Centralized exhaust system simulation and parameter optimization

This study examines smoke spread in an underground mall fire under the composite smoke control mode of a smoke barrier and a mechanical smoke exhaust system. The objective is to optimize the selection of smoke containment and exhaust methods in an underground mall in Fuxin City, China. A Fire Dynamics Simulator was used for numerical simulation to investigate the effects of the sagging height and spacing of smoke barriers on smoke containment, as well as the effects of size, number, and arrangement of smoke vents in the mechanical smoke exhaust system on the effectiveness of smoke exhaust. The results indicated that a smoke barrier with a sagging height of 1 m and a spacing of 5 m was effective in preventing the spread of high-temperature smoke. When the sagging height of the smoke barrier increased to 1.2 m, the smoke barrier effect was comparable to that of a 1 m height barrier. Regarding the mechanical smoke exhaust system, the size of the opening area of the smoke vent had no significant effect on the smoke exhaust effect. The best smoke exhaust effect was achieved when the number of smoke vents was 12. Additionally, the double-row setting of smoke vents was more efficient than the single-row setting. Combining a smoke barrier and a mechanical smoke exhaust system can provide a more effective smoke control compared to either system alone. Comprehensively, considering the effectiveness and economy of smoke containment and exhaust, the optimal combination of smoke containment and exhaust was determined to be a smoke barrier with a sagging height of 1 m and spacing of 5 m, and a mechanical smoke exhaust system with 12 smoke vents in a double-row arrangement.

Nowadays, the smoke prevention and exhaust system has not been effectively taken seriously, but smoke in fire disasters have become an important cause of death. In this paper, some problems still exist in smoke prevention and exhaust system will be concluded including design inspection and maintains. Meanwhile, a new method of calculating volumetric flow rate of smoke exhaust in high-rise building will be shown. The results show that the the existing prevention and exhaust systems in high-rise buildings have some defects and need to be upgraded. Outdoor wind in high-rise buildings is an important effect of fires. Some significant and easily ignored aspects of inspection and maintains will also be summarized.

Scale-model study of an innovative smoke exhaust system for bidirectional tunnels

본 논문은 초고층건물 화재 시 외기바람의 풍속, 풍향 조건이 기계배연시스템의 배연성능에 미치는 영향을 분석하였으며, 차원해석을 통한 축소모델 설계와 CFD 수치해석을 이용하여 영향을 정량적으로 평가하였다. 해석 결과, 축소모델의 외기풍속 5 m/s(실 외기풍속은 약 16 m/s), 풍향 <TEX>${\theta}=5^{\circ}$</TEX>의 조건의 경우 배연풍속이 최대 약 17% 감소함을 보였으며, 외기풍향 각도 <TEX>${\theta}=25^{\circ}$</TEX> 이하의 조건에서는 기계배연시스템의 배출풍량을 크게 감소시켜 화재시 배연성능이 저하될 수 있는 것으로 평가되었다. This study examined the effects of the wind conditions, such as wind velocity and wind directions, on the performance of the mechanical smoke exhaust systems for high-rise building fires. A scaled model design and CFD simulations were used to verify the effects both quantitatively and qualitatively. The results showed that the smoke exhaust velocity of the mechanical exhaust system can be reduced by up to 17% at a wind velocity of 5 m/s (equivalent to an outdoor wind speed of 16 m/s) and a wind direction of <TEX>${\theta}=5^{\circ}$</TEX>. In addition, the angle of the outdoor wind direction below <TEX>${\theta}=25^{\circ}$</TEX> had a significantly influence on the smoke exhaust flow rate and reduced exhaust performance of the smoke exhaust system in a fire.

This paper suggests a system to reduce suffocation casualties in apartment households by smoke exhaust using the toilet exhaust port adjacent to the outdoor. The opening/closing method of the fire damper attached to the existing systems takes the form “CLOSED” to prevent flame and smoke diffusion, but the method used in the proposed system is contradictory to this method. The results of the legal review of the smoke exhaust system depends on the conformance of the damper performance to legal requirements. Hence, the proposed system can be applied if the damper performance conforms to the legal requirements and the air velocity in the pipe shaft is within the legal velocity limit. However, the exhaust rate of the natural exhaust system must be considered.

Due to its advantages in energy conservation, emission reduction and recyclability, air-supported membrane structure (ASMS) has been widely implemented in various applications, including large stadiums, conference centers, warehouses and temporary buildings.Compared to traditional building, the structural and material properties of ASMS are special which significantly affect smoke diffusion and flow behavior during fire scenarios.Moreover, the design methods for smoke management system of ASMS buildings are still lacked and further research is required.In this study, a numerical model of a coal storage bin was built.The impact of several key design parameters, including such as height of natural smoke vent, fire source location and makeup air methods, on the performance of ASMS building`s smoke management system were evaluated.Gas temperature, CO concentration, visibility, smoke exhausting quantity, critical pyrolysis temperature and critical heat radiation intensity were selected as evaluation indexes.The results indicated that better natural smoke exhaust efficiency was achieved when the natural smoke vents were located at the height between 80% and 100% of the building's total height.Setting natural makeup air vent in the wall of smoke bay 3 can achieve the best cooling effect.However, compared to natural makeup air, the natural smoke exhaust efficiency of mechanical makeup air was much better.When the rate of mechanical makeup air reached 120% of the required natural smoke exhausting quantity, it has significant improvements in temperature reduction, visibility and natural smoke exhausting quantity which are crucial for ensuring safe evacuation during fire events.These findings provide a design refer for enhancing fire protection and construction practices in ASMS buildings.

With the increasing attention of the world to the sustainable development of agriculture and the continuous improvement of people's awareness of environmental protection and food safety, the construction and development of ecological agriculture industry chain has become a research hotspot in the field of agriculture. This study takes the industrial chain of apple eco-agriculture as the object, analyzes the current situation of apple industrial chain on the basis of theoretical cognition of circular economy, food chain and industrial symbiosis, and constructs the internal ecological industrial chain of apple "plant-sales" and the ecological cycle industrial chain of apple "plant-processing". Finally, It is suggested that leading enterprises and e-commerce platforms should be used to strengthen the collectivization degree of farmers, build a green and circular agricultural industry chain, and improve the scientific and technological content of fruits.

With the progress of society, people's awareness of environmental protection is gradually increasing. The sustainable development of society is threatened by many problems, such as resource shortage, global warming and other issues, and miniature electric vehicles play an invaluable role in solving environmental pollution and traffic congestion. The design and development of electric vehicles is even more important. Combined with the social development trend and the concept of green travel, this paper takes the design of micro electric vehicles as the research object. Through market research, it analyzes users' needs for micro electric vehicles from three perspectives, such as styling style design, color design, and performance demand design, and determines the design plan. After designing the preliminary model of the electric vehicle, the satisfaction of 50 users in experiencing the mini electric vehicle was tested, and the results showed that the majority of users had a high degree of satisfaction and could be put into mass production. Later, the LMD algorithm is used to detect the damage degree of the miniature electric vehicle under the condition of door deformation. The experimental results prove that the miniature electric vehicle designed in this paper has good anti-collision performance.

With the development of globalisation, people's awareness of environmental protection is gradually increasing. The purpose of this article is to study how companies can avoid risks, improve market competitiveness, and expand their profits under the concept of green innovation. From the perspectives of competitive environment, risk aversion and supply chain innovation, this paper uses game theory to analyse the number of green supply chain companies and how companies can achieve green pricing and decision-making innovation, and compared the different sales models of retailers, manufacturers and middlemen. The results of the study are as follows: the green innovation model has increased the profits of retailers and manufacturers by 20.53%; and 34.09%, and the revenue increase rates of the three sales models are 31.43%, 39.39%, and 41.67%, respectively.

Consumption of green products has tended to increase in Vietnam in recent years along with economic development and people's awareness of environmental protection. This study analyzes factors affecting customers' intention to consume green products in Hanoi based on the theory of planned behavior. We conducted a survey of 580 customers using the convenient sampling method, then used Cronbach's alpha analysis, exploring factor analysis, ANOVA and multivariate regression to identify influencing factors. The results show that there are 6 factors that influence green product consumption behavior including environmental attitude, social influence, trust, environmental concern, green promotion and eco label, in which environmental attitude is the factor that has the strongest impact on behavior. Based on the results, the study provides some implications for promoting green consumption in Vietnam.

With the worsening of the global environment and the strengthening of people's awareness of environmental protection, the air pollution caused by the exhaust emissions of marine diesel engines has attracted extensive attention from the international community. Because the exhaust post-treatment technology does not need to be reformed for diesel engine, and the quality requirement of fuel is relatively low, domestic and foreign research and development institutions all attach great importance to the research of exhaust post-treatment technology. By analyzing the mechanism and main chemical reaction of SCR reaction, the overall design scheme of marine diesel engine exhaust intelligent emission reduction control system was completed in order to reduce the nitrogen oxides and solid particles in the exhaust of marine diesel engine. According to TierIII emission regulation and marine diesel engine exhaust, the hardware structure design and model selection of marine diesel engine exhaust intelligent emission control system are completed. In order to ensure that the emission of the control system can meet the requirements of nitrogen oxide conversion rate and ammonia gas escape quantity at the same time, the corresponding model prediction algorithm is designed in this paper. Through the analysis of experimental results, it is proved that the control system established in this paper can well meet the emission requirements of TierIII regulations. The research content of this paper can be applied in the field of shipping to meet the requirements of TierIII regulations and prepare for more stringent emission regulations.

Due to a combination of rapid consumption of fossil fuels such as coal and oil with gradual increase in people's awareness of environmental protection, the research for substitute resources has become a hot spot. Because of their abundant sources of raw materials, fast regeneration rate and low greenhouse gas emissions, biomass resources have drawn much attentions. Woody fiber is one of the richest renewable biomass on earth, in which lignin is the largest renewable aromatic compound resource, therefore possessing a very broad application prospect. Nowadays, a large number of reviews on lignin extraction methods have been written while there are few explorations on the mechanisms behind those methods. Thus, the principles of several typical lignin extraction methods were described in this article. These principles were explored with the hope to provide a reference for future development of lignin extraction.

In contemporary political debate and scientific considerations, the dominant view is that green transformation is a remedy for all the problems of the modern world. The standard of living in the world is increasing, but people's awareness of environmental protection is also increasing. In practice, however, it turns out that the introduction of green energy solutions to the market also poses various problems. The purpose of this discussion is to attempt to assess the environmental impact of green energy. The chapter presents issues related to the impact of green energy on environmental protection, both in terms of benefits and problems resulting from the widespread use of green technologies. The literature research suggests that every way of obtaining energy is not entirely environmentally friendly. However, the researchers agree that the benefits of green energy are much greater than the negative consequences, and the latter occurs mainly in the production, installation and disposal of energy devices. Low emissions of harmful gases to the atmosphere and no release of toxic pollutants into water reservoirs place renewable energy sources on the right side of environmental protection.

With the rapid development of the social economy, people's awareness of environmental protection is gradually increasing. This is because the probability of geographical disasters occurring in the country is also gradually increasing. People have also begun to pay attention to the prevention of geological disasters and the geological environment, because geological disasters can have a great impact on people's life safety at any time. Therefore, it is necessary to take corresponding preventive measures in advance for geological disasters. This article conducts a series of analyses on geological disasters and other related topics.

The Construction of Decision Model of Multi-channel Closed-loop Supply Chain Based on Big Data