TEMPERATURE TRANSITIONAL PHENOMENA IN SPHERICAL RESERVOIR WALL

Uneven and non-stationary temperature field is formed in the reservoir wall while loading pressure reservoir with a liquefied gas in cooling state, at a temperature lower than the saturation temperature at given pressure. Mathematical model of the temperature field is developed by setting and solving differential equation of heat diffusion in the spherical wall in real conditions of the wall getting cold. The model enables computation of the temperature gradient attaining very high values at the liquid level. A simplified procedure for calculating the wall temperature increase in the narrow area above the liquid level was also developed. Understanding of the temperature field in the reservoir wall allows further heat stresses calculation. For this purpose, a temperature discontinuity should be approximated by a continuous function. Approximation was applied by Fourier's orders, and coefficients of an order are determined by the electronic computer program. The model application procedure has been illustrated by the example of spherical pressure reservoir for liquefied carbon dioxide.Original Abstract: Tijekom punjenja tlacnog spremnika ukapljenim plinom, pothladenim ispod temperature zasidenja za zadani tlak, nastaje u stijenci spremnika nejednoliko i nestacionarno temperaturno polje. Matematicki model temperaturnog polja razvijen je postavljanjem i rjesavanjem diferencijalne jednadzbe provodenja topline u sfernoj stijenci u realnim uvjetima ohladrvanja stijenke. Model omogucava izracunavanje temperaturnog gradijenta koji na visini razine kapljevine poprima vrlo visoke vrijednosti. Razvijen je takoder i pojednostavljeni postupak za izracunavanje iznosaporasta temperature stijenke u uskom podrucju iznad razine kapljevine. Poznavanje temperaturnog polja u stijenci spremnika omogucava dalje izracunavanje toplinskih naprezanja. U tu svrhu diskontinuitet temperature treba aproksimirati kontinuiranom funkcijom. Primijenjena je aproksimacija pomocu Fourierovih redova, a koeficijenti reda se odredtiju pomocu programa za elektronicko racunalo. Postupak primjene modela ilustriran je na primjeru sfernog tlacnog spremnika za ukapljeni ugljini dioksid.