Energetic and exergetic thermal analysis of an inline-airflow solar hybrid dryer

• Published in: Applied thermal engineering 2020-02, Vol.166, p.114632, Article 114632
• Main Authors: Amjad, Waseem, Ali Gilani, Gohar, Munir, Anjum, Asghar, Furqan, Ali, Azhar, Waseem, Muhammad
• Format: Article
• Language: English
• Subjects: Air flow; Batch dryer; Design optimization; Drying; Energy consumption; Energy utilization; Evacuated tube collector; Evaporation rate; Exergy; Green chili; Heat exchangers; Heat transfer; Heating; Materials handling; Peppers; Photovoltaic cells; Solar energy; Thermal analysis; Thermal energy
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2019.114632

•Thermal analysis of solar hybrid dryer was performed under three modes of heating.•Energy and exergy efficiencies found in the range of 56–60% and 69–74% respectively.•Heating component possessed higher exergetic factor and improvement potential rate.•Comparatively 18% less specific energy (evaporation & product) used in solar mode. Uniform air distribution inside drying chamber is key factor to reduce energy consumption along with drying uniformity. A detailed thermal analysis (energy and exergy based) was performed for a newly developed inline-airflow solar hybrid dryer (coupled with solar evacuated tube collector and gas burner). The experiments were performed using green chilies at 60 °C under three modes of heating sources i.e. dual (gas + solar), gas and solar. Thermal analysis revealed that energy utilization varied in the ranges of 0–17 kJ/sec (dual), 0–16 kJ/sec (gas), 0–13 kJ/sec (solar), energy utilization ratios were in the ranges of 0–56.8% (dual), 0–60% (gas), 0–47.8% (solar) while values of exergy losses were 2.26–5.41 kJ/kg (dual), 2.45–5.56 kJ/kg (gas) 1.48–4.00 kJ/kg (solar), and exergy efficiencies were in the ranges of 33.95–74.11% (dual), 24–73.58% (gas),17–69% (solar). Heating component that comprised of heat exchanger–evacuated tube collector handled major part of energy possessing higher exergetic factor (54.37) and improvement potential rate (2.016). The values of specific evaporation and product energies were calculated 5.16, 5.77, 4.45 MJ/kg and 22.28, 24.90, 19.19 MJ/kg for dual, gas and solar modes of heating respectively. The study provides a detailed and sequential procedure to conduct thermal analysis of an industrial drying unit employing hybrid source of heating for design assessment and optimization.