• Title/Summary/Keyword: Double heat sink

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Fabrication of GaAs Gunn Diodes With A Double Heat Sink (이중 방열 구조를 갖는 GaAs 건 다이오드 제작)

  • Kim, Mi-Ra;Rhee, Jin-Koo;Chae, Yeon-Sik;Lim, Hyun-Jun;Choi, Jae-Hyun;Kim, Wan-Joo
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.46 no.9
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    • pp.1-6
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    • 2009
  • We fabricated Gunn diodes with a double heat sink which has anode heat sink as well as cathode heat sink for efficient heat dissipation. We compared the DC characteristics of a double heat sink diode with a conventional cathode heat sink Gunn diode. It was shown that the Gunn diode with a single heat sink has the threshold voltage of 3 V, the peak current of 744 mA and the breakdown voltage of 4.8 V. Also, the Gunn diode with a double heat sink showed the threshold voltage of 2.5 V, the peak current of 778 mA and the breakdown voltage over 5 V.

INFLUENCE OF CONSTANT HEAT SOURCE/SINK ON NON-DARCIAN-BENARD DOUBLE DIFFUSIVE MARANGONI CONVECTION IN A COMPOSITE LAYER SYSTEM

  • MANJUNATHA, N.;SUMITHRA, R.;VANISHREE, R.K.
    • Journal of applied mathematics & informatics
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    • v.40 no.1_2
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    • pp.99-115
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    • 2022
  • The problem of Benard double diffusive Marangoni convection is investigated in a horizontally infinite composite layer system consisting of a two component fluid layer above a porous layer saturated with the same fluid, using Darcy-Brinkman model with constant heat sources/sink in both the layers. The lower boundary of the porous region is rigid and upper boundary of the fluid region is free with Marangoni effects. The system of ordinary differential equations obtained after normal mode analysis is solved in closed form for the eigenvalue, thermal Marangoni number for two types of thermal boundary combinations, Type (I) Adiabatic-Adiabatic and Type (II) Adiabatic -Isothermal. The corresponding two thermal Marangoni numbers are obtained and the essence of the different parameters on non-Darcy-Benard double diffusive Marangoni convection are investigated in detail.

A Study on Performance of Vertical Ground Heat Exchanger for Heat Pump (히트펌프용 수직형 지중열교환기의 성능에 관한 연구)

  • Chang, Ki-Chang;Chung, Min-Ho;Yoon, Hyung-Kee;Ra, Ho-Sang;Yoo, Seong-Yeon
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.06a
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    • pp.466-469
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    • 2007
  • Heat pumps are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating mode and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal type and vertical type according to the installation method. A horizontal type means that a heat exchanger is laid in the trench bored in 1.2 to 1.8 m depth. And a vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double n-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

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A Study on Heat Transfer Performance of Vertical Ground Heat Exchanger of GSHP(Ground Source Heat Pump) (GSHP용 수직형 지중열교환기의 열전달 성능에 관한 연구)

  • Chung, Min-Ho;Chang, Ki-Chang;Ra, Ho-Sang;Baik, Young-Jin;Park, Seong-Ryong;Yoo, Seong-Yeon
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2102-2107
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    • 2007
  • GSHP systems are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal and vertical type according to the installation method. Vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double u-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

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