Sökning: "refrigerants"

Visar resultat 11 - 15 av 33 avhandlingar innehållade ordet refrigerants.

  1. 11. Measurements and Modelling of Convective Vaporization for Refrigerants in a Horizontal Tube

    Författare :Peter Melin; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; n-butane; HFC134a; pressure drop; propane; HFC143a; horizontal flow boiling; in-tube vaporization; HFC125; HFC32; experimental study; HCFC142b; HCFC22; non-azeotropic mixtures; CFC12; modelling; mixture effects;

    Sammanfattning : An evaporator facility has been constructed to measure local values of heat transfer and pressure drop. The evaporator resembles a normal working evaporator tube in a direct-expansion evaporator applicable to large heat pump/refrigeration cycles, typically over 500 kW. The evaporator is brine-heated and uses an expansion valve to control the inlet. LÄS MER

  3. 12. Solubility of HFC Refrigerants in Long-Chained Hydrocarbons and Pentaerythritol Esters Measurements and Development of Predictive Models

    Författare :Åsa Wahlström; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Restrictions for environmental reasons on the use of CFCs and HCFCs, the traditional working fluids in heat pumps, refrigeration plants and air conditioning, have led to the use of pure HFCs and blends of HFCs. However, since HFCs have a different influence on compressor oils, new oils that are compatible with HFCs need to be found. LÄS MER

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

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

    Sammanfattning : 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. LÄS MER

  5. 14. Elastohydrodynamic lubrication and lubricant rheology in refrigeration compressors

    Författare :Ulf Jonsson; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Maskinelement; Machine Elements;

    Sammanfattning : The introductory chapter gives a general description of the lubrication of rolling element bearings in refrigeration compressors and rheological properties of oil-refrigerant mixtures. The influence of refrigerants on the viscosity, pressure-viscosity coefficient and film forming ability in a EHD-contact is described. LÄS MER

  7. 15. Flow boiling of ammonia and propane in mini channels

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

    Sammanfattning : 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. LÄS MER