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<p>This study examines the challenges associated with freezing conditions in air-source heat pump systems (ASHP), with a focus on defrost methods and the experimental evaluation of a poppet-type solenoid valve (PTV) as an alternative to the traditional four-way valve (FWV). In case of the outdoor temperature falls below the dew point, frost formation is possible on ASHP evaporators depending on various operational and environmental factors. This experimental study compared the performance of a heat pump system using a poppet valve to one with a four-way valve, emphasizing defrost duration and its impact on system efficiency. Both systems operated in cooling mode for 10&#xa0;min, followed by a one-minute defrost cycle, repeated over 10 cycles. Results showed the poppet valve system achieved a coefficient of performance (COP) of 6.07, outperforming the four-way valve system’s COP of 5.42 by 11.99%. Additionally, heat released to the indoor environment during defrost was 24.5% lower in the poppet valve system. Maximum indoor temperature increases during defrost were 8&#xa0;°C and 4.8&#xa0;°C for the four-way and poppet valve systems, respectively. Exergy analysis revealed the poppet valve system experienced 10.09% less exergy loss and demonstrated 49.99% higher exergy efficiency. Uncertainty analysis of the system was performed, and it was found to be at an acceptable level. These results suggest the poppet-type solenoid valve is a viable alternative for enhancing energy efficiency and stability in heat pump systems, with potential for broader application in industrial settings such as VRV-F systems.</p>

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Comprehensive experimental study on the energy and exergy analysis of the defrost components of an air-source heat pump

  • 期刊论文

  • 发表日期：

    2025年12月25日

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  • Khaled A. A. Babay,
  • Dilara Tezcan,
  • Abdullah Dağdeviren,
  • Şafak Ataş

摘要

This study examines the challenges associated with freezing conditions in air-source heat pump systems (ASHP), with a focus on defrost methods and the experimental evaluation of a poppet-type solenoid valve (PTV) as an alternative to the traditional four-way valve (FWV). In case of the outdoor temperature falls below the dew point, frost formation is possible on ASHP evaporators depending on various operational and environmental factors. This experimental study compared the performance of a heat pump system using a poppet valve to one with a four-way valve, emphasizing defrost duration and its impact on system efficiency. Both systems operated in cooling mode for 10 min, followed by a one-minute defrost cycle, repeated over 10 cycles. Results showed the poppet valve system achieved a coefficient of performance (COP) of 6.07, outperforming the four-way valve system’s COP of 5.42 by 11.99%. Additionally, heat released to the indoor environment during defrost was 24.5% lower in the poppet valve system. Maximum indoor temperature increases during defrost were 8 °C and 4.8 °C for the four-way and poppet valve systems, respectively. Exergy analysis revealed the poppet valve system experienced 10.09% less exergy loss and demonstrated 49.99% higher exergy efficiency. Uncertainty analysis of the system was performed, and it was found to be at an acceptable level. These results suggest the poppet-type solenoid valve is a viable alternative for enhancing energy efficiency and stability in heat pump systems, with potential for broader application in industrial settings such as VRV-F systems.