| Along with the consistent growth of global energy consumption, the energy consumption of building has become an indispensable part of the energy consumption of China. The development and utilization of renewable energy is a new alternative energy option after the analysis of the advantages and disadvantages of traditional fossil and nuclear energy, and an important energy strategy to achieve sustainable development. As a kind of clean and renewable energy, solar energy is widely valued both at home and abroad. However, its discontinuity, instability and asynchronism with heat demand limits its development. Thermal storage technology, especially seasonal thermal storage technology, can solve these problems effectively. This technology makes it possible to use solar energy collected in non-heating period during heating period and help addressing the problem of solar energy in sufficiency during the winter and in abundancy during summer. What’s more, it has an important significance on improving the use of solar energy and achieving the reliability of solar heating system.This research analyzes the dynamic thermal process of solar heating system with seasonal water tank heat storage (SHS-SWTHS), extrction and use of heat. Mathematical model for all parts are established and solved, which can simulate the annual water temperature change in the heat storage tank, distribution of energy flow, efficiency of system, choosing ways to extract heat and operation control strategy. Furthermore, the effects of key parameters (V/A (the volume of tank to the area of solar collection), heat collecting efficiency, energy consumption of building and so on) on solar fraction are discussed, the influence of types of extracting heat system which has an key effect to the design and operation of heat storage system and efficiency of extracting heat equipments on the distribution of energy flow, providing reference for the selection of heating mode and operation control strategy. Finally, the seasonal heat storage tank solar heating system of a certain experiment building in Dalian is designed, models are built and the environment benefits are analyzed.For the cold area with a generic solar energy resource type, the main results of this research are as follows:(1) The value of V/A makes appreciable impacts on solar fraction, however safe water temperature control also must be considered. For the cold area with a generic solar energy resource type, such as Dalian, the reasonable range of V/A value is 3～4. The efficiency of solar collector increases 0.1, the solar fraction can increase 26%. If the efficiency of solar collector is too low, it will impact the solar fraction dramatically. In addition, good thermal insulating properties of tank, reduction of heat demand and so on, all will make a good effect on the increasing of solar fraction and energy-efficiency.(2) DC heating with water source heat pump has higher energy efficiency than heat exchanger with water source heat pump with 18% higher solar fraction. Improve the heat exchange efficiency 15%, solar fraction will increase 9%; Improve the COP of heat pump 30%, the solar fraction will increase 3.3%. The higher the efficiency of heat exchanger, the less heat loss; the higher the COP of water source heat pump, the more heat gained from the tank. And it also helps to improve the system efficiency. But in consideration of heat pump’s use in the heating period, the water temperature can’t be too low, so the reasonable COP is 2-3.(3) According to engineering experience and research findings at home and abroad and this study, a comprehensive laboratory building was designed with solar heating system with seasonal water tank heat storage in Dalian, and a mathematical model was established to predict the annual water temperatures and the system energy efficiency. In terms of energy conservation, this system also has significant environmental benefits... |
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