Development and investigation of perspective miniature energy saving devices on based of evaporating - condensation cycle.
Analysis of literature sources had shown that up-to-date state of miniaturization of electronic devices needs the development of new small-size cooling systems, which are capable to reject great heat fluxes. Within the bounds of this problem theoretical ground of advisability of using miniature heat pipes, thermosyphones and oscillating heat pipes in cooling systems for a wide range of powerful elements of microelectronic technics was found. Mathematical model of heat transfer processes in conditions of decreasing inner space in thermosyphones, miniature and oscillating heat pipes was presented. Transfer from large space to small space is determined by the Bond number (Bo). There are some changes in heat transfer conditions when Во0,5 < 1 and, therefore, existing relations are inadequate for calculating heat transfer intensity in conditions of decreasing vapour space. For investigation of this process a couple of miniature heat pipes with outer diameter from 3 mm to 6 mm (inner diameter of vapour space – from 1,2 mm to 4 mm) were produced. Was shown, that decreasing of vapour space diameter results in great increasing of thermal resistance and decreasing of transferred heat fluxes. Visualisation of vapour generating processes was carried out on glass miniature thermosyphones and oscillating heat pipes. New data about dependence of pulsations of temperature in heat transfer zones from transferred heat flux were obtained due to such cinematographic investigation of hydraulic characteristics of liquid-vapor mixture flow in thermosyphones and oscillating heat pipes. As a result of heat transfer characteristic investigation new relations between heat transfer coefficients in heat transfer zones and heat flux were obtained at a first time. New data about maximum heat fluxes transferred by miniature heat pipes and thermosyphones were recovered. Criteria relations for calculating of heat transfer intensity in heating zones of miniature heat pipes and thermosyphones were determined. Analysis of vapor generating processes in conditions of miniaturization of cooling systems based on evaporating-condensation cycle was conducted.
Miniature heat pipe cooling system for central processor unit of powerful hermetical computer was created on base of conducted investigations. Prototype of oscillating heat pipe cooling system for central processor unit of computer was also produced. Methods of calculation of characteristics of miniature heat pipes and recommendations for creation of up-to-date cooling systems with high heat transfer behaviors are developed.