太阳能供暖二级水箱变容积蓄热系统能量及[火用]分析

Energy and energy analysis of two-stage water tanks variable-volume thermal heat storage system for solar heating

太阳能供暖系统中的固定容积单水箱蓄热系统,在太阳能波动供给和建筑热负荷波动需求之间存在不匹配及灵活性不足的问题。为更高效地利用太阳能,本文对二级水箱温度分层变容积蓄热太阳能供暖系统建立了MATLAB数学模型,包括集热循环、充热循环、取热循环和供热循环四部分及相应的控制策略,并运用Trnsys进行了模型验证。提出了在某时间段内,实际参与充热、取热或同时充热与取热的水箱体积为有效蓄热体积的概念。定义了集热比、有效蓄热体积平均温度、水箱热量取充比和热损比等参数对系统进行了分析与评价。研究表明:与传统的太阳能供暖固定容积单水箱温度分层蓄热系统相比,在整个供暖季,二级水箱变容积蓄热系统的热损失减少了17.2%,取充比增加了6.3%,[火用]效率提高了6.6%,辅热能耗减少了9.5%;在供暖初期,二级水箱变容积蓄热系统的水箱温度响应时间缩短了54.9%,可更灵活快速地用于供热。二级水箱变容积蓄热系统有利于调节供暖季不同时期的供需匹配,具有良好的节能效果,可进一步为太阳能供暖系统的设计与应用提供指导。

The constant-volume water tank thermal heat storage system has the problem of insufficient flexibility and mismatch between the solar energy supply and heat load demand in the solar heating system. To make use of solar energy, a MATLAB numerical model, the twostage variable-volume stratified-temperature water tanks thermal heat storage solar heating system, was established and verified by Trnsys, which was included four cycles, the heat collecting cycle, the heat charging cycle, the heat discharging cycle, the heating cycle, and the corresponding control strategies. The concept of effective volume of thermal heat storage is proposed, which is the volume of the water tank actually involved in heat charge, heat discharge or both in a period of time. To analyze the system, heat collected ratio, average temperature of the effective volume of thermal heat storage, heat discharge to charge ratio of the water tank, and heat loss ratio are also put forward. The results show that, compared with the traditional constant-volume water tank thermal heat storage solar heating system, the heat loss of the two-stage variable-volume water tanks thermal heat storage solar heating system is reduced by 17.2%, heat discharge to charge ratio is increased by 6.3%, the exergy efficiency is increased by 6.6%, and the auxiliary heat is reduced by 9.5% in the whole heating season in Beijing. In the initial stage of heating, the temperature response time of the two-stage variable-volume water tanks thermal heat storage system is reduced by 54.9%,which can be used for heating more quickly. The two-stage variable-volume water tanks thermal heat storage system is beneficial to adjust the matching of supply and demand for heating in different periods, and has a good energy-saving effect, to further guide the design and operation of solar heating systems.