In this chapter, power consumption and electrical demand in buildings or housing due to the utilization of HVAC systems are shown to be intimately linked to construction materials. This work proposes a methodology of energy management intended to analyze and evaluate actions aimed at saving and efficient use of electric energy of HVAC systems applied to regions with hot and dry climates. The methodology consists of: (1) characterization of local climatology using the concept of degree-hours (DH). (2) Utilization of a Fourier-type mathematical model to calculate hourly temperature using only daily maximum and minimum temperatures as well as an empirical model to compute energy efficiency (EER) of air-cooled air conditioning units. (3) Thermal simulation applying a software developed by the authors based on ASHRAE's Transfer Functions methodology to calculate hourly cooling loads, the adequate sizing of air conditioning equipment and the rate of heat extraction. (4) System analysis, identification of improvement actions, evaluation of viable alternatives of saving and efficient use of energy. The advantage of this proposal is its flexibility because it can be applied to any climatology and easily adaptable to the conditions of energy usage anywhere in the world.

Nueva metodología de diagnóstico de fallas en rodamientos en una máquina síncrona mediante el procesamiento de señales vibroacústicas empleando análisis de densidad de potencia

This research presents the modeling and prediction of the harmonic behavior of current in an electric power supply grid with the integration of photovoltaic power by inverters using artificial neural networks to determine if the use of the proposed neural network is capable of capturing the harmonic behavior of the photovoltaic energy integrated into the user's electrical grids. The methodology used was based on the use of recurrent artificial neural networks of the nonlinear autoregressive with external input type. Work data were obtained from experimental sources through the use of a test bench, measurement, acquisition, and monitoring equipment. The input–output parameters for the neural network were the current values in the inverter and the supply grid, respectively. The results showed that the neural network can capture the dynamics of the analyzed system. The generated model presented flexibility in data handling, allowing to represent and predict the behavior of the harmonic phenomenon. The obtained algorithm can be transferred to physical or virtual systems for the control or reduction of harmonic distortion.

An experimental survey was developed to determine optimal operational conditions when extracting tanning materials from milled divi-divi pods with a 10% (v/v) alcohol-water solution. The study included runs at both laboratory and pilot levels. The percentage of extracted tanning materials from samples was measured when varying the following variables: (1) temperature, (2) solvent to solute ratio, (3) extracting time, (4) type of solvent, (5) agitation, and (6) average particle size. The optimal values were as follows: 5 0 T , 120 cm3 of solvent: 1 g of divi-divi, 20 min, 10% (v/v) ethanol-water, agitation on, and 0.087 cm average particle size. The maximum yield of extracted tanning materials was 54% by weight (dry basis) when divi-divi pods up to 6 months old were used, but the tannic content in pods decreased by 15% and 32% after 12 and 42 months of storage respectively.

Reducing household energy consumption is one of the most important strategies used to decrease fossil fuel consumption and greenhouse gases emissions, and to encourage renewable energy utilization. Most energy conservation strategies in the domestic sector are aimed at preferential loans, i.e., purchasing renewable electricity or to improve the efficiency of home appliances, such as air conditioning and lighting. However, despite the relative economic successes of these technologies, they have not had expected impacts in regard to energy consumption. In this work, the authors analyzed the consumption patterns of two equivalent households—one was adapted with improved thermal insulation and a 1.2 kW photovoltaic system to reduce consumption from the electrical grid. The results show that dwellings where no improvements were made registered lower electric energy consumption, due the fact that users were aware that no strategy had been implemented, and its consumption; hence, electricity payments depended solely on one’s attention over the electronic device operations. On the other hand, energy conservation strategies in households promotes confident and relaxed attitudes toward the use of energy, leading to lower energy billings, but a higher gross energy consumption.