相变蓄能砌体外墙中夜间通风的热响应研究

发布时间：2018-02-23 20:38

  本文关键词： 相变蓄热 夜间通风 热响应 热舒适度 节电率　出处：《南京工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：经济的高速发展带来了能源的大量消耗,随之众多节能技术也如雨后春笋般涌现出来,其中相伴变材料运用于建筑围护结构中便是其中之一,然而相变材料在研究与使用中发现存在热堆积问题,即昼夜吸放热不平衡,导致第二天相变材料蓄热能力大打折扣。本文以南京地区南外墙为研究对象,选取南京夏季“三伏”期中7月20日一7月24日的综合温度,作为室外计算温度,以这5天的室外综合温度为一个周期,以3周期为一组进行研究讨论。最初,利用Matlab软件基于显热容法模型利用有限体积法对相变通风墙(构造A-—相变石膏置于三排孔空心砌块内孔中,外孔中为空气；构造B—相变石膏置于三排孔空心砌块外孔中,内孔中为空气；)在不同通风流速下的传热过程进行了编程模拟,对之后的实验过程做一定的指导。实验运用热箱法进行,可编程控制仪模拟出室外环境,室内其他表面绝热,相变通风墙堆砌于试件架上,其底部与顶部分别开有进出风口,进风口与离心式无极变频风机相连,相变通风墙内外表面均布置热电偶与热流计实时监控。该实验研究与分析了相变通风蓄能砌体南外墙不同构造(构造A与构造B)时,夜间通风风速变化对热响应的影响。结果表明：相变材料置于空心砌块内侧时优于外置,内置时墙体内表面温度波最大振幅仅为外置时的55.9%；构造A与构造B的最佳流速均为2m/s,且墙体内表面温度波最小振幅以及最大延迟系数分别为1.74℃C、8h和3.72℃C、7h,较之不通风,当量热阻分别增大了115.8%和88.6%,流入室内热量分别减少了38.2%和29.3%。得实验数据之后,所编程序的正确性也能得到验证,构造A与构造B在2m/s的通风流速下墙体内表面温度的相对误差分别为3.9%与4.5%,均小于误差标准5%。与此同时,运用该程序分别对构造C(相变石膏置于三排孔空心砌块内孔中,外孔中为发泡聚苯乙烯)与构造D(相变石膏置于三排孔空心砌块外孔中,内孔中为发泡聚苯乙烯)进行了模拟分析。所得结论：构造C与D的最佳流速亦为2m/s,此时墙体内表面最小振幅、最大延迟系数分别为1.91。C、8h与4.07℃C、7h,且构造C墙体内表面温度最大振幅为3.94℃C,仅为构造D的50.5%,较之不通风,当量热阻分别增大了93.2%和79.6%,流入室内的热量分别减少了35.6%和23.7%；最后,对这四种构造不同通风流速下的室内热舒适度以及节能型亦做了分析。室内热舒适度评价借用“预计平均热感觉指数(PMV)”和“预计不满意者的百分数(PPD)”,而节能性研究最终归结为耗电量,节能率以四种构造通风流速为Om/s时,空调制冷至24℃C所需耗电量为参比对象。研究发现在相同气候条件下,相同通风流速时,相变石膏内置要优于外置,对应为构造A优于构造B,构造C优于构造D；四种构造在最佳流速时不仅室内热舒适度较好,而且总耗电量亦较小,耗电量分别节省了29.5%、27.1%、28.3%及24.6%。
[Abstract]:The rapid development of economy has brought a great deal of energy consumption, and many energy-saving technologies have sprung up, among which the concomitant material used in the building envelope structure is one of them. However, in the research and application of phase change materials, it is found that there is a heat accumulation problem, that is, the heat absorption and exothermic imbalance between day and night, which results in a great loss of the heat storage capacity of the phase change materials the next day. In this paper, the south exterior wall of Nanjing area is taken as the research object. The comprehensive temperature of Nanjing summer "three volts" period from July 20th to July 24th was selected as the outdoor calculation temperature. The outdoor comprehensive temperature of these five days was taken as a period and three cycles as a group to carry on the research and discussion. At first, By using Matlab software based on the model of sensible heat capacity method, a finite volume method is used to construct a phase change ventilation wall with A- phase change gypsum in the inner hole of the hollow block with three rows of holes and air in the outer hole, and the structure of the B phase change gypsum is placed in the outer hole of the hollow block with three rows of holes. The heat transfer process under different ventilation velocity is programmed to guide the later experimental process. The experiment is carried out by means of the hot box method. The programmable controller simulates the outdoor environment and other indoor surfaces adiabatic. The phase change ventilation wall is stacked on the test frame, and the bottom and top of the wall are respectively opened with inlet and outlet, and the inlet is connected with the centrifugal stepless variable frequency fan. Thermocouple and heat flow meter are arranged on the inside and outside of phase change ventilation wall. In this experiment, different structures (structure A and structure B) of the south wall of phase change ventilation storage masonry are studied and analyzed. The effect of nocturnal ventilation wind velocity change on the thermal response. The results show that the phase change material is better than the outside when placed on the inner side of the hollow block. The maximum amplitude of the inner surface temperature wave is only 55.9 when the wall is built in, the optimum velocity of structure A and structure B is both 2 m / s, and the minimum amplitude and maximum delay coefficient of the inner surface temperature wave of the wall are 1.74 鈩，

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