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Arriaga M.,Electric Research Institute of Mexico
Renewable Energy | Year: 2010

This paper presents the pico-hydro development status in Lao PDR and introduces the Pump as Turbine (PAT) concept as an alternative for isolated communities (40-500 people). The intention is to provide a long-term reproducible system for communities where pico-hydro propeller turbines are insufficient and proper turbines are expensive. This approach presents a high quality and cost-effective solution for rural electrification which can be installed, commissioned, and maintained by local staff and villagers. Furthermore, a 2 kWel PAT-scheme is proposed for a community in the Xiagnabouli province and considers power generation alternatives, sizing, asynchronous motor simulation, civil works, cost estimation, and social aspects. © 2009.

Hernandez-Escobedo Q.,University of Veracruz | Saldana-Flores R.,Electric Research Institute of Mexico | Rodriguez-Garcia E.R.,University of Veracruz | Manzano-Agugliaro F.,University of Almeria
Renewable and Sustainable Energy Reviews | Year: 2014

Mexico has installed less wind power compared to the other North American countries. Renewable energy sources only account for 3% of the energy mix in Mexico. The U.S. states bordering Mexico, namely Texas, New Mexico, Arizona, and California, have good wind power resources. Among them, Texas has the highest installed wind power capacity of 10.34 GW. The wind resources in these bordering states indicate that the wind energy resource in Northern Mexico must be assessed; thus, the spatial and temporal information about the wind energy resource was studied. The daily pattern of the wind speed, one per state studied, was obtained. The wind speed was found to exhibit a pattern; it increases from 4 pm until 6 am the following day. The main conclusions are that the state of Tamaulipas has the highest Wind Power Density (WPD) of 1000 W/m2 during September and October, but the north of Nuevo Leon has, in a large part of its territory, an annual WPD greater than 103 W/m 2; each state has 1700 useful hours of wind speed above 3 m/s. Northern Mexico has some zones with excellent wind speed as well; the states of Chihuahua, Coahuila, Nuevo Leon and Tamaulipas have a wind speed of over 4.51 m/s across nearly their entire territories. Because Mexico in recent years has been starting to exploit renewable energy sources, the government has mandated energy reform, which improves the conditions for investment in wind energy in Mexico. © 2014 Elsevier Ltd.

Aviles J.,Instituto Mexicano Of Tecnologia Del Agua | Eduardo Perez-Rocha L.,Electric Research Institute of Mexico
Soil Dynamics and Earthquake Engineering | Year: 2011

This paper investigates the applicability of global ductility in the conventional design procedure of structure-foundation systems under earthquake excitation. For a bilinear elastoplastic model, an equivalent ductility factor for the combined structure and foundation is derived, which can be used in conjunction with the enlarged period and increased damping due to soil-structure interaction (SSI) to determine the design strength. A geometric transformation rule for predicting the ductility demand developed in the structure alone from that experienced by the interacting system is also derived, without the need of computing the rigid-body motion of the foundation. To validate this practical approach for assessing both inelastic strengths as well as ductility demands, a number of numerical results for different system parameters and earthquake excitations are provided. The effects of principal parameters involved are also examined. © 2011 Elsevier Ltd.

Martinez-Ortiz J.,National Autonomous University of Mexico | Flores R.,Electric Research Institute of Mexico | Vazquez-Duhalt R.,National Autonomous University of Mexico
Biosensors and Bioelectronics | Year: 2011

In order to improve the direct electron transfer in enzymatic biofuel cells, a rational design of a laccase electrode is presented. Graphite electrodes were functionalized with 4-[2-aminoethyl] benzoic acid hydrochloride (AEBA). The benzoic acid moiety of AEBA interacts with the laccase T1 site as ligand with an association constant (KA) of 6.6×10-6M. The rational of this work was to orientate the covalent coupling of laccase molecule with the electrode surface through the T1 site and thus induce the direct electron transfer between the T1 site and the graphite electrode surface. Direct electron transfer of laccase was successfully achieved, and the semi-enzymatic fuel cell Zn-AEBA laccase showed a current density of 2977μAcm-2 and a power density of 1190μWcm-2 at 0.41V. The molecular oriented laccase cathode showed 37% higher power density and 43% higher current density than randomly bound laccase cathode. Chronoaperometric measurements of the Zn-AEBA fuel cell showed functionality on 6h. Thus, the orientation of the enzyme molecules improves the electron transfer and optimizes enzyme-based fuel cells efficiency. © 2010 Elsevier B.V.

Gomes C.,University Putra Malaysia | Diego A.G.,Electric Research Institute of Mexico
Safety Science | Year: 2011

This paper provides comprehensive analysis on the lightning protection scenarios in 48 communication and broadcasting towers situated in similar isokeraunic contours in Sri Lanka at 79°-81° East and 5°-10° North. The investigation has been conducted to study the hazardous environment created on the tower and in the neighbourhood in the event of a lightning strike to the tower. The results show that a direct strike to an antenna structure in a metallic tower is rare irrespective of the presence of an air-termination or a down conductor. However, side flashing or arcing to antenna structures is highly possible once the air-termination and/or down conductor is installed and attempts are made to insulate the system from the tower. The outcome also shows that equipotential bonding of the grounding system, a distributed grounding network including a ring conductor and a suitable system of surge protective devices play a much vital role in lightning protection of equipment and safety of people compared to the effects of simply achieving a low grounding resistance. However, in the absence of such integrated, distributed and equipotentialized grounding system, a high value of ground resistance will sharply increase the possibility of accidents and damage. Considering the observations of the investigations into account we have designed a concrete embedded grounding system for tower sites at problematic locations. Finally, the scenarios for safety management at telecommunication tower sites have been discussed. © 2011 Elsevier Ltd.

Verma M.P.,Electric Research Institute of Mexico
Revista Mexicana de Ciencias Geologicas | Year: 2013

A computer program, GeoSteamNet, for the numerical simulation of steam transport in geothermal pipeline networks is written in Visual Studio .NET. The program considers (a) internally consistent thermodynamic properties of water, and (b) a numerical algorithm based on the principles of conservation of mass, linear momentum (Newton's second law), and energy (the first and second laws of thermodynamics). Instability in the algorithm is observed as a consequence of ideal gas behavior of steam at low pressure, which is resolved by setting the lower limit of pressure to 2.0×105 Pa. An ActiveX control, SteamTablesGrid, is used to calculate the thermodynamic properties of water. A study of the interrelationship among thermodynamic state variables like temperature, pressure, volume, internal energy, etc. indicates the internal consistency in the thermodynamic properties of steam only. The application of GeoSteamNet is demonstrated in the management and optimization of steam flow in a hypothetical geothermal power plant with two wells and one production unit. GeoSteamNet calculates all the parameters like fluid velocity, different types of energies such as heat loss, mechanical (kinetic and potential) energy, thermal energy, frictional energy, and total energy. Thus, the mass, linear momentum and energy balances at each nodal point in the pipeline network are used to validate the algorithm. Additionally, the computer program can also be used efficiently in the design and construction of geothermal pipeline network.

The results of International Atomic Energy Agency (IAEA) inter-laboratory comparison program reported in the literature during 1992 and 2004 were analyzed to estimate analytical uncertainty in the geochemical analysis of geothermal waters. Statistical data treatments for the detection and elimination of outliers and extremums were performed using five methods: (i) data visualization (or raw data statistics); (ii) mean (x) and standard deviation (s) calculation after eliminating outliers with x ± 2s; (iii) median and median absolute difference (MAD); (iv) Huber method; and (v) single-outlier type multiple test method involving Dixon, Grubbs, skewness and kurtosis tests at 99% confidence level. The results are reported in scientific notation with one signifcant digit of uncertainty. A comparative study of all the five statistical data treatment methods suggests that the fifth method provides better results for the statistical analysis of experimental measurements. A preliminary evaluation for the analytical accuracy of geochemical analysis of geothermal waters, prepared by dissolving 4.585 g CaCl2 (98.2%), 16.5 g NaCl (99.9%), 3.58 g MgCl2 (99.0%), 0.74 g Na2SO4 (99.0%) and 0.95 g KCl (99.5%) in 1 liter of solution, is presented. The analysis of Na+ and K+ are reasonably accurate, while Mg2+ and SO4 2- have high inaccuracy. The accuracy of Ca2+ and Cl- analyses is in-between. A systematic analysis of the results suggests that the present inaccuracy in the measurements of Mg2+, Ca2+, SO4 2- and Cl- are probably associated with the sample preparation. The relations between the coefficient of variation (i.e. % analytical uncertainty) and concentration of each element are derived, which are used for the propagation of uncertainty in the geochemical calculations of geothermal systems. The uncertainty propagation procedure is illustrated in the calculation of Los Azufres geothermal reservoir temperature and vapor fraction. The uncertainty in the estimated temperature is ±20 K, which means that the changes in the geothermal reservoir fluid characteristics during its exploitation are generally within the uncertainty.

The quartz solubility geothermometry to calculate geothermal reservoir temperature and vapor fraction with multivariate analytical uncertainty propagation is programmed as two classes, SiO2TD and QrtzGeotherm in Visual Basic in Visual Studio 2010 (VB.NET). The class, SiO2TD calculates the total discharge concentration, SiO2TD and its uncertainty, SiO2TDErr from the analytical concentration of silica, SiO2msd and uncertainty, SiO2msdErr of separated water, sampled after N-separations of vapor and liquid. The class, QrtzGeotherm uses the following properties as input parameters: (i) HRes-reservoir enthalpy (kJ/kg), (ii) HResErr-uncertainty in the reservoir enthalpy (kJ/kg), (iii) SiO2TD-total discharge silica concentration (ppm), (iv) SiO2TDErr-uncertainty in the total discharge silica concentration (ppm) (v) GeoEq-number of quartz solubility regression equation, (vi) TempGuess-a guess value of the reservoir temperature (°C). The properties corresponding to the output parameters are (i) TempRes-reservoir temperature (K), (ii) TempResErr-uncertainty in the reservoir temperature (K), (iii) VaporRes-reservoir vapor fraction and (iv) VaporResErr-uncertainty in the reservoir vapor fraction. Similarly, it has a method, SiO2Eqn(EqNo, Temp) to provide the silica solubility as function of temperature corresponding to the regression equation.Four quartz solubility equations along the liquid-vapor saturation curve: (i) a quadratic equation of 1/T and pressure, (ii) a linear equation relating log SiO 2 to the inverse of absolute temperature (T), (iii) a polynomial of T including logarithmic terms and (iv) temperature as a polynomial of SiO 2 including logarithmic terms are programmed. A demonstration program, QGeotherm is written VB.NET. Similarly, the applicability of classes SiO2TD and QrtzGeotherm in MS-Excel is illustrated considering Los Azufres geothermal field as an example. © 2012 Elsevier Ltd.

Verma M.P.,Electric Research Institute of Mexico | Mario Cesar Suarez A.,University of Morelia
Journal of Statistical Software | Year: 2014

The computer program DixonText.CriticalValues is written in VB.NET to extend the quadrature approach to calculate the critical values with accuracy up to 6 significant digits for Dixon's ratios. Its use in creating the critical values tables in Excel is illustrated.

Verma M.P.,Electric Research Institute of Mexico
Computers and Geosciences | Year: 2011

An ActiveX control, steam tables grid (StmTblGrd) to speed up the calculation of the thermodynamic properties of pure water is developed. First, it creates a grid (matrix) for a specified range of temperature (e.g. 400-600. K with 40 segments) and pressure (e.g. 100,000-20,000,000. Pa with 40 segments). Using the ActiveX component SteamTables, the values of selected properties of water for each element (nodal point) of the 41×41 matrix are calculated. The created grid can be saved in a file for its reuse. A linear interpolation within an individual phase, vapor or liquid is implemented to calculate the properties at a given value of temperature and pressure.A demonstration program to illustrate the functionality of StmTblGrd is written in Visual Basic 6.0. Similarly, a methodology is presented to explain the use of StmTblGrd in MS-Excel 2007. In an Excel worksheet, the enthalpy of 1000 random datasets for temperature and pressure is calculated using StmTblGrd and SteamTables. The uncertainty in the enthalpy calculated with StmTblGrd is within ±0.03%. The calculations were performed on a personal computer that has a "Pentium(R) 4 CPU 3.2. GHz, RAM 1.0. GB" processor and Windows XP. The total execution time for the calculation with StmTblGrd was 0.3. s, while it was 60.0. s for SteamTables. Thus, the ActiveX control approach is reliable, accurate and efficient for the numerical simulation of complex systems that demand the thermodynamic properties of water at several values of temperature and pressure like steam flow in a geothermal pipeline network. © 2010 Elsevier Ltd.

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