2014年3月18日
New materials and technologies are making it possible to utilize thermal energy more efficiently. Visit Hall 13 at the Hannover Messe (April 7-11) to find out how researchers from the Fraunhofer Energy Alliance are applying this to heat and cool spaces and industrial processes.
Zeolites are crystalline minerals with a porous structure that adsorbs other substances. When the material comes into contact with water vapor, it binds the steam within its pores, releasing heat in the process. © Fraunhofer IGB
In many industrialized countries, city skylines are dominated by imposing glass façades and skyscrapers made of concrete and steel. There is a drawback to these magnificent structures, though – they often get very hot in the summer, so they mostly need elaborate and costly air conditioning systems. And these already account for some 14 percent of Germany’s annual energy consumption. Experts reckon that total cooling requirements in buildings will triple by 2020.
Cooling and heating using metal organic frameworks
热驱动的冷却系统是传统空调的一种可能替代方法。这些系统使用液体的蒸发，例如低压下的水以去除环境中的热量 - 一种节能冷却方法。现在，来自弗雷堡的弗劳恩霍夫太阳能系统ISE研究所的研究人员正在研究可以存储特别大量水蒸气的创新吸附剂。为了开发这种材料，研究人员已转向金属有机框架（MOF）。弗劳恩霍夫·伊斯（Fraunhofer Ise）的斯蒂芬·亨尼格（Stefan Henniger）博士说：“这种材料高度多孔，可以吸附其自身体重的1.4倍以上。”
MOF也可以用于热驱动的热泵中。电动热泵具有电压缩机，而在这些泵中，吸附剂在水作为冷却液时扮演“热压缩机”的作用。气态冷却液被吸附剂吸附，因此离开了气态。这种吸附到材料的空心内部的热量被热交换器传递，可用于加热。为此，必须将吸附剂应用于热交换器的表面，以使冷却液连续蒸发直至吸附剂饱和。一旦达到了最大吸附能力，就会使用驱动热来驱动储存的冷却液并液化。该过程中释放的冷凝热也可以用于加热。
为了利用MOF的全部潜力，对于水蒸气来说，轻松进入材料的内表面和孔隙空间也很重要，而且还可以从材料中脱离热量。为了帮助这一过程，Fraunhofer ISE的专家开发了一种新的涂料技术，并为其申请了专利。该技术允许将新吸附剂应用于诸如热交换器之类的设备，而不会阻塞热量和传质。2020欧洲杯下注官网这项研究由德国联邦经济事务和能源部资助。
储存中的热量
Industrial facilities, power stations and biogas plants all make use of processes in which heat is essentially a waste product. Currently, hardly any of this heat energy is put to use – something that scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart want to change. The researchers are working on developing and optimizing zeolite thermal storage systems.
沸石是具有多孔结构的晶体矿物质，可吸附其他物质，例如水。它们的内部表面积可高达每克1000平方米。当沸石与水蒸气接触时，它会结合其毛孔中的水分子，从而在此过程中释放热量。干燥材料是储存热量的一种方式；一旦水蒸气再次吸附，这种能量就会释放。Fraunhofer IGB的专家现在正在开发技术，以允许使用这种储藏技术。
Thermochemical heat storage systems based on a combination of zeolites and water have the potential to amass up to 180 kilowatt hours of energy per cubic meter depending on the charging temperature and the application. To put this into perspective, traditional hot water energy storage systems normally have an energy density of less than 60 kilowatt hours per cubic meter. However, zeolite sorptive thermal storage devices are in this stage of development relatively expensive. “From an economic and technical standpoint, we currently see this technology being implemented in industry,” says Mike Blicker, group manager, heat and sorption systems at Fraunhofer IGB.
来源：http://www.fraunhofer.de/