• Title/Summary/Keyword: Multi-port tube

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Flow Boiling Heat Transfer of R-22 in a Flat Extruded Aluminum Multi-Port Tube

  • Kim Nae-Hyun;Sim Yang-Sup;Min Chang-Keun
    • International Journal of Air-Conditioning and Refrigeration
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    • v.12 no.3
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    • pp.148-157
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    • 2004
  • Convective boiling heat transfer coefficients of R-22 were obtained in a flat extruded aluminum tube with $D_h=1.41mm$. The test range covered mass flux from 200 to $600kg/m^{2}s$, heat flux from 5 to $15kW/m^2$ and saturation temperature from $5^{\circ}C\;to\;15^{\circ}C$. The heat transfer coefficient curve shows a decreasing trend after a certain quality (critical quality). The critical quality decreases as the heat flux increases, and as the mass flux decreases. The early dryout at a high heat flux results in a unique 'cross-over' of the heat transfer coefficient curves. The heat transfer coefficient increases as the mass flux increases. At a low quality region, however, the effect of mass flux is not prominent. The heat transfer coefficient increases as the saturation temperature increases. The effect of saturation temperature, however, diminishes as the heat flux decreases. Both the Shah and the Kandlikar correlations un-derpredict the low mass flux and overpredict the high mass flux data.

Outcomes of Single-Incision Thoracoscopic Surgery Using the Spinal Needle Anchoring Technique for Primary Spontaneous Pneumothorax

  • Lee, Seung Hyong;Lee, Sun-Geun;Cho, Sang-Ho;Song, Jae Won;Kim, Dae Hyun
    • Journal of Chest Surgery
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    • v.55 no.1
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    • pp.44-48
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    • 2022
  • Background: Although classical multi-port video-assisted thoracic surgery has been widely performed, single-incision thoracoscopic surgery (SITS) is a popular surgical technique for the treatment of primary spontaneous pneumothorax (PSP). However, the inconvenient alignment of instruments and the limited field of view occasionally make surgeons convert from SITS to multi-port surgery or extend the incision. This study aimed to present an easy and safe SITS technique for PSP using a spinal needle. Methods: In total, 139 patients underwent SITS between May 2011 and December 2017. We used a spinal needle to hook the bulla or bleb, and wedge resection was performed through a small incision. Patients' medical records were reviewed retrospectively, and a telephone survey was conducted to investigate the recurrence rate. Results: The mean age of the 139 patients was 23.62±9.60 years. The mean operative time was 36.69±14.64 minutes, and multi-port conversion was not performed. The mean postoperative hospital stay was 3.00±0.78 days, and the mean indwelling chest tube duration was 1.97±0.77 days. No complications were observed. In the mean follow-up period of 86.75±23.20 months, recurrence of pneumothorax was found in 3 patients. Conclusion: We suggest that SITS for PSP with the aid of a spinal needle to replace a grasper is a safe and easy technique that only requires a small incision.

Efficacy of Single-Port Video-Assisted Thoracoscopic Surgery Lobectomy Compared with Triple-Port VATS by Propensity Score Matching

  • Song, Kyung Sub;Park, Chang Kwon;Kim, Jae Bum
    • Journal of Chest Surgery
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    • v.50 no.5
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    • pp.339-345
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    • 2017
  • Background: In recent years, single-port video-assisted thoracoscopic surgery (VATS) for lobectomy in non-small cell lung cancer (NSCLC) patients has become increasingly common. The objective of this study was to compare the feasibility and safety of single-port and triple-port VATS lobectomy. Methods: A total of 73 patients with NSCLC who underwent VATS lobectomy from December 2011 to August 2016 were retrospectively reviewed, including 47 in the triple-port group and 26 in the single-port group. Statistical analysis was performed after propensity score matching. Patients were matched on a 1-to-1 basis. Results: Operative time and intraoperative blood loss in the triple-port group and the single-port group were similar ($189.4{\pm}50.8minutes$ vs. $205.4{\pm}50.6minutes$, p=0.259; $286.5{\pm}531.0mL$ vs. $314.6{\pm}513.1mL$, p=0.813). There were no cases of morbidity or mortality. No significant differences in complications or the total number of dissected lymph nodes were found between the 2 groups. In the single-port group, more mediastinal lymph nodes were dissected than in the triple-port group ($1.7{\pm}0.6$ vs. $1.2{\pm}0.5$, p=0.011). Both groups had 1 patient with bronchopleural fistula. Chest tube duration and postoperative hospital stay were shorter in the single-port group than in the triple-port group ($8.7{\pm}5.1days$ vs. $6.2{\pm}6.6days$, p=0.130; $11.7{\pm}6.1days$ vs. $9.5{\pm}6.4days$, p=0.226). However, the differences were not statistically significant. In the single-port group, the rate of conversion to multi-port VATS lobectomy was 11.5% (3 of 26). The rates of conversion to open thoracotomy in the triple-port and single-port groups were 7.7% and 3.8%, respectively (p=1.000). Conclusion: In comparison with the triple-port group, single-port VATS lobectomy showed similar results in safety and efficacy, indicating that single-port VATS lobectomy is a feasible and safe option for lung cancer patients.

Feasibility and Safety of Single-Port Video-Assisted Thoracic Surgery for Primary Lung Cancer

  • Heo, Woon;Kang, Do Kyun;Min, Ho-ki;Jun, Hee Jae;Hwang, Youn-Ho
    • Journal of Chest Surgery
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    • v.50 no.3
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    • pp.190-196
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    • 2017
  • Background: The feasibility of single-port video-assisted thoracic surgery (SPVATS) for primary lung cancer is not well understood. In this study, we compared SP and multi-port (MP) VATS for the surgical treatment of patients with primary lung cancer. Methods: Surgical treatment was performed in 181 patients with primary lung cancer at Inje University Haeundae Paik Hospital between June 2012 and December 2015. A propensity-matched analysis was used to compare the postoperative outcomes and to evaluate the comparative feasibility and safety of SPVATS and MPVATS. Results: There were 37 patients in the SPVATS group and 67 patients in the MPVATS group. Propensity matching produced 32 pairs. The operation time (210 minutes versus 200 minutes, p=0.11), volume of the estimated blood loss (170 mL versus 160 mL, p=0.19), duration of chest tube drainage (5 days versus 6 days, p=0.66), and length of hospital stay (9 days versus 10 days, p=0.89) were similar between the 2 groups. Conclusion: In our study, SPVATS for primary lung cancer was safe and feasible in well selected patients. A prospective, randomized study with a large group and long-term follow-up is necessary to evaluate the clinical feasibility and the advantages of SPVATS for primary lung cancer.

Effects of die cooling on change of extrusion characteristics of Al-Mn-based thin-walled flat multi-port tube (금형 냉각이 Al-Mn계 다중압출 평판관의 압출 특성 변화에 미치는 영향)

  • Young-Chul Shin;Seong-Ho Ha;Tae-Hoon Kang;Kee-Ahn Lee;Seung-Chul Lee
    • Design & Manufacturing
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    • v.17 no.4
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    • pp.63-71
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    • 2023
  • In order to increase the extrusion production speed of aluminum, extrusion die cooling technology using liquid nitrogen has recently attracted a lot of attention. Increasing the extrusion speed increases the temperature of the bearing area of extrusion dies and the extrusion profile, which may cause defects on the surface of extruded profile. Extrusion die cooling technology is to directly inject liquid nitrogen through a cooling channel formed between the die and the backer inside the die-set. The liquid nitrogen removes heat from the die-set, and gaseous nitrogen at the exit of the channel, covers the extrusion profile of an inert atmosphere reducing the oxidation and the profile temperature. The aim of this study is to evaluate the cooling capacity by applying die cooling to extrusion of Al-Mn-based aluminum alloy flat tubes, and to investigate the effects of die cooling on the change in extrusion characteristics of flat tubes. Cooling capacity was confirmed by observing the temperature change of the extrusion profile depending on whether or not die cooling is applied. To observe changes in material characteristics due to die cooling, surface observation is conducted and microstructure and precipitate analysis are performed by FE-SEM on the surface and longitudinal cross section of the extruded flat tubes.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.