• 대한기계학회논문집B
• /
• 제25권12호
• /
• pp.1784-1792
• /
• 2001

Numerical analysis on a parallel flow heat exchanger(PFHE) is performed using 2 dimensional turbulent porous modeling. This modeling can consider three-dimensional configuration of passage (flat tube with micro-channels), and the stability and accuracy of numerical results are improved. The geometrical parameters(e.g., the position of separators, inlet/outlet, and porosity of passages of a PFHE) are varied in order to examine the flow and thermal characteristics and flow distribution of the single phase multiple passages system. The flow non-uniformities along the paths of the PFHE are observed to evaluate the thermal performance of the heat exchanger. The location of inlet affects the heat transfer, and the location of outlet affects the pressure drop. The porosity with the optimum thermal performance is around 0.53.

• 대한기계학회논문집B
• /
• 제22권2호
• /
• pp.229-239
• /
• 1998

The present paper examines the thermal and flow characteristics of a parallel flow heat exchanger and investigates the effects of the parameters on thermal performance by defining the flow nonuniformity. Thermal performance of a parallel flow heat exchanger is maximized by the optimization using Newton's searching method. The flow nonuniformity is chosen as an object function. The parameters such as the locations of separator, inlet, and outlet are expected to have a large influence on thermal performance of a parallel flow heat exchanger. The effect of these parameters are quantified by flow nonuniformity. The results show that the optimal locations of inlet and outlet are 19.73 mm and 10.9 mm, respectively. It is also shown that the heat transfer increases by 7.6% and the pressure drop decreases by 4.7%, compared to the reference model.

• 설비공학논문집
• /
• 제12권9호
• /
• pp.802-809
• /
• 2000

This study numerically analyzes the thermal and flow characteristics inside the header in PFHE(parallel-flow heat exchanger) by employing a three-dimensional turbulence modeling. The following quantities are examined by varying the injection angle of the working fluid, the location of entrance and the shape of entrance: flow nonuniformity, heat transfer rate, and flow distribution in each passage. The result shows that the degree of significance among the parameters affecting the header part is in the order of the injection angle, the shape of entrance, and the location of entrance. The result also indicates that heat transfer rates compared to the reference model are increased by about 152% for the angle of injection of -$20^{\circ}C$, by about 127% for the shape of entrance with right and left long rectangular form, and by about 108% for the location of entrance located at the lowest Position.

• 설비공학논문집
• /
• 제13권10호
• /
• pp.1017-1024
• /
• 2001

The optimum shape of header part in a PFHE (parallel-flow heat exchanger) is studied. The optimal values of each geometric parameter are proposed according to their order of influence with varying the four important parameters (the injection angle of working fluid ($\Theta$), the shape of inlet(S), the location of inlet ($y_c/D_{in}$) and the height of the protruding flat tube ( $y_{b/}$ $D_{in}$ )). The optimal geometric parameters are as follows:$\Theta= -21^{\circ}C,\; S=Type\; A \;an\;y_b/D_{in}$/=0. The heat transfer rate of the optimum model, compared to that of the reference model, is increased by about 55%. The optimal geometric parameters ran be applicable to the Reynolds number ranging from 5,000 to 20,000.0.