Two-sided windcatcher in low wind speed environment

Global warming is a major threat and is mainly caused by emission of greenhouse gases. The building construction sector or buildings are accountable for about 40% of total greenhouse gases due to energy consumption. The application of air conditioning systems is reported to reach 70% of this energy consumption. In contrast, natural ventilation systems such as windcatcher are a promising passive cooling alternative that not only improve indoor air quality (IAQ) and thermal comfort but also reduce energy consumption. However, the efficiency of windcatcher is hindered by two factors: air short-circuit phenomenon and low ambient wind speed. The aim of this research is to develop a new windcatcher design that addresses both problems by integration of wing wall and installation of a new device called anti-short circuit device (ASCD). Based on review of literature, wing wall and ASCD can enhance the performance of windcatcher in low wind speed. To achieve this aim, two methods namely wind tunnel testing and simulation using computational fluid dynamics (CFD) were explored. The results showed that the difference between the CFD and experimental results was within the acceptable range. Integration of wing wall and ASCD to the windcatcher improved the IAQ factors such as air flow rate, air change rate and air velocity. It was observed that the ventilation performance of the new design in 45o wind incident angle was better than the 0o wind incident angle. In conclusion, this study has proven that the new design can effectively be implemented to improve the ventilation and IAQ

Comparative analysis of exhaust gases from MF285 and U650 tractors under field conditions

Agricultural machinery is an important source of emission of air pollutant in rural locations.  This work deals with the effects of types of tractors and operation conditions on engine emission.  The values of some exhaust gases (HC, CO, CO2, O2 and NO) from two common tractors (MF285 and U650) at three situations (use of ditcher, plowing and cultivator) were evaluated in the West of IRAN (Kermanshah).  In addition, engine oil temperature at operation conditions was measured.  Also results showed the values of exhaust HC and O2 of MF285 are lower than U650, while the other exhausts gases (CO, CO2, and NO) of MF285 are higher than U650.  Value of NO emission increased as engine oil temperature increased.  All of exhaust gases except CO have a significant relationship with type of tractors, while all of measured gases have a significant relationship with installed instruments at 1%.   Keywords: environmental pollution, exhaust gases, tracto

Measurement and Analysis of Vibration of Operator in Universal 650, Massey Ferguson 285 & MF 299 Tractors

Abstract Since healthy human is basis of permanent development in any society, and safety & health subject have special importance, then examination and investigation is necessary about of risks working for the purpose of recognition danger and guiding to eliminate them. In this study, object is to compare effect of change engine rotation and ground type on operator of tractors and implements that utilized. In other words, the goal is to measurement and analysis of transmitted vibration on different parts of human body. In this investigation universal tractor and ferguson285 &299 tractors with moldboard plough and disk are used. Hand-Arm vibration's operator in 1300, 1500 and 1700 rpm and in ploughing field and unploughing field with hand-arm vibration meter are measured. After statistical analysis, appeared that effective vibration difference on hand and arm's operator in examined tractors is significant and engine rotation is significant too

A review of numerical modelling of multi-scale wind turbines and their environment

Global demand for energy continues to increase rapidly, due to economic and population growth, especially for increasing market economies. These lead to challenges and worries about energy security that can increase as more users need more energy resources. Also, higher consumption of fossil fuels leads to more greenhouse gas emissions, which contribute to global warming. Moreover, there are still more people without access to electricity. Several studies have reported that one of the rapidly developing source of power is wind energy and with declining costs due to technology and manufacturing advancements and concerns over energy security and environmental issues, the trend is predicted to continue. As a result, tools and methods to simulate and optimize wind energy technologies must also continue to advance. This paper reviews the most recently published works in Computational Fluid Dynamic (CFD) simulations of micro to small wind turbines, building integrated with wind turbines, and wind turbines installed in wind farms. In addition, the existing limitations and complications included with the wind energy system modelling were examined and issues that needs further work are highlighted. This study investigated the current development of CFD modelling of wind energy systems. Studies on aerodynamic interaction among the atmospheric boundary layer or wind farm terrain and the turbine rotor and their wakes were investigated. Furthermore, CFD combined with other tools such as blade element momentum were examined

A critical review of windcatcher ventilation: Micro-environment, techno-economics, and commercialisation

Windcatcher natural ventilation is a low-energy approach that can provide effective ventilation during favourable weather conditions. When combined with different cooling, heating, and dehumidification technologies, windcatchers can provide enhanced indoor environment quality. This work provides a critical review of windcatchers' performance. It covers aspects such as ventilation, thermal comfort, overheating risk, indoor air quality (IAQ), energy performance, economic cost, and life cycle assessment (LCA). Although many studies have investigated windcatchers' performance in terms of thermal comfort, little attention has been paid to the potential overheating risk. This oversight is particularly important in the context of global warming trends and the increasing likelihood of extreme weather conditions. Moreover, previous studies on windcatchers’ IAQ performance have primarily focused on indoor CO2 concentrations, while the influences of pollutants such as volatile organic compounds (VOCs) have not been reported. The quantification of energy performance for windcatchers remains an underexplored area, and very few studies have conducted economic analyses or LCAs of windcatcher systems. There is a clear need for more field experiments to investigate these aspects comprehensively. This review also provides insights into the current trends and future perspectives in the commercial windcatcher market, including available options, opportunities, and threats. The findings highlight the importance of several factors that must be considered before the large-scale commercial rollout of windcatcher technology. These include the lack of awareness and regulatory incentives, cost considerations, aesthetic preferences, and misconceptions or concerns regarding the effectiveness of windcatchers

Natural ventilation by windcatcher (Badgir): A review on the impacts of geometry, microclimate and macroclimate

The significant energy use and increasing requirement for good indoor environment quality in the built environment have led to a renewed interest in natural ventilation strategies such as windcatchers. Windcatcher is a roof-mounted device that supplies fresh airflow into a room and expels polluted air under the action of wind pressure and buoyancy forces. The aim of this review is to investigate factors which affect the natural ventilation performance of windcatcher including internal factors (related to geometry/design of windcatcher), external building features (microclimate) and surrounding environment (macroclimate) plus the impact of integration with other passive systems. From reviewing the literature, it was found that windcatcher with a square cross-section and curved roof demonstrates better ventilation in the room compared to other configurations. Moreover, the overall findings indicated that the integration of windcatcher with other natural ventilation systems such as solar chimney and wing wall has a considerable effect on the ventilation efficiency. In urban environments, buildings are often located quite close to each other, and the effect of surrounding structures on airflow profile cannot be ignored but only a limited number of works considered the impact of urban environment and objects (upstream or downstream) on the ventilation efficiency of windcatcher. Finally, the impact of vegetation, techno-economic cost and energy saving in a building are some significant gaps of current studies.The authors would like to thank the Advanced Building and Environment Research (ABER) center to support to conduct this research, as well as Academic Research Center (ARC).Scopu

A global review of energy consumption, CO2 emissions and policy in the residential sector (with an overview of the top ten CO2 emitting countries)

Climate change and global warming as the main human societies' threats are fundamentally associated with energy consumption and GHG emissions. The residential sector, representing 27% and 17% of global energy consumption and CO2 emissions, respectively, has a considerable role to mitigate global climate change. Ten countries, including China, the US, India, Russia, Japan, Germany, South Korea, Canada, Iran, and the UK, account for two-thirds of global CO2 emissions. Thus, these countries' residential energy consumption and GHG emissions have direct, significant effects on the world environment. The aim of this paper is to review the status and current trends of energy consumption, CO2 emissions and energy policies in the residential sector, both globally and in those ten countries. It was found that global residential energy consumption grew by 14% from 2000 to 2011. Most of this increase has occurred in developing countries, where population, urbanization and economic growth have been the main driving factors. Among the ten studied countries, all of the developed ones have shown a promising trend of reduction in CO2 emissions, apart from the US and Japan, which showed a 4% rise. Globally, the residential energy market is dominated by traditional biomass (40% of the total) followed by electricity (21%) and natural gas (20%), but the total proportion of fossil fuels has decreased over the past decade. Energy policy plays a significant role in controlling energy consumption. Different energy policies, such as building energy codes, incentives, energy labels have been employed by countries. Those policies can be successful if they are enhanced by making them mandatory, targeting net-zero energy building, and increasing public awareness about new technologies. However, developing countries, such as China, India and Iran, still encounter with considerable growth in GHG emissions and energy consumption, which are mostly related to the absence of strong, efficient policy