太阳能热水器是一种成熟的可再生能源技术，已在世界各地广泛采用。在该项目中，我们通过使用“干式可拉伸”碳纳米管（CNT）板涂层来增加太阳能吸收，并使用石蜡相变材料（PCM）来增加真空管集热器中的蓄热和传热层，从而显著改进了真空管集热器（ETC）。由于通常情况下，尤其是粉末形式的相变材料的传热率低、热扩散率和导热性低，因此相变材料本身可能无效。 通过将碳纳米管层（具有较高的热扩散率和导电率）作为PCM（以微胶囊形式）的优质介质，我们能够克服PCM的缺点，并设计出一款创新高效的太阳能热水器。这种设计可以直接在集热器上储热，即使在阴天也可以更稳定地输出热量，在夜间可以长时间输出热量。除了是优秀的黑体吸收剂外，碳纳米管板也是焦耳加热的快速来源，当阳光不足时，可以利用碳纳米管板对太阳能集热器进行电加热。 通过将低功率电加热直接并入真空管太阳能集热器，这样的改进将完全消除对单独的燃气或电热水系统的需求。引用:ASHRAE论文CD:2014 ASHRAE冬季会议，纽约

Solar water heaters are a well-established renewable energy technology that has been widely adopted around the world. In this project wehave significantly improved the evacuated solar tube collectors (ETC) by utilizing the "dry-drawable" carbon nanotube (CNT) sheets coatings forincreasing solar energy absorption and paraffin phase change materials (PCMs) for increasing the heat accumulation and heat transfer layers inevacuated tube collectors. PCM by itself may not be effective due to the poor heat transfer rate and low thermal diffusivity and thermalconductivity of PCMs in general, particular in powder form. By combining CNT layers (with high thermal diffusivity and conductivity) as anexcellent medium for PCM (in form of microcapsules), we are able to overcome the shortcomings of PCMs and design an innovative and efficientsolar water heater. Such design enables heat storage directly on the collector for a more constant output even on a cloudy day and prolonged outputof heat at night. In addition to being excellent blackbody absorbers, CNT sheets are also a fast source of Joule heating and can be utilized to heatelectrically the solar collectors when sunlight is not sufficient. Such improvement would entirely eliminate the need for a separate gas or electricbooster water heating system, by incorporating low power electric heating directly into the evacuated tube solar collector.