Two-phase Loop Thermosyphon Research Articles

Compact boiling refrigerant-type cooling unit using multi-stacked radiator cores for automobiles

We have developed a new closed two-phase loop thermosyphon with multi-stacked radiator cores and a new flow controller which forms refrigerant circulation. The features are: (1) more compact and lighter weight than heat pipe cooling units, (2) cooling performance can be easily adjusted by the number of radiator cores according to heat dissipation quantity. © 2000 Scripta Technica, Heat Trans Asian Res, 29(8): 634–647, 2000

Boiling Refrigerant Type Panel Cooler. Refrigerant Circulation and Cooling Performance.

We have developed a new compact boiling refrigerant type panel cooler. It is a kind of closed two-phase loop thermosyphon constructed with heat exchanger cores for automobile air conditioning system. We confirmed higher performance of the natural refrigerant circulation type and tried to optimize the size of the refrigerant path in the boiling core by observing the internal refrigerant flow and successfully achieved much higher cooling performance.

A Closed Counter-Current Two-Phase Thermosyphon Loop of a Cold Neutron Source in HANARO Research Reactor

An experimental study was carried out to delineate the flow characteristics in a closed countescurrent two-phase thermo syphon with concentric tubes. This is to be installed in the HANARO research reactor as a part of a Cold Neutron Source(CNS). In the present investigation, experiments ata room temperature with Freon-II3 as a moderator were performed. Results show that, based on the magnitude of pressure fluctuation, the flow regimes could be divided into 4 distinct ones in the () plane, where represents the volume of the charged liquid and the heat load: a stable flow regime, an oscillatory flow regime, a restablized flow regime and a dryout flow regime. For >2.5l, the flow is stable at low . However, as increases, the flow becomes oscillatory and finally restablizes As increases, the oscillation amplitude decreases, reaching to the restablized flow region at low , and the liquid level in the moderator cell remains high. In the oscillatory flow regimes, for a fixed VI; the oscillating period of time varies with , having a minimum value at a certain value of . The heat load, where the oscillating period of time is minimum, decreases as increases.

COMPACT THERMOSYPHONS EMPLOYING MICROFABRICATED COMPONENTS

This report presents a study of microfabricated enhanced structures for enhancing the thermal performance of a two-phase thermosyphon loop. The structures used in this study have an array of channels and pores that make it highly porous. The structures were fabricated in silicon using wafer dicing, wet-chemical etching, and laser milling, and details are included in this report. The structures were employed inside the evaporator section of a thermosyphon loop for enhancing the boiling performance. Preliminary results show that the heat dissipation with these structures is at least three times better than that of a plain polished silicon surface, at a wall superheat of 30 degrees C. The results also indicate that increasing the channel width resulted in better thermal performance.

Design of a two-phase loop thermosyphon for telecommunications system (I)

Design of a two-phase loop thermosyphon for telecommunications system (I)

Erratum to: Design of a two-phase loop thermosyphon for telecommunications system (I)-experiments and visualization

Erratum to: Design of a two-phase loop thermosyphon for telecommunications system (I)-experiments and visualization

Erratum to: Design of a two-phase loop thermosyphon for telecommunications system (II)-analysis and simulation

Erratum to: Design of a two-phase loop thermosyphon for telecommunications system (II)-analysis and simulation

Design of a two-phase loop thermosyphon for telecommunications system (II)

Design of a two-phase loop thermosyphon for telecommunications system (II)

Design of a two-phase loop thermosyphon for telecommunications system (I)

A two-phase loop thermosyphon system is developed for the B-ISDN telecommunications system and its performance is evaluated both experimentally and by visualization techniques. The design of the thermosyphon system proposed is aimed to cool muliichip modules (VICM) upto heat flux of 8 W/cm 2 . The results indicate that in the loop thermosyphon system, cooling heat flux is capable of 12 W/cm 2 with two condensers under the forced convection cooling of the condenser section with acetone or FC-87 as the working fluid. The instability of the working fluid flow within the loop is observed using the visualization techniques and temperature fluctuation is stabilized with orifice insertion.

Design of a two-phase loop thermosyphon for telecommunications system (II)

A computer simulation is performed for a two-phase loop thermosyphon for the B-ISDN telecommunications. The aim of this code development is to provide capabilities to predict the affects of many variables on the performance of the proposed TLT system using different empirical correlations obtained from the literature for the evaporation and condensation, and the shape factors available. In the present study, the simulation code is based on the sectorial thermal resistance network built on the flow regimes of the two-phase flows involved. The nodal resistances are solved by the typical Gauss-Seidal iteration method. The code can predict whether the proposed design is possible based on the Hooding limit calculation of the system and its results are compared with the experimental results.

Cmopact Thermosyphon using Multi-stacked Radiator Cores for Automobile. Refrigerant Circulation and Cooling Performance.

A new closed two-phase loop thermosyphon with multi-stacked radiator cores and a new flow controller forming refrigerant circulation have been developed. When the temperature of the partition wall which separates the liquid return passage from boiling region of the refrigerant tank becomes extremely high, the refrigerant circulation is inhibited. The inhibition factor of the refrigerant circulation was clarified.

Compact Thermosyphon Using Refrigerant Flow Control. (Improvement of Heat Transfer Characteristics in the Cooling Unit with Multiple Power Modules Vertically Mounted)

In a compact closed two-phase loop thermosyphon which consists of a multiradiator and a refrigerant bath with multiple power modules mounted vertically, the heat radiation performance deteriorates as the refrigerant bath becomes thinner. We have found that this is because the return condensate is blocked by the back flow of the bubble in the return path when the heat load decreases and increases sharply. We have also improved the heat radiation performance by providing an adiabatic path between the boiling area and the return path.

Compact Boiling Refrigerant Type Cooling Unit Using Multi-Stacked Radiator Cores for Automobile. Comparison with Heat Pipe Type Cooling Unit.

We have developed a new closed two-phase loop thermosyphon with multi-stacked radiator cores and a new flow controller which forms refrigerant circulation. The features are ; (1) more compact and lighter weight than heat pipe cooling units. (2) cooling performance can be easily adjusted by the number of radiator cores according to heat dissipation quantity.

Compact Thermosyphon with Refrigerant Flow Control. Improvement of Heat Transfer Characteristics in the Cooling Unit with Multiple Power Modules Mounted Vertically.

In a compact closed two-phase loop thermosyphon which consists of a multi-radiator and a refrigerant bath with multiple power modules mounted vertically the heat radiation performance deteriorates as the refrigerant bath becomes thinner. We have found that this is because the return condensate is blocked by the backflow of the bubble in the return path when the heat load decreases and increases sharply. We have also improved the heat radiation performance by providing an adiabatic path between the boiling area and the return path.

95/05079 Performance of a heat-pipe based waste-heat recovery and utilisation system for a gas-turbine engine

The results of a modelling and simulation study on the combined performance of a power system are presented. The combined system comprises an industrial, simple-type gas-turbine engine and a heat-pipe-based waste-heat recovery and utilisation system, and the engine itself comprises an axial-flow compressor, tubular combustion chambers and an axial-flow turbine. A water-in-steel type two-phase thermosyphon loop extracts waste energy from the stack of the gas turbine and delivers it to the generator of an aqua-ammonia absorption chiller, to produce chilled water which cools ambient air via a cooling tunnel; the cooled air is fed to the intake of the gas turbine compressor. Net power output of the overall system, when utilising the water-in-steel heat-recovery system, is improved by 12% even when the inlet air to the turbine is cooled to a modest 20 °C; this is true for both the base load and 75% part-load operation. Considerably higher boosting of output power is possible if the inlet air is cooled to lower temperatures. One of the most striking findings of the modelling and simulation study is that the water-in-steel heat-recovery system is capable of producing considerably more cold air than is required by the gas-turbine engine. It is further concluded that the thermal efficiency of the engine does not deteriorate with rising ambient temperatures, as is the case in a system without the heat-recovery and utilisation system.

Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon

Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon

The Effect of Subcooling on the Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon

The Effect of Subcooling on the Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon

Flow and Heat Transfer Characteristics in a Closed-Type Two-Phase Loop Thermosyphon

Flow and Heat Transfer Characteristics in a Closed-Type Two-Phase Loop Thermosyphon

Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon

Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon