In order to find proper lubricants for HFC-134a compressor system, many polar compounds have been synthesized and evaluated. Among such compounds, polyalkylene glycol (PAG) derivatives and carboxylates (esters) have been identified as candidates for car air· conditioners and for refrigerators respectively.',.') However, it is dear that these amdidates have weaknesses: PAGs • demonstrate poor mi...

Tests were run with both R-12 and R-l34a in a water calorimeter. Refrigerant 12 was run with mineral oil as the lubricant. Evaporating and condensing heat transfer coefficients were calculated over a range of temperatures. To evaluate the impact of the lubricant on the heat transfer coefficients, a oil separator was added. Tests were then run with the oil separator over the same temperature ran...

STUDY OBJECTIVE s: To compare the effect of 4 weeks of treatment with fluticasone propionate (FP), 100 micro g bid, delivered either via the Diskhaler (GlaxoSmithKline; Middlesex, UK) or a hydrofluoroalkane (HFA)-134a pressurized metered-dose inhaler (pMDI) on airway responsiveness. DESIGN A single-center, randomized, double-blind, double-dummy, placebo-controlled crossover study. SETTING O...

In this study, condensation heat transfer coefficients (HTCs) of HCFC22, HCFC123, HFC134a and HFC245fa are measured on a horizontal plain tube 19.0 mm outside diameter. All data are taken at the vapor temperature of 39 with a wall subcooling temperature 3-8 . Test results show the HTCs of newly developed alternative low vapor pressure refrigerant, HFC245fa, on a smooth tube are 9.5% higher than...

In accordance with worldwide consensus, the use of chlorofluorocarbons, which play an important role in damaging the ozone layer, should be completely abolished by the end of 1995. This provided the impetus for developing the three vane rotary compressor. Formerly CFC-12 was used as the refrigerant in automotive air conditioners, until HFC-134a was substituted for CFC-12. In response to the cha...

This work presents results from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) study. Whole air samples were obtained on board research flights that flew over California during June 2008 and analyzed for selected volatile organic compounds, including several halogenated species. Samples collected over the South Coast Air Basin of California ...

Hydro-fluorocarbons (HFCs) that are not harmful to ozone layer and used in many appli-cations, including as refrigerants, aerosols, solvents blowing agents for insulating foams replace chlorofluorocarbons hydro (HCFCs). However, some HFCs have a high GWP, which stands “Global Warming Potential(GWP).” Because of the grow-ing concern over global climate change, researchers paying closer attention...