Performance Investigation of An Automated Thermoelectric Refrigerator for Cooling Applications Using Constant Load

Abstract

A thermoelectric Refrigerator is a semiconductor-based electronic component that functions as a small heat compressor. This research focused on thermoelectric refrigerators that use forward biasing to improve the Coefficient of Performance. The constant cooling load was used to investigate its performance with special consideration for the fruit using apple fruit as referenced. Apple fruit thermodynamic parameters were adopted for the design calculation with 2kg (ten pieces) of apple fruits taken as specimens. Apple fruit storage temperature of – 4.4 ⁰C was considered at the design stage. The size of the cooling chamber is 0.03 m3. The designed cooling capacity is 123.7 W, while the theoretical coefficient of performance is 0.71. Peltier module of model TEC1-12705 with refrigerating power of 126W and input voltage of 12 VDC selected. Model W1209 automatics temperature controller with an output voltage of 12 VDC was used. A forward bias configuration was used to diminish the potential barrier of the electric field and allow current to flow effortlessly across the junction of the thermoelectric module. Temperature data were captured every two minutes during no-load and when the system was loaded with 2 kg of apple fruit. The performance evaluation of the system constructed recorded the practical coefficient of performance of 0.22, maximum coefficient of performance of 0.71, and cooling capacity of 29.21 W.  The lowest temperatures achieved are 19 °C without load and 22 °C with load. It was established that the temperature cannot be reduced to more than 19 °C after 56 minutes of continuous running by the system constructed. The system designed and built works satisfactorily. This work uses the specific heat capacity of the fruits to calculate the electrical variables needed to build an automation circuit. It uses forward biasing to improve the coefficient of performance of the thermoelectric refrigerator system. It was recommended that the efficiency of the thermoelectric refrigerator can be improved on if a thermoelectric module with a higher refrigerating effect could be developed as a single unit