Utilization of the principle of corresponding states for determination of the heat transfer coefficient during nucleate boiling of pure substances

V delu obravnavamo proces mehurčkastega vrenja, ki vsled konvektivnega prenosa toplote ob kapljevito parni fazni spremembi spada med najbolj učinkovite inženirsko obvladljive mehanizme prenosa toplote. Za napoved koeficienta toplotne prestopnosti pri mehurčkastem vrenju čistih fluidov se zatekamo h korelacijskim modelom, ki delujejo na podlagi identifikacije ključnih spremenljivk procesa ter empirične določitve njihove vplivnosti, zato je njihova uporabnost omejena na specifične obratovalne pogoje. V tem desetletju se izjemno intenzivno eksperimentalno preučuje izboljšanje prenosa toplote pri mehurčkastem vrenju s pomočjo hidrofilno-hidrofobnega strukturiranja vrelnih površin, kjer dosegamo tudi večkratno povečanje koeficientov toplotne prestopnosti, a korelacij za popis izboljšanja še ni razvitih. V delu smo na podlagi v literaturi dostopnih izmerjenih vrednosti obravnavali koeficiente toplotne prestopnosti pri mehurčkastem vrenju različnih čistih fluidov v širokem temperaturnem in tlačnem območju ter izvedli primerjalno analizo pomembnejših empiričnih metod. Na osnovi pregleda referenčne literature smo tvorili bazo podatkov za 39 različnih čistih fluidov s 1326 izmerjenimi vrednostmi koeficientov toplotne prestopnosti. Preučili smo tudi možnost uporabe principa korespondenčnih stanj za določevanje koeficienta toplotne prestopnosti pri mehurčkastem vrenju čistih fluidov, kjer poleg poznavanja temperature potrebujemo le molsko maso, kritično temperaturo, kritični tlak, Pitzerjev acentrični faktor ter polarni parameter.In this work, we consider the process of nucleate boiling which is one of the most efficient and manageable heat transfer mechanisms due to the convective heat transfer during the liquid-vapour phase change. For numerical prediction of the heat transfer coefficient in nucleate boiling of pure fluids, we resort to correlation models which work by identification of key process variables and the empirical evaluation of their influence. Therefore, their applicability is limited to specific operating conditions. During this decade, a great emphasis was put on the subject of possible improvements heat transfer in nucleate boiling by hydrophilic-hydrophobic structuring of the boiling surfaces, which can offer a multiplicative increase in heat transfer coefficient in the process. However, correlations to characterize the improvements have not yet been developed. Based on available experimental data of heat transfer coefficients for nucleate boiling of different pure fluids over a wide temperature and pressure range, a comparative analysis of the most relevant empirical methods was carried out. Based on a review of the reference literature, we created a database for 39 different pure fluids with 1326 measured values of heat transfer coefficients. We also investigated the feasibility of using the correspondence states principle to determine the heat transfer coefficient in nucleate boiling of pure fluids where, in addition to knowing the temperature, we only need the molar mass, the critical temperature, the critical pressure, the Pitzer acentric factor, and the polar parameter of the fluid