Distribution Of Thermal Environment Research Articles

Analysis of spatial–temporal evolution trends and influential factors of desert-oasis thermal environment in typical arid zone: The case of Turpan–Hami region

As a typical geographic landscape unit in the arid zone of northwest China, the distribution of the thermal environment in the substratum of the desert-oasis is of great significance to the monitoring of the ecological environment and the quality of human habitat in the region. The purpose of this research is to reveal the spatial–temporal evolution pattern of the thermal environment of the desert–oasis in the Turpan–Hami region from 2005 to 2020 and its trend changes, and to investigate the relationship between natural and human factors and the thermal environment and to conduct a long time series analysis. Firstly, the accuracy of MODIS land surface temperature (LST) data combined with site data was verified. Secondly, the mean-standard deviation method is used to identify desert heat island and oasis cold island zones. Again, the spatial–temporal distribution and change trends of thermal environment are explored by using standard deviation ellipse and spatial autocorrelation combined with land use/land cover (LULC) types. Finally, based on the multi-source remote sensing data, the natural factors and human factors are selected to explore their correlation with the thermal environment using Pearson correlation analysis. The results show that (1) the desert heat island zones are distributed in the desert areas on the periphery of urban built-up areas in Gaochang District, Shanshan County and Yizhou District of Hami Region. The oasis cold island zones are concentrated in the urban built-up areas of Gaochang District and Yizhou District, mainly because the vegetation coverage of urban built-up areas is higher than that of the peripheral desert areas. (2) The spatial development characteristics of the extremely high temperature (EHT) zone and the high temperature (HT)zone from 2005 to 2020 are “southeast-northeast-northwest” and “southeast-northwest” respectively, and the area of construction land 16a increased by 0.31%. This indicates that the spatial evolution of the thermal environment is closely related to the LULC and the degree of urbanization development. (3) From a four–period image with P < 0.001 and Z > 2.58, the thermal environment displays a high positive spatial correlation with Moran's I values of 0.45, 0.54, 0.47, and 0.45. (4) Temperature (Tem), downward longwave radiation (LWdown), and nighttime light intensity (NPP) all exhibited positive correlations with the LST and are significant in the desert region (p < 0.05); The albedo exhibited negative correlations with the LST and is significant in the grassland and woodland regions (p < 0.05).

室内温熱環境分布に基づく座席移動が在室者全体の熱的満足度に及ぼす影響

This study examines the effect on the overall occupant thermal satisfaction when information is provided on seating movement in an appropriate combination of indoor thermal environment distribution and individual thermal preferences, using an individual thermal preference survey through a subject experiment, CFD analysis, and multi-agent simulation. The modeling of occupant's seat shifting behavior using the allowable PMV band as a new index shows that free addressing and providing information during seat shifting improves the overall occupant's thermal satisfaction. In addition to the recommendation of the destination of the information, the seat exchange recommendation further improves the satisfaction level.

Numerical investigation on air distribution characteristics and effect of the outlet opening mode on cross-shaped column attachment ventilation

The conventional (square and circular) column attachment ventilation theory has been developed for many years. However, it is still unclear whether the cross-shaped column can be effectively applied to column attachment ventilation. This paper compared three column attachment ventilation models (i.e., circular, square and cross-shaped) by numerical simulation and experimental methods, the latter of which were mainly employed to verify and optimize the CFD model. The air distribution of these three ventilation models was studied in isothermal mode. Five cross-shaped column air supply outlet opening modes under cooling conditions were proposed, and their effects on the thermal environment distribution in the occupied zone were investigated. The intersection of the two attached airflows in the inner concave surface of the cross-shaped column changed the trends of the axial velocity variation. The attached airflow created a larger impinging zone near the internal corner of the cross-shaped column compared with the other surfaces. With the fixed air supply parameters, the kinetic energy loss at the column bottom under cross-shaped column attachment ventilation (CS-CAV) increased by approximately 60 % compared with that under square column attachment ventilation (S-CAV). CS-CAV is not only an effective ventilation method but can also meet the comfort needs of different occupied zones, providing a design basis for CS-CAV in buildings.

Influence of different building transparent envelopes on energy consumption and thermal environment of radiant ceiling heating and cooling systems

In this study, the energy consumption and indoor thermal environment of a radiant ceiling heating and cooling system with three types of transparent building envelopes, namely, ordinary insulating glass (OIG), heat reflective insulating glass (HFIG) and triple silver low-e insulating glass (TSIG), were investigated and compared by experiment and simulation. The annual energy consumption and thermal environment distribution of the radiant ceiling system equipped with the three types of transparent envelope in five different climate zones were obtained. The results show that the energy saving rates of HFIG and TSIG windows are −9.78% to 48.00% and 8.82–63.65% in the five climate zones, compared to the OIG window. It is seen that the TSIG window has greater energy-saving potential in both heating dominant and cooling dominant climate zones. In addition, the annual average air temperature of the room with TSIG window is more stable, which means the thermal environment level is better. It is also found that the response of radiant ceiling system to solar heat gain is different in summer and winter. It has a good response to cooling, and it can timely take away the influence of solar heat gain through the radiation heat transfer. Therefore, the indoor thermal environment level of the rooms with different transparent envelopes has little difference during the cooling season. However, as the response of radiant ceiling systems to heating is poor, the indoor thermal environment is greatly affected by the outdoor parameters and varied with the transparent envelopes. Hence, adopting the transparent envelopes with high performance is preferred in the heating dominant zones.

Indoor thermal environmental evaluation of Chinese green building based on new index OTCP and subjective satisfaction

Abstract Due to energy crisis and phenomenon of global warming, green buildings have been undergoing vigorous development in China, and people are paying increasing attention to the actual operational effect of green buildings rather than the design. In this paper, 12 high-star green buildings (3 LEED Gold buildings, 1 operation Two-Star building, 1 operation Three-Star building, 1 design Two-Star building, and 6 design Three-Star buildings) in the cold region and hot summer and warm winter region (HSWW region) were taken as the research objects to evaluate their indoor thermal comfort. First, from December 2016 to March 2018, this paper conducted a continuous collection of indoor objective thermal environment data of green buildings to obtain the actual thermal environment distribution, and proposed new indexes to evaluate indoor thermal environment of green buildings, namely, OTCD (Over Thermal Comfort Distance) and OTCP (Over Thermal Comfort Percentage). It was found that indoor temperature and humidity of most buildings didn't reach the standard. The new evaluation indexes clearly showed the percentage of the indoor temperature and humidity of each green building away from the comfort zone under different standards in mathematical form, which is convenient for comparison. Second, a questionnaire survey on people's subjective satisfaction of indoor thermal comfort in green buildings was carried out at the same time, wherein 1400 valid questionnaires were recovered. Based on the different evaluation results of subjective and objective thermal comfort, the operative comfort temperature/humidity and thermal/humid comfort zone of different building climate zones were obtained by cluster and linear regression analysis. The results showed that there are differences between thermal/humid comfort zone of different building climate zones and it is helpful for the research on thermal comfort of green buildings in China and the development of relevant codes.

Analysis of remotely-sensed ecological indexes' influence on urban thermal environment dynamic using an integrated ecological index: a case study of Xi’an, China

ABSTRACTThe spatio-temporal pattern of surface ecological status affects urban thermal environment distribution significantly. Urban thermal pattern, however, is a complicated physical phenomenon involving a series of terrestrial environmental parameters. Thus, it is insufficient to employ only one ecological parameter for depicting the variation of land surface temperature (LST). This paper begins with the analysis of four ecological parameters' influence on LST using regression analysis, based on 24 Landsat images which cover Xi’an of China from 1992 to 2014. These four parameters include greenness degree (i.e. the soil adjusted vegetation index, SAVI), soil moisture degree (i.e. the normalized difference moisture index, NDMI), dryness degree (i.e. the normalized difference soil index, NDSI) and resident aggregation degree (i.e. the normalized difference build-up index, NDBI). Besides, contribution intensity index was introduced to investigate the contribution effect of four ecological parameters on LST, and a new ecological index, integrated ecological index (IEI), was founded using the principal component analysis technique to integratedly represent its spatial and mathematical correlations with LST. Results indicate that four ecological parameters all possessed pronounced performance in impacting LST pattern in all dates: SAVI and NDMI were found to be correlated negatively with LST, whereas NDBI and NDSI correlated positively with LST. Additionally, SAVI had a profound impact on LST distribution compared with the other three parameters, and there was the biggest heating contribution in the lowest SAVI category. Further finding suggests that IEI as a new ecological index can be used to integratedly estimate the spatio-temporal change of LST, manifesting a negative correlation with LST. Our study thinks that the comprehensive characterization of surface ecological status is conducive to benefit us to better understand the spatio-temporal mechanism of thermal environment and ecosystem and to help urban decision-makers to execute effective conservation policies for the ecosystem.

Evaluation metrics of thermal management in data centers based on exergy analysis

Cooling system has caused huge energy consumption in high-density data centers (DCs). Efficient thermal management makes a significant impact on energy saving of air conditioning system and safe operation of IT equipment. Air mixing in air flow space is an irreversible process leading to exergy loss from the view of Second-Law of Thermodynamics. In this paper, new exergetic evaluation metrics are proposed at room level and rack level respectively to reflect the causes and locations of inefficiency of cooling system in DCs. The effectiveness of new metrics is identified in a typical DC. Towards this, experimental measurement and numerical simulation are carried out to obtain the air distribution of thermal environment in a practical DC. Subsequently, the comparison with existing metrics demonstrates the applicability and advantage of new exergetic metrics. Exergy Loss Index below 50% is considered as good performance and it is suggested to be controlled below 80%. Finally, the contributions as well as the limitations of new proposed metrics are discussed when used in design and operation stages. It shows that introducing new exergetic metrics to the existing evaluation system is a more comprehensive way to evaluate the thermal management in typical DCs.

Functional Performance Evaluation of a Novel Thermal Environment Sensor Array

Abstract. The thermal environment (TE) inside livestock and poultry facilities has a substantial impact on animal growth performance and facility energy usage; therefore, the TE must be quantified correctly to maintain the optimal TE that maximizes feed efficiency and consumes minimal resources. To achieve this goal, a TE sensor array (TESA) and accompanying data acquisition system were previously developed to measure dry-bulb temperature (tdb), black globe temperature, airspeed, and relative humidity (RH). While measurement of each parameter is useful individually, it is more informative when they are combined to estimate and assess the total impact that the TE has on an animal. Hence, the objectives of this study were to (1) design, construct, and commission a TE simulation system, named the Animal Thermal Environment Replication and Measurement System (AThERMS), and (2) compare total sensible heat loss estimated by TESA to a reference ideal temperature source (ITS) when subjected to different TE conditions inside AThERMS. AThERMS is a 1.04 × 1.17 × 1.04 m chamber inside a large insulated enclosure in which air supplied by an air handling unit provides unique combinations of tdb, RH, and airspeed while independently controlling chamber surface temperature (ts). Commissioning of AThERMS included qualitative (smoke visualization) and quantitative (three-dimensional traverse) velocity characterizations in the central region of the chamber and verification of similar and stable ts for all six surfaces. Analysis of velocity contours at three nominal flow rates indicated steady patterns, and at three nominal ts values (13°C, 23°C, and 33°C) during 2 h steady-state operation, the maximum average difference between any two of the six surface ts values was 0.26°C. The TESA was then suspended in AThERMS adjacent to the ITS (15.24 cm diameter black copper sphere with a heater immersed in water). The ITS and TESA were subjected to two nominal airspeeds (~0.5 and 2.0 m s-1) at three nominal tdb values (17°C, 25°C, and 33°C) with a mean radiant temperature approximately equal to the nominal tdb. Total heat loss was estimated from heat transfer theory with TESA measurements as inputs and compared to the measured root mean square power required to maintain a constant water temperature in the ITS. Overall, predicted total heat loss underestimated measured power for all six tests. Future work needs to improve the measurement accuracy at low total heat losses. AThERMS can be used to simulate different TEs that an animal may experience and provide steady reference conditions to verify TE measurements. The TESA is a novel and effective tool for understanding the TE distribution and estimating total heat loss. Keywords: Black globe, Data acquisition, Swine, Ventilation.

Influence of urbanization on the thermal environment of meteorological station: Satellite-observed evidence

In this paper, five national meteorological stations in Anhui province are taken as typical examples to explore the effects of local urbanization on their thermal environment by using Landsat data from 1990 to 2010. Satellite-based land use/land cover (LULC), land surface temperature (LST), normalized difference vegetation index (NDVI) are used to investigate the effects. The study shows that LULC around meteorological stations changed significantly due to urban expansion. Fast urbanization is the main factor that affects the spatial-temporal distribution of thermal environment around meteorological stations. Moreover, the normalized LST and NDVI exhibit strong inverse correlations around meteorological stations, so the variability of LST can be monitored through evaluating the variability of NDVI. In addition, station-relocation plays an important role in improving representativeness of thermal environment. Notably, the environment representativeness was improved, but when using the data from the station to study climate change, the relocation-induced inhomogeneous data should be considered and adjusted. Consequently, controlling the scale and layout of the urban buildings and constructions around meteorological stations is an effective method to ameliorate observational thermal environment and to improve regional representativeness of station observation. The present work provides observational evidences that high resolution Landsat images can be used to evaluate the thermal environment of meteorological stations.

市街化空間の熱的環境に関する研究 : その 2・東京における熱的環境調査

In the Tokyo district, there are 14 observatories evenly to make hourly meteorological observations. By recording these meteorological data on magnetic tapes at intervals of one hour throughout the year and analyzing them, it is thought possible to grasp positive thermal environments in urbanized areas. This paper consists of outlines of thermal environments in the Tokyo district, analyses of correlations between various meteorological factors and temperature and humidity distributions, analyses of correlations between areas of thermal environments and preparation of widearea thermal environment distribution maps. Temperature distribution are closely related to humidity distributions, and the intensity of these distributions is approximate proportional to the quantity of potential evapotranspiration. A sort of probability theory was used to draw distribution maps. At the center of Tokyo, there are rather many green tracts comparatively, therefore, high temperature areas appear around the center of the urbanized area in summer time, and the large heat-island phenomena are seen at the center of the city in winter time.