scholarly journals A study of improving thermal environment of external louver through establishment of test bed

2018 ◽  
Vol 7 (3.3) ◽  
pp. 373
Author(s):  
Sun Pil Kwon ◽  
Jae Jun Jung ◽  
Byoung Jo Jung
Keyword(s):  
Statistical Analysis ◽  
Solar Radiation ◽  
Thermal Effect ◽  
Thermal Load ◽  
Thermal Environment ◽  
Direct Solar Radiation ◽  
Maximum Temperature ◽  
Test Bed ◽  
Solar Insolation ◽  
Maximum Temperature Difference

Background/Objectives: To improve a thermal load by increasing internal thermal effect of a building from direct solar radiation through an increase of glass windows.Methods/Statistical analysis: Through the establishment of test beds of the same size, the data of temperature, humidity, solar insolation and PMV of each test bed with or without external louver are acquired to analyze thermal environmental with the simulation.Findings: For the analysis of thermal environment, the amount of energy consumption has been analyzed through the simulation and the data of temperature, humidity, solar insolation and PMV have been acquired for the analysis. With the simulation, about 20% energy saving has been confirmed and the daily averages of temperature and humidity between 8AM to 7PM have been calculated to calculate the maximum temperature difference to be 9.4℃. The solar insolation between 9AM and 7PM was 300W/m2 or below.Improvements/Applications: The improvement of thermal effect with an external louver has been confirmed. It may be applied to the louver system to improve building thermal environment, awning to control direct solar radiation, blind to improve uniformity of illumination intensity toward building during daytime, external blind and ceiling louver system. 

Potential of an air curtain system orientated to create non-uniform indoor thermal environment and save energy

2016 ◽  
Vol 26 (2) ◽  
pp. 152-165 ◽  
Author(s):  
Chong Shen ◽  
Xiaoliang Shao ◽  
Xianting Li
Keyword(s):  
Thermal Environment ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Coefficient Of Performance ◽  
Maximum Temperature ◽  
Building Energy Efficiency ◽  
Maximum Temperature Difference ◽  
Air Curtain ◽  
Discharge Velocity ◽  
Save Energy

Non-uniform indoor environment has shown its potential for building energy efficiency and improving indoor air quality compared with traditional uniform environment created by mixing ventilation. An air curtain was employed to create non-uniform thermal environment in this study. The performance of an optimal ventilation strategy between an air curtain and the background ventilation in a typical air-conditioned room was investigated numerically. The air curtain's effectiveness and coefficient of performance (COP) are proposed as evaluation indices for assessing the efficacy of air curtain for this usage. The numerical model was validated by experiments. The energy saving potential of an air curtain system for maintaining a thermal environment of a compartment was studied under different internal heat-source characteristics. The discharge velocity of the air curtain was optimized. The results show that the efficacy of an air curtain system to create a non-uniform thermal environment is high, where the maximum temperature difference between two sides of an air curtain could be as high as 7.4℃. Both the flow rate of the air curtain and background ventilation can be reduced to save energy. An air curtain is more efficient when the heat is concentrated mainly in the unoccupied room partition and the unoccupied zone contains external walls.

scholarly journals Outdoor Thermal Environments of Main Types of Urban Areas during Summer: A Field Study in Wuhan, China

2022 ◽  
Vol 14 (2) ◽  
pp. 952
Author(s):  
Kun Li ◽  
Xuefei Li ◽  
Keji Yao
Keyword(s):  
Temperature Difference ◽  
Urban Areas ◽  
Thermal Environment ◽  
Cooling Effect ◽  
Maximum Temperature ◽  
Water Evaporation ◽  
Heat Island ◽  
Maximum Temperature Difference ◽  
Thermal Environments ◽  
Island Effect

Under the influence of the urban heat island effect, the thermal environments of urban built-up areas are poor, leading to the loss of urban vitality and the extreme deterioration of thermal comfort. In this paper, the outdoor thermal environment in Wuhan’s main urban area is studied via the use of field measurements. From June to August in the years 2015 to 2017, 20 measurement points were selected for monitoring from 08:00 to 19:00 h, which were located in spaces such as residential areas, parklands, commercial streets, and college/university campuses. The measurements for the same types of land and different types of land use are analyzed. A comprehensive thermal environment index is used to quantitatively evaluate the overall situations of thermal environments. The results showed that the cooling effect of vegetation shading was stronger than the effect of water evaporation and the maximum temperature difference between the two cooling methods reached 6.1 °C. The cooling effect of the canopy shading of tall trees was stronger than the effect of grassland transpiration and the maximum temperature difference was 2.8 °C. The streets with higher aspect ratios might improve the ventilation, but the wind speeds remained low, which did not provide a strong cooling effect. This study helps urban planners understand the thermal environment of Wuhan or similar cities with hot summer and diversified urban areas, and puts forward suggestions to reduce the heat island effect from the aspect of building layout, green coverage, shading mode, and street aspect ratio, so as to establish sustainable cities that are climate adaptable and environmentally friendly.

scholarly journals Research of Thermal Effect of Cable-Stayed Bridge with a Separated Side-Box Steel-Concrete Composite Girder under Solar Radiation

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Han-hao Zhang ◽  
Pei-zhi Wang ◽  
Shuanhai He ◽  
Yuan Li ◽  
Ke-fan Chen ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Thermal Effect ◽  
Temperature Stress ◽  
Thermal Field ◽  
Element Model ◽  
Beam Element ◽  
Maximum Temperature ◽  
Cable Stayed Bridge ◽  
Composite Girder ◽  
Mixed Element

At present, there are few studies on the thermal effect of solar radiation on a separated double-sided box steel-concrete composite girder cable-stayed bridge. In this paper, the beam element and mixed element models are combined with the theory of transient heat transfer analysis and meteorology; this approach is adopted to carry out a thermodynamic analysis of a related bridge project. The calculation results of the thermal field and structural thermodynamic analysis of bridge sections show that, in terms of a separated double-sided box steel-concrete composite girder cable-stayed bridge, the thermal field distributions of the main girder and the pylons are extremely complex under conditions of solar radiation. Therefore, the real thermal field cannot be accurately described as a one-dimensional temperature gradient. The traditional beam element model cannot accurately simulate the temperature effect, and it will underestimate its thermal effect. The calculated temperature stress values of the mixed element model are quite different from those of the of beam element model. The mixed element model can precisely reflect the local thermal effect of each component in this system under solar radiation. Compared with the calculation results of the beam element model, the maximum temperature stress of the bridge deck in each section of the main girder is generally 20% larger; the maximum temperature stress levels of the steel-beam top and bottom plates are 14.7 MPa and 15.9 MPa larger, respectively. The maximum shear stress of the steel-concrete interface is 0.2 MPa larger. The research results of the temperature effect calculated by the mixed element have an important guiding significance for the design and maintenance of bridges.

scholarly journals Conceptual Design of an Energy System for High Altitude Airships Considering Thermal Effect

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4204
Author(s):  
Qiumin Dai ◽  
Daoming Xing ◽  
Xiande Fang ◽  
Yingjie Zhao
Keyword(s):  
High Altitude ◽  
Thermal Effect ◽  
Conceptual Design ◽  
Design Method ◽  
Energy System ◽  
Maximum Temperature ◽  
Solar Array ◽  
Maximum Temperature Difference ◽  
Power Characteristics ◽  
Long Endurance

High altitude airships possess tremendous potential for long-endurance spot hovering platforms for both commercial and strategic applications. The energy system, which is mainly made up of solar array and regenerative fuel cell, is the key component of a high altitude airship. The thermal effect is a major factor that affects the performance of the energy system of long endurance stratospheric vehicles. In this paper, a conceptual design method focusing on the thermal and power characteristics of an energy system for stratospheric airships is proposed. The effect of thermal behavior of solar array on the energy system is analyzed. An optimized case is obtained on the consideration of power supply, thermal behaviors of helium and solar array. Results show that the maximum temperature difference of the solar array may be reduced by about 20 K and the mass of payload can be improved by up to 5%.

Vegetation as a Material of Roof and City to Cool down the Temperature

2012 ◽  
Vol 461 ◽  
pp. 552-556 ◽  
Author(s):  
Chen Yi Sun ◽  
Kuei Peng Lee ◽  
Tzu Ping Lin ◽  
Soen Han Lee
Keyword(s):  
Green Space ◽  
Thermal Environment ◽  
Green Roof ◽  
Green Roofs ◽  
Green Spaces ◽  
Maximum Temperature ◽  
Environmental Benefit ◽  
Maximum Temperature Difference ◽  
Thermal Influence ◽  
Maximum Cool

A large amount of research has been published in Taiwan on the reduction of the urban temperature for different strategies. The most important strategy for reducing ambient temperature is increasing green roofs or green spaces in city. For analyzing the effect of the vegetation on the thermal environment, this paper collects temperature and humidity data from two building roofs, one park and two streets which are located within same area and tries to analyze the thermal influence of vegetation in study area. The result of this research shows that the maximum cool effect of green roof was -1.60 °C and the maximum temperature difference between park and street was -2.00 °C. Therefore, it can also provide useful data to governments for calculating the environmental benefit if they carry out a green space and green roof policy.

scholarly journals Effectiveness of an evaporative charcoal cooler for the postharvest preservation of tomatoes and kales

2020 ◽  
Vol 66 (No. 2) ◽  
pp. 66-71
Author(s):  
Erick K. Ronoh ◽  
Christopher L. Kanali ◽  
Samuel N. Ndirangu
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Low Cost ◽  
Maximum Temperature ◽  
Cooling Efficiency ◽  
Maximum Temperature Difference ◽  
Light Rain ◽  
Colour Changes ◽  
Storage Technologies ◽  
Microclimate Conditions

The preservation of fresh produce can provide rural households with better diets all-year round and income by reducing their deterioration. Promotion of low-cost temporary storage technologies requires evidence of their effectiveness to attain conducive conditions. Therefore, this study was conducted to assess the effectiveness of an evaporative charcoal cooler for the preservation of tomatoes and kales. The cooler microclimate and outdoor conditions were investigated by measuring the air temperature and relative humidity. During the study period, the maximum temperature difference between the cooler and the outdoors was found to be 9.2 °C while the maximum relative humidity difference was 36.8%. Due to the presence of light rain and, consequently, low solar radiation, the temperature and relative humidity differences were significantly reduced. Despite the light rain, the cooler still registered a maximum relative humidity of 83.5% and a maximum cooling efficiency of 91.5%. Overall, the cooler demonstrated promising results in terms of favourable microclimate conditions, the shelf-life and colour changes for tomatoes and kales.

scholarly journals Seasonal Variations of Daytime Land Surface Temperature and Their Underlying Drivers over Wuhan, China

2021 ◽  
Vol 13 (2) ◽  
pp. 323
Author(s):  
Liang Chen ◽  
Xuelei Wang ◽  
Xiaobin Cai ◽  
Chao Yang ◽  
Xiaorong Lu
Keyword(s):  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Rapid Urbanization ◽  
The Impact ◽  
The City

Rapid urbanization greatly alters land surface vegetation cover and heat distribution, leading to the development of the urban heat island (UHI) effect and seriously affecting the healthy development of cities and the comfort of living. As an indicator of urban health and livability, monitoring the distribution of land surface temperature (LST) and discovering its main impacting factors are receiving increasing attention in the effort to develop cities more sustainably. In this study, we analyzed the spatial distribution patterns of LST of the city of Wuhan, China, from 2013 to 2019. We detected hot and cold poles in four seasons through clustering and outlier analysis (based on Anselin local Moran’s I) of LST. Furthermore, we introduced the geographical detector model to quantify the impact of six physical and socio-economic factors, including the digital elevation model (DEM), index-based built-up index (IBI), modified normalized difference water index (MNDWI), normalized difference vegetation index (NDVI), population, and Gross Domestic Product (GDP) on the LST distribution of Wuhan. Finally, to identify the influence of land cover on temperature, the LST of croplands, woodlands, grasslands, and built-up areas was analyzed. The results showed that low temperatures are mainly distributed over water and woodland areas, followed by grasslands; high temperatures are mainly concentrated over built-up areas. The maximum temperature difference between land covers occurs in spring and summer, while this difference can be ignored in winter. MNDWI, IBI, and NDVI are the key driving factors of the thermal values change in Wuhan, especially of their interaction. We found that the temperature of water area and urban green space (woodlands and grasslands) tends to be 5.4 °C and 2.6 °C lower than that of built-up areas. Our research results can contribute to the urban planning and urban greening of Wuhan and promote the healthy and sustainable development of the city.

scholarly journals The role of L/W in the solar radiation for Saharian cities

2019 ◽  
Vol 91 ◽  
pp. 05006
Author(s):  
Rami Qaoud ◽  
Alkama Djamal
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Energy Levels ◽  
Direct Solar Radiation ◽  
Test Field ◽  
Natural Lighting ◽  
The Difference ◽  
The Impact ◽  
The Relationship

The urban fabric of the desert cities is based on the principle of reducing the impact of urban canyons on direct solar radiation. Here comes this research, which is based on a comparative study of the periods of direct solarisation and values of the solar energy of urban canyons via two urban fabrics that have different building densities, where the ratio between L/W is different. In order to obtain the real values of the solar energy (thermal, lighting), the test field was examined every two hours, each three consecutive days. The measurement stations are positioned by the three types of the relationship between L/W, (L≥2w, L=w, L≤0.5w). According to the results, we noticed and recorded the difference in the periods of direct solarization between the types of urban engineering canyons, reaching 6 hours a day, the difference in thermal values of air, reaching 4 °C, and the difference in periods of direct natural lighting, reaching 6 hours. It should be noted that the role of the relationship between L/W is to protect the urban canyons by reducing the impact of direct solar radiation on urban canyons, providing longer hours of shading, and reducing solar energy levels (thermal, lighting) at the urban canyons. This research is classified under the research axis (the studies of external spaces in the urban environment according to the bioclimatic approach and geographic approach). But this research aims to focus on the tracking and studying the distribution of the solar radiation - thermal radiation and lighting radiation - in different types of street canyons by comparing the study of the direct solarization periods of each type and the quantity of solar energy collected during the solarization periods.

Dynamic Modeling of Solar Radiation Disturbances Based on a Biomimetic Cloud Shading Model

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Jesús García ◽  
Iván Portnoy ◽  
Ricardo Vasquez Padilla ◽  
Marco E. Sanjuan
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
Control Strategies ◽  
Ground Level ◽  
Direct Solar Radiation ◽  
Complex Phenomenon ◽  
Two Dimensional ◽  
Multi Objective Optimization ◽  
Tuning Parameters ◽  
Radiation Time

Variation in direct solar radiation is one of the main disturbances that any solar system must handle to maintain efficiency at acceptable levels. As known, solar radiation profiles change due to earth's movements. Even though this change is not manipulable, its behavior is predictable. However, at ground level, direct solar radiation mainly varies due to the effect of clouds, which is a complex phenomenon not easily predictable. In this paper, dynamic solar radiation time series in a two-dimensional (2D) spatial domain are obtained using a biomimetic cloud-shading model. The model is tuned and compared against available measurement time series. The procedure uses an objective function based on statistical indexes that allow extracting the most important characteristics of an actual set of curves. Then, a multi-objective optimization algorithm finds the tuning parameters of the model that better fit data. The results showed that it is possible to obtain responses similar to real direct solar radiation transients using the biomimetic model, which is useful for other studies such as testing control strategies in solar thermal plants.

Effects of Natural Gas Compositions on Engine In-Cylinder Process

2015 ◽  
Vol 1092-1093 ◽  
pp. 498-503
Author(s):  
La Xiang ◽  
Yu Ding
Keyword(s):  
Natural Gas ◽  
Alternative Fuels ◽  
Combustion Process ◽  
Engine Performance ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Test Bed ◽  
Promising Alternative ◽  
Natural Gas Engines ◽  
Lower Maximum

Natural gas (NG) is one of the most promising alternative fuels of diesel and petrol because of its economics and environmental protection. Generally the NG engine share the similar structure profile with diesel or petrol engine but the combustion characteristics of NG is varied from the fuels, so the investigation of NG engine combustion process receive more attentions from the researchers. In this paper, a zero-dimensional model on the basis of Vibe function is built in the MATLAB/SIMULINK environment. The model provides the prediction of combustion process in natural gas engines, which has been verified by the experimental data in the NG test bed. Furthermore, the influence of NG composition on engine performance is investigated, in which the in-cylinder maximum pressure and temperature and mean indicated pressure are compared using different type NG. It is shown in the results that NG with higher composition of methane results in lower maximum temperature and mean indicated pressure as well as higher maximum pressure.

Sign in / Sign up

Export Citation Format

Share Document