Average Surface Temperature Research Articles

Investigation of heat transfer and damage characteristics of high pressure abrasive water jet impacting high temperature sandstone

ABSTRACT Efficient breaking of hard mineral rocks is an important prerequisite for deep metal mining. In order to study the rock breaking mechanism of abrasive water jet erosion of high-temperature hard rock in deep ground, the temperature deformation evolution law during the process of jet impact on rocks was simulated and experimentally studied. The results show that the distribution of jet pressure, jet velocity, and jet turbulent kinetic energy near the residence point of the jet impingement wall is generally high in the middle and low in the outside. The heat transfer distance r on the rock surface is approximately (1.5–2.0) times the nozzle diameter, and the heat transfer distance inside the rock is (1.0–1.5) times the nozzle diameter. The maximum heat flux density at the jet cooling wetting boundary can reach 450 W/mm2. Within 0–3 seconds of the erosion process, the average surface temperature sharply decreases and exhibits a downward trend of jet stagnation point radiating outward. The radius of jet cooling influence gradually increases. Due to the impact cooling effect, tensile stress is generated at the top of the rock sample, and the tensile stress in the lower part of the rock is converted into compressive stress. With the increase of jet pressure and treatment temperature, the area and range of erosion pits significantly increase, and there is a significant phenomenon of thermal cracking around the erosion pits. The research conclusion can provide new ideas and basis for hydraulic breaking of high-temperature hard rocks in deep ground.

Three Gorges Dam: Potential differential drivers and trend in the spatio-temporal evolution of the change in snail density based on a Bayesian spatial–temporal model and 5-year longitudinal study

BackgroundSnail abundance varies spatially and temporally. Few studies have elucidated the different effects of the determinants affecting snail density between upstream and downstream areas of the Three Gorges Dam (TGD). We therefore investigated the differential drivers of changes in snail density in these areas, as well as the spatial–temporal effects of these changes.MethodsA snail survey was conducted at 200 sites over a 5-year period to monitor dynamic changes in snail abundance within the Yangtze River basin. Data on corresponding variables that might affect snail abundance, such as meteorology, vegetation, terrain and economy, were collected from multiple data sources. A Bayesian spatial–temporal modeling framework was constructed to explore the differential determinants driving the change in snail density and the spatial–temporal effects of the change.ResultsVolatility in snail density was unambiguously detected in the downstream area of the TGD, while a small increment in volatility was detected in the upstream area. Regarding the downstream area of the TGD, snail density was positively associated with the average minimum temperature in January of the same year, the annual Normalized Difference Vegetation Index (NDVI) of the previous year and the second, third and fourth quartile, respectively, of average annual relative humidity of the previous year. Snail density was negatively associated with the average maximum temperature in July of the previous year and annual nighttime light of the previous year. An approximately inverted “U” curve of relative risk was detected among sites with a greater average annual ground surface temperature in the previous year. Regarding the upstream area, snail density was positively associated with NDVI and with the second, third and fourth quartile, respectively, of total precipitation of the previous year. Snail density was negatively associated with slope.ConclusionsThis study demonstrated a rebound in snail density between 2015 and 2019. In particular, temperature, humidity, vegetation and human activity were the main drivers affecting snail abundance in the downstream area of the TGD, while precipitation, slope and vegetation were the main drivers affecting snail abundance in the upstream area. These findings can assist authorities to develop and perform more precise strategies for surveys and control of snail populations.Graphical

Identifying determinants for the seropositive rate of schistosomiasis in Hunan province, China: A multi-scale geographically weighted regression model.

Schistosomiasis is of great public health concern with a wide distribution and multiple determinants. Due to the advances in schistosomiasis elimination and the need for precision prevention and control, identifying determinants at a fine scale is urgent and necessary, especially for resource deployment in practice. Our study aimed to identify the determinants for the seropositive rate of schistosomiasis at the village level and to explore their spatial variations in local space. The seropositive rates of schistosomiasis were collected from 1714 villages or communities in Human Province, and six spatial regression models including ordinary least squares (OLS), spatial lag model (SLM), spatial error model (SEM), geographically weighted regression (GWR), robust GWR (RGWR) and multiscale GWR (MGWR) were used to fit the data. MGWR was the best-fitting model (R2: 0.821, AICc:2727.092). Overall, the nearest distance from the river had the highest mean negative correlation, followed by proportion of households using well water and the annual average daytime surface temperature. The proportions of unmodified toilets showed the highest mean positive correlation, followed by the snail infested area, and the number of cattle. In spatial variability, the regression coefficients for the nearest distance from the river, annual average daytime surface temperature and the proportion of unmodified toilets were significant in all villages or communities and varied little in local space. The other significant determinants differed substantially in local space and had significance ratios ranging from 41% to 70%, including the number of cattle, the snail infested area and the proportion of households using well water. Our study shows that MGWR was well performed for the spatial variability of schistosomiasis in Hunan province. The spatial variability was different for different determinants. The findings for the determinants for the seropositive rate and mapped variability for some key determinants at the village level can be used for developing precision intervention measure for schistosomiasis control.

Interannual variability of sea surface temperature at the polar latitudes of the Atlantic Ocean

The general regularities and regional differences in the interannual variability of the sea surface temperature in the polar latitudes of the Atlantic Ocean are revealed according to the OI SST reanalysis data for period 1982—2017. The reanalysis contains daily average sea surface temperature values at the nodes of a regular grid 0,25°×0,25°. In this work, areas where the ice concentration did not exceed
 90 % were analyzed. In both polar basins, the position of areas with a high level of sea surface temperature
 interannual variability qualitatively coincides with the position of intense currents. The maximum values of
 linear sea surface temperature trends are observed in areas of the maximum level of interannual variability,
 while the trends in long-term sea surface temperature variability in the Arctic and Antarctic are noticeably
 different. Significant positive sea surface temperature trends prevail in the Atlantic sector of the Arctic.
 Significant negative trends have been identified only off the northeastern coast of Greenland and north of the Arctic Current. The sea surface temperature decrease on a long-term scale in this area is associated with an increase of cold water transport by the East Greenland and Arctic currents, which are formed as a result
 of the intensive melting of Arctic ice observed in recent decades. In the Atlantic sector of the Antarctic, on the contrary, significant negative sea surface temperature trends prevail. In the Arctic, the maximum values of positive sea surface temperature trends are observed in August—September during the period of maximum warming of surface waters and minimum concentration of drifting ice. In the Antarctic, the maximum negative sea surface temperature trends in absolute value are observed from August to October, during the period of surface water cooling and maximum ice concentration.

ANALISIS POTENSI ENERGI LISTRIK DI GEDUNG UMPAR MENGGUNAKAN PANEL SURYA 100WP

Electricity plays a very important role in everyday life. Most human activities are related to the use of electrical energy, including in the Campus environment. Technological advances have resulted in an increase in the consumption of electrical energy and this has resulted in reduced reserves of fossil energy sources as a result of being used up and causing emissions that can affect the global climate. The energy transition from the use of fossil energy to new and renewable energy is one solution to overcome this. Solar Power Plant (PLTS) is an alternative energy solution that is environmentally friendly that can be developed on campus. This is also supported by Indonesia's geographical location which has a very high intensity of sunlight. In this study, an analysis of the potential of electrical energy generated at Universitas Muhammadiyah Parepare Building was carried out. The research was conducted by measuring the surface voltage and temperature of solar panels for 20 days. The test was carried out for 7 hours from 10.00 WITA to 16.00 WITA. Voltage and temperature measurements were carried out in 1 hour intervals. The test results show that the average voltage value generated by solar panels is 21.31 volts. The highest average voltage value was generated at 13.00 WITA, which was 21.82 volts with an average surface temperature of 37.79 oC

Marine bird mass mortality events as an indicator of the impacts of ocean warming

The frequency and severity of marine heatwaves (MHWs), an emergent property of global warming, has led to large-scale disruptions to marine ecosystems. As upper trophic species, marine birds reflect shifts in trophic structure and stability; therefore, a sharp increase in marine bird mortality is a clear signal of ecosystem impact. In this study, we analyzed 29 yr (1993-2021) of beached bird monitoring data (~90000 surveys) to identify marine bird mortality events throughout the Northeast Pacific and Alaska, USA, and examined linkages to ocean-climate variability. Mortality events were documented throughout the study period, but massive events (>500 km in extent, >10 carcasses km-1) occurred infrequently (n = 5), with an unprecedented sequence from 2014-2019. Event characteristics, including encounter rate (carcasses km-1), duration, and spatial extent, were positively related to prior-year averaged sea surface temperature anomaly, with event magnitude (product of encounter rate, extent, and duration) displaying a step-like transition, increasing 5-fold between +0°C and +1°C above baseline (1981-2010) temperatures. Mortality events occurred more frequently following MHWs, and a common sequence of mortality events (at 1-6 and 10-16 mo after heatwave onset) was observed in the California Current large marine ecosystem following 3 prolonged MHW events. Following the second wave of mortality at 10-16 mo after MHW onset, a consistent 16 mo period of depressed carcass encounter rates ensued. Given continued global warming, our results point to more frequent large-scale mortality events and the potential for a new lower carrying capacity for marine birds in the Northeast Pacific.

THERMAL AND DAYLIGHTING PERFORMANCE OF TRANSPARENT CONCRETE IN PENANG, MALAYSIA

Modern technology studies and research developments have enhanced the quality and innovation of concrete. Transparent concrete is concrete that has light-transmitting properties which transmit light through the optical fibre. Optical fibres are reinforced in the conventional concrete mixture from one face to another face, which allows direct light to transmit through it. Daylighting factor is one of the fundamental qualities of the energy efficiency of a building. The thermal performance is also crucial to providing comfort to the building occupants. The literature studies cover the light transmittance and thermal performance of transparent concrete. Selected literature studies are reviewed based on the related topic, Asian countries, and countries with a similar climate to Malaysia. This research applies quantitative method where it was focus on experimental study to transparent concrete. The overall result indicates improvement on light transmission and thermal performance as the plastic optical fibre increased compared to conventional concrete. The total average outdoor surface temperature of transparent concrete shows a difference of 0.989°C lower than conventional concrete. The total average temperature different between conventional concrete and transparent concrete (560 optical fibre) are 0.9°C. This experiment's significant contribution is that using more plastic fibre optic reduces thermal conductivity and heat gain while allowing for greater daylighting. Finally, transparent concrete shows effectiveness on light transmission and thermal resistance where it can contribute to building industry on green building and sustainable design. However, the further studies on thermal performance with longer duration is required to analyses the thermal heat loss.

Scenario of climate change impact on insect pests in India

The climate change has been intensified the risk of climate dependent crop production. Increase in temperature can reduce crop duration, increase crop respiration rates, alter photosynthesis process and affect the survival and proliferation of pest populations. The importance of climate and weather events to the distribution of insects and their population dynamics has long been recognized. Insects are poikilothermic in nature and are directly under the control of temperature for their growth. The duration of insect life cycle is altered under increased temperature and elevated carbon dioxide concentrations resulting in variable number of generations per year. The elevated carbon dioxide concentrations are mediated through enhanced photosynthesis in plants for phytophagous insects’ growth and development. Several insect pests, that were important in the past or the minor pests are likely to become more devastating with global warming and climate change. Insect pests cause an estimated annual loss of 13.6% globally and 23.3% in India. Losses due to insect pests are likely to increase as a result of change in crop diversity and climate change. An increase of 0.4ºC average surface temperature over past century in India has led to crop insect pests losses increase from 3.0% during the pre-green revolution period to 50% during the post-green revolution period. The changes of insect pests losses has been increased up to 32%. Considerable knowledge is available on the effects of weather and climatic events on insect pests in India. But concerned to the impact of climate change on insect pests studies are in lag phase. A major portion of the cultivated areas of India covered under rainfed. The rainfed agriculture is directly reciprocal to the climate. So, any changes in the state of climate may cause crop failure due to biotic and abiotic stresses of climatic vagaries. Therefore, detailed study of the climate change scenario, its impact on insect pest management and formulation of coping strategies are of paramount importance to reduce the risk of crop failure. This paper attempt to analyse the review of reported studies on the scenario of climate change impact on insect pests in India to reduce the risk of strategy for effective insect pest management.

The Economic Impact of the Global Warming

Global warming is a phenomenon that causes the average surface temperature of the Earth to rise due to an increase in greenhouse gases. This rise in temperature has significant implications for the global economy, as it affects various sectors and regions differently. This paper reviews the literature on how global warming impacts the economy, focusing on four main aspects: gross domestic product (GDP), inflation, energy industry, agricultural, production output in different fields and tourism. The article also explores the cost-effectiveness of enacting strategies to alleviate and adjust to the financial consequences of global warming. The research finds that global warming could reduce GDP by up to 18% by 2050 if no action is taken, and that the costs of mitigation and adaptation are likely to be lower than the costs of inaction. The paper concludes that global warming is a systemic risk that requires urgent and coordinated action from governments, businesses, and individuals.

Design Impacts on Ram Air Vane Cooling in an Ultra-Compact Combustor

Abstract The ultra-compact combustor (UCC) aims to decrease the length of gas turbine combustors using a unique design geometry which wraps a combustion chamber around the central axial flow. This distinctive design enables an out of the box type of cooling scheme to be investigated for the turbine inlet vanes, termed the hybrid guide vane (HGV) in the UCC. The leading edge of the HGV experiences only compressor exit air as combustion products do not interact with the vane upstream of the 14% axial chord location. Previous studies were conducted which computationally evaluated the viability of taking in freestream flow through the HGV stagnation region for use as coolant. Based on these studies, a six vane HGV was manufactured which incorporated a solid vane and five hollow vanes. Each of these vanes incorporated different features to vary the size of the internal plug, trailing edge exit, and film cooling holes. In the present study, the cooled HGV was experimentally analyzed using pressure, thermocouple, and infrared (IR) thermography measurements to evaluate internal coolant flowrates and pressure loss along with cooling performance. Furthermore, the vanes were compared to isolate the impact of design differences on vane cooling. It was found that the location of the internal plug and incorporation of film cooling holes had a minor impact on coolant flow and cooling. Additionally, results showed exit area had the largest impact on surface temperature and coolant mass flow where the largest exit area allowed less restricted coolant flow resulting in the lowest average surface temperature. However, completely blocking the exit slot forced coolant to exit only through film cooling holes, stagnating the majority of the internal flow, resulting in surface temperatures higher than the uncooled, solid vane.

Construction of multifunctional surface to fabricate wood-derived cellulose electrothermal composites with flame retardant and hydrophobic performance for harsh operating conditions

As a renewable resources, wood is limited to functional applications due to its defects of moisture deformation, water swelling, and flammability. At present, wood-derived cellulose electrothermal composites has excellent Joule heating performance, but it faces the dilemma of limited operating environment. To this end, multiwall carbon nanotubes (MWCNTs) were deposited on the wood-derived cellulose skeleton (WCS) surface by multiple dipping-drying cycles to obtain electrothermal performance. Ammonium polyphosphate and trichloro (1 H,1 H,2 H,2 H-tridecafluoro-n-octyl) silane were then sequentially deposited on MWCNTs/WCS surface to obtain better flame retardant and hydrophobic performance. The resultant multifunctional MWCNTs/WCS (MMW) achieved an average surface temperature of 119.3 °C at 4.0 V and retaining repeatability under power ON/OFF cycles. The residue amount of MMW was increased by 105.6% and the heat release capacity was decreased by 92.9% compared with WCS, which exhibited an excellent flame retardancy. Moreover, MMW had a water contact angle of 145.6° and showed durable hydrophobicity in harsh operating conditions. It is believed that MMW with electrothermal, flame retardant, and hydrophobic properties has promising applications in thermal therapy, aircraft deicing, indoor heating, and smart electronic wallpaper.

Promoting fountain behaviors with cone surface structures under impinging jets

Increased heat generation in newer generations of electronic devices necessitates increasingly aggressive thermal management techniques. In automotive applications, jet impingement is particularly attractive for the cooling of power electronics, as integration in the radiator flow loop requires few added components. Arrays of impinging jets are effective at cooling heated surfaces to relatively uniform temperatures, as increased heat transfer is achieved both under and between jets. Under the jets, fluid motion naturally limits the thermal boundary layer, while interactions between jets create a plume or fountain of fluid that departs the surface. To maximize utility of this approach, fountain development must be promoted and spent fluid must be effectively managed. In this study, an angled confining wall and conical surface modifications under each water jet were analyzed. When using an angled wall, crossflow effects on the downstream jets were significantly reduced, suggesting improved performance, particularly for larger arrays. The cone modifications were able to promote fountain and secondary fountain behaviors, improving performance across the surface. In particular, the secondary fountain was seen to reduce a hot spot on the surface. Under a flat confining wall, average surface temperature rises were reduced by 3.5 to 7.5%, despite the area only being increased by 1 to 3%, indicating that 60 to 78% of the thermal improvement is caused by enhanced heat transfer coefficients. The results suggest that the modifications could be effective in hot spot applications and in achieving a uniform surface temperature, potentially improving device performance and increasing lifespan.

Four-Dimensional Variational Data Assimilation and Sensitivity of Ocean Model State Variables to Observation Errors

The use of Four-Dimensional variational (4D-Var) data assimilation technology in the context of sea dynamics problems, with a sensitivity analysis of model results to observation errors, is presented. The technology is applied to a numerical model of ocean circulation developed at the Marchuk Institute of Numerical Mathematics, Russian Academy of Sciences (INM RAS), with the use of the splitting method and complemented by 4D-Var data assimilation with covariance matrices of background and observation errors. The variational data assimilation involves iterative procedures to solve inverse problems so as to correct sea surface heat fluxes for the model under consideration. An algorithm is formulated to study the sensitivity of the model outputs, considered as output functions after assimilation, to the observation errors. The algorithm reveals the regions where the output function gradient is the largest for the average sea surface temperature (SST) in a selected area, obtained by assimilation. In the numerical experiments, a 4D variational problem of SST assimilation for the Baltic Sea area is solved.

MHD mixed convection and heatlines approach of nanofluids in rectangular wavy enclosures with multiple solid fins

Two dimensional wavy walls rectangular cavity with inclined magnetohydrodynamic has been examined in mixed convection configurations. Triple fins arranged in the upwards ladder were filled within alumina nanoliquid in the cavity. Vertical sinusoidal walls were heated, and the other side was kept cold while both horizontal walls were kept adiabatic. All walls were motionless except the top cavity that was driven to the right. The diversified range of control parameter in Richardson number, Hartmann number, number of undulations, length of the cavity has been performed in this study. The analysis was simulated using finite element method by employing the governing equation formula, and the results were delineated in the form of streamlines, isotherms, heatlines, and comparisons on several relationships between the local velocity in the y-axis line of 0.6, local and average Nusselt number along the heated surface and dimensionless average temperature. The findings revealed that high concentration nanofluids boost the rate of heat transfer without the need to apply any magnetic field. Results found that the best heat mechanisms are natural convection with significant-high Richardson number as well as constructing two waves on the vertical walls in the cavity.

Urbanization Heat Flux Modeling Confirms It Is a Likely Cause of Significant Global Warming: Urbanization Mitigation Requirements

Recent ground-based measurements find the magnitude of the urbanization effect on the global average annual mean surface air temperature corresponds to an urbanization contribution of 12.7%. It is important to provide modeling to help understand these results as there are conflicting concerns. This study models the global warming contribution that urbanization heat fluxes (UHF) can make due to anthropogenic heat release (AHR), and solar heating of impermeable surface areas (ISAs), with additional secondary effects. Results help explain and support ground-based observations. Climate models typically omit anthropogenic heat release (AHR) as warming estimates are below 1%. In agreement, the baseline assessment in this paper has similar findings. However, in this study, the methods of climate amplification estimates (MCAE) with data-aided physics-based amplification models are used. When the MCAE are applied at the global and microclimate levels that consider greenhouse gases (GHGs), feedback, and other secondary effects; the results show that AHR fluxes can amplify, increasing to have an estimated global warming (GW) influence of 6.5% from 1950 to 2022 yielding a 0.9% decade−1 increase. This increasing rate due to energy consumption is found as anticipated to be reasonably correlated to the increasing population growth rate over this time. Furthermore, using the MCAEs, this paper studies heat fluxes assessment due to solar heating of unshaded impermeable surfaces including likely secondary amplification effects. Impermeable surface areas (ISAs) such as asphalt roads, roofs, and building sides have been reported with high land surface contact temperatures (LSCTs) relative to non-ISAs and significantly found to contribute to urbanization warming. Results indicate that high-temperature unshaded impermeable surfaces (including building sides) are estimated to average around 10–11 °C above the earth’s ambient temperature of 14.5 °C (showing albedo ISA estimates between 0.133 and 0.115 respectively); the ISA heat fluxes with secondary effects are estimated to have about a GW influence of 6.5%. This is broken down with average contributions of 4.0% from urban ISAs and 2.5% from rural ISA heat fluxes. Asphalt road ISA heat fluxes are estimated to have about a 1.1% global warming influence. Then the total UHF effect from ISAs and AHR with secondary effects is assessed in modeling to yield a combined average GW influence of 13% helping to confirm ground-based measurement results. Several key adjustment values were used for shading, cloud coverage, and rural-to-urban ISA ratios. Microclimate GHGs and related water vapor feedback (WVF) were assessed to increase urban warming by about 50%. As well an assessment of water vapor and radiation increases from UHF is provided. This study also shows the need to incorporate urbanization heat fluxes with secondary effects into climate models and indicates the necessity for Paris Agreement urban heat flux mitigation goals. Results also found that given average climate conditions, it is possible to mitigate much of the UHI effect with an albedo increase of 0.1 that is anticipated to lower the average impermeable surface temperatures by about 9 °C. Studies show this can be accomplished with cost-effective cool roads and roofs. Although roads are only estimated to occupy 14% of ISAs, changing roads from asphalt to concrete-type surfaces would improve reflectivity by about a factor of 5 and is estimated to mitigate about 5.5% of global warming. Unfortunately, the current overuse of black asphalt on pavements and roofs is highly dangerous to our environment causing UHI increases in heatwaves, excessive temperatures, and global warming issues and should be banned. Asphalt usage also reduces opportunities for solar geoengineering of urbanization.

Indicators of thermal comfort and nitrogen digestibility as a function of digestible arginine: lysine ratios in the diet of laying Japanese quails raised in hot weather

The objective with this study was to determine the influence of the digestible arginine: lysine ratio in the diet of laying Japanese quails raised in hot weather on the physiological variables of thermoregulation, time in tonic immobility, behavior and nitrogen utilization. A total of 240 laying quails (Coturnix coturnix japonica) with 40 weeks of age were used in a completely randomized design with five treatments and six replications containing eight quails per experimental unit. The studied digestible arginine: lysine ratios were 110%; 120%, 130%, 140% and 150%, for 63 days divided into three periods of 21 days each. There was a quadratic effect (p < 0.05) for the variables average surface temperature, average body temperature, core to surface thermal gradient, ambient to surface temperature gradient observed in the morning. In the afternoon, a quadratic effect (p < 0.05) of the arginine: lysine ratio was observed for variables average surface temperature, average body temperature, core to surface thermal gradient, ambient to surface thermal gradient, back temperature, head temperature and respiratory frequency. There was no significant effect (p > 0.05) of arginine: lysine ratios on the frequency of behaviors, except drinking and panting (p < 0.05), for which 130% ratio provided the lowest frequencies of these behaviors. There was a quadratic effect (p < 0.05) for the parameters of nitrogen retention, nitrogen excreted and nitrogen retention efficiency. Nitrogen intake and excreta moisture were not influenced by the different relationships studied (p > 0.05). The 130% arginine: lysine ratio corresponding to 0.131 g/kg/feed of arginine improves physiological responses related to thermoregulation and decreases the expression of behaviors correlated to heat stress, also meeting the best estimated ratio for nitrogen retention in the diet of quails laying Japanese raised in hot weather.

Space Cooling Energy Potential of Domestic Cold Water before Household Consumption in Cold-Climate Regions

Space cooling energy consumption in residential buildings has tripled globally over the past three decades, leading to a significant increase in greenhouse gas (GHG) emissions and building operating costs. To reduce building cooling energy consumption, cooling energy can be recovered from domestic cold water (DCW) for space cooling by circulating DCW through thermally massive walls (herein “DCW-wall”) before regular household consumption (e.g., showers). This approach is more effective in cold climate regions since the DCW is cooler in these regions, yet its engineering design and effectiveness have not been evaluated previously. This study evaluated the cooling potential of DCW-walls in different operation scenarios (e.g., inlet temperatures, zone temperatures, and piping configurations). A typical DCW usage pattern and a daily amount of 1200 L were selected for evaluation. Three-dimensional transient thermal simulations were used to obtain the water outlet temperatures, average wall surface temperatures, and cooling potentials. The results showed that a DCW wall with a spiral piping configuration and DCW inlet at 12 °C can deliver 21.92 MJ of cooling energy daily to a zone at 25 °C. This amount of free energy can cover up to approximately 11% of the annual cooling energy demand of a four-person dwelling in Toronto, Canada, which has a warm and humid summer.

Multi-objective topology optimization and thermal performance of liquid-cooled microchannel heat sinks with pin fins

The optimized structures for the liquid-cooled microchannel heat sinks with different pin-fin arrays were designed via using the topology optimization method for the better performance, including minimization of the flow energy dissipation and the average temperature of the bottom surface, aiming to facilitate the more efficient design of microchannel heat sink for electronic chips’ cooling. The heat transfer and flowing performance was simulated with steady-state incompressible Navier-Stokes equation and the energy equation. Based on the rational approximation of material properties (RAMP) method, the mathematical optimization model for heat sink was established according to the multi-objective function. The Galerkin finite element method (GFEM) was employed to calculate the flow and heat transfer system. Furthermore, the globally convergent method of moving asymptotes (GCMMA) was adopted to deal with the mathematical optimization problem as the optimization method. The entropy generation analysis and comprehensive heat transfer factor were employed to evaluate the performance of the conjugate heat transfer problem of 3D microchannel heat sinks with various pin-fin structures. The calculation results reveal that the multi-objective optimal structure has good heat transfer performance, and the temperature distribution of the optimized structure is more uniform. As the same pumping power, the comprehensive heat transfer efficiency of the optimized inline and staggered pin-fin arrays increases by 31.20% and 32.18% compared to the smooth rectangular channel. Compared with the cylindrical pin-fin configuration with the same heat transfer area, the entropy generation rates of the optimized inline and staggered pin-fin configurations decrease by 4.67% and 4.25%, respectively. The results can provide theoretical basis and application support for the electronic chip cooling technology.

Thermal analysis of concrete bricks-embedded phase change material: A case study under hot weather conditions

This research experimentally examines the thermal behaviour of concrete brick-based PCM layer/capsules during severe hot summer days in southern Iraq. Three bricks were fabricated in which one brick was integrated with a PCM layer (BL) and another integrated with PCM capsules (BC), while the third was left bare without PCM (BR) for comparison. The thermal performance of bricks was assessed considering the inner and outer surface temperature difference, decrement factor, time lag and average surface temperature fluctuation reduction. Besides, the mechanical strength decline of each brick was investigated to show their applicability in real constructions. Experimental results designated that BL and BC performed better than BR, in which the temperature across the brick was shaved by up to 5 °C with a 30–60 min time lag. Generally, BL exhibited slightly better thermal performance than BC; nonetheless, it showed a sharp decline in compression strength. Conclusively, the brick-based PCM layer was thermally better than that-based PCM capsules, but the latter has superior mechanical properties.

The impact of rising temperatures on the prevalence of coral diseases and its predictability: A global meta-analysis.

Coral reefs are under threat from disease as climate change alters environmental conditions. Rising temperatures exacerbate coral disease, but this relationship is likely complex as other factors also influence coral disease prevalence. To better understand this relationship, we meta-analytically examined 108 studies for changes in global coral disease over time alongside temperature, expressed using average summer sea surface temperature (SST) and cumulative heat stress as weekly sea surface temperature anomalies (WSSTAs). We found that both rising average summer SST and WSSTA were associated with global increases in the mean and variability in coral disease prevalence. Global coral disease prevalence tripled, reaching 9.92% in the 25 years examined, and the effect of 'year' became more stable (i.e. prevalence has lower variance over time), contrasting the effects of the two temperature stressors. Regional patterns diverged over time and differed in response to average summer SST. Our model predicted that, under the same trajectory, 76.8% of corals would be diseased globally by 2100, even assuming moderate average summer SST and WSSTA. These results highlight the need for urgent action to mitigate coral disease. Mitigating the impact of rising ocean temperatures on coral disease is a complex challenge requiring global discussion and further study.