scholarly journals Thermal potential of a geothermal earth-to-air heat exchanger in six climatic conditions of México

2020 ◽  
Vol 21 (3) ◽  
pp. 308
Author(s):  
M. Rodríguez-Vázquez ◽  
J. Xamán ◽  
Y. Chávez ◽  
I. Hernández-Pérez ◽  
E. Simá

In this paper, the thermal and ventilation potential of a geothermal Earth-to-Air Heat exchanger (EAHE) is studied for six weather in Mexico. The cities for the study and their climate were Villahermosa (hot-humid), Merida (hot-sub humid), Monterrey (dry), Juarez City (very dry), Zacualtipan-Hidalgo (warm-humid) and Mexico City (warm-sub-humid). The thermal behavior of the EAHE was modeled numerically for the corresponding warmest and coldest days of the year for each city and three values of Reynolds number. The 24 hrs simulations were carried out with an in-house code using data every 10 minutes. To get the results, 5,184 computational runs were necessary. The results showed that the EAHE has poor ventilation potential for climates with high levels of humidity such as Villahermosa, while for cities with low levels of humidity such as Chihuahua, the ventilation potential increases significantly, the rest of the cities fall in between. As for its application in Mexico, the results show that the EAHE is highly recommended for dry climates such as at the north of the country and not recommended for humid climates such as at the south and south-east of the country.

2017 ◽  
Vol 17 (12) ◽  
pp. 2289-2300 ◽  
Author(s):  
Manuel Mora García ◽  
Jesús Riesco Martín ◽  
José Miguel Sánchez Llorente ◽  
Luis Rivas Soriano ◽  
Fernando de Pablo Dávila

Abstract. Intense orographic precipitation associated with the Central Range was analysed using data of maximum accumulated precipitation in 24 h, occurring between 1958 and 2010. The 18 selected episodes were associated with a southwesterly tropospheric flow, a low-level jet, and high moisture flux at low levels. The observed moisture flux was higher than 100 (m g(s kg)−1) and the dry and wet Froude numbers were greater than 1. The selected area to study this synoptic situation was Gredos, broad and high range, which is located in the eastern part of the Central Range and generates a leeward orographic shadow. The effect of the Central Range on the spatial distribution of precipitation on the Iberian Peninsula plateau results in a sharp increase in precipitation in the south of the Central Range, followed by a decrease to the north of this range.


2017 ◽  
Author(s):  
Manuel Mora García ◽  
Jesus Riesco Martín ◽  
José Miguel Sánchez Llorente ◽  
Luís Rivas Soriano ◽  
Fernando de Pablo Dávila

Abstract. Intense orographic precipitation associated with the Central range was analysed using data from 19 episodes, with the highest average values for the study area, of precipitation accumulated within 24 h, occurring between years 1958 to 2010. All events were associated with a south-westerly tropospheric flow, a low level jet, and high moisture flux at low levels. The observed moisture flux was higher than 100 m g (s kg)−1 and the dry and wet Froude numbers were greater than 1. The selected area to study this synoptic situation was Gredos, broad and high range, which is located in the eastern part of the Central mountain range and generates leeward orographic shadow. The effect of the Central range on the spatial distribution of precipitation on the Iberian Peninsula plateau results in a sharp increase in precipitation in the south of the Central mountain range, followed by a decrease to the north of this range.


2018 ◽  
Vol 7 (3.11) ◽  
pp. 172
Author(s):  
Ricardo Sánchez B ◽  
Sabarinah S. Ahmad ◽  
Leonardo B. Zeevaert ◽  
Arturo Valeriano F

The study aims to understand the thermal performance behavior of a double skin envelope system in a test cell.  A rooftop observation deck and experimentation laboratory is installed at the “J” Building of the Postgraduate Unit, National Autonomous University of Mexico campus (19°18’33.59”N, 99°11’5.73”O).  This platform consists of two full-scale testing modules. Each cubic module measures 3m x 3m x 3m.  All of its facades have several layers of insulation.  This platform was designed to test materials and construction systems under the Mexico City microclimate.  It is possible to measure thermal, lighting, acoustic and indoor air quality variables. Mexico City building codes indicate that the minimum span to be used in a room must be at least 17.5% of the area of the room.  Using the Experimentation Façade, which allows us to observe all available orientations; we place a window with these characteristics and measure its thermal behavior in each of the orientations.  The results obtained allowed us to identify that the window when observing the North or South orientations does not greatly increase the internal temperature of the Module.  On the other hand, when the window observes the orientations East and West, the internal temperature increase, establishes conditions of inhabitability inside the Module, recording temperatures of above 50°C.  


Author(s):  
Ewin Karman Nduru ◽  
Efori Buulolo ◽  
Pristiwanto Pristiwanto

Universities or institutions that operate in North Sumatra are very many, therefore, of course, competition in accepting new students is very tight, universities or institutions do certain ways or steps to be able to compete with other campuses in gaining interest from community or high school students who will continue their studies to a higher level. STMIK BUDI DARMA Medan (College of Information and Computer Management), is the first computer high school in Medan which was established on March 1, 1996 and received approval from the government through the Minister of Education and Culture, on July 23, 1996 with operating license number 48 / D / O / 1996, in promoting the campus, the team usually formed a promotion team to various regions in the North Sumatra Region to provide information to the community. Students who have learned in this campus are quite a lot who come from various regions in North Sumatra, from this point the need to process data from students who are active in college to be processed using data mining to achieve a target, one method that can be used in data mining, namely the ¬K-Modes clustering (grouping) algorithm. This method is a grouping of student data that will be a help to campus students in promoting, using the K-Modes algorithm is expected to help and become a reference for marketing in determining the marketing strategy STMIK Budi Darma MedanKeywords: STMIK Budi Darma, Marketing Strategy, K-Modes Algorithm.


Author(s):  
V. Fedorov ◽  
E. Sleptsov ◽  
K. Plemyashov

A growth in the number of deer and an increase in their productivity are closely related to the solution of the complex problem of reproduction and rational use of deer females. Significant damage to reindeer husbandry is caused by the barrenness of northern domestic deer, the level of which has been quite high in recent years. So, in the Republic of Sakha, on 01.01.2020, the number of domesticated reindeer was 152,068, of which female deer and heifers — 71,818, offspring per 100 females — 59, business yield amounted to 52 fawns per 100 females. The causes of infertility are very diverse, as the natural and climatic conditions of the breeding zones have a significant influence on the reproductive function of reindeer. In Yakutia, the main population of northern domestic deer is bred in mountain taiga and tundra natural-climatic zones, so there are about 55 thousand deer in the mountain taiga zone and more than 65 thousand deer in the tundra zone. In this regard, the study of the peculiarities of the postpartum period course in domestic reindeer females, its morphophysiology, and behavioral reactions depending on the natural and climatic conditions of breeding is of great importance.


2019 ◽  
pp. 42-44
Author(s):  
I.V. GUSAROV ◽  
V.A. OSTAPENKO ◽  
T.V. NOVIKOVА

Впервые в мире создана популяция зубров на территории 60 градусов северной широты. В новых климатических условиях разведения и сохранения зубров определены и проанализированы факторы существования вида на севере Европейской части РФ. Выявлены признаки, динамика численности, которые являются составной частью системы, предназначенной для управления биоразнообразием. Интродукция, являясь процессом введения в экосистему нехарактерных для нее видов, может усиливать изменения биоценозов как положительно, так и отрицательно. Насколько быстро и успешно проходит процесс адаптации заселенного вида, и усматривается его влияние на окружающую среду зависит дальнейшее существование зубров и в целом биоразнообразия. В статье обсуждаются вопросы взаимоотношения зубров с другими видами копытных и хозяйственной деятельностью человека, а также дальнейшим использованием зубров в сельскохозяйственном производстве. Пластичность зубров, выявление изменений и их анализ при вселении видов в новые условия обитания необходимы не только для определения развития или деградации биоценозов и в целом экосистемы, но и прогноза социально-экономических последствий интродукции как одного из методов сохранения редких и исчезающих видов фауны.For the first time in the world, a bison population has been created in an area of 60 degrees north latitude. In the new climatic conditions of breeding and preservation of bison, the factors of the species existence in the north of the European part of the Russian Federation are identified and analyzed. The signs, dynamics of abundance, which are an integral part of the system designed to manage biodiversity are identified, since the preservation of biological diversity on the planet is one of the main problems of our time. Introduction, being the process of introducing non-typical species into an ecosystem, can enhance changes in biocenoses, both positively and negatively. The question posing sounds especially when it comes to such a large hoofed animal as the European bison. How quickly and successfully the process of adaptation of the universe takes place and its environmental impact is seen depends on the continued existence of bison and biodiversity in general. The article discusses the relationship of bison with other types of ungulates and human activities, as well as the further use of bison in agricultural production. How these issues will be resolved positively depends on the future of these animals. Thus, the plasticity of bison, the identification of changes and their analysis, with the introduction of species into new habitat conditions is necessary not only to determine the development or degradation of biocenoses and the ecosystem as a whole, but also to predict the socio-economic consequences due to the introduction as one of the methods of preserving rare and endangered species of fauna.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Alejandro Lome-Hurtado ◽  
Jacques Lartigue-Mendoza ◽  
Juan C. Trujillo

Abstract Background Globally, child mortality rate has remained high over the years, but the figure can be reduced through proper implementation of spatially-targeted public health policies. Due to its alarming rate in comparison to North American standards, child mortality is particularly a health concern in Mexico. Despite this fact, there remains a dearth of studies that address its spatio-temporal identification in the country. The aims of this study are i) to model the evolution of child mortality risk at the municipality level in Greater Mexico City, (ii) to identify municipalities with high, medium, and low risk over time, and (iii) using municipality trends, to ascertain potential high-risk municipalities. Methods In order to control for the space-time patterns of data, the study performs a Bayesian spatio-temporal analysis. This methodology permits the modelling of the geographical variation of child mortality risk across municipalities, within the studied time span. Results The analysis shows that most of the high-risk municipalities were in the east, along with a few in the north and west areas of Greater Mexico City. In some of them, it is possible to distinguish an increasing trend in child mortality risk. The outcomes highlight municipalities currently presenting a medium risk but liable to become high risk, given their trend, after the studied period. Finally, the likelihood of child mortality risk illustrates an overall decreasing tendency throughout the 7-year studied period. Conclusions The identification of high-risk municipalities and risk trends may provide a useful input for policymakers seeking to reduce the incidence of child mortality. The results provide evidence that supports the use of geographical targeting in policy interventions.


Geothermics ◽  
2020 ◽  
Vol 84 ◽  
pp. 101741 ◽  
Author(s):  
H.P. Díaz-Hernández ◽  
E.V. Macias-Melo ◽  
K.M. Aguilar-Castro ◽  
I. Hernández-Pérez ◽  
J. Xamán ◽  
...  

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1656 ◽  
Author(s):  
Mehdi Ghalambaz ◽  
Hossein Arasteh ◽  
Ramin Mashayekhi ◽  
Amir Keshmiri ◽  
Pouyan Talebizadehsardari ◽  
...  

This study investigated the laminar convective heat transfer and fluid flow of Al2O3 nanofluid in a counter flow double-pipe heat exchanger equipped with overlapped twisted tape inserts in both inner and outer tubes. Two models of the same (co-swirling twisted tapes) and opposite (counter-swirling twisted tapes) angular directions for the stationary twisted tapes were considered. The computational fluid dynamic simulations were conducted through varying the design parameters, including the angular direction of twisted tape inserts, nanofluid volume concentration, and Reynolds number. It was found that inserting the overlapped twisted tapes in the heat exchanger significantly increases the thermal performance as well as the friction factor compared with the plain heat exchanger. The results indicate that models of co-swirling twisted tapes and counter-swirling twisted tapes increase the average Nusselt number by almost 35.2–66.2% and 42.1–68.7% over the Reynolds number ranging 250–1000, respectively. To assess the interplay between heat transfer enhancement and pressure loss penalty, the dimensionless number of performance evaluation criterion was calculated for all the captured configurations. Ultimately, the highest value of performance evaluation criterion is equal to 1.40 and 1.26 at inner and outer tubes at the Reynolds number of 1000 and the volume fraction of 3% in the case of counter-swirling twisted tapes model.


2013 ◽  
Vol 1 (2) ◽  
pp. 199-213 ◽  
Author(s):  
Allen Hicken

AbstractThis article investigates the emergence of new partisan identities in Thailand. Using data from Thailand's last several elections I trace the emergence of partisanship over the last 15 years, particularly in the north and northeast. The change in the nature of partisanship has helped turn long-simmering tensions into an increasingly intractable political conflict. This mass partisan alignment has upset the equilibrium of Thai politics, transforming what was once an inefficient but modest-stakes game of political horse-trading into a zero sum game with extremely high stakes.


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