相变热回收式通风装置的研发及性能测试研究

随着建筑节能标准的提高,建筑外窗气密性要求不断提高。靠门窗渗透的自然通风量已不能满足室内空气质量的要求。采用机械通风的方式引入新风也存在着通风量的大小及通风模式会影响建筑节能的问题。为此,将相变蓄能技术应用于民用建筑的机械通风系统,研发出一种相变热回收式通风装置,以更好地解决室内空气质量和节能问题。所研发装置利用相变材料的蓄、放热性能,通过交替运行的通风模式,以及通风装置的不断循环,实现无管道式的相变热回收式建筑通风系统。主要采用实验研究的方法,在人工气候室内对研发样机进行了2个蓄、放热周期(4种工况)的测试研究。结果表明,相变热回收式通风装置的进口温度恒定、出口温度随时间不断变化,不同时间阶段呈现不同的变化趋势。第一时间阶段,即初始阶段,出口温度随时间变化剧烈,表明相变蓄能装置进入相变阶段,相变潜热量不断增大。第二时间阶段,即相变阶段,出口温度随时间呈线性变化,表明相变蓄能装置温度恒定,与空气流体发生稳定的相变传热。第三时间阶段,即完成阶段,出口温度变化小,基本接近进口温度,表明相变蓄能装置相变结束。从相变传热机理进行分析,固-液相变传热过程主要包括液态显热蓄(放)热、相变潜热蓄(放)热和固态显热(蓄)放热3个阶段,实验过程中出口温度随时间变化呈现出的几个时间阶段的不同规律,与相变传热机理有关联且相互对应。相变热回收式通风装置的风量恒定、不同进口温度工况下的对比数据表明,进口温度与相变温度的温差越大,初始阶段的出口温度变化越剧烈,相变阶段的出口温度线性变化率越大,且蓄、放热效率越高。进口温度与相变温度的温差约17℃时,蓄、放热效率分别达到56.2%(蓄)、50.8%(放)。

Performance Test and Develop of Phase Change Heat Recovery Ventilation Device

As building-energy-conservation regulations become more stringent, the requirements on the air-tightness of exterior doors and windows are becoming stricter.The infiltrated outdoor air amount can''t meet the required ventilation volume for indoor air quality anymore.If fresh air were brought into buildings through mechanical ventilation, the ventilation volume and ventilation mode would affect building energy usage.Therefore, to better solve the contradiction between indoor air quality and building energy conservation, we investigated how phase change energy storage technology can be applied to mechanical ventilation systems of civil buildings, and developed a phase change heat recovery ventilation device.The device takes the advantage of heat storage and heat release performance of phase change materials.As ventilation modes change alternatively and the ventilation device cycles constantly, non-ducted phase change heat recovery ventilation system can be achieved.This paper mainly adopts the experimental research method for testing and analyzing heat storage and heat release performance of the prototype in the artificial climate chamber.The experiment includes running two heat storage and heat release cycles (adding up to 4 kinds of experimental conditions).The results show that the outlet temperature changes with time when the inlet temperature of phase change heat recovery ventilation device is constant and different trends appear in the different time-stages.During the first time-stage, namely, the initial stage, the outlet temperature changes dramatically with time.This shows that phase change energy storage unit begins to change phase and phase change latent heat quantity increases gradually.During the second time-stage, namely, the phase change stage, the outlet temperature changes linearly with time.This shows that the temperature of phase change energy storage unit is constant and phase change heat transfer with air stream is steady.During the third time-stage, namely, the completion stage, the outlet temperature slightly changes with time and is close to inlet temperature.This shows that phase change energy storage unit completes phase change heat transfer.Regarding the phase change heat transfer mechanism, solid-liquid phase change heat transfer process mainly includes three stages, respectively, sensible heat storage or release by liquid state, latent heat storage or release by phase change state, and sensible heat storage or release by solid state.In the experiment, the outlet temperature change regularity of different stage is correlated with and corresponds to the phase change heat transfer mechanism.The comparison experimental data of different inlet temperatures with constant air volume conditions shows that the greater the difference between inlet temperature and phase change temperature, the stronger the change of outlet temperature in the initial stage, the greater the linear change rates of the outlet temperature in the phase change stage, and the higher the heat storage and heat release efficiency.When the inlet and phase change temperature difference was about 17 ℃, the heat storage efficiency reached 56.2%, and the heat release efficiency reached 50.8%.