Testing of a novel convex-type solar absorber drying chamber in dehumidification process of municipal sewage sludge

Each day high portion of municipal wastewater sludge is generated in cities and developing a suitable and environmentally friendly treatment technique for municipal wastewater is required. Providing a cost-effective and suitable way for sewage sludge refinement with the purpose of reducing environ-mental impacts or reutilization of sewage sludge can be an important issue for researchers. In the present study, a novel convex-type solar absorber assisted dryer has been designed for drying municipal sewage sludge. In the experimental setup, an unglazed single-pass solar air collector has been used as main air heater and integrated to the drying conventional and modified drying chambers. Experimental and CFD simulation have been used to investigate the performance of fabricated solar energy assisted dryers. Also, the effectiveness of the developed system has been analyzed in various conditions to clarify the potential of fabricated dryers. According to the results utilizing convex solar absorber led to provide high air flow rate with high temperature inside the drying chamber and consequently shortened the drying time. Experimentally obtained average energy efficiency of the modified and conventional indirect solar drying system were in the range of 32.85-47.09% and 21.32-30.45%, respectively. Moreover, the experimental results collected from CSD (conventional solar dryer) and CSASD (solar dryer with convex solar absorber) are also discussed in terms of R-2, RMSE, RRMSE, MBE, and MAPE, and a very satisfying correlation be-tween the systems CSD and CSASD is noticed with the statistical metrics. The findings of the present study demonstrate the potential of utilizing the designed dryers in drying municipal wastewater sludge. (C) 2020 Elsevier Ltd. All rights reserved.