Search results for: urban heat island evaluation
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 12963

Search results for: urban heat island evaluation

12453 Spatial Distribution of Heavy Metals in Khark Island-Iran Using Geographic Information System

Authors: Abbas Hani, Maryam Jassasizadeh

Abstract:

The concentrations of Cd, Pb, and Ni were determined from 40 soil samples collected in surface soils of Khark Island. Geostatistic methods and GIS were used to identify heavy metal sources and their spatial pattern. Principal component analysis coupled with correlation between heavy metals showed that level of mentioned heavy metal was lower than the standard level. Then the data obtained from the soil analyzing were studied for the purposes of normal distribution. The best way of interior finding for cadmium and nickel was ordinary kriging and the best way of interpolation of lead was inverse distance weighted. The result of this study help us to understand heavy metals distribution and make decision for remediation of soil pollution.

Keywords: geostatistics, ordinary kriging, heavy metals, GIS, Khark

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12452 Driving Mechanism of Urban Sprawl in Chinese Context from the Perspective of Domestic and Overseas Comparison

Authors: Tingke Wu, Yaping Huang

Abstract:

Many cities in China have been experiencing serious urban sprawl since the 1980s, which pose great challenges to a country with scare cultivated land and huge population. Because of different social and economic context and development stage, driving forces of urban sprawl in China are quite different from developed countries. Therefore, it is of great importance to probe into urban sprawl driving mechanism in Chinese context. By a comparison study of the background and features of urban sprawl between China and developed countries, this research establishes an analytical framework for sprawl dynamic mechanism in China. By literature review and analyzing data from national statistical yearbook, it then probes into the driving mechanism and the primary cause of urban sprawl. The results suggest that population increase, economic growth, traffic and information technology development lead to rapid expansion of urban space; defects of land institution and lack of effective guidance give rise to low efficiency of urban land use. Moreover, urban sprawl is ultimately attributed to imperfections of policy and institution. On this basis, this research puts forward several sprawl control strategies in Chinese context.

Keywords: China, driving forces, driving mechanism, land institution, urban expansion, urban sprawl

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12451 Comparative Study of Experimental and Theoretical Convective, Evaporative for Two Model Distiller

Authors: Khaoula Hidouri, Ali Benhmidene, Bechir Chouachi

Abstract:

The purification of brackish seawater becomes a necessity and not a choice against demographic and industrial growth especially in third world countries. Two models can be used in this work: simple solar still and simple solar still coupled with a heat pump. In this research, the productivity of water by Simple Solar Distiller (SSD) and Simple Solar Distiller Hybrid Heat Pump (SSDHP) was determined by the orientation, the use of heat pump, the simple or double glass cover. The productivity can exceed 1.2 L/m²h for the SSDHP and 0.5 L/m²h for SSD model. The result of the global efficiency is determined for two models SSD and SSDHP give respectively 30%, 50%. The internal efficiency attained 35% for SSD and 60% of the SSDHP models. Convective heat coefficient can be determined by attained 2.5 W/m²°C and 0.5 W/m²°C respectively for SSDHP and SSD models.

Keywords: productivity, efficiency, convective heat coefficient, SSD model, SSDHPmodel

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12450 Spatial Practice Towards Urban Identity: The Shift, Limitation and Contemporary Value of Christopher

Authors: Botao Zhao, Hong Jiang

Abstract:

Christopher Alexander's urban design theory challenges the technical rationality of the empiricism that prevailsin the first half of the 20th century. Alexander emphasizes the wholeness of the city through progressive design, conceptual-based participation, shaping of centrality, and other principles. Based on Christopher Alexander’s comprehensive book “a new theory of urban design” and by combining with other major works, this paper puts Alexander into the history of the post-modern shift of architecture and urban planning in the middle and late 20th century and analyzes the uniqueness of Alexander’s systematization of spatial context. Despite the overemphasis on the initiative of design, Alexander's attempt to discover the “objectivity” of good space -the ability to generate people's urban identity-through an expanded concept of space, and a systematic approach to design restructures the visceral connection between urban space and human. The concept of urban identity is then decomposed into the identity of the physical setting, identity of process, and identity of meaning. Professionals need to learn from the reality and history of urban space to construct spatial“vocabulary libraries” and create the wholeness of the city, and in which process strengthen the subjectivity of the discipline simultaneously, to generate living structures in which urban identity could be ultimately cultivated.

Keywords: christopher alexander, a new theory of urban design, Urban identity, pattern language, urban design

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12449 Effects of Channel Orientation on Heat Transfer in a Rotating Rectangular Channel with Jet Impingement Cooling and Film Coolant Extraction

Authors: Hua Li, Hongwu Deng

Abstract:

The turbine blade's leading edge is usually cooled by jet impingement cooling technology due to the heaviest heat load. For a rotating turbine blade, however, the channel orientation (β, the angle between the jet direction and the rotating plane) could play an important role in influencing the flow field and heat transfer. Therefore, in this work, the effects of channel orientation (from 90° to 180°) on heat transfer in a jet impingement cooling channel are experimentally investigated. Furthermore, the investigations are conducted under an isothermal boundary condition. Both the jet-to-target surface distance and jet-to-jet spacing are three times the jet hole diameter. The jet Reynolds number is 5,000, and the maximum jet rotation number reaches 0.24. The results show that the rotation-induced variations of heat transfer are different in each channel orientation. In the cases of 90°≤β≤135°, a vortex generated in the low-radius region of the supply channel changes the mass-flowrate distribution in each jet hole. Therefore, the heat transfer in the low-radius region decreases with the rotation number, whereas the heat transfer in the high-radius region increases, indicating that a larger temperature gradient in the radial direction could appear in the turbine blade's leading edge. When 135°<β≤180°; however, the heat transfer of the entire stagnant zone decreases with the rotation number. The rotation-induced jet deflection is the primary factor that weakens the heat transfer, and jets cannot reach the target surface at high rotation numbers. For the downstream regions, however, the heat transfer is enhanced by 50%-80% in every channel orientation because the dead zone is broken by the rotation-induced secondary flow in the impingement channel.

Keywords: heat transfer, jet impingement cooling, channel orientation, high rotation number, isothermal boundary

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12448 Study on Practice of Improving Water Quality in Urban Rivers by Diverting Clean Water

Authors: Manjie Li, Xiangju Cheng, Yongcan Chen

Abstract:

With rapid development of industrialization and urbanization, water environmental deterioration is widespread in majority of urban rivers, which seriously affects city image and life satisfaction of residents. As an emergency measure to improve water quality, clean water diversion is introduced for water environmental management. Lubao River and Southwest River, two urban rivers in typical plain tidal river network, are identified as technically and economically feasible for the application of clean water diversion. One-dimensional hydrodynamic-water quality model is developed to simulate temporal and spatial variations of water level and water quality, with satisfactory accuracy. The mathematical model after calibration is applied to investigate hydrodynamic and water quality variations in rivers as well as determine the optimum operation scheme of water diversion. Assessment system is developed for evaluation of positive and negative effects of water diversion, demonstrating the effectiveness of clean water diversion and the necessity of pollution reduction.

Keywords: assessment system, clean water diversion, hydrodynamic-water quality model, tidal river network, urban rivers, water environment improvement

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12447 Urban Land Expansion Impact Assessment on Agriculture Land in Kabul City, Afghanistan

Authors: Ahmad Sharif Ahmadi, Yoshitaka Kajita

Abstract:

Kabul city is experiencing urban land expansion in an unprecedented scale, especially since the last decade. With massive population expansion and fast economic development, urban land has increasingly expanded and encroached upon agriculture land during the urbanization history of the city. This paper evaluates the integrated urban land expansion impact on agriculture land in Kabul city since the formation of the basic structure of the city between 1962-1964. The paper studies the temporal and spatial characteristic of agriculture land and agriculture land loss in Kabul city using geographic information system (GIS) and remote sensing till 2008. Many temporal Landsat Thematic Mapper (TM) imageries were interpreted to detect the temporal and spatial characteristics of agriculture land loss. Different interval study periods, however, had vast difference in the agriculture land loss which is due to the urban land expansion trends in the city. the high number of Agriculture land adjacent to the city center and urban fringe have been converted into urban land during the study period in the city, as the agriculture land is highly correlated with the urban land.

Keywords: agriculture land, agriculture land loss, Kabul city, urban land expansion, urbanization

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12446 Heat Transfer Correlations for Exhaust Gas Flow

Authors: Fatih Kantas

Abstract:

Exhaust systems are key contributors to ground vehicles as a heat source. Understanding heat transfer in exhaust systems is related to defining effective parameter on heat transfer in exhaust system. In this journal, over 20 Nusselt numbers are investigated. This study shows advantages and disadvantages of various Nusselt numbers in different range Re, Pr and pulsating flow amplitude and frequency. Also (CAF) Convective Augmentation Factors are defined to correct standard Nusselt number for geometry and location of exhaust system. Finally, optimum Nusselt number and Convective Augmentation Factors are recommended according to Re, Pr and pulsating flow amplitude and frequency, geometry and location effect of exhaust system.

Keywords: exhaust gas flow, heat transfer correlation, Nusselt, Prandtl, pulsating flow

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12445 Semi-Analytic Method in Fast Evaluation of Thermal Management Solution in Energy Storage System

Authors: Ya Lv

Abstract:

This article presents the application of the semi-analytic method (SAM) in the thermal management solution (TMS) of the energy storage system (ESS). The TMS studied in this work is fluid cooling. In fluid cooling, both effective heat conduction and heat convection are indispensable due to the heat transfer from solid to fluid. Correspondingly, an efficient TMS requires a design investigation of the following parameters: fluid inlet temperature, ESS initial temperature, fluid flow rate, working c rate, continuous working time, and materials properties. Their variation induces a change of thermal performance in the battery module, which is usually evaluated by numerical simulation. Compared to complicated computation resources and long computation time in simulation, the SAM is developed in this article to predict the thermal influence within a few seconds. In SAM, a fast prediction model is reckoned by combining numerical simulation with theoretical/empirical equations. The SAM can explore the thermal effect of boundary parameters in both steady-state and transient heat transfer scenarios within a short time. Therefore, the SAM developed in this work can simplify the design cycle of TMS and inspire more possibilities in TMS design.

Keywords: semi-analytic method, fast prediction model, thermal influence of boundary parameters, energy storage system

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12444 A Comparative Study of Localized Rainfall and Air Pollution between the Urban Area of Sungai Penchala with Sub-Urban and Green Area in Malaysia

Authors: Mohd N. Ahmad, Lariyah Mohd Sidek

Abstract:

The study had shown that Sungai Penchala (urban) was experiencing localized rainfall and hazardous air pollution due to urbanization. The high rainfall that partly added by localized rain had been seen as a threat of causing the flash floods and water quality deterioration in the area. The air pollution that consisted of mainly particulate matter (PM10), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3) gave an alarming air pollution index (API) to the surrounding area. Comparison among urban area (Sungai Penchala), sub-urban (Gombak), and green areas (Jerantut plus Temerloh) with respect to the rainfall parameters and air pollutants, it was found that the degree of intensities of the parameters was positively related with the urbanization. The air pollutants especially NO2, SO2, and CO were in tandem with the increase of the rainfall. Specifically, if the water catchment area is physically near to the urban area, then the authorities need to look into related urban development program by considering the management of emitted pollutants with respect to the ecological setting of the urban area.

Keywords: urbanization, green area localized rainfall, air pollution, sub-urban area

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12443 Optimization of Heat Insulation Structure and Heat Flux Calculation Method of Slug Calorimeter

Authors: Zhu Xinxin, Wang Hui, Yang Kai

Abstract:

Heat flux is one of the most important test parameters in the ground thermal protection test. Slug calorimeter is selected as the main sensor measuring heat flux in arc wind tunnel test due to the convenience and low cost. However, because of excessive lateral heat transfer and the disadvantage of the calculation method, the heat flux measurement error of the slug calorimeter is large. In order to enhance measurement accuracy, the heat insulation structure and heat flux calculation method of slug calorimeter were improved. The heat transfer model of the slug calorimeter was built according to the energy conservation principle. Based on the heat transfer model, the insulating sleeve of the hollow structure was designed, which helped to greatly decrease lateral heat transfer. And the slug with insulating sleeve of hollow structure was encapsulated using a package shell. The improved insulation structure reduced heat loss and ensured that the heat transfer characteristics were almost the same when calibrated and tested. The heat flux calibration test was carried out in arc lamp system for heat flux sensor calibration, and the results show that test accuracy and precision of slug calorimeter are improved greatly. In the meantime, the simulation model of the slug calorimeter was built. The heat flux values in different temperature rise time periods were calculated by the simulation model. The results show that extracting the data of the temperature rise rate as soon as possible can result in a smaller heat flux calculation error. Then the different thermal contact resistance affecting calculation error was analyzed by the simulation model. The contact resistance between the slug and the insulating sleeve was identified as the main influencing factor. The direct comparison calibration correction method was proposed based on only heat flux calibration. The numerical calculation correction method was proposed based on the heat flux calibration and simulation model of slug calorimeter after the simulation model was solved by solving the contact resistance between the slug and the insulating sleeve. The simulation and test results show that two methods can greatly reduce the heat flux measurement error. Finally, the improved slug calorimeter was tested in the arc wind tunnel. And test results show that the repeatability accuracy of improved slug calorimeter is less than 3%. The deviation of measurement value from different slug calorimeters is less than 3% in the same fluid field. The deviation of measurement value between slug calorimeter and Gordon Gage is less than 4% in the same fluid field.

Keywords: correction method, heat flux calculation, heat insulation structure, heat transfer model, slug calorimeter

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12442 Can Urbanisation Be the Cause for Increasing Urban Poverty: An Exploratory Analysis for India

Authors: Sarmistha Singh

Abstract:

An analysis of trend of urbanization and urban poverty in recent decades is showing that a distinctly reducing rural poverty and increasing in urban areas. It can be argued that the higher the urbanization fuelled by the urban migration to city, which is picking up people from less skilled, education so they faced obstacle to enter into the mainstream economy of city. The share of workforce in economy is higher; in contrast it remains as negligence. At the same time, less wages, absence of social security, social dialogue make them insecure. The vulnerability in their livelihood found. So the paper explores the relation of urbanization and urban poverty in the city, in other words how the urbanization process affecting the urban space in creating the number of poor people in the city. The central focus is the mobility of people with less education and skilled with motive of job search and better livelihood. In many studies found the higher the urbanization and higher the urban poverty in city. In other words, poverty is the impact of urbanization. The strategy of urban inequality through ‘dispersal of concentration’ by the World Bank and others, need to be examined.

Keywords: urbanization, mobility, urban poverty, informal settlements, informal worker

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12441 Heat Transfer Characteristics of Film Condensation

Authors: M. Mosaad, J. H. Almutairi, A. S. Almutairi

Abstract:

In this paper, saturated-vapour film condensation on a vertical wall with the backside cooled by forced convection is analyzed as a conjugate problem. In the analysis, the temperature and heat flux at the wall sides are assumed unknown and determined from the solution. The model is presented in a dimensionless form to take a broad view of the solution. The dimensionless variables controlling this coupled heat transfer process are discovered from the analysis. These variables explain the relative impact of the interactive heat transfer mechanisms of forced convection and film condensation. The study shows that the conjugate treatment of film condensation process yields results different from that predicted by a non-conjugate Nusselt-type solution, wherein the effect of the cooling fluid is neglected.

Keywords: film condensation, forced convection, coupled heat transfer, analytical modelling

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12440 Management of Urine Recovery at the Building Level

Authors: Joao Almeida, Ana Azevedo, Myriam Kanoun-Boule, Maria Ines Santos, Antonio Tadeu

Abstract:

The effects of the increasing expansion of cities and climate changes have encouraged European countries and regions to adopt nature-based solutions with ability to mitigate environmental issues and improve life in cities. Among these strategies, green roofs and urban gardens have been considered ingenious solutions, since they have the desirable potential to improve air quality, prevent floods, reduce the heat island effect and restore biodiversity in cities. However, an additional consumption of fresh water and mineral nutrients is necessary to sustain larger green urban areas. This communication discusses the main technical features of a new system to manage urine recovery at the building level and its application in green roofs. The depletion of critical nutrients like phosphorus constitutes an emergency. In turn, their elimination through urine is one of the principal causes for their loss. Thus, urine recovery in buildings may offer numerous advantages, constituting a valuable fertilizer abundantly available in cities and reducing the load on wastewater treatment plants. Although several urine-diverting toilets have been developed for this purpose and some experiments using urine directly in agriculture have already been carried out in Europe, several challenges have emerged with this practice concerning collection, sanitization, storage and application of urine in buildings. To our best knowledge, current buildings are not designed to receive these systems and integrated solutions with ability to self-manage the whole process of urine recovery, including separation, maturation and storage phases, are not known. Additionally, if from a hygiene point of view human urine may be considered a relatively safe fertilizer, the risk of disease transmission needs to be carefully analysed. A reduction in microorganisms can be achieved by storing the urine in closed tanks. However, several factors may affect this process, which may result in a higher survival rate for some pathogens. In this work, urine effluent was collected under real conditions, stored in closed containers and kept in climatic chambers under variable conditions simulating cold, temperate and tropical climates. These samples were subjected to a first physicochemical and microbiological control, which was repeated over time. The results obtained so far suggest that maturation conditions were reached for all the three temperatures and that a storage period of less than three months is required to achieve a strong depletion of microorganisms. The authors are grateful for the Project WashOne (POCI-01-0247-FEDER-017461) funded by the Operational Program for Competitiveness and Internationalization (POCI) of Portugal 2020, with the support of the European Regional Development Fund (FEDER).

Keywords: sustainable green roofs and urban gardens, urban nutrient cycle, urine-based fertilizers, urine recovery in buildings

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12439 The Management of Urban Facilities in the City of Chlef

Authors: Belakhdar Salah Brahim

Abstract:

The Urban management is a major element of social control of public space and thus the functioning of society. As such, it is a key element of a social conception of sustainable development. Also, it is a cross-cutting sector that relies on land management, infrastructure management, habitat management, management of social services, the management of economic development, etc. This study aims to study how urban management focusing on the study of problems related to urban waste management in developing countries. It appears from the study that the city management is to improve infrastructure and urban services in order to increase the city's development and improve living conditions in cities. It covers various aspects including management of urban space, economic management, administrative management, asset management or infrastructure and finally waste management. Environmental management is important because it solves the pollution problems of life and preserve resources for future generations. Changing perceptions of waste has led to the definition of new policies for integrated waste management requirements appropriate to the urban site.

Keywords: urbanization, urban management, environmental management, waste management

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12438 Evaluation of Green Infrastructure with Different Woody Plants Practice and Benefit Using the Stormwater Management-HYDRUS Model

Authors: Bei Zhang, Zhaoxin Zhang, Lidong Zhao

Abstract:

Green infrastructures (GIs) for rainwater management can directly meet the multiple purposes of urban greening and non-point source pollution control. To reveal the overall layout law of GIs dominated by typical woody plants and their impact on urban environmental effects, we constructed a HYDRUS-1D and Stormwater management (SWMM) coupling model to simulate the response of typical root woody plant planting methods on urban hydrological. The results showed that the coupling model had high adaptability to the simulation of urban surface runoff control effect under different woody plant planting methods (NSE ≥0.64 and R² ≥ 0.71). The regulation effect on surface runoff showed that the average runoff reduction rate of GIs increased from 60 % to 71 % with the increase of planting area (5% to 25%) under the design rainfall event of the 2-year recurrence interval. Sophora japonica with tap roots was slightly higher than that of without plants (control) and Malus baccata (M. baccata) with fibrous roots. The comprehensive benefit evaluation system of rainwater utilization technology was constructed by using an analytic hierarchy process. The coupling model was used to evaluate the comprehensive benefits of woody plants with different planting areas in the study area in terms of environment, economy, and society. The comprehensive benefit value of planting 15% M. baccata was the highest, which was the first choice for the planting of woody plants in the study area. This study can provide a scientific basis for the decision-making of green facility layouts of woody plants.

Keywords: green infrastructure, comprehensive benefits, runoff regulation, woody plant layout, coupling model

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12437 Investigating the Effective Physical Factors in the Development of Coastal Ecotourism in Southern Islands of Iran: A Case Study of Hendurabi Island, Iran

Authors: Zahra Khodaee

Abstract:

Background and Objective: The attractive potential for tourism in the southern islands of Iran, Kish, and Qeshm and recently Hendurabi, are becoming more and more popular and object of increased attention from the investors. The Iranian coral reef islands, with the exception of Kish and Qeshm, have not undergone sufficient development. The southern islands of Iran have faced two problems with climate change and the desire for the presence of tourists. The lack of proper planning, inefficient management, and lack of adequate knowledge of ecosystems of offshore regions have severely damaged the world natural heritage. This study was conducted to consider the correlation of tourism, development, and ecosystem because there is a need for further addressing the ecotourism in coral islands. Method: Through qualitative research, this paper was used of library studies and field studies and surveying to study the physical (objective-subjective) physical factors of ecotourism development in Honduran Island. Using SPSS software and descriptive-analytical method was shown the results. The survey was conducted with the participation of 150 tourists on Kish islands, who were chosen at random and who expressed their desire to travel to Hendurabi Island. Information was gathered using SPSS software and unique statistical T-test. The questionnaire was put together using AMOS software to ensure that the questions asked were sufficiently relevant. Findings: The results of this study presented that physical factors affecting the development of ecotourism in two categories are objective and subjective factors because IFI factor = 0.911 and CFI Factor = 0.907 into the target community. Discussion and conclusion: The results were satisfactory in that they showed that eco-tourists attached importance to see views, quiet, secluded areas, tranquility security, quality of the area being visited, easy access to services these were the top criteria for those visiting the area while they adhere to environmental compliance. Developing Management of these regions should maintain appropriate utilization along with sustainable and ecological responsibility.

Keywords: ecotourism, coral reef island, development management, Hendurabi Island

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12436 Simulation and Experimentation Investigation of Infrared Non-Destructive Testing on Thermal Insulation Material

Authors: Bi Yan-Qiang, Shang Yonghong, Lin Boying, Ji Xinyan, Li Xiyuan

Abstract:

The heat-resistant material has important application in the aerospace field. The reliability of the connection between the heat-resisting material and the body determines the success or failure of the project. In this paper, lock-in infrared thermography non-destructive testing technology is used to detect the stability of the thermal-resistant structure. The phase relationship between the temperature and the heat flow is calculated by the numerical method, and the influence of the heating frequency and power is obtained. The correctness of the analysis is verified by the experimental method. Through the research, it can provide the basis for the parameter setting of heat flux including frequency and power, improve the efficiency of detection and the reliability of connection between the heat-resisting material and the body.

Keywords: infrared non-destructive, thermal insulation material, reliability, connection

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12435 Experimental on Free and Forced Heat Transfer and Pressure Drop of Copper Oxide-Heat Transfer Oil Nanofluid in Horizontal and Inclined Microfin Tube

Authors: F. Hekmatipour, M. A. Akhavan-Behabadi, B. Sajadi

Abstract:

In this paper, the combined free and forced convection heat transfer of the Copper Oxide-Heat Transfer Oil (CuO-HTO) nanofluid flow in horizontal and inclined microfin tubes is studied experimentally. The flow regime is laminar, and pipe surface temperature is constant. The effect of nanoparticle and microfin tube on the heat transfer rate is investigated with the Richardson number which is between 0.1 and 0.7. The results show an increasing nanoparticle concentration between 0% and 1.5% leads to enhance the combined free and forced convection heat transfer rate. According to the results, five correlations are proposed to provide estimating the free and forced heat transfer rate as the increasing Richardson number from 0.1 to 0.7. The maximum deviation of both correlations is less than 16%. Moreover, four correlations are suggested to assess the Nusselt number based on the Rayleigh number in inclined tubes from 1800000 to 7000000. The maximum deviation of the correlation is almost 16%. The Darcy friction factor of the nanofluid flow has been investigated. Furthermore, CuO-HTO nanofluid flows in inclined microfin tubes.

Keywords: nanofluid, heat transfer oil, mixed convection, inclined tube, laminar flow

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12434 Polygeneration Solar Thermal System

Authors: S. K. Deb, B. C. Sarma

Abstract:

The concentrating solar thermal devices using low cost thin metallic reflector sheet of moderate reflectance can generate heat both at higher temperature for the receiver at it’s focus and at moderate temperature through direct solar irradiative heat absorption by the reflector sheet itself. Investigation on well insulated rear surface of the concentrator with glass covers at it’s aperture plane for waste heat recovery against the conventional radiative, convective & conductive heat losses for a bench model with a thermal analysis is the prime motivation of this study along with an effort to popularize a compact solar thermal polygeneration system.

Keywords: concentrator, polygeneration, aperture, renewable energy, exergy, solar energy

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12433 Theoretical and Experimental Investigation of Heat Pipes for Solar Collector Applications

Authors: Alireza Ghadiri, Soheila Memarzadeh, Arash Ghadiri

Abstract:

Heat pipes are efficient heat transfer devices for solar hot water heating systems. However, the effective downward transfer of solar energy in an integrated heat pipe system provides increased design and implementation options. There is a lack of literature about flat plate wicked assisted heat pipe solar collector, especially with the presence of finned water-cooled condenser wicked heat pipes for solar energy applications. In this paper, the consequence of incorporating fins arrays into the condenser region of screen mesh heat pipe solar collector is investigated. An experimental model and a transient theoretical model are conducted to compare the performances of the solar heating system at a different period of the year. A good agreement is shown between the model and the experiment. Two working fluids are investigated (water and methanol) and results reveal that water slightly outperforms methanol with a collector instantaneous efficiency of nearly 60%. That modest improvement is achieved by adding fins to the condenser region of the heat pipes. Results show that the collector efficiency increase as the number of fins increases (upon certain number) and reveal that the mesh number is an important factor which affect the overall collector efficiency. An optimal heat pipe mesh number of 100 meshes/in. With two layers appears to be favorable in such collectors for their design and operating conditions.

Keywords: heat pipe, solar collector, capillary limit, mesh number

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12432 Accessibility to Urban Parks for Low-income Residents in Chongqing, China: Perspective from Relative Deprivation

Authors: Junhang Luo

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With the transformation of spatial structure and the deepening of urban development, the demand for a better life and the concerns for social resources equities of residents are increasing. As an important social resource, park plays an essential role in building environmentally sustainable cities. Thus, it is important to examine park accessibility for low-income and how it works in relative deprivation, so as to provide all residents with equitable services. Using the network and buffer methods of GIS, this paper analyzes urban park accessibility for low-income residents in Chongqing, China. And then conduct a satisfaction evaluation of park resource accessibility with low-incomes through questionnaire surveys from deprivation dimensions. Results show that the level of park accessibility in Chongqing varies significantly and the degree of relative deprivation is relatively high. Public transportation convenience improves and the number of community park increases contribute positively to improving park accessibility and alleviating the relative deprivation of public resources. Combined with the innovation pattern of social governance in China, it suggests that urban park accessibility needs to be jointly governed and optimized by multiple social resources from the government to the public, and the service efficiency needs the index system and planning standards according to local conditions to improve quality and promote equity. At the same time, building a perfect park system and complete legislation assurance system will also play a positive role in ensuring that all residents can enjoy the urban public space more fairly, especially low-income groups.

Keywords: urban park, accessibility, relative deprivation, GIS network analysis, chongqing

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12431 Using Nature-Based Solutions to Decarbonize Buildings in Canadian Cities

Authors: Zahra Jandaghian, Mehdi Ghobadi, Michal Bartko, Alex Hayes, Marianne Armstrong, Alexandra Thompson, Michael Lacasse

Abstract:

The Intergovernmental Panel on Climate Change (IPCC) report stated the urgent need to cut greenhouse gas emissions to avoid the adverse impacts of climatic changes. The United Nations has forecasted that nearly 70 percent of people will live in urban areas by 2050 resulting in a doubling of the global building stock. Given that buildings are currently recognised as emitting 40 percent of global carbon emissions, there is thus an urgent incentive to decarbonize existing buildings and to build net-zero carbon buildings. To attain net zero carbon emissions in communities in the future requires action in two directions: I) reduction of emissions; and II) removal of on-going emissions from the atmosphere once de-carbonization measures have been implemented. Nature-based solutions (NBS) have a significant role to play in achieving net zero carbon communities, spanning both emission reductions and removal of on-going emissions. NBS for the decarbonisation of buildings can be achieved by using green roofs and green walls – increasing vertical and horizontal vegetation on the building envelopes – and using nature-based materials that either emit less heat to the atmosphere thus decreasing photochemical reaction rates, or store substantial amount of carbon during the whole building service life within their structure. The NBS approach can also mitigate urban flooding and overheating, improve urban climate and air quality, and provide better living conditions for the urban population. For existing buildings, de-carbonization mostly requires retrofitting existing envelopes efficiently to use NBS techniques whereas for future construction, de-carbonization involves designing new buildings with low carbon materials as well as having the integrity and system capacity to effectively employ NBS. This paper presents the opportunities and challenges in respect to the de-carbonization of buildings using NBS for both building retrofits and new construction. This review documents the effectiveness of NBS to de-carbonize Canadian buildings, identifies the missing links to implement these techniques in cold climatic conditions, and determine a road map and immediate approaches to mitigate the adverse impacts of climate change such as urban heat islanding. Recommendations are drafted for possible inclusion in the Canadian building and energy codes.

Keywords: decarbonization, nature-based solutions, GHG emissions, greenery enhancement, buildings

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12430 Numerical Modeling of Film Cooling of the Surface at Non-Uniform Heat Flux Distributions on the Wall

Authors: M. V. Bartashevich

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The problem of heat transfer at thin laminar liquid film is solved numerically. A thin film of liquid flows down an inclined surface under conditions of variable heat flux on the wall. The use of thin films of liquid allows to create the effective technologies for cooling surfaces. However, it is important to investigate the most suitable cooling regimes from a safety point of view, in order, for example, to avoid overheating caused by the ruptures of the liquid film, and also to study the most effective cooling regimes depending on the character of the distribution of the heat flux on the wall, as well as the character of the blowing of the film surface, i.e., the external shear stress on its surface. In the statement of the problem on the film surface, the heat transfer coefficient between the liquid and gas is set, as well as a variable external shear stress - the intensity of blowing. It is shown that the combination of these factors - the degree of uniformity of the distribution of heat flux on the wall and the intensity of blowing, affects the efficiency of heat transfer. In this case, with an increase in the intensity of blowing, the cooling efficiency increases, reaching a maximum, and then decreases. It is also shown that the more uniform the heating of the wall, the more efficient the heat sink. A separate study was made for the flow regime along the horizontal surface when the liquid film moves solely due to external stress influence. For this mode, the analytical solution is used for the temperature at the entrance region for further numerical calculations downstream. Also the influence of the degree of uniformity of the heat flux distribution on the wall and the intensity of blowing of the film surface on the heat transfer efficiency was also studied. This work was carried out at the Kutateladze Institute of Thermophysics SB RAS (Russia) and supported by FASO Russia.

Keywords: Heat Flux, Heat Transfer Enhancement, External Blowing, Thin Liquid Film

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12429 Research on the Application of Renewability in the Construction Model of Zhejiang Rural Revitalization

Authors: Zheng Junchao, Wang Zhu

Abstract:

With the advancement of China's urbanization process, the Chinese government has put forward the strategy of rural revitalization which is aiming at realizing the comprehensive integration of urban and rural areas and the comprehensive revitalization of rural areas. The path of rural revitalization in Zhejiang province put forward a typical model from four dimensions: suburban area, plain, island and mountain area. Research methods include on-the-spot investigation, visiting a number of successful demonstration villages in Zhejiang and interviewing village officials. Based on the location conditions, resource endowments, industrial forms and development foundations of Zhejiang Province, this paper introduces in detail the model of rural revitalization in Zhejiang Province and the challenges it encounters, as well as the role of building construction. The rural development model of Zhejiang province makes the rural culture flourish. Taking the construction of rural scenic spots as the carrier, the rural culture, and natural landscape are constantly improved. It provides a model and template for the country's rural revitalization. The promotion of Zhejiang rural revitalization model will improve the current rural landscape, living standard and industrial structure, which will narrow the urban-rural gap greatly.

Keywords: comprehensive rural revitalization, Zhejiang model, reproducible, comprehensive integration

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12428 The Mechanism of Upgrading and Urban Development in the Egyptian City: Case Study of Damietta

Authors: Lina Fayed Amin

Abstract:

The research studied, in the beginning, the related urban concepts such as the urban, development, urban development. As it also deals with the upgrading, urban upgrading, community participation and the role of local administration in development and upgrading projects. Then it studies some regional upgrading & urban development projects in Egypt followed by international projects, and the analysis the strategies followed in dealing with these projects. Afterwards, we state the regional aspects of both Damietta governorate & city, dealing with its potentials & development constraints. Followed by studying the upgrading and urban development projects strategies in reflection to the city’s crucial problems, and the constraints that faced the upgrading & development project. Then, it studied the implementation of the project’s strategies & it provided the financial resources needed for the development project in Damietta city. Followed by the studying of the urban and human development projects in the upgrading of Damietta city, as well as analyzing the different projects &analyzing the results of these projects on the aspects of the city’s needs. Then the research analysis in comparison the upgrading and urban development project in Damietta and the regional upgrading and development projects in Egypt. As well as the comparison between the upgrading and urban development project and the international projects in some Arabic and foreign countries in relation to the goals, problems, obstacles, the community participation, the finance resources and the results. Finally, it reviews the results and recommendations that were reached as a result of studying the similar urban upgrading projects in Egypt and in some Arabic and foreign countries. Followed by the analytical analysis of the upgrading and urban development in Egypt

Keywords: Damietta city, urban development, upgrading mechanisms, urban upgrading

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12427 Microclimate Impacts on Solar Panel Power Generation in Midlands Area, UK

Authors: Stamatis Zoras, Boris Ceranic, Ashley Redfern

Abstract:

Green House Gas emissions from domestic properties currently account for a substantial part of the total UK’s carbon emissions and is a priority area for UK to reach zero carbon emissions. However, GHG emissions of urban complexes depend on building, road, structural developments etc surfaces that form urban microclimate. This in turn may further influence renewable energy system power generation that depend on solar or wind potential. Moreover, urban climatic conditions are also influenced by the installation of those power generation systems that may impact their own power generation efficiency. Increased air temperature is attributed to densely installed roof based solar panels that consequently impact their own production efficiency. Installation of roof based solar panels requires adequate guidance to enable housing businesses, councils and organisations to implement sufficient measures for improved power generation in relation to local urban microclimate. How microclimate is affected and how, in return, it affects solar power productivity. Derby Council & Derby Homes have been collecting solar panel power generation data for a large number of properties. The different building areas and system operation performance will be studied against microclimate conditions through time. It is envisaged that the outcomes of the study will support a working up strategy for Derby city to ensure that owned homes would be able to access information and data of solar photo voltaic PV and solar thermal panels potential on social housing, helping residents on low incomes create their own green energy to power their homes and heat their homeshot water.

Keywords: microclimate, solar power, urban climatology, urban morphology

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12426 Influence of Gravity on the Performance of Closed Loop Pulsating Heat Pipe

Authors: Vipul M. Patel, H. B. Mehta

Abstract:

Closed Loop Pulsating Heat Pipe (CLPHP) is a passive two-phase heat transfer device having potential to achieve high heat transfer rates over conventional cooling techniques. It is found in electronics cooling due to its outstanding characteristics such as excellent heat transfer performance, simple, reliable, cost effective, compact structure and no external mechanical power requirement etc. Comprehensive understanding of the thermo-hydrodynamic mechanism of CLPHP is still lacking due to its contradictory results available in the literature. The present paper discusses the experimental study on 9 turn CLPHP. Inner and outer diameters of the copper tube are 2 mm and 4 mm respectively. The lengths of the evaporator, adiabatic and condenser sections are 40 mm, 100 mm and 50 mm respectively. Water is used as working fluid. The Filling Ratio (FR) is kept as 50% throughout the investigations. The gravitational effect is studied by placing the evaporator heater at different orientations such as horizontal (90 degree), vertical top (180 degree) and bottom (0 degree) as well as inclined top (135 degree) and bottom (45 degree). Heat input is supplied in the range of 10-50 Watt. Heat transfer mechanism is natural convection in the condenser section. Vacuum pump is used to evacuate the system up to 10-5 bar. The results demonstrate the influence of input heat flux and gravity on the thermal performance of the CLPHP.

Keywords: CLPHP, gravity effect, start up, two-phase flow

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12425 A Short Survey of Integrating Urban Agriculture and Environmental Planning

Authors: Rayeheh Khatami, Toktam Hanaei, Mohammad Reza Mansouri Daneshvar

Abstract:

The growth of the agricultural sector is known as an essential way to achieve development goals in developing countries. Urban agriculture is a way to reduce the vulnerability of urban populations of the world toward global environmental change. It is a sustainable and efficient system to respond to the environmental, social and economic needs of the city, which leads to urban sustainability. Today, many local and national governments are developing urban agriculture as an effective tool in responding to challenges such as poverty, food security, and environmental problems. In this study, we follow a perspective based on urban agriculture literature in order to indicate the urban agriculture’s benefits in environmental planning strategies in non-western countries like Iran. The methodological approach adopted is based on qualitative approach and documentary studies. A total of 35 articles (mixed quantitative and qualitative methods studies) were studied in final analysis, which are published in relevant journals that focus on this subject. Studies show the wide range of positive benefits of urban agriculture on food security, nutrition outcomes, health outcomes, environmental outcomes, and social capital. However, there was no definitive conclusion about the negative effects of urban agriculture. This paper provides a conceptual and theoretical basis to know about urban agriculture and its roles in environmental planning, and also conclude the benefits of urban agriculture for researchers, practitioners, and policymakers who seek to create spaces in cities for implementation urban agriculture in future.

Keywords: urban agriculture, environmental planning, urban planning, literature

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12424 Evaluation of Planned and Organically Transformed Public Spaces in Urban Indian Market Places: A Case of Bhopal City, India

Authors: Piyush Hajela

Abstract:

Public spaces within Indian markets are vibrant, colorful and contain dimensions that make them attractive and therefore act as popular gathering spaces. Most of these public spaces emerge as squares, plazas of varied shapes and sizes spread at different locations within the market. These public spaces grow organically and are discovered by the people themselves as they respond positively to the collective human senses. On the other hand, there are the planned and designed public spaces as well that are less active. This research evaluates both the planned and the organically transformed public spaces in Indian markets from an Urban Design point of view. The purpose of such research is to provide a basis for design solutions to ensure the success of designed public spaces. The evaluation is done for identified Attributes, namely Comfort, Protection, Familiarity, Activities, Form, Legibility, Engagement, Safety, Accessibility, Environment and Transformations by which a Public Space attains its recognition. The evaluation is based on a rating done for forty-four parameters falling under eleven attributes of public space. An opinion survey of professionals is conducted for their priorities of attributes while designing Public spaces. A comparison is made to rank these attributes between Planned and Organically transformed Public spaces and, opinion of the professionals. After dues analysis, the research suggests the learning from the organically transformed Public spaces for ensuring the success of designed public spaces. The suggestions may be in the form of Design decisions or administrative regulations, or both for achieving the desirables.

Keywords: assessment, attributes, engagement, interaction

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