Air Temperature Fluctuations Research Articles

Empirical investigation to explore potential gains from the amalgamation of phase changing materials (PCMs) and wood shavings

• Panels containing PCM, Wood-shaving and PCM/wood-shavings amalgams are created. • Panels are subjected to heat profiles and their thermal performances were compared. • Heat peak reduction, heat peak shift and fluctuation of temperatures are examined. • Amalgamation of wood-shavings did not improve the PCM's thermal performance. • The overall weight of the panels was reduced due to amalgamating wood-shavings. The reduction of gained heat, heat peak shifting, and the mitigation of air temperature fluctuations are some desirable properties that are sought after in any thermal insulation system. It cannot be overstated that these factors, in addition to others, govern the performance of such systems thus their effect on indoor ambient conditions. The effect of such systems extends also to Heating, Ventilation and Air-conditioning (HVAC) systems that are set up to operate optimally in certain conditions. Where literature shows that PCMs and natural materials such as wood-shavings can provide efficient passive insulation for buildings, it is evident that such approaches utilise methods that are of a degree of intricacy which require specialist knowledge and complex techniques, such as micro-encapsulation for instance. With technical and economic aspects in mind, an amalgam of PCM and wood-shavings has been created to be utilised as a feasible thermal insulation. The amalgamation was performed in the simplest of methods, through submerging the wood shavings in PCM. An experimental procedure was devised to test the thermal performance of the amalgam and compare this to the performance of the same un-amalgamated materials. Comparative analysis revealed that no significant thermal gains would be expected from such amalgamation. However, a significant reduction in the total weight of the insulation system would be achieved that, in this case, shown to be up to 20.94%. Thus, further reducing possible strains on structural elements due to the application of insulation on buildings. This can be especially beneficial in vernacular architectural approaches where considerably large amounts and thicknesses of insulations are used. In addition, cost reduction could be attained as wood shavings are significantly cheaper compared to the cost of PCMs.

Совершенствование методов расчета трансформации внутрисуточного стока паводка

The purpose of the study is to develop a method for calculating flow schedules in the dams ‘ spillway structures, to consider the regularities of the flood flow transformation as a result of exceeding the inflow over the discharge of water into the pond. Given this process in the design of ponds, it is possible to reduce the maximum consumption and, accordingly, reduce the size of the spillway structures and their cost. The object of the study are ponds with small catchment areas, which are characterized by intra-day fluctuations in water flow due to intra-day fluctuations in air temperature and different rates of snow melting during the day. Most of the ponds in the Bryansk region are built on gullies, ravines, streams, very small rivers with small catchment areas, for which it is especially important to improve the methods of calculating the transformation of intraday flood flow and forecasting the shape of hydrographs, the search for the least time-consuming and the most acceptable methods of calculation. The proposed mathematical model allows to optimize the calculations.

Response of oil flax varieties to abiotic conditions of the Middle Cis-Ural region by formation of seed yield

Studying the reaction to the abiotic conditions of the Middle Urals in 16 varieties of oil flax will allow to adapt the culture: increase its productivity and product quality. As a standard, the variety ‘VNIIMK 620’ was sown. The experiments were laid on sod-podzolic medium loamy soil in the grain-grass rotation after winter crops during 2012-2015. During the years of research, the plow layer of the experimental plots had different humus contents - medium and high, mobile phosphorus and exchange potassium - medium and very high, exchange soil acidity - slightly acidic and close to neutral. To a greater extent, by 91.5%, the change in the seed yield of the studied oil flax varieties depended on the abiotic conditions of the growing season; the share of the influence of the genotype of the variety in the formation of seed yield was 3.0%. Meteorological conditions during the years of the experiments were characterized by large fluctuations in the average daily air temperature and the amount of precipitation that fell over the months, in consequence of this the seed yield of flax oil varied in wide range over both varieties and years of study. The most favorable abiotic conditions for the formation of oil flax seeds were formed in 2014, when, during the ripening period of the seeds optimal meteorological conditions have developed with hydro thermic factor of 1.0. This contributed to obtaining the highest seed yield in 2014 - 218 g/m2. On average, over four years of research, the same response to abiotic conditions with seed yield was formed in ‘VNIIMK 620’ varieties from Russia, ‘Clark’ varieties from Holland and ‘Barbara’ from Hungary. The most plastic grade is ‘Clark’ with a plasticity coefficient bi = 1.33. The most stable seed yield is the ‘Norlin’ variety with a stability coefficient of 32.2. Russian varieties ‘LM-96’, ‘N 3829’ and foreign varieties ‘Norlin’, ‘Atalante’ proved to be the most adaptable to cultivation conditions in the agroecological conditions of the Cis-Ural region and can be considered promising in terms used as starting material in the breeding process.

A phase change material selection using the interval-valued target-based BWM-CoCoMULTIMOORA approach: A case-study on interior building applications

The move towards sustainable development and energy efficient solutions in the built environment has led to develop innovative solutions, particularly in the area of indoor environmental comfort in buildings. Phase change materials (PCMs) are a potential approach to target building energy use reduction. PCMs are smart materials that have been commercialized and used in buildings for effective regulation of surface and indoor air temperature fluctuations and peak energy reductions. Appropriate PCM selection is the critical step in PCM system design that determines the full effectiveness and applicability of PCM integrated building applications. Optimal selection of PCMs can be effectively executed with the support of multiple attribute decision making (MADM) approaches. Although, the traditional MADM methods have usually focused on beneficial and non-beneficial attributes, in real-world and practical problems, decision-makers tend to determine the rank of an optimal alternative based on the target values of their attributes. In response to the knowledge gap of an existing practical and functional PCM selection solution, this study proposed a hybrid and novel target-based MADM approach that combines the best-worst method (BWM) with COmbined COmpromise SOlution (CoCoSo) and multi-objective optimization of ratio analysis plus the full multiplicative form (MULTIMOORA) with an interval-valued structure called the IV-T-BWM-CoCoMULTIMOORA approach. A case study is examined to select the optimal PCM for interior building surface applications based on a case-specific construction project in Toronto, Canada. Two separate scenarios are considered, one based on thermophysical specifications and one based on managerial preferences. The connection between both technical and managerial criteria was demonstrated to clearly affect the decision-making process to take into account both thermophysical properties of PCM alternatives in the context of risk factors and design considerations. Nevertheless, the influence of the technical parameters was shown to be dominant in the final selection of the best case scenario.

Experimental and thermal performance investigations on sensible storage based solar air heater

Abstract The thermal performance of the solar collector for air heating purpose is investigated with and without packed bed through experimental and theoretical methods. A simple flat plate solar air heater was developed with 2m2 corrugated absorber plate and integrated with porous pebble bed in the airflow path to act as a sensible heat storage medium. The experimental studies were carried out for different mass flow rates of air from 0.014 to 0.087 kg/s with the increment of 0.0095 kg/s. Steady-state theoretical models have been established to predict the thermal performance of the air heaters and the results indicated that they are well enough to predict the outlet air temperature with acceptable error percentage. The collector with packed bed storage medium is more efficient than without packed bed in terms of energy efficiency as well as in reducing temperature fluctuation of air at the outlet of the collector. The energy and exergy efficiency of the collector with packed bed veried from 20.35% to 50.92% and +3.97% to −2.807% for the airflow rates 0.014 kg/s to 0.087 kg/s respectively. Solar collectors with packed bed are capable to deliver the hot air in the range of 45 to 60 °C for a longer period and which can be preferred for achieving a better quality of the dried products as well as for space heating applications.

Novel design measures for optimizing the yearlong performance of a concentrating solar thermal power plant using thermal storage and a dry-cooled supercritical CO2 power block

Owing to water deficit and environmental concerns, the compatibility of dry cooling technology with supercritical CO2 (sCO2) power cycle in concentrated solar power (CSP) offers superior performance even at extreme climate temperatures. The CSP plant performance is expressively dominant by the erratic attributes of solar insolation and varying ambient temperature. In the present work, the dynamic attributes of the dry cooled sCO2 recompression cycle coupled with the central receiver is presented in terms of net power generation at different climate conditions. The supplementary bypass arrangement prior to the dry cooling tower ensures the system operating at the design point compressor inlet temperature in the occasion of low ambient temperatures. Solar tower plant with molten salt thermal energy storage is used to supply dispatchable electricity during nighttime. Based on the annual climate temperature profile, two sets of ambient air temperatures are selected for the cooling system design. This requires the rectification of two sets of design point main compressor inlet temperature/tower exit temperature at optimum turbine exhaust pressure in advance of the integration and design of the dry cooling tower. The key parameters of the solar system (cold tank temperature and molten salt split ratio) and power block (MCIT, pressure ratio, cycle mass, and bypass fraction) are optimized to maximize the power generation at any circumstances. The required height of the tower is 59 m and 67 m at two design points. The average net power using the minimum climate temperature is 23.71 MW and 24.09 MW respectively, whereas using the maximum climate temperature the values are 23.06 MW and 23.45 MW. The dynamic response from the system when the thermal energy storage operates during nighttime using additional bypass is demonstrated under the fluctuation of air temperature. The year-round plant performance as well as the dynamic response from the cooling tower of both cases are assessed with the historical air temperature data.

Changes in the Water Temperature of Rivers Impacted by the Urban Heat Island: Case Study of Suceava City

Cities alter the thermal regime of urban rivers in very variable ways which are not yet deciphered for the territory of Romania. The urban heat island of Suceava city was measured in 2019 and its impact on Suceava River was assessed using hourly and daily values from a network of 12 water and air monitoring stations. In 2019, Suceava River water temperature was 11.54 °C upstream of Suceava city (Mihoveni) and 11.97 °C downstream (Tişăuţi)—a 3.7% increase in the water temperature downstream. After the stream water passes through the city, the diurnal thermal profile of Suceava River water temperature shows steeper slopes and earlier moments of the maximum and minimum temperatures than upstream because of the urban heat island. In an average day, an increase of water temperature with a maximum of 0.99 °C occurred downstream, partly explained by the 2.46 °C corresponding difference between the urban floodplain and the surrounding area. The stream water diurnal cycle has been shifted towards a variation specific to that of the local air temperature. The heat exchange between Suceava River and Suceava city is bidirectional. The stream water diurnal thermal cycle is statistically more significant downstream due to the heat transfer from the city into the river. This transfer occurs partly through urban tributaries which are 1.94 °C warmer than Suceava River upstream of Suceava city. The wavelet coherence analyses and ANCOVA (analysis of covariance) prove that there are significant (0.95 confidence level) causal relationships between the changes in Suceava River water temperature downstream and the fluctuations of the urban air temperature. The complex bidirectional heat transfer and the changes in the diurnal thermal profiles are important to be analysed in other urban systems in order to decipher in more detail the observed causal relationships.

Effects of Day Length and Air Temperature Fluctuation on the Occurrence of Leaf Browning in Sesame Seedlings Cultured in a Plant Factory under Artificial Light

Effects of Day Length and Air Temperature Fluctuation on the Occurrence of Leaf Browning in Sesame Seedlings Cultured in a Plant Factory under Artificial Light

Seasonal and meteorological associations of vitamin K-dependent coagulation factors in 1-month-old infants: assessment of Normotest values

: We aimed to determine the presence of seasonal and meteorological associations of the activity of vitamin K-dependent coagulation factors to explain the seasonal variation in vitamin K deficiency-related bleeding. Seasonal and monthly changes in Normotest values in 1759 healthy 1-month-old infants were retrospectively accessed, and the impact of meteorological parameters on Normotest values was analyzed. Normotest values peaked in winter and were the lowest in summer, with statistically significant differences among the seasonal values (P < 0.001). Comparing monthly variations, the values peaked in January and were the lowest in August (P < 0.001). Only the average daily air temperature significantly correlated with the Normotest values on multiple linear regression (P < 0.001) and with low Normotest values on multiple logistic regression analysis (odds ratio, 1.023; P = 0.002). Seasonal and monthly variations in Normotest values were observed in 1-month-old infants, possibly due to fluctuations in daily air temperature.

Current trends in Green Urbanism and peculiarities of multifunctional complexes, hotels and offices greening

The analysis of domestic and world publications on the evolution of ornamental garden plants use from the ancient Egyptians, Greeks and ancient Romans to the “dark times” of the middle Ages and the subsequent Renaissance was carried out. It was made in order to understand the current trends of Green Urbanism and in particular regarding the diversity of floral and ornamental arrangements used in the design of modern interiors of public spaces. The aim of the article is to grasp current trends of Green Urbanism regarding the diversity of floral and ornamental arrangements used in the design of modern interiors of public premises. Cross-cultural comparative methods have been used, partially using the hermeneutics of old-printed texts in accordance with the modern system of scientific knowledge. The historical antecedents of ornamental gardening, horticulture, forestry and vegetable growing, new trends in the ornamental plants cultivation, modern aspects of Green Urbanism are discussed. The need for the introduction of indoor plants in the residential and office premises interiors is argued in order to create a favorable atmosphere for work and leisure. The extreme importance of selecting an assortment and developing environmentally friendly ways to increase the resistance of indoor plants against pathogens and pests in conditions of insufficient lighting, humidity, abnormal fluctuations in air temperature, etc. has been revealed. In conclusion, the world experience in the use of ornamental garden plants testifies to the eternal desire of man for unity with nature, which is especially growing in conditions of progressive urbanization. The current global trends of Green Urbanism are of particular importance in Ukraine in terms of the Ukrainian public aspirations to integrate the state into the European community.

Hydraulic conductivity changes in compacted clayey barriers due to temperature variations in landfill top covers

In landfills, due to their low hydraulic conductivity, compacted clays (CC) are commonly used in multilayered structures as base liners and cover systems. Nevertheless, the hydraulic performances of the CC layer can be affected by temperature alterations. The CC barrier of cover systems is exposed to heating caused by waste degradation processes as well as by the air temperature fluctuations, including freezing and thawing and high temperatures. Exposition occurs especially during transitory configurations when the final cap is not completed with the protective soil layers. In the present work, four clayey soils of varying plasticity all suitable for landfill barriers according to the international standard requirements are tested with respect to their sensitivity to thermal stresses in terms of hydraulic conductivity changes. For each material, experimental tests are performed on compacted specimens comparing the values obtained soon after compaction with the ones obtained after exposition to freezing–thawing or drying processes, the latter caused by heating up to 60 °C. The results show that freezing–thawing is more detrimental than heating, since the first can increase the hydraulic conductivity by up to about 20 times, while the second by less than 10 times. The soils of medium plasticity are the most affected, while the ones with high plasticity show the ability to partially withstand the effects of the investigated thermal alterations. This behavior seems related to the water absorption capacity of the material. The results suggest that the optimum water content acquired from the Proctor Standard curve seems to be a suitable indicator of this partial recovery potential.

Thermal biology of two tropical lizards from the Ecuadorian Andes and their vulnerability to climate change.

This study aims to analyze the thermal biology and climatic vulnerability of two closely related lizard species (Stenocercus festae and S. guentheri) inhabiting the Ecuadorian Andes at high altitudes. Four physiological parameters-body temperature (Tb), preferred temperature (Tpref), critical thermal maximum (CTmax), and critical thermal minimum (CTmin)-were evaluated to analyze the variation of thermophysiological traits among these populations that inhabit different environmental and altitudinal conditions. We also evaluate the availability of operative temperatures, warming tolerance, and thermal safety margin of each population to estimate their possible risks in the face of future raising temperatures. Similar to previous studies, our results suggest that some physiological traits (CTmax and Tb) are influenced by environmental heterogeneity, which brings changes on the thermoregulatory behavior. Other parameters (Tpref and CTmin), may be also influenced by phylogenetic constraints. Moreover, the fluctuating air temperature (Tair) as well as the operative temperatures (Te) showed that these lizards exploit a variety of thermal microenvironments, which may facilitate behavioral thermoregulation. Warming tolerance and thermal safety margin analyses suggest that both species find thermal refugia and remain active without reducing their performance or undergoing thermal stress within their habitats. We suggest that studies on the thermal biology of tropical Andean lizards living at high altitudes are extremely important as these environments exhibit a unique diversity of microclimates, which consequently result on particular thermophysiological adaptations.

Effect of hygrothermal behaviour of earth brick on indoor environment in a desert climate

This study describes the experimental testing of the hygrothermal properties of the earth brick and the numerical analysis of the hygrothermal behaviour of a residential building in a desert climate in order to evaluate the effect of the earth brick on the indoor environment. The hygrothermal properties, i.e. thermal conductivity, specific heat capacity, equilibrium moisture content and water vapour permeability, were characterized to be used in the following numerical simulation of indoor environment. The numerical analysis was conducted by whole building simulations using EnergyPlus which can be used to simulate the indoor climate in buildings. An existing residential building was monitored for two days in summer in order to validate the accuracy of the model. The simulated results showed that compared with the fired brick, the earth walls reduce the amplitude of both indoor air temperature and relative humidity fluctuations, especially the maximum of relative humidity, due to both thermal inertia and moisture capacity of the earth bricks. Besides, the heating energy consumption results of the earth brick rooms were significantly lower than the fired brick rooms during the heating period.

Model-based evaluation of ammonia removal in biological air scrubbers

A mechanistic model for ammonia removal in a countercurrent biological air scrubber was set up. This model was used to study the effect of the influent characteristics – air temperature, ventilation rate and ammonia load, on ammonia removal efficiency. Besides mass balances of the components participating in the biological conversions, the water mass balance and the heat balance were considered. The effects of the pH and the concentration of the nitrogen components on the driving force for mass transfer were examined. The model output was compared against experimental data from a pig housing facility. Simulations were performed to assess the usefulness of pH control and to investigate the effect of inflow air conditions on the ammonia removal efficiency. The study found out that although pH control affected the nitrogen component distribution in the washing water, it hardly affected the ammonia removal efficiency. Thus, pH control for biological air scrubbers is not recommended in practice, however, an on/off pH control system adding only acid at critical moments (pH above 7.5) could be considered. The variations in the ammonia removal efficiency are mainly caused by a changing ventilation rate rather than air temperature fluctuations or ammonia load.

Nut crops collection of "Ustymivskyi" dentrological park

Aim. The aim of the work is to characterize the diversity of nut crops in terms of the efficiency of introduction in the conditions of the southern forest-steppe of Ukraine. Results and Discussion. In the collection of tree and shrub species of the State Dendrological Park "Ustymivskyi" numbering 472 species, nut crops are represented by more than 120 species. These include fruit species of temperate and subtropical zones from different botanical families. The climate in the area of the park is moderately continental with unstable humidity, frequent snowless winters with sharp fluctuations in air temperature. Dry winds are 2-3 times a year. The amount of precipitation is 254-777 mm per year. In the spring-summer period, there are periods without rain (up to two to three months). As a result of the study, the species and forms promising for introduction in such conditions have been identified. These are representatives of the genus Juglans: J. mandshurica Maxim. (Manchurian walnut), J. cinerea L. (gray walnut), J. nigra L. (black walnut) and J. regia L. (walnut). Corylus colurna (bear hazelnut) showed exceptionally good growth and abundant fruiting. However, in the last 10 years, the trees have become dry top and dry. Shrub species C. avellana (its forms 'Purpurea', 'Laciniata') and C. pontica C. Koch. turned out to be more adapted to climate change. The endemic steppe species Amygdalus nana L. (steppe almond) can be recommended in crosses when breeding for winter hardiness and an increased content of the alkaloid amygdalin (up to 4.5%). A. triloba Ricker. (almond three-bladed, regular and terry forms) is used as a decorative type. However, due to excessive disease damage (cercosporosis, orange spot, curly leaves, burns), plants lose their decorative effect. Repeated attempts to introduce into the collection such species as Carya alba (L.) C. Koch. (pignut hickory), Pterocarya pterocarpa (Michx.) Kunth ex Iljinsk. (caucasian wingnut), Fagus sylvatica L. (common beech) and Castanea sativa Mill. (sowing chestnut) were unsuccessful: the plants quickly died. Success has been achieved in the introduction and distribution of Xanthoceras sorbifolium and Ginkgo biloba in the forest-steppe and steppe zones. Conclusions. It is recommended to introduce walnut crops isolated as a result of the study into the range of plants used in landscaping, to create perennial plantations on lands unsuitable for agricultural production.

Nematode trophic structure in the phytotelma of Neoregelia cruenta (Bromeliaceae) in relation to microenvironmental and climate variables.

The term phytotelma (pl. phytotelmata) designates a plant-associated reservoir of fresh water and organic debris. Phytotelmata in tank bromeliads are abundant in tropical forests, and they provide shelter, food, and water for many metazoans. Among the invertebrates known to inhabit phytotelmata, nematodes are the least studied, despite their important role in nutrient and energy cycles in freshwater ecosystems. This study was conceived to characterize the nematode trophic structure in the phytotelma of the bromeliad N. cruenta, and to identify climate and microenvironmental variables that impact it. Nematode abundance (total and per trophic group), rainfall, air temperature, the amount of organic debris fallen into the phytotelma, and eight physico-chemical properties (PCPs) of the water retained in the bromeliad tank – volume; temperature; pH; dissolved organic carbon, nitrogen, oxygen, and solids; and electrical conductivity – were monitored during two years in a natural reserve in Brazil. Bacterial and hyphal feeder nematodes predominated over other trophic groups. Nematode abundance (total and per trophic group) was not impacted by fluctuations in rainfall or air temperature. The amount of organic debris fallen into the phytotelma correlated positively with nematode abundance (total and per trophic group). Regarding the PCPs of water, the only significant correlation – positive – was between the amount of dissolved oxygen and the abundance of hyphal feeder nematodes. These results bring a clearer understanding of the ecology of nematodes inhabiting phytotelmata, which are peculiar and understudied freshwater ecosystems.

World’s largest chiton (Cryptochiton stelleri) is an inefficient thermoregulator

Rocky intertidal zones are some of the most thermally stressful environments on earth, where ectotherms deal with tidally driven fluctuations in air and water temperatures that can exceed their maximum thermal tolerance. However, not all intertidal ectotherms face the same exposure risk. In northern regions of the eastern Pacific, summertime low tides occur during midday, exposing ectotherms to potentially stressful temperatures, whereas cooler pre-dawn low tides in southern regions buffer ectotherms from thermal stress. Gumboot chitonsCryptochiton stelleriare thermally sensitive intertidal grazers that range from southern California to Alaska, exposing them to a mosaic of thermal stresses. We quantified chiton thermal performance limits in the laboratory by testing the effects of elevated air and water temperatures on grazing. We also compared the thermoregulation efficiency of chitons from thermally benign northern California sites with those from thermally stressful San Juan Island, Washington sites, using 3 components: (1) biomimetic thermal models deployed intertidally, (2) chiton body temperatures in the field, and (3) chiton thermal preference in a laboratory-based thermal gradient. We found that chiton grazing performance was greatly reduced at 18°C in water, and they reached their grazing performance limit after exposure to 20°C in air, confirming previous work documenting thermal limits on chiton respiration. Chitons preferred body temperatures within 3°C of their thermal performance limits, but they rarely achieved body temperatures that would maximize grazing in the field. This suggests that chitons are not thermoregulating efficiently with respect to maximizing grazing performance, but instead are minimizing exposure to temperatures that would be detrimental to their performance.

Investigation of Termomodernized Building's Microclimate with Renewable Energy

The values of indoor air temperatures in separate premises of the educational building of National University of Life and Environmental Sciences of Ukraine before and after the works on the thermo-modernization of the building were determined. A significant reduction in energy expenditure was achieved through the use of solar panels and solar collectors when changing the energy control algorithm and equipment for implementing this algorithm. The coldest rooms and premises with excess temperature are detected. The causes of uneven distribution of temperatures were analyzed. The possibility of equalizing the distribution of internal air temperatures and reducing the dependence of their values on fluctuations of external air temperatures is shown. With the help of the engineering methodology of calculation, energy efficiency of the so-called intermittent heating mode is demonstrated on the example of an educational room. It is shown that the use of the intermittent heating method can reduce energy consumption for heating. To further reduce energy costs, it is proposed to use a heat pump to compensate for peak loads and work at night at a special rate.

Hydrological impacts of interannual variations in surface soil freezing processes in the upper Nu–Salween River basin

ABSTRACT The upper Nu–Salween River basin in the Tibetan Plateau is mainly covered with seasonal frozen soils. We used daily surface freeze–thaw states, detected from Special Sensor Microwave/Imager (SSM/I) daily brightness temperature data, to analyze the variations in surface freeze–thaw states and the relationship with air temperature. We also examined baseflow to explore the influences of interannual variations in the start time of soil freezing on hydrological processes. The results showed that (1) interannual air temperature fluctuations led to differences in the area and start time of surface freezing. When surface soil froze, flow was mainly dependent on existing groundwater storage. (2) The interannual variation in the surface freezing time directly affected the flow generation processes. When soil water froze and remained in the frozen layer, it was hard to generate surface flow, so flow mainly consisted of baseflow, causing the proportion of the baseflow in the total flow to gradually increase. (3) The surface freeze–thaw states obtained from the passive microwave remote sensing data may be applied to support further research on the hydrological impacts of freeze–thaw cycle variations in plateau mountain basins.

Effect of phase change material using in building thermal comfort applications through several climate conditions.

Nowadays, buildings sector contributes to climate change by consuming a considerable amount of energy to afford thermal comfort for occupants. Passive cooling techniques are a promising solution to increase the thermal inertia of building envelopes, and reduce temperature fluctuations. The phase change materials, known as PCM, can be efficiently employed to this purpose, because of their high energy storage density. Among the various existing solutions, the present study is dedicated to solid-liquid phase change materials. Temperature evolution (according to their defined temperature range) induces the chemical change of the material and its state. For building applications, the chemical transition can be accomplished from liquid to solid (solidification) and from solid to liquid (melting). In fact, this paper presents a comparative thermal analysis of several test rooms with and without phase change materials embedded in a composite wallboard in different climates. The used PCM consist in a flexible sheet of 5 mm thickness (Energain, manufactured by the company DuPont de Nemours). The main properties of such a commercial solution have been delivered by the manufacturer and from analyses. The room model was validated using laboratory instrumentations and measurements of a test room in four cities: Lyon; Reading and Casablanca. Results indicate that this phase change material board can absorb heat gains and also reduce the indoor air temperature fluctuations during daytime. The aim of the study is to show the benefits of this layer with phase change material and compare it in different climatic zones.