No abstract

Hybrid solar thermal power plants using the Brayton cycle are currently of great interest as they have proven to be technically feasible. This study evaluates mechanisms to reduce fuel consumption and increase the power generated, improving plant efficiency. An energy and exergy model for the hybrid solar plant is developed using an estimation model for the solar resource to determine the plant operation under specific environmental conditions. The effect of using different working fluids in the Brayton cycle, such as air, and helium in transcritical conditions and carbon dioxide in subcritical and supercritical conditions, is evaluated. Additionally, the plant's exergy destruction and exergy efficiency are evaluated. In those, it can be highlighted that the helium cycle in the same operating conditions compared to other working fluids can increase the power by 160%, increasing fuel consumption by more than 390%.

In the research the temperature acquisition was carried out inside and outside the wall an intermittent furnace and the evaluation of the energy loss on the wall during baking process, the first phase begins with the design, programming and implementation of an virtual instrument for data temperature acquisition and generation of temperatures profiles then, heat loss due to conduction on the furnace wall was determined considering one-dimensional heat flow, in radial direction and in a transitory state. The virtual instrument was programmed every 5 minutes and 1596 data were recorded, the input heat supplied to the furnace was 49.2x106 KJ and the energy losses due to the furnace wall were 5.2x106 KJ indicating the 10.57 percent of the supplied energy. Results of research have made it possible to establish trends in the temperature distribution, as well as identify thermal energy entering and leaving the furnace to propose improvements in performance of the furnace that increase its energy efficiency, reduce fuel consumption and gas emissions to the environment avoiding acute respiratory diseases.

A thermodynamic model is presented for evaluation of a solar hybrid gas-turbine power plant. The model uses variable ambient temperature and estimates direct solar radiation at different day times. The plant is evaluated in Barranquilla, Colombia, with a solar concentration system and a combustion chamber that burns natural gas. The hybrid system enables to maintain almost constant the power output throughout day. The model allows optimizing the different plant parameters and evaluating maximum performance point. This work presents pressure ratio ranges where the maximum values of overall efficiency, power output, thermal engine efficiency and fuel conversion rate are found. The study is based on the environmental conditions of Barranquilla, Colombia. The results obtained shows that optimum pressure ratio range for power output and overall efficiency is between 6.4 and 8.3, when direct solar radiation its maximum at noon. This thermodynamic analysis is necessary to design new generations of solar thermal power plants.

The Colombian electricity sector is mainly composed of hydropower plants covering up to 70% of the total power generation. Several alternatives had been evaluated to complement Colombian’s energy mix, including solar PV and wind energy plants; however, there is no consensus about the appropriate solution in terms of the available resource, energy demand, and energy mix complementing. This work presents the performance evaluation of a hybrid thermosolar power plant at a city on the Caribbean Colombian coast, considering local environmental conditions such as ambient temperature and solar resource availability to attain the factor that constrain its optimal operating conditions. The overall energy and exergy plant efficiency is analyzed, considering an arbitrary number of stages. For instance, comparing a single-stage plant running with air with a two compression stages with inter-cooling and two expansion stages with reheating, the results indicate a 30 % higher exergy efficiency, and overall energy efficiency about 32 % larger and a fuel conversion rate around 18 % larger.