The aim of this project was to find a range of phase change materials that could be used for the storage of solar thermal energy at low to medium temperatures (melting point below 373 K) for the application of heating supply in buildings. This has been done by collecting information about the properties (melting temperature, latent heat and density) of different PCMs from five currently commercial manufacturers that has been found in the literature.
The materials found are both of the organic and inorganic type, each with it’s pros and cons. Organics are flammable and most are neither biodegradable nor renewable. Inorganic PCMs (salt hydrates) are corrosive to metals and not flammable. Both types are in general regarded as non-toxic, but both are dangerous if ingested and dust from salt hydrates can irritate eyes and skin.
A numerical simulation has been run with the properties obtained from the testing of RT70HC. It was a 2D simulation with PCM in a square container. The figure below shows the liquid fraction at the top and to the left and temperatures to the right, timestamps can be seen to the left in the figure. The simulated time is two hours which took a day to finish. The PCM is almost completely melted after two hours, with some solid material at the bottom.
The testing of the materials previously received is completed. For the thermal characterization differential scanning calorimetry (DSC) and rotational rheometry for the rheological characterization was used. A water bath was used for the density determination of the materials, though not being so accurate. The results can be seen in the figures below.
Today we got a package from Berlin with two PCMs that we ordered not long ago. Since easter is right around the corner, any testing will have to wait untill after the holidays.
Two paraffins from Berlin.
Here is some photos of the solar collector rig, installed on the roof of one of the university’s laboratory buidlings. The energy collected by the panels are taken up by water that is pumped through the panels. The water is then heat exchanged with water in containers/barrels that can also be seen on the pictures. My job in this bachelor project is to find phase change materials (PCMs) that can store more energy than water (within the same temperature interval) taking into account melting temperature, energy density, safety of operation and cost.
Two panels for collecting solar energy. The container (blue barrel) can be seen to the right.
View from the back of the panels.
I have now arrived at the university (Universidad Politécnica de Cartagena (UPCT)) in Cartagena, Spain and more posts will come as I make progress in my project.