Browsing NTNU Open by Author "Hafner, Armin"
Now showing items 101-120 of 238
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Experimental investigation of CO2 systems for Indian supermarkets with parallel configuration of multiejectors (INDEE)
Banasiak, Krzysztof; Singh, Simarpreet; Hafner, Armin; Maiya, Prakash; Nekså, Petter; Pardiñas, Ángel Á. (Chapter, 2019)Experimental investigation of transcritical R744 pack for Indian supermarkets was performed. Parallel combination of expansion work recovery multiejector blocks was applied for optimization of energy performance of the ... -
Experimental Investigation of evaporation of propane (R290) in small pipes
Allymehr, Ehsan (Master thesis, 2018)This master thesis discusses the two-phase boiling pressure drop and heat transfer characteristics of propane in different test conditions in an experimental setup. One smooth tube with inside diameter of Di=4.2 mm was ... -
Experimental investigation on integrated two-stage evaporators for CO2 heat-pump chillers
Hafner, Armin; Hazarika, Mihir Mouchum; Lechi, Federico; Zorzin, Alvaro; Pardiñas, Ángel Á.; Banasiak, Krzysztof (Chapter, 2022)In this experimental study the performance of novel compact evaporator configuration was investigated. What makes this evaporator configuration unique is the integration of a gravity-fed/ self-circulation evaporator loop ... -
An experimental study of an ejector-boosted transcritical R744 refrigeration system including an exergy analysis
Elbarghthi, Anas F.A.; Hafner, Armin; Banasiak, Krzysztof; Dvorak, Vaclav (Peer reviewed; Journal article, 2021)The field of refrigeration witness a massive transition in the supermarket with a strong focus reflected on energy consumption. The use of ejector allows for overcoming the significant exergy destruction lays on the expansion ... -
Experimental study of Isobutane (R600a) evaporation in microfinned and smooth tubes
Allymehr, Ehsan; Roux, Marie Isabelle; Álvarez Pardiñas, Ángel; Eikevik, Trygve Magne; Hafner, Armin (Chapter, 2020)Heat transfer coefficient and pressure drop of Isobutane (R600a) in an internally enhanced tube has been experimentally measured and compared to a smooth tube with the same outer diameter of 5 mm. The effects of mass flux ... -
Experimental study of the heat transfer problem in expansion devices in CO2 refrigeration systems
Mastrowski, Mikolaj; Smolka, Jacek; Hafner, Armin; Haida, Michal; Palacz, Michal; Banasiak, Krzysztof (Journal article; Peer reviewed, 2019)Two expansion devices designed for CO2 refrigeration systems namely, capillary tube and fixed-geometry ejector were experimentally tested in the SINTEF/NTNU laboratory in Trondheim, Norway to determine the influence of ... -
Experimental Study on the Integration of a Novel Two-Stage Evaporator in a CO2 Heat Pump Chiller
Hafsås, Johan (Master thesis, 2023)I denne masteroppgaven er det blitt utført eksperimentelle forsøk på en ny totrinns fordamper integrert i et transkritisk CO2-kjøleanlegg. Motivet for forsøkene er å se på muligheten for å forbedre energieffektiviteten i ... -
Experimental testing and development of CO2 compressors: Eksperimentell utprøving og utvikling av CO2 kompressorer
Ask, Anders (Master thesis, 2012)CO2 is a natural refrigerant and is well suitable in many cooling applications. It has been used within the refrigeration industry from the 1900s, but got replaced as the synthetic refrigerants got introduced. In 1990 these ... -
Feasibility study for upgrading the current heat distribution network of an existing building complex to a Smart Thermal Grid
Clauss, John (Master thesis, 2015)A feasibility study on upgrading an existing heat distribution network to a low-temperature distribution grid has been carried out during this project. The integration of a solar thermal system combined with a borehole ... -
Field data of CO2 integrated refrigeration, heating and cooling systems for supermarkets
Tosato, Giacomo; Minetto, Silvia; Rossetti, Antonio; Hafner, Armin; Schlemminger, Christian; Girotto, Sergio (Chapter, 2020)The EU H2020 project MultiPACK has given the opportunity of installing three state-of-the art CO2 systems for supermarkets in South Europe, able to supply all the required thermal energy needs of the site, i.e. refrigeration, ... -
General heat transfer correlations for supercritical carbon dioxide heated in vertical tubes for upward and downward flows
Ye, Zuliang; Zendehboudi, Alireza; Hafner, Armin; Cao, Feng (Peer reviewed; Journal article, 2022)Supercritical CO2 is a promising working fluid for many industrial applications. To improve the performances of relevant components and systems, the prediction of the heat transfer of supercritical CO2 is an important ... -
Heat pump/chiller system for centralized kitchens in India
Singh, Simarpreet; Hafner, Armin; Banasiak, Krzysztof; Seshadri, Satyanarayanan; Maiya, Prakash; Smitt, Silje Marie; Gabrielii, Cecilia H (Chapter, 2020)A heat pump unit using CO2 as working fluid is designed to meet not only a part of the heating demand in the centralised kitchen at The Akshaya Patra Foundation, Bengaluru, India, but also the entire cooling demand to ... -
Heat transfer and pressure drop of supercritical CO2 in brazed plate heat exchangers of the tri-partite gas cooler
Zendehboudi, Alireza; Ye, Zuliang; Hafner, Armin; Andresen, Trond; Skaugen, Geir (Peer reviewed; Journal article, 2021)The heat transfer characteristic of supercritical CO2 is an essential research topic due to its significant influence on the performance of heat exchangers and systems. In this paper, the heat transfer and pressure drop ... -
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 ... -
Höchtemperatur-Wärmepumpen mit natürlichen Kältemitteln : Fallstudien zur HTWP-Integration für industrielle Kälte- und Prozessheisswasserherstellung
Schlemminger, Christian; Ahrens, Marcel Ulrich; Foslie, Sverre Stefanussen; Moen, Ole Marius; Bantle, Michael; Hafner, Armin; Jenssen, Sigmund (Chapter, 2021)Thermische Prozesse in der Nahrungsmittelindustrie, wie z. B. Molkereien sind oftmals eine Kombination aus Erwärmung und Abkühlung eines Produktes. Prozesskühlung wird dabei meistens mittels einer Wärmepumpe erzielt, wobei ... -
Identification of Existing Challenges and Future Trends for the Utilization of Ammonia-Water Absorption–Compression Heat Pumps at High Temperature Operation
Ahrens, Marcel Ulrich; Loth, Maximilian; Tolstorebrov, Ignat; Hafner, Armin; Kabelac, Stephan; Wang, Ruzhu; Eikevik, Trygve Magne (Peer reviewed; Journal article, 2021)Decarbonization of the industrial sector is one of the most important keys to reducing global warming. Energy demands and associated emissions in the industrial sector are continuously increasing. The utilization of high ... -
Improvement of energy efficiency in a brewery
Taguas Garzón, Francisco Javier (Master thesis, 2018)The implementation and performance of an innovative surplus heat recovery system in a brewery are analyzed in this Thesis. An energy balance of the flows present in the plant was performed, and focus was given to determining ... -
Industrial High Temperature Heat Pump with natural Refrigerants - Performance evaluation and design improvement
Trumpf, Hannes (Master thesis, 2022)Abstract will be available on 2025-09-01 -
Innovative reheat approach of the TES system during the hotel’s standstill operation utilizing a CO2 heat pump/chiller unit
Elarga, Hagar Hassan Hassanein Hassan; Pardiñas, Ángel Á.; Minetto, Silvia; Hafner, Armin (Chapter, 2023)The implementation of CO2 as a refrigerant is considered one of the solutions to improve the overall building’s energy performance, especially if the heat recovery concept is applied. In this paper, an innovative approach ... -
Integrated CO2 refrigeration and heat pump systems for dairies
Selvnes, Håkon; Jenssen, Sigmund; Sevault, Alexis; Widell, Kristina Norne; Ahrens, Marcel Ulrich; Ren, Shuai; Hafner, Armin (Chapter, 2022)Production facilities in the food industry are large consumers of electricity and thermal energy due to energyintensive processes such as steam production, cleaning, sanitising, refrigeration and drying. Furthermore, there ...