Flow Boiling in Minigap in the Reversed Two-Phase Thermosiphon Loop

Abstract

The paper presents the results of experimental investigations of a model of a heat exchanger featuring a minigap, which is perceived as an evaporator for an inverted thermosiphon. The system works with a single component test fluid. The tested evaporator generates pumping power in the test loop in a way similar to the mammoth pump. The tests regarded a module of the heat exchanger, consisting of a hot leg and a cold leg with the width by the length of 0.1 × 0.2 m, heated by a uniform heat flux. In the tests, the minigaps of 1, 2 and 3 mm were formed. Two fluids, namely, distilled water and ethanol, were tested in the facility. Two-phase flow structures for both working fluids and various operational parameters, together with comprehensive visualization material, are presented. The specifics of pressure changes and its influence on operating parameters and flow structure are discussed.

A New Concept and a Test of a Bubble Pump System for Passive Heat Transport from Solar Collectors

“…The operating principle of a reverse thermosiphon with a vapor lift pump and one working medium is presented in Figure 5. Similar systems that are filled with one working medium and use a vapor lift pump to transfer heat downward have been analyzed by Ito et al [32], Yandri et al [33], and Klugmann et al [34].…”

Experimentally Verified Flow Distribution Model for a Composite Modelling System

“…Investigations into minigaps of different geometries (e.g., rectangular [21] or annular [22]) usually focus on the thermal performance (e.g., local heat transfer coefficients [23], Nusselt number [24], or temperature distribution [25]). Flow distribution in minigaps is discussed rarely, and if so, then usually as a side experimental observation [26] or in the form of numerical analyses using computational fluid dynamics (CFD) [27]. Several studies have also compared the performance of both mini-scale applications, i.e., minichannels and minigaps.…”