• Characteristics of evaporation of propane (R290) in compact smooth and microfinned tubes 

      Allymehr, Ehsan; Pardiñas, Ángel Á.; Eikevik, Trygve Magne; Hafner, Armin (Peer reviewed; Journal article, 2020)
      Evaporation of flowing propane and the effect of enhanced geometry on heat transfer coefficient and pressure drop is experimentally investigated. One smooth tube and two microfinned tubes with an outer diameter of 5 mm ...
    • Comparative analysis of evaporation of isobutane (R600a) and propylene (R1270) in compact smooth and microfinned tubes 

      Allymehr, Ehsan; Pardiñas, Angel A.; Eikevik, Trygve Magne; Hafner, Armin (Peer reviewed; Journal article, 2021)
      Data base for evaporation of flowing isobutane and propylene in compact internally enhanced surfaces is extended by experimental tests in two microfinned tubes and a smooth tube. The outer diameter for all of the test tubes ...
    • 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 ...
    • 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 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 ...
    • Investigation of Hydrocarbon Two-phase Flow for Charge Reduced Heat Exchangers 

      Allymehr, Ehsan (Doctoral theses at NTNU;2021:397, Doctoral thesis, 2021)
      Hydrocarbons off er an alternative to the HVAC industry as a natural working fluid with minimal environmental impact. The main challenge with hydrocarbons utilization is flammability which can be mitigated by reduction of ...
    • Numerical Study of Hydrocarbon Charge Reduction Methods in HVAC Heat Exchangers 

      Allymehr, Ehsan; Skaugen, Geir; Will, Torsten; Pardiñas, Ángel Á.; Eikevik, Trygve Magne; Hafner, Armin; Schnabel, Lena (Peer reviewed; Journal article, 2021)
      Required refrigerant charge in heat pump systems with propane is analyzed. Two systems are compared: The first a direct heat pump, with fin-and-tube heat exchangers, and the second an indirect system, with plate heat ...