An experimental study of the condensation of pure and mixed refrigerants of R22 and R114 inside a spirally grooved horizontal copper tube has been carried out. A double-tube counterflow condenser in the pressure range 3–21 bar and at a mass flow-rate 26–70 kg h −1 was used. The axial distributions of refrigerant, tube wall and cooling water temperatures, wall heat flux density and vapour quality are shown graphically. The variation of tube wall temperature around the circumference of the tube is also shown. The local Nusselt number depends on the molar fraction, whereas the average Nusselt number can be correlated by an equation which is modified from a previously established equation for pure refrigerants inside a horizontal smooth tube. The frictional pressure drop evaluated is correlated well by the Lockhart-Martinelli parameters and is independent of the concentration of the mixture.

Condensation heat transfer of binary refrigerant mixtures of R22 and R114 inside a horizontal tube with internal spiral grooves

Heat transfer performance during condensation of R-134a inside helicoidal tubes

Pool boiling of R-134a and R-123 on smooth and enhanced tubes

Local heat transfer coefficient for pool boiling of R-134a and R-123 on smooth and enhanced tubes

Condensation of Nonazeotropic Binary Refrigerant Mixtures Including R22 as a More Volatile Component Inside a Horizontal Tube

Complete condensation of nonazeotropic binary mixtures of R11-R113 refrigerants is experimentally studied. The test apparatus consists of two concentric horizontal tubes, with the vapor mixture flowing in the inner tube and the cooling water in the annular space in the countercurrent direction. The composition and the mass flow rate of the binary-component mixture are systematically varied. Through the measurement of the local temperature of the wall, the cooling water and the vapor along the tube axis, the axial distribution of the local heat transfer coefficients are obtained. An empirical equation is derived to correlate condensation heat transfer performance.

非共沸2成分混合蒸気の水平管内凝縮熱伝達 : r113+r11の場合

In this paper, molecular simulations using a genetic algorithm are conducted to investigate the stability of deposited atoms on a substrate. First, to confirm the validity of the method, the stability of structures of L-J clusters is studied and it is successfully shown that a stable 13-atoms cluster has a well-known icosahedral structure. Then using this method, the stability of structures of deposited atoms on a solid surface is investigated. The results show that deposited atoms have either an island or a layer structure, depending on the combination of intermolecular potentials of the deposited atom and the substrate atom. Furthermore, to apply the method for systems having a certain temperature, a new method using a modified intermolecular potential is proposed. The results of the advanced simulation agree qualitatively with those of the MD simulation. Although the GA simulation gives good results, it also requires much less CPU time than MD simulation. Therefore, it can be concluded that the GA simulation is a superior technique for examining stable structures of many-particle systems.

遺伝的アルゴリズムを用いた薄膜の安定構造解析 ( マイクロスケールの流体・熱流動現象)

An experimental study on microscopic scale measurements of thermal expansion and temperature by using the Scanning Joule Expansion Microscope (SJEM) based on the Atomic Force Microscope (AFM) was conducted. While the AFM is scanning on the sample heated by AC current, topographical and thermal expansion images are measured simultaneously by detecting DC and AC motions of the cantilever. In order to apply this technique to the temperature measurement in microscopicscale, the sample was covered with a thin film of polymer (PMMA) which has a high thermal expansion coefficient compared with metals and dielectric materials. Merits of this technique are (1) quite simplicity of measurement because of using the commercial cantilever instead of complicated thermal cantilever for the typical Scanning Thermal Microscopy (SThM) and (2) a higher spatial resolution of 20 nm which is restricted by the point contact scale between the cantilever and the sample.

井上剛良

Papers

非共沸2成分混合蒸気の水平管内凝縮熱伝達 : r113+r11の場合

遺伝的アルゴリズムを用いた薄膜の安定構造解析 ( マイクロスケールの流体・熱流動現象)

原子間力顕微鏡を用いた微小スケール熱膨張・温度計測 ( マイクロスケールの流体・熱流動現象)

井上 剛良

Papers

非共沸2成分混合蒸気の水平管内凝縮熱伝達 : r113+r11の場合

遺伝的アルゴリズムを用いた薄膜の安定構造解析 ( マイクロスケールの流体・熱流動現象)

原子間力顕微鏡を用いた微小スケール熱膨張・温度計測 ( マイクロスケールの流体・熱流動現象)

井上剛良