相变电加热地板储热性能的模拟研究毕业论文
2022-04-07 20:40:33
论文总字数:18177字
摘 要
随着经济发展,煤、石油等不可再生能源的产出无法满足日益增长的消耗。节能减排,开发新能源、新技术已是当前国内外发展的突破重点。储热建筑材料具有普通建筑材料无法比拟的热容,可以降低室内温度波动,提高舒适度,使建筑供暖或空调不用或者少用能量,提高能源利用效率,并降低能源的运行费用,是实现建筑节能的有效途径。
相变材料近年来已成为节能减排领域研究的热点,将相变材料与传统的建筑材料结合,可以充分发挥其强大的潜热蓄热能力。在大部分夏热冬冷的地区,由于昼夜温差较小,相变材料蓄热效率低,无法仅依靠被动式蓄热便可满足日常需求。为了解决这一难题,本文引入了毛细管网装置,与相变材料及木纤维材料复合制备了相变蓄能式相变电加热地板。本文的主要研究工作有以下几点:
将石膏基相变储能材料与毛细管网装置结合,制备相变蓄能式相变电加热地板,建立实验模型模拟夏冬两季相变蓄能式相变电加热地板与普通电加热地板的使用情况,并对其表面温度进行实时监控。通过CFD软件建立数值模型,将监测所得的表面温度变化曲线进行对比,发现两者变化趋势基本一致。与普通电加热地板相比,相变蓄能式相变电加热地板的实测结果与模拟结果之间的平均偏差都要大一些。误差主要来自于实体模型制作误差、实验条件误差和数值模拟过程中相关软件参数设置误差等。
对比了夏冬两季普通地板与相变蓄能式相变地板的温度变化曲线,数值模拟与实验测试结果均表明相变材料的存在延缓了相变电加热地板整体的升降温速率,其对温度影响的滞后性较为突出。
对相变蓄能式相变电加热地板的各项参数进行优化分析。最终确定了相变蓄能式相变电加热地板在夏冬两季使用的最优条件为:相变温度区间为26-27℃,相变潜热为150-200kJ/kg,夏季供冷水温为16℃,冬季供暖水温为42℃,毛细管间距为40mm。根据相变蓄能式相变电加热地板在一个完整周期内液相率的变化情况,对其使用方案进行了优化设计,提高了相变材料潜热储能的利用率。
关键词:相变材料; 毛细管网; 相变电加热地板; 数值模拟; 节能评价
Abstract
With the economic development, coal, oil and other non renewable energy output can not meet the growing consumption. Energy saving and emission reduction, the development of new energy, new technology is currently the focus of development at home and abroad. Thermal energy storage building materials with ordinary building materials can not match the heat capacity can reduce indoor temperature fluctuation, improve comfort, the building heating or air conditioning without or with less energy, improve energy efficiency, and reduce the operation cost of the energy, achieve the effective way of building energy conservation.
Phase change materials have become a hot research topic in the field of energy conservation and emission reduction in recent years. The combination of phase change material and traditional building materials can give full play to its powerful latent heat storage capacity. In most in hot summer and cold winter area, due to the smaller temperature difference between day and night, phase change material regenerative efficiency is low, cannot rely solely on passive heat storage will be able to meet the daily needs. In order to solve this problem, this paper introduces a capillary network device, and a phase change material and wood fiber material to prepare a phase change energy storage type phase change electric heating floor. The capillary network can provide artificial cold and heat source for the phase change material, which can help to complete the phase transformation in the daily use. The main research work of this paper is the following:
Gypsum based phase change energy storage materials and capillary network device combination and preparation of phase change energy storage type electrically heated phase-change floor, the establishment of experimental model simulation of summer and winter season two phase change energy storage type phase changing electric floor heating and ordinary electrically heated phase-change floor usage, and the surface temperature in real time monitoring. The numerical model was established by CFD software, and the surface temperature curves were compared and found to be.
basically consistent. Compared with the conventional phase change electric heating floor, the average deviation between the measured results and the simulated results is larger than that of the phase change energy storage type phase change electric heating floor. The error mainly comes from the manufacturing error of the solid model, the error of the experimental conditions and the related software parameter setting errors in the numerical simulation process.
Compared with the summer and winter seasons ordinary phase changing floor and phase change storage can type phase changing floor temperature change curve, numerical simulation and experimental test results show that the existence of phase change material retards the phase change electric floor heating the whole heating and cooling rate, the effect on the temperature hysteresis is more prominent.
The parameters of the phase change energy storage type phase change electric heating floor are optimized and analyzed. Ultimately determine the phase change energy storage type electrically heated phase-change floor in both summer and winter use of the optimality conditions: phase transition temperature range for 26-27 degrees, latent heat of phase change 150-200kJ/kg summer for chilled water temperature 16 degrees, water heating in winter to 42 DEG C, capillary distance is 40mm. According to the phase change energy storage type electrically heated phase-change floor in one complete cycle of the liquid fraction of the changes, the scheme was used to optimize the design, improve the utilization rate of the phase change material for latent heat thermal energy storage.
KEYWORDS: PCMs; Capillary tube; Radiant panels; Numerical simulation; Energy conservation evaluation
目 录
摘 要 Ⅰ
Abstract Ⅲ
第一章 绪论 1
1.1 引言 1
1.2 相变材料与建筑物的结合方式 1
1.2.1 直接掺混法 1
1.2.2 浸渍法 2
1.2.3 微胶囊法 2
1.3 相变材料在建筑节能中的应用方式 2
1.3.1 被动式相变节能 2
1.3.2 主动式相变节能 2
1.4 课题意义及主要研究内容 2
第二章 原材料与实验方法 4
2.1实验模型及实验方案 4
第三章 相变蓄能式相变电加热地板热性能的实验研究及数值模拟 7
3.1 相变电加热地板热性能的实验探究 7
3.2 数值模拟结果分析 11
3.2.1 相变电加热地板实验与模拟温度变化对比 11
3.3 结论 14
第四章 相变蓄能式相变电加热地板节能评价及设计优化 15
4.1 相变电加热地板热性能影响因素分析 15
4.1.1 相变温度区间的影响 15
4.1.2 相变潜热的影响 18
4.1.3 供水水温的影响 20
4.1.4 毛细管间距的影响 22
4.2 结论 23
第五章 结论及展望 25
5.1 结论 25
5.2 展望 25
参考文献 27
致 谢 29
绪论
引言
实现建筑节能,应考虑从两方面出发,即应用新兴的节能技术和开发新型节能建材。目前比较常见的建筑节能技术有门窗节能、屋面节能和墙体节能[5]。其中,墙体节能技术分为外墙外保温和外墙内保温。对于外墙内保温技术来说,其优点是施工简单,保温材料成本较低。缺点是墙体的外侧在温差较大的地区容易出现结露和冷凝的现象,对于相变材料使用寿命的影响较为明显。对于外墙外保温技术来说,其优点是可以避免热桥的影响,提高建筑物的使用寿命。缺点是对于保温材料的耐老化性能和耐火型有较高的要求。由此可见,新兴节能技术的发展和应用与节能建材的提升和进步休戚相关。
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