Measurement of indoor environmental parameters and analysis of the condensation phenomenon in urban utility tunnels

2022 ◽  
pp. 1420326X2110564
Author(s):  
Chuanmin Tai ◽  
Guansan Tian ◽  
Wenjun Lei
Keyword(s):  
Water Supply ◽  
Surface Temperature ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Environmental Parameters ◽  
Dew Point ◽  
Control Mode ◽  
Safe Management ◽  
Environmental Test ◽  
Water Supply Pipeline

Condensation is a major issue in the safe operation of utility tunnels. To address the condensation problem, the indoor air temperature, relative humidity (RH) and surface temperature in an urban utility tunnel in Jining were continuously measured, and the condensation conditions were surveyed and analysed. The results indicated that under natural ventilation conditions, the air temperature in the comprehensive cabin varied from 23.4°C to 24.5°C, the RH fluctuated between 86.4% and 95.3%, and the corresponding air dew point temperature (DPT) remained in the range of 22.2°C–22.9°C. The surface temperature of the water supply pipeline ranged from 17.8°C to 18.5°C, which was far lower than the DPT in the tunnel, resulting in serious condensation. A water supply pipeline with an anti-condensation design was developed based on environmental test data. A 25-mm-thick rubber plastic sponge insulation layer was used to thermally insulate the water supply pipeline, preventing further dew condensation. Furthermore, mechanical ventilation had little effect on reducing the RH in the tunnel and may actually cause dew condensation; therefore, a ventilation control mode was proposed in this study. These results are expected to provide basic data for further research and reference for the safe management of utility tunnels.

Modelling pavement temperature for winter maintenance operations

2004 ◽  
Vol 31 (2) ◽  
pp. 369-378 ◽  
Author(s):  
Aly Sherif ◽  
Yasser Hassan
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Negative Impact ◽  
Weather Conditions ◽  
Statistical Modelling ◽  
Dew Point ◽  
Road Maintenance ◽  
Winter Maintenance ◽  
Pavement Surface ◽  
Pavement Temperature

Road and highway maintenance is vital for the safety of citizens and for enabling emergency and security services to perform their essential functions. Accumulation of snow and (or) ice on the pavement surface during the wintertime substantially increases the risk of road crashes and can have negative impact on the economy of the region. Recently, road maintenance engineers have used pavement surface temperature as a guide to the application of deicers. Stations for road weather information systems (RWIS) have been installed across Europe and North America to collect data that can be used to predict weather conditions such as air temperature. Modelling pavement surface temperature as a function of such weather conditions (air temperature, dew point, relative humidity, and wind speed) can provide an additional component that is essential for winter maintenance operations. This paper uses data collected by RWIS stations at the City of Ottawa to device a procedure that maximizes the use of a data batch containing complete, partially complete, and unusable data and to study the relationship between the pavement surface temperature and weather variables. Statistical models were developed, where stepwise regression was first applied to eliminate those variables whose estimated coefficients are not statistically significant. The remaining variables were further examined according to their contribution to the criterion of best fit and their physical relationships to each other to eliminate multicollinearities. The models were further corrected for the autocorrelation in their error structures. The final version of the developed models may then be used as a part of the decision-making process for winter maintenance operations.Key words: winter maintenance, pavement temperature, statistical modelling, RWIS.

Applicable Correlations Based on Field Survey and Theory for Predicting the Indoor Thermal Climate

2012 ◽  
Vol 610-613 ◽  
pp. 2819-2822
Author(s):  
Fen E Hu ◽  
Fan Wang ◽  
Neng Bang Hou ◽  
Fei Xiang Chen
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Sensation ◽  
Environmental Parameters ◽  
Newton’S Iterative Method ◽  
Diffuse Solar Radiation ◽  
Thermal Climate ◽  
One Year ◽  
Radiant Temperature

Fanger’s PMV is the most famous thermal sensation index but it is too complex to be applied in practice. Besides, the PMV index does not take into account the effect of the hourly beam and diffuse solar radiation absorbed by the room on the indoor thermal climate. In order to obtain applicable correlations with consideration of solar radiation, a one-year measurement has been carried out in a naturally ventilated residential room in Qujing Normal University of Yunnan province, China. Based on collected data, PMV indices are calculated by using Newton’s iterative method. The correlations of the PMV and the environmental parameters — outdoor air temperature, indoor mean air temperature, mean radiant temperature, wind velocity, relative humidity, and hourly beam and diffuse solar radiation — have been studied by using the multivariable regression techniques. Lots of correlations with high correlativity have been developed in this paper. It is convenient to use these results to predict the indoor thermal climate in the natural ventilation buildings in the subtropical plateau monsoon climate.

Air Environment and Energy Performance of a Building Courtyard in the Heating Season

2014 ◽  
Vol 501-504 ◽  
pp. 2231-2239
Author(s):  
Ning Bo Zhang ◽  
Yan Ming Kang ◽  
Ke Zhong ◽  
Jia Ping Liu
Keyword(s):  
Air Temperature ◽  
Natural Ventilation ◽  
Environmental Parameters ◽  
Ambient Air ◽  
Energy Performance ◽  
Building Envelope ◽  
Air Infiltration ◽  
Central Air Conditioning ◽  
Pollutant Source ◽  
New Buildings

Courtyards are now used in many new buildings in China for taking advantage of better natural ventilation and thus improving the microclimate. However, when the building is equipped with a central air-conditioning (AC) system for space heating in winter, the warm air infiltration from the heated rooms enters into the courtyard and leads to changes in the natural ventilation characteristics in the courtyard. In the present study, the air environment and energy performance of a courtyard style office building in Shanghai were monitored in winter. The internal and external environmental parameters such as air temperature, CO2and particle concentrations were measured simultaneously and continuously when the building was heated or was not in use. The results show that when there is no apparent pollutant source in the courtyard, a better microenvironment can be established and the air quality in the space is almost the same as the ambient air, because its natural ventilation is enhanced by the warm air infiltration from the heated rooms. Compared to a building without a courtyard, the building envelope heat loss can be reduced by 20% or 11% in winter for buildings with or without a corridor facing the courtyard enclosed by glass windows, respectively, due to the warm air infiltration which increases the air temperature in the courtyard.

Study on Evaluation Index of Cold Insulation Performance

2012 ◽  
Vol 516-517 ◽  
pp. 1201-1204
Author(s):  
Hai Qian Zhao ◽  
Zhong Hua Wang ◽  
Xiao Yan Liu ◽  
Zhi Guo Wang
Keyword(s):  
Surface Temperature ◽  
Outer Surface ◽  
Environmental Parameters ◽  
Dew Point ◽  
Evaluation Index ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Two Temperatures ◽  
The Relationship ◽  
Insulation Performance

The outer surface temperature of cold insulation structure must be higher than air dew point temperature is stipulated in national standard.But the outer surface temperature of cold insulation structure and air dew point temperature normally wave in a certain range with the change of environmental parameters. In Practical application, it is difficult to determine the relationship between these two temperatures. Functional relationship between the outer temperature, air dew point temperature and environmental temperature or humidity is fitted.The influence of the air temperature and humidity is analyzed. Some suggestions about design and evaluation index of cold insulation are offered based on this research.

scholarly journals Changes in Temperature and Moisture Content of an Extensive-Type Green Roof

2019 ◽  
Vol 11 (9) ◽  
pp. 2498 ◽  
Author(s):  
Anna Baryła ◽  
Tomasz Gnatowski ◽  
Agnieszka Karczmarczyk ◽  
Jan Szatyłowicz
Keyword(s):  
Moisture Content ◽  
Surface Temperature ◽  
Air Temperature ◽  
Green Roof ◽  
Atmospheric Precipitation ◽  
Environmental Parameters ◽  
Green Roofs ◽  
Imaging Camera ◽  
Daily Changes ◽  
Continental Climate

Green roofs ought to be perceived as ensuring a wide-ranging contribution to the sustainable urban environment. The aim of the study was; (1) to investigate and analyse the differences in the surface temperature between four models of green roofs of the extensive type and a conventional roof (covered with bitumen) under the conditions of a continental climate; (2) to assess the influence of environmental parameters (climatic water balance, air temperature, relative humidity, moisture content in the profile) on changes in the temperature of the extensive type green roof profile (substrate and vegetation mat). The study (1) was carried out during the period of June–December 2016 using a thermal imaging camera. As a result, the greatest differences in temperature were noted in June and July, with a maximum difference between the temporary surface temperature of a green roof and a conventional roof of up to 24 °C. The (2) study was conducted on a green roof profile with sedum plant vegetation. The measured parameters were: the temperature of the surface, the temperature and humidity at depths of 3 cm and 15 cm, and active radiation in the photosynthesis process (PAR). As the result, the range of daily changes in the surface temperatures and the vegetation mat were higher than the range of changes in the air temperature. Atmospheric precipitation decreased the thermal gradient in the soil, as well as the temperature fluctuations in the course of a day as a result of the increase in humidity following a rainfall. During the summer period, over the course of a day, the surface temperature was 5 °C higher than the air temperature. The largest correlation was obtained between the air temperature and the temperature of the surface as well as the temperature of the structural layers.

New Correlations Including Hourly Horizontal Radiation for Predicting Indoor Thermal Environment

2011 ◽  
Vol 71-78 ◽  
pp. 2671-2674
Author(s):  
Sheng Xian Wei ◽  
Shi Mei Guo ◽  
Xi Jia He
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Environmental Parameters ◽  
Newton’S Iterative Method ◽  
Indoor Thermal Environment ◽  
One Year ◽  
Radiant Temperature

Fanger’s PMV is the most famous thermal sensation index but it is too complex to be applied in practice. Besides, the PMV index does not include the effect of horizontal solar radiation on the indoor thermal environment. In order to obtain simple and applicable correlations with consideration of solar radiation, a one-year measurement has been conducted in a naturally ventilated residential room in Qujing Normal University of Yunnan province, China. Based on collected data, PMV indices are calculated by using Newton’s iterative method. The relationships of the PMV and the environmental parameters — outdoor air temperature, indoor mean air temperature, mean radiant temperature, wind velocity, relative humidity, and hourly horizontal solar radiation — have been studied by the multivariable regression techniques. Large numbers of correlations with high correlativity have been developed in the present paper. It is convenient to use them to evaluate and predict the indoor thermal environment in the natural ventilation buildings.

scholarly journals Moisture content of cereals at harvesting time by comparing microclimate values and standard weather data

1993 ◽  
Vol 41 (3) ◽  
pp. 167-178
Author(s):  
A.J. Atzema
Keyword(s):  
Moisture Content ◽  
Surface Temperature ◽  
Air Temperature ◽  
Weather Conditions ◽  
Dew Point ◽  
Weather Data ◽  
Daily Cycle ◽  
The Difference ◽  
High Equilibrium ◽  
Screen House

The moisture content of wheat and barley together with the weather elements were measured at 3 different experimental sites in the Netherlands in 1990-91. The difference in the dew point temperature in the screen[house] and in the field was small. However, the differences between air temperature in the screen and those at different heights in wheat and in barley stands were considerable. In daytime the surface temperature of barley was higher than that of wheat under the same weather conditions as a result of a higher absorbtion coefficient. Both for wheat and barley, the maximum difference between the calculated moisture content was 0.5%, using the air temperature at 1.5 m height from the nearest standard weather station and the surface temperature of the spikes. Barley had a greater daily cycle in the moisture content of the grains than wheat as a result of a high equilibrium moisture content during the night and a low one in daytime.

Effects of Ambient Air Relative Humidity and Surface Temperature on Water Droplet Spreading Dynamics

2018 ◽  
Author(s):  
M. Jadidi ◽  
M. A. Farzad ◽  
J. Y. Trepanier ◽  
A. Dolatabadi
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Surface Temperature ◽  
Air Temperature ◽  
Water Droplet ◽  
Superhydrophobic Surface ◽  
High Speed ◽  
Ambient Air ◽  
Dew Point ◽  
Droplet Spreading

Water droplet impact on horizontal glass, aluminum, and superhydrophobic surfaces is experimentally investigated using high speed imaging. Experiments are performed at three different relative humidities (i.e. 10, 20 and 30%) and three surface temperatures (i.e. 20, 2 and −2°C) to ascertain their effects on droplet spreading and recoil behaviors. In this study, the droplet Weber number, Reynolds number, and the ambient air temperature are fixed at 16.2, 1687, and 23°C, respectively. The high-speed images of impact, spreading and recoil of the droplets as well as the temporal variations of droplet spreads are prepared. Results show that the ratio of surface temperature to dew point temperature (which depends on the air temperature and relative humidity) has a significant influence on droplet spreading, recoil, and contact angle. When this ratio is less than one, condensation and frost formation become important. Decreasing the mentioned ratio (it can be done by decreasing the surface temperature or increasing the relative humidity) causes the droplet spreading factor for hydrophilic surfaces to increase significantly. For superhydrophobic surface, decreasing this ratio (within the mentioned range) does not influence the maximum spreading. However, the recoiling phase is slowed down and the droplet detachment time form the superhydrophobic surface is increased noticeably. In addition, the equilibrium contact angle decreases as the mentioned ratio decreases.

The Numerical Simulation of Thermal Environment of Strawberry Greenhouse in Natural Ventilation

2014 ◽  
Vol 501-504 ◽  
pp. 2276-2281 ◽  
Author(s):  
Wei Hong Fu ◽  
Shi Jun You
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Environmental Parameters ◽  
Outdoor Air ◽  
Air Velocity ◽  
Indoor Thermal Environment ◽  
Average Temperature

The method of numerical simulation was adopted in this study to explore the size of the natural ventilation inlet opening, outdoor temperature and ambient wind speed and other environmental parameters to effect of the varied rules of thermal environment of the strawberry solar greenhouse. The variation of outdoor air temperature effected greatly to the indoor thermal environment, the average air velocity in the strawberry growing zoon within the greenhouse was rose initially and dropped tend to the steady with increasing outdoor air temperature. The average temperature in the strawberry growing zoon was decreased with increasing the outside wind speed. The average air velocity was increased gradually in the strawberry growing zoon within the greenhouse with increasing outdoor wind speed. The average velocity was reduced gradually toward to constant.

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