Search for dissertations about: "R134a"

Showing result 1 - 5 of 10 swedish dissertations containing the word R134a.

  2. 1. HFC Mixtures as Replacement for HCFC-22 in Large-Scale Heat Pumps and Chillers

    Author : Cecilia Gabrielii; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; R404A; R143a; R125; performance; R134a; R32; replacement; zeotropic HFC mixtures; simulations; design; measurements; chiller; R407C; condenser evaporator; screening; optimization; heat pump; R22;

    Abstract : Replacement of the conventional refrigerant HCFC-22 (R22) is one of the urgent issues to be solved within the scheduled time-frame of the international regulation of the HCFCs. Since there exists no pure fluid that can replace R22 in the same general way as HFC-134a (R134a) is a replacement for CFC-12, HFC mixtures are suggested as possible substitutes. READ MORE

  4. 2. Flow boiling of ammonia and propane in mini channels

    Author : Muhammad Hamayun Maqbool; Björn Palm; Rahmatollah Khodabandeh; Satish Kandlikar; KTH; []
    Keywords : Flow Boiling; Mini channels; Global Warming Potential; Ammonia; Propane; R134a; HFC; Two-phase; Heat Transfer; Pressure Drop; Dry out.;

    Abstract : The environmental concerns in recent times have grown especially after signing Montreal protocol. In the last ten years, researchers have focussed mainly on understanding the boiling and condensation phenomena of HFC refrigerants in minichannels. READ MORE

  5. 3. Flow boiling heat transfer, pressure drop and dryout characteristics of low GWP refrigerants in a vertical mini-channel

    Author : Zahid Anwar; Björn Palm; Rahmatollah Khodabandeh; Maria Fernandino; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Mini micro-channels; R1234yf; R152a; R600a; R134a; Boiling heat transfer; Pressure drop; Dryout; Correlation;

    Abstract : Two-phase heat transfer in mini/micro-channels is capable of meeting the high cooling demands of modern high heat flux applications. The phase change process ensures better temperature uniformity and control for local hot spots. Furthermore, these compact channels could be helpful in reducing the required charge and material inventories. READ MORE

  6. 4. Phase-out of refrigerant R22

    Author : Anders Johansson; KTH; []
    Keywords : Retrofit; Phase-out; CFC; HCFC; HFC; R22; R407C; R417A; R404A; R134a; Ozone depletion; Zeotropic refrigerant mixture; Circulated composition; Measurement; Energy; Energy efficiency; System; Systems analysis; Modelling; Simulation; Prediction;

    Abstract : .... READ MORE

  7. 5. Enhanced Boiling Heat Transfer on a Dendritic and Micro-Porous Copper Structure

    Author : Richard Furberg; Björn Palm; Vishwas Wadekar; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; enhanced boiling; R134a; FC-72; flow boiling; heat transfer; high speed visualization; instability; micro-channels; micro-structured; nano- and micro-technology; nano- and micro-porous structured surfaces; plate heat exchanger; pool boiling; porous media; thermosyphon; two-phase heat transfer; SRA - Energy; SRA - Energi;

    Abstract : A novel surface structure comprising dendritically ordered nano-particles of copper was developed during the duration of this thesis research project. A high current density electrodeposition process, where hydrogen bubbles functioned as a dynamic mask for the materials deposition, was used as a basic fabrication method. READ MORE