Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit

During winter heating operations, the cold air discharged by air source heat pump (ASHP) units accumulates around them, resulting in a cold island effect that decreases the system's heating capacity. This paper presents an unsteady computational fluid dynamics (CFD) simulation model to investig...

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Main Authors: Jiashuo Zhou, Ronghua Wu, Hao Yu, Jiyou Lin, Hao Zhan, Shunjie Liu, Zhibin Wang
Format: Article
Language:English
Published: Elsevier 2025-10-01
Series:Case Studies in Thermal Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S2214157X25010172
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author Jiashuo Zhou
Ronghua Wu
Hao Yu
Jiyou Lin
Hao Zhan
Shunjie Liu
Zhibin Wang
author_facet Jiashuo Zhou
Ronghua Wu
Hao Yu
Jiyou Lin
Hao Zhan
Shunjie Liu
Zhibin Wang
author_sort Jiashuo Zhou
collection DOAJ
description During winter heating operations, the cold air discharged by air source heat pump (ASHP) units accumulates around them, resulting in a cold island effect that decreases the system's heating capacity. This paper presents an unsteady computational fluid dynamics (CFD) simulation model to investigate the airflow organization of a single ASHP unit. It examines how environmental temperature, wind speed, and air volume influence airflow patterns and analyzes the effects on the coefficient of performance (COP). The findings reveal a maximum relative error of 14.5 % between the simulated and experimental COP results. The airflow organization progresses through three stages: viscosity-dominated, accelerated suction, and periodic ejection. The cold island effect can lead to a 3.28 % drop in baseline COP compared to the theoretical COP, with decreases reaching 4.17 % at an ambient temperature of 15 °C and 6.54 % at an air volume of 13527 m3/h. The research findings of this study provide a basis for the quantitative engineering analysis of performance degradation in single-unit air-source heat pump systems caused by the cold island effect. Additionally, the introduction of a non-steady-state model offers new insights into the precise characterization of the cold island effect in air-source heat pump units.
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series Case Studies in Thermal Engineering
spelling doaj-art-a33d3c788c484a4597f7b15d4ae722732025-08-01T04:44:38ZengElsevierCase Studies in Thermal Engineering2214-157X2025-10-0174106757Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unitJiashuo Zhou0Ronghua Wu1Hao Yu2Jiyou Lin3Hao Zhan4Shunjie Liu5Zhibin Wang6School of New Energy, Harbin Institute of Technology at Weihai, Weihai, 264209, ChinaSchool of New Energy, Harbin Institute of Technology at Weihai, Weihai, 264209, China; Corresponding author.School of New Energy, Harbin Institute of Technology at Weihai, Weihai, 264209, ChinaSchool of New Energy, Harbin Institute of Technology at Weihai, Weihai, 264209, ChinaSchool of New Energy, Harbin Institute of Technology at Weihai, Weihai, 264209, ChinaQingdao Gaoxin Gaoke Clean Energy Co., Ltd., Qingdao, 266209, ChinaQingdao Gaoxin Gaoke Clean Energy Co., Ltd., Qingdao, 266209, ChinaDuring winter heating operations, the cold air discharged by air source heat pump (ASHP) units accumulates around them, resulting in a cold island effect that decreases the system's heating capacity. This paper presents an unsteady computational fluid dynamics (CFD) simulation model to investigate the airflow organization of a single ASHP unit. It examines how environmental temperature, wind speed, and air volume influence airflow patterns and analyzes the effects on the coefficient of performance (COP). The findings reveal a maximum relative error of 14.5 % between the simulated and experimental COP results. The airflow organization progresses through three stages: viscosity-dominated, accelerated suction, and periodic ejection. The cold island effect can lead to a 3.28 % drop in baseline COP compared to the theoretical COP, with decreases reaching 4.17 % at an ambient temperature of 15 °C and 6.54 % at an air volume of 13527 m3/h. The research findings of this study provide a basis for the quantitative engineering analysis of performance degradation in single-unit air-source heat pump systems caused by the cold island effect. Additionally, the introduction of a non-steady-state model offers new insights into the precise characterization of the cold island effect in air-source heat pump units.http://www.sciencedirect.com/science/article/pii/S2214157X25010172Air source heat pumpCold island effectCoefficient of performance (COP)Numerical simulationUnsteady state
spellingShingle Jiashuo Zhou
Ronghua Wu
Hao Yu
Jiyou Lin
Hao Zhan
Shunjie Liu
Zhibin Wang
Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit
Case Studies in Thermal Engineering
Air source heat pump
Cold island effect
Coefficient of performance (COP)
Numerical simulation
Unsteady state
title Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit
title_full Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit
title_fullStr Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit
title_full_unstemmed Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit
title_short Numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit
title_sort numerical simulation of unsteady airflow organization and cold island effect in air source heat pump unit
topic Air source heat pump
Cold island effect
Coefficient of performance (COP)
Numerical simulation
Unsteady state
url http://www.sciencedirect.com/science/article/pii/S2214157X25010172
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