Blar i NTNU Open på forfatter "Hafner, Armin"
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A CFD analysis for the performance assessment of a novel design of plates-in-tank latent storage unit for freezing applications
Selvnes, Håkon; Allouche, Yosr; Sevault, Alexis; Hafner, Armin (Chapter, 2019)In this paper, the charging and discharging processes of a recently developed cold thermal energy storage (CTES) unit integrated into a poultry processing plant is investigated. A mathematical model of the CTES was created ... -
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 ... -
A novel PCM accumulator for refrigerated display cabinet : design and CFD simulations
Sevault, Alexis; Banasiak, Krzysztof; Bakken, Jørn; Hafner, Armin (Chapter, 2018) -
A review on recent technological advancements in multi-ejector concept
Gullo, Paride; Hafner, Armin; Banasiak, Krzysztof; Minetto, Silvia (Chapter, 2018)As a consequence of the coming into force of the EU F-Gas Regulation 517/2014, enormous technological developments have been experienced on the part of transcritical R744 supermarket refrigeration systems. These have led ... -
A steady and quasi-steady state analysis on the CO2 hybrid ground-coupled heat pumping system
Jin, Zhequan; Eikevik, Trygve Magne; Nekså, Petter; Hafner, Armin (Journal article; Peer reviewed, 2017)This article contains the steady and quasi-steady state analysis on a CO2 hybrid ground-coupled heat pumping system for warm climates. The hybrid system uses a combination of ambient air and ground boreholes as a heat sink ... -
Advanced experimental analysis of a small-scale prototype with noble gases for the future upgrade of the detector cooling system at CERN
Jerve, Frida (Master thesis, 2023)Som en del av High-Luminous oppgraderingen av Large Hadron Collider ved CERN i 2026, er det nye krav til kjøling av detektorene i interaksjonspunktene. Det nåværende systemet bruker CO₂ som kjølemiddel, og de nye kravene ... -
Advanced R744 solution for supermarkets, hotel chillers and maritime applications in India
Singh, Simarpreet; Selvnes, Håkon; Pardiñas, Ángel Á.; Reddy, Srinevas K; Gupta, P; Vaishak, S; Arun, B.S.; Widell, Kristina Norne; Elarga, Hagar; Hafner, Armin (Chapter, 2022)R744 integrated systems can meet oscillating heating and cooling demands efficiently and become a game changer in countries such as India. The present work aims to develop and present R744 system designs and disseminate ... -
Advantage of CO2 heat pump chiller for the application in Indian hotels
Reddy, Y. Siva Kumar; Elarga, Hagar Hassan Hassanein Hassan; Gururchethan, A.M.; Maiya, M.P.; Hafner, Armin (Chapter, 2023)Hotels in India conventionally use diesel-fired hot water generators to meet hot water demands at 46°C. These are inefficient and also release high emissions. This study focuses on the energy saving and emission reduction ... -
Air reversing CO2 heat pumps
Andreassen, Hanne Elisabeth Bø (Master thesis, 2010)CO2 is an environmentally friendly refrigerant that has a no global warming potential when used as refrigerant. The current refrigerants used for air conditioning in public transport are chemical components, and have a ... -
Analysis of R744 refrigeration system with liquid ejectors
Singh, Simarpreet; Reddy, Amshith; Parkash, Maiya M.; Banasiak, Krzysztof; Hafner, Armin; Nekså, Petter (Chapter, 2018)In recent years, there is a rapid increase in the cooling demand. Hence, not only the consumption of energy, but also the quantity of the refrigerants released into the air is increasing globally leading to planetary ... -
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 ... -
ANN modelling of CO2 refrigerant cooling system COP in a smart warehouse
Opalic, Sven Myrdahl; Goodwin, Morten; Lei, Jiao; Nielsen, Henrik Kofoed; Pardiñas, Ángel Á.; Hafner, Armin; Kolhe, Mohan Lal (Peer reviewed; Journal article, 2020)Industrial cooling systems consume large quantities of energy with highly variable power demand. To reduce environmental impact and overall energy consumption, and to stabilize the power requirements, it is recommended to ... -
Annual energy performance of R744 and R410A heat pumping systems
Jin, Zhequan; Eikevik, Trygve Magne; Nekså, Petter; Hafner, Armin; Wang, Ruzhu (Journal article; Peer reviewed, 2017)This work compares the annual energy performance of heat pumping systems using R744 and R410A as refrigerant. Focus is the annual energy efficiency of R744 hybrid ground-coupled heat pumping system. The hybrid system uses ... -
Application of a Novel Two-Stage Evaporator in Air-Conditioning Applications
Köster, Lukas (Master thesis, 2023)Det foreliggende arbeidet undersøker anvendelsen av en ny totrinns fordamper i kombinasjon med et avansert hydronisk delsystem for å dekke luftkondisjoneringsbehov. Den foreslåtte systemarkitekturen består av en totrinns ... -
Application of natural refrigerants in the industrial refrigeration and heat pumps in the future
Pachai, Alexander C.; Hafner, Armin; Ciconkov, Risto (Chapter, 2022)For more than 150 years natural refrigerants have been used in various industrial applications reaching temperatures from -273°C to more than 300°C and the level of the high temperature limit is difficult to estimate at ... -
Application Of Refrigeration Technologies For Energy Efficient Production Of Fish Protein Hydrolysates
Sherman, Prem Kumar; Tolstorebrov, Ignat; Widell, Kristina Norne; Hafner, Armin; Nordtvedt, Tom Ståle (Chapter, 2022)Fish protein hydrolysate (FPH) is one of the most efficient and sustainable way to recover the valuable nutrients from fish remaining materials and has a widespread application. However, the production of FPH demands ... -
Attaining a higher flexibility degree in CO2 compressor racks
Álvarez Pardiñas, Ángel; Contiero, Luca; Hafner, Armin; Banasiak, Krzysztof; Larsen, Lars F.S. (Chapter, 2020)CO2 compressor racks have shown their suitability for commercial and industrial refrigeration systems at any location and climate. Even if some references state that CO2 units can compete in capital cost with any other ... -
CFD modeling of ice formation and melting in horizontally cooled and heated plates
Selvnes, Håkon; Allouche, Yosr; Sevault, Alexis; Hafner, Armin (Chapter, 2019)This paper investigates the ice formation and melting processes in a novel CTES unit using the commercial CFD software ANSYS Fluent 19. The storage unit is designed to operate as a peak shaving device integrated into the ... -
CFD Modelling for Improved Components in CO2 and Ammonia Vapour Compression Systems
Ringstad, Knut Emil (Doctoral theses at NTNU;2023:180, Doctoral thesis, 2023)Refrigeration and heat-pumping systems are shifting to natural, environmentallyfriendly refrigerants like CO2 to combat global warming. Ejectors are often used in these systems for expansion work recovery to enhance ... -
CFD-based design algorithm for CO2 ejectors
Ringstad, Knut Emil; Banasiak, Krzysztof; Hafner, Armin (Chapter, 2021)In this work, a novel CFD-database generation algorithm for CO2 ejectors are presented. The algorithm is explained and its details discussed. A case for CFD database generation is then performed based on an ejector design ...