Author: Sit, Hong Ting
Title: Optimization of constant inflow for water tank feeding unsteady time-variant demands
Advisors: Wong, Ling Tim (BSE)
Degree: M.Eng.
Year: 2020
Subject: Buildings -- Energy conservation
Hong Kong Polytechnic University -- Dissertations
Department: Department of Building Services Engineering
Pages: x, 74 pages : color illustrations
Language: English
Abstract: Energy resources are vital to support people's daily life. However, they are limited and even in shortage. A balance needs to be made between meeting occupants' satisfaction and saving energy resources. To improve the efficient use of energy in the water supply system, this research focuses on the energy-saving potential by optimizing the constant inflow for water tank feeding unsteady time-variant demands, while ensuring the mass balance of water flow in the supply tank at all time, especially the peak usage periods. By minimizing the inflow rate, the velocity of water inflow and the frictional loss can be reduced. Therefore, less energy is required to deal with friction. A case study was conducted to help achieve this goal. In the process, simulation based on the Monte Carlo method was used to obtain data on the water flow at the inlet and outlet of the water tank and water volume in the tank for analysis. In this study, other than the commonly used loading unit method, a mass-balance model was adopted to determine the inflow rate. Thus, possible improvements to the amount of water inflow and pump schedule were suggested to optimize the system. The case study proved that the amount of inflow can be adjusted to the optimized level with around 40% reduction with the help of frequency inverter, while the water level in the tank is satisfying. Thus, energy consumption can be minimized while meeting occupants' demands. However, the potential degree of energy reduction is affected by many factors. Even if the percentage of change in the inflow is the same, the energy savings in different situations can be different. Therefore, further study of the energy-saving effects caused by different pipe sizes may help maximize energy savings.
Rights: All rights reserved
Access: restricted access

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