20.500.12556/RUL-125698 An experimental heat-transfer study for a heat-recovery unit made of corrugated tubes This paper presents a study of the thermal characteristics of a concentric-tube heat exchanger that is a key element in local ventilation device. The inner tube of the concentric-tube heat exchanger has a sinusoidal, wavy surface in the longitudinal direction, which enables heat-transfer enhancement. The tube can be stretched to a certain extent and thus change the corrugation of the heat-transfer surface area. We designed an experiment in which we used the Wilson-plot method to separately determine the convective heat-transfer coefficient on the inside and outside of the inner tube of the concentric-tube heat exchanger with different corrugation ratios. Based on the measurements correlation equations were developed to calculate the convective heat-transfer coefficient for any corrugation ratio, which allows us to simplify the design of local ventilation devices. Performed studies showed that, compared to a smooth tube, the convective heat-transfer coefficient increased only in the case of corrugated tubes with a corrugation ratio of less than 1.648, but the heat transfer was more intense for all considered corrugated tubes by 65-90% due to the increased heat-transfer surface area. The highest heat-transfer rate was observed for the case of the maximum-stretched tube with a corrugation ratio of 1.401, which is advantageous also in terms of material consumption. convective heat-transfer coefficient corrugated tubes Wilson-plot method heat exchanger koeficient toplotne prestopnosti Wilsonova metoda prenosnik toplote orebrene cevi true false true Angleški jezik Slovenski jezik Članek v reviji 2021-04-02 11:10:01 2021-04-02 11:10:06 2022-09-05 03:52:08 0000-00-00 00:00:00 2013 0 0 Str. 49-56 iss. 1 Vol. 53 2013 0000-00-00 PostprintKoncna Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 2015-01-19 697:628.8 1359-4311 10.1016/j.applthermaleng.2013.01.004 12647963 1861910 RAZ_Poredos_Primoz_2013.pdf RAZ_Poredos_Primoz_2013.pdf 1 7A0D2C26EE6CEB1F34E8C1859214F629 60efcec6429aec480e10020ca79a92b07d097224a51ebdd779a15ded38676933 c56ca9f8-a1bb-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=141548 https://doi.org/10.1016/j.applthermaleng.2013.01.004 1 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=141547 Fakulteta za strojništvo 0 0 0