Blar i NTNU Open på forfatter "Nowak, Andrzej J."
-
A modified homogeneous relaxation model for CO2 two-phase flow in vapour ejector
Haida, Michal; Palacz, Michal; Smolka, Jacek; Nowak, Andrzej J.; Hafner, Armin; Banasiak, Krzysztof (Journal article; Peer reviewed, 2016)In this study, the homogenous relaxation model (HRM) for CO2 flow in a two-phase ejector was modified in order to increase the accuracy of the numerical simulations The two- phase flow model was implemented on the effective ... -
Analysis of supermarket CO2 refrigeration cycles equipped with multi-ejectors
Wiecha, Jakub Krzysztof (Master thesis, 2016)This thesis presents an analysis of operating conditions in a refrigeration system located in supermarket Rema 1000 Prinsensgata, Trondheim (Norway). The main emphasis is put on a problem with oversized gas cooler, which ... -
Development of the natural working fluid‐based refrigeration system for domestic scale freeze‐dryer
Piechnik, Edyta; Smolka, Jacek; Palacz, Michał; Tolstorebrov, Ignat; Bodys, Jakub; Ciesielska, Agnieszka; Haida, Michal; Halski, Michal; Stebel, Michal; Melka, Bartlomiej; Nowak, Andrzej J.; Eikevik, Trygve Magne; Allymehr, Ehsan; Bantle, Michael; Claussen, Ingrid Camilla; Hoinka, Krzysztof; Milejski, Adam (Chapter, 2022)In this work, the analysis of the refrigeration system designed for the FrostX 10 freeze‐dryer is presented. The main goal of this study was to experimentally investigate the reference R452a freeze‐dryer and prepare ... -
HEM and HRM accuracy comparison for the simulation of CO2 expansion in two-phase ejectors for supermarket refrigeration systems
Palacz, Michal; Haida, Michal; Smolka, Jacek; Nowak, Andrzej J.; Banasiak, Krzysztof; Hafner, Armin (Journal article; Peer reviewed, 2017)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 ... -
Modified homogeneous relaxation model for the r744 trans-critical flow in a two-phase ejector
Haida, Michal; Smolka, Jacek; Hafner, Armin; Palacz, Michal; Banasiak, Krzysztof; Nowak, Andrzej J. (Journal article; Peer reviewed, 2017)The proposed modified homogeneous relaxation model (HRM) applied to the numerical model of a CO2 two-phase ejector was numerically investigated and developed based on the optimisation of the relaxation time (RT) correlation. ... -
Numerical investigation of heat transfer in a CO2 two-phase ejector
Haida, Michal; Smolka, Jacek; Hafner, Armin; Mastrowski, Mikolaj; Palacz, Michal; Madsen, Kenneth B.; Nowak, Andrzej J.; Banasiak, Krzysztof (Journal article; Peer reviewed, 2018)In this paper, the influence of heat transfer in the walls of an R744 two-phase ejector on ejector performance was investigated. A numerical investigation was performed using a computational fluid dynamic (CFD) model of ... -
Parallel Work of CO2 Ejectors Installed in a Multi-Ejector Module of Refrigeration System
Bodys, Jakub; Palacz, Michal; Haida, Michal; Smolka, Jacek; Nowak, Andrzej J.; Banasiak, Krzysztof; Hafner, Armin (Journal article; Peer reviewed, 2016)A performance analysis on of fixed ejectors installed in a multi-ejector module in a CO2 refrigeration system is presented in this study. The serial and the parallel work of four fixed-geometry units that compose the ... -
Performance mapping of the R744 ejectors for refrigeration and air conditioning supermarket application: A hybrid reduced-order model
Haida, Michal; Smolka, Jacek; Hafner, Armin; Ostrowski, Zeimowit; Palacz, Michal; Madsen, Kenneth B.; Försterling, Sven; Nowak, Andrzej J.; Banasiak, Krzysztof (Journal article; Peer reviewed, 2018)The continuous derivation of the ambient temperature and cooling demand in CO2 refrigeration and air-conditioning systems equipped with multi-ejector modules for supermarkets requires the analysis of the fixed ejector ... -
Performance operation of liquid ejectors for a R744 integrated multi-ejector supermarket system using a hybrid ROM
Haida, Michal; Smolka, Jacek; Hafner, Armin; Palacz, Michal; Ostrowski, Zeimowit; Bodys, Jakub; Kriezi, Ekaterini E.; Försterling, Sven; Nowak, Andrzej J.; Banasiak, Krzysztof (Journal article; Peer reviewed, 2019)Performance maps were generated for designed liquid ejectors installed in a multi-ejector module in an R744 integrated supermarket system using a hybrid of the reduced-order model (ROM). Hybrid ROMs of the investigated ... -
Shape optimisation of a two-phase ejector for CO2 refrigeration systems
Palacz, Michal; Smolka, Jacek; Nowak, Andrzej J.; Banasiak, Krzysztof; Hafner, Armin (Journal article; Peer reviewed, 2016)The shape optimisation of four CO2 ejectors is presented in this study. The considered ejectors were originally designed for a multi-ejector supermarket CO2 refrigeration system. The objective function was formulated to ... -
System model derivation of the CO2 two-phase ejector based on the CFD-based reduced-order model
Haida, Michal; Smolka, Jacek; Hafner, Armin; Ostrowski, Zeimowit; Palacz, Michal; Nowak, Andrzej J.; Banasiak, Krzysztof (Journal article; Peer reviewed, 2017)The developed reduced-order model (ROM) of the R744 two-phase ejector was presented in this paper. The proper orthogonal decomposition (POD) model was employed together with the radial basis function (RBF) to evaluate the ... -
The R744 multi-ejector hybrid CFD and experimentally-based reduced-order model
Haida, Michal; Smolka, Jacek; Hafner, Armin; Palacz, Michal; Ostrowski, Zeimowit; Madsen, Kenneth B.; Försterling, Sven; Nowak, Andrzej J.; Banasiak, Krzysztof (Chapter, 2018)The proposed hybrid reduced-order model (HROM) of the four R744 fixed ejectors installed in the multiejector module is presented. The ejectors HROM was built by use of the proper orthogonal decomposition together with the ...