Experimental investigation on predictive models for motive flow calculation through ejectors for transcritical CO

G. Boccardi, G. Lillo, R. Mastrullo, A.W. Mauro, L. Saraceno, M. Pieve, R. Trinchieri

Research output: Contribution to conferencePaper

Abstract

Nowadays, air conditioning systems, especially those used in residential and office buildings, contribute largely to the energy consumptions and to the direct and indirect emissions of greenhouse gases. Carbon dioxide (CO2) is an interesting option to replace traditional HFCs in vapor compression systems, due to its environmentally friendly characteristics: zero ODP and extremely low GWP. In the case of heat pumps, the use of ejection systems for the expansion phase can contribute to recovery a fraction of the mechanical energy otherwise dissipated as friction, bringing to significant benefits in terms of performance. Currently, at the laboratory DTE-PCU-SPCT of the research center ENEA (Casaccia) in cooperation with the Industrial Engineering Department of Federico II University of Naples, a project is in progress, in order to evaluate experimentally the effect of several ejectors geometries on the global performance of a CO2heat pump working with a transcritical cycle. As a part of this project, measurements of the motive flow mass flow rate have been carried out, in transcritical CO2conditions. The ejector sizing is a crucial point for the balancing of components and the correct operation of the CO2heat pump and therefore the availability of reliable calculation methods for the motive flowrate would be useful. This paper presents the results obtained by a comparison between the new experimental data and the predictions of some predictive semi-empirical correlations available in the open literature for transcritical CO2conditions. Their predictions are analyzed as a function of the main physical parameters of the process to assess their reliability compared to the experimental data. Based on these indications and of the available experimental data, a new semi-empirical correlations and a calculation method based on the hypothesis of isentropic and choked two-phase flow are presented.
Original languageEnglish
DOIs
Publication statusPublished - 20 Nov 2017
Event35th Italian Union of Thermo-Fluid Dynamics Heat Transfer Conference, UIT 2017 - Ancona, Italy
Duration: 20 Nov 2017 → …

Conference

Conference35th Italian Union of Thermo-Fluid Dynamics Heat Transfer Conference, UIT 2017
CountryItaly
CityAncona
Period20/11/17 → …

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Boccardi, G., Lillo, G., Mastrullo, R., Mauro, A. W., Saraceno, L., Pieve, M., & Trinchieri, R. (2017). Experimental investigation on predictive models for motive flow calculation through ejectors for transcritical CO. Paper presented at 35th Italian Union of Thermo-Fluid Dynamics Heat Transfer Conference, UIT 2017, Ancona, Italy. https://doi.org/10.1088/1742-6596/923/1/012018