Maintaining human thermal comfort in the cold outdoors is crucial for diverse outdoor activities, e.g., sports and recreation, healthcare, and special occupations. To date, advanced clothes are ...employed to collect solar energy as a heat source to stand cold climates, while their dull dark photothermal coating may hinder pragmatism in outdoor environments and visual sense considering fashion. Herein, tailor‐made white webs with strong photothermal effect are proposed. With the embedding of cesium–tungsten bronze (CsxWO3) nanoparticles (NPs) as additive inside nylon nanofibers, these webs are capable of drawing both near‐infrared (NIR) and ultraviolet (UV) light in sunlight for heating. Their exceptional photothermal conversion capability enables 2.5–10.5 °C greater warmth than that of a commercial sweatshirt of six times greater thickness under different climates. Remarkably, this smart fabric can increase its photothermal conversion efficiency in a wet state. It is optimal for fast sweat or water evaporation at human comfort temperature (38.5 °C) under sunlight, and its role in thermoregulation is equally important to avoid excess heat loss in wilderness survival. Obviously, this smart web with considerable merits of shape retention, softness, safety, breathability, washability, and on‐demand coloration provides a revolutionary solution to realize energy‐saving outdoor thermoregulation and simultaneously satisfy the needs of fashion and aesthetics.
A white composite fabric with an exceptional photo‐to‐thermal conversion capability that outperforms ordinary black photothermal fabric is developed. Collective characteristics of shape retention, softness, breathability, light weight, fast‐drying, durability, and tailorability into diverse appearances are integrated into this novel fabric, which promises to satisfy the needs of future advanced garment manufacturing, thermoregulation, and aesthetics.
Iontophoretic transdermal administration of NG-nitro-l-arginine methyl ester hydrochloride l-NAME, a nitric oxide synthase (NOS) inhibitor has been used as a non-invasive evaluation of NOS-dependent ...mechanisms in human skin. However, the availability has yet to be investigated in sweating research. Prior observations using invasive techniques (e.g., intradermal microdialysis technique) to administer l-NAME have implicated that NOS reduces sweating induced by heat stress but rarely influences the response induced by the administration of cholinergic muscarinic receptor agonists. Therefore, we investigated whether the transdermal iontophoretic administration of l-NAME modulates sweating similar to those prior observations. Twenty young healthy adults (10 males, 10 females) participated in two experimental protocols on separate days. Before each protocol, saline (control) and 1% l-NAME were bilaterally administered to the forearm skin via transdermal iontophoresis. In protocol 1, 0.001% and 1% pilocarpine were iontophoretically administered at l-NAME-treated and untreated sites. In protocol 2, passive heating was applied by immersing the lower limbs in hot water (43 °C) until the rectal temperature increased by 0.8 °C above baseline. The sweat rate was continuously measured throughout both protocols. Pilocarpine-induced sweat rate was not significantly different between the control and l-NAME-treated sites in both pilocarpine concentrations (P ≥ 0.316 for the treatment effect and interaction of treatment and pilocarpine concentration). The sweat rate during passive heating was attenuated at the l-NAME-treated site relative to the control (treatment effect, P = 0.020). Notably, these observations are consistent with prior sweating studies administrating l-NAME into human skin using intradermal microdialysis techniques. Based on the similarity of our results with already known observations, we conclude that transdermal iontophoresis of l-NAME is a valid non-invasive technique for the investigation of the mechanisms of sweating related to NOS during heat stress.
•A non-invasive method to assess nitric oxide-dependent sweating is required.•Efficacy of transdermal l-NAME iontophoresis on sweating was assessed.•l-NAME iontophoresis could replicate sweat responses consistent with prior studies.•l-NAME iontophoresis is likely a valid method available in sweating research.
•Innovative buried pipe design significantly boosts performance; reconfigured garage manifold enhances heat transfer by 37 %.•Design optimization focusing on component synergy elevates overall system ...performance.•Horizontal manifold heat transfer is most affected by surface temperature, followed by water supply section burial depth, pipe material, flow rate and cover material.•For summer cooling, the ideal horizontal manifold configuration across four scenarios (underground garage, lawn, plaza, and asphalt) is a burial depth of 1.3 m, coupled with tailored materials and flow rates.
This study investigates the importance of improving the heat transfer efficiency of buried pipe systems by optimising the horizontal manifold layout in ground source heat pump systems under summer conditions. Based on the similarity theory, we developed a novel horizontal manifold layout method on a sandbox experimental bench. The heat loss of horizontal manifold in different scenarios (underground garage, lawn, square and road) was investigated by orthogonal tests. The study identifies the optimal layout of the horizontal manifold for different scenarios, with a special focus on how the new layout can effectively reduce the outlet temperature in a 20 ℃ underground garage environment. The new solution improves the overall heat transfer performance of the system by 37 % compared to the traditional horizontal manifold layout. The study highlights that even if individual component efficiencies are not optimal, a sensible system configuration can still optimise overall performance, and synergies between components need to be considered. Extreme variance analysis reveals the influence of five key factors on the heat transfer efficiency of the horizontal manifold, with surface temperature having the most significant effect. This study provides an integrated optimisation approach for ground source heat pump systems, which is particularly suitable for diverse application scenarios. These findings not only improve the performance of ground source heat pump systems, but also provide valuable guidance for practical engineering design, offering new perspectives on the application and optimisation of ground source heat pump systems.
Paddy drying is a spontaneous dehydration process following the principles of high product quality, high drying efficiency, low energy consumption, and environmental protection. However, its complex ...properties hinder the development of optimal control during drying. In this study, the real-time paddy drying state of a paddy multistage counter-flow dryer is simulated utilising numerical simulation technology. Results indicate the simulation results agreed well with the experimental data with mean relative deviation of less than 15%. Moreover, the steady and transient characteristics of present dryer are analysed under multiple disturbances. In addition, the effects of ambient and ventilation parameters on productivity, specific energy consumption, heat loss, and exergy loss characteristics are investigated in detail. Based on the simulation and analysis, a uniform design experiment is performed to determine the optimal ventilation parameters of paddy with initial moisture content of 0.238 g water g−1 wet matter when ambient temperature and relative humidity are 20 °C and 50%, respectively. Drying air temperatures of 60 °C and 40 °C, and flow velocity of 1600 m h−1 and 1150 m h−1, respectively, in the high- and low-temperature drying stages are found to be the optimal ventilation parameters.
•Captured the steady and transient characteristics of paddy multistage counter-flow dryer.•Analysed the energetic performance under different ambient and ventilation parameters.•Proposed an optimal ventilation strategy considering productivity and energy consumption.
While surface microstructures of butterfly wings have been extensively studied for their structural coloration or optical properties within the visible spectrum, their properties in infrared ...wavelengths with potential ties to thermoregulation are relatively unknown. The midinfrared wavelengths of 7.5 to 14 μm are particularly important for radiative heat transfer in the ambient environment, because of the overlap with the atmospheric transmission window. For instance, a high midinfrared emissivity can facilitate surface cooling, whereas a low midinfrared emissivity can minimize heat loss to surroundings. Here we find that the midinfrared emissivity of butterfly wings from warmer climates such as Archaeoprepona demophoon (Oaxaca, Mexico) and Heliconius sara (Pichincha, Ecuador) is up to 2 times higher than that of butterfly wings from cooler climates such as Celastrina echo (Colorado) and Limenitis arthemis (Florida), using Fourier-transform infrared (FTIR) spectroscopy and infrared thermography. Our optical computations using a unit cell approach reproduce the spectroscopy data and explain how periodic microstructures play a critical role in the midinfrared. The emissivity spectrum governs the temperature of butterfly wings, and we demonstrate that C. echo wings heat up to 8 °C more than A. demophoon wings under the same sunlight in the clear sky of Irvine, CA. Furthermore, our thermal computations show that butterfly wings in their respective habitats can maintain a moderate temperature range through a balance of solar absorption and infrared emission. These findings suggest that the surface microstructures of butterfly wings potentially contribute to thermoregulation and provide an insight into butterflies' survival.
The dynamic development of built-up areas observed in the last few decades resulted in strong environmental transformations, especially in terms of climate phenomena. One of the factors which ...significantly affects the climate and bioclimate of urban areas is wind. Wind can cause discomfort to pedestrians or heat loss in buildings, if the wind speed around buildings is too high. The paper presents two examples of research conducted by the author, related to the issues of wind flow in built-up areas, based on the numerical simulations. The numerical simulations become an increasingly frequently used tool to determine the wind climate. Simulation results provide designers with important information on the influence of the buildings and their layout on the local changes in airflow. They allow testing of alternative solutions and effectiveness of various remedial measures.
•Embodied and operational energy and carbon emissions of a passive building are evaluated.•Embodied energy and carbon emissions of passive building is 37.6% and 16.2% higher than conventional ...building, respectively.•Total life cycle energy requirement and carbon emissions of passive building is 17.4% and 22.7% lower than conventional building, respectively.
Passive building is generally regarded as the energy-efficient building to reduce the primary energy consumption and related carbon emissions. It is suggested that the most effective way to minimize the space heating energy demand is to decrease heat loss by enhancing the thermal and airtightness performance of building envelope.
And it is suited to the buildings in cold climates for decreasing space heating energy consumption which dominates the operational energy. However, the appropriate design strategy of building depends on climates. In HSCW (hot summer and cold winter) zone in China, for instance, the space heating is just one issue of energy demand in operational stage, the energy use for cooling and dehumidification in summer also accounts for a considerable proportion in operational stage of buildings. The effect of decreasing the cooling energy demand will become smaller as thickness of insulation layer increases, the unfavorable highly insulated envelope may even cause the overheating risk in summer. In addition, embodied energy and carbon emissions will markedly increase as more materials are consumed in passive buildings. Therefore, in order to get an appropriate design strategy of passive buildings in HSCW zone in China, further research on energy consumption and carbon emissions of embodied and operational stage is needed. In this case, detailed life cycle analysis of embodied and operational energy use and carbon emissions of a passive building is given and then compared with a conventional building in the same unique climate zone. The embodied energy consumption and carbon emissions of the passive building is 7.31 GJ/m2 and carbon 0.98 t CO2 eq/m2, 37.6% and 16.2% higher than that of conventional building respectively. Due to the benefits on the operational stage, the total life cycle energy requirement and carbon emissions of passive building is 17.4% and 22.7% lower than that of conventional building, respectively. Towards a zero energy and impact building, the design of passive cooling, high efficiency cooling equipment and renewable energy to reduce remaining energy demand should be paid more attention in further passive buildings in this climate.
•Propagation of one-dimensional planar flames laden with fuel droplets is investigated.•Correlations describing gaseous flame properties and droplet evaporation are derived.•Flames are enhanced under ...fuel-lean conditions but weakened under fuel-rich conditions.•Flame bifurcation occurs with high droplet mass loading under fuel-rich conditions.•Speed of fuel-lean heterogeneous flames with medium droplets increases with lewis number.
Propagation of one-dimensional planar flames laden with fuel droplets is theoretically investigated in this work. Localized homogeneous and heterogeneous flames are considered, characterized by different relative locations of dispersed droplets and propagating flame front. With the assumption of large activation energy for the chemical reaction, correlations describing flame propagation speed, flame temperature, evaporation onset front and completion front are derived. The influences of droplet and fuel properties on propagation of fuel-droplet-laden planar flames are studied. The results indicate that the flames are enhanced under fuel-lean conditions but weakened under fuel-rich conditions. Both effects are intensified with increased droplet mass loading. Fuel vapor and temperature gradient are observed in the post-flame evaporation zone of heterogeneous flames. Evaporation completion front location is considerably affected by the droplet diameter, but the evaporation onset front varies little with droplet properties. Flame bifurcation occurs with high droplet mass loading under fuel-rich mixture, leading to multiplicity of flame propagation speed as well as droplet evaporation onset and completion fronts. Sprayed fuels with larger latent heat of vaporization would weaken the flame enhancement effect under fuel-lean conditions, due to larger evaporation heat loss. Moreover, for homogeneous flames, evaporative heat loss only occurs in the pre-flame zone. However, for heterogeneous flames, heat loss from the post-flame evaporation zone becomes dominant for relatively large droplets. Besides, for fuel-lean mixtures laden with medium-sized fuel droplets, the propagation speed of heterogeneous flames increases with Lewis number, due to the enhanced fuel vapor diffusion in the post-flame zone.
One of the structural elements used in the construction of insulating glass units (IGUs) are tight gaps filled with gas, the purpose of which is to improve the thermal properties of glazing in ...buildings. Natural changes in weather parameters: atmospheric pressure, temperature, and wind influence the gas pressure changes in the gaps and, consequently, the resultant loads and deflections of the component glass panes of a unit. In low temperature conditions and when the atmospheric pressure increases, the component glass panes may have a concave form of deflection, so that the thickness of the gaps in such loaded glazing may be less than its nominal thickness. The paper analyses the effect of reducing this thickness in winter conditions on the design heat loss through insulating glass units. For this purpose, deflections of glass in sample units were determined and on this basis the thickness of the gaps under operating conditions was estimated. Next, the thermal transmittance and density of heat-flow rate determined for gaps of nominal thickness and of thickness reduced under load were compared. It was shown that taking into account the influence of climatic loads may, under certain conditions, result in an increase in the calculated heat loss through IGUs. This happens when the gaps do not transfer heat by convection, i.e., in a linear range of changes in thermal transmittance. For example, for currently manufactured triple-glazed IGUs in conditions of "mild winter", the calculated heat losses can increase to 5%, and for double-glazed IGUs with 10-14 mm gaps this ratio is about 4.6%. In other cases-e.g., large thickness of the gaps in a unit, large reduction in outside temperature-convention appears in the gaps. Then reducing the thickness of the gaps does not worsen the thermal insulation of the glazing. This effect should be taken into account when designing IGUs. It was also found that the wind load does not significantly affect the thickness of the gaps.
Nowadays, with the advancement of construction technology, saving energy use of the building has been considered as one of the fields of environmental sustainability. The use of green cover and ...plants on the buildings is a suitable passive method that leads to the replace reduced urban green spaces and reduce the problems caused by the effect of the urban heat island (UHI) and improve the energy performance of buildings by reducing the indoor temperature, regulating humidity and creating thermal insulation. The objective of this study was to evaluate the reduction of energy consumption through the green walls of an educational building in Gorgan (Csa climate). For this purpose, first, a building designed on the university site, and the effects of two methods of constructing green walls by using three different plant species were simulated. For comparison, thermal data of a building with a direct green facade in the same climate was measured as an experimental sample, and the results were used in the simulation. The effects of using two methods of a green wall with three different plant species (Sedum, Parthenocissus tricuspidata, Hedera helix) were simulated, which Sedum has had better results than other species. The final results showed that the latent heat of the building is increased by green walls and less significant heat is generated in the environment than buildings without green cover. Also, in buildings with living green walls, compared to buildings with direct green facades, the thermal transmittance of the wall is reduced due to more material layers. The results show that some types of green walls reduce heat loss, and finally the total energy use of the building. The green wall has a more efficient effect on the buildings with a simple form and the limited number of interior spaces. In general, depending on the variables of each building, the use of green walls with plant species is different. It is better for a building before design, to determine the most appropriate method of constructing a green wall and plant species to reduce the energy usage according to project factors and climate type of the region.
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