http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 주제어 : 수직평판 (검색결과 39 건)
-
垂直平行平板 사이의 自然對流 熱傳達에 關한 實驗的 硏究
一定한 平板 溫度의 熱的 境界條件에서 서로 다른 온도를 갖는 두 垂直平行平板에 있어서 두 平板의 溫度差와 두 平板의 間隔의 變化에 따른 空氣에 대한 自然對流 熱傳達의 效果를 實驗的으로 測定하였다. 實驗의 結果로는 Rayleigh 數가 작을수록 흐름의 發展性이 빠르며 平板에서 放出 되는 熱量은 無次元 Channel 길이가 클수록 적고 구간 2×10²<Ra<5×10³에서 平均 Nusselt 數와 Rayleigh 數의 關係는 □= 0.658 □^0.246의 關係式을 갖는다. This paper experimentally measured the effect of natural convection heat transfer for air in accordance with changes of wall temperature difference ratio and channel width in vertical parallel plate channel with asymmetric heating under thermal boundary condition of uniform wall temperature. From experimental results, it is shown that the less Rayleigh number, the faster developing speed of flow, and the larger dimensionless channel length, the less heat flux, and relation between Nusselt number and Rayleigh number in 2 × 10² <Ra <5 x 10³ is Nu = 0.658 Ra^0.246.
-
The mixed convection heat transfer from two vertical plates with in-line, misaligned and parallel arrays are investigated numerically by using a finite difference method and experimentally with a Mach-Zehnder interferometer. Effects of the plate spacings, the temperature ratios, the length ratios, Grashof numbers and Reynolds numbers are studied. The following results can be drawn from the present study. 1. The thermal plume interaction shows greater effect in the order of parallel, misaligned, and in-line array and prominently enhances the convective heat transfer at Φ_(R)=1.0 and L_(R)=1.0. 2. For misaligned and parallel arrays, the optimum plate spacing becomes narrower as Reynolds number and the temperature ratio increase and the length ratio decreases. From these results, the optimum plate spacing at Gr=10^(4) can be expressed by the correlation equations as follows. Misaligned arrays B_(opt) =6.20 (Re)^(-0.512) (Φ_(R))^(-0.117) ( L_(R) = 1.0 ) B_(opt) =5.982 (Re)^(-0.507) (L_(R))^(0.213) ( Φ_(R) = 1.0 ) Parallel arrays B_(opt) =4.140 (Re)^(-0.512) (Φ_(R))^(-0.199) ( L_(R) = 1.0 ) B_(opt) =3.954 (Re)^(-0.519) (L_(R))^(0.420) ( Φ_(R) = 1.0 ) 3. Regardless of the temperature ratio and length ratio, the optimum plate spacing for the parallel array is narrower than that for the misaligned array, and is affected parameterically in the order of Reynolds number, the length ratio and the temperature ratio. 4. The total mean Nusselt numbers increase as Reynolds number and the temperature ratio increase. They also increase a s the length ratio decreases. From these results, the mean and maximum mean Nusselt numbers at Gr=10^(4) can be expressed by the correlation equations as follows. In-line arrays Nu￣_(10) = 1.50 (Re)^(0.32) ( L_(R) = 1.0, Φ_(R) = 1.0 ) Misaligned arrays Nu￣_(max) = 1.088 (Re)^(0.399)(Φ_(R))^(0.015) ( L_(R) = 1.0 ) Nu￣_(max) = 1.160 (Re)^(0.388)(L_(R))^(-0.227) ( Φ_(R) = 1.0 ) Parallel arrays Nu￣_(max) = 1.025 (Re)^(0.426)(Φ_(R))^(0.018) ( L_(R) = 1.0 ) Nu￣_(max) = 1.092 (Re)^(0.411)(L_(R))^(-0.233) ( Φ_(R) = 1.0 ) 5. Regardless of the temperature ratio and the length ratio, the total mean Nusselt numbers are larger in the order of parallel array, misaligned array, and in-line array, and is affected parameterically in the order of Reynolds number, the length ratio and the temperature ratio. 6. A comparison between the experimental results and the numerical results shows qualitatively good agreement.
-
-
-
-
수직평판 젖은 벽탑에서 ethanol의 증발에 따른 열 및 물질이동 속도를 측정하였다. 공기는 수직평판을 따라 흘러내리는 ethanol의 유하액막을 따라 향류로 층류경계층을 형성한다. 액막이 공기의 경계층에 영향을 미치지 않는다고 가정할때 ethanol의 증발에 의한 열 및 물질 이동속도에 공기와 액체의 유속 및 온도등이 미치는 영향을 실험적으로 연구하였다. 공기의 Reynolds수가 3000 이하의 적은 범위에서 공기의 온도와 액체의 유속은 물질이동 속도에 큰 영향을 미치지만 공기의 유속이 증가할수록 그 영향은 감소하였다. ethanol의 증발에 따른 물질이동 속도는 공기의 유속이 지배적이며 기상 Reynolds수의 0.6승에 비례한다. 또한, 열이동 속도는 층류경계층 이론에 의한 이론치와 잘 일치하였다. Heat and mass transfer rates with ethanol evaporation were measured in a vertical flat-plate wetted wall column. Air stream forms a countercurrent laminar boundary layer along the ethanol film flowing down a vertical flat-plate. It was assumed that the boundary layer of an air stream was not affected by the liquid film. The effect of liquid flow rate, air stream flow rate and temperature on the heat and mass transfer rates were experimentally studied using a laminar boundary layer theory. The mass transfer rate was much influenced by the air stream temperature and liquid flow rate in the low range of gas phase Reynolds number 3000 and less. But when the air stream flow rate was high, this effect was less important. Air stream flow rate was found to take a major role in mass transfer rate. Mass transfer rate was proportional to ReG^0.6. The heat transfer rate showed a good agreement with the laminar boundary layer theory.
-
干涉計를 利用한 垂直平板핀이 附着된 水平圓筒에서의 自然對流 熱傳達에 대한 硏究
This interferometric study on the natural convection has been studied experimentally for a bare cylinder, a horizontal circular cylinder with a downward projecting fin, and cylinder with upward and downward projecting fins. The experiment was conducted under the conditions of laminar flow and steady state for various Rayleigh numbers in the air. The experimental results are as follows; 1) As increasing the Rayleigh numbers, the heat transfer rate from the cylinder surface was increased and well agreed with the theoretical result(Ra=10^(4)) of T. H. Kuehn for bare cylinder. 2) In case ofθ=170˚, dimensionless temperature distributions versus dimensionless distance from the surface of bare cylinder was higher than circular cylinder with fin. 3) Mean Nusselt numbers of bare cylinder was much larger than cylinder with fin for the same Rayleigh numbers. 4) In case of cylinder with upward and downward projecting fins, the temperature gradient was very small between fin tip and fin base for upper fin, and it was not affected almostly in heat transfer for upper fin. This interferometric study on the natural convection has been studied experimentally for a bare cylinder, a horizontal circular cylinder with a downward projecting fin, and cylinder with upward and downward projecting fins. The experiment was conducted under the conditions of laminar flow arid steady state for various Rayleigh numbers in the air. The experimental results are as follows; 1) As increasing the Rayleigh numbers, the heat transfer rate from the cylinder surface was increased and well agreed with the theoretical result(Ra=10^(1)) of T.H.Kuehn for bare cylinder. 2) In case of θ=170˚, dimensionless temperature distributions versus dimensionless distance from the surface of bare cylinder was higher than circular cylinder with fin. 3) Mean Nusselt numbers of bare cylinder was much larger than cylinder with fin for the same Rayleigh numbers. 4) In case of cylinder with upward and downward projecting fins, the temperature gradient was very small between fin up and fin base for upper fin, aid it was not affected almostly in heat transfer for upper fin.
-
-
-
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
