during the harvest cycle with a corresponding COP of 8.21. The results obtained showed that the machine is reliable in operation with minimal energy consumption.
Experimental evaluation on the use of capillary tube and thermostatic expansion valve with heat recovery hot spot water heater in air source refrigeration system
