EXPERIMENTAL INVESTIGATION of an INTEGRATED SOLAR DRIVEN WASTEWATER TREATMENT SYSTEM for TRIGENERATION APPLICATIONS by MURAT
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EXPERIMENTAL INVESTIGATION OF AN INTEGRATED SOLAR DRIVEN WASTEWATER TREATMENT SYSTEM FOR TRIGENERATION APPLICATIONS By MURAT EMRE DEMIR A Thesis Submitted in Partial Fulfillment of the Requirement for the Degree of Doctor of Philosophy in Mechanical Engineering University of Ontario Institute of Technology Faculty of Engineering and Applied Science Oshawa, Ontario, Canada August 2018 © Murat Emre Demir, 2018 ABSTRACT Hydrogen is a promising alternative as an energy carrier (and carbon-free fuel) to meet the global power demand. Hydrogen production systems can efficiently harvest energy from renewable sources. Even though photo-electrochemical systems offer an attractive potential for both hydrogen production and wastewater treatment systems, their application in industrial scales is not satisfactory. This thesis study proposes a trigeneration system for electricity, hydrogen and clean water production. TiO2 photocatalyst is used in a photoelectrochemical (PEC) reactor, which cleans the water via Fenton-like process and produces hydrogen. A novel solar thermoelectric generator (TEG) unit drives the reactor. For the hot side, the phase change material (PCM) which is heated by the concentrator feeds TEG, and the wastewater stream provides the cold surface. The PEC system is investigated experimentally while the design and calculations of the TEG-PCM sub- system are analyzed theoretically in this study. Moreover, in this study, the synergistic effects of advanced oxidation reactions (AOPs) in a combination of TiO2 photocatalysis are comparatively investigated for hydrogen production and wastewater treatment applications. The synergistic effects of Fenton, Fenton-like, photocatalysis (TiO2/UV) and UV photolysis (H2O2/UV) are investigated individually and in a combination of each other. The effects of various parameters, including pH, type of the electrode and electrolyte and the UV light, on the performance of the combined system are also investigated experimentally. A numerical modeling study is performed to predict the temperature, heat transfer rate and generated power distributions on the thermoelectric generator which is included in the integrated system. The thermodynamic properties of the matter flows at each stage and state point are obtained for the integrated system. The overall energy and exergy efficiencies of the integrated system are 5.2% and 5.5% respectively. The total cost rate of the system is determined to be 0.28 $/h from exergoeconomic analysis results. After 40 minutes of the operation time of the PEC reactor under 2.3V of practical cell potential and 60°C of cell temperature, the reactor produces 22.6 mg of hydrogen and removes 87% of COD. The proposed TEG unit configuration generates 551.2 W of electricity with 7.46% heat to electricity efficiency for the case when the temperature of wastewater is 25°C, and the molten salt is at phase changing temperature of 323°C. Keywords: Efficiency, wastewater treatment, energy, exergy, hydrogen production, photoelectrochemistry, solar energy. i ACKNOWLEDGMENTS First and foremost, I would like to express my most profound gratitude and appreciation to my supervisor Professor Dr. Ibrahim Dincer for giving me this unique opportunity to work in this area, his continuous support and accurate advice throughout my research study. He has provided me with exceptional guidance and encouragement to overcome the challenges that I have faced during my Ph.D. research. I am sincerely honored by having Professor Dr. Dincer as supervisor and inspirational mentor. In addition, I would also like to thank Professor Dr. Bestami Ozkaya for his feedbacks and motivation at critical times. I am so thankful to my colleagues at CERL, Burak Yuzer and Ghassan Chehade who helped me a lot to build my setup and conduct my experiments. In addition, I would like to thank Aaditya Geed who helped me during the literature review and preliminary studies. I am genuinely grateful to all my colleagues and friends in Dr. Dincer`s research group who give me the support and motivation during this journey, particularly, Dr. Yusuf Bicer, Dr. Muhammad Ezzat, Dr. Abdullah Al-Zahrani, Dr. Farrukh Khalid, Maan Al-Zareer, Azzam Abu-Rayash, Osamah Siddiqui, and Huseyin Karasu. The support provided by the Turkish Academy of Sciences (TÜBA) and the Natural Sciences and Engineering Research Council of Canada is gratefully acknowledged. Special thanks and love go to my dear wife Busra, and my daughter Zeynep Sare. Their existence has always been my primary motivation during my stay in Canada. I am sincerely thankful for their sacrifice and blessings. Last but not the least; I would like to express my most profound love and thanks to my parents Hulya and Ahmet Demir for their endless support, determination, inspiration and reassurance throughout my life. Their prayers and good wishes have always been with me. I will always be grateful to them. I would also express my thanks to my elder brother Ali Fatih for being such a strong role model for me. ii TABLE OF CONTENTS ABSTRACT ..................................................................................................................................... i ACKNOWLEDGMENTS .............................................................................................................. ii TABLE OF CONTENTS ............................................................................................................... iii LIST OF FIGURES ....................................................................................................................... vi LIST OF TABLES ........................................................................................................................ xii NOMENCLATURE .................................................................................................................... xiv CHAPTER 1: INTRODUCTION ................................................................................................... 1 1.1 Hydrogen Production ............................................................................................................ 3 1.2 Hydrogen from Renewable Resources .................................................................................. 4 1.2.1 Hydrogen from Biomass ................................................................................................. 5 1.2.2 Wind Energy Based Hydrogen Production .................................................................... 6 1.2.3 Geothermal Energy Based Hydrogen Production .......................................................... 6 1.2.4 Solar Energy Based Hydrogen Production ..................................................................... 7 1.3 Motivation ........................................................................................................................... 10 1.4 Objectives ............................................................................................................................ 11 CHAPTER 2: BACKGROUND AND LITERATURE REVIEW ............................................... 13 2.1 Hydrogen Production Methods from Wastewater ............................................................... 13 2.1.1 Dark Fermentation ........................................................................................................ 14 2.1.2 Photo Fermentation....................................................................................................... 15 2.1.3 Microbial Electrolysis Cells ......................................................................................... 18 2.1.4 Electrochemical Disinfection ....................................................................................... 20 2.1.5 Electrodialysis .............................................................................................................. 22 2.1.6 Electrocoagulation ........................................................................................................ 23 2.2 Advanced Oxidation Processes for Wastewater Treatment ................................................ 25 2.2.1 Electrochemical Oxidation ........................................................................................... 26 2.2.2 Anodic Oxidation ......................................................................................................... 27 2.2.3 Electro-Fenton .............................................................................................................. 27 2.2.4 Photocatalysis ............................................................................................................... 28 2.3 Thermoelectric Generators .................................................................................................. 29 2.4 Literature Review ................................................................................................................ 30 2.5 Main Gaps in the Literature ................................................................................................ 34 CHAPTER 3: SYSTEM DEVELOPMENT AND ANALYSIS .................................................. 36 iii 3.1 System Description ............................................................................................................. 36 3.2 Alternative integrated system layouts ................................................................................. 39 CHAPTER 4: EXPERIMENTAL APPARATUS AND PROCEDURE ...................................... 42 4.1. TiO2 Sol-gel Dip Coating ..................................................................................................