• Title/Summary/Keyword: Cold exit mass fraction

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A PARAMETRIC STUDY OF CONICAL FRUSTUM GEOMETRY FOR IMPROVEMENT OF COOLING PERFORMANCE OF VORTEX TUBE (Vortex Tube 성능 개선을 위한 절두체의 형상 매개변수에 대한 연구)

  • Koo, H.B.;Park, J.Y.;Sohn, D.Y.;Choi, Y.H.
    • Journal of computational fluids engineering
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    • v.20 no.4
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    • pp.7-13
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    • 2015
  • Vortex tube is a thermal static device that separates compressed air into hot and cold streams. In general, the cooling efficiency of vortex tubes is lower than that of traditional air conditioning equipment and vortex tubes are mainly used for industrial spot cooling applications because of their quick responses. In this study, conical frustums are employed in the nozzle chamber to improve the cooling performance. Conical frustums can be used to decrease the ineffective mass fraction that directly passes through the cold exit without energy separation. The shape optimization of conical frustums has been performed using full factorial design. It is found that the height of frustums has the largest main effects on the cooling performance. Computational results show that the cooling performance can be increased by about 10% within the considered range of the design parameters. This is because the ineffective mass fraction toward the cold exit is decreased by about 20%.

Experimental Investigation for the Characteristics of Energy Separation of a Vortex Tube at Various Inlet and outlet Pressure Conditions (입.출구의 압력조건에 따른 보텍스 튜브의 에너지분리 특성에 관한 실험적 고찰)

  • 유갑종;김정수;최인수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.11
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    • pp.1149-1155
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    • 2001
  • The experimental investigation on energy separation in a vortex tube has been carried out to sow the effect of inlet and outlet pressures with various working fluids(air,$O_2,\;and\; CO_2$). Those outlet pressure means cold outlet and hot outlet pressure which were set equally. The results showed that the total enthalpy variation became a maximum when the mass flow rate at the cold outlet was a half of the total mass flow rate in the vortex tube (y=0.5). The total enthalpy variation was quite affected by the pressure difference between the inlet and outlet of vortex tube when the ratio of the inlet pressure to the cold outlet pressure remained constant. Although specific enthalpy differences between the inlet and the outlet (both cold and hot outlet) did not noticeably vary with the pressure difference, the specific enthalpy difference between the inlet and cold outlet was dominantly affected by physical properties of working gases.

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A Numerical Study of the 2-D Cold Flow for a Qubec City Stoker Incinerator (큐벡시 스토커 소각로 2차원 비반응 유동장 수치해석)

  • 박지영;송은영;장동순
    • Journal of Energy Engineering
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    • v.2 no.3
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    • pp.268-275
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    • 1993
  • A series of parametric investigations are performed in order to resolve the flow characteristic of a Quebec city stoker incinerator. The parameters considered in this study are five internal configurations of the Quebec city stoker itself and its modified ones, primary air velocity, the injection velocity and angle of the secondary air, and the reduction of the stoker exit area. A control-volume based finite-difference method by Patankar together with the power-law scheme is employed for discretization. The resolution of the pressure-velocity coupling is made by the use of SIMPLEC algorithm. The standard, two equation, k-$\varepsilon$ model is incorporated for the closure of turbulence. The size of recirculation region, turbulent viscosity, the mass fraction of the secondary air and pressure drop are calculated in order to analyze the characteristics of flow field. The results are physically acceptable and discussed in detail. The flow field of the Quebec city stoker shows the strong recirculation zone together with the high turbulence intensity over the upper part of the incinerator.

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