Abstract:
A portable self-contained automated ice-cube making machine suitable for small scale ice cube production has been designed, fabricated and evaluated in this research. The machine was designed using the principle of vapour compression refrigeration system to produce 24 cubes of ice measuring 22×22×22 mm at −15 ℃ from 7.667×10−4 m3of water within 30 minutes. The machine was designed using: a R-134a reciprocating type compressor of 0.086 kW capacity; a bare tube evaporator designed for 0.2984 kW refrigeration load; a finned-tube type condenser with 0.3847 kW capacity; and a water circulation pump of 0.279 ×10−3 kW pump power. The process of feeding water into the machine and harvesting of ice cubes was automated through the application of an electronic control system incorporating a PIC16F877A microcontroller. The control unit was designed and simulated on Proteus Design Suite while the programming codes was written in C language on MPLAB IDE. The developed machine produced an average of 0.618 kg ice cubes per production cycle at −4.9 ℃ with an average ice-making time, harvesting time and energy consumption of 34.9 minutes, 1.28 minutes and 0.14053 kWh respectively, while the average ambient temperature remains at 24 ℃. The daily ice production capacity was estimated to be 24.6 kg. The refrigeration system cycle performance analysis results showed; a 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. A comparison of the estimated price for procuring the developed machine when commercialized with each of the three available imported ice makers (Ensure 94015, Mr Freeze MIM-88 and New Air AI-100R) was made on the basis of ice making capacity (kg/day). The developed machine cost less at the local production cost of ₦111,471 and production rate of 24.6 kg/day as compared to the three imported ice makers which cost ₦150,670,₦123,444 and ₦102,812 respectively with daily ice production capacity of 20,15 and 12 kg.
