scholarly journals Thermal Performance Impacts of Venting EIFS Assemblies

2021 ◽  
Author(s):  
Khaled H. Khaled
Keyword(s):  
Thermal Performance ◽  
Percentage Reduction ◽  
Insulation Layer ◽  
Building Height ◽  
Wind Speeds ◽  
Maximum Reduction ◽  
The Face ◽  
Wind Velocities

One of the key improvements in EIFS is the addition of a geometrically defined drainage gap in the continuous insulation layer to allow water that has penetrated the outer EIFS lamina to drain out by gravity to the exterior. The integration of this cavity has raised questions regarding its impact on the thermal performance of wall assemblies constructed with these vented EIFS. The objective of this research is to evaluate the thermal performance impacts, as a percentage reduction in the effective RSI-Value, of a vented EIFS assembly against a face-sealed EIFS and expand the results with respect to increased building height and wind velocities. It can be concluded from the results that a vented EIFS assembly with 2-inches of EPS foam insulation and 4-inches of fiberglass cavity insulation experiences a maximum reduction of 4% in the whole assembly’s effective RSI-value against a face-sealed EIFS assembly. Furthermore, increased wind speeds, caused by installing EIFS at higher elevations from the grade had negligible effects on the thermal resistances of the face-sealed and vented EIFS

scholarly journals Thermal Performance Impacts of Venting EIFS Assemblies

2021 ◽  
Author(s):  
Khaled H. Khaled
Keyword(s):  
Thermal Performance ◽  
Percentage Reduction ◽  
Insulation Layer ◽  
Building Height ◽  
Wind Speeds ◽  
Maximum Reduction ◽  
The Face ◽  
Wind Velocities

One of the key improvements in EIFS is the addition of a geometrically defined drainage gap in the continuous insulation layer to allow water that has penetrated the outer EIFS lamina to drain out by gravity to the exterior. The integration of this cavity has raised questions regarding its impact on the thermal performance of wall assemblies constructed with these vented EIFS. The objective of this research is to evaluate the thermal performance impacts, as a percentage reduction in the effective RSI-Value, of a vented EIFS assembly against a face-sealed EIFS and expand the results with respect to increased building height and wind velocities. It can be concluded from the results that a vented EIFS assembly with 2-inches of EPS foam insulation and 4-inches of fiberglass cavity insulation experiences a maximum reduction of 4% in the whole assembly’s effective RSI-value against a face-sealed EIFS assembly. Furthermore, increased wind speeds, caused by installing EIFS at higher elevations from the grade had negligible effects on the thermal resistances of the face-sealed and vented EIFS

Geometric and Material Optimization of Vortex-Induced Vibration Micro Energy Harvesters for Localized Wind Environments

2012 ◽  
Author(s):  
Jesse J. French ◽  
Colton T. Sheets
Keyword(s):  
Energy Harvesting ◽  
Power Output ◽  
Fluid Velocity ◽  
Frequency Variation ◽  
Vortex Induced Vibration ◽  
Energy Harvesters ◽  
Wind Speeds ◽  
Material Optimization ◽  
Piezoelectric Energy ◽  
Wind Velocities

Wind energy capture in today’s environment is often focused on producing large amounts of power through massive turbines operating at high wind speeds. The device presented by the authors performs on the extreme opposite scale of these large wind turbines. Utilizing vortex induced vibration combined with developed and demonstrated piezoelectric energy harvesting techniques, the device produces power consistent with peer technologies in the rapidly growing field of micro-energy harvesting. Vortex-induced vibrations in the Karman vortex street are the catalyst for energy production of the device. To optimize power output, resonant frequency of the harvester is matched to vortex shedding frequency at a given wind speed, producing a lock-on effect that results in the greatest amplitude of oscillation. The frequency of oscillation is varied by altering the effective spring constant of the device, thereby allowing for “tuning” of the device to specific wind environments. While localized wind conditions are never able to be predicted with absolute certainty, patterns can be established through thorough data collection. Sampling of local wind conditions led to the design and testing of harvesters operating within a range of wind velocities between approximately 4 mph and 25 mph. For the extremities of this range, devices were constructed with resonant frequencies of approximately 17 and 163 Hz. Frequency variation was achieved through altering the material composition and geometry of the energy harvester. Experimentation was performed on harvesters to determine power output at optimized fluid velocity, as well as above and below. Analysis was also conducted on shedding characteristics of the device over the tested range of wind velocities. Computational modeling of the device is performed and compared to experimentally produced data.

Effects of temperature and wind on facial temperature, heart rate, and sensation

1976 ◽  
Vol 40 (2) ◽  
pp. 127-131 ◽  
Author(s):  
J. LeBlanc ◽  
B. Blais ◽  
B. Barabe ◽  
J. Cote
Keyword(s):  
Heart Rate ◽  
Skin Temperature ◽  
Subjective Evaluation ◽  
Temperature Measurements ◽  
Wind Speeds ◽  
Reflex Bradycardia ◽  
The Face ◽  
Cooling Effects ◽  
Effects Of Temperature ◽  
Cold Wind

Skin temperature measurements of the face have shown that the cheek cools faster than the nose and the nose faster than the forehead. The cooling effect of wind is maximum at wind speeds between 4.5 and 6.7 m/s. Cold winds produce significant bradycardia, which is, however, much more pronounced during the expiratory phase of respiration. A significant correlation was noted between cooling of face and the reflex bradycardia observed. Similarly, a very significant correlation was noted between drop in skin temperature and subjective evaluation of cold discomfort. Consequently, the drop in skin temperature, reflex bradycardia, and subjective evaluation are parameters which are directly affected by cold wind and can be used as adequate indicators of the degree of discomfort. When comparing the present results with the windchill index, it was found that in the zone described as “dangerously cold” the index fits well with the physiological measurements. In the zone described as “bitterly cold,” the index by comparison with actual skin temperature measurements and subjective evaluation underestimates the cooling effects of combined temperature and wind by approximately 10 degrees C.

scholarly journals Investigation of the Thermal Performance of Energy Tunnel Equipped with the Insulation Layer Considering Ventilation and Groundwater Seepage

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Guozhu Zhang ◽  
Ziming Cao ◽  
Xu Zhao ◽  
Yongli Xie ◽  
Xiaohua Liu ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Groundwater Flow ◽  
Exchange Rates ◽  
Thermal Performance ◽  
Surrounding Rock ◽  
Interface Temperature ◽  
Insulation Layer ◽  
Groundwater Seepage ◽  
Ground Heat Exchangers ◽  
Reduction Effect

The insulation layer is usually installed in the tunnel structure, whereas the influence of the insulation layer on the thermal behavior of energy tunnel ground heat exchangers (GHEs) is rarely investigated. The model tests were performed in this study to evaluate the heat transfer potential of the energy tunnel with the insulation layer under ventilation and groundwater seepage. The results can be obtained as follows: first, the fluctuations of air temperature and surrounding rock temperature at different locations are relevant to insulation layer, ventilation, and groundwater seepage. Second, the reduction effect of ventilation on the interface temperature of tunnel lining and surrounding rock is alleviated when using an insulation layer, and the interface temperature at upstream section of groundwater seepage is more easily affected by the energy tunnel GHEs. Third, the variation range of ground temperature is wider at the downstream section of groundwater flow. Moreover, the heat exchange rates of tunnel without the insulation layer improve by 5.82% and 6.45% with increasing wind speed at two groundwater flow velocities of 1 × 10 − 4 and 5 × 10 − 4  m/s, and there are only 2.03% and 0.77% enhancements of heat exchange rates by ventilation for the tunnel with the insulation layer. However, the thermal performance of the energy tunnel improved by groundwater is less relevant to the existence of the insulation layer. The relevant findings can provide an effective guidance for the following research and design of the energy tunnel.

Magnetic field generation by baroclinic waves

1975 ◽  
Vol 347 (1648) ◽  
pp. 125-140 ◽  
Keyword(s):  
Magnetic Field ◽  
Plane Layer ◽  
Rotating Magnetic Field ◽  
Magnetic Field Generation ◽  
Dynamo Action ◽  
Wind Speeds ◽  
Baroclinic Waves ◽  
The Face ◽  
Layer I ◽  
Horizontal Density Gradient

The general theory of the linear instabilities created by density differences in a rotating magnetic system is considered, and is applied to a plane layer stably stratified but with a slight superimposed horizontal density gradient that can give rise to baroclinic waves, modified by the presence of a horizontal co-rotating magnetic field parallel to the thermal wind. It is shown that, unlike the conceptually similar models of Gilman, regeneration of this magnetic field by the waves in the face of a slight resistivity of the medium can only occur within the critical layer, i. e. the diffusive layer surrounding the level at which wave and wind speeds are equal. Conditions for such self-sustaining dynamo action are given.

Comparison of Different Liquid Cooling Configurations for Effective Thermal Management of Li-Ion Pouch Cell for Automotive Applications

2020 ◽  
Author(s):  
Shashwat Bakhshi ◽  
Prahit Dubey ◽  
A. K. Srouji ◽  
Zenan Wu
Keyword(s):  
Thermal Management ◽  
Thermal Performance ◽  
Thermal Gradient ◽  
Battery Pack ◽  
Thermal Gradients ◽  
Liquid Cooling ◽  
Battery Thermal Management ◽  
The Face ◽  
Cooling Mechanism ◽  
Face Cooling

Abstract An effective cooling mechanism is the backbone of a good automotive battery thermal management system (BTMS). In addition to prevention of extreme events such as thermal runaway, an automotive BTMS must be able to efficiently tackle aggressive environmental temperatures, and/or discharge and charge conditions during electric vehicle operation. Moreover, electrical performance and cycle life of the battery modules and packs are closely tied to the battery temperatures and thermal gradients, which increase with increase in C-Rates. In order to keep the battery temperatures to be under the operational temperature limit, it is crucial that the selected cooling mechanism provides efficient transport of the heat generated by the battery modules and packs to the cooling media under all discharge and charge conditions. Owing to its efficient thermal performance, liquid cooling is preferred by most electric vehicle manufacturers for battery thermal management. This usually incorporates battery modules exchanging heat with a flowing coolant via cold plate or cooling channels during operation. The current work aims to investigate different liquid cooling configurations and compare their relative thermal performance during operation of a high energy density Pouch Cell. The four configurations selected for this comparison are (1) Face cooling, (2) Single-Sided cooling, (3) Double-Sided cooling, and (4) a Hybrid cooling configuration. Test setups comprising of a commercially available 9 A-h NMC Pouch cell, cold plates, pump, heat exchanger, refrigeration cooling unit, and thermal sensors are built for the above four cooling configurations. During the tests, the selected cell is discharged at different discharge rates (C-Rates), i.e., 3C, 4C, and 5C. The overall cell temperatures and thermal gradient across the cell are measured using T-type thermocouples for the four cooling configurations. In order to capture the thermal gradient across the Pouch cell accurately, several thermocouples on the face of the cell are installed using a thermal interface material. Results show the superiority of Face cooling configuration in terms of overall thermal performance under all considered test conditions. Lowest cell temperatures and thermal gradients across the cell are observed for the Face cooling configuration, while highest temperatures and thermal gradients are observed for the Single-Sided cooling configuration. Much improved thermal performance is also observed in the case of the Hybrid cooling configuration as compared to the Single and Double-Sided cooling configurations. As implementation of the Face cooling configuration at the battery pack level may result in higher weight and cost of the battery pack, owing to its good thermal performance and straightforward scaling to battery pack level, the proposed hybrid liquid cooling mechanism provides a viable alternative to Face cooling for battery thermal management.

Comparative Analysis of the Use of Thermal Insulation Materials Depending on Climatic Conditions and Comfort Microclimate Supply Systems

2022 ◽  
Vol 906 ◽  
pp. 99-106
Author(s):  
Siranush Egnatosyan ◽  
David Hakobyan ◽  
Spartak Sargsyan
Keyword(s):  
Energy Efficiency ◽  
Comparative Analysis ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Climatic Conditions ◽  
Insulation Material ◽  
Insulation Layer ◽  
Transfer Resistance ◽  
Insulation Materials ◽  
Wide Range

The use of thermal insulation materials to reduce the heating and cooling demand of the building in order to provide energy efficiency is the main solution. But there is a wide range of these products on the market and, therefore, the choice and application of these materials is a rather difficult task, since many factors must be taken into account, such as environmental safety, cost, durability, climatic conditions, application technology, etc. Basically, comfort microclimate systems are designed based on normative standards, where the thickness of the thermal insulation material is selected depending on the required heat transfer resistance. These values are calculated taking into account climate conditions, that is the duration of the heating period, as well as taking into account sanitary and hygienic requirements. This article discusses the thermal performance of building materials, and also provides a comparative analysis of the use of thermal insulation materials depending on climatic factors and on the system providing comfort microclimate. Based on the calculations by mathematical modeling and optimization, it is advisable to choose the thickness of the thermal insulation, taking into account the capital and operating costs of the comfort microclimate systems. Comparing the optimization data with the normative one, the energy efficiency of the building increases by 50-70% when applying the optimal thickness of the thermal insulation layer, and when the thermal insulation layer is increased, the thermal performance of the enclosing structures has improved by 30%, which contributes to energy saving.

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