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In order to investigate the recycling technology for efficiently recovering low-temperature wastewater waste heat from industrial production, we built an experimental device for forced boiling heat transfer in an annular tube. This paper takes a ring casing evaporator with an inner tube diameter of 30 mm, a length of 1450 mm, a wall thickness of 0.8 mm, and an outer tube diameter of 14.2 mm, which was used as the main object of study. We conducted experimental research on heat transfer in single-phase liquid flow and two-phase boiling phase change within annular tubes by varying the inlet circulating hot water temperature (60–85 °C), the mass flow rate of the circulating mass (0.85, 1.27, 1.69 kg m−2 s−1), and the inclination angle (0°–90°). The research results indicate that the heat transfer coefficient of boiling phase change within annular sleeves is significantly enhanced compared to convective heat transfer of single-phase liquid flow within annular tubes. This signifies that employing heat pipe technology for waste heat recovery can achieve highly efficient heat transfer processes. This study also reveals that with an increase in the inclination angle, the heat transfer coefficient on the boiling surface follows a trend of initial increase followed by a decrease. Near an inclination angle of 30° within the annular jacket tube, the heat transfer coefficient of two-phase boiling phase change reaches its maximum value. The findings of this study provide certain theoretical guidance for the application of heat pipe energy-saving technology in the field of medium- and low-temperature waste water recovery and utilization. [ABSTRACT FROM AUTHOR]

AlN films were deposited on microscopy glass slide and silicon (111 orientation) substrates by reactive ac magnetron sputtering using two nitrogen concentrations and three discharge powers of 1.5, 2.5, and 5.0 kW. X-ray diffraction studies showed that films prepared on glass and Si substrates were of hexagonal wurtizite phase. Films on Si substrates also contained small amounts of the cubic phase of AlN besides the predominantly hexagonal wurtizite phase. AlN coatings on glass substrates were textured towards the (00·2) plane; this preferred orientation of crystals was found to decrease with increase in sputtering power. Scanning electron microscopy studies showed that AlN films prepared at higher nitrogen concentration have a microstructure consisting of pebblelike crystals, some of which were hexagonal in shape. The crystal size in the coatings increased with sputtering power and was in the range of 70–230 nm. [ABSTRACT FROM AUTHOR]