Solar Radiation Heat Research Articles

Highly Tough and Reliable Poly(Amic Acid) with Ballistic Impact-Resistance through Modulation of Hydrogen Bonding Interactions.

Poly(amic acid) (PAA) materials as the precursor of polyimide generally show remarkably poor mechanical properties, thus limiting their application as the engineering plastics. In this study, it is demonstrated that the mechanical properties of PAA materials can be improved significantly for tens of folds with breaking strength >50MPa, Young's modulus >400MPa, and elongation at break >300% by incorporation of 20% (mol%) poly(propylene glycol) (PPO) soft segments. The optimization for suitable hard-soft composition with 20% PPO and the existence of various hydrogen bonds with different binding energies can dissipate energies efficiently, which simultaneously improve the material strength and toughness. In addition, PAA82 films exhibit excellent tolerance toward cyclic stretch, and have the capability to resist various harsh conditions including solar radiation testing (1sun), heat (85°C), alkalinity (pH 10), and acidity (pH 4) over one month. Noted that PAA82 films can be laminated with Kapton films, which show excellent resistance to ultrahigh (200°C) and ultralow temperature (-196°C). The laminated film also exhibits bulletproof property with a thickness of 6mm. The strategy via modulation of hard-soft compositions and hydrogen bonds in PAA materials shows great potentials to improve the mechanical properties of polymeric materials.

Determination of the maximum allowable active powerflow in the section taking into account the thermal conditions of power transmission lines

Subject of research: This paper assesses the possibility of introducing into the task of calculating maximum and emergency allowable active power flow, taking into account the thermal modes of overhead lines when planning electric power regimes. 
 Purpose of research: determine the effect of thermal processes in power lines on the maximum allowable active power flow in controlled sections of electric power systems.
 Methods and objects of research: Such factors influencing active power flow as ambient air temperature, which is currently corrected by the Russian Power System Operator, wind speed, solar radiation and direct heating from flowing current are considered. Simulation of steady state flow in the software package RastrWin3 and Mathcad for a 2-bus scheme with mode only taking into account the ambient temperature and the calculations of steady state flow were already taking into account variations in weather parameters, taking into account possible restrictions on the maximum load due to the modes of operation of the power system (technical feasibility generating equipment was not taken into account in the work under consideration).
 Main results of research: the result of calculation, it is clearly seen that when taking into account the thermal conditions of overhead power lines, the allowable active power flows differ by 1626 % from the values determined only when taking into account the ambient temperature.

Characteristics of office lighting energy consumption and its impact on air conditioning energy consumption

The energy consumption of office buildings has increased sharply since the 21st century with the increasing urbanization coverage. At this stage, the energy consumption of office buildings in China mainly comes from air conditioning and lighting. This paper obtains the regression equation of natural lighting illumination and radiant heat gain under different curtain conditions through experiments and simulations, and gives the theoretical calculation process of curtain regulation of office thermal and light environment and energy consumption. DeST and Ecotect software were used to analyze the thermal and light environment and energy consumption of the office. The results show that setting curtains in the room can effectively improve the indoor thermal light environment, the higher the transmittance of curtains the lower the lighting energy consumption, the higher the number of high temperature hours of natural room temperature and the greater the radiant heat gain. The room with thick curtains has the lowest energy consumption for air conditioning in summer, followed by the room with thin curtains, and the room without curtains has the highest energy consumption for air conditioning. The room without curtains has the lowest energy consumption for artificial lighting, the room with thin curtains has the second lowest, and the room with thick curtains has the highest electricity consumption for artificial lighting. The air conditioning energy consumption accounts for the main building energy consumption, followed by the lighting energy consumption. After setting curtains in the office, the air conditioning energy consumption caused by the solar radiation heat entering the room through the exterior windows is smaller than the lighting energy consumption caused by artificial lighting. Therefore, the installation of internal shading with moderate transmittance and good thermal insulation performance can make the energy saving of lighting and air conditioning energy consumption reach the optimal value.

Effectively using heat to thermally enhance pressure retarded osmosis

Thermal energy from solar radiation and industrial waste heat is abundant and can be used to improve the performance of membrane processes for water treatment and power generation. In this study, we investigate the concept of using heat to thermally enhance pressure retarded osmosis for improved energy recovery from salt gradients. A laboratory apparatus is used to demonstrate performance at temperatures between 20 and 50 °C, and improvements in water flux and power density of up to 110 % are observed. Temperature of the feed solution is found to be more important than draw temperature. A finite element model is experimentally validated and used to identify what transport dynamics are responsible for the priority to heat feed. It is found that a hot feed solution produces a warmer membrane (thereby encouraging higher permeability and mitigated polarization), and this principally because the feed boundary offers little thermal resistance as it is typically well-mixed during pressure retarded osmosis. Finally, a new metric of effectiveness is introduced to evaluate power increases relative to the change in temperature. It is found that although operation at higher temperatures may yield higher power, operation at low temperatures of ~30 °C may represent a more effective use of thermal energy.

Effect of the material color on optical properties of thermochromic coatings employed in buildings

Thermochromic materials can adjust their formal reflectivity in response to changes in ambient temperature, so they offer a means of achieving seasonal thermal control and have been a reasonable choice to enhance the solar radiation heat in winter and lower the solar radiation heat in summer. To optimize thermochromic coatings to meet the application requirement on architectural surface color, the effect of the material color was studied on optical properties of thermochromic coatings under two transition temperatures of 25 °C and 33 °C. A measurement system was designed to analyze the reflectivity spectra and solar reflectivity of thermochromic coatings in both colored and colorless phases. Experimental results show that all samples exhibited a significant increase in reflectivity from the colored phase to the colorless phase especially in the 1300 nm–1600 nm and 1900 nm–2100 nm wavelengths. The global reflectivity of the thermochromic coatings could be increased by 3.17%–10.68% under 25 °C and 7.22%–18.23% under 33 °C. From the view of evaluating the optical properties, the purple-blue and dark-green colors are respectively the best choices for thermochromic coatings. The experimental data proposed the efficient reference for application of thermochromic materials in buildings.

Long-term temperature acceleration effect of solar radiation heating on chloride transport in the CRTS III multilayer structure

The service life of high-speed railway track structures located in coastal areas may be shortened by chloride erosion due to the marine environment. This study aims to simulate chloride transport within the track structure by boundary condition models based on high-precision climate data and structural damage. The established numerical models consider various factors, including structural damage, historical exposure data of air temperature and relative humidity, temporal resolutions, solar radiation history, and the deposition rate of atmospheric chloride. The main conclusions are as follows: The maximum vertical temperature gradient of the track slab is roughly 81K/m, and the daily average temperature differences between air and surface concrete in July and February are around 9.6°C and 4.8°C, respectively. The chloride flux boundary derived from the chloride deposit rate is nearly 1 × 10-9mol/(m2s) to 10 × 10-9mol/(m2s) under a marine atmospheric environment. Step functions of daily average and monthly average temperature can improve almost the same prediction accuracy of chloride diffusion, and increasing the monthly average temperature curve by 10°C can roughly estimate the upper limit of temperature acceleration.

Assessment of the dynamic thermal behaviour of a test room using computer simulations and experimental measurements

People spend most of the time indoors and adequate comfort level in buildings is fundamental for their well-being and productivity. These issues can be investigated using both simulation models and experimental measurements in dedicated laboratories or in real buildings. The numerical and experimental approaches need to be combined in order to overcome the limitations of each one. This paper presents the application of a detailed numerical model to the CORE-CARE laboratory built at the University of Padua, a test room employed for indoor environmental quality (IEQ) evaluations. The HVAC plant consists of a mechanical ventilation unit and radiant systems for space heating and cooling. Each radiant surface presents different constructive characteristics and can operate independently. The test room is a novelty in this panorama, as it was integrated in an existing building, as a room for regular use. The impossibility of controlling external disturbances makes the dynamic modelling of the room extremely important, for the laboratory control and knowledge. For this reason, the test room behaviour in response to different HVAC system settings and external disturbances is analysed. Two experimental campaigns were carried out both in the heating and cooling seasons, activating one surface at a time, in order to both validate the model and set-up the transient thermal behaviour of the laboratory. In summer, three experimental set-ups were arranged: closed blinds, opened blinds and presence of a thermal dummy. The data analysis highlights that the North surface exhibits the fastest response in both seasons, whereas the floor is the slowest due to its inertia. In summer, the active surface equilibrium temperature is closer to the water supply temperature for responsive and massive surfaces, and it rises with incoming solar radiation and thermal dummy heat gain. The cooled floor enhances the space's thermal stratification. Simulation results show that the model reproduces the system's real dynamics, with a maximum RMSE of 2.3 and 1.9 °C for the North surface and air temperature.

Synergetic Enhancement of Seebeck Coefficients and Electrical Conductivity in Flexible Liquid Crystal Composites

The development of thermoelectric (TE) devices, which convert thermal gradient into energy, was motivated by the immense amount of heat wasted from solar radiation and industrial heat dissipation. Polymer-based organic thermoelectric (OTE) materials have garnered much interest owing to their distinctive advantages, including low thermal conductivity, minimal toxicities, low cost, and superior mechanical elasticity. However, the TE performance of these organic materials is mainly limited due to their low Seebeck coefficient and poor electrical conductivity. In this work, we simultaneously improve the Seebeck coefficients and electrical conductivity of polyvinylidene fluoride (PVDF) polymer and single-wall carbon nanotube (SWCNT)-based composites by incorporating a liquid crystal (LC). This is attributed to the thermodiffusion of ions and the formation of stable and efficient conductive channels with LC incorporation. The concentration of LC is suitably tuned, which results in an increment of ∼42% Seebeck coefficient and ∼72% electrical conductivity compared to the reference PVDF/SWCNT composite. The tensile strain curve shows that the durability of the composite samples has increased by incorporating the LC. Also, a flexible thermoelectric generator (TEG) device consisting of eight composite legs is constructed, which shows an open circuit voltage and output power of 35.7 mV and 46.1 nW, respectively, at a temperature difference of 60 K. The findings show that LC-based SWCNT/PVDF composites exhibit superior TE potential and provide a new route for fabricating flexible TE devices.

Diurnal Cycle and Dipolar Pattern of Precipitation Over Borneo During the MJO: Linear Theory and Nonlinear Sensitivity Experiments

AbstractThe precipitation anomaly over Borneo features a dipolar pattern under the influence of the Madden‐Julian Oscillation (MJO). To understand the formation mechanisms of this pattern, a linear theory is developed to study the factors controlling its diurnal cycles and the dipolar pattern. The theory predicts that the prevailing wind is primarily responsible for the asymmetry over an idealized island, while the topography plays a critical role in the leeward convergence and convection asymmetry. The results are largely consistent with the observed composites of the dipole at Borneo. Nonlinear cloud‐permitting simulations are further conducted to test the effects of island topography and solar radiative heating in different MJO phases. The results show that the island topography can cause the mesoscale flow to split around the mountain due to the topographic blocking, and favor the development of the lee side sea breeze. These processes strengthen the low‐level convergence and convection at the leeside of the island during the late afternoon and night, which is very important to the formation of island dipolar precipitation anomaly. In contrast, the inland convergence is weakened and the dipole disappears when the terrain is flattened. The diurnal cycle of solar insolation is the dominant factor driving the land‐sea breeze circulation, which intensifies the island convection at the leeside. These results indicate that the MJO wind anomaly, island topography and solar insolation play distinct roles in the formation of the dipolar pattern of Borneo precipitation.

Study on heat flow transfer characteristics and main influencing factors of waxy crude oil tank during storage heating process under dynamic thermal conditions

In response to the energy conservation and emission reduction targets proposed by China's Fourteenth Five-Year Plan, it is necessary for oilfield enterprises to achieve the purpose of reducing energy consumption and carbon emissions of crude oil storage under the premise of ensuring safe production of oil depots. As the preferred oil storage facility for crude oil depots, the internal heat flow transmission process of storage tanks plays a vital role in the overall energy consumption of oil depots. In this paper, a three-dimensional theoretical model of the heating process of large waxy crude oil tank storage is established, and the influence law of the circumferential effect of the coil on the heating process of waxy crude oil is put forward. The external environment influence area, the internal temperature rise heat flow influence area and the transition area are put forward. The multi-nonlinear regression method is innovatively used to establish the main influencing factor model for each influence area so as to realize the quantitative characterization of the influence mechanism between the heat flux at the tank boundary and the dynamic thermal environment and the variable physical properties parameters of crude oil. The results show that the convective heat transfer of oil in the tank bottom area is greatly influenced by the circumferential effect of the coil, and the circumferential effect of the coil is enhanced with the gradual proximity of the coils on both sides, and the low temperature area at the tank bottom is obviously improved. The heat loss of the storage tank is mainly concentrated at the boundary of the tank. According to the change of heat flux in each boundary area, the external environment influence area, the internal heating heat flow influence area and the transition area are divided. Among them, the top of the storage tank forms an external environmental impact area dominated by solar radiation heat transfer, supplemented by natural convection of temperature difference, and the bottom of the storage tank forms an external soil impact area dominated by heat conduction to the external soil. Due to the effect of the thermal insulation layer, the influence of the external dynamic thermal environment on the position of the tank wall is weakened, and only the influence area of the internal temperature rise heat flow dominated by the natural convection of crude oil is formed. At the same time, there is a transition area with different thickness between the internal and external influence areas, which is affected by the external dynamic thermal boundary conditions and the physical properties of crude oil. The internal heat transfer direction is different, which causes the influence weight of each factor to fluctuate, and with the reduction of the external dynamic thermal environment, the transition area becomes the external condition influence area.

Arctic warming contributes to increase in Northeast Pacific marine heatwave days over the past decades

The frequency and duration of marine heatwaves have been increasing with ocean warming due to climate change. In particular, the Northeast Pacific has experienced intense and extensive marine heatwaves since the late 1990s – characteristically called “the Blob”. Here, an investigation of satellite-derived and reanalysis data supported by idealized coupled model experiments show that Arctic warming plays an important role in the increase in Northeast Pacific marine heatwave days during boreal summers. Strong Arctic warming has acted to change the atmospheric circulation pattern over the Northeast Pacific and reduce the low-level cloud fraction from late spring to early summer. We show that the enhancement of solar radiative heat fluxes and reduced latent heat loss over a relatively large area has favored an increase in sea surface temperatures and marine heatwave days. An idealized model experiment performed here, designed to isolate the impact of Arctic warming, supports this hypothesis. The projected changes of Arctic climate on the occurrence of marine heatwaves should be considered in climate change adaptation and mitigation plans.

Simulasi WinAir4 (CFD) Terhadap Pengaruh Kecepatan Dan Aliran Udara Di Dalam Ruang Kuliah Universitas Nusa Nipa Maumere

Comfort can be provided from a building, inseparable from the existence of the building itself in the context of an environment that is limited by consideration of natural factors. In an effort to achieve comfort in buildings in tropical climates such as Indonesia, especially the city of Maumere, with characteristics of wind speed, humidity and relatively high air temperature and solar heat radiation can reach levels outside the human comfort zone. This study compares the speed and direction of wind flow in different lecture halls, seen from the level of height, direction and contour of the ground. The method used is data taken using equipment measured in the field and the results are simulated using WinAir4 from ECOTEC. The results obtained are the effect of altitude level, direction and contour orientation on wind speed and air flow in the design of the lecture hall in relation to thermal comfort.

Ecological technology of green building in the initial stage of design based on BIM technology

At present, the whole world is faced with a common topic, that is, the contradiction between energy consumption, serious fog, the continuous rise of PM2.5, plastic waste, white pollution and other environmental pollution and the worldwide energy shortage. In this paper, aiming at the international new town construction project in Xigu District, Lanzhou, Revit software is used to establish a physical model for data integration and integrated management of the geometric information of building space, functional information of building space, building materials and other related data information of the project, and an analysis model for the scheme design of the residential building of the project is obtained, and ecological and technical factors such as energy consumption analysis, lighting analysis, indoor lighting analysis, solar radiation analysis, shading and thermal comfort analysis of the project location are analyzed. The research shows that the thermal performance, energy consumption simulation analysis and hourly heat gain/loss analysis of the envelope in the coldest weather in the local area show that the heat conduction of the envelope is small under the three conditions of structural design (case A), standard limit (case B) and hypothetical construction (case C), which indicates that the solar radiant heat is mainly related to the material performance of the external window when the heat transfer coefficient of the roof is close, and the heat gain and loss between regions has little change.

Thermal regulation mechanism of air-drying shelter to indoor environment of earth buildings located in Turpan basin with extremely dry and hot climate conditions

This study investigates the thermal regulation mechanism of air-drying shelter of earth buildings located in Turpan basin to indoor thermal environment under the extremely dry and hot climate condition. Firstly, a field measurement lasting for three days was performed to investigate the thermal effect of air-drying shelter on indoor thermal condition. The measured results indicated that air-drying shelter provides the shaded space and natural ventilation to reduce the internal surface temperature of the roof and further improve the indoor thermal comfort in the hot summer. Then, a series of numerical studies on the effects of design parameters of air-drying shelter on indoor environment of earth building in Turpan basin were performed. The selected design parameters of air-drying shelter included air-drying shelter to room height ratio, thickness of carved walls, thickness of air-drying shelter's roof and hole to wall area ratio. The simulated results demonstrated that hole to wall area ratio of the carved walls is considered as an important design parameter of air-drying shelter, and increasing hole to wall area ratio of carved walls could increase solar radiation heat gain of roof, leading to increasing internal surface temperature of roof and indoor air temperature.

Spatial and temporal variability of the solar radiation heat flux in streams of a forested catchment

Solar radiation is generally the largest contributing flux to the heat budget of streams and its estimation is crucial to predict stream water temperature with process-based models. The objective of this research is to quantify the spatial (between-site comparison of different stream sizes, within-site comparison at the reach scale) and temporal (seasonal, daily and hourly scales) variability in the transmission coefficient, which represents the proportion of incoming solar radiation reaching streams. We measured solar radiation at an open site with a meteorological station and at microclimate sites located in three streams of various sizes in the Miramichi River basin (Canada). During the summer, the percentage of incoming daily solar radiation reaching a stream varied from 8% in a small headwater stream (Trib) to 43% in a medium-sized stream (CatBk) and was close to 100% in a wide river (LSWM). We observed the largest variability between transmission coefficients for different stream sizes (range of variation = 92%) due to very different canopy closures, followed by variability at the reach scale between lateral positions (range = 21% between left and right banks) and between longitudinal positions (range = 11% between upstream and downstream sites), as measured at the medium-sized stream. Temporal variability was greatest at the seasonal scale where the transmission coefficient varied by 23% between May and September at the small headwater stream. The hourly variability of the transmission coefficient (i.e. associated with different solar angles) surpassed daily variability (i.e. associated with different cloud cover conditions), with coefficients of variation computed at the hourly time scale three to five times greater than at the daily time scale. Overall, this research offers insight regarding the handling of spatial and temporal variability of solar radiation which should provide further insight to improve process-based stream temperature models.

AN ARTIFICIAL NEURAL NETWORK AND TAGUCHI INTEGRATED APPROACH TO INVESTIGATION OF HEAT TRANSFER AND PRESSURE DROP IN THE SOLAR AIR HEATER

In this paper, an artificial neural network (ANN) and Taguchi method integrated approach to investigation of the Nusselt number (Nu) and friction factor (f) with circular ring turbulators under solar radiation has been used. The integrated ANN and Taguchi method was applied to examine the effect of three different parameters − pitch ratio (PR), hole number (HN), and Reynolds number (Re) − on the Nusselt number (Nu) and friction factor (f) under solar radiation heat flux (I). The Taguchi experimental design was conducted using L9 orthogonal array to determine the factor levels of the optimal design. The optimum parameters affecting Nu and fin a solar air heater (SAH) were determined as A3B1C1 and A3B3C3, respectively. The contribution ratios for the test parameters affecting Nu and f were evaluated by using ANOVA analysis. It was shown that the Re number has an effect on Nu with 40.03% contribution ratio, whereas HN has a contribution ratio of 57.24% on f in SAH. Also, Nu and f empirical equations for correlations were obtained with the help of the ANN model. The results of estimation of the ANN model were compared with those of experimens and the obtained results showed a good correlation coefficient (R2) by finding between 0.9950-0.9987 for the test data set.

Sustainable underground environment integrating hybrid ventilation, photovoltaic thermal and ground source heat pump

Sustainable underground environments face ‘high temperature, humidity and pollution’ from heavy internal loads and warming climate. Relying on mechanical ventilation and ignoring the ‘soil–building–atmosphere’ coupling cause energy wastage and soil thermal imbalance. This study discusses the sustainable design of multienergy coupling and hybrid ventilation for underground environments. Furthermore, this study proposes a novel system combining hybrid ventilation, photovoltaic thermal (PVT) and ground source heat pump (GSHP) to integrate energies from the atmosphere, shallow and deep soil and solar and waste heat. On the one hand, PVT pipes and solar radiation heat solar chimneys to produce stable thermal pressure ventilation. On the other hand, GSHP efficiently exchanges heat in deeper soil to regulate the indoor environment and cool the PVT pipes. TRNSYS coupled with CONTAM implements ‘electric–heat–airflow’ coupling simulations to assess various system performances. This system's performance in different climates is analysed from soil thermal balance, energy efficiency, hybrid ventilation and PVT generation. This study hopes to offer inspiration and a design method of multienergy coupling for exploring sustainable underground environments.

Comparative analysis of environmental standards to install a rooftop temperature monitoring station

Urban climate influences economic activities and the health and safety of urban residents. Therefore, monitoring temperature in urban areas is important. However, owing to the lack of space for an appropriate observation site, an automatic weather station (AWS) was installed on a building rooftop. The rooftop installation can indicate temperature differences depending on the intensity of strong solar radiation and radiant heat of the building, and wind speed. Therefore, in this study, we aimed to provide observation standards for measuring rooftop temperature according to the optimal rooftop material and observation height. Specifically, an AWS was installed on the rooftop of the Gochang Standard Weather Station (GSWO), Jeollabuk-do Province, to observe the urban climate in South Korea and establish suitable weather standards. Different temperatures, optimum surface materials, and optimum heights for measuring the temperature at the rooftop of GSWO were investigated and compared over 1 year. The temperature recorded after installing a palm mat on the rooftop was more similar to that observed in the grassland. Furthermore, the installation height of the temperature sensor of 2.5–3.0 m for the palm mat and 3.5–4.0 m for concrete was found to be the optimal height for observing temperature at the rooftop.

The flashy red color of the red velvet mite Balaustium murorum (Prostigmata: Erythraeidae) is caused by high abundance of the keto-carotenoids, astaxanthin and 3-hydroxyechinenone.

The red velvet mite, Balaustium murorum (Hermann), is a pollenophagous free-living mite with a flashy red body. This mite occurs in early spring and lives on sunny surfaces of human-made structures, such as concrete. Hence, it is inevitably exposed to a harsh environment due to solar ultraviolet-B (UV-B) radiation and radiant heat, which cause oxidative stress via the production of reactive oxygen species. The spider mite Panonychus citri that resides on upper leaf surfaces accumulates synthesized keto-carotenoids to protect against oxidative stress. Therefore, we evaluated carotenoid composition in the red pigment of B. murorum. To identify major carotenoids, we performed a high-performance liquid chromatography analysis of intact and de-esterified pigments of B. murorum females. The flashy red pigments of B. murorum consisted of the highly abundant keto-carotenoids astaxanthin and 3-hydroxyechinenone (60 and 38% of major carotenoids, respectively), and a small amount of β-carotene (2%). Although P. citri is an astaxanthin-rich species, the astaxanthin concentration (per protein) in B. murorum is 127-fold that in P. citri. Due to their high antioxidant activities, those keto-carotenoids probably contribute to the survival of B. murorum in the harsh environment caused by solar UV-B radiation and radiant heat in inorganic habitats.

Designing a Binjai City Performing Arts Building with a Tropical Architecture Approach

Binjai is one of the National Centers for Activities (PKN) and includes in the National Strategic Urban Area of ​​MeBiDangRo. While based on RPI2JM 2015-2019, there are fifteen ethnicities in Binjai. This diversity is undoubtedly a capital in developing its traditional arts and culture. However, based on the GRDP, the arts industry has not yet become a source of income, so this research purposes on how to design a better performing arts building and how to apply tropical architecture to the design as support, facilities, and awards for activists and performing arts enthusiasts as a source of income from the tourism sector. The research stage begins with determining the design location, considering the elements and requirements, collecting data, and analyzing data to produce a design concept. Binjai has a tropical climate, so Binjai Performing Arts Building adapts a tropical architectural approach where thermal comfort, air circulation, and the use of materials are selected properly such as maximizing many openings to support air circulation and lighting, using overstacks and secondary skin as an aesthetic shading, and minimizing solar heat radiation into the building. Moreover, this research produces a proportional design for a Performing Arts Building.