OBJECTIVE To compare the bronchodilator effectiveness of albuterol reformulated in the chlorofluorocarbon-free propellant hydrofluoroalkane (HFA)134a (Proventil HFA) to that of Ventolin and HFA placebo over 12 weeks of regular dosing. DESIGN Randomized, double-blind, double-dummy, parallel group, placebo-controlled, multi-center trial of asthmatics requiring inhaled beta-adrenergic bronchodil...

SUMMARY This paper is one input to respond the Council request of 10 October 2000 to " study and prepare measures in reduction of all greenhouse gas emissions from air conditioning in vehicles ". Greenhouse gas emissions due to mobile air conditioning are significant and growing fast in the European Union. The European Commission estimates that the emission will be between 31 and 53 Mt CO 2 eq ...

The awareness to protect the environment from the harmful effects of CFCs has motivated the refrigeration scientists and engineers to study alternative refrigerants to replace the CFCs even in the existing units. This paper presents a thermodynamic study of hydrocarbon blends (Propane/lsobutane) and blends of HFC-134a-HC-600a as a possible "drop-in" (some electrical component to be changed to m...

This research studies the influence of using SiO2 nano-particles 50nm in a Vapor Compression Refrigeration System (VCRS), along with Poly-alkylene Glycol (PAG) oil and R-134a mixed to create nano-refrigerant. In this work, were performed three different concentrations (0.1%, 0.3%, 0.5%) 200ml PAG oil. AVCR system was built at mechanical engineering department laboratory Al-Qadisiyah University ...

Solubility (vapor pressure) , viscosity and density have been experimentally determined for thirty-five potential refrigeration working fluids. Properties for low refrigerant concentration mixtures (0, 10, 20 and 30 weight percent refrigerant) were determined over the temperature range 0 to IOO•C (32 to 212"F) or to the critical temperature of the refrigerant, and pressure range 0 to 3,500 kPa ...

Heat transfer coefficient data was taken during in-tube evaporation of five differenct refrigerant mixtures. These measurements were performed in a 318" O.D. (9.7 mm) smooth copper tube at refrigerant temperatures of -zoe and 4°C. Four different mass fluxes ranging from 125 to 375 kg/s-m2 were tested. On a mass basis, the five different mixtures tested were: R-125 (40%) I R-32 (60%), R-32 (30%)...

A series of tests has been completed comparing the system performance of four long term replacements HP62 (44% R~125/ 54% R-143a/ 4% R-134a), AZ-50 (50% R-125/ 50% R-143a), Klea 60 (20% R-32/ 40% R-125/ 40% R-134a), and Klea 61 (1 0% R-32/ 70% R-125/ 20% R-134a) as potential alternatives for the CFC-containing low temperature refrigerant R-502. The tests were carried out under controlled condit...

A household refrigerator designed to work with R-134a was used as an investigation unit to assess the prospect of using mixed refrigerants. The recital of the refrigerator using mixed refrigerant was investigated and compared with the performance of refrigerator when R-134a was used as refrigerant. The effect of condenser temperature and evaporator temperature on COP, refrigerating effect was i...

An Exergy method for theoretical analysis of a traditional vapour-compression refrigeration system equipped with liquid vapour heat exchanger (lvhe) for HFO-1234yf (2, 3, 3, 3-Tetrafluoropropene) and HFO-1234ze (trans-1, 3, 3, 3-tetrafluoroprop-1-ene), both ultra low Global Warming Potential(GWP) and zero Ozone Depletion Potential(ODP) refrigerants and comparison of the results with HFC-134a re...

R-134a (C2H2F4) is a low cost, easily available and chlorine free refrigerant, which in its superheated state can be used as an efficient neutron detector. Due to its high solubility in water the R-134a based superheated droplet detectors (SDD) are usually very unstable unless the detector is fabricated using a suitable additive, which stabilizes the detector. The SDD is known to have superheat...