【作者】 吴青昊；

【导师】 巫江虹；

【作者基本信息】 华南理工大学 ， 动力机械及工程， 2010， 硕士

【摘要】 随着经济的发展和人民生活水平的提高,能源的过度开采和低利用效率,所造成的环境问题日益严重,成为制约经济发展和社会进步的不利因素。蓄能技术由于能够解决热能的供给与需求在时间和空间上的不匹配,而成为合理利用能源、减轻环境污染的有效途径。热泵热水器与传统的燃气、电热水器相比,节能效果明显,同时相变蓄热具有蓄热密度大、蓄放热温度恒定、容易控制等优点,热泵系统与蓄热水箱的有机结合已成为热水器研究的新热点。本文将整个蓄热模箱完全浸入水箱中,并将其与蓄热水箱看作一个整体,通过理论模拟与实验分析,研究了复叠式蓄热型热泵热水器相变蓄热系统及其相变蓄热材料的特性。主要工作有:复叠式热泵热水器高、低温级制冷剂选择与各部件设计;适用于热泵系统的相变蓄热材料性能研究;复叠式热泵热水器相变蓄热系统理论模拟;相变蓄热系统蓄热、放热的性能测试实验台。蓄热材料性能实验结果表明,十水碳酸钠与羧甲基纤维素对改善三水醋酸钠的过冷与相分离最为有效,十水碳酸钠最佳比例应在3%~5%,目前最适合与本课题的相变蓄热材料为石蜡-膨胀石墨相变蓄热材料。对相变蓄热系统的理论模拟可知,蓄热模箱孔径有一个最佳尺寸值。蓄、放热过程中,蓄热水箱内部水温与蓄热材料温度存在明显的温度分层作用,蓄热过程中,水箱内的水有明显的自然对流现象。对蓄热系统实验研究可知,蓄热过程中,水箱内水温最高位置为水箱中部(冷凝盘管顶部),放热过程中,蓄热材料可以起到稳定出水温度,减缓出水温度下降速度的作用。本相变蓄热系统在蓄热完成后,一次性提供的热水量,完全可以满足家庭用户的要求。同时,实验值与理论模拟值对比结果吻合良好,两者结果吻合良好,误差在可接受的范围内。更多还原

【Abstract】 With the development of economy and elevation of People’s living level, the over-exploitation of energy, the use in low efficiency, which have resulted in environment pollutions serious day by day, have became adverse factors of restricting economic development and social progress. The technology of thermal storage, which was able to solve the unbalance of energy supply and demand in time and space, has become an effective way in rational use of energy and reducing pollution. Concerning with the traditional gas, electric water heaters,Heat pump water heater have more energy-saving effect. Thermal storage with phase change has become a new hot in energy using because of its advantages such as high energy storage density, charging with a constant temperature, easier to control and so on.By theoretical simulation and experimental analysis, this paper study the phase change thermal storage system and its characteristics of phase-change material（PCM） of a cascade heat pump water heater with PCM, when immersing the PCM heat-exchanger into the container and taking the two as a whole. This research includes the tasks below: selecting the refrigerates of high and low temperature cycles and designing the components for cascade heat pump water heater; study the properties of the applicable PCM; theoretical simulation of the phase-change thermal storage system for the cascade heat pump water heater; thermal storing and exothermic parameters experimental apparatus of the thermal storage system.PCM’s performance experimental results show that Na₂CO₃·10H₂O and are the best and thickener, of carboxymethocel nucleating agent optimal proportionNa₂CO₃·10H₂O is 3%-5%. Paraffin/expanded graphite is the best PCM for this heat pump water heater.The theoretical simulation results show that there exists optimum aperture in the PCM heat-exchanger. In the heat storing and exothermic processes, there is distinct temperature stratification between the water and PCM in the water tank, while it has obvious phenomenon of natural convection in the heat storage process.The experimental study results indicate that the highest water temperature lies on the central of the water tank （top of the condensing coils） in the thermal storage process; in the exothermic process, the thermal storage material has a function of stabilizing and slowing the decreasing rate of temperature of the outlet water. The hot water supplied by the thermal storage process can completely satisfy the requirements of the common family users. Moreover, it is also found that the experimental and theoretical results anastomosed well, with an acceptable error range.更多还原