• Title/Summary/Keyword: cooling condition

Search Result 1,241, Processing Time 0.032 seconds

Performance Characteristics of Cooling Tower on Small Absorption Chiller (가정용 흡수식 냉온수기용 냉각탑의 성능특성)

  • Sarker M.M.A;Kim Eun-Pi;Jeong Seok-Kwon;Min Kyung-Hyun;Kim Jae-Dol;Yoon Jung-In
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.28 no.7
    • /
    • pp.1145-1151
    • /
    • 2004
  • The experiment of thermal performance about cross flow type cooling tower was conducted in this study. Generally the ambient air condition can affect the thermal performance of cooling tower to improve or not. However it is hard to control the cooling water temperature that we want under bad air condition or during rainy season. In this paper, the effect of variables, which the ambient air have. especially wet-bulb temperature, are experimentally investigated for controlling the cooling water temperature more successfully. The result is that there is appropriate air flow rate in respective air condition to preserve the cooling performance in the cooling tower and the maximum air flow rate can't overcome the approach under bad air condition.

Heat/Mass Transfer and Flow Characteristics Within a Film Cooling Hole of Square Cross Sections (II) - Effects of Asymmetric Inlet Flow Condition - (정사각 막냉각홀 내부에서의 열/물질전달 및 유동 특성 (II) - 비대칭 입구조건 효과 -)

  • Rhee, Dong-Ho;Kang, Seung-Goo;Cho, Hyung-Hee
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.26 no.7
    • /
    • pp.937-944
    • /
    • 2002
  • An experimental study has been conducted to investigate the heat/mass transfer characteristics within a square film cooling hole with asymmetric inlet now condition. The asymmetric inlet now condition is achieved by making distances between side walls of the secondary now duct and the film cooling hole different; one side wall is $2D_h$ apart from the center of the film cooling hole, while the other side wall is $1.5D_h$ apart from the center of the film cooling hole. The heat/mass transfer experiments for this study have been performed using a naphthalene sublimation method and the now field has been analyzed by numerical calculation using a commercial code. Swirl now is generated at the inlet region and the heat/mass transfer pattem with the asymmetric inlet now condition is changed significantly from that with the symmetric condition. In the exit region, the effect of mainstream on the inside hole now is reduced with the asymmetric condition. The average heat/mass transfer coefficient is higher than that with the symmetric condition due to the swirl now generated by the asymmetric inlet condition.

A Study on the Optimum Cooling Condition of the Underground Power Transmission Cable Equipped with a Separate Pipe Cooling System (간접냉각이 이용된 지중송전케이블의 적정냉각조건에 관한 연구)

  • Park, M.H;Che, G.S.;Seo, J.Y.;Kim, J.G.;Lee, Jae-Heon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.4 no.4
    • /
    • pp.263-276
    • /
    • 1992
  • The transmission current in a power cable is determined under the condition of separate pipe cooling. To this end, the thermal analysis is conducted with the standard condition of separate pipe cooling system, which constitutes one of the underground power transmission system. The changes of transmission current in a power cable with respect to the variation of temperatures and flow rates of inlet cooling water as well as the cooling spans are also determined. As a consequnce, the corresponding transmission current is shown to vary within allowable limit, resulting in the linear variation of the current for most of the cable routes. The abrupt changes of current, however, for the given flow rate of inlet cooling water in some cooling span lead to the adverse effects on the smooth current transmission within the underground power transmission system. In practice, it is expected that the desinging of the separate pipe cooling system in conjunction with the evaluation of system capacity should take into account the effects of design condition on the inlet cooling flow rate.

  • PDF

Heat/Mass Transfer and Flow Characteristics within a Film Cooling Hole of Square Cross Sections with Asymmetric Inlet Flow Condition (비대칭 입구조건을 갖는 정사각 막냉각홀 내부에서의 열/물질전달 및 유동 특성)

  • Rhee, Dong-Ho;Kang, Seung-Goo;Cho, Hyung-Hee
    • Proceedings of the KSME Conference
    • /
    • 2001.11b
    • /
    • pp.14-21
    • /
    • 2001
  • An experimental study has been conducted to investigate the heat/mass transfer characteristics within a square film cooling hole with asymmetric inlet flow conditions. The asymmetric inlet flow condition is achieved by making distances between side walls of secondary flow duct and film cooling hole different; one side wall is $2D_h$ apart from the center of film cooling hole, while the other side wall is $1.5D_h$ apart from the center of film cooling hole. The heat/mass transfer experiments for this study have been performed using a naphthalene sublimation method and the flow field has been analyzed by numerical calculation using a commercial code. Swirl flow is generated at the inlet region and the heat/mass transfer pattern with the asymmetric inlet flow condition is changed significantly from that with the symmetric condition. At the exit region, the effect of mainstream on the inside hole flow is reduced with asymmetric condition. The average heat/mass transfer coefficient is higher than that with the symmetric condition due to the swirl flow generated by the asymmetric inlet condition.

  • PDF

The Study of Deep Level Behaviors in Si Contaminated by Iron (Fe 오염에 따른 Si내의 deep level거동에 관한 연구)

  • Mun, Yeong-Hui;Kim, Jong-O
    • Korean Journal of Materials Research
    • /
    • v.9 no.1
    • /
    • pp.104-107
    • /
    • 1999
  • We investigated the effects of cooling condition on deep levels and iron precipitate formation in iron-contaminated p-type silicon by DLTS(Deep Level Transient Spectroscopy) and preferential etching technique. Dependency of cooling condition on Bulk Micro-Defect (BMD) and four different iron-related deep traps were observed. For normal cooling condition, T1, T2, T3, T4 traps that related to Fe\ulcorner or Fe-O complex were obtained. However, the trap with activation energy, 0.4 eV was observed for slow cooling condition. The trap caused by the $\textrm{Fe}^{+}\textrm{}^{-}$ pair (H4:0.56eV) were detected only at the case of $\textrm{LN}_{2}$ quenching condition.

  • PDF

Internal Flow Condition of High Power Contra-Rotating Small-Sized Axial Fan

  • Shigemitsu, Toru;Fukutomi, Junichiro;Agawa, Takuya
    • International Journal of Fluid Machinery and Systems
    • /
    • v.6 no.1
    • /
    • pp.25-32
    • /
    • 2013
  • Data centers have been built with spread of cloud computing. Further, electric power consumption of it is growing rapidly. High power cooling small-sized fans; high pressure and large flow rate small-sized fan, are used for servers in the data centers and there is a strong demand to increase power of it because of increase of quantity of heat from the servers. Contra-rotating rotors have been adopted for some of high power cooling fans to meet the demand for high power. There is a limitation of space for servers and geometrical restriction for cooling fans because spokes to support fan motors, electrical power cables and so on should be installed in the cooling fans. It is important to clarify complicated internal flow condition and influence of a geometric shape of the cooling fans on performance to achieve high performance of the cooling fans. In the present paper, the performance and the flow condition of the high power contra-rotating small-sized axial fan with a 40mm square casing are shown by experimental and numerical results. Furthermore, influence of the geometrical shape of the small-sized cooling fan on the internal flow condition is clarified and design guideline to improve the performance is discussed.

Thermal Design and Analysis Evaluation of ISG Motor for Hybrid Electric Vehicles considering High-speed Driving Condition (고속 운전조건을 고려한 하이브리드 자동차용 ISG 모터 방열설계 및 해석 평가)

  • Kim, Sung Chul
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.22 no.1
    • /
    • pp.59-64
    • /
    • 2014
  • Integrated Starter Generator (ISG) system improves the fuel economy of hybrid electric vehicles by using idle stop and go function, and regenerative braking system. To obtain the high performance and durability of ISG motor under continuously high load condition, the motor needs to properly design the cooling system (cooling fan and cooling structure). In this study, we suggested the enhanced design by modifying the thermal design of the ISG motor and then analyzed the improvement of the cooling performance under high-speed condition and generating mode by CFD simulation. The temperatures at the coil and the magnet of the enhanced model were decreased by about $4^{\circ}C$ and $6^{\circ}C$, respectively, compared to those of the conventional model. Therefore, we verified the cooling performance enhancement of the novel thermal design in the case of core loss increment due to the higher speed condition.

A Study for Automatic Temperature Control of the Heating-Cooling System with Heat Pump (히트펌프 냉·난방 시스템의 온도 자동제어에 관한 연구)

  • Koo, Chang-Dae
    • Journal of the Korean Society of Industry Convergence
    • /
    • v.14 no.4
    • /
    • pp.143-149
    • /
    • 2011
  • The experiment has been investigated the room temperature change under adjusting 4-way valve which was installed for cooling and heating switch. Beside, the temperature of heat pump was controlled automatically for autonomously adjusting temperature and maintaining a constant room temperature. As results, Inlet & outlet temperature differences of compressor are $95^{\circ}C$ in cooling condition and $57^{\circ}C$ in heating condition. Therefore, Compression efficiency of cooling effect is higher than heating effect. In addition, Heat exchange effect of Cooling system condition is higher than heating system. This results can be used for studying about automatic temperature control of cooling and heating system with heat pump and 4way valve.

Fatigue Life Analysis and Cooling Conditions Evaluation of a Piston for Large LPLi Bus Engines (LPG 액정분사식 대형 버스용 엔진 피스톤의 피로수명 해석과 냉각조건 평가)

  • 최경호;이부윤
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.28 no.5
    • /
    • pp.762-772
    • /
    • 2004
  • Fatigue life of a Piston for large liquid Petroleum liquid injection(LPLi) bus engines is analyzed considering effects of cooling condition parameters : temperature of cooling water, and heat transfer coefficients at oil gallery and bottom surface of piston head. Temperature of the piston is analyzed with varying cooling conditions Stresses of the piston from two load cases of pressure loading. and pressure and thermal loading are analyzed Fatigue life under repeated peak pressure and thermal cycle is analyzed by the strain-life theory. For the two load cases, required loading cycles for engine life are defined, and loading cycles to failure and partial damages are calculated. Based on the resulting accumulated fatigue usage factors, endurance of the piston is evaluated and effects of varying cooling condition Parameters are discussed.

Evaluation of the Lighting Characteristics in High Power White LED Module with Cooling Condition (방열 조건에 따른 5W급 고출력 백색 LED 모듈의 광 특성 평가)

  • Yun, Janghee;Ryeom, Jeongduk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.26 no.12
    • /
    • pp.1-8
    • /
    • 2012
  • The performance and lighting characteristics of the LED depend on cooling condition because the power LED generates lots of heat. In this paper, the effect of the generated heat from power LED module on lighting characteristics and performance is measured and evaluated. For experiments, the transient temperature of a power LED module with cooling condition is measured. In addition, the temperature and lighting characteristics of the LED module are measured during the steady state. As a result, the cooling condition is less effective on the lighting characteristics of the LED module at rated current but the cooling condition extremely affects those of the LED module over the rated current. Because high temperature of the power LED module causes the low phosphor conversion, luminance efficiency becomes low and color temperature becomes high. When power LED module are driven over the rated condition, higher temperature is directly related to lighting characteristics and performance of the LED module rather than higher current.