ABSTRACT
This work presents findings on utilizing the expansion stage of compressed air energy storage systems for air conditioning purposes. The proposed setup is an ancillary installation to an existing compressed air energy storage setup and is used to produce chilled water at temperatures as low as 5 °C. An experimental setup for the ancillary system has been built with appropriate telemetric devices to measure the temporal temperature variation, which consequently can be used to calculate the heat transfer and available cooling capacity. The system is compared to commercially available compression cooling air conditioners, and the potential of replacing them is promising, as one ton of conventional cooling can be replaced with a 500-L (0.5 m3) air tank at 20 bar operating for an hour. More tanks can be added to extend the operational viability of the system, which is also serving the original purpose of storing energy from grid excess or from solar photovoltaic panels. The thermal management has had the added benefit of increasing the roundtrip efficiency of the storage system from 31.4 to 35.2%, along with handling a portion of the cooling load.
ABSTRACT
OBJECTIVE: To identify the most common liver pathologies seen in our center, to find the prevalence of advanced fibrosis and cirrhosis in patients with chronic hepatitis B and C, and to correlate the histological and laboratory features of the most common diseases and compare between them. METHODS: Liver biopsy procedures performed in our Gastroenterology Unit at King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia were traced from records between the years 1997-2003. Clinical, histopathological, and laboratory features were recorded. RESULTS: We identified 574 liver biopsies during the study period. Of the 502 included patients, males were 58.6%. The mean age of the patients was 43.5 years. Approximately half of the biopsies (49%) were performed for patients with hepatitis C, followed by hepatitis B, for which 17% of the biopsies were performed. Patients with hepatitis B were approximately 10 years younger than patients with hepatitis C (p = 0.01). They were 10% more likely to be males. In terms of fibrosis, only approximately 17% of patients with hepatitis B and 27% of patients with hepatitis C had advanced fibrosis. CONCLUSION: Most liver biopsies performed in our center are performed for patients with hepatitis C. Rates of advanced fibrosis in our series are significantly lower than what was previously reported in other studies.
