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Methods for tuning the mass flow rate of unitary equipment models.

Author(s) : SHEN B., GROLL E. A., BRAUN J. E.

Summary

The paper discusses several parameters that may cause inaccurate mass flow rate calculations in unitary air conditioner and heat pump simulation models. Two tuning methods to achieve a higher accuracy in refrigerant mass flow rate predictions are introduced. Typically, a detailed description of the inlet parameters of a short-tube orifice is often not available. However, the inlet parameters have a significant effect on the flow characteristics through the orifice. The paper presents a method of tuning an entrance geometrical constant that is associated with the orifice inlet. This tuning method requires measurements at one operating condition. The tuning method performs well at normal operating conditions, and it can be used to identify when two-phase flow enters the orifice, in which case special modelling needs to be considered. The effect of ambient temperature on compressor mass flow rate is generally not considered in simulation models. The paper presents a second tuning method to correct for the effect of ambient temperature that requires system capacity measurements at two ambient temperatures. The ability of the models to predict system performance both before and after tuning is evaluated over a wide range of operating conditions for two unitary units tested within the laboratory.

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Details

  • Original title: Methods for tuning the mass flow rate of unitary equipment models.
  • Record ID : 2005-2752
  • Languages: English
  • Source: 21st IIR International Congress of Refrigeration: Serving the Needs of Mankind.
  • Publication date: 2003/08/17

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