Gas turbine power plants have been widely studied, and as a result the negative effects on their output power and thermal efficiency have been known when operating in atmospheric conditions exceeding ISO conditions. For this reason, different technologies and methodologies have been implemented, aiming to increase the output power and improve the thermal efficiency. Unfortunately, the lack of operational parameters for this system limited its characterization and implementation of strategies to improve its performance. Advanced exergetic and exergoeconomic analyses have been applied to improve energy and economic performance in steam injection gas turbine (STIG) cycle power plants with air cooling with a compression refrigeration machine. Results shows that the main sources of irreversibilities and higher costs are in the Combustion Chamber (CC), Heat Recovery Steam Generator (HRSG) and Gas Turbine (GT). From these components, the components of the HRSG and GT have the greatest potential for improvement, and this can be achieved by improving the overall configuration of the system, due to the fact that the destruction of exogenous exergy is in more significant measure avoidable. While the higher costs of investment can be reduced in the Combustion Chamber and Gas Turbine.

Within this study, single-cable propagation facilitated by PV strings’ wiring characteristics is considered for an adapted design of PLC electronics. We propose to close the communications signal path, resulting in a ring topology where a resonance condition could be implemented. A PLC topology using the resulting circular closed-loop path of a PV series string as its physical communication support is designed and leveraged for practical use. When the path length or the number of transceivers is changed, the resonance properties that come with the circular path as the physical support are affected but are shown to be preserved with the application of automatic adjustable tuning. This automatic tuning guarantees that the resonance improves propagation parameters and reverts the system to its optimal values at the chosen carrier frequency.

Conventional exergy analysis identifies the more inefficient components; however, this doesn’t regard interaction between components, neither real improvement potential to each component of the system, this information is providing for the advanced exergy analysis. In this paper was developed an advanced exergy analysis to determine the optimal range of the compressor inlet air temperature, to compensate the power loss in a power plant with Stig cycle and an air cooling system. This plant without cooling system at ISO conditions produce 52 MW, while in local conditions (32 °C, 80%RH) its productions decreases to 44.3MW. The results showed that for every degree centigrade that the air temperature decreases at inlet compressor the power output increases in 0.17 MW and total destroyed exergy increases 0.23 MW. It was determined that for the optimal range of compressor inlet air temperature is between 10 and 12°C; at this range were obtained the highest power output values, and the values of the avoidable and endogenous exergy destroyed are diminished in 0.28 MW and 0.20 MW respectively compared to those given in local operating conditions.

No abstract

Coastal lagoons are one of the most threatened ecosystems in the world, because of population growth, habitat destruction, pollution, wastewater, overexploitation and invasive species which are the main causes of their degradation. The objective of this paper was to evaluate the water quality behavior in a stressed coastal lagoon in Cartagena, Colombian Caribbean. Environmental data was analyzed using hypothesis testing, confidence intervals, and also Principal components analysis (PCA). The study was focused on water parameters such as dissolved oxygen (DO), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), salinity, pH, total dissolved solids, total coliforms (TC), Fecal coliforms (FC), ammonium (NH4+) and total phosphorus (TP). The analysis was conducted in line with the Colombian national water standard. Results showed that BOD5, COD, phosphorus, and coliforms are out of the limits for these variables in Colombia and are reaching levels that may be a threat to human health. Principal components analysis detected five components that explained 79.4% of the variance of data and showed that anthropogenic and temporal factors might be affecting the variation of the parameters.