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1

Flat polymer loop thermosyphons

Vasiliev L., Grakovich L., Rabetsky M., Zhuravlyov A., Vassiliev Jr. L.

Archives of Thermodynamics

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2018

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Vol. 39, no 1

75--90

EN

The flat horizontal polymer loop thermosyphon with flexible transport lines is suggested and tested. The thermosyphon envelope consists of a polyamide composite with carbon based high thermal conductive micro-, nanofilaments and nanoparticles to increase its effective thermal conductivity up to 11 W/(m°C). Rectangular capillary mini grooves inside the evaporator and condenser of thermosyphon are used as a mean of heat transfer enhancement. The tested working fluid is R600. Thermosyphon evaporator and condenser are similar in design, have a long service life. In this paper three different methods (transient, quasi-stationary, and stationary) have been used to determine the thermophysical properties of polymer composites used as an envelope of thermosyphon, which make it possible to design a wide range of new heat transfer equipment. The results obtained contribute to establish the viability of using polymer thermosyphons for ground heat sinks (solar energy storage), gas-liquid heat exchanger applications involving seawater and other corrosive fluids, efficient cooling of superconductive magnets impregnated with epoxy/carbon composites to prevent wire movement, enhance stability, and diminish heat generation.

2

Vapordynamic thermosyphon – heat transfer two-phase device for wide applications

Vasiliev L., Vasiliev L., Zhuravlyov A., Shapovalov A., Rodin A.

Archives of Thermodynamics

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2015

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Vol. 36, no. 4

65--76

EN

Vapordynamic thermosyphon (VDT) is an efficient heat transfer device. The two-phase flow generation and dynamic interaction between the liquid slugs and vapor bubbles in the annular minichannel of the VDT condenser are the main features of such thermosyphon, which allowed to increase its thermodynamic efficiency. VDT can transfer heat in horizontal position over a long distance. The condenser is nearly isothermal with the length of tens of meters. The VDT evaporators may have different forms. Some practical applications of VDT are considered.

3

Solid sorption cooler with composite sorbent bed and heat pipe thermal control

Vasiliev L., Tsitovich A., Zhuravlyov A., Antough A.

Polska Energetyka Słoneczna

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2012

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nr 1-4

12-18

EN

Three adsorbers cooler was experimentally investigated. Ammonia was chosen as a working fluid. Two adsorbers (twins) were filled with the same complex compound (activated carbon fibre with MnCl2 microcrystals on the filament surface). The third low temperature adsorber had second complex compound (activated carbon fibre with BaCl2 microcrystals on the filament surface). The cycle of physical adsorption and chemical reactions in the sorbent bed of adsorber was followed with condensation/evaporation of ammonia inside the pores of the sorbent material. The specific feature of the third adsorber is the time of its cold generation. It is the sum of the liquid evaporation time and the time of desorption/regeneration of ammonia in the sorbent bed. This is a novelty of cooler design, which increases the heat and cold generation capacity and rate. The cooler thermal management is based on vapordynamic thermosyphons. The solar heat is the source of energy of cooler. The sink of the cold is the air flow.

4

Propane pool boiling heat transfer on horizontal tube

Vasiliev L., Zhuravlyov A., Khrolenok V., Novikov M., Rak A., Mazyuk V.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

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1999

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Z. 67

339--347

EN

An experimental investigation of propane boiling heat transfer was done on single horizontal smooth tubes and tubes with porous coverings. Three modes of heat transfer were determined on evaporation surfaces with increasing heat flux: free convection, a transitional mode (the average vapor bubble population was negligible) and developed boiling. The existence of the region length depends on saturation pressure, the kind of evaporation surface, and the direction of heat flux change. On heat flux reduction, a strong heat-flux hysteresis phenomenon was observed: the picture regarding changes of heat transfer regimes the same, but boiling extended into the region which was occupied by free convection. In the wide range of saturation pressures and heat fluxes, the intensity of heat transfer on the samples with porous coatings is high than that on the smooth surface samples. The research carried out showed that an application of metal porous covering with electric arc gas-thermal spraying allows one to increase significantly (3-5 times as high in the region of low heat loads, q < 8 kW/m2, and 2.5-3 times in the region of high heat fluxes, q > 8 kW/m2) the heat transfer intensity for propane boiling on horizontal tubes.