Experimental Investigation and 4E+Q (Energy, Exergy, Economic, Environmental, and Quality) Analysis of a Novel Solar Evacuated Tube Dryer

• 4E + Q analysis assessed both technical feasibility and practical viability. • Maximum collector efficiency of 49.59 % was achieved for the MFR of 0.018 kg/s. • Maximum drying rate of 0.56 kg/hr was achieved by MMSD for 0.018 kg/s MFR. • Using MMSD, energy used for dryer fabrication can be recovered in 2.99 years. • Mixed-mode type of drying demonstrated superior performance. Achieving zero-carbon emissions in the drying process requires the development of sustainable dryers powered by renewable energy sources, like solar energy, as it reduces post-harvest losses and extends the shelf life of the perishables. This study presents a comprehensive analysis of a novel solar evacuated tube dryer across five key parameters, such as energy, exergy, environmental, economics, and quality. The dryer’s performance was examined using carrot slices with an initial moisture content of 90.14% (wet basis) under three different configurations: direct solar drying (DSD), indirect solar drying (IDSD), and mixed-mode solar drying (MMSD), at varying mass flow rates (MFR) of 0.007, 0.015, and 0.018 kg/s and were compared with the open sun drying (OSD). Under MMSD-3, moisture content was reduced to 8.81% with a drying duration of 9 h which is half the time of OSD. The maximum collector’s energy (49.59%) and exergy (12.11%) efficiency was achieved at 0.018 kg/s. In terms of dryer efficiency, MMSD outperformed IDSD and DSD, attaining efficiencies of 47.33%, 38.61%, and 26.41% for different MFRs. Furthermore, the sustainability analysis shows a CO 2 mitigation potential of 17.274, 22.344, and 29.161 tons for the DSD, IDSD, and MMSD respectively. Payback periods were 0.976, 1.255, and 1.380 years for MMSD, IDSD, and DSD, confirming economic viability. The proximate analysis produced better protein, and fibre content in the MMSD than others. Additionally, bioavailable nutrients are rich in MMSD and OSD. Eventually, MMSD exhibited superior performance and shows potential for small-scale drying, offering opportunities for farmers and emerging agri-entrepreneurs.