Development of Heated Narrow Channels with Enhanced Liquid Supply in Forced Convective Boiling

Abstract Heat generation density from semiconductor devices increases with the rapid development of electronic technology. The cooling system using boiling two-phase phenomena attracts much attention because of its high heat removal potential. Most of heat transfer researches concerning the development of electronic devices are conducted for the cooling of small semiconductor chips, while there are limited numbers of innovative investigations for the cooling of a large area at extremely high heat flux larger than 2×10 6 W/m 2 . The technology can be applied to the cooling systems in space, e.g., cooling of laser medium in solar power satellites when solar energy is converted to laser power. To develop compact and high-performance cooling systems, a structure of narrow heated channel between parallel plates with auxiliary unheated channel was devised and tested by using water in three different kinds of experimental conditions. One of liquid supply method, where liquid is supplied to both of the main heated and the auxiliary unheated channel keeping the exit of the auxiliary channel closed, gives the highest CHF value at total volumetric flow rates more than 3.0×10 -5 m 3 /s and 2mm gap size of main heated channel

Metal cations modulate the bacteriochlorophyll–protein interaction in the light-harvesting 1 core complex from Thermochromatium tepidum

AbstractThe light-harvesting 1 reaction center (LH1-RC) complex from Thermochromatium (Tch.) tepidum exhibits unusual Qy absorption by LH1 bacteriochlorophyll-a (BChl-a) molecules at 915nm, and the transition energy is finely modulated by the binding of metal cations to the LH1 polypeptides. Here, we demonstrate the metal-dependent interactions between BChl-a and the polypeptides within the intact LH1-RC complexes by near-infrared Raman spectroscopy. The wild-type LH1-RC (B915) exhibited Raman bands for the C3-acetyl and C13-keto CO stretching modes at 1637 and 1675cm−1, respectively. The corresponding bands appeared at 1643 and 1673cm−1 when Ca2+ was biosynthetically replaced with Sr2+ (B888) or at 1647 and 1669cm−1 in the mesophilic counterpart, Allochromatium vinosum. These results indicate the significant difference in the BChl–polypeptide interactions between B915 and B888 and between B915 and the mesophilic counterpart. The removal of the original metal cations from B915 and B888 resulted in marked band shifts of the C3-acetyl/C13-carbonyl νCO modes to ~1645/~1670cm−1, supporting a model in which the metal cations are involved in the fine-tuning of the hydrogen bonding between the BChl-a and LH1-polypeptides. Interestingly, the interaction modes were almost identical between the Ca2+-depleted B915 and Sr2+-depleted B888 and between B915 and Ca2+-substituted B888, despite the significant differences in their LH1 Qy peak positions and the denaturing temperatures, as revealed by differential scanning calorimetry. These results suggest that not only the BChl–polypeptide interactions but some structural origin may be involved in the unusual Qy red-shift and the enhanced thermal stability of the LH1-RC complexes from Tch. tepidum