Facilitated Diffusion of Carbon-Dioxide in a Living Body Liquid Film

A numerical study is performed for the facilitated diffusion of carbon-dioxide in an ultrapure water film flowing downward along a vertical surface. The model adopted for the present work includes the effects of the reaction rate for the hydration of CO(2)in a liquid. Comparison of the total concentration of CO(2) for different film thickness indicates that the effects of the hydration is more remarkable for the thinner liquid film

Freezing of Quiescent Water in a Horizontal Cylinder

Heat transfer measurements were conducted during freezing of quiescent water in a horizontal cylinder. A horizontal cylinder with inner diameter of 61.1 mm is cooled by air in a constant low temperature room and time variations of the radial distribution of fluid temperature were observed. Experimental results for the velocity of the phase change interface, the time taken for complete freezing and apparent freezing heat transfer coefficient were compared with the simple theoretical model based on the quasisteady assumption

Altered rectal sensory response induced by balloon distention in patients with functional abdominal pain syndrome

<p>Abstract</p> <p>Background</p> <p>Functional abdominal pain syndrome (FAPS) has chronic unexplained abdominal pain and is similar to the psychiatric diagnosis of somatoform pain disorder. A patient with irritable bowel syndrome (IBS) also has chronic unexplained abdominal pain, and rectal hypersensitivity is observed in a majority of the patients. However, no reports have evaluated the visceral sensory function of FAPS precisely. We aimed to test the hypothesis that FAPS would show altered visceral sensation compared to healthy controls or IBS. The present study determined the rectal perceptual threshold, intensity of sensation using visual analogue scale (VAS), and rectal compliance in response to rectal balloon distention by a barostat in FAPS, IBS, and healthy controls.</p> <p>Methods</p> <p>First, the ramp distention of 40 ml/min was induced and the thresholds of discomfort, pain, and maximum tolerance (mmHg) were measured. Next, three phasic distentions (60-sec duration separated by 30-sec intervals) of 10, 15 and 20 mmHg were randomly loaded. The subjects were asked to mark the VAS in reference to subjective intensity of sensation immediately after each distention. A pressure-volume relationship was determined by plotting corresponding pressures and volumes during ramp distention, and the compliance was calculated over the linear part of the curve by calculating from the slope of the curve using simple regression.</p> <p>Results</p> <p>Rectal thresholds were significantly reduced in IBS but not in FAPS. The VAS ratings of intensity induced by phasic distention (around the discomfort threshold of the controls) were increased in IBS but significantly decreased in FAPS. Rectal compliance was reduced in IBS but not in FAPS.</p> <p>Conclusion</p> <p>An inconsistency of visceral sensitivity between lower and higher pressure distention might be a key feature for understanding the pathogenesis of FAPS.</p

Radiative Characteristics of Frost Layer in Frosting and Defrosting Processes

Radiative characteristics of the frost layer melted by radiative heat are experimentally examined. A frost layer is heated from above by the radiative heat from a halogen lamp set. Thermal radiation of the lamp has the wavelength spectrum characteristics similar to those of the solar radiation. The effect of the environmental temperature upon the frost melting process is clarified in experiments. The optical characteristics of reflectivity, absorptivity and transmissivity of the frost layer during the melting of the frost layer are measured using special measuring instruments

National Survey on Youth Risk Behaviors and Resilience in Japan

科学研究費助成事業(科学研究費補助金)研究成果報告書：基盤研究(C)2010-2012課題番号：2250062

Experimental Study of Condensation Heat Transfer from Downward-Facing Inclined Surfaces

Experiments were perfomed to study the effect of surface inclination on condensation heat transfer from downward-facing horizontal surfaces. A smooth surface and two low-finned surfaces with a length of 50mm were tested for condensation of R-113. The angle of inclination from the horizontal φ ranged from 0 to 90 deg. For the smooth surface, the heat tranfer coefficient α first decreased with the increasing of φ, then took a minimum near 5 deg, and then increased monotonically with further increasing φ. For the low-finned surfaces, α increased sharply with φ in the range of 0 to 30 deg, and then increased moderately with further increasing φ. The heat tranpfer coefficient for the better performing finned surface was 2.5, 9 and 12 times the smooth surface value for φ=0, 10 and 90 deg., respectively.電子素子の発熱密度の増大にともない、高性能の冷却法として浸漬冷却に対する関心が高まり、研究が盛んになっている。この冷却法では、発生蒸気を凝縮させるための凝縮器が必要となる。その形式として種々のものが検討されているが、容器の上面または側面を凝縮器として使用するものが最も簡便な方式であると考えられる。著者らはさきに下向き水平凝縮面下部に蒸気空間が存在する場合および凝縮面が液中に浸漬されている場合の熱伝達特性とその促進法について実験的に検討し、多孔質排液板を取付けたフィン付き面を使用することによって熱伝達が平滑面に比べて大幅に促進されることを見いだした。これは、フィン間溝部に充満した凝縮液が毛細管力によって効率良く多孔質排液板へ引き込まれ、フィン頂部が高性能の凝縮面として働くためである。同様の排液効果は伝熱面を傾斜させ、重力を利用することによっても期待できる。本報では平滑面と2種類のローフィン付き面をとりあげ、下向き面上の凝縮熱伝達に及ぼす伝熱面傾斜角の影響を冷媒R113を用いて実験的に検討する

Condensation of Nonazeotropic Refrigerant Mixture R114/R113 in Horizontal Annuli with an Enhanced Inner Tube : Experimental Results

Local heat transfer and pressure drop measurements were made during condensation of a nonazeotropic refrigerant mixture R114/R113 in the annuli of horizontal double-tube condensers. The inner tube was a 19.1mm o.d. corrugated copper tube with soldered wire fins on the outer surface. The outer tubes were smooth tubes with inside diameter D_i of 29.9 and 25.0mm. The pressure drop and the heat transfer coefficient based on the bulk vapor-to-wall temperature difference were considerably smaller for R114/R113 than for R113. The vapor phase mass transfer coefficient β_n was higher for larger test fluid mass velocity G and D_i. At constant values of G and D_i, β_n was higher for larger condensation mass flux. The radial distribution of the vapor temperature was affected by the vapor velocity, becoming flatter at the outer part of the annulus and steeper near the liquid-vapor interface as the vapor velocity increased.蒸気圧縮式ヒートポンプ、冷凍機などの成績係数を向上させるための一方策としてローレンツサイクルが提案され、このサイクルに近づけることのできる非共沸2成分混合冷媒が実用されつつある。しかし、この冷媒が凝縮する際には低沸点蒸気が不凝縮ガスと類似の挙動を示すため、凝縮伝熱性能が単成分蒸気に比べて低下する。したがって、この冷媒を用いる凝縮器の性能向上を図るためには、凝縮液膜の熱抵抗と混合気の拡散抵抗の両者を減少させる必要がある。著者らは前提で純冷媒用の伝熱促進管の一種であるワイヤフィン付きコルゲート管を内管とする水平二重管環状部における非共沸混合冷媒R114/R113の凝縮実験を行い、圧力降下の摩擦成分は純冷媒に対する実験式で整理できること、凝縮側の熱抵抗にしめる気相の熱抵抗の割合は冷媒流量の増大につれて減少することを示した。そして、混合気相の物質伝達係数を円管上の強制対流凝縮理論から導かれた無次元パラメータを用いて整理した。しかし、より一般性のある整理式を得るためにはフィン形状、内外管径比などの影響を明らかにする必要がある。なお、フロン系非共沸2成分混合冷媒の管内、シェル側あるいは環状部における凝縮については最近多くの実験的研究が報告されているが、混合気相の物質伝達について検討したものは少なく、実験データの蓄積が望まれる。本報では、前報の内管とフィン配列が多少異なる管を内管とし、内径の異なる2種類の平滑管を外管とする水平二重管環状部におけるR114/R113の凝縮実験を行い、前報の結果と比較する。また、混合気相の温度分布測定結果についても述べる