Green energy-storage materials enable the sustainable use of renewable energy and waste heat. As such, a form-stable phase-change nanohybrid (PCN) is demonstrated to solve the fluidity and leakage issues typical of phase-change materials (PCMs). Here, we introduce the advantage of solid-to-gel transition to overcome the drawbacks of typical solid-to-liquid counterparts in applications related to thermal energy storage and regulation. Polyethylene glycol (PEG) is form-stabilized with cellulose nanofibrils (CNFs) through surface interactions. The cellulosic nanofibrillar matrix is shown to act as an organogelator of highly loaded PEG melt (85 wt %) while ensuring the absence of leakage. CNFs also preserve the physical structure of the PCM and facilitate handling above its fusion temperature. The porous CNF scaffold, its crystalline structure, and the ability to hold PEG in the PCN are characterized by optical and scanning electron imaging, infrared spectroscopy, and X-ray diffraction. By the selection of the PEG molecular mass, the lightweight PCN provides a tailorable fusion temperature in the range between 18 and 65 °C for a latent heat storage of up to 146 J/g. The proposed PCN shows remarkable repeatability in latent heat storage after 100 heating/cooling cycles as assessed by differential scanning calorimetry. The thermal regulation and light-to-heat conversion of the PCN are confirmed via infrared thermal imaging under simulated sunlight and in a thermal chamber, outperforming those of a reference, commercial insulation material. Our PCN is easily processed as a structurally stable design, including three-dimensional, two-dimensional (films), and one-dimensional (filaments) materials; they are, respectively, synthesized by direct ink writing, casting/molding, and wet spinning. We demonstrate the prospects of the lightweight, green nanohybrid for smart-energy buildings and waste heat-generating electronics for thermal energy storage and management.

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Liquid release and spread as a consequence of impact of missile on a wall are of interest for the determination of consequences of an airplane crash on a structure. These phenomena have been studied in medium-scale IMPACT tests at the Technical Research Centre of Finland (VTT). In these tests, deformable cylindrical steel or aluminium projectiles impacted a solid concrete wall or a steel force plate. Some of the tests were conducted using a fluid filled ("wet") projectile. The length of the wet projectiles ranged from 0.5 to 1.5 m, the water mass inside the projectile from 15 to 68 kg and the impact velocity from 70 to 177 m/s. This paper concentrates on the methods applied during the impact tests to measure the liquid dispersal phenomena. The main results of preliminary simulations of liquid spread are also presented. So far, the main parameters of the liquid phenomena measured in the experiments are the velocity and direction of the liquid front coming out from the ruptured projectile, water pooling area on the floor, extent of liquid dispersal far from the target, and drop size of the liquid spray. The velocity and direction of the front of ejected liquid within an approximately 2 m distance from the target was measured using high-speed (1000 fps) video cameras. In addition, normal DV cameras were located around the target to detect the angle and direction of liquid spread, a general view of the liquid spray, and the average velocity of the liquid front up to approximately 5 m from the target. The water-pooling area was detected using a measuring grid drawn on the floor and photographing the wet areas. The extent of dispersal of liquid spray far from the impact target was measured with the pure collection trays (steel plates located on the floor). Oil-coated trays were also used to capture the deposited droplets and to measure the drop size using the macro photography technique and proper image analysis software. Specific arrangements to photograph the size and velocity of airborne droplets in the vicinity of the impact target were also developed. This system consists of both a high-speed (1000 fps) and a high-shutter-speed (t = 1 µs) camera and a stroboscope light (flash time 1 µs) for backward illumination. The preliminary simulations of liquid dispersal were made using the 3-D Fire Dynamics Simulator code (FDS). The main objective of the analyses was to assess the usability of the code for the simulation of the two-phase flows involving high-speed droplets and to support the experimental work by providing an initial estimate of the spray behaviour. The simulation results indicated that FDS is a tool usable in simulating this kind of behaviour provided that the initial conditions of air speed, angle of droplet release, droplet size distribution, and initial droplet speed are specified. Given these, the formation of the water cloud and the final extent of liquid dispersal can be predicted by FDS reasonably well. Future work with the FDS program should include a validation of the some sub-models. Also, some IM...

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The effects of flashing on black liquor spray patterns were investigated by analyzing numerous spray images obtained from laboratory experiments using small scale splashplate nozzles with water and experiments using actual size splashplate nozzles with black liquor. The results showed that flashing produces small droplets and increases droplet velocity. The liquor mass flow rate varies with direction: the rate is higher at the center than at the sides of the spray sheet, particularly at a lower excess temperature. At a higher excess temperature, however, the mass distribution becomes more uniform across the spray sheet. Criteria were developed for predicting the onset of flashing and for estimating the mean droplet size of the black liquor spray under flashing conditions.

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