Author: Shen, Zhicheng
Title: Research and development on a novel hydropower system with integrated turbine generator for efficient energy recovery from water supply pipeline
Advisors: Yang, Hongxing (BEEE)
Lu, Lin (BEEE)
Degree: Ph.D.
Year: 2023
Subject: Small scale hydropower
Water-pipes -- Inspection
Water-pipes -- China -- Hong Kong -- Maintenance and repair
Water-supply -- China -- Hong Kong
Hong Kong Polytechnic University -- Dissertations
Department: Department of Building Environment and Energy Engineering
Pages: xxv, 162 pages : color illustrations
Language: English
Abstract: In recent years, water distribution networks around the world have suffered from water pipe aging problems, which incur safety and reliability issues in urban water distribution systems, especially in Hong Kong, where a lot of fresh water is lost due to water pipe damage. A water intelligent network (WIN) is capable of facilitating leakage detection by monitoring water pipelines with wireless pressure and other sensors, which can significantly reduce water loss and improve water supply service quality. However, existing WIN systems have been encountering a knotty problem of non-continuous and unstable power supply because batteries have to be replaced frequently, and the capacities of batteries are limited. It is thus necessary to develop a micro water turbine system with intelligent control and a novel design generator with low water head reduction for generate small amount of power and supplying to WIN.
Firstly, a comprehensive literature review of the current power supply technologies for remote data monitoring systems was conducted. Among all the existing technical solutions, the spot utilization of surplus pressure in water pipelines to generate and supply power to WIN systems using micro hydropower generation systems has gained significant attention. Many scholars have conducted exploratory research and laboratory experiments. However, there is a lack of a one-stop micro­-hydropower solution suitable for a WIN application in engineering practice, i.e., all the inline hydropower systems are not integrated systems. The main research gap was identified accordingly which is to develop a micro hydropower harvesting system with an integrated turbine generator as a whole set.
Secondly, a novel integrated hydropower harvesting system (IHHS) was developed in this project, including three main research and development tasks: First, the development of a novel inline hydropower generator (IHG) with Computational Fluid Dynamics (CFD) simulation and laboratory experiments; Second, development of an automatic control unit (ACU) with power management and data transmission functions, together with the development of ACU control and software, user interface (UI), and data server software; Third, conduct field tests of the developed prototypes on the water supply pipelines in Hong Kong. The test results were highly encouraging, as the IHHS demonstrated stable and reliable performance for different water flow conditions.
Thirdly, aiming to address the issues of mechanical seal frictional resistance and leakage risk found in the long-term durability tests before, a novel micro turbine generator with a magnet coupling was developed. Comprehensive performance simulations and experiments were carried out. The laboratory test results demonstrated that the generator with magnet coupling has significantly improved the performance of the system compared with its traditional design. 12.0-13.3% extra power generation was increased due to this novel development because of less mechanical friction. The performance prediction, based on the real on-site data collected from a local commercial building estate, indicates that the annual power generation for the sample site can be increased by 19.9%, which substantiates the high potential of adopting this new technology on the IHHS to its improve energy efficiency and operation reliability.
Although the magnet coupling shows great energy efficacy benefits in micro hydropower applications, its additional size and weight bring technical disadvantages as most of the micro hydropower applications of WIN systems are in narrow and confined underground inspection chambers. To further expand the application scope of the IHHS, a more compact design of the integrated permeant magnetic generator (IPMG) was finally proposed, designed, optimized, and tested. The prototype design is determined with the assistance of FEM analysis. Then, the integrated generator design and its simulation results were validated by laboratory experiments. The IPMG was then connected to a water turbine to determine its performance in real water flow. The laboratory test performance, when real on-site data is taken into account, demonstrated that the IPMG design brings significant performance improvement in overall energy efficiency and annual power generation. According to the laboratory test, the average power output of the IPMG is 21.8% higher than that of the PMG. Based on the prediction model developed in this research and one-year water pipeline flow data in Hong Kong, the annual power generations of the IPMG and PMG were predicted. The result indicates that the IPMG has 35.8% more annual power generation improvement than that of the PMG with a traditional mechanical sealing structure, which will be very useful for low-water flow pipelines, e.g., in night time and daytime periods when less number of residents stay at home so that less amount of water is consumed. The optimization of the isolation and the generator design parameters considering multiple factors were also studied to provide guidance for researchers and engineers to develop the IPMG in the future.
The study is aimed to propose and develop a practical, cost-efficient one-stop on-site power supply solution for standalone WIN applications. The novel design and optimization studies performed in this thesis provide a good reference for the future development of this technology and its application on water supply pipelines in urban areas.
Rights: All rights reserved
Access: open access

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