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Review of electronic expansion valve correlations for heat pump and air conditioning systems.

Number: pap. 2480

Author(s) : WANG H., HWANG Y., RADERMACHER R., et al.

Summary

Split-type air-conditioning systems with multiple indoor units and variable capacity feature, also known as variable refrigerant flow systems (VRF), are growing in both residential and commercial buildings for its flexibility in configurations and high energy efficiency through zoning control and variable capacity control. The VRF system controls its capacity by the combination of drive frequency of variable speed compressor and opening of electronic expansion valves (EEV). According to fluid dynamics analysis, the mass flow rate is a function of the EEV opening. Therefore, the accurate correlation of mass flow rate through an EEV is important in accurate prediction of the mass flow rate in the VRF systems and design the control system. The simulation and experiment studies are reviewed in this paper. Literature study shows that the most commonly used approach is power-law correlation which is recommended by ASHRAE. The relative deviation of the predicted mass flow of this method is around 5% to 40% depending on the refrigerants used. Different refrigerants including R22, R245a, R134a, R410A, R407C and R744 have been studied since 2005. Second type is polynomial fit correlation developed in 2013, which is a simplified model and has a relative deviation of 5% for 98% of the data. Third type is using Artificial Neural Network (ANN) algorithm, which has a relative deviation from 1% to 4% and has been used since 2015. In addition, a dynamic model of EEV has been developed since 2016. In conclusion, power-law correlation is the most popular method with a relatively high precision. Polynomial fit correlation is convenient to use but has a lower precision. ANN curve fitting which has a very high precision is a novel approach to be utilized in EEV correlation. However, only a few researches concentrate on this method. Therefore, more research about ANN is needed.

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Pages: 8

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Details

  • Original title: Review of electronic expansion valve correlations for heat pump and air conditioning systems.
  • Record ID : 30024575
  • Languages: English
  • Source: 2018 Purdue Conferences. 17th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2018/07/09

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