Aluminum two-phase heat transfer systems with steam and liquid separation for energy efficient technologies

Comparison of designs of heat exchangers with smooth-walled aluminum grooved heat pipes (AGHP) with a diameter of 8 mm and finned AGHP with an outer diameter of 43 mm. The use of smooth-walled AGHPs, on the one hand, results in a larger number of them in the heat exchanger compared to the finned AGHPs, but, on the other hand, results in a smaller pressure drop in the channels. On the basis of the experimental data, dependences were obtained for the calculation of the coefficients of heat exchange and aerodynamic resistance for a heat exchanger with smooth-walled AGHPs.
Schematic solutions for the construction of cooling systems for LED lighting using AGHP are presented. The results of experimental studies of different AGHP models and cooling systems based on them showed:
a. the use of five AGHP lighting fixtures in the frame allows for a total heat flux of 500 W to be removed from the LED modules; when the efficiency of powerful LEDs is on average 75%, this is equivalent to the electric power consumed by the device, 665 W;
b. AGHP s with ammonia coolant can transmit thermal power of more than 250 watts; have a temperature difference of not more than 7°C at an electrical power of 200 W for each AGHP; at a power input of 40 W, the temperature difference is reduced to 2,5°C;
c. when used in the construction of AGHP as a radiator (type "steam chamber") as a pentane coolant, the operation of the cooling system in the vertical position is characterized by the minimum characteristics of the temperature difference between the zones of supply and heat dissipation; in steady state, this difference is 2 ± 0.5°C; AGHP cooling lamp meets the requirements for the LED operating temperature with a total thermal output of 196 W; this cooling system has a substantial margin over the permissible temperature, both for vertical positions (up to 15°C) and at an angle of 45° to the horizon (up to 10°C).
Schematic solutions of the application of AGHP in the systems of providing thermal modes of electronic equipment are given. Examples and results of experimental studies of different ACPT structures for different conditions of their application are given. Such AGHPs can operate in the temperature range from –40°C to + 210°C and provide heat transfer of more than 250W per AGHP.