Energy and exergy analysis of an indirect solar cabinet dryer based on mathematical modeling results

In the present study, using a previously developed dynamic mathematical model for performance analysis of an indirect cabinet solar dryer [1], a microscopic energy and exergy analysis for an indirect solar cabinet dryer is carried out. To this end, appropriate energy and exergy models are developed and using the predicted values for temperature and enthalpy of gas stream and the temperature, enthalpy and moisture content of the drying solid, the energy and exergy efficiencies are estimated. The validity of the model for predicting variations in gas and solid characteristics along the time and the length of the solar collector and/or dryer length was examined against some existing experimental data. The results show that in spite of high energy efficiency, the indirect solar cabinet dryer has relatively low exergy efficiency. Results show that the maximum exergy losses are in midday. Also the minimums of total exergy efficiency are 32.3% and 47.2% on the first and second days, respectively. Furthermore, the effect of some operating parameters, including length of the collector, its surface, and air flow rate was investigated on the exergy destruction and efficiency.

► In the literature, there are few studies on the energy and exergy analysis of solar cabinet dryers.
► In the present study a microscopic energy and exergy analysis for an indirect solar cabinet dryer is carried out.
► Effect of operating parameters, including collector length, and air flow rate was investigated on the exergy destruction and efficiency.
► For collector section, the maximum values for outlet air temperature, outlet exergy and energy are 69 °C, 2.5 kW and 1.12 kW, respectively.
► Increasing the air flow rate decreases the exergy efficiency of solar collector.