Thermal Energy Replacement Potential in a Slaughter Plant From Rumen Pellets

In this work, steam generation was studied using natural gas or rumen as energy sources in a slaughter plant that sacrifices 7500 cattle per month, with consumption 0.5749 kg/s of saturated steam at 624 kPa. For a slaughtered cow, 10.5 kg of rumen can be obtained after being dried outdoors; for its final disposal, the slaughter plant bears the costs of USD 7.2 per ton of rumen. In the study, exergy and exergoeconomic performances were compared by generating steam with a natural gas boiler with the steam generation with a rumen boiler. From this, combustion analysis, energy efficiency, exergy destruction, exergy efficiency, exergy destruction costs, and generating 1 kg of steam from the two boilers were evaluated. The study results showed that the generation of steam with rumen is less efficient than with natural gas since it presents the exergy destruction of 1175.9 kW and exergy efficiency of 26.83%. While the generation of steam with rumen boiler was obtained, with exergy destruction of 1419.9 kW and exergy efficiency of 23.29%. Exergy destruction cost and the cost of generating 1 kg of steam using rumen were $/h 7821 and 0.0073$/kg, respectively. Although the generation of steam with natural gas present the exergy destruction cost of 26285 $/h and the cost of generating steam of 0.021$/kg, this indicators are higher using natural gas as a fuel that with rumen pellets

Indium And Gallium P-type Doping Of Hydrogenated Amorphous Germanium Thin Films

Hydrogenated amorphous germanium films have been p-type doped with indium and gallium. The room-temperature dark dc conductivity of the films has been found to change by several orders of magnitude within the studied dopant atomic concentration range (∼3×10 -5 to ∼1×10 -2). The conductivity change from n to p type for the more heavily doped materials indicates effective p-type doping. The hydrogen content and the optical gap of the doped films, on the other hand, remain essentially unchanged with respect to the undoped material. For the most doped samples, signs of metallic segregation have been detected in the case of gallium doping. Metallic segregation is not apparent for indium-doped samples.64243273327

Determination of the optimal range of the compressor inlet air temperature in a power plant with stig cycle through of advanced exergetic analysis

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. Copyright © 2019 ASME

EXERGOECONOMIC ANALYSIS in A CEMENT PRODUCTION PLANT

A dry-type Cement Production Plan of 151 Tons per hour was taken as a case of study to implement an exergoeconomic analysis. In this paper, the exergy destruction and the investment costs of the system's units were calculated to obtain accurate information about the performance of the process, from the exergoeconomic factor and the relative difference cost. Conventional exergoeconomic analysis showed that the total cost of exergy destruction is 4206537 USD/h. The Calciner and the Rotary Kiln cause 62% of the total cost of the exergy destruction. The lowest values of the exergoeconomic factor were calculated for Calciner (0.01%), Clinker Cooler (0.01%), Rotary Kiln (0.02%), and Raw Mill (0.04%). The significant difference in relative cost was calculated for Calciner (42%) and Rotary Kiln (54.21%). The above implies that this equipment should be considered for an investment that allows the decrease of the exergy destruction cost and the increase of the exergetic efficiency. © 2020 ASME

EFFECT of the ENVIRONMENTAL CONDITIONS of TROPICAL CLIMATES on the PERFORMANCE PARAMETERS of A GAS TURBINE POWER GENERATION PLANT Fajardo J. ; Barreto D. ; Castro T. ;

It is known that high temperatures adversely affect the performance of gas turbines, but the effect of the combination of atmospheric conditions (temperature and relative humidity -RH- ) on the operation of this type of system is unknown. In this work the effects of atmospheric conditions on the energy and exergy indicators of a power plant with gas turbine were studied. The indicators studied were the mass flow, the specific work consumed by the compressor, specific work produced by the turbine, the combustion gas temperature, the NO concentration, the net output power, the thermal efficiency, the heat rate, the specific consumption of fuel, the destruction of exergy and exergy efficiency. Among the results, it is noted that for each degree celsius that reduces the temperature of the air at the compressor inlet at constant relative humidity on average, the mass flow of dry air increases by 0.27 kg/s, the specific work consumed by the compressors decreases by 0.45%, the output power increases by 1.17% and the thermal efficiency increases by 0.8%, the exergy destruction increases by 0.72% and the exergy efficiency increases by 0.81%. In addition, humidity changes relative to high temperatures are detected more significantly than at low temperatures. The power plant studied is installed in Cartagena, Colombia and since it is not operating in the design environmental conditions (15 C and 60% relative humidity) it experiences a loss of output power of 6140 kW and a drop in thermal efficiency of 5.12 %. These results allow considering the implementation of air cooling technologies at the compressor inlet to compensate for the loss of power at atmospheric air conditions. © 2020 ASME

Hacia el análisis de oportunidades energéticas con fuentes alternativas en el departamento de Nariño

Los proyectos sostenibles con fuentes no convencionales de energía han probado ser una solución técnica y económicamente factible para la energización de las regiones apartadas. Partiendo de la situación generalizada del país y, en particular de Nariño, el planteamiento de proyectos de investigación que analicen los recursos locales permitirá contribuir al desarrollo de un modelo que tenga en cuenta la inclusión de fuentes renovables y su gestión por medio de tecnologías de redes inteligentes que faciliten programas de eficiencia energética y uso racional de la energía. En este sentido, el proyecto Análisis de Oportunidades Energéticas con Fuentes Alternativas en el departamento de Nariño (ALTERNAR) plantea la caracterización de los recursos a nivel local y la investigación en sistemas completos de suministro de energía en zonas no interconectadas para incentivar el desarrollo económico y social de estas regiones rurales del departamento

The Spitzer Atlas of Stellar Spectra

We present the Spitzer Atlas of Stellar Spectra (SASS), which includes 159 stellar spectra (5 to 32 mic; R~100) taken with the Infrared Spectrograph on the Spitzer Space Telescope. This Atlas gathers representative spectra of a broad section of the Hertzsprung-Russell diagram, intended to serve as a general stellar spectral reference in the mid-infrared. It includes stars from all luminosity classes, as well as Wolf-Rayet (WR) objects. Furthermore, it includes some objects of intrinsic interest, like blue stragglers and certain pulsating variables. All the spectra have been uniformly reduced, and all are available online. For dwarfs and giants, the spectra of early-type objects are relatively featureless, dominated by Hydrogen lines around A spectral types. Besides these, the most noticeable photospheric features correspond to water vapor and silicon monoxide in late-type objects and methane and ammonia features at the latest spectral types. Most supergiant spectra in the Atlas present evidence of circumstellar gas. The sample includes five M supergiant spectra, which show strong dust excesses and in some cases PAH features. Sequences of WR stars present the well-known pattern of lines of HeI and HeII, as well as forbidden lines of ionized metals. The characteristic flat-top shape of the [Ne III] line is evident even at these low spectral resolutions. Several Luminous Blue Variables and other transition stars are present in the Atlas and show very diverse spectra, dominated by circumstellar gas and dust features. We show that the [8]-[24] Spitzer colors (IRAC and MIPS) are poor predictors of spectral type for most luminosity classes.Comment: Accepted by ApJS; Atlas contents available from: http://web.ipac.caltech.edu/staff/ardila/Atlas/index.html; http://irsa.ipac.caltech.edu/data/SPITZER/SASS/; 70 PDF pages, including figure

Efficiency Centered Maintenance of Preheat Train of a Crude Oil Distillation Unit

Nowadays, maintenance is based on the synergistic integration of operational reliability and timely maintenance, which guarantees the required availability and optimal cost. Operational reliability implies producing more, better performance, longer life, and availability. Timely maintenance involves the least time out of service, fewer maintenance costs, fewer operating costs, and less money. In this work, we study the preheating train of a crude distillation unit of a refinery, which processes 994 m3/h, which presents a formation of a foulinglayer inside it. Among the impacts of fouling is the reduction in the effectiveness of heat transfer, the increase in fuel consumption, the increase in CO2 emissions, the increase in maintenance costs, and the decrease in the profit margin of process. An appropriate cleaning program of the surface of the heat exchanger network is necessary to preserve its key performance parameters, preferably close to design values. This paper presents the maintenance method centered on energy efficiency, to plan the intervention of the preheating train equipment maintenance, which considers the economic energy improvement and the cost of the type of maintenance. The method requires the calculation of the fouling evolution from which the global heat transfer coefficient is obtained, and the heat flux is determined as a function of time. It was observed that, as time passes, the resistance provided by fouling increases and that the overall heat transfer coefficient decreases. The energy efficiency centered maintenance has an indicator of economic justification (factor J) that relates the economic-energy improvement achieved when performing maintenance, taking into account the economic effort invested. Depending on the cost of the type of maintenance to be performed, a threshold should be chosen, from which the maintenance activity is justified. The effectiveness values of the heat exchanger (e) and the J indicator are used to form a criticality matrix, which allows prioritizing maintenance activities in each equipment. The planning of the implementation dates of the maintenance of each heat exchanger, from the maintenance method centered on energy efficiency applied to the crude distillation unit's, preheat train, constitutes a contribution in this specific field. The conceptual design of the maintenance method centered on energy efficiency presented in this work is feasible for other heat transfer equipment used in oil refineries and industry in general. The procedure developed uses real operation values, and with its implementation, a saving of 150000 US dollars was achieved. © 2020 ASME

Configuración Software de la directividad de arrays lineales

A line array can be defined as a column of loudspeakers that is designed so that these work together to achieve a higher directivity. This paper presents an application that enables a user to rotate the wavefront of uniform line arrays. Theoretical background and details of the implementation are provided. The validity of the application is tested with measurements of the directivity that are also compared with simulations.Este trabajo ha sido financiado Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech y el grupo de investigación Aplicación de las Tecnologías de la Información y Comunicaciones (PAI TIC-208)