Author(s):
1. Danijela Kardaš, Mašinski fakultet Univerziteta u Banjoj Luci, Republic of Srpska, Bosnia and Herzegovina

Abstract:
The concept of two-phase flow refers to the flow of the mixture of one or more component, where in the system are two phases. The complexity of these flows is a consequence of the appearance of the flow between the phases. Additional complexity appears in the process of the heat exchange because the phase image of two-phase flow changes. In vertical evaporators there are typical four zones in the process of evaporation, which differ in the flow regime and heat exchange mechanism. Evaporation represent two-phase flow with heat exchange. Circulation two-phase mixture in the evaporator with natural circulation (thermosiphon evaporators) is achieved due to the density difference between fluid and peri-liquid mixtures. Because of his good qualities, and because of the low exploitation costs, thermosiphon evaporators are very widespread. Although they are not suitable for the treatment of highly viscous fluids and to work at pressures lower than 0.3 bar. The aim of this paper is to provide analyze one of the possible applications of the thermosiphon. It’s a case when vertical thermosiphon evaporate the liquid residue on the bottom of the distillation column. In the literature, there are different methods for analysis of fluid flow for these devices. This paper presents calculation two-phase pressure drop for evaporator with natural circulation using a homogeneous method, Lockhart–Martinelli method , Alexander\'s method and the method of Levin.

Key words:
two – phase flow, thermosiphon evaporators, pressure drop

Thematic field:
Termotehnika i energetika

Date of abstract submission:
28.02.2013.

Number of visits:
354

Conference:
DEMI 2013