Solar Radiation Heat Research Articles

Metallic sulfide nanoparticles anchored graphene oxide: Synthesis, characterization and reduction of methylene blue to leuco methylene blue in aqueous mixtures

Oxidizing graphite (Gt) to graphene oxide (GO) through non-explosive oxidizing mixture at 55 °C is reported with high yield. GO was anchored with NiS, ZnS, and CdS metallic sulfide nanoparticles (MSNPs) in 1:1 ratio at 85 °C. MSNPs were obtained by using chloride salts of Ni, Zn, and Cd metals with thiourea in 1:3 ratio in aqueous GO for in situ doping. The GO and MSNPs doped GO (MSNP-GO) were characterized with X-ray diffraction (XRD), FTIR, UV–Vis spectrophotometry, Raman spectroscopy and thermogravimetric analysis (TGA). The GO, CdS-GO, NiS-GO, ZnS-GO had photocatalyzed methylene blue (MB) reduction by 88, 97.22, 79.68, and 89.87% to leuco MB (LMB) colorless, in aqueous medium respectively. Contrary to NiS-GO, the CdS and ZnS increased MB reduction by 9 and 1.87% respectively by weakening intersheet Vander Waals forces of GO for availing surface area. Ni2+ with 3d8 catalyzed 8.32% less MB to LMB than Zn2+ with 3d10 and Cd2+ with 4d10. MSNPs were uniformly anchored within the 2D GO sheets through sulfide anions (S2−) releasing activity for a higher reduction from water and electronically active solvents. MSNP-GO-MB-LMB ventures a novel host-guest chemistry as the MB with sp2 along with sp2-sp3 hybridizations of GO are photocatalyzed to LMB. MSNP-GO-MB-LMB formulates a multifunctional nanocluster to absorb solar radiation energy and heat contents due to MSNPs-GO interfaces. Likewise ethylene (EB) and propylene blue (PB) could be separated through selective reductions as per their hydrophobicity.

Analysis of solar radiation heat transfer of architectural fabric membrane material

In recent years, the application of membrane structures in industrial storage buildings has been widely praised due to its light weight, high transparency, self-cleaning, and other advantages. The textile membranes consist of polyester fiber substrate and polyvinyl chloride or polyvinylidene fluoride flame-retardant coatings. It occupies the main market of architectural membrane materials in China. However, the fabric membrane material has high heat transfer coefficient, poor thermal insulation, and high light transmittance performance, being affected significantly by solar radiation intensity. These thermal optical properties are lead to a poor indoor thermal environment of industrial storage buildings. This article aims to overcome the difficulties in analyzing the fabric membrane materials solar radiation heat transfer. The complexity of heat transfer is mainly caused by the hourly solar radiation and the curved roofing of fabric membrane structure industrial storage building. Therefore, a solar radiation heat transfer model was established using MATLAB program. In this article, the different directions hourly heat gained of an actual membrane structures storage building located at Wuhan in China was calculated. The calculation results of solar radiation heat gained between the grid generation method with MATLAB and the projection method were compared. This study may provide a reference for analyze the solar radiation heat transfer and design of the practical fabric membrane structures building application.

МЕЗОМАСШТАБНАЯ МЕТЕОРОЛОГИЧЕСКАЯ МОДЕЛЬ TSUNM3 ДЛЯ ИССЛЕДОВАНИЯ И ПРОГНОЗИРОВАНИЯ СОСТОЯНИЯ МЕТЕОПАРАМЕТРОВ ПРИЗЕМНОГО СЛОЯ АТМОСФЕРЫ НАД КРУПНЫМ НАСЕЛЕННЫМ ПУНКТОМ

The paper describes the mathematical formulation and numerical method of the TSUNM3 high-resolution mesoscale meteorological model being developed at Tomsk State University. The model is nonhydrostatic and includes three-dimensional nonstationary equations of hydrothermodynamics of the atmospheric boundary layer with parameterization of turbulence, moisture microphysics, long-wave and short-wave (solar) radiation, and advective and latent heat flows in the atmosphere and at the boundary of its interaction with the underlying surface. The numerical algorithm is constructed using structured grids with uniform spacing in horizontal directions and condensing to the Earth surface in the vertical direction. When approximating the differential formulation of the problem, the finite volume method with the second order approximation in the spatial variables is used. Explicit-implicit approximations in time (Adams–Bashforth and Crank–Nicolson) are used to achieve second-order accuracy in time. The paper presents results of numerical forecasting of the main meteorological parameters of the atmosphere (temperature, humidity, wind speed and direction) and precipitation in different seasons in the Siberian region. The models were tested with the help of observations obtained using the Volna-4M sodar, MTR-5 temperature profile meter, and Meteo-2 ultrasonic weather stations of the Atmosfera Collective Use Center. The improved TSUNM3 model is shown to adequately reflect the precipitation time and intensity. However, in some cases, the times of its beginning and end do not always coincide, the difference can reach several hours. The precipitation phase state is reflected reliably. Over 70% of precipitation cases are confirmed by numerical calculations. The model satisfactorily predicts temperature and humidity characteristics. The quality of the precipitation forecast model is comparable to the modern mesoscale models, such as the Weather Research and Forecasting (WRF) model.

Access to shade reduces DNA damage of Holstein cows under mild heat stress

Context The effect of heat stress on the production and physiology of lactating dairy cows is well documented in literature. However, little is known about the effect of the provision of shade on DNA damage. Aims The present study aimed to evaluate the effects of shade provision on physiological, oxidative-stress, and DNA-strand damage in dairy cows exposed to mild heat stress. Methods The study was conducted at Lages, SC, Brazil, during 15 days in a southern hemisphere summer (January and February), with 14 lactating Holstein (n = 10) and Holstein × Jersey crossbreed (n = 4) dairy cows. Animals were randomly allocated to two groups of seven animals each (named as shaded and unshaded). These two groups were evaluated in the following three different periods: pre-stress period (5-day duration), stress period (4-day duration) and post-stress period (6-day duration). Shaded cows had free access to shade throughout the study; unshaded cows were prevented from accessing shade only in the stress period. Physiological (rectal temperature, heart and respiratory frequencies and panting score) and DNA-damage parameters (through Comet assay), as well as oxidative stress (in blood: carbonyl content, nitrite:nitrate ratio, thiobarbituric acid-reactive substances, TBARS) were evaluated. Key results In the stress period, shade deprivation resulted in higher values of respiratory rate, indicating that cows were under heat stress. In addition, DNA-damage levels were higher in this circumstance, probably due to inhibition of the DNA-repair systems by the thermal stress as well as thermal stress acting as a DNA-damage agent. Conclusions In a high-altitude subtropical region, during the hot season, shade provision decreases solar radiation heating effects and, thus, reduces DNA damage and the negative effects on cow metabolism and cell structure. Implications Shade effects on cow metabolism and cell structure must be taken into consideration in the planning of dairy farms and our results suggest that shade availability must not be disregarded, even in situations of mild heat stress.

Uncertainty in Net Surface Heat Flux due to Differences in Commonly Used Albedo Products

AbstractThe ocean surface albedo is responsible for the distribution of solar (shortwave) radiant energy between the atmosphere and ocean and therefore is a key parameter in Earth’s surface energy budget. In situ ocean observations typically do not measure upward reflected solar radiation, which is necessary to compute net solar radiation into the ocean. Instead, the upward component is computed from the measured downward component using an albedo estimate. At two NOAA Ocean Climate Station buoy sites in the North Pacific, the International Satellite Cloud Climatology Project (ISCCP) monthly climatological albedo has been used, while for the NOAA Global Tropical Buoy Array a constant albedo is used. This constant albedo is also used in the Coupled Ocean–Atmosphere Response Experiment (COARE) bulk flux algorithm. This study considers the impacts of using the more recently available NASA Cloud and the Earth’s Radiant Energy System (CERES) albedo product for these ocean surface heat flux products. Differences between albedo estimates in global satellite products like these imply uncertainty in the net surface solar radiation heat flux estimates that locally exceed the target uncertainty of 1.0 W m−2 for the global mean, set by the Global Climate Observing System (GCOS) of the World Meteorological Organization (WMO). Albedo has large spatiotemporal variability on hourly, monthly, and interannual time scales. Biases in high-resolution SWnet (the difference between surface downwelling and upwelling shortwave radiation) can arise if the albedo diurnal cycle is unresolved. As a result, for periods when satellite albedo data are not available it is recommended that an hourly climatology be used when computing high-resolution net surface shortwave radiation.

The importance of cross-calibration and protecting water temperature sensors against direct solar radiation heating in hydrological studies

ABSTRACTWater temperature monitoring is important in many scientific studies. This study compares three models of water temperature sensors (Vemco Minilog II, HOBO TidbiT and HOBO Pendant) to test the importance of: (1) using cross-calibration to minimize relative errors, (2) using cross-calibration to improve on the accuracy of less accurate sensors, and (3) protecting sensors against direct solar radiation heating. The results show that when the same sensor models are cross-calibrated, the relative error can be reduced (Vemco: 0.01°C; HOBO TidbiT: 0.02°C; and HOBO Pendant: 0.07°C). Cross-calibration can also improve less accurate sensors (HOBO TidbiT and Pendant) to similar accuracies of Vemco (±0.1°C). Finally, no evidence of solar radiation heating was observed for Vemcos (unprotected); however, HOBO TidbiT and Pendant showed heating up to 2°C (maximum). When HOBO TidbiT and Pendant are shielded (flow-through system), heating is no longer an issue.

Study of cracking of methane for hydrogen production using concentrated solar energy

In this study, the cracking phenomenon of methane taking place in a cylindrical cavity of 16 cm in diameter and 40 cm in length under the heat of concentrated solar radiation without any catalyst is analysed. Three cases have been chosen; in all cases the primary phase contains methane and hydrogen gases. In the first case, we consider two phases; the secondary phase is a homogeneous carbon black powder with 50 nm of diameter; in the second case we have three phases where the two secondary phases are a particles powder with two diameters 20 and 80 nm and finally, a third case of five phases with a powder of four different diameters 20, 40, 60 and 80 nm. The low Reynolds K-ε turbulence model was applied. A calculation code "ANSYS FLUENT" is used to simulate the cracking phenomena where an Eulerian – Eulerian model is applied. The choice of several diameters greatly increases the calculation time but it approaches more of the physical reality of the radiation by these particles during the cracking. Results have shown that increasing the number of diameters gives higher cracking rates; the case of the powder of 4 different diameters gives the highest cracking rate. A parametric study as a function of the inlet velocity, carbon particle diameters and the intensity of solar radiation is realized. For the cracking heat, provided by the choice of the two concentrators of 5 and 16 MW/m2 used in this simulation, the CH4 inlet velocity is a decisive parameter for the cracking rate. Any increase in the inlet velocity requires more heat and this leads to a decrease in the cracking rate. For a velocity not exceeding 0.177 m/s (i.e. 0.3 L/min), both solar concentrations give the same amount of hydrogen produced. These quantities of hydrogen obtained reach maximum values for an inlet flow rate of CH4 between 0.58 L/min (i.e. 0.34 m/s) and 0.62 L/min (i.e. 0.3655 m/s) for both reactors. The results are interpreted and compared with experimental work.

Genetic Selection for Thermotolerance in Ruminants.

Simple SummaryRuminants make important contributions to agricultural production, protein food security, livelihoods, and socio-cultural values, particularly in the developing world. Changing climate has dire consequences on animal agriculture and presents a real challenge for humankind. Increasing temperatures, solar radiation, humidity, and resultant heat waves, low rainfall, and drought compromise the availability of forage and water. These environmental factors adversely affect animal growth and reproduction and increase disease incidence as well as threaten biodiversity. The mitigation of such effects has been confined to location or breeds and is often expensive and not always sustainable in view of continuous variations in the climatic data. In this review we have proposed that genetic selection and breeding of thermotolerant ruminants provide a sustainable means of minimizing the effect of climate change on their production. Given the variation in the ability of ruminants to tolerate heat stress and the availability of genomic tools to pursue this agenda, heat stress can be minimised. This is a shared responsibility, requiring action by stakeholders across all sectors of society.Variations in climatic variables (temperature, humidity and solar radiation) negatively impact livestock growth, reproduction, and production. Heat stress, for instance, is a source of huge financial loss to livestock production globally. There have been significant advances in physical modifications of animal environment and nutritional interventions as tools of heat stress mitigation. Unfortunately, these are short-term solutions and may be unsustainable, costly, and not applicable to all production systems. Accordingly, there is a need for innovative, practical, and sustainable approaches to overcome the challenges posed by global warming and climate change-induced heat stress. This review highlights attempts to genetically select and breed ruminants for thermotolerance and thereby sustain production in the face of changing climates. One effective way is to incorporate sustainable heat abatement strategies in ruminant production. Improved knowledge of the physiology of ruminant acclimation to harsh environments, the opportunities and tools available for selecting and breeding thermotolerant ruminants, and the matching of animals to appropriate environments should help to minimise the effect of heat stress on sustainable animal genetic resource growth, production, and reproduction to ensure protein food security.

A Comparison of the Effects of Solar Radiation on Sandy-Loam and Clay-Loam Soils with Convective Boundary Condition

A comparison of the effects of solar radiation on sandy-loam and clay-loam soils with convective boundary condition was made. The dimensional governing equations (the continuity, momentum and energy equations) were converted to non-dimensional form using some set of dimensionless quantities, which resulted to a pair of partial differential equations of second order. With the use of perturbation method, these equations were reduced to ordinary differential equation and then solved analytically. Using the numerical values of the thermal conductivities of sandy-loam and clay-loam soils, a good comparison was made between the effects of the solar radiation parameter and internal heat generation parameter on the two soil samples. These results were worked out with the use of Matlab R2009b and visibly displayed on graphs for clearer illustration. For a rise in the intensity of solar radiation and mounting internal heat, the temperature of the soils increased generally. However, the proportion of moisture content influenced the level and the rate at which the temperature is boosted in both soil samples.

A numerical study on induced flowrate and thermal efficiency of a solar chimney with horizontal absorber surface for ventilation of buildings

Solar chimneys absorb solar radiation heat to create stack effect which induces airflow for natural ventilation of buildings. Solar chimneys have been studied mainly in two forms: vertical air channel and inclined one. In this paper, a solar chimney with a horizontal absorber surface was proposed. Its performance in term of the induced air flowrate through the channel and the thermal efficiency was predicted by a CFD (Computational Fluid Dynamic) model. Examined factors included the heat flux and major dimensions of the chimney: length of the absorber surface, gap of the air channel, and height and width of the inlet and outlet sections. The results show that increasing of all examined factors enhances the flowrate but has minor effect on the thermal efficiency. However, excessive large outlet width results in reduction of the flowrate and thermal efficiency due to appearance of reverse flow at the outlet.

The Nearshore Heat Budget: Effects of Stratification and Surfzone Dynamics

AbstractTemperature variability in the nearshore (from ≈6‐m depth to the shoreline) is influenced by many processes including wave breaking and internal waves. A nearshore heat budget resolving these processes has not been considered. A 7‐month experiment at the Scripps Institution of Oceanography Pier (shoreline to 6‐m depth) measured temperature and surface and cross‐shore heat fluxes to examine a nearshore heat budget with fine cross‐shore spatial (≈20 m) and temporal (5 day to 4 h) resolution. Winds, waves, air and water temperature, and in particular, pier end stratification varied considerably from late Fall to late Spring. The largest heat flux terms were shortwave solar radiation and baroclinic advective heat flux both varying on tidal time scales. The net heat flux is coherent and in phase with the nearshore heat content change at diurnal and semidiurnal frequencies. The binned mean heat budget has squared correlation R2=0.97 and best‐fit slope of 0.76. Including an elevated breaking wave albedo parameterization reduced the residual heat flux and improved the best‐fit slope. Baroclinic and barotropic advective heat fluxes have significant noise, and removing them from the heat budget improves the best‐fit slope when stratification is weak. However, when daily mean stratification is large, baroclinic advective heat flux dominates variability and is required to capture large (≈3 °C h−1) internal wave events. At times, large heat budget residuals highlight neglected heat budget terms, pointing to surfzone alongshore advection of temperature anomalies.

Influence of Solar Radiation Heat Input into Room on Level of Economically-efficient Thermal Protection of Building

Techniques for choosing an energy and economically feasible thermal protection of buildings in the climatic conditions of Moscow are discussed earlier. An important basis of these techniques is that it was possible to identify the thermal parameters on the basis of which the generalization of the basic energy and economic indicators of the building, depending on its thermal protection, was carried out. The methods were tested for buildings whose working day lasts from 9 am to 6 pm with various internal heat generation. In this case, it was believed that solar radiation is completely obscured. From consideration of the effect of heat gains on energy-efficient thermal protection, it was found that with increasing heat gains, the load on heating systems decreases regardless of the level of heat protection, and the load on the room cooling systems increases more with higher thermal protection than with low thermal protection. However, there are buildings of a number of functional purposes in which solar radiation is partially obscured or not obscured at all. These include some commercial, residential and other buildings. Accounting for heat gains from solar radiation, with variable intensity throughout the year, makes significant adjustments to the choice of the level of thermal protection. This is due to the fact that often cooling of the room is required during periods when the outside air temperature is below the maximum allowable temperature of the room. During these periods, enhanced thermal protection is an obstacle to the natural outflow of heat from the premises. Calculations showed that the higher the heat gain from solar radiation, the smaller the proportion of buildings it is energetically feasible to warm according to the basic standards stipulated in SP 50.13330.2012. And although it is not energetically feasible to carry out thermal insulation for sanitary and hygienic requirements, the conclusions about the benefits of building insulation with reduced heat transfer to the walls and coatings of a building are economically significant. It is also important that when identifying an economically feasible thermal protection of a building, it is necessary to take into account all the components of financial expenses that are affected by the thermal protection of a building. The calculations also showed that an increase in the cost of heat and electricity over time changes the thermal performance of buildings for which this or that thermal protection is economically feasible.

The design of STEM Education lessons on statistical mechanics for undergraduate students

Lessons combining of the integration of Science, Technology, Engineering and Mathematics or STEM Education were designed and used to enhance learning activities in a Statistical Mechanics classroom for undergraduate students at Ubon Ratchathani University, Thailand. Three STEM Education activities were introduced into the classroom including, solar drying project, magnetic induction, and heat radiation. The STEM Education activities will be described in details. The students were introduced to STEM Education and problem-based project learning. The students were trained to solve real problems by concentrating on engineering problems and then thoughtfully guided by instructor’s questions to apply all subject matter of Statistical Mechanics (Science) and techniques and student’s skills of Technology, Engineering and Mathematics. The students were able to gain and build up their own knowledge and skills necessary for 21st century. The students were impressed by the STEM Education activities. The students’ satisfactory toward the STEM Education activities was in the highest level.

Fabrication of New Thermoelectric Block Floor for Power generator

This was the study and designing of the thermoelectric block floor for power generator that are normally used for footpaths, traffic islands, and gardening together with solar radiation heat. Physically, this thermoelectric block is an octagonal block with a size of 19.8 × 19.8 × 6 cm. The block was composed of two layers. The upper layer received the solar radiation and produced the thermoelectric module heat by synthesizing thermoelectric materials and creating 4 thermoelectric modules from Bi2Te3 for one composition set where an aluminum sheet was used for cooling. Additionally, the lower layer was exposed to the ground with low temperature to produce the usable electric power. The efficiency of this electric power was tested with the solar radiation heat of the thermoelectric block floor and by the Thai Industrial Standards (TIS) 827-2531: Interlocking Concrete Paving Blocks. After installing the thermoelectric block floor at the Faculty of Industrial Technology, Sakon Nakhon Rajabhat University, it was found that the block was usable as defined by TIS 827-2531: Interlocking Concrete Paving Blocks; meanwhile, the test on the electric power of the thermoelectric block floor indicated that the maximum electric potential difference was 73.91 mV where the temperature difference was 6.2 K measured from the surface of the block. In addition, the maximum electric power was 88.25 mV where the solar radiation was 1124.5 W m-2. Notably, this electric power of the thermoelectric block floor was directly variable following the solar radiation value. However, if used for power generator or as an alternative energy for engineering activities, the thermoelectric block should be properly designed and developed to produce higher level of electric power and more of them should be created for both series circuit and parallel circuit.

Experimental study of the thermal protection performance of the high reflectivity-phase change material (PCM) roof in summer

In order to reduce the building heat gain through the roof, a new kind of high reflectivity-PCM roof was proposed. That is to lay a layer of PCM outside the common roof, then a layer of high reflectivity film was laid outside the PCM layer. To compare the thermal protection performance of the high reflectivity-PCM roof with PCM roof, high reflectivity roof and common roof, three real size rooms were built. The three rooms were first installed with PCM roof, reflectivity roof and common roof. The thermal protection performance of the three roofs was compared for eight days (July 23rd to July 30th). Then the PCM roof and the high reflectivity roof were combined to form the high reflectivity-PCM roof, and the thermal protection performance of the high reflectivity-PCM roof was also compared to that of common roof for another eight days (Aug. 17th to Aug. 24th). Results showed that the high reflectivity-PCM roof performed more excellent in decreasing indoor air temperature, inner surface temperature and inner surface heat flux. Thermal balance results showed that the new type of roof can significantly reduce the solar radiation heat gain and storage most part of the heat passing through the high reflectivity film. The high reflectivity-PCM roof had better thermal protection performance than the other three roofs.

Ensemble-Averaging Resolves Rapid Atmospheric Response to the 2017 Total Solar Eclipse

Rapid changes in solar radiative forcing influence heat, scalar and momentum fluxes and thereby shift the trajectory of near-surface atmospheric transitions. Surface fluxes are difficult to obtain during atmospheric transitions by either bulk or eddy-covariance methods because both techniques assume quasi-stationarity in atmospheric state and require sufficiently long blocks of data, typically on the order of 10-30 min, to obtain statistically significant results. These computational requirements limit the temporal resolution of atmospheric processes that researchers can examine using traditional measurement techniques. In this paper, we present a novel observational approach to calculate surface fluxes at sub-minute temporal resolution. High-frequency data from a horizontal, log-spaced array of nine time-synchronized ultrasonic anemometers were used to perform spatial-temporal ensemble averaging and obtain eddy-covariance turbulence fluxes at unprecedented time resolution. The 2017 Great American Solar Eclipse event provided a ‘natural experiment’ to test the ensemble-observation and averaging approach. A total eclipse is energetically well-constrained and, unlike day/night transitions, is a perturbation that quickly transitions from and back to a state of significant solar forcing, providing an ideal scenario for testing the space-timescales required for surface flux calculations. Additionally, two Doppler lidars and a vertically-oriented Distributed Temperature Sensing (DTS) system provided measurements to characterize near-surface atmospheric conditions. Results show that the ensemble-averaged sensible heat fluxes converged at timescales as short as 15 s. Additional analyses show that the timescale of the connection between the surface and the atmosphere is more rapid than previous measurements have been capable of showing, and is on the order of 10 minutes or less. This experiment demonstrates that ensemble-flux measurements are capable of resolving fluctuations in surface fluxes during rapid atmospheric transitions.

A study of the physico-chemical properties of dried maritime pine resin to better understand the exudation process

Abstract The aim of this study was to have a better understanding of the phenomenon of resin exudation on pinewood boards due to the liquefaction of the resin caused by the heat of solar radiation. Resin exudation is a crucial problem for the maritime pine industry, as it may strongly decrease the wood’s aesthetics submitted to outdoor exposure. The softening temperature of dried pine resin was analyzed and the results were examined relative to its physico-chemical properties. To achieve this, resin samples were dried under different conditions (60°C, 120°C during 16 h and at 150°C during 24 h). After 3 months of post-drying at ambient temperature, their softening temperatures were measured by thermomechanical analysis. These same samples were subsequently studied to determine their chemical, structural and morphological properties. Samples with a low drying temperature (60°C) had high opacity attributed to crystallinity and porosity. These elements partially explained a higher softening temperature than for the other samples. Different chemical modifications of resin were also observed due to temperature, with a significant amount of oxidized derivatives for samples dried at low temperature and dehydrogenated compounds for samples dried at high temperature.

Analysis on the influence of solar radiation on heating load of existing residential buildings in Western Sichuan

The calculation of the solar radiation heat is important to the accuracy of heating load prediction, especially in area with sufficient solar radiation, e.g. western Sichuan in China. However, only a few researches are focused on the specific effects of solar radiation heat in this area. Therefore, based on a practical residential building in Western Sichuan and the survey data, the heating load during the day and night in a heating season under different working conditions are compared in this paper. The influence of solar radiation on the heating load of residential buildings in Western Sichuan is analyzed, and the correctness of the simulation software is verified by experiments. The results show that the solar radiation will greatly increase room base temperature in the daytime. In a heating season, the heating load of the building increases by 26.12% without considering solar radiation heat. During the day (9:00 to 18:00) and night (18:00 to 9:00), the heating load increases by 35.69% and 19.80%, respectively. Besides, solar radiation mainly affects the south exterior wall in a north-south residential building. The heating load of south rooms is 27.52% less than north rooms, with 35.92% less during the day and only 22.08% less during the night.

Novel solar-powered photovoltaic/thermoelectric hybrid power source

A photovoltaic (PV) module converts solar radiation into electric power. Solar collectors convert directly solar heat into hot water (not electric power). A thermoelectric generator (TEG) directly converts solar heat into electric power. Thus, this study combines a PV module with some TEGs to directly convert both solar radiation and solar heat into electric power. The result is a novel solar-powered PV/thermoelectric hybrid power source. The output power of a TEG module is very small when temperature difference between its two surfaces (hot and cold) ranges below about 50C∘. As a result, TEGs cannot be used in low-grade heat harvesting applications such as solar heat harvesting. This study also solves this defect, so that, the mentioned temperature difference is raised by utilizing a two-phase closed thermosiphon (TPCT) heat pipe, a concentrator and a radiator. A prototype of the proposed PV/thermoelectric hybrid power source has been constructed, and experimental results obtained from its operation under realistic conditions are given. The novelties and contributions of this research work can be outlined as below:The PV/thermoelectric hybrid power source directly converts both solar radiation and solar heat into electric power.The technique used to design and construct the PV/thermoelectric hybrid power source enables utilizing TEGs in low-grade heat harvesting, in particular, solar heat harvesting.The technique provides a dc bus with constant voltage, so other power generation devices such as fuel cell and wind power generation system can be easily added to the system by connecting them to the dc bus through a converter.The technique uses a high-efficient maximum power point tracking (MPPT) method which is a modified and high-efficient version of perturb and observe (P&O) method with adaptive and variable step size.

A Numerical Investigation on Microphysical Properties of Clouds and Precipitation over the Tibetan Plateau in Summer 2014

In order to improve our understanding of microphysical properties of clouds and precipitation over the Tibetan Plateau (TP), six cloud and precipitation processes with different intensities during the Third Tibetan Plateau Atmospheric Science Experiment (TIPEX-III) from 3 July to 25 July 2014 in Naqu region of the TP are investigated by using the high-resolution mesoscale Weather Research and Forecasting (WRF) model. The results show unique properties of summertime clouds and precipitation processes over the TP. The initiation process of clouds is closely associated with strong solar radiative heating in the daytime, and summertime clouds and precipitation show an obvious diurnal variation. Generally, convective clouds would transform into stratiform clouds with an obvious bright band and often produce strong rainfall in midnight. The maximum cloud top can reach more than 15 km above sea level and the velocity of updraft ranges from 10 to 40 m s−1. The simulations show high amount of supercooled water content primarily located between 0 and −20°C layer in all the six cases. Ice crystals mainly form above the level of −20°C and even appear above the level of −40°C within strong convective clouds. Rainwater mostly appears below the melting layer, indicating that its formation mainly depends on the melting process of precipitable ice particles. Snow and graupel particles have the characteristics of high content and deep vertical distribution, showing that the ice phase process is very active in the development of clouds and precipitation. The conversion and formation of hydrometeors and precipitation over the plateau exhibit obvious characteristics. Surface precipitation is mainly formed by the melting of graupel particles. Although the warm cloud microphysical process has less direct contribution to the formation of surface precipitation, it is important for the formation of supercooled raindrops, which are essential for the formation of graupel embryos through heterogeneous freezing process. The growth of graupel particles mainly relies on the riming process with supercooled cloud water and aggregation of snow particles.