Theoretical predictions and field measurements for potential natural ventilation in urban vehicular tunnels with roof openings

2014 ◽  
Vol 82 ◽  
pp. 450-458 ◽  
Author(s):  
Yan Tong ◽  
Xin Wang ◽  
John Zhai ◽  
Xiaofeng Niu ◽  
LinLin Liu
Keyword(s):  
Natural Ventilation ◽  
Field Measurements ◽  
Theoretical Predictions

The Peak Overpressure Field Resulting From Shocks Emerging From Circular Shock Tubes

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
A. J. Newman ◽  
J. C. Mollendorf
Keyword(s):  
Shock Tube ◽  
Horizontal Plane ◽  
Three Dimensional ◽  
Polar Angle ◽  
Field Measurements ◽  
Initial Development ◽  
Theoretical Predictions ◽  
Mach Numbers ◽  
Tube Exit ◽  
Semi Empirical

A simple semi-empirical model for predicting the peak overpressure field that results when a shock emerges from a circular shock tube is presented and validated. By assuming that the shape of the expanding shock remains geometrically similar after an initial development period, an equation that describes the peak overpressure field in the horizontal plane containing the shock tube’s centerline was developed. The accuracy of this equation was evaluated experimentally by collecting peak overpressure field measurements along radials from the shock tube exit at 0 deg, 45 deg, and 90 deg over a range of shock Mach numbers from 1.15 to 1.45. It was found that the equation became more accurate at higher Mach numbers with percent differences between experimental measurements and theoretical predictions ranging from 1.1% to 3.6% over the range of Mach numbers considered. (1) Shocks do propagate in a geometrically similar manner after some initial development length over the range of Mach numbers considered here. (2) The model developed here gives reasonable predictions for the overpressure field from a shock emerging from a circular shock tube. (3) Shocks are expected to be completely symmetric with respect to the shock tube’s centerline, and hence, a three dimensional overpressure field may be predicted by the model developed here. (4) While there is a range of polar angle at which the shock shape may be described as being spherical with respect to the shock tube’s exit, this range does not encompass the entirety of the half space in front of the shock tube, and the model developed here is needed to accurately describe the entire peak overpressure field.

Local Natural Ventilation Registration while Ensuring Aerological Safety at the Mining Enterprises

2021 ◽  
pp. 60-65
Author(s):  
S.S. Kobylkin ◽  
◽  
V.M. Khubieva ◽  
Keyword(s):  
Calculation Method ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Field Measurements ◽  
Industrial Safety ◽  
Ventilation Network ◽  
Negative Consequences ◽  
Practical Application ◽  
Mining Operations ◽  
Mine Workings

Safety of mining operations is the basis for the efficient functioning of the mines. During mining operations, due to changing conditions in the mine workings, the natural draft began to appear more frequent. Moreover, its influence can be limited to a separate section without affecting the entire ventilation network. In this paper, the new concept is introduced and explained — local natural ventilation. The classification signs and the negative consequences of its manifestation are presented. Main difference between the local natural ventilation as a subspecies of natural ventilation as a whole lies in the limited action both in the spaces of mine workings or individual sections, and in time. Particularly its occurrence depends on the season or the technological processes performed. In this case, the local natural ventilation is not an emergency and is not subject to registration as an incident or accident. However, its manifestations can lead to both incidents and accidents. Taking this factor into account will allow to increase the level of aerological safety at the mining enterprises. A method of three-dimensional computer modeling is proposed for predicting the manifestation of local natural ventilation and making decisions to prevent it. An example of the use of this approach at the Norilsk mine during the construction of shafts with verification of field measurements is given. It confirms the possibility of practical application of the proposed calculation method. The algorithm for registering the local natural ventilation considered in the article makes it possible to develop activities for improving the level of industrial safety at the mining enterprises as a whole.

scholarly journals The Effects of Courtyards on the Thermal Performance of a Vernacular House in a Hot-Summer and Cold-Winter Climate

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1042 ◽  
Author(s):  
Shimeng Hao ◽  
Changming Yu ◽  
Yuejia Xu ◽  
Yehao Song
Keyword(s):  
Solar Radiation ◽  
Thermal Performance ◽  
Natural Ventilation ◽  
Field Measurements ◽  
Ground Level ◽  
Active Role ◽  
Thermal Mass ◽  
Cold Winter ◽  
Winter Climate ◽  
Climate Zones

Achieving comfort in hot summer and cold winter (HSCW) climate zones can be challenging, since the climate is characterized by high temperatures in the summer and relatively colder temperatures in the winter. Courtyards, along with other semi-open spaces such as verandas and overhangs, play an important role in mitigating outdoor climate fluctuations. In this research, the effects of courtyards on the thermal performance of vernacular houses in HSCW climate zones were studied via field measurements and computational fluid dynamics (CFD) models. The selected courtyard house was a representative vernacular timber dwelling situated in the southeast of Chongqing, China. The indoor and outdoor air temperature measurements revealed that the courtyard did play an active role as a climatic buffer and significantly reduced the temperature’s peak value in the summer, while during the winter, the courtyard prevented the surrounding rooms from receiving direct solar radiation, and thus to some extent acted as a heat barrier. The contributions of thermal mass are quite limited in this area, due to insufficient solar radiation in winter and general building operations. The natural ventilation mechanism of courtyard houses in HSCW zones was further studied through CFD simulations. The selected opened courtyard was compared to an enclosed structure with similar building configurations. The airflow patterns driven by wind and buoyancy effects were first simulated separately, and then together, to illustrate the ventilation mechanisms. The simulation results show that the courtyard’s natural ventilation behavior benefited from the proper openings on ground level.

scholarly journals KONDISI TERMAL PADA PENGHAWAAN ALAMI DI RUANG TUNGGU UTAMA STASIUN SEMARANG TAWANG

2018 ◽  
Vol 2 (3) ◽  
pp. 144
Author(s):  
Hana Faza Surya Rusyda ◽  
Erni Setyowati ◽  
Gagoek Hardiman
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Research Method ◽  
Thermal Condition ◽  
Natural Ventilation ◽  
Thermal Conditions ◽  
Field Measurements ◽  
Waiting Room ◽  
Train Station ◽  
State Of Mind

Abstract:. Thermal comfort is a state of mind that expresses a user's satisfaction with thermal conditions. This study focuses on the design of natural ventilation which is one of the efforts to reduce the heat that exists in the building, especially in maintaining the thermal conditions. Tawang Train Station, Semarang has a natural ventilation design that is still maintained especially in the waiting room. This study aims to determine the thermal conditions of the design of ventilation using the theory of Mom and Wiseborn, SNI 03-6572-2001, and Olgyay chart. This research method uses quantitative and field measurements were done for 14 hours to know the movement of air, temperature, humidity. The results were then compared with the standard and the theory. It was found that thermal comfort conditions that still utilize the movement of the wind from natural ventilation in the main waiting room of Tawang Semarang Station.Keyword: Thermal Condition, Natural Ventilation, Semarang Tawang Station.Abstrak: Kenyamanan termal merupakan suatu kondisi pikir seseorang yang mengekspresikan kepuasan pengguna terhadap kondisi termal.  Penelitian ini berfokus pada desain penghawaan yang merupakan salah satu upaya mengurangi panas yang ada dalam bangunan terutama dalam menjaga kondisi termal. Stasiun Tawang Semarang, mempunyai desain penghawaan alami yang masih dipertahannkan terutama pada ruang tungguya. Penelitian ini  bertujuan untuk mengetahui kondisi termal dari desain penghawaan dengan menggunakan teori mom dan wiseborn, SNI 03-6572-2001, serta grafik olgyay. Metode penelitian ini menggunakan kuantitatif dan pengukuran dilapangan dilakukan selama 14 jam untuk mengetahui pergerakan udara, temperature, kelembaban. Hasil penelitian kemudian di bandingkan dengan standar SNI, Mom & Wiseborn dan Diagram Olgyay. Ditemukan bahwa kondisi kenyamanan termal yang masih memanfaatkan pergerakan angin dari ventilasi alami pada ruang tunggu utama Stasiun Semarang Tawang.Kata Kunci: Kondisi Termal, Ventilasi Alami, Ruang tunggu, Stasiun Semarang Tawang

scholarly journals Can Underground Buildings Be Beneficial in Hot Regions? An Investigation of Field Measurements in On-Site Built Underground Construction

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 341
Author(s):  
Mamdooh Alwetaishi ◽  
Omrane Benjeddou ◽  
Ashraf Balabel ◽  
Ali Alzaed
Keyword(s):  
Natural Ventilation ◽  
Negative Impact ◽  
Field Measurements ◽  
Energy Simulation ◽  
Shopping Malls ◽  
Underground Construction ◽  
Indoor Temperature ◽  
Building Heat ◽  
The Impact ◽  
Underground Constructions

Globally, there has been a remarkable growth in the number of underground constructions (UGC) such as railways, offices, hospitals and shopping malls. This expansion is a result of urban area extensions that are limited by the availability of buildable land. Underground construction can also be used to protect people from the harshness of the outdoor conditions. The aim of this research is to investigate the impact of underground construction in hot regions. The major issue with most of the current UGC is the lack of natural ventilation and daylight. This has a clear negative impact on the user’s perception and comfort. The new design elevates the external walls to place some of the windows above ground for the purpose of natural ventilation and providing a view. The study conducted an experiment using an underground room enhanced with field measurements to ascertain the indoor temperature as well as relative humidity. In addition, the study used an energy simulation to calculate building heat transfer and solar heat gain. It was revealed that the use of UGC in hot regions promoted with the addition of natural ventilation can lower the indoor temperature by 3 °C in summer.

scholarly journals Modeling and Validation of the Cool Summer Microclimate Formed by Passive Cooling Elements in a Semi-Outdoor Building Space

2020 ◽  
Vol 12 (13) ◽  
pp. 5360
Author(s):  
Maria Alejandra Del Rio ◽  
Takashi Asawa ◽  
Yukari Hirayama
Keyword(s):  
Natural Ventilation ◽  
Cfd Simulation ◽  
Field Measurements ◽  
Modeling Method ◽  
Passive Cooling ◽  
Indoor Space ◽  
Effective Combination ◽  
Cool Summer ◽  
Cooling Element ◽  
Del Rio

Previous measurements (Del Rio et al. 2019) have confirmed the formation of cool summer microclimates through a combination of passive cooling elements (i.e., evaporative cooling louver, vegetation, and sunscreen) in semi-outdoor building spaces in Japan. Computational fluid dynamics (CFD) simulation is useful to understand the contribution of each element to semi-outdoor and indoor microclimates with natural ventilation, and to determine their effective combination. To date, there have not been sufficient studies on the modeling and validation for the CFD simulation of microclimates by such elements. This study demonstrates the modeling method using literature-based values and field measurements. It also demonstrates model validity by comparing the obtained results with field measurements. The results show that CFD simulation with detailed modeling of these elements can replicate vertical temperature distributions at four different positions across the semi-outdoor space and indoor space. The maximum difference in air temperature between the measurements and simulation results was 0.7–1 °C. The sensitivities of each passive cooling element on the microclimates formed in both spaces were confirmed. The watered louver condition and shorter louver–window distance were most effective in cooling both spaces. These results indicate that the modeling method could be effectively applied to assess cool microclimates and formulate a passive cooling design.

scholarly journals Assessment of Natural Ventilation System for a Typical Residential House in Poland

2016 ◽  
Vol 22 (3) ◽  
pp. 25-44 ◽  
Author(s):  
Romana Antczak-Jarząbska ◽  
Marek Krzaczek
Keyword(s):  
Natural Ventilation ◽  
Flow Direction ◽  
Air Flow ◽  
Ventilation System ◽  
Winter Season ◽  
Residential Building ◽  
Field Measurements ◽  
Significant Deterioration ◽  
Climate Conditions ◽  
Ventilation Performance

Abstract The paper presents the research results of field measurements campaign of natural ventilation performance and effectiveness in a residential building. The building is located in the microclimate whose parameters differ significantly in relation to a representative weather station. The measurement system recorded climate parameters and the physical variables characterizing the air flow in the rooms within 14 days of the winter season. The measurement results showed that in spite of proper design and construction of the ventilation system, unfavorable microclimatic conditions that differed from the predicted ones caused significant reduction in the efficiency of the ventilation system. Also, during some time periods, external climate conditions caused an opposite air flow direction in the vent inlets and outlets, leading to a significant deterioration of air quality and thermal comfort measured by CO2 concentration and PMV index in a residential area.

Thermocouple Psychrometer for Field Measurements

1951 ◽  
Vol 32 (6) ◽  
pp. 217-220 ◽  
Author(s):  
F. R. Bellaire ◽  
L. J. Anderson
Keyword(s):  
Air Temperature ◽  
Natural Ventilation ◽  
Field Measurements ◽  
Remote Locations ◽  
Thermocouple Psychrometer ◽  
Temperature And Humidity ◽  
Temperature Errors

A new thermocouple psychrometer, designed to indicate true air temperature and humidity in remote locations, is described. In order to minimize maintenance, it utilizes natural ventilation, but provides adequate shielding of sensing elements against radiation. Wet and dry bulb temperature errors of less than + 0.1C° are obtained in winds above 1 mph.

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