Analysis of the urban heat island effects on building energy consumption

Urban areas usually experience higher temperatures when compared to their rural surroundings. Several studies underlined that specific urban conditions are strictly connected with the Urban heat island (UHI) phenomenon, which consists in the environmental overheating related to anthropic activities. As a matter of fact, urban areas, characterized by massive constructions that reduce local vegetation coverage, are subject to the absorption of a great amount of solar radiation (short wave) which is only partially released into the atmosphere by radiation in the thermal infrared (long wave). On the contrary, green areas and rural environments in general show a reduced UHI effect, that is lower air temperatures, due to evapo-transpiration fluxes. Several studies demonstrate that urban microclimate affects buildings’ energy consumption and calculations based on typical meteorological year could misestimate their actual energy consumption. In this study, two different sets of meteorological data are used for the calculation of the heating and cooling energy needs of an existing university building. The building is modeled using TRNSYS v.17 software. The first set of data was collected by a weather station located in the city center of Modena, while the second set of data was collected by another station, located in the surrounding area of the city, near to the studied building. The influence of the different meteorological situations described by the two weather stations are analyzed and assumed to be representative of the UHI effect. Furthermore, the effects of UHI mitigation strategies on the building energy needs are evaluated and discussed

Thermo-Mixed Hydrodynamics of Piston Compression Ring Conjunction

The final publication is available at http://link.springer.com.A new method, comprising Navier-Stokes equations, Rayleigh-Plesset volume fraction equation, an analytical control-volume thermal mixed approach and asperity interactions is reported. The method is employed for prediction of lubricant flow and assessment of friction in the compression ring-cylinder liner conjunction. The results are compared with Reynolds-based laminar flow with Elrod cavitation algorithm. Good conformance is observed for medium load intensity part of the engine cycle. At lighter loads and higher sliding velocity, the new method shows more complex fluid flow, possessing layered flow characteristics on account of pressure and temperature gradient into the depth of the lubricant film, which leads to a cavitation region with vapour content at varied volume fractions. Predictions also conform well to experimental measurements reported by other authors

Reducing urban heat island effects: A systematic review to achieve energy consumption balance

Considering the current energy consumption worldwide, it has become increasingly important to study the effects of urban heat island on energy consumption in order to improve the environment. This paper investigates the impact of Urban Heat Island (UHI) on energy consumption and also determines which factors can directly affect energy use in the city. The UHI current knowledge and literature are reviewed, as well as how UHI can affect energy consumption. This paper explores literally the conceptual framework of confliction between population and urban structure, which produce UHI intensity and affected energy consumption balance. It is then discussed how these two factors can be affected and gives implication to the city and then, focuses on whether actions should be taken for balancing adaptation and mitigation UHI effects. It will be concluded by making the three important strategies to minimise the impact of UHI on energy consumption: providing an appropriate landscape, using appropriate materials on external surfaces of buildings and urban areas and promoting natural ventilation

Hyperuricemia in congenital heart diseases: True or numbers

Background: Uric acid has been shown to be increased in congenital heart diseases (CHD) and Eisenmenger syndrome. The present study was undertaken to investigate the incidence of hyperuricemia, renal dysfunction and the exacerebrating factors in congenital heart diseases (CHD). Methods: We studied prospective cross sectionaly 500 patients, aged one month to 18 years. Blood for serum uric acid, hemoglobin (Hb), hamatocrit (Hct), arterial blood gas (ABG), blood urea nitrogen (BUN), creatinine (Cr) and urinalysis (U/A) as well as pulmonary and aorta arterial pressures were obtained during catheterization. Findings: 24.8% of patients with cyanotic congenital heart diseases (CCHD) had a serum uric acid level of greater than normal, related directly to the degree of polycythemia, but 0.06% in non cyanotic congenital heart diseases. Also 13% of patients with pulmonary hypertension (PH) had hyperuricemia corresponding to PH value. In these groups, hyperuricemia increased parallel to age. 24 % of hyperuricemic cyanotic patients and 10% of hyperuricemic PH had abnormal proteinuria without increased BUN and Cr. Conclusion: Serum uric acid increased proportional to polycythemia and PH in CHD and may cause nephropathy without increase in BUN and Cr

The Impact of Anthropogenic Heat on Formation of Urban Heat Island and Energy Consumption Balance

This paper investigates the impact of anthropogenic heat on formation of urban heat island (UHI) and also determines which factors can directly affect energy use in the city. It explores literally the conceptual framework of confliction between anthropogenic heat and urban structure, which produced UHI intensity and affected energy consumption balance. It then discusses how these two factors can be affected and gives implication to the city and then focuses on whether actions should be taken for balancing adaptation and mitigation of UHI effects. It will be concluded by making the three important strategies to minimise the impact of UHI on energy consumption: landscaping, using albedo materials on external surfaces of buildings and urban areas, and promoting natural ventilation

The Conceptual Framework on Formation of Urban Heat Island in Tehran Metropolitan, Iran : A Focus on Urbanization Factor

In an urban area, one of the great problems is urban heat island effect, which is due to many factors such as urbanization and climatic factors, resulting from the production and accumulation of heat in the urban mass. The main characteristics of UHI effect are the raised temperatures in the city centre, leading to excessive energy use for cooling and putting urban population at great morbidity and mortality risks. Therefore, it becomes increasingly important to study that how could various factors form UHI over the city in order to reduce environmental challenges. This paper, therefore, is focused on urbanization and climatic factors to understand the influence way of these factors on formation of UHI. The percentage of UHI formation is high when great interaction exists. This paper explores literally the conceptual framework of interaction between urbanization and climatic factors on formation of UHI with the case study of city of Tehran. The urbanization factors that affect Tehran are discussed in relation to location of the city, the size of the city and population, density of built-up area, urban geometry, thermal property of fabric, surface waterproofing, anthropogenic heat, air pollution, land use and wind speed