HFC-245fa Research Articles

Environmental and thermal benefits of linking Brayton, absorption chiller, and organic Rankine cycles with low-enthalpy geothermal source at an arid-zone area of Libya

A combined system which consists of Brayton, LiBr/H2O absorption chiller, and HFC 245fa organic Rankine cycles has been developed and linked to a high potential low-temperature geothermal source of energy. Situated in an arid-zone area at Waddan City Libya, the geothermal source could provide sufficient energy for the City and surrounding villages and satisfy their full electrical demand of 100 MW in an uninterrupted and stable way. The system could also supply district heating and hot water. The simulated results show that the output power and thermal efficiency of the combined cycles were improved by 5 per cent and 1.5 per cent, respectively, compared to a standalone gas turbine and it also reduced carbon emissions by 55.7 per cent (291 g/kWh instead of 649 g/kWh). Incorporating district heating to the electrical energy raised the energy utilization factor to 55.1 per cent.

Polyurethane foams blown with various types of environmentally friendly blowing agents

Three different types of environmently friendly blowing agents (HFC 365mfc, HFC 245fa and water) have been used to fabricate rigid polyurethane foams from crude methylene diphenyl diisocyanate and polypropylene glycols. Water induced the earliest bubble, temperature and pressure rises, whereas HFC 365mfc gave the slowest reactivity. Water blown foams showed the largest cell and the lowest density and compression strength, together with the highest glass transition temperature and the greatest dimensional stalibility at high temperature. With the combined effects of large cell and large thermal conductivity of CO2, water blown foam gave the highest conductivity of the foam. On the other hand, HFC 365mfc gave the smallest cell size, the greatest foam density and compression strength, whereas HFC 245fa gave the intermediate values, except the lowest thermal conductivity of the foam.

Hydrofluorocarbon 245fa: A Versatile New Synthon in Alkyne Chemistry.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The acute, genetic, developmental, and inhalation toxicology of 1,1,1,3,3-pentafluoropropane (HFC 245fa).

1,1,1,3,3-Pentafluoropropane (HFC 245fa) is a volatile, low boiling liquid. It was inactive in a reverse mutation (Ames) assay using five strains of Salmonella typhimurium and one strain of Escherichia coli. It was also inactive in an in vivo mouse micronucleus assay with exposures of 101,000 ppm. In a chromosome aberration study with human lymphocytes, some activity was seen when cell cultures were exposed to atmospheres of 30% v/v or higher for 24 h without metabolic activation. No activity was seen in assays using less than 30% v/v or exposure times of less than 24 h. No activity was seen in the presence of metabolic activation even with exposures of 70%. It was not toxic by the dermal route. There was no mortality or significant signs of toxicity when rats and mice were given 4- h exposures to levels of 203,000 ppm or 101,000 ppm of HFC 245fa, respectively. In a cardiac sensitization study with dogs involving intravenous administration of epinephrine, the no observed effect level (NOEL) was 34,000 ppm and the threshold for a response was 44,000 ppm. In a rat inhalation, developmental toxicity study, a slight reduction in pup weight was seen at 50,000 ppm, but not at 10,000 ppm. There were no developmental effects at any level. A series of three inhalation toxicity studies were conducted. All involved daily 6-h exposures up to 50,000 ppm. The first study involved 14 consecutive snout-only exposures. There were no treatment-related effects on body weight, survival, or histologic parameters. BUN, GPT, and GOT levels frequently were elevated compared to controls , whereas cholesterol levels tended to be lower. The second study involved 28 consecutive whole-body exposures. Again, there were no treatment related effects on body weight, survival, or histological parameters. Urine volume was increased. Increases were also seen in several red blood cell parameters. These may be related to partial dehydration. Increases were seen in BUN levels and alkaline phosphatase (AP), GPT, GOT and CPK activities, primarily in rats exposed at 10,000 and 50,000 ppm. Urinary fluoride levels were also elevated in an exposure- related pattern. In the third study, whole-body exposures were conducted 5 days per week for 13 weeks. There were no treatment-related effects on survival, clinical observations, body weight gain, or food consumption. Urine volumes were increased, urinary fluoride levels were elevated, and increases were seen in red blood cell counts, and related parameters and increases were seen in AP, GOT, GPT and CPK activities. These effects were seen in the 10,000 and 50,000 ppm exposure level groups. Histopathologic examination did not show any effects on the kidney, liver, or lungs. There was an increased incidence of myocarditis in all animals exposed at 50,000 ppm and the majority exposed at 10,000 ppm. It was described as mild. Based on these findings, 2000 ppm appears to be a no observed adverse effect level.