scholarly journals Introduction to the Dynamics of Heat Transfer in Buildings

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6469
Author(s):  
Bożena Babiarz ◽  
Władysław Szymański
Keyword(s):  
Heat Transfer ◽  
Air Temperature ◽  
Thermal Inertia ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Point Of View ◽  
Thermal Dynamics ◽  
Annual Cycles ◽  
Gains And Losses ◽  
Over Time

Changing climatic conditions cause the variability of the parameters of the building’s surroundings, which in turn causes both the gains and losses of heat to change over time. There is variability in both daily and annual cycles. Meeting the requirements of thermal comfort in rooms requires maintaining the required parameters, including constant temperature. Heat gains and losses must be balanced, and this balance is ensured through appropriate heating systems. At the same time, the above means that the demand for heating buildings is not constant but depends on external weather conditions and the energy efficiency of the building. This, in turn, affects the thermal inertia, causing changes in the partition temperature to occur slower than the changes in air temperature. Therefore, the amplitude of the heating power changes is not proportional to the amplitude of the outside air temperature change. The paper presents an example of the analysis of thermal dynamics in buildings. Various aspects of heat transfer in the building were investigated taking into account the transient conditions. The variability of temperature over time at different depths of the partition was analysed, showing the results graphically. The periodic variability of the outside air temperature and the intensity of solar radiation were described by the Fourier series. Moreover, the article shows the influence of the thermal insulation thickness of the external wall on the annual amplitude of temperature changes and on the duration of the heating season, which is important from the point of view of optimization.

Experimental Modeling of Air Temperature and Velocity Distribution in an Engine Compartment

2006 ◽  
Author(s):  
A. A. Mozafari ◽  
M. H. Saidi ◽  
J. Neyestani ◽  
A. E. Sany
Keyword(s):  
Heat Transfer ◽  
Velocity Distribution ◽  
Air Temperature ◽  
Gasoline Engine ◽  
Point Of View ◽  
Vehicle Body ◽  
Air Distribution ◽  
Wind Effect ◽  
Engine Compartment ◽  
Air Velocity

Investigation of air distribution and wind effect on a vehicle body from the point of view of underhood heat transfer effect and proper positioning of vehicle elements such cooler, condenser and engine configuration is an important area for engine researchers and manufacturers as well. In this research, the effect of air velocity distribution and wind effect around a vehicle is simulated and temperature and velocity distribution around engine block which is influenced by the wind effect is investigated. Thermal investigation of the engine compartment components is performed using results of underhood air temperature and velocity distribution. The heat transfer from engine surface is calculated from the engine energy balance in which their input data are obtained from a comprehensive experimental study on a four cylinder gasoline engine.

scholarly journals Identification of solar radiation effect on climatic indicators of the territory of Ukraine

2018 ◽  
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Air Temperature ◽  
Temperature Regime ◽  
Atmospheric Pressure ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Practical Significance ◽  
Statistical Dependence ◽  
Physical Processes

Formulation of the problem. Understanding that solar energy is the main source of the majority of biological, chemical and physical processes on Earth, investigation of its influence on different climatic fields allows us to define the features of its space and hour fluctuations. To define radiation and temperature regime of the territory it is necessary to determine climatic features of the spreading surface, which absorbs and will transform solar energy. Considering the fact that modern climatic changes and their consequences cover all components of the system, today there is a problem of their further study for comprehension of atmospheric processes, modeling weather conditions on different territories depending on the properties. The purpose of the article is to determine interrelations between indexes of solar radiation (the Wolf's number) and air temperature, atmospheric pressure on the territory of Ukraine during 1965-2015, their change in space and time. Methods. Correlative method is one of the main methods of a statistical analysis which allows us to receive correlation coefficients of solar radiation variability indexes, air temperature, atmospheric pressure on the territory of the research. This technique estimates the extent of solar radiation influence on temperature regime of the territory and distribution of atmospheric pressure. Results. Coefficients of correlation, which characterize variability of solar radiation indexes, air temperature and atmospheric pressure on the explored territory have been received by means of statistical correlation analysis method. This technique allows us to estimate the degree and nature of solar radiation influence on a temperature regime of the territory and distribution of atmospheric pressure. It has been defined that direct correlative connection between indexes of solar radiation is characteristic of air temperature and atmospheric pressure fields. Significant statistical dependence between incoming solar radiation on the territory of Ukraine and atmospheric pressure has been noted during the spring and autumn periods mainly at the majority of stations. Between indexes of solar radiation and air temperature the inverse correlative connection in winter will be transformed to a direct connection during the spring and summer periods. Scientific novelty and practical significance. Physical processes, which happen in the atmosphere, are characterized by complex interrelations. For further research it is important to define solar radiation value and the extent of influence on climatic conditions.

Simplified Procedure for Prediction of Asphalt Pavement Subsurface Temperatures Based on Heat Transfer Theories

1997 ◽  
Vol 1568 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Lisheng Shao ◽  
Sun Woo Park ◽  
Y. Richard Kim
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Air Temperature ◽  
Asphalt Pavement ◽  
Prediction Method ◽  
Point Of View ◽  
Temperature History ◽  
Climatic Regions ◽  
Simplified Procedure ◽  
Subsurface Temperatures

Surface deflection measurements and backcalculation of layer moduli in flexible pavements are significantly affected by the temperature of the asphalt concrete (AC) layer. Correction of deflections or backcalculated moduli to a reference temperature requires determination of an effective temperature of the AC layer. For routine deflection testing and analysis in state highway agencies, it is preferable, from a practical point of view, to use a nondestructive prediction method for determining the effective AC layer temperature instead of measuring the temperature directly from a small hole drilled into the AC layer. A simplified procedure to predict asphalt pavement subsurface temperatures is presented. The procedure is based on fundamental principles of heat transfer and uses the surface temperature history since yesterday morning to predict the AC layer mid-depth temperature at the time of falling weight deflectometer (FWD) testing today. The surface temperature history is determined using yesterday’s maximum air temperature and cloud condition, the minimum air temperature of today’s morning, and surface temperatures measured during FWD tests. FWD tests and temperature measurements have been conducted on seven pavement sections with varying structural designs located in three different climatic regions of North Carolina. The field temperature records from these pavements have provided values of pavement thermal parameters and coefficients in temperature functions that are needed in the prediction procedure. A set of verification results are presented using examples with different climatic regions, changing AC layer thicknesses, and varying weather patterns in different seasons.

PRODUCTIVITY ASSESSMENT OF SUNFLOWER HYBRIDS IN THE FOREST-STEPPE CONDITIONS OF THE MIDDLE VOLGA REGION

2020 ◽  
Vol 15 (8) ◽  
pp. 1094-1104
Author(s):  
E.V. Zheryakov ◽  
◽  
A.A. Novokhvatskiy ◽  
Keyword(s):  
Weather Conditions ◽  
Industrial Sector ◽  
Climatic Conditions ◽  
Point Of View ◽  
Theoretical Research ◽  
Forest Steppe ◽  
Middle Volga Region ◽  
Early Season ◽  
Environmental Testing ◽  
Early Maturing

Sunflower production is an important task for the country’s agro-industrial sector. Environmental testing of promising sunflower hybrids in specific soil and climatic conditions is important, both from the point of view of theoretical research and practice. The studies were carried out on chernozem soils in the conditions of the Penza region in 2016-2019. The article presents the results of a comparative assessment of various sunflower hybrids in terms of productivity. The influence of weather conditions on the duration of the main phases in growth and development of various sunflower hybrids, and photosynthetic activity of crops was studied. When growing sunflower in 2016, biological ripeness occurred in early-maturing hybrids on August 27, in the mid-early hybrid 10 days later, and mid-season hybrids on September 19. In 2017, the biological ripeness of all hybrids came later compared to 2016. In 2018, biological ripeness came later than in 2016 and 2017. In 2019, early-maturing hybrids had biological ripeness on August 26 ... 28, mid-early September 4, mid-season September 20. Studies have established the peculiarities of the sunflower achenes formation depending on the hybrid: Neoma hybrid achenes were larger in comparison with the achenes of other hybrids, and the smallest achenes were in the early-season Amis hybrid. The mass of 1000 achenes in all hybrids was greatest in the marginal part of the basket. The highest yield of oilseeds on average over the years of research was obtained for the mid-season Neoma hybrid. According to the research results, the most productive and stable hybrids in the Penza region were identified, having an adaptability coefficient of more than one. The highest oil content in seeds on average over the years of research was obtained when growing an early-season Fortimi hybrid.

Modeling of air temperatures using a combination of TBATS and SVM models for various climatic locations in Europe

2020 ◽  
Author(s):  
Magdalena Gos ◽  
Piotr Baranowski ◽  
Jaromir Krzyszczak ◽  
Małgorzata Murat ◽  
Iwona Malinowska
Keyword(s):  
Time Series ◽  
State Space ◽  
Air Temperature ◽  
Weather Conditions ◽  
Exponential Smoothing ◽  
Climatic Conditions ◽  
State Space Models ◽  
Temperate Climate ◽  
Support Vector ◽  
Air Temperatures

<p>By modelling and forecasting  of meteorological  time  series it is possible to  improve   understanding  of  the  weather dynamics and fluctuations as a result of climate change . The most frequently used forecasting models are exponential smoothing, ARIMA models (Box and Jenkins, 1970), state-space models (Harvey, 1989) and innovations State Space Models (Hyndman et al., 2008).</p><p>The aim of this study was to check the effectiveness of the coupled TBATS and Support Vector Machines (SVM) model, supplied with some measured meteorological quantities to forecast air temperature for six years for four climatic localizations in Europe. The study was calculated from northern (Jokioinen in Finland), central (Dikopshof located in the west part of Germany and Nossen in the south part of Germany) and southern (Lleida in Spain) Europe to present different climatic conditions. Jokioinen city has a subarctic climate that has severe winters, with cool and short summers and strong seasonality. Lleida has a semi-arid climate with Mediterranean. Dikopshof represents maritime temperate climate. There are significant precipitation throughout the year in Dikopshof and Nossen. In the study we study on air temperature dataset collected on a daily basis from January 1st 1980 to December 31st 2010 (11322 days).</p><p>For all the studied sites coupled TBATS/SVM models occurred to be effective in predicting air temperature courses, giving an improved precision (up to 25%) in forecasting of the seasonality and local temperature variations, compared to pure SVM or TBATS modelling. The precision of prediction of the maximum and minimum air temperatures strongly depended on the dynamics of the weather conditions, and varied for different climatic zones.</p><p>This study has been partly financed from the funds of the Polish National Centre for Research and Development in frame of the project: MSINiN, contract number: BIOSTRATEG3/343547/8/NCBR/2017.</p><p> </p><p>Reference to a journal publication:</p><p>BOX, G.E.P. – Jenkins, G. 1970. Time Series Analysis: forecasting and control. Holden-Day, p. 20-31.</p><p>HARVEY A. 1989. Forecasting Structural Time Series Model and the Kalman Filter. New York, Cambridge University press., p. 32-41.</p><p>HYNDMAN, R.J. – KOEHLER, A.B. – ORD, J.K. – SNYDER, R.D. 2008. Forecasting with Exponential Smoothing: The State Space Approach. Springer-Verlag, p. 50-62.</p>

scholarly journals Justification of permissible deviation of performance of technological operations in process of feeding animals

2020 ◽  
Vol 11 (3) ◽  
pp. 89-93
Author(s):  
V. S. Khmelovskyi ◽  
Keyword(s):  
Mathematical Modeling ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Point Of View ◽  
Maximum Deviation ◽  
Feed Mixture ◽  
Preparation Time ◽  
Technological Processes ◽  
Maximum Duration ◽  
Permissible Deviation

The issues of implementation of technological processes of preparation and distribution of feed mixture, according to the schedule of technological operations of the livestock complex are considered. The processes of preparation and distribution of the feed mixture are largely influenced by natural and climatic conditions, and accordingly, the daily performance of technological operations has certain deviations in time according to the routine of the livestock complex. One of the features of the processes of preparation and distribution of the feed mixture is the movement of the feed preparation unit between the feed storages under various weather conditions that affect the speed of the unit. Based on the results of evaluating the delay in the execution of technological operations in the preparation and distribution of the feed mixture, using the method of mathematical modeling, the influence on the productivity of animals was determined, justified optimal, from the point of view of zootechnical requirements, delay intervals in the execution of operations in which animals do not lose productivity and ways of their compensation are proposed when performing technological processes. The results of literary studies indicate that a delay in the distribution of the feed mixture for more than 10 minutes leads to a rapid increase in the loss of milk production of animals, and the time for their recovery is about 4-5 days. On the basis of the studies carried out, it has been proved that it is possible to compensate for the delays in the execution of technological operations of the preparation and distribution of the feed mixture by the time that falls on the mixing of the feed components, and can be partially or completely reduced, (provided that transportation operations are performed simultaneously, from the last load of the feed component and mixing). The calculation of the maximum deviation in the execution of the processes of preparation and distribution of the feed mixture, carried out by the method of mathematical modeling, determined that the maximum duration of the delay, taking into account the time to which the animals do not react, can be 22-27% of the preparation time of the feed mixture.

Trends in the Phenology of Climber Roses under Changing Climate Conditions in Mazovia Lowland in Central Europe

2021 ◽  
Author(s):  
Marta Monder
Keyword(s):  
Central Europe ◽  
Air Temperature ◽  
Ornamental Plants ◽  
Ground Level ◽  
Weather Conditions ◽  
Frost Damage ◽  
Growth Conditions ◽  
Climatic Conditions ◽  
Climate Conditions ◽  
Urban Green Spaces

The genetic pool of valuable old ornamental cultivars and their in situ maintenance may be threated by climate change. Meanwhile, the ornamental plants like roses make up an important share of both gardens and urban green spaces, where they are particularly vulnerable to multistress growth conditions. The aim of this research was to evaluate the effect of changing climatic conditions on growth and flowering of 11 historic climber roses through long-term studies (2000-2017) conducted in Central Europe. The evaluation of plants consisted of assessment of frost damage and the timing of early phenological stages (starting of bud break, leaf unfolding) as well as gathering data on beginning, fullness and end of flowering and its abundance. Frost damage was not recorded in any year only in ‘Mme Plantier’, and did not occur for any cultivar after the winter in the years 2007, 2008, and 2014. Only a little damage to one-year shoots was recorded after the winter in the years 2015-2017. Frost damage to ‘Alberic Barbier’, ‘Albertine’, ‘Chaplin's Pink Climber’, ‘Orange Triumph clg’ and ‘Venusta Pendula’ led to pruning to ground level in every year excluding those listed above. Frost damage of once blooming roses limited their flowering; however, the many-year data-sets showed a trend for decreased frost damage and improved abundance of flowering, and these results can be interpreted as a response to the increase of average air temperature. The timing of bud breaking and leaf development in all climber roses was strictly correlated with average air temperature in the dormancy period. The reactions of climber roses to weather conditions confirmed the influence of climatic changes on ornamental crop plants in Central Europe, introducing the potential possibility for the wider application of climber roses, but without certainty of flowering every year.

Thermofluidynamic Model and Comparative Analysis of Parabolic Trough Collectors Using Oil, Water/Steam, or Molten Salt as Heat Transfer Fluids

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
M. J. Montes ◽  
A. Abánades ◽  
J. M. Martínez-Val
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Point Of View ◽  
Heat Transfer Fluid ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Water Steam ◽  
Temperature And Pressure ◽  
Energy Gains ◽  
Gains And Losses

This paper describes the development and use of a thermofluidynamic model for parabolic trough collectors, specifically suited for carrying out systematic calculations on different design options. The model is based on detailed energy balances, and it has been applied to evaluate collector thermal performances with different working fluids: oil, molten salt, or water/steam. For each heat transfer fluid technology, four parameters have been analyzed: collector length, absorber tube diameter, working temperature, and pressure. The influence of these factors has been studied from the point of view of heat loss, pressure drop, energy, and exergy efficiencies. Exergy is considered the suitable magnitude to guide any optimization process in this field, because it accounts for all relevant energy gains and losses, characterized by their corresponding temperature and pressure. Preliminary conclusions point out that direct steam generation is more efficient than oil and molten salt systems.

scholarly journals SEED REPRODUCTION OF PHLOX PANICULATA L. IN PERM REGION CLIMATIC CONDITIONS

2020 ◽  
pp. 103-108
Author(s):  
S. A. Shumikhin ◽  
◽  
M. A. Chertkova ◽  
L. V. Aksenova ◽  
◽  
...  
Keyword(s):  
Air Temperature ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Seed Productivity ◽  
Large Variability ◽  
Phlox Paniculata ◽  
Insect Pollinators ◽  
Complex Hybrid ◽  
Seed Propagation ◽  
Perm Region

During 2015-2018 in the conditions of the Perm region, the seed productivity of 6 varieties Phlox paniculata L. has been studied. The effectiveness of seed production and the success of seed propagation of the phlox depend on the weather conditions strongly, in particular on the air temperature and the amount of precipitation at the corresponding stages of plant development. This is determined by the activity of insect pollinators and effectiveness of pollination. In addition, the large variability of the studied indices in different flox cultivars is probably due to their complex hybrid nature, which reduces their reproductive abilities to varying degrees.

scholarly journals Adaptive phenological response of autochthonous grape varieties to changes in weather and climatic conditions in the South of Russia

2020 ◽  
pp. 210-215
Author(s):  
Валерий Семенович Петров ◽  
Анна Александровна Марморштейн ◽  
Анна Александровна Лукьянова ◽  
Александр Григорьевич Коваленко ◽  
Владимир Александрович Волынкин
Keyword(s):  
Field Experiment ◽  
Air Temperature ◽  
Adaptive Response ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Stationary Field ◽  
The South ◽  
Beginning Of Flowering ◽  
Grape Varieties

В длительном стационарном полевом опыте на ампелографической коллекции (г.-к. Анапа) установлен тренд устойчивого влияния изменений погодных условий юга России на адаптивную фенологическую реакцию автохтонных сортов винограда Плечистик, Сибирьковый, Цимлянский черный. При повышении температуры воздуха на 1,2 - 5,0 °С период от распускания почек до полной физиологической зрелости ягод винограда у сорта Плечистик уменьшился на 22, Сибирьковый - 30, Цимлянский черный - 25 дней. Уменьшение произошло за счет смещения сроков и продолжительности фаз вегетаций. У сорта Плечистик вегетация от начала распускания глазков до начала цветения уменьшилась на 10, от начала цветения до начала созревания ягод на 11, от начала созревания до полной физиологической зрелости ягод на 23 дня, у сорта Сибирьковый соответственно на 8, 9 и 13 дней, у сорта Цимлянский черный на 7, 5 и 23 дня. Начало распускания глазков сместилось в более поздние сроки у сорта Плечистик на 1 день, Сибирьковый на 5 дней, Цимлянский черный на 2 дня. Начало цветения сместилось в ранние сроки у сорта Плечистик на 9 дней, Сибирьковый на 3 дня, Цимлянский черный на 5 дней. Начало созревания ягод винограда у сорта Плечистик сдвинулось на 1 день в поздний срок, Сибирьковый на 12 дней и Цимлянский черный на 3 дня в ранние сроки. Полная физиологическая зрелость ягод сместилась в ранние сроки у сорта Плечистик на 21 день, Сибирьковый на 25 дней и Цимлянский черный на 23 дня. При положительной адаптивной реакции на повышение температуры воздуха у сортов сохранились без изменений ростовые и продукционные процессы. In a long-term stationary field experiment on the ampelographic collection (Anapa), a trend for the stable influence of changes in weather conditions in the South of Russia on the adaptive phenological reaction of autochthonous grape varieties ‘Pletchistik’, ‘Sibirkovy’, ‘Tsimlyansky Cherny’ was established. With an increase in air temperature by 1.2 - 5.0 °С, the period from budbreak to physiological ripeness of the ‘Pletchistik’ variety decreased by 22, ‘Sibirkovy’ - 30, ‘Tsimlyansky Cherny’ - 25 days. The decrease was due to the shift in the timing and duration of vegetative stages. For ‘Pletchistik’ variety, the period from budbreak to flowering decreased by 10, from flowering to veraison by 11, from veraison to physiological ripeness by 23 days; for ‘Sibirkovy’ variety, by 8, 9 and 13 days respectively; for the variety ‘Tsimlyansky Cherny’ by 7, 5 and 23 days. The beginning of budbreak shifted to later dates: for ‘Pletchistik’ variety by 1 day, for ‘Sibirkovy’ by 5 days, for ‘Tsimlyansky Cherny’ by 2 days. The beginning of flowering shifted to earlier dates: for ‘Pletchistik’ variety by 9 days, for ‘Sibirkovy’ by 3 days, for ‘Tsimlyansky Cherny’ by 5 days. The beginning of veraison for ‘Pletchistik’ variety shifted by 1 day later, for ‘Sibirkovy’ by 12 days and for ‘Tsimlyansky Cherny’ by 3 days earlier. The beginning of full physiological ripeness shifted earlier for all varieties: ‘Pletchistik’ by 21 days, ‘Sibirkovy’ by 25 days and ‘Tsimlyansky Cherny’ by 23 days. With a positive adaptive response to an increase in air temperature, the growth and productional processes of varieties remained without changes.

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