Measurement of the performances of a transparent closed loop two-phase thermosyphon

Abstract

This paper presents measurements performed on a transparent gravity driven twophase loop. For this purpose a small channel thermosyphon was manufactured completely out of borosilicate glass and equipped with a 100 nm semi-transparent ITO layer as a direct current heating evaporator. Thus flow patterns could be observed in the evaporator and at the same time the total thermal resistance was calculated with the heater temperature. Influence of heat flux and filling ratio on the thermal resistance and pressure oscillations were investigated.

Compact Air-to-Air Thermosyphon Heat Exchanger

“…This model relies on the solving of the three conservation equations (mass, momentum, and energy) combined into a minimization algorithm in order to determine the mass flow rate, saturation temperature, and evaporator exit vapor quality inside the loop. This model and its validation are detailed by Agostini and co-workers [5][6][7][8][9]. In order to predict the performances of a stack of thermosyphons it is in theory possible to use this model for each single element of the stack, using the results of the element number n-1 as an input for the element number n. Unfortunately, this method proved to give bad results because the initial input has to be the inlet cold stream and outlet cold stream temperatures, which can have very close values when the heat exchanger effectiveness gets closer to 100% and therefore cause errors to propagate and amplify quickly to the other side of the stack.…”