Research Papers: Multiphase Flows

Numerical Approach to Study Nonuniform Gas–Liquid Distribution in the Refrigerant Distributor in an Air Conditioner

[+] Author and Article Information
Eiji Ishii

Research and Development Group,
Hitachi, Ltd.,
832-2, Horiguchi,
Ibaraki 312-0034, Japan
e-mail: eiji.ishii.qm@hitachi.com

Masanori Ishikawa

Research and Development Group,
Hitachi, Ltd.,
832-2, Horiguchi,
Ibaraki 312-0034, Japan
e-mail: masanori.ishikawa.sf@hitachi.com

Kazuki Yoshimura

Research and Development Group,
Hitachi, Ltd.,
832-2, Horiguchi,
Ibaraki 312-0034, Japan
e-mail: kazuki.yoshimura.ox@hitachi.com

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received January 30, 2015; final manuscript received May 18, 2015; published online July 7, 2015. Assoc. Editor: Kwang-Yong Kim.

J. Fluids Eng 137(11), 111303 (Nov 01, 2015) (7 pages) Paper No: FE-15-1069; doi: 10.1115/1.4030679 History: Received January 30, 2015; Revised May 18, 2015; Online July 07, 2015

Factors that influence the nonuniform gas–liquid distribution in refrigerant distributors in air conditioners were studied. Gas–liquid flows in two-pass and multipass distributors were numerically simulated with a particle/grid hybrid method; droplets and liquid films were mainly simulated using a particle method, and gas flows were simulated using a grid method. Complex behaviors of multiscale gas–liquid interfaces in the multipass distributor were simulated because droplets that were smaller than the grid size could be simulated without numerical diffusion through the gas–liquid interfaces. The effect of the connecting angle of the bend pipe was studied in the two-pass distributor, whereas the effect of the tube's position relative to the distributor inflow and the effect of gravity were investigated in the multipass distributor. The model was validated against multiple experimental data taken from an at-scale physical model. We found that the direction of gravity plays a role in ensuring a uniform distribution of liquid in the multipass distributor for ensuring a uniform distribution.

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Fig. 2

Simulation procedure of hybrid method

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Fig. 1

Schematic view of air conditioner indoor unit

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Fig. 3

Computational models of two-pass distributors: (a) view of distributor connected to a bend pipe at connecting angle of 30 deg, (b) bottom views showing connecting angles θ of 30 deg, (c) 60 deg, and (d) 90 deg

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Fig. 4

Simulated liquid distribution at connecting angle of 30 deg: (a) front and (b) bottom view around connecting region between bend pipe and distributor

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Fig. 5

Distribution ratio of liquid on right pass to that on left pass for connecting angle of 30 deg. The simulation results are the distribution ratio over time. The measurement was made under steady flow conditions.

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Fig. 9

(a) Computational model of multipass distributor and (b) close-up of bottom of distributor

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Fig. 10

Simulated liquid distribution in multipass distributor

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Fig. 11

Measured temperature distribution on surface of multipass heat exchanger. The temperature is a nondimensional temperature T/ΔT, where T is the temperature, and ΔT is the difference between the maximum and minimum temperatures.

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Fig. 12

Dependence of liquid distributions in multipass distributors on direction of gravity; gravity directions: (a) +Y and (b) +Z

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Fig. 13

Liquid distributions in half section at bottom of distributor for different gravity directions: (a) −Y direction (original direction shown in Fig. 10), (b) +Y direction, and (c) +Z direction

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Fig. 6

Grid-dependence study. The number of computational mesh cells was changed to 308,796, 371,280, and 462,400.

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Fig. 7

Grid-dependence study. Simulated liquid distribution with (a) 308,796 mesh cells and (b) 371,280 mesh cells.

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Fig. 8

Dependence of distribution ratio on connecting angle between bend pipe and distributor. The initial particle distance of s was 0.357 or 0.278 in MPS.



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