HEM and HRM accuracy comparison for the simulation of CO2 expansion in two-phase ejectors for supermarket refrigeration systems

By M. Palacz, M. Haida, Jacek Smolka, Andrzej J. Nowak, K. Banasiak, Armin Hafner. 2017

82 citations recorded by the source corpus.

In this study, the accuracies of the homogeneous equilibrium (HEM) and homogeneous relaxation models (HRM) were compared. Both models were implemented in the ejectorPL computational tool. The HEM and HRM were used to simulate the carbon dioxide flow in ejectors that were designed for supermarket refrigeration systems. The model accuracy was evaluated by comparing the computational results with the experimental data. The discrepancy between the measured and computed motive nozzle mass flow rates was analysed. In addition, the difference between the experimental and computational mass entrainment ratios was calculated. The operating regimes in this study ranged from 47 bar to 94 bar and from 6 °C to 36 °C for the pressure and temperature, respectively. The model accuracy strongly depends on the distance between the operating regime and the critical point of the refrigerant. The discrepancy for the selected operating regimes ranged from 0.3% to 43.3% and 0.7% to 42.0% for HEM and HRM, respectively. For lower pressures and temperatures, the HRM has higher accuracy than the HEM. The errors of the HRM results were approx. 5% lower than those of the HEM results. The accuracy improvement of the HRM was considered unsatisfactory. The low accuracy improvements were possibly caused by the relaxation time formulation in the homogeneous relaxation model.

Subfields: Biomedical Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/3188bcbe4f6410c2094443236becc11d6c04037f

How researchers see this paper

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In Biomedical Engineering

1. Armin Hafner
2. K. Banasiak

In Mechanical Engineering

1. Andrzej J. Nowak
2. Jacek Smolka
3. M. Haida
4. M. Palacz
5. Armin Hafner
6. K. Banasiak

Citations in the corpus

• Modified homogeneous relaxation model for the r744 trans-critical flow in a two-phase ejector (2018, methodology): “Palacz et al. (2017b) used genetic and evolutionary algorithms to optimise the ejector shape of the R744 two-phase ejector based on the HEM at the operating conditions typical for supermarket application.”