Cálculo y diseño de ventiladores centrifugos para un sistema de enfriamiento por evaporación

Detalla el diseño y construcción de ventiladores que son utilizados no solamente en evaporadores, sino en un sin número de aplicaciones dentro de la industria. esta tesis presenta un método practico de diseño de enfriadores por evaporación y sus ventiladores utilizando un modelo a escala, para luego mediante similitud dinámica completar el proceso de diseño. adicionalmente se presenta el análisis de costo de fabricación del equipo y los planos constructivos del mismo.GuayaquilIngeniero Mecánic

Cálculo y diseño de empaquetadura y ventiladores para una torre de enfriamiento de tiro forzado

En el siguiente artículo se trata de mostrar un método práctico y eficiente no solamente para calcular los ventiladores de una torre de enfriamiento, sino para diseñar el equipo como tal. Se utiliza la experimentación para determinar el coeficiente de transferencia de calor de la empaquetadura y luego se dimensiona los ventiladores utilizando el escalamiento por el método de similitud dinámica

Diminishing benefits of urban living for children and adolescents’ growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified