Thermodynamic Analysis of Effects of the Inlet Air Cooling on Cycle Performance in Combined Brayton-Diesel Cycle

In the present study, the effects of inlet air cooling on compound cycle performance in a diesel gas turbine engine system where waste heat is used in the composite power system in the sustainable energy system were investigated thermodynamically. The effects of the inlet air cooling the system that enhances power production and the resulting thermal efficiency values were analyzed based on various operational variables gas turbine pressure ratio, diesel engine compression ratio, gas turbine inlet and fresh air inlet temperatures, etc. . The energy losses in each system component were determined and the second law efficiency of the system was determined based on the introduced operational parameters. The gas turbine unit in the model included a gas generator with two compressors and a high-pressure turbine, and a low-pressure power turbine running on a separate shaft. The diesel engine and gas-generator exhaust gases were mixed and expanded in a low-pressure turbine, leading to the production of power with the waste energy. In the cycle, an intake air cooler, an intercooler and a recuperative air pre-heater were used. In the intake air cooling cycle, the power increase was around 15% when the pressure rate of the low-pressure compressor was 3.5. Natural gas was used as fuel in the thermodynamic model. The cycle irreversibilitywas used in the calculations based onthe thermodynamic concepts

Lactoferrin in Gingival Crevicular Fluid and Peripheral Blood during Experimental Gingivitis

Objectives Lactoferrin (LF) is an iron binding protein and stored in the specific granules of granulocytes. It is released by degranulation following granulocyte activation. A positive correlation was previously reported between periodontitis and LF titers of gingival crevicular fluid (GCF) and blood. The purpose of this study was to examine alterations of GCF and blood levels of LF (LF-GCF and LF-BL, respectively), employing the experimental gingivitis model. Methods Twelve systemically healthy volunteers, aged 19–21, were selected. Pre-experimental phase of hygiene was followed by a 14-day experimental gingivitis phase in which subjects refrained from all oral hygiene procedures. After that subjects resumed optimal plaque control for 21 days of recovery period. At days 0 (baseline), 14 and 35 gingival crevicular fluid (GCF) and blood samples were collected and plaque index (PI), gingival index (GI), bleeding on probing (BOP) and probing pocket depth scores were recorded. LF levels were measured with commercial enzyme-linked immunosorbent assay (ELISA) kit. Results PI, GI, BOP and LF-GCF increased significantly after 14 days of experimental gingivitis period and decreased significantly after reinstitution of oral hygiene measures (P<.05). LF-BL appeared to follow the same pattern. Significant negative correlation was detected between the level of LF-BL and BOP at day 14 (P<.05), whereas significant positive correlation was noticed between LF-BL and clinical scores PI, GI and BOP at day 35 (P<.05). Conclusions LF-BL followed the same pattern with LF-GCF and clinical scores during the experimental gingivitis and recovery periods, although alterations of the LF-BL appeared statistically insignificant.PubMe

An investigation of the Performance of a Conical Solar Water Heater in the Kingdom of Bahrain

Domestic water heater corresponds to 25% of the house energy consumption and can play an important role to reduce energy house expenses. Solar energy offers a preferred renewable energy resource because of its economic and environmental advantages. It is considered the best alternative to reduce domestic water heater energy consumption cost. Converting solar energy into heat can be considered among the simplest used systems. Solar thermal conversion is more efficient than solar electrical direct conversion method. Solar water heater systems are particularly easy to use and to repair. The integrated conical solar collector water heater (ICSCWH) is so far the easiest among water heating systems. The ICSCWH converts directly and efficiently the solar flux into heat. In order to expand the utilization of ICSCWH systems, many design modifications have been examined and analyzed. This study provides an experimental investigation and mathematical simulation of an ICSCWH system equipped with a glass cover resulting in the increase of the maximum absorption. Integrating the cone-shaped heat collector with an aluminum spiral pipe flow system may enhance the efficiency of the proposed system. In order to maximize the solar radiation of the system, the solar water heater has been designed in a conical shape, which removes the need to change its orientation toward the sun to receive the maximum sun radiation during the day. In this system, the heating of water has been obtained using the spiral pipe flow without the use of the solar cells and mirrors in order to reduce the total cost. The storage water tank of this system is coupled with a conical solar collector. Based on the above design, the solar water heater has been fabricated and tested. In addition, an analytical modeling approach aiming to predict the flow rate within the conical integrated collector storage solar water heater (ICSSWH) and its efficiency, was developed. Modeling through a numerical simulation approach based on energy equations was performed. Considering the entire water amount and the total area of the cone, the amount of water (facing the sun per unit absorbing area in the two symmetrical parts of the system) is found to increase, which is expected to reach a maximum water temperature at a high performance. Our experimental findings show that the daily performance is around 32% and the highest water temperature of about 45°C is obtained in the system at 4 pm, according to seasons and weather conditions. An efficient and simple mathematical simulation approach for the new conical solar water heater is described then validates using experimental data