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PurposePerspiration and heat are produced by the body and must be eliminated to maintain a stable body temperature. Sweat, heat and air must pass through the fabric to be comfortable. The cloth absorbs sweat and then releases it, allowing the body to chill down. By capillary action, moisture is driven away from fabric pores or sucked out of yarns. Convectional air movement improves sweat drainage, which may aid in body temperature reduction. Clothing reduces the skin's ability to transport heat and moisture to the outside. Excessive moisture makes clothing stick to the skin, whereas excessive heat induces heat stress, making the user uncomfortable. Wet heat loss is significantly more difficult to understand than dry heat loss. The purpose of this study is to provided a good compilation of complete information on wet thermal comfort of textile and technological elements to be consider while constructing protective apparel.Design/methodology/approachThis paper aims to critically review studies on the thermal comfort of textiles in wet conditions and assess the results to guide future research.FindingsSeveral recent studies focused on wet textiles' impact on comfort. Moisture reduces the fabric's thermal insulation value while also altering its moisture characteristics. Moisture and heat conductivity were linked. Sweat and other factors impact fabric comfort. So, while evaluating a fabric's comfort, consider both external and inside moisture.Originality/valueThe systematic literature review in this research focuses on wet thermal comfort and technological elements to consider while constructing protective apparel.

Photovoltaic/thermal (PV/T) utilization has been regarded as a promising technique to efficiently harvest solar energy, but its thermal efficiency highly degrades in cold seasons because of remarkable heat loss. Although various methods, such as using air or vacuum gap, have been used to reduce heat loss of the PV/T, heat radiative loss still exists. In addition, unlike selective solar absorbers, the current PV/T absorber behaves like an infrared blackbody, showing great radiative heat loss. To overcome this drawback, a novel aerogel PV/T (referred to as “A-PV/T” hereinafter) collector based on solar transparent and thermally insulated silica aerogel is proposed, which can reduce the heat loss from both the non-radiative and radiative heat transfer modes. Experimental testing demonstrates that the thermal efficiency improvement of 25.1%-348% can be achieved for PV/T within the collecting temperature range of 35–70 °C when silica aerogel is introduced, indicating a significant efficiency enhancement. Compared with traditional PV/T (referred to as “T-PV/T” hereinafter) collector, the stagnation temperatures of the A-PV/T collector are 96.7 °C and 103.1 °C in outdoor and indoor environments, which are 27.4 °C and 25.8 °C greater, respectively, indicating a heat loss suppression of the aerogel. Moreover, simulation reveals that useful heat can hardly be provided by the T-PV/T collector in cold seasons, but the A-PV/T still exists a high solar thermal performance, showing good seasonal and regional applicability.

On the plateau, symmetrical (WDS) and asymmetrical (WLS) dressing habits have been developed to adapt to the extreme climate of the plateau, which is characterized by large temperature variations. Few studies have investigated the impact of these dressing styles on the heat loss and thermal comfort of the Xizang people. To better characterize these impacts, models representing local heat loss of human are developed, and human heat loss experiments are conducted on the plateau. The results showed that the WLS increased the total heat loss of the participants by a range between 7.2 % and 25.7 % compared to the WDS; however, WLS narrowed the range of localized heat loss and reset the distribution of heat loss intensity. Adopting the WLS, the localized convection and radiation heat loss reported in the right sleeve was higher than that of the WDS by a range of 3.1 to 12.5 W/m 2 and 5.2 to 22.5 W/m 2 , respectively. Also, the results of thermal neutral temperature of the participants increased by 2 °C when the WLS was utilized. Focusing on the distribution of heat loss to achieve localized insulation through clothing thermal regulation is an effective strategy to achieve human thermal comfort and energy savings.

To maintain constant body temperature (Tb) over a wide range of ambient temperatures (Ta) endothermic animals require large amounts of energy and water. In hot environments, the main threat to endothermic homeotherms is insufficient water to supply that necessary for thermoregulation. We investigated flexible adjustment of traits related to thermoregulation and water conservation during acclimation to hot conditions or restricted water availability, or both, in the zebra finch, Taeniopygia guttata a small arid-zone passerine. Using indirect calorimetry, we measured changes in whole animal metabolic rate (MR), evaporative heat loss (EHL) and Tb before and after acclimation to 23 or 40 °C, with different availability of water. Additionally, we quantified changes in partitioning of EHL into respiratory and cutaneous avenues in birds exposed to 25 and 40 °C. In response to heat and water restriction zebra finches decreased MR, which together with unchanged EHL resulted in increased efficiency of evaporative heat loss. This facilitated more precise Tb regulation in heat-acclimated birds. Acclimation temperature and water availability had no effect on the partitioning of EHL into cutaneous or respiratory avenues. At 25 °C, cutaneous EHL accounted for ~ 60% of total EHL, while at 40 °C, its contribution decreased to ~ 20%. Consistent among-individual differences in MR and EHL suggest that these traits, provided that they are heritable, may be a subject to natural selection. We conclude that phenotypic flexibility in metabolic heat production associated with acclimation to hot, water-scarce conditions is crucial in response to changing environmental conditions, especially in the face of current and predicted climate change.

The efficiency of the parabolic dish concentrator system is primarily affected by the geometrical parameters of the receiver. To understand these effects, optical and thermal analysis of a cylindrical-hemispherical cavity receiver is carried out in this paper. The optical efficiency of the receiver is evaluated for varying receiver height ( h ) from 0.135 to 0.165 m and coil tube diameter ( d t ) from 0.009 to 0.012 m using the Monte Carlo Ray Tracing Method, and it is found that the optical efficiency is achieved to be 92.87% for the receiver having tube diameter of 0.012 m with height of 0.145 m. Thermal analysis of the receiver is also carried out to estimate the heat loss in both natural and forced convection modes using numerical modeling. The heat losses are analyzed for varying factors like receiver orientation (γ = 0º to 90º), wind velocity ( V  = 0 to 6 m s −1 ) and receiver temperature ( T  = 600 and 700 K) with head-on wind and back-on wind directions. The results illustrate that the heat loss from the receiver is high at γ  = 60º for head-on wind direction; and for back-on wind direction, this is high at γ  = 90º. On the other hand, the minimum heat loss is observed at γ  = 30º for both directions of wind. Artificial Neural Network is also applied to estimate the convective heat loss from the receiver. Error matrices like average percentage error (APE), maximum correlation coefficient (R), and root mean square error (RMSE) are used to evaluate the model performance considering input variables like receiver aperture diameter ( D ), receiver orientation ( γ ), surface temperature of the receiver ( T s ), and wind velocity ( V ). Also, the predicted values of ANN have been compared with the results obtained from numerical analysis to evaluate the error percentage.

In this paper, the efficient amounts of radiation received by a flat‐plate collector and top heat loss coefficient along with affecting parameters are investigated using measured data in different climates of Iran. Coded program in MATLAB software is then distributed to calculate the optimum tilt angle for extracting the highest solar radiation in different months of the year for five cities of Iran with different geographic latitudes. An optimal annual slope is obtained for maximum utilization and for conditions where the collector can only be adjusted at an angle during the year. Using an interpolation, an equation has been derived for obtaining the optimal tilt angle of collector for areas with latitude between 27° and 37°. Inasmuch as the top heat loss coefficient is required for evaluating the thermal performance of solar collectors, the value for different temperatures is obtained at ambient temperature up to 200°C for the absorber plate. Effects of key parameters such as collector slope, number of covers, wind speed, emittance coefficient of adsorption plate, and cover spacing on top heat loss coefficient are investigated. In the end, the particle swarm optimization (PSO) method is employed to minimize the top heat loss coefficient. The minimum amount of top heat loss coefficient is obtained with the amount of 0.99 W/m2K. The efficient amounts of radiation received by a flat‐plate collector and top heat loss coefficient along with affecting parameters are investigated. Particle swarm optimization (PSO) method is employed to minimize the top heat loss coefficient.

The efficiency of the parabolic dish system is significantly impacted by the thermal energy lost from the receiver. Well-established correlations can be used to determine the energy’s conduction and radiation modes. However, due to the complex flow behavior near the cavity receiver, estimating the loss of convective heat is difficult. Surprisingly, the majority of studies has solely examined forced convection from the cavity and has not considered the impact of the dish structure. The presence of the dish structure may alter the local wind patterns near the cavity, which may also affect heat loss. Given the importance of an improved thermal model, the behavior of the wind flow must thus be investigated by adding the dish structure. The numerical results obtained in this work confirm that the dish has a significant impact on the flow in the cavity region. Under normal operating conditions, the cavity receiver is protected from the free stream flow by the dish architecture. Because the local flow velocity is relatively low near the receiver, there is a noticeable reduction in heat loss from the device.

A solar pond technology employs a layer of salinity gradient to prevent heat loss due to convection from the lower convective zone. Thus, the energy received from solar radiation is stored in a lower convective zone. The thickness of various zones significantly affects the behaviour of solar pond temperature. In this present study, a transient numerical investigation is conducted to evaluate the impact of depths of different zones on the performance characteristics of solar pond. The variation in maximum temperature and maturation period under the influence of non-convective zone and lower convective zone thickness is discussed. The energy obtained from a solar pond significantly depends on various losses associated with the zones. Thus, an assessment of conduction and ground heat loss is presented for the variation in thickness of zones. An attempt is also made to study the effect of thickness of zones on the temperature of the lower convective zone. It is found that the configuration of a smaller thickness of LCZ and a higher thickness of NCZ yields maximum LCZ temperature.

The article presents the results of analysis of thermal operation and hearth lining melting of blast furnaces of various designs on the basis of information from the system of monitoring of thermal operation and hearth lining melting – mathematical model “Hearth” developed in Iron and Steel Institute NAS of Ukraine (ISI NASU). Realization of continuous monitoring of the hearth melting in blast furnaces made it possible to estimate the effect of using “ceramic cup” in terms of the value of heat losses of the hearth and coke consumption for their compensation. It is established that the value of specific heat loss per unit volume of blast furnace in blast furnaces with a “ceramic cup” ~ 0,4-0,7 kW/m3, in blast furnaces without it ~0,9-1,1 kW/m3. Ceramic cup gives savings of about 1 kg/t-HM of coke.

Seventy percent of global greenhouse gas (GHG) emissions originate from urban areas, with urban heat loss contributing significantly to energy consumption (UNEP, 2020). Digital twins offer a potential solution and insight into the problem and its causes. This is a study started as an undergraduate Engineering Capstone Project with a collaborative effort between the University of New Brunswick and the National Research Council of Canada to develop a workflow to aid thermal efficiency modeling using Digital twins. This project uses the University of New Brunswick (UNB) Fredericton campus as a case study to capture UAV, nadir perspective LiDAR, Panchromatic imagery and long wave infrared (LWIR) thermal imagery. The workflow includes 4 major steps following the preprocessing: (1) creating point clouds from the LiDAR and Panchromatic sources, (2) merging point clouds using grid-based segmentation and iterative closest point algorithm (ICP), (3) classifying the point cloud using Point CNN networks aided by manual refinement, and (4) overlaying thermal data. The resulting digital twin achieved a high level of spatial alignment accuracy, with 95% of points falling on building surfaces falling within an 11 cm tolerance as assessed by quadric cloud-to-cloud distance. Semantic classification performed using Point CNN and faster R-CNN object detection identified façade features such as windows and doors with a precision of 91.8% and an F1 score of 83%. Thermal data was successfully integrated and converted to approximate temperature values, enabling further analysis of surface heat behavior and laying the groundwork for future energy modeling applications. This case study demonstrates a scalable framework for high-detail drone based digital twin development with practical relevance to urban thermal efficiency analysis.