Alex Sinyavin

Pipeline insulation is critical for energy-efficient building heating systems, as moisture ingress significantly degrades thermal performance and increases energy losses. This study experimentally evaluated how quality characteristics of mineral wool affect the thermal performance of pipe insulations (wired mats) at temperatures ranging from 20 °C to 85 °C with moisture content up to 12% by weight. Thermal conductivity measurements were performed on two representative samples using the “guarded hot pipe” and direct water injections. Thermal conductivity measurements confirmed the expected increase with rising temperature and moisture content for both samples. In a dry state, quality parameters have practically no effect on the thermal conductivity (0.036–0.041 W∙m⁻¹·K⁻¹). In a low-temperature regime, the inferior quality sample (Sample A) at a maximum moisture content of 12% exhibited thermal conductivity of 0.042 W∙m⁻¹·K⁻¹, and the sample with the best hydrophobic treatment (Sample B) had a thermal conductivity of 0.050 W∙m⁻¹·K⁻¹. At an elevated temperature at a moisture content of 12%, Sample A and Sample B had thermal conductivity of 0.077 W∙m⁻¹·K⁻¹, and 0.109 W∙m⁻¹·K⁻¹, respectively. The results suggest that highly hydrophobic materials are advantageous only in high-temperature applications where rapid moisture removal occurs after short-term ingress, providing critical data for optimizing insulation selection and improving energy conservation in heating networks.

Numerical investigations of heat transfer for forced, mixed, and natural convection conditions within an annular channel are carried out. The main objective was to investigate, for the first time, the effect of the radial cylinder array on heat transfer in the annular channel with the rotating cylinder. The governing equations for velocity and temperature with the Boussinesq approximation were solved using the finite-volume method. The heat transfer quantities were obtained for different Rayleigh numbers (10⁴–10⁶), the radius ratios (1.4–2.6), the radial cylinder spacing, and for different rotating velocities in the form of the Richardson number (10⁻²–10⁴). The Prandtl number was 0.7. It has been shown that radial cylinders do not influence significantly the intensity and the local distribution of heat transfer on the inner rotating cylinder. The Nusselt number was 1.4–2.0 times higher on the radial cylinder array for all convection modes relative to the outer flat surface. For all annuli gaps with radial cylinders, the maximal values of the Nusselt number were observed with an increase of the radial spacing of cylinders.

Open-cell foams are attractive for heat transfer enhancement in many engineering applications. Forced pulsations can lead to additional heat transfer enhancement in porous media. Studies of heat transfer in open-cell foams under forced pulsation conditions are limited. Therefore, in this work, the possibility of heat transfer enhancement in porous media with flow pulsations is studied by a numerical simulation. To generate the 3D open-cell foams, the Laguerre–Voronoi tessellation method was used. The foam porosity was 0.743, 0.864, and 0.954. The Reynolds numbers ranged from 10 to 55, and the products of the relative amplitude and the Strouhal numbers ranged from 0.114 to 0.344. Heat transfer was studied under the conditions of symmetric and asymmetric pulsations. The results of numerical simulation showed that an increase in the amplitude of pulsations led to an augmentation of heat transfer for all studied porosities. The maximum intensification of heat transfer was 43%. Symmetric pulsations were more efficient than asymmetric pulsations, with Reynolds numbers less than 25. The Thermal Performance Factor was always higher for asymmetric pulsations, due to the friction factor for symmetrical pulsations being much higher than for asymmetric pulsations. Based on the results of a numerical simulation, empirical correlations were obtained to predict the heat transfer intensification in porous media for a steady and pulsating flow.

Сахарная промышленность России играет огромную роль в обеспечении продовольственной безопасности страны и является стратегической отраслью. Из 90 имеющихся на сегодняшний день сахарных заводов в России треть закрыты в связи с нерентабельностью, связанной с высокой себестоимостью производства сахара из-за низкой производительности оборудования по сырью. Сырьем для производства является сахарная свекла преимущественно отечественного производства. Места расположения большинства сахарных заводов – небольшие муниципальные образования, для которых они являются градообразующими предприятиями. Для возрождения закрытых сахарных заводов необходимо наращивание их производительности, что трудновыполнимо из-за того, что в диффузионном отделении каждого сахарного завода находится один крупногабаритный импортный диффузионный аппарат механического типа, не позволяющий нарастить производительность никаким другим способом, кроме покупки нового более высокопроизводительного дорогого импортного диффузионного аппарата механического типа. В нынешних условиях неопределенностей и разрыва торговых связей с другими странами необходимы новые поставщики высокопроизводительных диффузионных аппаратов в самой России, которые не уступали бы западным образцам. Российская компания ИВЦ «Инжехим» разработала диффузионный пульсационный аппарат (ДПА) без механических подвижных транспортирующих устройств, сокращающий энергопотребление, эксплуатационные затраты, снижающий требования к качеству свекловичной стружки. Результаты испытаний на экспериментальной установке показали более высокое качество диффузионного сока. Светлость сока оказалась намного выше по сравнению с соками, получаемыми в традиционных диффузионных аппаратах, а доброкачественность сока оказалась на 5% выше при сопоставимом содержании сухих веществ, что дает дополнительное количество произведенного сахара в год, позволяя ускорить возврат капиталовложений.

The pulsatile stimulation technique (near-wellbore area) is an effective method of hydroimpulsive well treatment in oil production. The results of testing a pilot sample of a mobile pulsation unit at injection wells are presented, with an increase in injection capacity 3-4 times and other positive effects (well pressure drop, chemical composition change). The obtained results confirm the effectiveness of pulsation effects and create the prerequisites for the development of complex energy-saving ways of oil well treatment.

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