Thermo-economic and environmental optimization using PSO of solar organic Rankine cycle with flat plate solar collector.

The use of solar energy is considered a potential strategy for the production of electrical energy through thermal heat sources. This article portrays a study framed to be energetic, economic, and environmental fields. This study was carried out in two thermal configurations: the Regenerative Rankine Cycle (RORC) and the Simple Organic Rankine Cycle (SORC), which use solar energy to supply electrical power to a building. The thermodynamic and economic models were proposed for each subsystem of the thermal process, allowing hourly simulations to know the economic indicators such as the payback period (PBP), the levelized cost of energy (LCOE), the specific investment cost (SIC), and the initial investment cost ( C I n v ). The effect of operational variables such as the pressure ratio (rp), the evaporator pinch point temperature (Ap), the condensation pinch point temperature (Tcond), and the solar collector area (Ac) on the Relative Annual Benefit (RAB) were studied. Finally, the Particle Swarm Optimization (PSO) algorithm was implemented to optimize the economic indicators and the environmental impact of the thermal configurations. Results showed that the RORC configuration presented a better performance in terms of generation, purchase, and hourly sale of energy. However, in terms of RAB, the SORC (39,833 USD/year) showed better results in contrast to the RORC (39,604 USD/year) for an evaporator pinch point temperature of 35 °C. Finally, the application of the PSO optimization algorithm allowed the reduction of the LCOE (11.64%), SIC (11.67%), and PBP (11.81%) thermo-economic indicators from the base condition for the SORC, and the reductions obtained in the RORC were LCOE (18.11%), SIC (10.67%), and PBP (11.11%). However, the decrease in environmental Impact for both systems was less than 1% as a consequence of the high contribution of thermal oil in the construction phase of the system.

Energy, exergy, and environmental assessment of a small-scale solar organic Rankine cycle using different organic fluids.

This article presents an energetic, exergetic, and environmental (3E) analysis of a solar powered simple Rankine Organic Cycle (ORC). The ORC is simulated using three organic working fluids, such as Toluene, Cyclohexane, and Acetone, meanwhile the solar system uses thermal oil Therminol 75. The present study shows the performance of this coupled system using historical solar annual radiation data from four of the highest solar potential locations in Colombia. Data used correspond to data for the cities Rancho Grande, Puerto Bolivar, Manaure, and Nazareth. Simulations were performed using commercial programs as MATLAB® and REFPROP 9.0. Energy production, the energy and exergetic efficiencies of the system, the exergy destruction was calculated based on the input of the global solar radiation. Effects generated by each working fluid in the solar powered ORC system was determined. It was stablished that the heat obtained in the solar collector in combination with a storage tank is incorporated during non-radiation hours guarantees the thermal stability of the working fluid in the ORC. The best performance corresponds to the Rancho Grande city, being the Toluene the corresponding working fluid with the highest energy (14.6%) and exergetic (7.37%) efficiencies, as well as the maximum power generation (5.50 kW) for October month, meanwhile, the highest exergy destruction values correspond in April. A sensitivity analysis of the individual elements of the system was performed. This study revealed the preference of a lower evaporator pinch point temperature, higher turbine thermal efficiency, pump thermal efficiency, and pressure ratio to obtain better energy and exergy efficiency of the solar powered ORC system. Additionally, the potential environmental impact of the system was evaluated through a Life Cycle Analysis, obtaining for the solar system solar collector has the highest environmental impact with 78557850 mPts. Meanwhile for the ORC, the turbine registers the most significant environmental impact with 295516 mPts (7.34%), when Toluene is used as a working fluid and copper as a construction material in the location of Rancho Grande. In conclusion, the potentiality of planning the operation of solar powered ORC was successfully evaluated for four specific locations in Colombia.

Development of a new educational package based on e-learning to study engineering thermodynamics process: combustion, energy and entropy analysis.

This paper presents a new educational package based on e-learning called TermolabUA integrated by three programs, which are VOLCONTROL focused on the analysis of steady-state flow devices, CarnotCycle aimed to analyze reversible and irreversible processes, and CombustionUA to study combustion processes. The educational package was designed for both, to promote significant learning on some thermodynamic topics in undergraduate students, and to help the student to reach the cognitive competencies of interpreting, arguing and proposing, and interacting with the different graphical user interfaces to solve relevant cases studies. Also, the teaching-learning activity helps them to understand the influence of a specific variable on the energy and entropy behavior of the selected systems, which is traditionally studied manually in a classroom. The results of the t-Student tests showed that the average grades obtained by the students in the problems using the software were higher than the average grade without using the software. The estimate for the average grade difference was 0.56 with a P-value = 3.31E-13 for Problem 1 and 0.631 with a P-value = 3.31E-13 for Problem 2 in the Workshop- VOLCONTROL. Similar results were obtained for the problems reported in the CarnotCycle and CombustionUA Workshop with an estimate for average grade differences and P-values lower than 0.79 and 0.05, respectively. It means that the new software package significantly improved the learning skills of the students.

A comparative energy and exergy optimization of a supercritical-CO2 Brayton cycle and Organic Rankine Cycle combined system using swarm intelligence algorithms.

This article presents a multivariable optimization of the energy and exergetic performance of a power generation system, which is integrated by a supercritical Brayton Cycle using carbon dioxide, and a Simple Organic Rankine Cycle (SORC) using toluene, with reheater ( S - C O 2 R H - S O R C ), and without reheater ( S - C O 2 N R H - S O R C ) using the PSO algorithm. A thermodynamic model of the integrated system was developed from the application of mass, energy and exergy balances to each component, which allowed the calculation of the exergy destroyed a fraction of each equipment, the power generated, the thermal and exergetic efficiency of the system. In addition, through a sensitivity analysis, the effect of the main operational and design variables on thermal efficiency and total exergy destroyed was studied, which were the objective functions selected in the proposed optimization. The results show that the greatest exergy destruction occurs at the thermal source, with a value of 97 kW for the system without Reheater (NRH), but this is reduced by 92.28% for the system with Reheater (RH). In addition, by optimizing the integrated cycle for a particle number of 25, the maximum thermal efficiency of 55.53% (NRH) was achieved, and 56.95% in the RH system. Likewise, for a particle number of 15 and 20 in the PSO algorithm, exergy destruction was minimized to 60.72 kW (NRH) and 112.06 kW (RH), respectively. Comparative analyses of some swarm intelligence optimization algorithms were conducted for the integrated S-CO2-SORC system, evaluating performance indicators, where the PSO optimization algorithm was favorable in the analyses, guaranteeing that it is the ideal algorithm to solve this case study.

Data set on wind speed, wind direction and wind probability distributions in Puerto Bolivar - Colombia.

This paper presents wind speed and direction data measured with a weather station located in Puerto Bolivar, department of La Guajira, situated in the extreme north of Colombia, whose geographic coordinates are 12°11'N 71°55'W. A wind speed and direction sensor, a barometric pressure sensor, and a temperature sensor were used to obtain the presented data. These data were taken at the height of 10 m, which is the highest point of the weather station. The data taken by the meteorological station correspond to a period of 20 years (1993-2013), with hourly frequency. For the missing data, a mathematical model to estimate the Julian averages was developed, allowing to calculate the frequency histograms and four types of probability distributions for these data. Also, the representative wind roses were generated, taking into account the averages in each of the 12 months of the year.