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Insights gained from the experimental testing of air source heat pump under frosting conditions.

Number: 2455

Author(s) : HAMID I., TAUSEEF I., SIDDHARTH R., JULFIKAR A., ALEXANDER A., BACH C. K.

Summary

This paper presents the lessons learned from a series of frosting and defrosting experiments using a residential air source heat pump (ASHP). In this paper, we focus on the role of psychrometric chamber control and its interaction with equipment during the defrosting cycle.
The transient nature of heat pump operation causes instabilities during defrosting. We explain the importance of careful control over the environment and the system to achieve reliable and repeatable results. We found that the initial condition of the ASHP coil – dry vs. wet – at the start of the first frosting process changes the unit’s behavior. Starting experiments with a dry coil is a first step towards repeatable behavior. During ASHP operation, stability of temperature and humidity is required. Fluctuations in humidity due to controls or other issues cause non-repeatable behavior and can be caused by the humidifier controls or the ASHP unit’s defrosting cycle. Controlling the psychrometric chambers’ temperature and humidity during frosting and defrosting cycle ensure the reliability and accuracy of the experiments.
The heat pump is operated in parallel with the psychrometric chamber to rapidly achieve the desire target temperature, which degrades the performance of ASHP. This approach decreases the frosting time due to pre-condensation occurring until stable conditions are reached, which should be avoided to maintain realistic performance. Therefore, the heat pump should only be operated after the target conditions are reached in the outdoor psychrometric chamber.

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Pages: 8 p.

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  • Original title: Insights gained from the experimental testing of air source heat pump under frosting conditions.
  • Record ID : 30033114
  • 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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