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Modeling the effect of non-uniform frost accumulation on the performance of heat pump with refrigerant side flow maldistribution.

Number: 2361

Author(s) : ISMAIL T., IKRAM H., ALEXANDER A., BACH C. K.

Summary

During winter operations, the effectiveness of air source heat pump (ASHP) systems can be substantially compromised by the buildup of frost on evaporator coil surfaces. A numerical model for frost growth has been developed that predicts frost accumulation on the outdoor coil of the ASHP and the performance degradation caused by the frost aggregation. The moving boundary technique is used on the refrigerant side of the heat exchanger while on the air side epsilon-NTU is used for quasi steady state heat transfer from the air to the refrigerant. The air side pressure drop increases as frost grows on the fins. The air flowrate is adjusted by a fan model for each time step as the frost thickness increases. The evaporator model can predict non-uniform frost formation, includes air- and refrigerant-flow maldistribution, and predicts superheat using a moving boundary approach. The system model predicts a reduction in the total capacity as the frost thickness increases. This decrease in overall capacity is due to the drop in both suction and discharge temperatures, and the air mass flowrate across the coil, leading to a reduction in the system's coefficient of performance. The model predictions are within ±5% of experimental results.

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  • Original title: Modeling the effect of non-uniform frost accumulation on the performance of heat pump with refrigerant side flow maldistribution.
  • Record ID : 30033161
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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