Lower Surface Temperature Research Articles

Thermal analysis on the evaporation of fluid covered by porous media subjected to ultrasound and air jet impingement

The porous layer subjected to air jet is set above fluid passing through heating surface to control its thickness and avoid drying up, as well as ultrasound is introduced at upstream to enhance convection in flowing channel, in which heat flux can be dispersed in convection between fluid and heating surface as well as evaporation on the outside surface of porous cover to the outside. Local thermal equilibrium (LTE) occurs in porous cover, and the effect of sound pressure from ultrasound on liquid fluid is introduced according to acoustic theory. Brinkman–Forchheimer extended Darcy equations and k-ε turbulent model together with the above formulas are employed to describe the heat transfer in fluid covered by porous media subjected to ultrasound and air jet impingement. The effects of ultrasound power and frequency, fluid layer thickness as well as porosity and particle size in porous cover on heat transfer are investigated. The performance evaluation criteria (PEC) is defined to evaluate thermal characteristics in the cases with ultrasound than those without. The 35.7% rise ratio of heat transfer coefficient in the mode with ultrasound power of 50 W happens than that without. The higher ultrasound power and lower frequency of ultrasound cause lower heating surface temperature and larger heat transfer coefficient. The simulations agree with available published experiment data. All results of this study can be considered into utilization of ultrasound and porous layer to enhance heat transfer in flowing channel.

Revolutionary integrated cool roofing technologies system for attic temperature reduction in buildings

The cooling load is the most prominent building energy consumption. The roof's poor thermal resistance effect causes buildings in the tropical climate to receive high solar heat that afterwards transfer to the attic before entering the living space. Eight roof design models were built and evaluated under 90 min of solar radiation exposure to noon-time level solar intensity to determine their cooling effect at noon every day. Significantly, the fantastic cool roof system was proven effective with a structural heat gain reduction of 85.5%. The reduction of concrete's density from 2500 kg/m3 to 1100 kg/m3 with lightweight foamed concrete technology allowed the roof's lower surface temperature to decrease by 21.6% (66.3–52.0 °C). Adding a highly solar reflective insulation system with roof ventilation reduced the structural heat gain by up to 33.3%. The combination effects of lightweight foamed concrete roof tile, hollow longitude sections, thermal reflective coating, reflective insulation system, and renewable solar-powered fans reduce the peak attic temperature from 42.8 °C to 32.2 °C.

Mid-IR Observations of IRAS, AKARI, WISE/NEOWISE, and Subaru for Large Icy Asteroid (704) Interamnia: A New Perspective of Regolith Properties and Water Ice Fraction

(704) Interamnia is one of the largest asteroids located in the outer main-belt region, which may contain a large amount of water ice underneath its surface. We observe this asteroid using 8.2 m Subaru telescope at mid-infrared wave bands and utilize a thermophysical model for realistic surface layers to analyze mid-infrared data from Subaru along with those of IRAS, AKARI, and Wide-field Infrared Survey Explorer (WISE)/NEOWISE. We optimize the method to convert the WISE magnitude to thermal infrared flux with temperature-dependent color corrections, which can provide significant references for main-belt asteroids at a large heliocentric distance with low surface temperature. We derive best-fitting thermal parameters of Interamnia—a mean regolith grain size of μm, with a roughness of and rms slope of deg, thereby producing thermal inertia ranging from 9 to 92 Jm−2 s−1/2 K−1 due to seasonal temperature variation. The geometric albedo and effective diameter are evaluated to be and , respectively, being indicative of a bulk density of 1.86 ± 0.63 g cm−3. The low thermal inertia is consistent with typical B/C-type asteroids with D ≥ 100 km. The tiny regolith grain size suggests the presence of a fine regolith on the surface of Interamnia. Moreover, the seasonal and diurnal temperature distribution indicates that thermal features between the southern and northern hemispheres appear to be very different. Finally, we present an estimation of volume fraction of water ice of 9%–66% from the published grain density and porosity of carbonaceous chondrites.

Description and Genomic Analysis of the First Facultatively Lithoautotrophic, Thermophilic Bacteria of the Genus Thermaerobacter Isolated from Low-temperature Sediments of Lake Baikal.

Members of the genus Thermaerobacter belong to the phylum Firmicutes and all isolates characterised to date are strictly aerobic and thermophilic. They were isolated from a mud sample of the Challenger Deep in the Mariana Trench, hydrothermal vents, and silt compost. A novel thermophilic, facultatively lithoautotrophic bacteria of the genus Thermaerobacter, strain PB12/4term (=VKM B-3151T), with a metabolism that is uncharacteristic of the type species, was isolated from low-temperature surface sediments near the Posolsk Bank methane seep, Lake Baikal, Russia. The new strain grows with molecular hydrogen as electron donor, elemental sulfur, and thiosulfate as electron acceptors, and CO2/[Formula: see text] as carbon source. The genome of strain PB12/4term consists of one chromosome with a total length of 2.820.915 bp and the G+C content of the genomic DNA was 72.2%. The phylogenomic reconstruction based on 120 conserved bacterial single-copy proteins revealed that strain PB12/4term belongs to the genus Thermaerobacter within in the class Thermaerobacteria, phylum Firmicutes_E. The strain PB12/4term is closely related to Thermaerobacter subterraneus DSM 13965 (ANI=95.08%, AF=0.91) and Thermaerobacter marianensis DSM 12885 (ANI=84.98%, AF=0.77). Genomic and experimental data confirm the ability of the Thermaerobacter PB12/4term pure culture to facultatively lithotrophic growth, which is provided by the presence of [NiFe]hydrogenase enzymes that are absent in T. marianensis DSM 12885 and T. subterraneus DSM 13965. The data obtained on the physiological and biochemical differences of strain PB12/4term provide a deeper insight into the species diversity and functional activity of the genus Thermaerobacter.

Splashing characteristics and dynamics of drops impingement on ultracold surfaces

Drop impingement on low-temperature surfaces is a common phenomenon in various situations, such as the icing process on airplanes and spray impingement in internal combustion engines in an ultracold environment. Numerous literatures have reported the spreading and icing characteristics during the cold surface impingement but the characteristics and dynamics of the splashing process under a similar circumstance have not been comprehensively investigated. In this work, the drop splashing process on low-temperature surfaces is investigated both experimentally and theoretically. By employing high-speed shadowgraphy, we find the drop splashing pattern gradually changes from prompt splash to corona splash as the surface temperature decreases from 20 °C to −39 °C because of the physical property changes of the liquid in the drop. The splashing threshold decreases monotonically with surface temperature. The critical Weber number to trigger splash decreases from 441 to 235 and 288 respectively on aluminium and PMMA surfaces as surface temperature drops from 20 °C to −30 °C. A semi-theoretical model to predict the splashing threshold is established based on Riboux and Gordillo’s theory, while the suction force is found dominating the lift forces that induce the levitation of the liquid film. Temperature characteristics of the surrounding air and drop are simplified based on a simulation analysis. The model shows fair agreement with the experiments on both aluminium and PMMA surface.

Innovative light-coloured porous asphalt for low-impact pavements: A laboratory investigation

In recent years, research is pushing toward more sustainable solutions in the road sector such as cool pavement and eco-friendly paving components. Cool pavements are advanced pavement technologies characterized by lower surface temperature thanks to the use of light-coloured binders and an open-graded structure. In this framework, the present study intends to provide a laboratory characterization of two different open-graded wearing courses produced with Construction and Demolition waste (CDW) aggregates and virgin aggregates and with a transparent resin-based binder. The final aim of the research is to provide scientific evidence on the possible application of the adopted resin-based transparent binder with light-coloured aggregates for open-graded wearing courses in order to minimize the Urban Heat Island phenomenon. The results show that the addition of 50% of CDW aggregates to the porous asphalt enhances the abrasion resistance and the mechanical performance of the mixture.

Economic and exergy analysis of passive solar still incorporated with an additional condensing surface material beneath the top glazing to enhance the productivity.

The main bottleneck haunting the wide dissemination of solar still is its poor yield per unit area. This study aims to overcome the above bottleneck by augmenting the yield of SS by increasing the surface area available for condensation by incorporating an acrylic chamber filled with water beneath the top glass surface. The solar still incorporated with acrylic basin (ACSS) was operated in two different methodologies and its performance was ascertained and compared with the conventional passive solar still (CPSS). The surface area available for condensation in CPSS and ACSS operating in two different modes were 0.52 m2 and 0.87 m2, respectively. The efficiency of the CPSS and ACSS operated in mode I was 24.28% and 28.94% respectively. On the other hand, the efficiency of the CPSS and ACSS operated in mode II was 26.61% and 31.29% respectively. The rate of evaporation of water from the basin of ACSS operated in mode II is enhanced by 42.74% when compared to the CPSS. The increment in evaporation rate can be attributed not only due to the increment in surface area available for condensation but also due to the supply of hot water present in the acrylic chamber to the basin of the ACSS operated in mode II depending on its yield for every half an hour. Meanwhile, replenishment of water in the acrylic chamber every 30min by water at 30°C, abets in reducing the lower surface temperature of acrylic chamber which aid in increasing the temperature difference between water in the basin and lower surface of acrylic chamber. Thus, the productivity of ACSS operated in mode II is higher than that of CPSS by 17.59%.

Plasma Surface Engineering of Natural and Sustainable Polymeric Derivatives and Their Potential Applications.

Recently, natural as well as synthetic polymers have been receiving significant attention as candidates to replace non-renewable materials. With the exponential developments in the world each day, the collateral damage to the environment is incessant. Increased demands for reducing pollution and energy consumption are the driving force behind the research related to surface-modified natural fibers (NFs), polymers, and various derivatives of them such as natural-fiber-reinforced polymer composites. Natural fibers have received special attention for industrial applications due to their favorable characteristics, such as low cost, abundance, light weight, and biodegradable nature. Even though NFs offer many potential applications, they still face some challenges in terms of durability, strength, and processing. Many of these have been addressed by various surface modification methodologies and compositing with polymers. Among different surface treatment strategies, low-temperature plasma (LTP) surface treatment has recently received special attention for tailoring surface properties of different materials, including NFs and synthetic polymers, without affecting any of the bulk properties of these materials. Hence, it is very important to get an overview of the latest developments in this field. The present article attempts to give an overview of different materials such as NFs, synthetic polymers, and composites. Special attention was placed on the low-temperature plasma-based surface engineering of these materials for diverse applications, which include but are not limited to environmental remediation, packaging, biomedical devices, and sensor development.

Semi-flexible pavement with glass for alleviating the heat island effect

This study investigated the feasibility of developing a semi-flexible pavement (SFP) by utilising recycled waste glass to partially replace ingredients in traditional asphalt pavement and the effect on performance. The results established that partially replacing cement with 15% glass powder or zeolite powder does not compromise the mechanical performance and significantly improves the reflectance. Compared with traditional asphalt pavement, the SFP with a glass block content of 40% has excellent high-temperature stability, lower surface temperature, reduced thermal conductivity, and improved thermal resistance. The glass-containing SFP was confirmed to be capable of alleviating the urban heat island effect via simulation.

Simulating spatial variations of lithospheric folding in the south polar terrain of Enceladus

The South Polar Terrain (SPT) of Saturn's moon Enceladus is a young, heavily lineated region that has been shown to be actively venting cryovolcanically. A set of roughly evenly spaced, subparallel fissures, collectively known as the Tiger Stripes, cut across the SPT and is the source of the venting. Additionally, thermal observations demonstrated anomalously high heat flow coming out of the whole SPT in general, and the Tiger Stripes in particular; total heat power out of the region has been estimated to be ∼5–18 GW, more than what can be supplied by equilibrium tidal heating and suggesting temporal variability in the thermal structure of the SPT. Between the Tiger Stripes are a series of closely spaced, short wavelength (1.1 km) linear features generally following the trend of the Tiger Stripes, which has been interpreted as folding of a surface layer undergoing compression. In addition, periodic ridges and troughs (5 km wavelength) found in the zone rimming the SPT have been interpreted recently as contractional features. Here, we simulate the formation of both types in order to constrain the thermal conditions required for their formation. Reproducing the shorter wavelength features necessitates high surface temperatures (185 K) and high heat flows (400 mW m−2), results consistent with past work. The long wavelength features need lower surface temperatures (130K) and heat flows (100 mW m−2), which demonstrates a spatial variability heat of lost from the center to the periphery of the SPT.

Detection of Geocryological Conditions in Boreal Landscapes of the Southern Cryolithozone Using Thermal Infrared Remote Sensing Data: A Case Study of the Northern Part of the Yenisei Ridge

This paper discusses the potential of using infrared remote sensing data to determine geocryological conditions in the northern part of the Yenisei Ridge in Russia. Landsat-8 thermal infrared images and land surface data were used for our analysis. The obtained thermal characteristics were compared with vegetation indices calculated for the period of active vegetation growth along several surface transects. Surface observations included geobotanical descriptions, phytomass estimations, measurements of thickness of the seasonally thawed layer, and visual identification of different effects of permafrost on the components of the taiga landscape. The obtained surface temperatures differed depending of forest type due to their bio-productivity characteristics on sporadic permafrost as the most important factor of forest growth conditions within the southern part of the cryolithozone. The differences in the thermal characteristics are due to varying degree of permafrost influence on boreal vegetation growth. The surface temperature was used as indicator to quantify the relationship between the latent heat and the sensible heat fluxes for the corresponding landscape. The areas with higher surface temperatures were usually characterized by higher sensible heat flux due to lower evapotranspiration of the plant canopy. The forest types with the highest evapotranspiration had usually the lowest surface temperatures. Such forest types are also the most fire-resistant systems, and have the highest water-discharge potential. This is characteristic of the forests under the lowest impact of permafrost (thawed soils or the presence of the permafrost layer at lower depths). Such types of forests have higher ecosystem service potential (e.g., fire-resistance and stock formation).

The Electro-Thermal Antimicrobial Carbon Surface

Microorganisms on the surface are important contributors to producing a serious threat to global public health. Herein, we introduce an electro-thermal antimicrobial carbon surface. When a 9 V direct voltage was applied to the carbon surface, the carbon fibre surface temperature reached 80 °C. This electro-thermal-based antimicrobial carbon surface showed outstanding inactivation performance, exhibiting a potent inactivation rate of ∼99.99% against Gram-positive bacteria ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Staphylococcus epidermidis</i> ) and Gram-negative bacteria ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Escherichia coli</i> ) in just 10 min. Interestingly, under the same temperature, when alternating voltages were applied, electro-thermal antimicrobial performance was enhanced, resulting in a >6.0 log reduction against both Gram-positive and Gram-negative bacteria. In addition, under alternating voltage applied conditions, this excellent electro-thermal-based antimicrobial performance was maintained even at a lower surface temperature (50 °C).

Diagnosing Near-Surface Model Errors with Candidate Physics Parameterization Schemes for the Multiphysics Rapid Refresh Forecast System (RRFS) Ensemble during Winter over the Northeastern United States and Southern Great Plains

Abstract During the winter of 2020/21 an ensemble of FV3-LAM forecasts was produced over the contiguous United States for the Winter Weather Experiment using five physics suites. These forecasts are evaluated with the goal of optimizing physics parameterizations within the future operational Rapid Refresh Forecast System (RRFS) in the Unified Forecast System (UFS) realm and for selecting suitable physics suites for a multiphysics RRFS ensemble. The five physics suites have different combinations of land surface models (LSMs), planetary boundary layer (PBL) parameterizations, and surface layer schemes, chosen from those used in current and possible future operational systems and likely to be supported in the operational UFS. Full-season evaluation reveals a persistent near-surface cold bias in the U.S. Northeast from one suite and a nighttime warm bias in the southern Great Plains in another suite, while other suites have smaller biases. A representative case is chosen to diagnose the cause for each of these biases using sensitivity simulations with different physics combinations or modified parameters and verified with additional mesonet observations. The cold bias in the Northeast is attributed to aspects of the Noah-MP LSM over snow cover, where Noah-MP simulates lower soil water content, and thus lower thermal conductivity than other LSMs, leading to less upward ground heat flux during nighttime and consequently lower surface temperature. The nighttime warm bias found in the southern Great Plains is attributed to overestimation of vertical mixing in the K-profile-based eddy-diffusivity mass-flux (K-EDMF) PBL scheme and insufficient land–atmospheric coupling from the GFS surface layer scheme over short vegetation. A few key parameters driving these systematic biases are identified.

Low temperature ammonia synthesis from atomic N and water on rutile TiO2(110)

We have investigated the formation of ammonia (NH3) from atomic N and water (H2O) on a rutile(R)-TiO2(110) surface using the temperature-programed desorption method. The formation of NH3 can be detected after coadsorption of atomic N and H2O on the R-TiO2(110) surface, desorbing from the 5-fold coordinated Ti4+ (Ti5c) sites at about 400 K, demonstrating that the NH3 formation on R-TiO2(110) is feasible at low surface temperature. During the process, both hydroxyl groups at the bridging oxygen rows and H2O on the Ti5c sites contribute to the formation of NH3, which are affected by H2O coverage. At low H2O coverage, the direct hopping of hydrogen atoms may be the dominant process for hydrogen transfer; while H2O-assisted hydrogen atoms diffusion may be preferred at high H2O coverage. Our result will be of significant help to get a deeper insight into the fundamental understandings of hydrogenation processes during the NH3 synthesis.

Adsorption dynamics of O2 on Cu(111): a supersonic molecular beam study.

We have studied the adsorption of O2 on Cu(111) using supersonic molecular beam techniques. For incident energies ranging between 100 and 400 meV, we have determined the sticking probability as a function of angle of incidence, surface temperature, and coverage. Initial sticking probabilities range from near 0 to 0.85 with an onset near 100 meV, making Cu(111) considerably less reactive than Cu(110) and Cu(100). Normal energy scaling applies and reactivity increases appreciably over the entire range of surface temperatures from 90 to 670 K. A strictly linearly decreasing coverage dependence on sticking precludes adsorption and dissociation via an extrinsic or long-lived mobile precursor state. We cannot exclude that sticking also occurs molecularly at the lowest surface temperatures. However, all tell tales from our experiments suggest that sticking is predominantly direct and dissociative. Comparison to earlier data shows implications for the relative reactivity of Cu(111) vs. Cu/Ru(0001) overlayers.

Blending Recycled High-Density Polyethylene HDPE (rHDPE) with Virgin (vHDPE) as an Effective Approach to Improve the Mechanical Properties

The mechanical properties of virgin/recycled high-density polyethylene (HDPE) blends over the complete concentration range was thoroughly investigated in this work. In particular, a focus was made on the long-term properties via mechanical fatigue. Two different mixing methods, namely powder mixing (dry blending) and extrusion mixing (melt blending), were used to determine the effect of processing conditions on the tensile and fatigue behavior of the blends after compression molding. It was found that both tensile (modulus, ultimate strength) and fatigue performances were improved with increasing vHDPE content. Based on the obtained data, a correlation between the blends composition and mechanical properties is reported. Moreover, it was observed that increasing the vHDPE content led to slower crack propagation rate, probably due to less defects (contamination) in the blends. Finally, a negligible difference in mechanical properties (fatigue resistance) between both mixing approaches was observed, but samples produced via powder mixing showed less viscous dissipation (heat generation) as the vHDPE content increased, leading to lower surface temperature rise which can be an advantage for specific applications.

Use of Hybrid Mineral Filler with High Emissivity in Asphalt Mixture for Cooling Road Pavements

Road asphalt pavements cover a high percentage of urban size and contribute to heat islands. This study proposed a new method to cool asphalt pavement by incorporating a kind of hybrid mineral filler (HMF) with high emissivity into a reference asphalt mixture prepared with limestone mineral filler (LMF). The physical, emissive, solar reflective, and rheological properties of asphalt mastic and the thermal performances of asphalt mixture were covered to investigate the possibility of the proposed strategy. From Fourier transform infrared spectrum test, it can be found that HMF was physically blended with asphalt. The emissivity results show that HMF increased the emissivity of asphalt mastic from 0.9204 to 0.9820. The asphalt mastic containing HMF had similar solar reflectance with the control one. In addition, HMF could enhance the rutting resistance of asphalt mastic according to the results of multiple stress creep recovery tests. When HMF replaced LMF, the thermal conductivity of the asphalt mixture with HMF increased by 0.26 W/(m·K) (the reference value was 1.72 W/(m·K)). The combined effect of high emissivity and thermal conductivity led to a lower surface temperature (i.e., -5.4 °C) in the tests. The results of this study demonstrate that HMF is a potential material to cool asphalt pavements.

Analysis of predicted mean vote-based model predictive control for residential HVAC systems

Model Predictive Control (MPC) is an advanced process control method that has attracted much attention in building heating, ventilation, and air conditioning (HVAC) systems. This paper analyzes the optimal precooling performance in residential buildings using MPC with two different comfort indices, namely, temperature and predicted mean vote (PMV). It first formulates, for each comfort index, an optimization problem that accounts for different factors, such as weather, home thermal condition, prediction horizon, time-of use (TOU) utility rate, and rated cooling capacity. The problem is then solved, resulting in an MPC strategy that determines the HVAC on/off control signal and minimizes energy cost over a receding time horizon while maintaining thermal comfort. The energy performance difference between temperature-based and PMV-based MPC strategies is subsequently investigated, especially in light of the interior wall surface temperature and under different combinations of the factors. Extensive simulation results demonstrated that the proposed MPC strategies are adaptive and their performances depend primarily on weather, home thermal condition, and prediction horizon, while the impact of TOU utility rate and rated cooling capacity is relatively small. Because the PMV-based MPC strategy can take advantage of the lower interior wall surface temperature due to precooling, it resulted in 8–45% cost savings for the scenarios investigated and an average increase of 0.042–0.113 in the absolute value of the PMV index compared to the temperature-based MPC strategy.

S3P– Innovative Surface Treatment to Increase the Wear Resistance of Stainless Steel Components*

Abstract Austenitic and duplex stainless steels are used in a variety of industries due to their high corrosion resistance. However, this is countered by a high coefficient of friction and thus a limited wear behaviour, which restricts the technical application possibilities. Coatings or conventional hardening processes, such as solution nitriding above 1000 °C, offer a certain reduction of these wear phenomena, but are associated with the risk of delamination and/or loss of corrosion properties. In addition, the hardening effect is limited for austenitic and duplex grades. The low temperature surface hardening process below 500 °C offers the possibility to overcome these limitations. In this article the technology of this process is explained. In addition, research results show the positive influence of this treatment on the lifetime of components made of corrosion resistant steels. As a future outlook, possible properties and applications for the prospective increasing number of hydrogen applications are explained.

Measurement and CFD analysis of a local radiant cooling solution

This paper entails an empirical and computational assessment of the air flow field in the close proximity of a vertically positioned radiant cooling panel. This radiant cooling solution differs from the conventional large-area radiant cooling systems (e.g., ceiling panels). It involves rather small-sized vertical panels positioned close to occupants. Moreover, the panels are designed so as to manage potential surface condensation of water vapor via integrated drainage elements. Hence, the panels can be operated with relatively low surface temperatures. The low panel surface temperature and its proximity to the occupants are intended to compensate for the potential lower cooling power due to the relatively small panel size. In this paper, we specifically explore the air flow field close to the local radiant cooling panel via laboratory measurements and CFD (Computational Fluid Dynamics). Thus, possible issues regarding discomfort due to draft and turbulence risk close to the radiant panel can be examined. To this end, a prototypical local radiant cooling panel was installed in a mock-up office room of a laboratory. During the experiments, the air flow speed was measured and simulated at several heights (between 10 and 110 cm from the floor) and distances (ranging from 1 to 50 cm from the radiant panel). The results allow for the evaluation of the draft discomfort risk as well as the reliability of CFD in reproduction of the measurement results. A further step involved the numeric analysis of the effect of the human model on the air flow patter.