Heat transfer in the evaporation channels of film evaporators
Вантажиться...
Дата
2013
ORCID
DOI
Науковий ступінь
Рівень дисертації
Шифр та назва спеціальності
Рада захисту
Установа захисту
Науковий керівник
Члени комітету
Видавець
Анотація
There is an urgent need in the reliable correlation allowing calculation of heat transfer coefficients to highly concentrated films boiling at vacuum, which refers to the operational regimes of vacuum pans of multistage evaporators in the sugar industry. According to the stated objective, a rigorous study into thermo - and hydrodynamic parameters of film flows has been carried out. For this purpose a special experimental rig aimed at the modeling of two - phase flows with independent phases’ flow rates formation has been developed and erected.
Experimentation enveloped the regimes of evaporation free interphase surface as well as boiling at forced convection in down falling liquid films of sugar solutions within a wide range of concentrations at atmospheric pressure and vacuum. The solution mass concentration range d within 0…72%.
Analysis of the obtained data has proven, firstly, that the resultant of correlation may be based on the idea of the inter – phase turbulence suppression.
Secondly, experimental data showed that the simple criteria of the onset of the nuclear boiling in – films could be formed with the limiting condition of the steam phase appearing: which is overheating of the heat transfer surface with the given roughness of it.
The resultant equation which can be used for the calculations of heat transfer coefficients to the saturated gravitational falling films in pipes is derived. This equation can be used equally within the regime of evaporation from the interphase as well as within the regime of nucleate boiling at forced convection.
Опис
Ключові слова
gravitational descending films, sugar solutions, forced convection, multistage evaporator, vacuum, гравітаційно-стікаючі плівки, цукрові розчини, вимушена конвекція, випарна установка, кафедра теплоенергетики та холодильної техніки
Бібліографічний опис
Riabchuk, O. Heat Transfer to the falling viscous films of sugar solutions / O. Riabchuk, V. Petrenko // NEEFood-2013 : Second North and East European Congress on Food, 26-29 May 2013 : book of abstract - St. Kyiv, 2013. – P. 9.