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Evaluation of flow, heat transfer, and phase change characteristics in microchannel condensers using computational fluid dynamic (CFD) simulations.

Number: 2195

Author(s) : ASZTALOS K. J., AMEEN M., WAIKAR A., ROWINSKI D.

Summary

Heat pumps provide an efficient path towards decarbonizing HVAC systems. There is a strong need to develop heat pumps (HP) that can operate with low-GWP refrigerants, have a low-power requirement and are compact, and can be efficient under challenging conditions. Microchannel condensers can be utilized for heat transfer and cooling for extremely high heat flux, and have applications in HVAC, heat pumps, and micro-refrigeration systems. Replacing the condenser in the heat pumps with microchannel condensers is a potential pathway to make the heat pumps more compact. For these devices, the flow patterns that determine the condensation heat transfer rate differ from conventional macro-channels, which presents unique modeling challenges. Opportunities exist to utilize high-fidelity computational fluid dynamical (CFD) simulations to accurately capture and model the flow pattern development for refrigerants key to global decarbonization goals, such as low-GWP refrigerants, and for operation in extreme weather conditions (i.e. extreme cold). The larger scope of this work aims to close the gap on the modeling front by incorporating device simulations including all the key physics leading to more predictive simulations. This study is focused on the technical aspects of microchannel condensers found in heat pumps, and in particular, the use of high-fidelity computational fluid dynamics (CFD) to accurately capture and model flow pattern development for a range of operating conditions. CFD simulations utilizing volume-of-fluid (VOF) modeling of a simplified parallel square microchannel geometry were performed, and validation with experimental measurements was completed for the refrigerant Fluorinert FC-72. Good agreement is observed with experiments in capturing the liquid mass fraction as measured at the outlet for a range of operating conditions corresponding to varying the mass flowrate at the inlet and the spatial heat flux on the
sides of the condenser. The validated CFD setup will be utilized in the continuation of this work to investigate the effect of microchannel geometry and refrigerant property on the flowfield development and condensation. Preliminary simulations investigating the effect of geometry and refrigerant properties were performed.

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  • Original title: Evaluation of flow, heat transfer, and phase change characteristics in microchannel condensers using computational fluid dynamic (CFD) simulations.
  • Record ID : 30033074
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 20th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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