The Effect of Thermal Mass on Thermal Transmission Loads

2007 ◽  
Author(s):  
Robert B. Gilbert ◽  
Kelly Kissock
Keyword(s):  
Air Temperature ◽  
Thermal Load ◽  
Weather Conditions ◽  
Weather Data ◽  
Thermal Mass ◽  
Load Reduction ◽  
Difference Model ◽  
Data Files ◽  
The Mean ◽  
Sinusoidal Function

A finite-difference model is used to simulate the effects of thermal mass on thermal load. A sinusoidal function is used to simulate the exterior air temperature. The interior air temperature set point remains constant. The mechanism by which thermal mass affects thermal load is described. Equations are given to calculate thermal load as a function of the exterior air temperature amplitude, the temperature above and below the mean temperature. Equations are given to calculate the minimum thermal load resulting from thermal mass and therefore the maximum thermal load reduction with thermal mass. Equations and methods are given to calculate the minimum thermal load resulting from thermal mass from weather data files, TMY or TMY2 files. A design equation is given as a guideline to determine the amount of thermal mass required to reduce the thermal load with given weather conditions.

The Effects of Thermal Mass and Phase Change Material on a Buildings’ Thermal Load

2009 ◽  
Author(s):  
Robert B. Gilbert
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Thermal Load ◽  
Thermal Mass ◽  
Load Reduction ◽  
Difference Model ◽  
Maximum Reduction ◽  
Material Equations ◽  
Change Material ◽  
Sinusoidal Function

A finite-difference model is used to simulate the effects of thermal mass and phase change material on thermal transmission through a building’s envelope wall. The exterior temperature is simulated by a sinusoidal function. The inside temperature is held constant. A comparison is given between the effects of thermal mass and phase change material. The maximum reduction in thermal load and required conditions is given for both thermal mass and phase change material. Equations are given for the maximum thermal load reduction as a function of the inside and outside temperature. Equations are also given which treat the thermal mass as a lumped capacitance and the expected error as a function of the amount of thermal mass. The conditions under which the addition of thermal mass and/or phase change material will result in a reduction of thermal load is given.

IV.—A Note on the Secular Changes of Rock Temperature on the Calton Hill

1932 ◽  
Vol 51 ◽  
pp. 19-24
Author(s):  
F. J. W. Whipple
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Weather Conditions ◽  
Temperature Variations ◽  
Secular Changes ◽  
Rock Temperature ◽  
The Mean

1. The observations of rock temperature on the Calton Hill have recently been analysed by Mr R. W. Wrigley, with a view to the discovery of changes going on gradually and independent of weather conditions. Mr Wrigley took groups of years, such that the mean air temperature was the same for each group, and found the mean rock temperature for like periods. He trusted that in this way he would be able “to get rid of the surface temperature variations.” The result of the calculations was that for different periods in which the mean air temperature was the same the temperature of the rock might vary by half a degree Fahrenheit. The rock temperature had a maximum about 1856, fell until 1892, and rose after that date.

Weather factors affecting the development of maize from sowing to flowering

1972 ◽  
Vol 78 (2) ◽  
pp. 325-331 ◽  
Author(s):  
M. N. Hough
Keyword(s):  
Soil Moisture ◽  
Correlation Analysis ◽  
Linear Correlation ◽  
Weather Conditions ◽  
Weather Data ◽  
Weather Factors ◽  
Mean Values ◽  
Rate Of Development ◽  
Linear Correlation Analysis ◽  
The Mean

SUMMARYThe phenological development from sowing to flowering of the eaxly maize hybrid INRA 200 is related to the weather conditions. Plot trial data from Wytham, near Oxford, England, and weather information from that and nearby sites formed the basic data.The mean rate of development per day from sowing to emergence is related by linear correlation analysis to the mean values of soil temperature at 5 cm depth and soil moisture deficit. A range of temperature thresholds for emergence development exist, which depend upon the soil moisture, and which differ from the true physiological threshold.Between omergence and flowering the mean rate of development per day is related by linear correlation analysis to mean air temperature, solar radiation and potential transpiration estimated from weather data. All correlations are significant, but the parameters which combine radiation and temperature are statistically better.

scholarly journals Moisture content of cereals at harvesting time by comparing microclimate values and standard weather data

1993 ◽  
Vol 41 (3) ◽  
pp. 167-178
Author(s):  
A.J. Atzema
Keyword(s):  
Moisture Content ◽  
Surface Temperature ◽  
Air Temperature ◽  
Weather Conditions ◽  
Dew Point ◽  
Weather Data ◽  
Daily Cycle ◽  
The Difference ◽  
High Equilibrium ◽  
Screen House

The moisture content of wheat and barley together with the weather elements were measured at 3 different experimental sites in the Netherlands in 1990-91. The difference in the dew point temperature in the screen[house] and in the field was small. However, the differences between air temperature in the screen and those at different heights in wheat and in barley stands were considerable. In daytime the surface temperature of barley was higher than that of wheat under the same weather conditions as a result of a higher absorbtion coefficient. Both for wheat and barley, the maximum difference between the calculated moisture content was 0.5%, using the air temperature at 1.5 m height from the nearest standard weather station and the surface temperature of the spikes. Barley had a greater daily cycle in the moisture content of the grains than wheat as a result of a high equilibrium moisture content during the night and a low one in daytime.

Annual daylight glare evaluation: Impact of weather file selection

2016 ◽  
Vol 50 (3) ◽  
pp. 446-455 ◽  
Author(s):  
Q-G Deng ◽  
G-Y Cao ◽  
Z-C Liu ◽  
Z-S Wang ◽  
Y Yang ◽  
...  
Keyword(s):  
Time Distribution ◽  
Weather Conditions ◽  
Extreme Weather ◽  
The Other ◽  
Weather Data ◽  
Energy Calculations ◽  
Data Files ◽  
The Impact ◽  
Interior Environment

This paper illustrates the results of daylight glare simulations of a simple office carried out using five different five weather data files (Chinese typical year weather, CSWD(C), CSWD(A), international weather for energy calculations and Meteonorm), for three Chinese locations (Beijing, Shanghai and Guangzhou). The aim is to analyse the impact of choosing one weather file or the other on the prediction of daylight glare in the interior environment. The results show that using the Chinese typical year weather and CSWD(C) files can make a better prediction of the time distribution of daylight glare than the others. Analysis of the total amount of daylight glare leads to the conclusion that the Chinese typical year weather file should be recommended when considering extreme weather conditions and the CSWD(C) or Meteonorm files should be recommended in normal weather conditions.

scholarly journals Computational Modeling of the Thermal Behavior of a Greenhouse

2021 ◽  
Vol 11 (24) ◽  
pp. 11816
Author(s):  
Bruno Lebre ◽  
Pedro D. Silva ◽  
Luís C. Pires ◽  
Pedro D. Gaspar
Keyword(s):  
Thermal Behavior ◽  
Air Temperature ◽  
Agricultural Sector ◽  
Computational Simulation ◽  
Double Cover ◽  
Operating Conditions ◽  
Weather Data ◽  
Thermal Mass ◽  
Airflow Rate ◽  
The North

The need for production of all kinds of crops in high quantities and over the entire year makes the agricultural sector one of the major energy consumers. The optimization of this consumption is essential to guarantee its sustainability. The implementation of greenhouses is a strategy that allows assurance of production needs and possesses large optimization potential for the process. This article studies different greenhouse structures by computational simulation using EnergyPlus and DesignBuilder. First, a comparison was performed between the computational results and the measured values from a greenhouse prototype at different operating conditions. Overall, the comparison shows that the computational tool can provide a reasonable prediction of the greenhouse thermal behavior, depending on the differences between the weather data modeled and observed. An outdoor air temperature difference of 16 °C can cause a difference of about 10 °C between the air temperature predicted and measured inside the greenhouse. Subsequently, a selected set of case studies was developed in order to quantify their influence on the thermal performance of the greenhouse, namely: the greenhouse configuration and orientation; the variation of indoor air renewal; changes to the characteristics of the roof; the effect of the thermal mass of the walls; and location of the greenhouse. The results show that a correct greenhouse orientation, together with a polyethylene double cover with a 13 mm air layer, a granite wall of 40 cm thickness on the north wall, and variable airflow rate, may lead to a reduction of the greenhouse energy consumption by 57%, if the greenhouse is located in Lisbon, or by 43%, if it is located in Ostersund, during the hottest months of the heating season.

Effects of climatic elements on Campylobacter-contaminated chicken products in Japan

2011 ◽  
Vol 140 (6) ◽  
pp. 991-996 ◽  
Author(s):  
K. ISHIHARA ◽  
R. TAKAHASHI ◽  
M. ANDOH ◽  
K. MAKITA ◽  
S. KAMIJI ◽  
...  
Keyword(s):  
Short Duration ◽  
Air Temperature ◽  
Sunshine Duration ◽  
Climatic Conditions ◽  
Weather Data ◽  
High Humidity ◽  
Air Temperatures ◽  
The Mean ◽  
Climatic Elements

SUMMARYJapanese weather data for areas that produced Campylobacter spp.-positive chicken products were compared with those for areas producing negative samples. Regarding samples produced during the period of rising temperature (spring and summer), the mean weekly air temperatures for Campylobacter-positive samples were higher than those for negative samples for the period of the week in which the samples were purchased (18·7°C vs. 13·1°C, P=0·006) to a 12-week lag (12 weeks before purchasing samples; 7·9°C vs. 3·4°C, P=0·009). Significant differences in weekly mean minimum humidity and sunshine duration per day were also observed for 1- and 2-week lag periods. We postulated that the high air temperature, high humidity and short duration of sunshine for the chicken-rearing period increased Campylobacter colonization in chickens during the period of rising temperature. Consequently, the number of Campylobacter-contaminated chicken products on the market in Japan may fluctuate because of the climatic conditions to which reared chickens are exposed.

scholarly journals Performance Evaluation of Neural Network-Based Short-Term Solar Irradiation Forecasts

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3030
Author(s):  
Simon Liebermann ◽  
Jung-Sup Um ◽  
YoungSeok Hwang ◽  
Stephan Schlüter
Keyword(s):  
Neural Network ◽  
Goodness Of Fit ◽  
Renewable Energy Sources ◽  
Weather Conditions ◽  
Solar Irradiation ◽  
Weather Data ◽  
Short Term ◽  
Climate Conditions ◽  
Lstm Network ◽  
The Time Domain

Due to the globally increasing share of renewable energy sources like wind and solar power, precise forecasts for weather data are becoming more and more important. To compute such forecasts numerous authors apply neural networks (NN), whereby models became ever more complex recently. Using solar irradiation as an example, we verify if this additional complexity is required in terms of forecasting precision. Different NN models, namely the long-short term (LSTM) neural network, a convolutional neural network (CNN), and combinations of both are benchmarked against each other. The naive forecast is included as a baseline. Various locations across Europe are tested to analyze the models’ performance under different climate conditions. Forecasts up to 24 h in advance are generated and compared using different goodness of fit (GoF) measures. Besides, errors are analyzed in the time domain. As expected, the error of all models increases with rising forecasting horizon. Over all test stations it shows that combining an LSTM network with a CNN yields the best performance. However, regarding the chosen GoF measures, differences to the alternative approaches are fairly small. The hybrid model’s advantage lies not in the improved GoF but in its versatility: contrary to an LSTM or a CNN, it produces good results under all tested weather conditions.

scholarly journals Potential Fertilization Capacity of Two Grapevine Varieties: Effects on Agricultural Production in Designation of Origin Areas in the Northwestern Iberian Peninsula

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 961
Author(s):  
J. Antonio Cortiñas Rodríguez ◽  
María Fernández-González ◽  
Estefanía González-Fernández ◽  
Rosa A. Vázquez-Ruiz ◽  
F. Javier Rodríguez-Rajo ◽  
...  
Keyword(s):  
Airborne Pollen ◽  
Germination Rate ◽  
Pollen Viability ◽  
Weather Conditions ◽  
Triphenyl Tetrazolium Chloride ◽  
Tetrazolium Chloride ◽  
The Mean ◽  
Study Sites ◽  
Fertilization Capacity

In the present study, we analyzed the main parameters related with the potential fertilization ability of two grapevine varieties, Godello and Mencía, during the years 2017 and 2018. The research was carried out in two vineyards of the Galician winegrowing Designation of Origin areas of Ribeiro and Ribeira Sacra. Ten vines of each variety were selected for bunch and flower counting, pollen calculations, pollen viability studies by means of aceto-carmine (AC) stain and 2, 3, 5-triphenyl tetrazolium chloride (TTC) methods, and the determination of their germination rate. In all vineyards the 50% fruitset was reached, except for Godello in Cenlle during 2017. The mean coulure value was higher for Godello (40.5%) than for Mencía (31%). Analyzing the pollen production per plant and airborne pollen levels, we observed important discordances between them, which can be due to the influence of weather conditions and be related with self-pollination processes. We found important differences on pollen viability depending on the applied method and variety, with higher values for the AC method than the TTC for both varieties in all study plots, and higher values for Mencía variety than Godello. Regarding germination rates, we observed a marked reduction in 2017 with respect to 2018, in all study sites and for both varieties. The analyzed parameters were useful to explain the different productive abilities of Godello and Mencía varieties in the two studied bioclimatic regions of Ribeiro and Ribeira Sacra.

scholarly journals Advanced Flight Planning and the Benefit of In-Flight Aircraft Trajectory Optimization

2021 ◽  
Vol 13 (3) ◽  
pp. 1383
Author(s):  
Judith Rosenow ◽  
Martin Lindner ◽  
Joachim Scheiderer
Keyword(s):  
New York ◽  
Traffic Control ◽  
Traffic Management ◽  
Trajectory Optimization ◽  
Service Providers ◽  
Weather Conditions ◽  
Air Traffic ◽  
Weather Data ◽  
Weather Forecasts ◽  
Aircraft Trajectory

The implementation of Trajectory-Based Operations, invented by the Single European Sky Air Traffic Management Research program SESAR, enables airlines to fly along optimized waypoint-less trajectories and accordingly to significantly increase the sustainability of the air transport system in a business with increasing environmental awareness. However, unsteady weather conditions and uncertain weather forecasts might induce the necessity to re-optimize the trajectory during the flight. By considering a re-optimization of the trajectory during the flight they further support air traffic control towards achieving precise air traffic flow management and, in consequence, an increase in airspace and airport capacity. However, the re-optimization leads to an increase in the operator and controller’s task loads which must be balanced with the benefit of the re-optimization. From this follows that operators need a decision support under which circumstances and how often a trajectory re-optimization should be carried out. Local numerical weather service providers issue hourly weather forecasts for the coming hour. Such weather data sets covering three months were used to re-optimize a daily A320 flight from Seattle to New York every hour and to calculate the effects of this re-optimization on fuel consumption and deviation from the filed path. Therefore, a simulation-based trajectory optimization tool was used. Fuel savings between 0.5% and 7% per flight were achieved despite minor differences in wind speed between two consecutive weather forecasts in the order of 0.5 m s−1. The calculated lateral deviations from the filed path within 1 nautical mile were always very small. Thus, the method could be easily implemented in current flight operations. The developed performance indicators could help operators to evaluate the re-optimization and to initiate its activation as a new flight plan accordingly.

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