Field experimental study on the cooling effect of mine cooling system acquiring cold source from return air

With the increase of mining depth, more and deeper coal mines are limited by heat disaster. The cooling energy in deep mine cooling system comes from mine water inrush or ground cooling tower, but we cannot adopt the two methods because mine water inrush in many old coal mines in China is limited. What is more, the cooling pipelines cannot be put in narrow pit-shaft. To settle the problem above, according to the characteristics of Zhangxiaolou Coal Mine, this paper adopts the deep mine return air as the cooling energy for deep mine cooling system. In addition, we carried out cite test to extract cold energy from return air. Through monitoring the water quantity, water temperature of cooling system and air temperature, we got the thermodynamic equilibrium parameters during the cooling energy acquisition analysis and the effect of cooling system that the temperature and humidity on working face are respectively reduced to 8-12 ℃ and 8-15% through cooling. This research offers experimental reference for deep mine cooling which lacks cooling energy.

ANALYSIS OF THE COLD AIR EFFECT ON AN EXTREME PRECIPITATION EVENT TRIGGERED BY AN INVERTED TROUGH OF TYPHOON HAIKUI(1211)

Based on intensive automatic weather station data, satellite cloud imagery, NCEP reanalyzed data, and the simulation results from mesoscale numerical models, this study analyzes the characteristics and formation mechanisms of the mesoscale convection system(MCS) during the extreme precipitation event that was triggered by a weakened low-pressure inverted trough of Typhoon Haikui on August 10/2012. The results of this study show that cold air at the rear of a northeastern cold vortex creates thermodynamic conditions favorable to the development of extreme precipitation. The main body of the cold air is northward located so that the cold air invades only the middle layer of the periphery of the inverted trough. Thus, the cold air minimally affects the lower layer, which results in a vertically distributed structure of the temperature advection that augments the formation and development of convective instability stratification. In the middle troposphere, the cold air encounters the convergent, ascending, warm moist air from the low-pressure inverted trough, leading to frontogenesis. The frontogenesis enhances wind convergence which, in turn, further enhances the frontogenesis, and the positive feedback between these two forces augments the development of meso- and small-scale convection systems in the rainstorm region and its vicinity, which strengthens the upward transportation of water vapor from low layers and thickening of water vapor convergence and results in local heavy rains.

Some Characteristics of the Surface Boundary Layer of a Strong Cold Air Process over Southern China

In southern China, cold air is a common weather process during the winter season; it can cause strong wind, sharp temperature decreases, and even the snow or freezing rain events. However, the features of the atmospheric boundary layer during cold air passage are not clearly understood due to the lack of comprehensive observation data, especially regarding turbulence. In this study, four-layer gradient meteorological observation data and one-layer, 10-Hz ultrasonic anemometer-thermometer monitoring data from the northern side of Poyang Lake were employed to study the main features of the surface boundary layer during a strong cold-air passage over southern China. The results show that, with the passage of a cold air front, the wind speed exhibits low-frequency variations and that the wind systematically descends. During the strong wind period, the wind speed increases with height in the surface layer. Regular gust packets are superimposed on the basic strong wind flow. Before the passage of cold air, the wind gusts exhibit a coherent structure. The wind and turbulent momentum fluxes are small, although the gusty wind momentum flux is slightly larger than the turbulent momentum flux. However, during the invasion of cold air, both the gusty wind and turbulent momentum fluxes increase rapidly with wind speed, and the turbulent momentum flux is larger than the gusty wind momentum flux during the strong wind period. After the cold air invasion, this structure almost disappears.

THE ROLE OF COLD AIR AND CHARACTERISTICS OF WATER VAPOR IN BOTH TCS NANMADOL (0428) AND IRMA (7427) MAKING LANDFALL ON CHINA IN WINTERTIME

The NCEP/NCAR reanalysis data are used to investigate the role of cold air and moisture characteristics during the evolution of two cases of tropical cyclones (Nanmadol and Irma) which made landfall on China in wintertime. The results are shown as follows. (1) The East Asia trough steered the cold air into the tropical ocean in early winter. The tropical cyclones moved in opposite directions with a high moving out to sea and the enhancement of the pressure gradient at the periphery played a role in maintaining and strengthening the intensity of the storms. The intrusion of weak cold air into the low levels of the tropical cyclones strengthened them by improving the cyclonic disturbance when they were still over the warm sea surface. When the cold air was strong enough and intruded into the eyes, the warm cores were damaged and stuffed before dissipation. (2) The tropical cyclones were formed in a convergence zone of moisture flux and their development could enhance the disturbance of water vapor convergence, thus strengthening the moisture convergence zone. However, when they were outside the moisture zone, the storms could not gain sufficient water vapor and became weak. There were no belts of strong moisture transportation during the wintertime tropical cyclone processes.

A Study on a Snowband Associated with a Coastal Front and Cold-Air Damming Event of 3-4 February 1998 along the Eastern Coast of the Korean Peninsula

A 24-h simulation with the Advanced Regional Prediction System （ARPS） nonhydrostatic model is performed for the heavy snowfall event of 3-4 February 1998 along the eastern coast of Korean Peninsula; the results are used to understand the snowfall process, including why the precipitation maxima formed along the Yeongdong coastal region rather than over the mountain slope and ridge top during. The numerical simulation with a 4-kin horizontal grid spacing and 43 levels reproduces very well the narrow snowband located off the eastern Korean coast, away from, instead of over, the Yeongdong coastal mountain range. The general evolution of the snowband agrees quite well with radar observations, while the water-equivalent precipitation amount agrees reasonably well with radar precipitation estimate. The simulation results clearly show that the snow band developed due to the lifting by a coastal front that developed because of the damming of cold air against the eastern slope of the coastal mountain range. The damming was enhanced by the advection of cold air by a tow-level mountain-parallel jet from the north, formed due to geostrophic adjustment as the on-shore upslope air was decelerated by the mountain blocking. As the onshore flow weakened later due to synoptic-scale flow pattern change, the cold front propagated off shore and the precipitation dissipated.

A novel approach to regulate cell membrane permeability for ATP and NADH formation in Saccharomyces cerevisiae induced by air cold plasma

Air cold plasma has been used as a novel method for enhancing microbial fermentation. The aim of this work was to explore the effect of plasma on membrane permeability and the formation of ATP and NADH in Saccharomyces cerevisiae, so as to provide valuable information for largescale application of plasma in the fermentation industry. Suspensions of S. cerevisiae cells were exposed to air cold plasma for 0, 1, 2, 3, 4 and 5 min, and then subjected to various analyses prior to fermentation （Oh） and at the 9 and 21 h stages of fermentation. Compared with nonexposed cells, cells exposed to plasma for 1 min exhibited a marked increase in cytoplasmic free Ca2＋ concentration as a result of the significant increase in membrane potential prior to fermentation. At the same time, the ATP level in the cell suspension decreased by about 40%, resulting in a reduction of about 60% in NADH prior to culturing. However, the levels of ATP and NADH in the culture at the 9 and 21 h fermentation stages were different from the level at 0 h. Taken together, the results indicated that exposure of S. cerevisiae to air cold plasma could increase its cytoplasmic free Ca2＋ concentration by improving the cell membrane potential, consequently leading to changes in ATP and NADH levels.

Hemostasis Efficacy and Mechanism of Cold Atmospheric Air Plasma

The capacity of a cold atmospheric-pressure air plasma (CAAP) device for advanced first aid is presented. Using swine as an animal model, two trials: 1) a large, curved cut in hindquarters area and 2) amputation of a front leg, were performed. Cold atmospheric-pressure air plasma effluent, which carries reactive oxygen species (ROS) atomic oxygen (OI), is applied for wound treatments. Swift hemostasis of the wounds by the CAAP treatment was demonstrated. The pressure applied by a finger on the cut arteries in trial 1 and the tourniquet applied in trial 2 could be removed immediately after the treatment and there was no re-bleed in both cases. CAAP hemostasis mechanism was explored via in-vitro tests. The tests on sodium citrate mixed blood-droplet samples show that 1) the heat delivered by the CAAP has no impact on the observed clot formation, 2) plasma effluent activates platelets to promote coagulation state and cascade, and 3) the degree of clotting increases with the total amount of applied OI by means of the CAAP effluent. It took only 16 s of the CAAP treatment to reach full clotting, which was considerably shortened from the natural clotting time of about 25 minutes. The tests on smeared blood samples show that the reduction of the platelet count and the increase of RBC count are proportional to the amount of applied OI. A plausible CAAP hemostasis mechanism is concluded from the in vitro test results and the animal model trials.

DOPPLER RADAR ECHO CHARACTERISTICS FOR COLD AIR INTRUDING INTO TYPHOON CHANCHU

With Doppler radar data from Shantou and Xiamen and the National Centers for Environmental Prediction and the National Center for Atmospheric Research （NCEP/NCAR） reanalysis data, the characteristics of a short-term heavy rainstorm on 17 May 2006 caused by Typhoon Chanchu are studied. Doppler radar data indicates that during the period from 1800 to 1900 May 17, the azimuthal phases of the positive and negative radial wind maximums are asymmetric around the core radius of the typhoon, i.e., the radial wind on the left side of the track is anomalously larger than that on the right side. Studies show that this is induced by the intrusion of cold air （northeasterly wind）, which is primarily located at the mid-lower layers, lower than 4 kin; this is due to the intruding cold air that forces the atmosphere to uplift, enhancing the release of instability energy, which triggers the heavy precipitation. During the late stage of the cold air activity, the typhoon is rapidly weakened. Consistent with the radar-observed intrusion of cold air, the NCEP/NCAR reanalysis of wind data also shows that there are obvious large scalar wind values at the mid-lower layers （approximately 1-3 km） to the left of the typhoon center （1800 May 17）, and in all regions--except those affected by the intruding cold air--the wind speeds on the right side of the track remain larger than those on the left side. Furthermore, the Rankine model results confirm that northeasterly cold air is introduced to the typhoon at the mid-lower layers to the left of the track. Calculations also point out that there exists a frontal zone with high θse that tilts from southeast to northwest with height and the super heavy rainstorm occurring in the south of Fujian province lies just near the fxontal zone.

Air-sea fluxes of heat and momentum over the Yellow Sea during cold air outbreaks

The impact of sea surface waves on air-sea fluxes of heat and momentum over the Yellow Sea caused by cold fronts during cold air outbreak(CAO)events is investigated through numerical experiments with a FVCOM-SWAVE(Finite-Volume Coastal Ocean Model-Surface WAVE)wave-current coupled model.Two typical types of cold fronts,i.e.,those respectively from the north and from the west,are simulated and compared to each other and with monthly mean.During cold seasons,currents in the Yellow Sea are weaker than that during warm seasons.As a result,waves show a more prominent impact.The numerical simulations suggested that both the heat and momentum fluxes are significantly enhanced during CAO events;and they could be a few times larger than the monthly average of a five-year mean.The enhancement is highly sensitive to the features of CAOs.Specifically,it depends on the cold front orientation,intensity and evolution.One mechanism that strengthens the two fluxes is via sea waves.For the CAOs that are studied,an increase in sea wave height by 50%can double the maximal momentum flux,and cause an increase in heat flux by 10-160 W/m^2.

Effects of cryogenic cold air jet cutting on chip break in metal machining

The half-dry cutting employs cryogenic compressed air cooled down to (10 to 40) and a micro-dosage of lubricating oil, called cryogenic cold air jet cutting was studied. On the basis of a comparative experiment on dry and cryogenic cold air jet cuttings carried out for grade 45 steel, the effects of cryogenic cold air jet on the breaking of chips were discussed. The experimental results reveal that in the valid ranges of pressure and temperature, the cryogenic cold air jet widens the chip breaking areas effectively. When the cutting depth is not greater than 1 mm, the influence of chip breaking is much more significant. But different injecting angle of cold air has different influence on the chip-break. From the experiment, the optimized jet injecting angle, temperature effecting range and pressure working range of cold air are obtained. These results can offer a foundation for industrial manufacturing.

Analysis and Discussion of a Strong Cold Air Process in Spring

Based on NCEP 1°×1°daily reanalysis data and conventional surface observation data,the potential vortex theory was used to analyze a strong cold air activity process of Karamay during May 15-16,2019.The results showed that the weather had obviously baroclinic characteristic.A strong cold tongue extended straight to Central Asia from the high latitude area,and the cold air was strong and deep.The driving effect of cold trough could accelerate it to move southward.The Aral Sea low vortex obstructed the warm air in the north in high latitude area,and the southwest air flow in the front of the vortex conducted to the transportation of water vapor to Central Asia.Compared with the climate average field of 1981-2010,the northwest flow at 500 hPa in May of 2019 was aggressive,which had frequently influenced Xinjiang by cold air from the north high latitude regions.The east flow of the bottom layer not only input cold air to Karamay,but also formed the windward slope effect with the terrain.Moreover,it increased the vertical wind shear and induced the upward movement.The center of high potential vorticity with high latitude fell southward,and the center of low potential vorticity in Central Asia moved eastward rapidly.They combined and then moved toward Xinjiang,which made the strong cold air erupt rapidly.When the right side of the moved axis of the high potential vorticity center and the strong west flow superposed over the Karamay area,the center of the strong rainfall area appeared 6 h later.

Analysis of a Large Scale Cold Air Weather Process in China during January 2021

This study uses data provided by the National Meteorological Information Center of China, Japan Meteorological Agency (JMA) and National Oceanic Atmospheric Administration (NOAA) Physical Sciences Laboratory of the USA to analyze a cold air weather process at the beginning of January 2021. Synoptic analysis is mainly used to summarize synoptic laws or patterns based on observational data, and describe and infer weather processes. The main conclusions are as follows: The cold air travels south along the northwest path, affecting most of China. During the cold wave process, the first cold air is weak, which has a certain cooling effect on northern China. The second cold air was guided by the low vortex, the accumulation in the transverse groove of Mongolia was strengthened, and the cooling effect was significant. The southwest jet showed an increasing trend, and the water vapor transport conditions were good. However, due to the relatively gentle southern branch system, the warm and humid air flow was weak and the precipitation level was small. The purpose of this study is to better understand a large-scale cold air weather process in January 2021 in China.

Analysis of Cold Air and Precipitation in Central and Eastern China, 2-5 October, 2022

This paper used potential height field data published by the China National Climate Center and the US NCEP reanalysis data. A study was conducted on a strong cold wave weather process in central and eastern China from October 2 to 5, 2022. The results show that this weather process is a cold air weather process of “horizontal trough to vertical” type from the east of Novaya Zemlya Island. Cold air passes through Russia and Mongolia south, controlling northern China. The precipitation process is caused by the combination of high-altitude trough, ground front, warm and humid air flow, and precipitation weather formed by the influence of warm and humid air due to the 700 hPa shear line. The northern Sichuan Basin and the middle and lower reaches of the Yellow River in China can precipitate almost 50 mm. Water vapor is transported from the South China Sea to central and eastern China by the southwest warm and humid air flow along the west side of the West Pacific Subtropical High. Water vapor is concentrated over the precipitation area through horizontal convergence and is the most important source of water vapor causing precipitation.

Optimization of Selecting Air Conditioning Cold/Heat Sources with Grey Relation Analysis

Selection of air conditioning（AC） cold/heat sources generally concerns about certain aspects and cannot reveal the whole profile of the problems. Grey relation analysis （GRA） is a data processing method to categorize the correlation extent of compared sequences and a certain reference sequence in a system with uncertain information. It is applied to evaluating and selecting AC cold/heat sources from four main aspects, which are technology, economy, reliability, and operation and management. Case study shows that the result for selecting AC cold/heat sources with the GRA method can be more reasonable and convincible. Thus it offers a new approach for designers in heating, ventilating and air conditioning field to compare and evaluate different AC cold/heat sou rces.

A Cold Model Aerodynamical Test of Air-Staged Combustion in a Tangential Firing Utility Boiler

The purpose of this paper is to present the flow field in the 300MW tangential firing utility boiler that used the Low NOx Concentric Firing System （LNCFS）. Using the method of cold isothermal simulation ensures the geometric and boundary condition similarity. At the same time the condition of self-modeling is met. The experimental results show that the mixture of primary air and secondary air becomes slower, the average turbulence magnitude the relative diameter of the tangential firing enlarges of the main combustion zone becomes less and when the secondary air deflection angle increases When the velocity pressure ratio of the secondary air to the primary air （p2/p1） enlarges, the mixture of the secondary air and the primary air becomes stronger, the average turbulence magnitude of the main combustion zone increases, and the relative diameter of the tangential firing becomes larger. Because the over fire air （OFA） laid out near the wall has a powerful penetration, the relative diameter of the tangential firing on the section of the OFA is very little, but the average turbulence magnitude is great. When the velocity pressure ratio of the OFA to the primary air POFA/p1 increases, the relative diameter of the tangential firing on the section of the OFA grows little, the average turbulence magnitude becomes larger and the penetration of the OFA becomes more powerful.

夏热冬冷地区某三甲医院空调制冷机房运行性能实测研究

医院建筑夏季供冷需求高,实现制冷机房高效运行具有显著的节能减排效益。以夏热冬冷地区某三甲医院为研究对象,通过对其空调制冷机房在夏季的运行性能进行实测研究,总结出冷水机组运行负荷率偏低,蒸发器与冷凝器换热性能不佳,冷水、冷却水系统缺乏合理调控导致的大流量小温差等问题,并提出了优化措施。研究结果旨在为同类建筑制冷机房节能运维提供建议。

谷电相变蓄冷空调系统在某大型商业超市应用的性能分析及经济性评价

以深圳某商业超市空调制冷工程为例,结合峰谷电价差,针对水合盐相变蓄冷技术在大规模舒适性商业领域的应用进行了性能分析及经济性评价。该项目采用原制冷机房中备用制冷机组作为冷源,相变蓄冷机组夜间利用谷电蓄冷,白天将冷量供给商业超市空调制冷系统,满足用户用冷需求。本文系统测试并分析了谷电相变蓄冷系统连续运行14天的蓄、放冷温度,蓄冷量,耗电量等实验数据。结果表明:相比原有制冷系统,采用谷电相变蓄冷系统作为冷源时,夜间制冷机组的性能系数(COP)和系统能效比(EER)大幅提高;该项目的投资回收期为5.35 a,随着峰谷电价差逐步拉大,当峰谷电价差≥1.06元/(kW·h)时,系统的投资回收期≤4 a;水合盐相变蓄冷技术结合谷电/弃电等在大规模舒适性商用空调领域应用具有可行性。

Detection of the synoptic southeastward-extending Siberian cold high during 1978-2017

To better understand the relationship between anticyclones in Siberia and cold-air activities and temperature changes in East Asia,this study proposes a 2D anticyclone identification method based on a deep-learning model,Mask R-CNN,which can reliably detect the changes in the morphological characteristics of anticyclones.Using the new method,the authors identified the southeastward-extending Siberian cold high(SEESCH),which greatly affects wintertime temperatures in China.This type of cold high is one of the main synoptic systems(45.7%)emerging from Siberia in winter.Cold air carried by SEESCH has a significant negative correlation with the temperature changes in the downstream area,and 52% of SEESCHs are accompanied by cold-air accumulation in North and East China,which has a significant impact on regional cooling.These results provide clues for studying the interconnection between SEESCHs and extreme cold events.

Analysis of Cold Weather Process in the North China during October 20 to 23, 2020

To help the forecast of cold weather activity, the cold weather process in the North China from October 20 to 23, 2020 was analyzed by the methods of utilizing statistical analysis, such as composite, differential analysis and correlation analysis, and by using the data from the National Meteorological Information Center of China, the National Climate Center of China and the NECP data from NOAA Physical Sciences Laboratory. The results show that: 1) the cold air started from Siberia, took the east path to move southward, and finally affected most part of North China. 2) Almost no obvious weather occurred during the process. 3) The cold air mainly moved along with the form and development of the trough and ended when the trough got weaken.

Mesoscale Impacts on Cold Season PM_(2.5) in the Yukon Flats

Near-surface PM2.5 and meteorological observations were performed in three rural communities in the high latitude Yukon Flats valley at various times during the cold season (October to April). These data were synthesized with data from other meteorological sites, NCEP reanalysis and MAIAC retrieved aerosol optical depths data to analyze the role of mesoscale processes and radiation on air quality. Under weak large-scale forcing mountain-valley circulations develop that are driven by the differences in insolation. During the long dark nights, radiative cooling occurs in the near-surface layer of the mountain slopes of the Brooks, Ogilvie and White Mountains Ranges and at the bottom of the valley. Here surface-based inversions (SBI)—known as roof-top inversions—forms, while the cold air drains from the slopes. A frontal wedge forms when the cold air slides over the relatively colder air in the valley. Drainage of cold air from the Brooks Range governed the circulation and cold air pooling in the valley. Concentrations during times with and without SBI differed significantly (at 95% confidence) at two sites indicating that local emissions were the major contributor. At the site, which is closest to the mountains, concentrations marginally changed in the presence of inversions. At all sites, 24-h mean PM2.5 remained below the National Ambient Air Quality Standard.