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Optimal refrigerant flow configurations in a fin-tube heat exchanger for an indoor unit of a heat pump using R466A

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Abstract

This study investigates the optimal refrigerant flow path for a fin-tube heat exchanger used in the indoor unit of a mini VRF heat pump. Optimal circuitry can significantly enhance the performance of fin-tube heat exchangers. Its performance according to various refrigerant circuitry is evaluated by the developed finite-element-calculation simulation model. The refrigerant circuitry was optimized by maximizing the heat transfer rate for given refrigerant and air conditions during cooling and heating seasons by adopting an optimization algorithm. A four-circuit circuitry has a higher capacity than the six-circuit circuitry and two-circuit circuitry because of the balancing effect of pressure drop and heat transfer. The best circuitry, which contains split/merge tubes, has a higher capacity and a significant pressure drop reduction compared to the two-circuit circuitry. It is found that compared to the reference circuitry, the best circuitry for the indoor unit of the heat pump has a 13 % increase in capacity.

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Abbreviations

A :

Element heat transfer area (m2)

b r :

Enthalpy-temperature ratio between the mean tube and water temperature (J/kg·K)

b t :

Enthalpy-temperature ratio between outside and inside tube wall temperature (J/kg·K)

b wm :

Enthalpy-temperature ratio at the mean water film temperature of the airside surface (J/kg·K)

C :

Heat capacity rate (W/K)

C r :

Capacity rate ratio

D :

Depth of heat exchanger (mm)

GWP :

Global warming potential

H :

Height of heat exchanger (mm)

h :

Heat transfer coefficient (W/m2·K)

HTC :

Heat transfer coefficient (W/m2·K)

k :

Thermal conductivity of tube material (W/m·K)

NTU :

Number of transfer units

Q :

Heat capacity (W)

T :

Temperature (°C or K)

t :

Tube thickness (m)

U :

Overall heat transfer coefficient (W/m2·K)

VRF :

Variable refrigerant flow

W :

Width of heat exchanger (mm)

X :

Refrigerant circuitry variable

Δ:

Difference

ε :

Effectiveness of heat exchanger

η o :

Overall surface efficiency

COND :

Condenser

ele :

Element

EVAP :

Evaporator

i :

Refrigerant side, index of circuitry

M :

Number of parent circuitries

min :

Minimum

N :

Number of circuitries in the population

o :

Air side

ow :

Wet surface

t :

Tube outer surface

THC :

Total heat capacity

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Acknowledgments

This work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program-Development of Automotive Industry Technology) (20018706, Development of 500 W indoor mounted low-noise compact heat pump system technology for improving xEV local air conditioning performance and efficiency) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea).

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Authors and Affiliations

  1. Department of Mechanical Engineering, Graduate School, Kookmin University, Seoul, 02707, Korea

    Amal Vasu & Yeon Sung Yoo

  2. School of Mechanical Engineering, Kookmin University, Seoul, 02707, Korea

    Young Soo Chang

Authors
  1. Amal Vasu
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  2. Yeon Sung Yoo
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  3. Young Soo Chang
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Corresponding author

Correspondence to Young Soo Chang.

Additional information

Amal Vasu received the M.Tech. degree from University of Kerala, Kerala, India in 2016. Currently, he is a doctoral student at the Department of Mechanical Engineering, Kookmin University, Seoul, Korea. His research interests include refrigeration and air-conditioning, heat transfer and two-phase flow.

Yeon Sung Yoo is currently a Master’s student in the Department of Mechanical Engineering, Kookmin University, Seoul, Korea. His current research interests focus on heat transfer in refrigeration and air-conditioning.

Young Soo Chang received the Ph.D. degree from Seoul National University, Seoul, Korea in 1997. Currently, he is a Professor at the School of Mechanical Engineering, Kookmin University, Seoul, Korea. His research interests include heat transfer and smart control of HVAC systems.

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Vasu, A., Yoo, Y.S. & Chang, Y.S. Optimal refrigerant flow configurations in a fin-tube heat exchanger for an indoor unit of a heat pump using R466A. J Mech Sci Technol 38, 997–1006 (2024). https://doi.org/10.1007/s12206-024-0147-4

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  • DOI: https://doi.org/10.1007/s12206-024-0147-4

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