Research on Cooling Effect on Heading Face of Spray by CFD in Metal Mines

Mesin pengkondisian udara umumnya digunakan untuk memberikan efek pendinginan (cooling effect). Efek pendinginan dimaksudkan untuk memberikan kenyamanan di ruang yang didinginkan, sehingga rasa nyaman membuat orang betah didalamnya. Mesin pengkondisian udara secara termodinamika kebanyakan beroperasi menggunakan siklus kompresi uap, dimana panas diserapkan disisi evaporator di dalam ruangan, kemudian panas tersebut dibuang di kondensor di luar ruangan. Proses tersebut dapat berlangsung karena kerja kompresor dan penurunan tekanan yang terjadi pada katup ekpansi atau pipa kapiler, sehingga siklus kompresi uap bekerja sempurna. Pada sistem pengkondisian udara biasanya panas terbuang kelingkungan begitu saja, panas tersebut dapat dimanfaatkan untuk memanaskan air dengan penambahan kondensor dummy. Penambahan kondensor dummy pada penelitian ini dilakukan untuk melihat pengaruh penambahan kondensor dummy terhadap beban pendingin, daya kompresi, temperatur, dan Coefficient of Performance (COP). Metode yang digunakan pada penelitian ini ialah metode rancang bangun dan eksperimental. Berdasarkan hasil pengujian, selama pengoperasian 120 menit diperoleh temperatur air panas pada kondisi tanpa beban (0W), beban 1000W, 2000W dan 3000W berturut-turut adalah 52,83oC, 56,58oC, 57,93oC dan 64,73oC.

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The Combination of Building Greenery and Photovoltaic Energy Production—A Discussion of Challenges and Opportunities in Design

Sustainability ◽

10.3390/su13031537 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1537

Author(s):

Irene Zluwa ◽

Ulrike Pitha

Keyword(s):

Energy Production ◽

Substrate Surface ◽

Relevant Literature ◽

Green Roofs ◽

Cooling Effect ◽

Photovoltaic Energy ◽

Pv Systems ◽

System A ◽

Challenges And Opportunities ◽

Building Surfaces

In the case of building surfaces, the installation of green roofs or green facades can be used to reduce the temperature of the environment and the building. In addition, introducing photovoltaic energy production will help to reduce CO2 emissions. Both approaches (building greenery and photovoltaic energy production) compete, as both of them are located on the exterior of buildings. This paper aims to give an overview of solutions for the combination of building greenery (BG) systems and photovoltaic (PV) panels. Planning principles for different applications are outlined in a guideline for planning a sustainable surface on contemporary buildings. A comprehensive literature review was done. Identified solutions of combinations were systematically analysed and discussed in comparison with additional relevant literature. The main findings of this paper were: (A) BG and PV systems with low sub-construction heights require shallow substrates/low growing plants, whereas in the case of the combination of (a semi)-intensive GR system, a distance of a minimum 60 cm between the substrate surface and lower panel edge is recommended; (B) The cooling effect of the greenery depends on the distance between the PV and the air velocity; (C) if the substrate is dry, there is no evapotranspiration and therefore no cooling effect; (D) A spectrum of different PV systems, sub-constructions, and plants for the combination of BG and PV is necessary and suitable for different applications shown within the publication.

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Cooling effect of fungal stromata in the Dactylis-Epichloë-Botanophila symbiosis

Communicative & Integrative Biology ◽

10.1080/19420889.2021.1938824 ◽

2021 ◽

Vol 14 (1) ◽

pp. 151-157

Author(s):

Marlena Lembicz ◽

Zbigniew Miszalski ◽

Andrzej Kornaś ◽

Katarzyna Turnau

Keyword(s):

Cooling Effect

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Investigations on the effect of different influencing factors on film cooling effectiveness under the injection of synthetic coolant

Scientific Reports ◽

10.1038/s41598-021-83080-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jianlong Chang ◽

Xinlei Duan ◽

Yang Du ◽

Baoquan Guo ◽

Yutian Pan

Keyword(s):

Film Cooling ◽

Elliptical Hole ◽

Synthetic Jet ◽

Cooling Effect ◽

Flow Structures ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

Cooling Flow ◽

Cooling Method ◽

Strong Controllability

AbstractBy combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. Numerical simulations of the synthetic coolant ejected are carried out for analyzing the cooling performance in detail, under different blowing ratios, hole patterns, Strouhal numbers, and various orders of incidence for the two rows of holes. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. Due to the strong controllability of the synthetic coolant, the synthetic coolant can be controlled through adjusting the frequency of blowing and suction, so as to change the interaction between vortex structures for improving film cooling effect in turn. As a result, the synthetic coolant ejection is more advisable in certain conditions to achieve better outcomes.

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Quantitative Risk Assessment for Deep Tunnel Failure Based on Normal Cloud Model: A Case Study at the ASHELE Copper Mine, China

Applied Sciences ◽

10.3390/app11115208 ◽

2021 ◽

Vol 11 (11) ◽

pp. 5208

Author(s):

Jianpo Liu ◽

Hongxu Shi ◽

Ren Wang ◽

Yingtao Si ◽

Dengcheng Wei ◽

...

Keyword(s):

Risk Assessment ◽

Large Scale ◽

Cloud Model ◽

Quantitative Risk Assessment ◽

Geological Condition ◽

Deep Tunnel ◽

Entropy Weight ◽

Copper Mine ◽

Evaluation Indexes ◽

Metal Mines

The spatial and temporal distribution of tunnel failure is very complex due to geologic heterogeneity and variability in both mining processes and tunnel arrangement in deep metal mines. In this paper, the quantitative risk assessment for deep tunnel failure was performed using a normal cloud model at the Ashele copper mine, China. This was completed by considering the evaluation indexes of geological condition, mining process, and microseismic data. A weighted distribution of evaluation indexes was determined by implementation of an entropy weight method to reveal the primary parameters controlling tunnel failure. Additionally, the damage levels of the tunnel were quantitatively assigned by computing the degree of membership that different damage levels had, based on the expectation normalization method. The methods of maximum membership principle, comprehensive evaluation value, and fuzzy entropy were considered to determine the tunnel damage levels and risk of occurrence. The application of this method at the Ashele copper mine demonstrates that it meets the requirement of risk assessment for deep tunnel failure and can provide a basis for large-scale regional tunnel failure control in deep metal mines.

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Comparative analysis of shade and underlying surfaces on cooling effect

Urban Forestry & Urban Greening ◽

10.1016/j.ufug.2021.127223 ◽

2021 ◽

pp. 127223

Author(s):

Mohammad A. Rahman ◽

Vjosa Dervishi ◽

Astrid Moser-Reischl ◽

Ferdinand Ludwig ◽

Hans Pretzsch ◽

...

Keyword(s):

Comparative Analysis ◽

Cooling Effect

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Cooling Effect of Different Land Cover Types: A Case Study in Xi’an and Xianyang, China

Sustainability ◽

10.3390/su13031099 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1099

Author(s):

Yuhe Ma ◽

Mudan Zhao ◽

Jianbo Li ◽

Jian Wang ◽

Lifa Hu

Keyword(s):

Land Cover ◽

Surface Temperature ◽

Urban Heat Island ◽

Land Surface Temperature ◽

Land Surface ◽

Cooling Effect ◽

Heat Island ◽

Land Cover Types ◽

Island Effect ◽

Urban Heat

One of the climate problems caused by rapid urbanization is the urban heat island effect, which directly threatens the human survival environment. In general, some land cover types, such as vegetation and water, are generally considered to alleviate the urban heat island effect, because these landscapes can significantly reduce the temperature of the surrounding environment, known as the cold island effect. However, this phenomenon varies over different geographical locations, climates, and other environmental factors. Therefore, how to reasonably configure these land cover types with the cooling effect from the perspective of urban planning is a great challenge, and it is necessary to find the regularity of this effect by designing experiments in more cities. In this study, land cover (LC) classification and land surface temperature (LST) of Xi’an, Xianyang and its surrounding areas were obtained by Landsat-8 images. The land types with cooling effect were identified and their ideal configuration was discussed through grid analysis, distance analysis, landscape index analysis and correlation analysis. The results showed that an obvious cooling effect occurred in both woodland and water at different spatial scales. The cooling distance of woodland is 330 m, much more than that of water (180 m), but the land surface temperature around water decreased more than that around the woodland within the cooling distance. In the specific urban planning cases, woodland can be designed with a complex shape, high tree planting density and large planting areas while water bodies with large patch areas to cool the densely built-up areas. The results of this study have utility for researchers, urban planners and urban designers seeking how to efficiently and reasonably rearrange landscapes with cooling effect and in urban land design, which is of great significance to improve urban heat island problem.

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High-Resolution Modelling of Thermal Exposure during a Hot Spell: A Case Study Using PALM-4U in Prague, Czech Republic

Atmosphere ◽

10.3390/atmos12020175 ◽

2021 ◽

Vol 12 (2) ◽

pp. 175

Author(s):

Jan Geletič ◽

Michal Lehnert ◽

Pavel Krč ◽

Jaroslav Resler ◽

Eric Scott Krayenhoff

Keyword(s):

Czech Republic ◽

Urban Areas ◽

Heat Exposure ◽

Thermal Exposure ◽

Urban Environments ◽

Cooling Effect ◽

Spatiotemporal Variability ◽

Climate Index ◽

Street Canyons ◽

General Terms

The modelling of thermal exposure in outdoor urban environments is a highly topical challenge in modern climate research. This paper presents the results derived from a new micrometeorological model that employs an integrated biometeorology module to model Universal Thermal Climate Index (UTCI). This is PALM-4U, which includes an integrated human body-shape parameterization, deployed herein for a pilot domain in Prague, Czech Republic. The results highlight the key role of radiation in the spatiotemporal variability of thermal exposure in moderate-climate urban areas during summer days in terms of the way in which this directly affects thermal comfort through radiant temperature and indirectly through the complexity of turbulence in street canyons. The model simulations suggest that the highest thermal exposure may be expected within street canyons near the irradiated north sides of east–west streets and near streets oriented north–south. Heat exposure in streets increases in proximity to buildings with reflective paints. The lowest heat exposure during the day may be anticipated in tree-shaded courtyards. The cooling effect of trees may range from 4 °C to 9 °C in UTCI, and the cooling effect of grass in comparison with artificial paved surfaces in open public places may be from 2 °C to 5 °C UTCI. In general terms, this study illustrates that the PALM modelling system provides a new perspective on the spatiotemporal differentiation of thermal exposure at the pedestrian level; it may therefore contribute to more climate-sensitive urban planning.

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