Document Version Peer reviewed versionLink back to DTU Orbit Citation (APA): Englmair, G., Moser, C., Furbo, S., Dannemand, M., & Fan, J. (2018). Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system. Applied Energy, 221, 522-534. https://doi. Highlights Combined short-and long-term heat-storage prototype for domestic solar heating  Interplay of solar collectors, four 200 kg PCM units and a 735 L water tank  Functionality of a segmented heat storage utilizing stable supercooling of SAT  Solidification of supercooled SAT was started by a seed crystal injection device  Supply temperatures and thermal power during PCM charge and discharge were evaluated Abstract A solar heating system with 22.4 m² of solar collectors, a heat storage prototype consisting of four 200 kg phase-change material (PCM) storage units, and a 735 L water tank was designed to improve solar heat supply in single-family houses. The PCM storage utilized stable supercooling of sodium acetate trihydrate composites to conserve the latent heat of fusion for long-term heat storage. A control strategy directed heat from a solar collector array to either the PCM storage or a water buffer storage. Several PCM units had to be charged in parallel when the solar collector output peaked at 16 kW. A single unit was charged with 27.4 kWh of heat within four hours on a sunny day, and the PCM temperature increased from 20 ºC to 80 ºC. The sensible heat from a single PCM unit was transferred to the water tankstarting with about 32 kW of thermal power after it had fully melted at 80 ºC. A mechanical seed crystal injection device was used to initialize the crystallisation of the sodium acetate trihydrate after it had supercooled to room temperature. The unit discharge during solidification peaked at 8 kW. Reliable supercooling was achieved in three of the four units. About 80% of latent heat of fusion was transferred from PCM units after solidification of supercooled sodium acetate trihydrate to the water tank within 5 hours. Functionality tests with practical operation conditions on the novel, modular heat-storage configuration showed its applicability for domestic hot water supply and space heating. Keywords: Solar heating system; heat storage prototype; phase change material; sodium acetate trihydrate; stable supercooling. P pump PCM phase-change material SA sodium acetate SAT sodium acetate trihydrate SH space heating V 2-way valve

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Highlights On-demand crystallization of sodium acetate trihydrate for heat storage  A numerical model was validated with data from system demonstration  Sensitivity analysis of solar collector area and heat storage volume  Annual solar fraction of 71% with 0.6 m 3 water and 1 m 3 of PCM for heat storage  1000 kWh of heat supplied by PCM units with 5.5 annual heat storage cycles

SummaryThe use of ultrabright light-emitting diodes as a potential substitute for conventional excitation light sources in fluorescence microscopy is demonstrated. We integrated ultrabright light-emitting diodes in the filter block of a conventional fluorescence microscope together with a collimating Fresnel lens, a holographic diffuser and emission filters. This setup enabled convenient changes between different excitation light sources and resulted in high excitation efficiencies. Quantitative comparison of image intensities of test samples revealed that light-emitting diodes yielded intensities in the range of a mercury arc lamp depending on the wavelength. The use of ultrabright light-emitting diodes also enabled luminescence lifetime imaging without the need for image intensification.