Analysis Of Thermal Environment Research Articles

Correlation analysis of landscape patterns and urban thermal environment in Kunming based on a panel data model

With the development of urbanization, the spatial and temporal distribution characteristics of the urban landscape pattern play a decisive role in the intensity of the urban heat island (UHI) effect. A panel data model was constructed to study the relationship between the UHI effect and landscape pattern in Kunming from 1995 to 2020 at four different scales. The results indicate: (1) The landscape pattern of Kunming changed obviously with time, the artificial patch increased, the natural patch decreased, and the UHI effect became more and more obvious; (2) With an increase in scale, the number of influencing variables continues to grow, and the impact of artificial patches gradually intensifies; (3) The normalized difference water index (NDWI) has the greatest influence on the UHI, and the cooling effect is more obvious with the increase in scale. Unlike previous studies, the spatial configuration of the landscape in Kunming City had a stronger effect on the UHI effect than the landscape grouping and vegetation index; (4) This paper introduces the panel data model into the discussion of the UHI for the first time, providing a new method for better understanding the changing patterns of the urban thermal environment.

Numerical analysis of the subway tunnel thermal environment to predict the train-mounted condenser inlet temperature in the cold climate zone of China

Reasonable control of the subway tunnel thermal environment is the main objective of the ventilation system design, which is critical to the effectiveness of the train-mounted condenser. In this study, a numerical model utilizing the dynamic mesh technique is developed to investigate the subway tunnel thermal environmental characteristics in the cold climate zone of China. Full-scale field measurements are implemented to verify the model’s accuracy. According to the simulation results, the single Piston wind shaft (PWS) (outlet end) is the optimal ventilation system in the cold climate zone of China. The effects of tunnel wall temperature, passenger flow, and regeneration braking system (RBS) efficiency on the subway tunnel thermal environment are thoroughly analyzed, which shows that the tunnel wall temperature has the greatest effect on the air temperature rise of the subway interval tunnel, the passenger flow has the greatest effect on the air temperature rise of the subway station tunnel. In contrast, the RBS efficiency has the least effect on the maximum condenser inlet temperature. On this basis, the predictive model for the maximum and average condenser inlet temperature is proposed. The findings of this study provide a theoretical basis for temperature control in subway tunnels in the cold climate zone of China and contribute to the safe and energy-efficient operation of subway environmental control systems.

Simulation of metal fatigue crack analysis based on thermal environment numerical analysis in street metal sculpture design process

With the popularity of urban public art, metal materials are easily affected by environmental factors in practical applications, especially the influence of thermal environment on metal fatigue, which often leads to cracks in sculptures, affecting their service life and safety. Through the numerical analysis of thermal environment, the fatigue crack generation mechanism of street metal sculpture in the process of use is deeply discussed in order to provide theoretical support and practical guidance for sculpture design. The finite element analysis method is used to simulate the stress distribution of metal sculpture under different thermal conditions. By setting a variety of conditions such as ambient temperature and humidity, the corresponding thermodynamic model is established, and the fatigue properties of metal materials are evaluated comprehensively The numerical model is calibrated with experimental data to improve the accuracy of the simulation. It is found that the change of thermal environment significantly affects the internal stress distribution of metal sculpture, and then affects the generation of fatigue cracks. At high temperature, the fatigue limit of the material is reduced, which leads to more cracks. Under the condition of sudden temperature change, the stress concentration of the material is more obvious, and the fatigue life of the metal is significantly shortened.

Thermal environment analysis and parameters optimization of a novel hot-air phase change heating bed

Maintaining indoor heating consumes significant energy; personalized heating can reduce this consumption. Existing bed-based heating devices have drawbacks in terms of temperature distribution and susceptibility to weather influences. In this paper, a hot-air phase change heating bed (HAPCHB) is proposed, which can heat the indoor thermal environment during the day and the bedding thermal environment at night. The theoretical analysis and simulation model of the new heating bed is established, and the experimental platform for analyzing the thermal environment building effect is built, which verifies the accuracy of the numerical simulation results. The experimental and simulation results show that the thermal inertia of the envelope has a great influence on the room temperature, but has little influence on the bed board temperature under the experimental conditions. Both indoor and bed board temperatures can keep the lower limit of thermal comfort for 12 h continuously. With the increase of phase change material (PCM), the thermal performance of the system is enhanced and attenuated, and the thermal performance of PCM-1.4 scheme is better. The rate of indoor temperature drop is similar under three heating times, but the performance of room temperature and bed board temperature is better at 6 h and 8 h respectively. The research results provide basis and guidance for improving indoor heating effect by HAPCHB.

Indoor thermal energy optimization and 3D visualization based on ambient light sensing in the protection of historical architectural landscapes

While preserving cultural heritage, historic buildings also face the challenge of modern comfort and energy efficiency. Thermal energy optimization of indoor environment is an important means to improve living comfort and reduce energy consumption. Especially when protecting historical buildings, it is necessary to analyze how to carry out effective thermal energy management without affecting their appearance and structure. This paper discusses the optimization strategy of indoor thermal energy based on ambient light sensing technology, combined with 3D visualization to achieve the balance between energy conservation and comfort in historic buildings. Through the dynamic monitoring and analysis of indoor thermal environment, a feasible solution is provided for the protection and utilization of historical buildings. In this study, ambient light sensors were deployed in a historical building to monitor indoor light, temperature and humidity in real time. Through data collection and analysis, the main factors affecting indoor thermal environment are identified. 3D visualization technology is used to visualize the indoor heat energy distribution, and specific optimization suggestions are put forward. The research shows that the application of ambient light sensor significantly improves the monitoring accuracy of indoor heat energy, and the implementation of optimization measures reduces the indoor temperature fluctuation and energy consumption. The 3D visualization visually shows the thermal energy changes before and after optimization, providing a basis for managers to make decisions. Combined with 3D visualization technology, it not only enhances the comprehensibility of data, but also provides innovative ideas for the protection and rational use of historical buildings.

Remote-sensing-based Approach to Analysis of Thermal Environment for Island-type City

Remote-sensing-based Approach to Analysis of Thermal Environment for Island-type City

Spatiotemporal Evolution in the Thermal Environment and Impact Analysis of Drivers in the Beijing–Tianjin–Hebei Urban Agglomeration of China from 2000 to 2020

As urbanization advances, the issue of urban heat islands (UHIs) grows increasingly serious, with UHIs gradually transitioning into regional urban heat islands. There is still a lack of research on the evolution and drivers of the thermal environment in urban agglomerations; therefore, in this study, we used trend analysis methods and spatial statistical analysis tools to investigate these issues in the Beijing–Tianjin–Hebei (BTH) urban agglomeration. The results demonstrated the following: (1) The land surface temperature (LST) exhibited low fluctuation, while the relative land surface temperature (RLST) fluctuated significantly. In Zhangjiakou and Chengde, the LST and RLST evolution trends were complex, and the results differed between daytime and nighttime, as well as between the annual and seasonal scales. In other regions, the trends of LST and RLST evolution were more obvious. (2) During the daytime, the high UHI clusters centered on “BJ–TJ–LF” and “SJZ–XT–HD” formed gradually; during the nighttime, the high UHI clusters were mainly observed in built-up areas. The distribution range and direction of UHIs showed greater degrees of evolution during the daytime in summer. (3) The total UHI area showed an increasing trend, and the intensity of heat stress suffered by the BTH agglomeration was increasing. (4) In BTH and Hebei, aerosol optical depth, surface solar radiation, population density, and gross domestic product were the dominant factors influencing UHIs; moreover, in Beijing and Tianjin, all factors showed an basically equal impact. The methodology and findings of this study hold significant implications for guiding urban construction, optimizing urban structure, and improving urban thermal comfort in the BTH urban agglomeration.

Analysis of Urban Thermal Environment Improved by Blue-Green Spaces on the Landsat Data: A Case Study on Tianjin

China’s urbanization is characterized by rapid speed, large scale and high energy consumption, which causes a series of ecological problems. Among these problems, urban thermal environment is particularly prominent, and the most intuitive reflection is the heat island effect. It is of great significance to optimize the urban layout to give full play to the cooling effect of blue-green spaces for improving urban thermal environment. Compared with other methods, it is more extensive and feasible. However, the current research on urban thermal environment mostly focuses on revealing the driving effects of different land use, and lacks of in-depth discussions on blue-green spaces. Tianjin is located in the northeast of the North China Plain, and has a typical warm temperate sub-humid monsoon climate. This paper takes the six districts of Tianjin City as the research area, covering Heping District, Nankai District, Hongqiao District, Hebei District, Hexi District and Hedong District, with a total area of about 181.18 square kilometers. The typical climate and urbanization characteristics of Tianjin can provide reference for cities with the same characteristics. Firstly, this paper had adopted the Landsat changing scenario of the city gained during the periods of 2004, 2011 and 2017 to formulate the land surface temperature by Mono-window Algorithm, and divided the results into seven temperature zones by standard deviation classification method. In regard to blue-green spaces, this paper had identified Landsat satellite data by Maximum Likelihood Classifier, and classified land use into three categories: blue spaces, green spaces, and non-blue and green spaces. And, next, this paper had studied the correlation between the landscape pattern of blue-green spaces and urban thermal environment by Landscape Pattern Analysis, and used Moving-window Analysis to compare the relationship between thermal environment and blue-green spaces at different spatial scales. And so the research results prove that, the high-temperature regions of Tianjin has been expanding along with the expansion and agglomeration of the urban areas and across the river space restrictions, while the low-temperature regions of the city are mainly concentrated in the blue-green spaces, during the periods of 2004, 2011 and 2017. Furthermore, in the landscape pattern level, there is a significant negative correlation between patch perimeter index of blue-green spaces and land surface temperature, and a significant positive correlation between patch perimeter area ratio index of blue-green spaces and land surface temperature. In the multi-scale spatial pattern, the correlation between the Percent of Landscape of blue spaces patches and land surface temperature is the highest in the 1500 meters × 1500 meters sample, and the Percent of Landscape of green spaces patches and land surface temperature is the highest in the 300 meters × 300 meters sample. In addition, the improvement efficiency of thermal environment in blue spaces is higher. In the end, the optimization suggestions of adjusting the layout of blue-green spaces to effectively improve the urban thermal environment problem are proposed. By optimizing the blue-green space landscape patterns at the optimal scale, increasing the blue spaces in the northern high temperature range, widening and transforming the existing waterways, constructing riverside greenways and other strategies to effectively deal with the thermal environmental problems, improving the ecology and livability of the city. It is hoped to provide new ideas and references for the construction of ecological and livable city under the background of rapid urbanization. In the research process, due to the limitation of data sources, calculation methods and other factors, the relevant conclusion is still limited at the spatial scale. In the future research, the thermal environment and the pattern of blue-green spatial landscape at the fine scale will be studied.

Winter indoor thermal environment and livability analysis of traditional residential houses in northeast Sichuan, China

With the rapid development of the national economy, increasing attention has been given to the living environment in rural areas, especially indoor thermal and wind environments. This study conducted on-site measurements and questionnaire surveys during winter in the indoor environment of five villages in northeastern Sichuan. Eighty-nine traditional residences were selected to investigate their fundamental characteristics, indoor thermal environment, humidity conditions, and comfort levels. Questionnaires and comparative experiments were also conducted with natives and locals. This combination of objective data and subjective feedback provides a comprehensive perspective for assessing the indoor thermal environment. The results showed that when expressed as neutral temperature and humidity, the temperature difference was 2.36 °C, with little humidity difference. Residents exhibited higher tolerance towards the local thermal and humidity environment than nonlocal volunteers, who showed greater sensitivity to it. In addition, residents had a Predicted Mean Vote (PMV) value of −0.69 and a heat acceptance value of −1.78, while non-local volunteers had a PMV value of −0.76 and a heat acceptance value of −1.32. A detailed evaluation and analysis of the relationship between the indoor thermal environment and human comfort of local residential houses was carried out, providing technical guidance for energy conservation and thermal insulation of local buildings.

Experimental analysis of building envelope integrating phase change material and cool paint under a real environment in autumn

The application of phase change material (PCM) and cool paint (CP) to building envelope is one of the effective solutions to improve thermal comfort of passive buildings. Therefore, the thermal performance of buildings in Hefei, China in autumn is compared and analyzed by integrating PCM and CP into the building envelope. According to the comprehensive analysis of indoor thermal environment and the ability to maintain indoor thermal comfort, it is concluded that the combined application of PCM and CP is better than the application of PCM or CP alone. And the combination of PCM and CP laid on the south wall and roof respectively is the best. It is more suitable for commercial buildings, which can prolong indoor air temperature (Ti) in the thermal comfort zone for more than 10 h during the day. The combination of PCM and CP laid on the roof can prolong Ti in the thermal comfort zone for more than 8.05 h, which is more suitable for residential buildings. The purpose is to explore the best combination mode of residential and commercial buildings according to the characteristics of temperature change and building types (according to people's main use time) in the real environment.

Thermal Environment Analysis and Optimization for Large Space Buildings with Radiant Cooling Floors: A Case Study of Xianyang International Airport

Radiant cooling floors combined with ventilation systems have been widely applied in large space buildings. However, there has been a lack of research on system control strategies for their adaptation to weather changes. This study aimed to find control strategies for radiant cooling floors combined with displacement ventilation systems used in large space buildings in order to achieve energy conservation and environmental improvement. Supply air temperature and cooling surface temperature were determined to be the control variables. It was found that cooling capacity of the combined system and the comfort index, PMV (predicted mean vote), were linear in relation to the supply air temperature and cooling surface temperature. The linear equations regarding cooling capacity and PMV were established separately using environment data, and then the optimal region was determined. A case study on Terminal 3 of Xi’an Xianyang International Airport was conducted. The thermal environment was investigated through on-site measurements, questionnaires, and numerical simulations with CFD (computational fluid dynamics). It was found that supply air temperature and cooling surface temperature had a significant impact on PMV, and less impact on the cooling capacity. Therefore, it was determined that the supply air temperature should be altered first when the indoor temperature exceeds the upper limit, and then the cooling surface temperature should be changed if the indoor environment continues to overheat with the supply air temperature set to 18 °C. Thus, the supply air temperature was kept at 18 °C, and the floor surface temperature was set to be 22 °C on a high-temperature day. The average PMV was 0.87, and the cooling capacity of the combined system was 200 W/(m2·K), according to the CFD simulation. In addition, the surface heat transfer coefficient of the cooling floor was found to be 10.26 W/(m2·K). This research provides important references for the design and operational management of radiant cooling floors in large space buildings.

Spatio-temporal analysis of local thermal environment in waterfront blocks along the both sides of pearl river in Guangzhou, China

Urban water bodies play an important role in regulating the thermal environment in densely populated cities. Typical central urban areas along both sides of the Pearl River in Guangzhou are selected as study sites and have been divided into 25 local zones with different spatial morphology. Mobile surveys are performed on typical summer and winter days. After temporal correction processing, the spatial distribution patterns of air temperature (Ta) and relative humidity (RH) at different times along both sides of the Pearl River are obtained. The daily Ta in the waterfront blocks ranged from 31.5 °C to 39.4 °C during summer, and from 17.50 °C to 27.50 °C during winter. Daily RH ranged from 41.3% to 67.3% during summer and 48.2%–76.4% during winter. This study explored the effects of urban spatial morphology and river wind on the local thermal environment of the waterfront blocks. The results showed that the river wind can have cooling and humidifying effects, especially on the windward side of these waterfront zones. The spatial heterogeneity and spatial autocorrelation characteristics of the block-scale waterfront areas are discovered to be clustered in both seasons. This study contributes to the design and optimization of thermally friendly waterfront blocks.

Thermal Performance and Environmental Analysis of a Brick Based on Traditional Gypsum Plaster Reinforced with Date Palm fibres

Timchemt is a traditional plaster that has been used for a long time and until today in the construction of the Ksar of Ouargla through their facility of obtaining and realization. In addition to that, because of the use of industrial building materials, nature is carried out by the toxic gases that are produced in factories when these materials are manufactured. So to minimize these negative effects on our planet and to encourage the use of local materials from the Saharan region, we have studied this material to improve its characteristics and to replace the others, especially because it is natural and does not harm the environment. The main objective of this paper is the improvement of the thermal properties of gypsum plaster by mixing it with date palm fibres in order to be used in wall and ceiling mortars. The thermal conductivity, thermal diffusivity, and thermal effusivity of the studied samples were measured using a steady hot plate. The obtained results show that the increase in the mass fraction of date palm fibres resulted in a significant improvement consisting of a reduction of the material's thermal properties. This reduction was up to 36% for the thermal conductivity, 13% for the thermal diffusivity, 23% for the thermal effusivity, and 16% for the volumetric thermal capacity.

Numerical calculation and experimental analysis of thermal environment in industrialized aquaculture facilities.

With the increasing market demand for high-quality aquatic products, the application of industrialized aquaculture facilities may get more attention. In order to improve the poor performance of thermal insulation, the accuracy of the numerical model was verified in this study through actual measured data. The model verification results shown that the average relative errors of the measured and calculated values of indoor air temperature, water temperature and roof inner surface temperature in the industrialized aquaculture workshop is within 2.5%, it suggested that the numerical calculation results are accurate. Furthermore, the thermal environment and thermal insulation performance of industrialized aquaculture facilities in winter were conducted based on the numerical calculations. After optimized the thermophysical parameters of the workshop enclosure structure, we found that the water body temperature could reach 21°C (which was close to the breeding temperature of grouper (Epinephelinae). Therefore, the numerical calculation method was further used to analyze the energy consumption of aquaculture water in January of a typical year in this area by heating to three constant temperatures (22, 25, and 28°C). When the aquaculture water was heated to the three constant temperature states, it needed to consume 8.56×105, 1.02×106 and 1.22×106 MJ of energy respectively, which were equal to the amount of energy released by the complete combustion of 29.3, 35.1 and 41.8 t standard coal. Moreover, it is concluded that the artificial temperature increase in winter maintains the temperature in the range of 22~25°C to provide the highest heating efficiency. This conclusion can provide theoretical basis and application reference for industrialized aquaculture in winter.

Multi-scale analysis of surface thermal environment in relation to urban form: A case study of the Guangdong-Hong Kong-Macao Greater Bay Area

With the expansion of cities and urban agglomerations, the impact of urban form on the urban thermal environment exhibits notable scale variations. Moreover, the synergistic effect between land surface temperature (LST) and urban heat island intensity (UHII) in urban areas with strong spatial heterogeneity is unclear. Here we explored the spatiotemporal variations of LST and surface UHII (SUHII) over the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) that includes cities of various urban form settings manifested by the local climate zone (LCZ) at multi-scale. The results confirm the LST and LCZ data obtained can effectively capture detailed thermal environment and urban form characteristics for large urban agglomeration (i.e., GBA). Our findings revealed the interactions of LST and SUHII have significant scale disparities. Regionally, the LST and SUHII exhibited strong spatial correlation in built-up area, but showed opposite variation trend in natural areas. At the city scale, the consistency of LST and SUHII is weak in cities with higher vegetation coverage, while strong in cities with lower vegetation coverage. Locally, LST and SUHII exhibited varied interactions in different LCZs. Finally, we proposed corresponding planning recommendations oriented by thermal environment optimization and sustainable development for GBA based on the conclusions.

Multi-scale modeling and fast inference for thermal environment analysis of air-cooled data center

Both the thermal environment of a data center room and the internal thermal environment of a server are of great concern, but it is extremely difficult to build and solve full-scale computational fluid dynamics (CFD) simulation models from room scale to chip scale. In this paper, a multi-scale simulation method for data centers is proposed to achieve this aim by coupling room-level, rack-level, and server-level models. Simulations of the designed working conditions were carried out. The results showed that aisle containment systems improve the server's thermal environment, resulting in a drop in the maximum temperature of the server from 87.5 °C to 73.1 °C. A multi-scale model of the data center can be used to optimize system operation parameters conveniently and accurately. In this simulation, air conditioning parameters that contribute to energy savings with higher supply air temperatures and lower supply air volumes while guaranteeing safe server operation were determined. Moreover, fast and accurate prediction of chip temperature by radial basis function (RBF) networks has been proven to be feasible.

Simulation and analysis of wind and thermal environments in an office with window shutters

By designing an office with window shutters and setting different window sizes, the indoor wind and thermal environments were investigated at different heights. Opening windows improved the thermal conditions in the office, especially in high temperature rooms. Despite generation of high ventilation rates at many locations, the ventilation rates were good within the main areas. It appeared critical to supply air through opening of the windows. A novel simulation method was explored. Meanwhile, an appropriate numerical simulation scheme was chosen to evaluate the effects of various office structures on thermal comfort, which can thus provide an important reference for the office building design.

Field measurement and analysis of subway tunnel thermal environment in severe cold region

Recently, subways in China's severe cold regions have developed rapidly. Harbin, a typical city in a severe cold region, can reach the lowest outdoor temperature of −37.7 °C in winter, making the thermal environment of the underground tunnels a huge challenge. Due to the complexity of the subway environment, there are few long-term field measurements, and the research on entrance and exit lines is often neglected. In this study, the thermal environment of Harbin Metro Line 1/3 and the entrance and exit lines was measured and studied, the heat production of train operation and annual heat storage heat was calculated. The results show that climatic conditions, burial depth, operating phase of the tunnel, passenger flow, and driving interval have an impact on the thermal environment of the tunnel. The daily average temperature difference between the two ends of the entrance and exit lines reached a maximum of 27.4 °C in winter. The average air temperature of Line 1 in summer, transition season and winter were 4.0 °C, 1.0 °C and 2.5 °C higher than that of Line 3, and the heat generated per hour was 201 MJ–242 MJ higher than Line 3. Furthermore, the heat storage capacity of tunnels in severe cold region was significantly higher than that in hot summer and warm winter region, the maximum difference was 823 GJ. The monitoring data are useful for both analytical and numerical studies and this study provide a valuable reference for the construction and operation of subways in severe cold regions.

Evaluation of Thermal Comfort with and without Fill Using a Thermal Environment Analysis Method for Building Envelopes with Thermally Complex Geometry: A Case Study in Hokkaido, Japan

Recently, the number of buildings with curved surfaces has been increasing. Although these buildings are not complex from a design perspective, they are thermally complex from an environmental engineering perspective. Computational fluid dynamics (CFD) is a tool used in environmental engineering analysis that requires advanced analysis techniques. Its analysis load is high, making its use impractical in design. Therefore, a coupled analysis method was developed using the two-dimensional heat flow calculation tool Hygrabe, energy simulation, and CFD. Using this method, the environmental analysis of a building with fill in Hokkaido, Japan, was performed and the accuracy of the analysis was verified. The results of the coupled analysis model were used to evaluate thermal insulation performance. The high thermostability of the fill contributes to the high degree of freedom of the exterior skin and is highly useful for design. The results show that the thermal performance of the building envelope with and without fill did not change the insulation performance. The results for January 15 were below −3.0 °C for all insulation performance levels but higher than the outside air temperature during the night.

Optimization of Atrium Thermal Environment in Summer Based on DeST Platform

The indoor environment simulation and optimization of atrium buildings are a research hotspot in the field of architectural technology. This article presents linear atrium buildings as the research object, introduces DeST simulation technology into thermal environment analysis, and studies the dynamic conditions and typical day time, the atrium itself structure, the structure of the rooms around the atrium and the thermal environment of the atrium space and its adjacent rooms. In the research process, two modes of natural ventilation and air conditioning were considered, and the optimal atrium building structure parameters under different outdoor weather conditions were obtained. The research results show that in natural ventilation mode, the thermal comfort temperature is the best when the atrium’s aspect ratio is 1.71; when using the air-conditioning mode, the air conditioning load is the smallest when the atrium’s aspect ratio is 1.55. In summer, the thermal environment of the linear A-shaped atrium is better than the H-shaped atrium. When the atrium window hole position is about 0.9 ∼ 1.5 m, the thermal environment is comfortable and energy saving.