Rolka Paulina, Karwacki Jaroslaw, Jaworski Maciej
Institute of Fluid Flow Machinery, Polish Academy of Sciences, 80-231 Gdansk, Poland.
Institute of Heat Engineering, Warsaw University of Technology, 00-665 Warsaw, Poland.
Materials (Basel). 2021 Sep 9;14(18):5172. doi: 10.3390/ma14185172.
Energy storage is one of the most effective ways to increase energy savings and efficiency of heating and air conditioning systems. Phase change materials (PCMs) are increasingly used in latent heat thermal energy storage (LHTES) systems to increase their capacity. In such systems, costs are a very important factor of viability so the typical heat transfer elements like fin-and-tube heat exchangers are used to construct the LHTES. The problem of this approach is a possibility of corrosion of metals in contact with PCM that shortens the life cycle of LHTES. Therefore, the main objective of this work is an experimental study of the compatibility of metals typically used in fin-and-tube heat exchangers (copper and aluminum) with three commercially available organic PCMs (RT15, RT18HC, and RT22HC). Compatibility of PCMs with copper and aluminum was tested for a period of approximately two months, during which a total of 35 heating and cooling cycles were carried out, each with a complete phase transition of the tested materials. In the course of the tests it was assessed whether the PCM caused corrosion of the tested metals. The evaluation was based on the gravimetric method, calculation of corrosion rate, and visual observations and measurements of the features on the metal sample's surface using optical microscope. It was determined that RT15, RT18 HC, and RT22 HC show low corrosion rates for aluminum and copper samples. The visual tests indicate that there was no change in the PCM solutions during the tests, only a sediment was observed for the samples with the combination of copper and aluminum. Microscopic examination of the surface of the samples did not show any significant surface changes, except for the aluminum samples, on the surface of which local microdefects were observed. It follows from the present results that copper and aluminum can be used to design the heat transfer surface in contact with the chosen PCMs.
能量存储是提高供暖和空调系统节能及效率的最有效方法之一。相变材料（PCM）越来越多地用于潜热蓄热（LHTES）系统以增加其容量。在这类系统中，成本是可行性的一个非常重要的因素，因此典型的传热元件如翅片管换热器被用于构建LHTES。这种方法的问题在于与PCM接触的金属可能会腐蚀，从而缩短LHTES的生命周期。因此，这项工作的主要目标是对翅片管换热器中常用的金属（铜和铝）与三种市售有机PCM（RT15、RT18HC和RT22HC）的兼容性进行实验研究。对PCM与铜和铝的兼容性进行了约两个月的测试，在此期间共进行了35个加热和冷却循环，每个循环中测试材料都有完整的相变。在测试过程中，评估了PCM是否会导致测试金属的腐蚀。评估基于重量法、腐蚀速率计算以及使用光学显微镜对金属样品表面特征进行的目视观察和测量。结果确定，RT15、RT18 HC和RT22 HC对铝和铜样品显示出低腐蚀速率。目视测试表明，测试过程中PCM溶液没有变化，只有铜和铝组合的样品中观察到有沉淀物。对样品表面的显微镜检查未显示任何明显的表面变化，但铝样品表面观察到局部微缺陷。从目前的结果可以得出，铜和铝可用于设计与所选PCM接触的传热表面。
