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In this work, we investigate the influence of ZnO nanoparticles on the performance of paper-based humidity sensors. The sensors were developed on standard, commercial printing paper with laser-patterned gold interdigitated electrodes (IDE) and ZnO nanoparticles spin-coated by various sol-gels. Blank devices were used as reference sensors in an effort to elucidate the role of ZnO and the dependence of the device performance on the concentration of the sol-gels and the number of spin-coated layers. Resistive measurements were conducted at room temperature to evaluate the devices’ response on known relative humidity levels. Relatively fast rise and response times were observed even at room temperature, while all devices tested did not require refreshing procedures. The deposition of ZnO was found to affect the sensor response, resulting in reduced sensor signal, due to the blocking of water diffusion in the porous paper material. [ABSTRACT FROM AUTHOR]

This paper deals with the study of volatile compounds present in a set of three paper and board (P&B) samples of different composition, surface treatment, grammage and thickness. The volatile compounds released by the packaging material (P&B) can be trapped on the food and may then affect the safety and health of consumers. To evaluate if the recycled P&B could be used as food packaging material, adsorption studies have been performed with a selection of chemical substances. The adsorption isotherms are provided. Partition coefficients between paper and air have been calculated for a series of volatile compounds used as model compounds to represent different families of contaminants commonly present in P&B. Values from 4 to 3243 were obtained at different temperatures. The analysis of volatile compounds have been carried out by automatic headspace coupled on-line with GC/MS in SIM mode. The results obtained are shown and discussed. [Copyright &y& Elsevier]

Lactic acid promises to be an important commodity chemical in the future as a monomer for the production of biodegradable polylactic acid. With the increase of the lactic acid demand, the need to explore alternative feedstock sources and purification processes that are inexpensive and efficient is becoming more important. This paper first reports the purification results of lactic acid from the fermentation broth with paper sludge as a cellulosic feedstock using weak anion exchanger Amberlite IRA-92. Some factors such as flow rate, sample volume loaded, pH, and column were systematically examined to improve the purity, yield and productivity in lactic acid purification. Adsorption isotherm of standard lactic acid and lactic acid in the fermentation broth by anion exchanger IRA-92 were also investigated. Results indicate that in purification process the increase of pH of the fermentation broth ranging from 5.0 to 6.0 can significantly enhance the recovery yield, purity and productivity. The decrease of flow rate and sample volume loaded can also improve the recovery yield and purity but apparently reduce the productivity. In addition, the scale-up of purification process in laboratory size has little influence on the recovery yield and purity. After optimization, the yield, purity and productivity are found to be about 82.6%, 96.2% and 1.16 g LA/(g-resin day), respectively. [Copyright &y& Elsevier]

Transformation plays a significant role in solving hydrological problems. In response to the comment on Singh and Das (2015) by Deng et al. (2015) regarding the transformation, boundary conditions and subsequent analytical solution of advection dispersion equation in semi-infinite heterogeneous porous media, it is argued that the transformation used by Singh and Das (2015) for finding the analytical solution is correct and mathematically valid. Also, the different expression of f (mt) used to obtain the solution are explained with their physical relevance in the field. [ABSTRACT FROM AUTHOR]

Ultrafast high-temperature heating methods based on the Joule heating of carbon heaters can dramatically shorten the time required for material synthesis/sintering. However, commonly used porous carbon heaters cannot provide stable high temperatures in air, limiting their applicability to the processing of atmosphere-sensitive materials. In this study, we present a novel configuration for ultrafast high-temperature heating in air using commercial graphite paper. This configuration enables stable high temperatures of ~1330–2230 °C in air, on the time-scale of minutes, and ultrafast heating rates, reaching ~104 oC/min. We describe the mechanism behind the excellent performance of our proposed configuration, and further demonstrate its flexibility and controllability by considering ultrafast high-temperature sintering of ZnO ceramics with tunable microstructures using different heating profiles. Our configuration provides a complementary approach to simplifying the ultrafast high-temperature heating process, reducing costs, and meeting the requirements of synthesis/sintering in air. [ABSTRACT FROM AUTHOR]

Abstract: Mold deterioration of historical library materials in archives and libraries is a frequent and complex phenomenon that may have important economic and cultural consequences. Compactus shelving is one of the systems utilised for the conservation of library materials, because it allows for a more efficient use of space and protection against dust deposition. However, in the last ten years there have been many reports on single species mould infections within Compactus shelves in spite of conventional control of environmental temperature and humidity to recommended standards. Contamination was commonly characterized by white spots of mycelium, measuring 0.5–1.0 cm in diameter and observed on volume binding, especially those of leather, parchment or textile. Until now, the identification of the causal agent at species level has not been reported since attempts to grow it on media for subsequent identification were unsuccessful. Using a range of sampling techniques, including adhesive tape and nitrocellulose membrane, and a combination of conventional culturing methods, direct microscopic observations and molecular methods, we have for the first time identified to species level the fungus causing infections inside Compactus shelves. [Copyright &y& Elsevier]

Defining the required trackability level of the target condition for the testing facility reconditioning unit represents an unresolved challenge in improving the reproducibility of load-based tests and corresponding performance rating standards development. To enhance the reproducibility of such testing methodology, this paper presents and discusses a new feed-forward compensation technique based on the development of a transfer function model for the delay and offset characteristics of the psychrometric room's air temperature and humidity modulations with reference to the target signal from the room emulator. It is demonstrated that the proposed methodology enables offset and delay reduction in the trackability of the return air condition within 60 s at different testing conditions, enhances the reproducibility of the test results to limit performance deviations to within 2 %, and achieves closely matched controlled parameter modulations during load-based tests. [ABSTRACT FROM AUTHOR]

• The operating performances of a CASHP in LTS and HTS were tested. • Compressor speed plays opposite roles in LTS and HTS to affect the pressure ratio and COP. • Changes of the compressor speed in LTS failed to improve the COP of a CASHP unit. • Empirical models predicting COP in LTS and HTS were established. Previous studies on cascade air source heat pumps (CASHPs) mainly focused on overall performances, while impacts of the low temperature stage (LTS) and high temperature stage (HTS) on overall performances were paid less attention to. Therefore, operating performances of a CASHP in LTS and HTS were investigated in this paper, to provide a solution for the optimization of the CASHP. A CASHP unit with a variable speed compressor in LTS and a constant speed compressor in HTS was adopted, and its operating performances were investigated under 26 cases. Results showed that the pressure ratio and COP in LTS and HTS were affected differently by the compressor speed. Specifically, as the speed of the compressor in LTS increased from 30 rps to 90 rps, P rL increased by 151 % ∼ 178 %, and P rH reduced by 38 % ∼ 54 %. Meanwhile, COP in LTS reduced by 21 % ∼ 52 %, but the COP in HTS rose by 54 % ∼ 96 %. Besides, it was found that adjustments of the compressor speed in LTS could improve heating performances of the CASHP. However, when the ambient air temperature and the supply water temperature were consistent, COP changes of the CASHP were limited, only by 0.3 % ∼ 9 %. Furthermore, empirical models of the COP in LTS and HTS were established to predict the COP of the CASHP on different operating conditions. Results of this study were helpful in promoting the configurations and operation control optimization of CASHPs. [ABSTRACT FROM AUTHOR]

Spiral blast freezing is a common unit operation used in food processing facilities for rapidly freezing a variety of foodstuffs. The purpose of a blast freezer is to generate high velocity, low temperature air flow over food products being conveyed within refrigerated enclosures to accomplish the freezing process. However, air flow patterns observed within field operating blast freezers are often suboptimal, resulting in diminished system performance. This paper applies a Monte Carlo simulation technique to a food product freezing simulation in order to identify velocity profiles that optimize the freezing process. A one-dimensional food product model is used to evaluate the interplay between the time variation in the magnitude of the air velocity over food products conveyed through the freezing system and the resulting dwell time needed to achieve a target product core temperature at the blast freezer exit. Temporal heat transfer coefficients derived from field measurements made in a newly installed spiral blast freezer serve as a basis to calibrate the one-dimensional product model. The results of the Monte Carlo analysis show freezing system performance is improved when high and stable air velocities over the product are achieved early in the freezing process dwell time. Air flow patterns within a freezing system that result in high air velocity later in the freezing process dwell time are suboptimal. Field-measured data on a newly installed spiral blast freezer showed this suboptimal air flow pattern and the use of baffling within the spiral enables improved airflow leading to an estimated 10 % increase in production throughput. [ABSTRACT FROM AUTHOR]

This paper compares the performance of a vertical-finned microchannel heat exchanger (VMHX) and a 2-row fin-tube heat exchanger (FTHX) under wet and frosting conditions. The VMHX features vertically oriented fins with an extension at the windward side and parallel microchannel tubes, allowing for efficient water drainage and better performance than conventional microchannel heat exchangers with parallel serpentine fins. However, the performance of the VMHX has not been sufficiently compared to that of FTHX. After conducting experiments under specific operating conditions, the VMHX exhibits better water drainage performance than the FTHX at higher inlet air velocities, higher maximum heat flow, and time-integrating heat flow under certain operating conditions. Although the heating time is relatively shorter than the 2-row FTHX, these results suggest that the VMHX may be a more suitable option for applications requiring efficient water drainage and heat transfer. Additionally, the operating conditions significantly affect the heat exchanger's performance. The performance of VMHX is analyzed under different inlet air velocities, inlet air temperatures, and evaporation temperatures. The results indicate that frost itself had no effect on the heat exchanger performance and that the decrease of the inlet air flow rate was the main factor that decreased the heat exchanger performance. Overall, the results of this study provide valuable insights into the performance of VMHX and FTHX under wet and frosting conditions and the impact of various operating parameters on VMHX performance. These findings can inform the development of more efficient and reliable heat exchangers for various applications. [ABSTRACT FROM AUTHOR]

Thermal stratification widely exists in large reservoirs, causing significant inflow-outflow temperature difference (IOTD), which goes against the downstream ecology. Reservoir optimal operation has recently been conducted to regulate the outflow temperature, while its effects for cascade reservoirs urgently needed to be illuminated. Taking the typical Xiluodu-Xiangjiaba cascade reservoirs (XXCR) as study case, this paper had built a multi-objective optimal operation model combing the non-dominated sorting genetic algorithm II (NSGA-II) and a hydrodynamic-temperature model, and the total power generation (TPG) and IOTD were simultaneously considered. The effects of different inflow discharge and global warming scenarios were analyzed. This paper showed the following: (1) The IOTD and TPG of XXCR showed a positively linear relationship with the water level of the superior Xiluodu Reservoir (XLD), instead of the inferior Xiangjiaba Reservoir (XJB). (2) The reservoir with larger water volume and depth (such as XLD) determined the thermal structure and hydropower generation in cascade reservoirs, compared with the inferior reservoir (such as XJB). (3) As the inflow discharge or air temperature increased, the slope between the IOTD and TPG in the Pareto front curve increased. The results of this paper could support the ecological operation for cascade reservoir to regulate the outflow temperature. [Display omitted] [ABSTRACT FROM AUTHOR]

One of the buzz words in current research depends for a weather forecast is the atmospheric temperature, and this value may change at any time. Predicting air temperature exactly is necessary since it is particularly important for various communities and events. In today's world of massive amounts of data and unforeseen data fluctuations, long-short term memory (LSTM), a sort of neural network method, is becoming more and more popular. The present work employed a sequence to sequence LSTM autoencoder to forecast Indian weather patterns. The prediction model was trained using historical data obtained from the Khordha district administration. The proposed method primarily emphasizes two phases of the procedure. The present study involves an examination of a proposed model, wherein a comparison is made between four distinct variants of LSTM techniques: vanilla LSTM, stacked LSTM, bidirectional LSTM, and convLSTM. The objective of this analysis is to predict temperature patterns. Additionally, this paper utilizes an LSTM autoencoder model to forecast the temperature for the subsequent two-year period in the Khordha district of Odisha, India. The experimental investigation demonstrates that the utilization of Stacking encoder-decoders with bidirectional LSTM cells leads to a notable enhancement in the accuracy of the model, resulting in maximum efficacy. A notably lower Mean Absolute Error (MAE) result suggests that the 9-layer stacked autoencoder model has superior performance in predicting both the minimum and maximum temperature. [ABSTRACT FROM AUTHOR]

• A direct evaporative cooler (DEC) integrates with split air conditioner (SAC). • DECSAC significantly improves C O P by 10.54 %−70.14 %. • Total cost rate (T C R) of DECSAC reduces by 5.07 %−25.36 %. • Water consumption for 1 kWh energy saving varies between 5.5 – 9.8 L. • Simple payback period lies between 1.21 to 2.99 years with maximum I R R being 59 %. As concerns regarding energy consumption and environmental impact continue to grow, the need for efficient and sustainable cooling technologies becomes increasingly significant. Among various alternatives, direct evaporative cooling (DEC) has emerged as a promising solution due to its energy-efficient operation and low environmental footprint. This paper aims to provide a comprehensive thermo-economic assessment of a 5.25 kW capacity split air conditioner (SAC) integrated with direct evaporative cooling, focusing on evaluating its performance, energy consumption, coefficient of performance (C O P) , and economic viability. A numerical model is developed to determine the reduction in the condenser inlet air temperature due to direct evaporative cooling. The ambient temperature (30–45 ⁰C), relative humidity (20–80 %), and evaporator temperature (3–12 ⁰C) are taken as the design variables. Box–Behnken design (BBD) technique of response surface methodology is applied for multi-objective optimization. The C O P , total cost rate (T C R) , and total exergy destruction ( E ˙ D , t ) are set as the objective functions. Cooling capacity, life period, operation time, interest rate, maintenance factor, and electricity cost are taken as constants. The thermoeconomic optimization evolved maximized C O P enhancement of 68.94 %, and reduction in TCR and E D , t by 26.12 % and 57.23 %, respectively. The water consumption to energy saving ratio varies from 5.5 to 9.8 L/kWh for different months of the cooling season. The thermoeconomic performance and sustainability of DECSAC is observed to significantly improve compared to conventional SAC specifically in hot-dry climates. The simple payback of the proposed system ranges between 1.21 to 2.99 years depending upon the operating conditions. [ABSTRACT FROM AUTHOR]

High absorption of PV benefits heat collection in the daytime, but the heat loss to the space/environment because of its high emissivity also should be noticed. Although there are many papers investigating PVT, few of them cover the night behavior and negative running during late afternoon. This paper supplements detailed studies on related content to draw people's attention to the night and late-afternoon operation that helps better strategy establishment and less heat loss. From experiments, the clouds help hinder the PV radiant heat exchange with space. Under clear night, the PV bottom temperature can be 6.88 °C lower than air temperature and the water tank's bottom temperature drops 2.8 °C. Because of the fluid viscosity, no apparent temperature stratification and flow occur in the PVT water pipe, causing even PV temperature. The higher the water temperature, the easier the negative running occurs during late afternoon, although the irradiation is still high at 521W/m2. Heat loss power and energy are −199W and 1791 KJ from 15:10 to 17:40. Based on different regressed linear correlations of different PVT systems, the effect of water temperature, irradiation, and ambient temperature on the negative performance is also comparatively studied. • Night behavior and negative running of PVT system are studied to avoid heat loss. • The clouds helps hinder the PV radiant heat exchange with the space. • PV bottom temperature can be 6.88 °C lower than ambient temperature. • Even the irradiation is still high at 521W/m2, negative running may still happen. • Negative operation is also comparatively studied based on different PVT and ambient. [ABSTRACT FROM AUTHOR]

• The outdoor air relative humidity also has an impact on the threshold temperature of frost accumulation. • Under certain conditions, higher efficiency of heat recovery may be safer in terms of frost risk. • The largest ' frost ' accumulation area is formed for the middle values of the return air relative humidity (in analyzed case RH 2 i =38.5 %). In this paper, a process of frost accumulation inside the non-hygroscopic rotary heat exchanger depending on operating conditions is investigated. The study was based on the results of the numerical simulations conducted in the original computer program. The analysis considers both the threshold conditions of frost accumulation and the conditions of frost layer growth. For this purpose, three indicators related to frost accumulation were distinguished: a frost accumulation limit temperature, a surface of the matrix covered with the accumulated frost layer, a maximum thickness of the accumulated frost layer. The analyzes assessed the influence of operating parameters on these indicators, focusing on the return air relative humidity. It was revealed that the highest values of this parameter cause the greater thickness of the frost layer. However, the largest ' frost ' accumulation area was created in the range of average return air relative humidity values – in the analyzed cases it was RH 2 i =38.5 %. The paper also includes a detailed analysis of the threshold temperature of frost accumulation. These limits of outdoor air temperature were determined for a wide range of operating parameters' values: both airstream relative humidity and nominal temperature effectiveness. Additionally, eight probable configurations of active heat and mass transfer areas within rotary heat exchanger channels were revealed, which are related to the initiation of frost accumulation. Consequently, the locations of the initial ' frost ' accumulation area were predicted. It was also found that the greatest impact on the frost accumulation threshold temperature has the return air relative humidity RH 2 i , although this influence is not unequivocal. The most unfavorable conditions regarding nominal temperature effectiveness in terms of frost accumulation are also unclear. In some cases, it was even demonstrated that an increase in the effectiveness can eliminate the ' frost ' accumulation area. [ABSTRACT FROM AUTHOR]

Batch experiments were carried out for the sorption of methylene blue onto Paspalum notatum. The operating variables studied were initial dye concentration, initial solution pH, adsorbent dosage and contact time. Experimental equilibrium data were fitted to Freundlich, Langmuir and Redlich–Peterson isotherms by non-linear regression method. Six error functions was used to determine the optimum isotherm by non-linear regression method. The present study shows r 2 as the best error function to determine the parameters involved in both two-and three-parameter isotherms. Langmuir isotherm was found to be the optimum isotherm for methylene blue onto P. notatum. The monolayer methylene blue sorption capacity of P. notatum was found to be 31mg/g. The kinetics of methylene blue onto P. notatum was found to follow a pseudo second order kinetics. A Boyd plot confirms the external mass transfer as the rate-limiting step in the dye sorption process. The influence of initial dye concentration on the dye sorption process was represented in the form of dimensionless mass transfer numbers (Sh/Sc 0.33) and was found to vary as . [Copyright &y& Elsevier]

Nitrogen heterocyclic organics are promising hydrogen storage carriers with the advantage of being capable of large-scale transportation over long distances using existing oil and gas facilities. However, traditional methods for the hydrogenation and dehydrogenation of organic hydrogen carriers usually require high temperature and pressure conditions and external hydrogen supplies, which hinder their large-scale applications, as well as having certain safety risks. In this paper, a reversible electrochemical hydrogen storage system using quinoxaline as a hydrogen carrier was developed with potential for use at room temperature and atmospheric pressure. Experiments revealed that the hydrogenation conversion of quinoxaline reached 95% within 120 min at −0.20 V vs. RHE, and the dehydrogenation conversion of 1,2,3,4-tetrahydroquinoxaline reached 100% within 30 min at 1.30 V vs. RHE. This means that the system achieved quick and efficient reversible hydrogen storage. The Pd/NF dual-function electrode prepared by spontaneous redox reaction still showed high catalytic activity after 8 cycles, indicating its good long-term stability. The proton donor in the electrochemical hydrogenation process of quinoxaline was water, which completely eliminates the safety risk from the use of external hydrogen. This work provides a simple and reliable strategy for efficient hydrogen storage using nitrogen heterocyclic organics. [Display omitted] • The hydrogenation conversion of quinoxaline reached 95%. • The optimum dehydrogenation conversion of 1,2,3,4-tetrahydroquinoxaline was 100%. • Pd/NF electrode was operated as a dual-function electrocatalyst. • Efficient reversible hydrogen storage was achieved at 25 °C and atmospheric pressure. • The H∗ required for the electrochemical hydrogenation of quinoxaline came from H 2 O. [ABSTRACT FROM AUTHOR]

In this paper, the "flash brazing" of SiC is successfully achieved using Ag-Cu-Ti alloy in air for seconds at an ultra-low furnace temperature of 400 °C. The interface temperature reaches over 900 °C at an ultra-fast rate via the electric field assistance. The microstructure illustrates that SiC reacts with Ag-Cu-Ti alloy to form TiC to achieve the strong bonding of the joint, and the middle part of the joint is composed of silver-based solid solution and copper-based solid solution. With the increase of brazing holding time, the amount of copper-based solid solution in the joint gradually grows, and the shear strength of the joints first increases and then decreases. The maximum strength value of 70 MPa is obtained at 400 °C−10 A-60s. This method could help to improve the efficiency of ceramic bonding greatly. [ABSTRACT FROM AUTHOR]

The development of a novel numerical model for droplet drying is the topic of this paper. The three main stages of droplet drying are distinguished, viz. unhindered evaporation of a 'wet' particle (the droplet), restricted drying at a falling rate due to the formation of a crust around a wet core, and inert heating of the dry porous particle. Each stage is mathematically detailed to replicate all phenomena occurring throughout the drying process. The focus, however, is on the falling rate drying regime which is described in terms of Stefan diffusion of water vapour through the pores of a thickening crust. To this end, the model needs the material properties. This permits the droplet characteristics to be determined by composition rather than through single-droplet drying experiments. Finally, the model is validated against five of such experiments from literature using skim milk. Good agreement is found at each comparative case for the particle mass and temperature throughout the various drying regimes providing that for good reasons in three cases a lower drying air temperature is applied than reported for the experiments. The model is capable of predicting the entire drying process at low computational cost and without requiring empirical input. [Display omitted] • New model for falling rate drying based on transport resistances in porous crust. • Stefan diffusion of vapour via crust channels, heat conduction via solid crust. • Modelling all drying stages, giving particle mass and particle temperature vs time. • Successful model validation with experimental data on single dairy particle drying. • In some cases, lower air temperature needed in model than reported from experiment. [ABSTRACT FROM AUTHOR]

• Two improved Brayton refrigeration air cycles for wastewater treatment are developed. • These two new systems have no air condensation during the expansion process. • The system coupled with a reheater can achieve the exergy efficiency of 70.7%. • The system using a solar collector can acquire the dry air with 163.6 ℃. • System using a solar collector can increase system efficiency ratio to 2.18 kg/(kW h). The Brayton refrigeration air cycle for electroplating wastewater treatment can achieve 100% recovery of water, but there is air condensation during the expansion, which can damage the expander. In order to avoid the harmful air condensation during the expansion, an improved Brayton refrigeration air cycle coupled with a reheater and an improved Brayton refrigeration air cycle using a solar collector for electroplating wastewater treatment are developed in this paper. For these two new systems, as the solar collector or reheater is used to heat the air at the outlet of the chiller, there is no air condensation during the expansion. When the wastewater needs to be treated by the air with low temperature, the reheater can be used at the outlet of the compressor to heat the air after the condensation dehumidification, which can increase the system efficiency ratio and exergy efficiency to 1.21 kg/(kW h) and 70.7%, respectively. When the wastewater needs to be treated by the air with high temperature, the solar collector can be used to heat the air after the condensation dehumidification, which can increase the air temperature at the inlet of the tower and system efficiency ratio to 163.6 °C and 2.18 kg/(kW h), respectively. [ABSTRACT FROM AUTHOR]

• A numerical model of a two-stroke marine diesel engine was developed and validated. • The effects of start of injection and scavenge air inlet temperature on exergy terms were investigated. • The exergy efficiency decreases from 43.45% to 41.36% as start of injection delays. • The exergy efficiency reduces from 42.83% to 41.44% as scavenge air inlet temperature increases. • The optimal strategies for minimizing exergy destruction and maximizing exergy. This paper presents a numerical approach of the influence of operational parameters on the exergy terms in a two-stroke marine diesel engine. Operational parameters are introduced as different start of injection (-4, -2, 0 and 2 °CA) and scavenge air inlet temperature (300, 312, 330 and 340 K) values. The energy analysis is conducted within a closed cycle by using a three-dimensional computational fluid dynamics code. The simulation results are compared with the corresponding experimental pressure data in the literature and show good agreement. Also, the exergy analysis is performed by a developed in-house computational code. Various exergy rates and cumulative exergies are detected and computed separately at operational parameters. The study reveals that varying the start of injection timing from −4 to 2 °CA at full load condition results in a decrease in exergy efficiency from 43.45 % to 41.36 %. Furthermore, an increase in scavenge air inlet temperature from 300 K to 340 K leads to a reduction in exergy efficiency from 42.83 % to 41.44 %. These findings underscore the critical influence of injection timing and scavenge air temperature on the exergy performance. In light of these results, this paper gains more insight into the impact of design parameters of a two-stroke marine diesel engine on exergy efficiency and presents a preliminary data for marine diesel engine manufacturers in the design of a two-stroke marine diesel engine that uses energy efficiently. [ABSTRACT FROM AUTHOR]

• Drop-in comparison of R513A and R516A for R134a were tested in refrigeration and air conditioning conditions. • R516 proved to be more suitable for low. • Compressor volumetric efficiency, pressure ratio and superheating for R516A have a similar behavior to R134a. refrigeration temperatures. • The differences in COP of R516A are reduced by up to 5.4% compared to R134a. This paper presents the experimental energy behavior of R516A and R513A compared to R134a as baseline refrigerant in refrigeration and air conditioning temperatures. The comparative is made in an evaporating temperatures range of 261 K to 285 K with step 4 K increases, taking condensing temperatures of 308 K, 313 K, and 318 K. Results show that the best energy performance was reached by R134a while the worst were for R513A in all experimental tests, here R516A shows the smallest difference respect to R134a being just 5.4%. Also, R134a showed lower values in discharge pressure respect to its replacements, while R516A exhibited the lower discharge temperatures. R513A showed lower useful superheating for refrigeration applications, while R516A achieved the minor useful superheating for air conditioning temperatures only below R134a. Finally, R513A reached the higher value of volumetric refrigeration capacity for air conditioning temperatures at 308 K condensing temperature. All results were obtained considering the optimal refrigerant mass charge which were 682 g, 655 g, and 632 g for R134a, R513A and R516A, respectively. [ABSTRACT FROM AUTHOR]

• A thermostat environment emulator was developed for use in load-based testing. • Typical flow conditions are provided, and appropriate building dynamics are emulated to the test thermostat. • Details of the design and operation of the emulator are described to allow future reproduction. • A 2-D dynamic model of the thermoelectric conditioning devices in the emulator is presented. • The emulator could improve load-based testing reproducibility across different test facilities. To test unitary residential cooling equipment with integrated controls and typical load responses, a load-based testing methodology has been developed where a virtual building model is used to emulate building-equipment dynamic interactions. With this approach, the temperature of an environmental chamber that simulates indoor conditions continuously tracks virtual room temperature setpoints that are adjusted based on outputs from the virtual building model. The test equipment thermostat senses the floating air temperature and communicates with the test equipment as if it were installed in the field. In order to achieve realistic dynamic behavior, it is important to properly emulate inlet flow conditions and inlet temperature dynamics provided to the thermostat that are representative of field conditions and that can be reproduced across different test facilities. The goal of the work described in this paper was to develop a thermostat environment emulator for use in load-based testing. The proposed emulator can dynamically control the thermostat inlet air temperature to the virtual room temperature setpoints using thermoelectric devices. Sample test results obtained using the emulator are presented in this paper to demonstrate its ability to track emulated building responses during load-based testing. A description of the design and control of the emulator is provided with sufficient detail to allow future researchers to reproduce it. Additionally, a two-dimensional dynamic model of the thermoelectric conditioning devices is presented that guided the overall design process. This emulator is a basis for a standardized solution for applying load-based testing that is reproducible across different facilities. [ABSTRACT FROM AUTHOR]

This paper studies the heat load-carrying capacity characteristics of a surface water body integrated with stagnant water and river water as a heat source for water source heat pumps in winter. In the cold climate, the influence of each variable on the surface water temperature was simulated and analyzed. The results showed that the solar radiation intensity, the air temperature at the water surface and the heat pump extraction time are important factors affecting the heat load-carrying capacity of surface water body. At a simulated solar radiation intensity of 500 W/m2, the water body provided the heat pump with 25 kg/s of extracted water to keep the surface water body temperature largely stable. The heat pump extraction time affects the water extraction flow rate. The flow rate for 24 h of heat extraction per day was only 0.4 times that of 10 h of heat extraction. The replenishment flow rate can change the rate of water temperature variation and the heat load-carrying capacity of the water body. When the solar radiation intensity was 0W/m2, the average temperature drop of the water body decreased from 0.23 °C to 0.15 °C by increasing the replenishment water flow rate from 0 to 10 kg/s. [ABSTRACT FROM AUTHOR]

Although photovoltaic/thermal (PV/T) air collector has simple structure and strong pressure bearing capacity, there are problems such as low thermal efficiency, unstable output temperature, due to low heat transfer performance of air and fluctuating solar irradiation. To address the above issues, a concentrating photovoltaic/thermal air collector with phase change material and vacuum double-glazing (VDG-PCM-CPV/T) is proposed in this paper. The performance of VDG-PCM-CPV/T in three continuous days is studied and compared with the module with PCM and single-glazing (SG-PCM-CPV/T) and the module with single-glazing (SG-CPV/T) by establishing the mathematic model of the daytime and night. It is proven that VDG-PCM-CPV/T has certain advantages in alleviating the downward trend of air temperature caused by the decrease of solar irradiation, due to the constant temperature storage and heat release characteristics of PCM. At night, as the vacuum double-glazing has excellent heat preservation effect, the initial temperature of PCM in VDG-PCM-CPV/T is 5.00 °C higher than that of SG-PCM-CPV/T, enable VDG-PCM-CPV/T to obtain higher thermal efficiency in the next day. While, the electrical power of VDG-PCM-CPV/T is slightly lower than that of SG-PCM-CPV/T and SG-CPV/T. The exergy efficiency of VDG- PCM-CPV/T, SG-PCM-CPV/T and SG-CPV/T at peak is 1.70%, 1.10% and 2.00%, respectively. [ABSTRACT FROM AUTHOR]

A composite thermo-hygroscopic material with loose surface, neat and single pore size distribution for lightweight envelope structure was hereby prepared in this paper by compounding inorganic minerals with polymer materials using the sol–gel method. The moisture storage capacity, isothermal humidity control characteristics of this material were studied through static isothermal humidity controlling performance experiments. Besides, its performance in terms of the air temperature, relative humidity, moisture content in the light-weight assembly building (movable panel house), laying thickness, and laying area on the indoor air parameters were studied under the action of outdoor climate conditions and indoor periodic humidity load using the effective humidity penetration thickness model. It was found that under winter conditions, the laying of CHPCMs can moderate the effects of outdoor temperature and humidity load changes on indoor temperature, relative humidity and moisture content, and effectively delay the fluctuation of indoor air parameters. CHPCM exhibits an optimal laying thickness value, and the deviation from the optimal thickness value can weaken its ability to regulate indoor environmental parameters. The average air relative humidity of the naturally ventilated room with a laying area of 24 m2 is about 4.6 % lower than the average air relative humidity with a laying area of 12 m2. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study and experimental validation of humidification-dehumidification solar desalination unit. This unit consists of a solar evaporator and a tubular condenser. The design particularity of the evaporator is the integration of the humidifier in the solar air and water collectors. A mathematical model based on the heat and mass balances has been developed in the desalination unit. The finite difference method is adopted for discretization of the equations and the resolution is done by MATLAB software. Numerical results are compared with literature and experimental results. An acceptable agreement is observed. A parametric study was conducted to test the influence of the different operating parameters on the unit production and the Gained output ratio GOR. The production of the desalination system increases with air and water temperatures of the water in the evaporator and the inlet humid air temperature at the dehumidifier. It should be noted that the production reaches its maximum value for a feed water mass flow rate in the humidifier of 5.5 kg/h and a cooling water mass flow rate in the dehumidifier of 0.2 kg/s. [ABSTRACT FROM AUTHOR]

This paper correlated the Meniere attack with meteorological parameters i.e. atmospheric pressure, temperature, relative humidity and rainfall, to investigate which parameters that trigger the Meniere attack. During the past three years, totally 283 (2015), 351 (2016) and 319 (2017) patients with Meniere's disease (MD) were encountered at a clinic of the university hospital, accounting for 13%, 17% and 16% incidence in relation to overall annual neurotological cases, respectively. The onset of Meniere attack was then correlated with meteorological parameters. The mean seasonal incidence of Meniere attack in relation to overall seasonal neurotological cases in 2015-2017 were 14.8 ± 2.8% (spring), 17.5 ± 2.2% (summer), 16.0 ± 1.8 % (autumn) and 12.8 ± 2.0% (winter), indicating that summer season had a higher incidence of Meniere attacks than winter season. Onset of Meniere attacks correlated significantly with the atmospheric pressure (r = -0.4484, p = 0.0061) and temperature (r = 0.4736, p = 0.0035), and the atmospheric pressure was highly negatively correlated with the temperature (r = -0.9421, p < 0.0001). In contrast, no correlation was identified between the onset of Meniere attacks and relative humidity or rainfall. The atmospheric pressure in the same month with typhoon compared with that without typhoon revealed a median reduction of 13.1 hectopascal. Atmospheric pressure and temperature are correlated with the onset of Meniere attack. Summer season has a higher incidence of Meniere attack than winter season, likely because low atmospheric pressure in summer may aggravate endolymphatic hydrops, especially when accompanied by typhoons in the northwest Pacific region. [ABSTRACT FROM AUTHOR]

• A revised temperature model is built to study the thermal stratification. • The reservoir has a reverse thermal stratification and two overturning in a year. • Low water level can weaken the stability and lengthen the spring overturning. • High inflow volume can strength the stability and defer the spring overturning. Thermal structure plays a significant role in the aquatic ecosystem of reservoirs. In this paper, thermal structure of a large reservoir for water supply in northeast China has been studied. Considering the reservoir has a 150 days icebound period and the ice cover can affect the heat transfer process, we built a revised numerical simulation model based on EFDC to study the temporal and spatial variation of thermal stratification. The absolute mean error (AME) and mean absolute relative error (MARE) between modeled and observed water temperature are 0.40 °C and 7.15%, respectively. The results indicate that the validated model can successfully reproduce the temporal and spatial variation of water temperature. The model results indicate that the reservoir has a reverse thermal stratification in icebound season and there are two over-turning events in a year. Six hypothetical scenarios including the extreme change in the air temperature, inflow discharge, and the water level had been built to quantify the influences of changes in climate and hydrology conditions on the thermal structure. This paper provides a simplified method for the simulation of the water temperature in the reservoir with an icebound season, which can provide a reference for other reservoirs. [ABSTRACT FROM AUTHOR]

Thermochemical energy storage has a great potential in thermal energy storage attracting extensive attention in building's applications. However, performance issues of the thermochemical reactor should be tackled to improve the overall performance. To enhance the heat transfer within the reactor, this study proposes a thermochemical reactor integrated with copper fins. The reactor features both heated air and water output in a discharging process. Using Zeolite 13X as the thermochemical material, experimental tests have been conducted and presented in this paper to investigate the performance of the reactor. According to the experiment, the copper fins reactor achieves better performance in both charging and discharging compared with the reactor without fins. In charging, copper fins reactor reduces charging time by 0.75 h for the outlet air temperature reaching to the comparable level of the reactor without fins at 156.2 °C. In discharging, the copper fins reactor achieves the peak outlet air temperature at 54.6 °C and the peak outlet water temperature at 39.4 °C. Additionally, the reactor achieves energy storage density at 233 kWh/m3 for material level and 128 kWh/m3 for the reactor level. This paper provides valuable information for improving the reactor performance to achieve an optimal performance of a thermochemical energy storage system. • This paper presents an experimental study of a copper fins thermochemical reactor. • Copper fins pipe is integrated with the reactor to enhance the reactor performance. • Experimental tests of charging and discharging have been conducted and presented. • The reactor achieves peak outlet air temperature at 54.6 °C and peak outlet water temperature at 39.4 °C. • The reactor achieves energy storage density at 233 kWh/m3 for material level and 128 kWh/m3 for the reactor level. [ABSTRACT FROM AUTHOR]

This paper focusses on hot underground tunnels and studies the effect of ground source heat pump (GSHP) intermittent operation and changing tunnel air temperature profile on energy tunnel thermal efficiency. The effects of heat pump operation on the tunnel surrounding soil and the soil recovery rate when the heat pump is not in operation were also studied. A 3D numerical model was developed to simulate the transient heat transfer intermittent operation of an energy tunnel. The intermittent operation was reproduced by controlling the convective heat flux at the boundary between the absorber pipe and the tunnel lining. Variation in the tunnel air temperature was defined in the model as a periodic sink amplitude. Results show that in energy tunnels, strategic intermittent operation increases thermal efficiency and allows the surrounding soil to thermally recover and prevent any adverse effect on the system. A high daily intermittent operation ratio increases the average thermal output but might lead to higher operating costs. Therefore for a given site, it is important to determine the optimum intermittent ratio. The paper also shows how the variation in tunnel air temperature affects the thermal performance of the energy tunnel. The importance of including this variation (rather than assuming a constant average value) when estimating the geothermal potential of underground tunnels was also highlighted. Insights are also provided on the soil temperature recovery rates after prolonged operation. These would serve as a basis for working out a seasonal intermittent operation strategy to optimise the use of ground source heat pumps in underground tunnels. • An improved finite element model to simulate heat transfer in energy tunnels. • Effect of intermittent operations on thermal efficiency of energy tunnels. • Influence of seasonal variations in air temperature on thermal performance. • Intermittent operation minimises thermal disturbance on the surrounding soil. • Different operation scenarios serve as a basis for optimum operation. [ABSTRACT FROM AUTHOR]

• Optimal Window-to-Wall Ratios were recommended for various building orientation. • Integrated models with different glazing area and orientation combinations were proposed. • Daylight factor, air temperature and air velocity were computed for each test scenario. • Three optimal intervals of Window-to-Wall Ratio were determined respectively. • Intersection interval of the three subsets is the optimal interval of Window-to-Wall Ratio. Since the ratio of glazing and opaque areas on building facade has significant impact on the indoor visual and thermal comforts as well as energy consumption, the optimal Window-to-Wall Ratio is necessary to be explored for the rural residences with a large quantity in China. Due to the traditional dwellings has been representative of housing samples among rural residences, Sizhai traditional dwellings situated in Zhejiang Province were chosen as the study buildings in this paper. The building model is rotated to 20° increments clockwise to create 18 building orientation intervals. Furthermore, the Window-to-Wall Ratio of front facade for the building model was divided into 8 intervals at increments of 0.1, from [0.1–0.2] to [0.8–0.9]. Through indoor environment simulation, the daylight factor, air temperature and air velocity were computed for the test scenarios with different building orientation and Window-to-Wall Ratio combinations. Three optimal intervals of Window-to-Wall Ratios at a series of building orientations corresponding to the daylight factor, mean maximum indoor temperature and mean indoor air velocity are determined respectively, based on the criteria of national codes and thermal comfort ranges. The intersection interval of the three subsets is the optimal interval of Window-to-Wall Ratio for the study building. In addition, for verifying the accuracy of research results, two validation techniques (i.e., comparison of experimental measurement data, and comparison of computational results from other simulation tools) were adopted in this paper. [ABSTRACT FROM AUTHOR]

• A new model of the link between demand groups and air temperature is presented. • This is shown to vary depending on time of day and consumer group composition. • Demand groups have been derived to model generic UK distribution network load. • Additional connections possible when using DTRs over present ratings. • Ancillary service requirements for increased customer connections are also presented. Real-Time and Dynamic Thermal Ratings have been discussed in the literature as potential methods to increase network headroom, typically to allow the connection of distributed generators, mitigating the need for network reinforcement. The work presented in this paper considers the effectiveness of these techniques in terms of possible consumer connections as opposed to generation. A generalized temperature sensitive load modelling procedure is presented in order to derive representative demand group time-series profiles, and as such model the possible connections across the entire seasonal cycle. The procedure has been tested against real-world data taken from a rural 20 kV feeder in the North of England detailing the period October 2013–October 2014. This work was carried out as part of the LCNF funded Customer-Led Network Revolution (CLNR) smart grid project. [ABSTRACT FROM AUTHOR]

This paper presents a critical advancement in Building Energy Modeling (BEM) through an empirical validation approach using a high-quality dataset from a multizone commercial office building in Oak Ridge, TN, USA. BEM is widely utilized in diverse construction applications, but its effectiveness relies on the accuracy of its predictions. The study focuses on empirical validation of input parameters in BEM, including building envelope data, infiltration modeling, and rooftop unit system performance curves. The validation of simulation input parameters leads to substantial improvements in the accuracy of simulation results. Notable both NMBE and cv (RMSE) values are reduced by 0.5 % for indoor air temperature and 17 % for indoor air relative humidity compared to the previous model. At the system level, both NMBE and cv (RMSE) values are reduced by 2 % for fan energy consumption and 4 % for cooling energy consumption, compared to the previous model. A literature review highlights a significant gap in empirical validation studies, which predominantly concentrate on either component-level or whole building validation. Furthermore, many studies employ simplified setups that may not faithfully represent the complexities of multizone commercial buildings. This paper distinguishes itself by emphasizing the critical importance of component-level input parameter validation. It underlines the need to validate data related to building envelope components and HVAC system performance curves, resulting in more accurate simulation outcomes. The utilization of actual multizone commercial building data enhances the study's practical relevance. In summary, this research underscores the pivotal role of input parameter validation in enhancing the accuracy and reliability of BEM. • The EnergyPlus simulation model input parameters have been empirically validated. • Building envelope input parameters have been evaluated. • Tracer gas and blower door tests have been performed to update infiltration model. • The rooftop unit performance curve has been developed using field datasets. • The simulation results are well-matched with field data at zonal- and system-level. [ABSTRACT FROM AUTHOR]

• The oasis cooling effect was investigated within 12 scenarios in three seasons. • The human thermal comfort was evaluated based on the PET index in arid climates. • A neutral range can be ensured in well-defined spatial and microclimatic aspects. • Palm tree grids of 10 and 12 m are the optimal scenarios for the neutral range. • The neutral range is mainly affected by T mrt with a rate of 53%. With climate change and the recurring heat waves in arid lands, human well-being and activities in oasis settlements can be critical subjects for the ongoing years. This paper introduces a methodological approach to investigate the potential passive cooling effect inside the oasis palm groves, their spatial characteristics, and microclimatic thresholds. Based on the Physiological Equivalent Temperature (PET) index, the paper evaluates oasis palm groves' ability to ensure a neutral human outdoor thermal comfort zone. The research aims to determine guidance of an optimal and nearly optimal thermal comfort threshold based on a series of parametric scenarios of oasis configurations. The study provides a cross of 12 ideal oasis scenarios. The paper evaluates the oasis cooling effect and thermal comfort and recommends aligning urban planning with thermal thresholds. Results reveal that PET neutral zone can be assured into ranges of 29°C to 37°C, 19°C to 20°C, 55% to 58%, and 1m/s to 2m/s of mean radiant temperature, air temperature, relative humidity and air velocity , respectively. The results refer policymakers and urban planners to invest in the passive cooling effect of the oasis palm grove in future urban design strategies to maintain the maximum neutral comfort hours during heat waves. [ABSTRACT FROM AUTHOR]

Photovoltaic double skin façade (PV-DSF) offers a versatile solution to address the escalating energy demands of buildings by combining power generation and indoor air temperature adjustment functionalities. Most prior research concentrated on its summer performance, while the winter season receives less attention. This paper concentrates on its operation performance in winter, to provide an experimental framework for its efficient operation. In this regard, the performance of internal circle and thermal buffer mode (both are possible operation modes in winter) were compared via control variable experiments, and the feasibility of mechanical ventilation is also examined regarding the trade-off between the energy consumption of fans and additional energy benefit. These experiments were performed in the full-size experiment rig at Harbin, China, a city with severe cold climate. The experiment results conclusively demonstrate that the internal circle mode can outperform the thermal buffer mode on a cold, sunny day by 10.9%, and the total energy-saving potential can be further increased by 12.6% if fans are activated to enhance cavity airflow. While the experimental data during partly cloudy emphasizes the significance of a suitable operation schedule and shows that PV-DSF can only be switched to internal circle mode when cavity air is fully heated. • The performance of photovoltaic double skin façade (PV-DSF) in winter is studied. • A fully-size experiment rig is constructed to perform comparison experiment. • The internal circle mode can outperform thermal buffer mode by 10.9% in clear day. • The fans can speed up cavity airflow and improve total energy efficiency by 12.6%. • The results of this paper emphasize the importance of a real-time control strategy. [ABSTRACT FROM AUTHOR]

A new absorber surface is designed for solar air heaters to make them compact and enhance heat transfer parameters. The current paper presents the novel absorber design using a tubular surface having three-pass in counter-flow. The absorber tubes are constructed from thin sheets of aluminium; 15 tubes are closely spaced in line with each other to establish three-pass, i.e. five tubes per pass. The research paper investigates numerically and experimentally the thermo-hydraulic performance of a Tubular Three-pass Solar Air Heater (TTPSAH). The numerical model was developed using MATLAB to predict the performance and outlet air temperature. The error in numerical and experimental evaluation is approximately 5%, showing promising results. It was found that the TTPSAH accelerates heat transfer in a compact surface area. The maximum thermal efficiency was evaluated as 60.04%, 41% and 33.3% for an airflow rate of 0.006 kg/s, 0.004 kg/s, and 0.002 kg/s respectively. Thermal enhancement with a maximum outlet air temperature of 110.6 °C, 91.4 °C and 80.2 °C was recorded at a mass flow rate of 0.002 kg/s, 0.004 kg/s and 0.006 kg/s in glazed conditions. Furthermore, the research includes an estimation of the energy cost per kilowatt-hour (kWh), which amounts to $0.017, $0.025, and $0.0311 for mass flow rates of 0.006 kg/s, 0.004 kg/s, and 0.002 kg/s, respectively. • To increase the applicability of solar energy a novel tubular three-pass solar air heaters was designed. • The mathematical model and experimental results are in good agreement. • The maximum outlet air temperature of 110.6 °C attained for a flow rate of 0.002 kg/s. • The thermohydraulic performance parameters of TTPSAH was also studied. [ABSTRACT FROM AUTHOR]

The present paper analyzes experimentally the morphology of a set of non-premixed diffusion reactions of hydrogen enriched natural gas (NG). For the analysis the H 2 content was varied from 0 to 100 vol.-% and the mixture issues in a co-flow at variable preheating temperatures, from ambient conditions of 25 °C and up to 400 °C. For the various NG-H 2 blends the thermal power input was held constant at 0.8 kW. For processing the images, a bitmap filter was used to isolate visible flame height, visible width variations, and soot free length fraction (SFLF). The results show that visible flame height always decreases when increasing H 2 content in NG at any preheating temperature. The effects of air preheating summarize as follows: for NG enriched up to 75 vol.-% H 2 , the visible flame height reduces when increasing the air preheating temperature from 25 °C to 200 °C, then at 300 °C the visible flame height increases when rising the air temperature up to 400 °C. For the 100% H 2 non-premixed flame the visible height presents a linear trend to increase as air temperature rises. Roper's theory for non-premixed flames in circular ports correlates reaction length to air preheating temperature and fuel composition variations, however those trends neglect buoyancy and diffusion phenomena, which results in significant error on predicting the effects of hydrogen addition to NG on the reaction length. A modified correlation is proposed to predict accurately the effects of air preheating and H 2 fraction on visible flame height. Finally, a multidimensional scaling analysis shows that hydrogen addition up to 50 vol.-% does not modifies the visible flame morphology significantly when compared to pure NG. • Adding H 2 up to 50 v% to NG does not significantly change the flame shape. • NG-H 2 non-premixed flame length has a parabolic trend with air preheating. • Air preheating and hydrogen addition make non-premixed flames shorter and thinner. • The soot free length fraction decreases when increasing air preheating temperature. • Accurate correlation for predicting visible flame height of NG-H 2 blends. [ABSTRACT FROM AUTHOR]

Ventilation cooling is a crucial measure to solve the high temperature hazards in high geothermal tunnels of the Sichuan-Tibet Railway during construction. In this paper, two numerical models of a cross tunnel in the Layue Tunnel were developed using the finite volume method to investigate the impact of tunnel drilling process and ventilation parameters on tunnel ventilation under various surrounding rock temperatures. The heat generated by the tunnel drilling process significantly increases the temperature of the tunnel. Furthermore, the presence of construction equipment also affects the velocity distribution. These factors need to be considered in the calculation. The simulation results indicate that the tunnel temperature decreases as the inlet air velocity increases, following a quadratic pattern. Increasing air velocity can also improve the efficiency of tunnel ventilation. Additionally, with increasing inlet air temperature and surrounding rock temperature, the tunnel temperature increases linearly. According to the simulation results, the functional relationship between tunnel temperature, ventilation parameters and surrounding rock temperature has been established. The fitting functions can be used as references for the ventilation design of the Layue Tunnel construction. To reduce the temperature in the work area to 28 ℃ within 40 min, as the inlet air velocity not exceeding 20 m/s and the surrounding rock temperatures are 50 ℃, 60 ℃ and 70 ℃, the inlet air temperature should be lower than 24.9 ℃, 23.7 ℃ and 22.4 ℃, respectively. [ABSTRACT FROM AUTHOR]

Heat waves, combined with an increasing share of weather-dependent renewable energy sources, lead to disruptions in the operation of energy systems. This paper estimates how energy consumption in Poland changed during four heat waves (2010–2022). It also analyzes how often wind conditions may occur in the summer, that interrupt energy production by land-based wind farms. Moreover, authors are looking at future changes of climate indices responsible for increased energy consumption and possible reduction of energy production in wind farms. During the 2010 heatwave, the increase in energy consumption during the hottest days did not exceed 4 %. Later summer demand increased; in 2019, it was 8 % higher than during the 2015 heatwave. In 2016–2022, energy consumption at the average daily air temperature above 26 °C was over 8 % higher on working days than at 18 °C. Recently, even in regions with favorable wind conditions, the number of summer days with low wind speed (2 ms−1) exceeds 14. For Poland, the number of days with low wind speeds will increase by about ten. Therefore, the increasing demand for energy on hot days, combined with their more frequent occurrence, may have a negative impact on the stability of the energy system in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

• The 1D model of an open heat storage reactor containing zeolite 13X is presented. • Model validation is based on simultaneous mass and heat transfer measurements. • Three adsorption isotherm models (Langmuir, DA, modified BET) are compared. • The modified BET model provides the best results (> DA > Langmuir). • Proper characterization of the sorbent (isotherms, heat of sorption) is essential. Efficient modeling of thermochemical heat storage reactors is required to predict their performance in various operating conditions and optimize their design. Such modeling necessitates an accurate description of the properties of storage materials, which is still challenging to this day. This paper specifically investigates the influence of the choice of the sorption isotherm model. To this aim, the Langmuir, Dubinin-Astakhov (DA) and modified Brunauer-Emmet-Teller (BET) isotherm models are studied. The 1D model of an open fixed bed reactor based on the hydration and dehydration of zeolite 13X is presented. The model couples heat and mass transfer and uses the linear driving force approximation. Experimental investigations are also performed to characterize the sorption equilibrium of the material, its adsorption kinetics at the reactor scale and the resulting heat storage performance. The model is validated simultaneously on the basis of mass and of heat transfer measurements (i.e., breakthrough and temperature curves). The BET isotherm is shown to be the most relevant for the description of water adsorption on zeolite 13X because it considers multilayer adsorption. It fits the experimental isotherm best. At the reactor scale, the modified BET model also provides the best results, closely followed by the DA model. Still, for consistent predictions, the characterization of the chosen sorbent (i.e., the experimental data used to correlate the isotherm model or the heat of sorption) is of utmost importance and the initial water loading must be adequately specified. [ABSTRACT FROM AUTHOR]

• Made a small-area analysis of greenspace exposure and heat-mortality associations. • Examined which type and location of greenspace matter most in heat health risk reduction. • Unlike grassland, forests yielded significant health benefits under heat. • Greenspace, especially forests, within a 1 km radius of residents matter most. • More apparent effects were observed for greenspace nearby than area-level exposure. While vegetation type, population density and proximity to greenspaces have been linked to human health, what type and location of greenspace matter most have remained unclear. In this context, there are question marks over investment-style metrics. This paper aims at establishing what vegetation type may matter most in modifying heat-mortality associations, and what the optimal buffer distances of total and specific types of greenspace exposure associated with reduced heat-related mortality risks are. We conducted small-area analyses using daily mortality data for 286 Territory Planning Units (TPUs) across Hong Kong and 1 × 1 km gridded air temperature data for the summer months (2005–2018). Using a case time series design, we examined effect modifications of total and specific types of greenspaces, as well as population-weighted exposure at varying buffer distances (200–4000 m). We tested the significance of effect modifications by comparing relative risks (RRs) between the lowest and highest quartiles of each greenspace exposure metric; and explored the strength of effect modifications by calculating the ratio of RRs. Forests, unlike grasslands, showed significant effect modifications on heat-mortality associations, with RRs rising from 0.98 (95 %CI: 0.92,1.05) to 1.06 (1.03, 1.10) for the highest to lowest quartiles (p -value = 0.037) The optimal distances associated with the most apparent effects were around 1 km for population-weighted exposure, with the ratio of RRs being 1.424 (1.038,1.954) for NDVI, 1.191 (1.004,1.413) for total greenspace, and 1.227 (1.024,1.470) for forests. A marked difference was observed in terms of the paired area-level and optimal distance-based exposure to total greenspace and forests under extreme heat (p -values < 0.05). Our findings suggest that greenspace, particularly nearby forests, may significantly mitigate heat-related mortality risks. [ABSTRACT FROM AUTHOR]

Seasonal variations of atmospheric muons are traditionally interpreted in terms of an effective temperature that relates the atmospheric temperature profile at a given time to the dependence of muon production on atmospheric depth. This paper aims to review and generalize the treatment of muon production and effective temperature that has been used to interpret seasonal variations of atmospheric muons by many experiments. The formalism is developed both in integral form – for application to compact detectors at a fixed depth that record all muons with E μ > E μ min – and in differential form — for application to extended detectors like IceCube, KM3NeT, and Baikal-GVD, where the rates are proportional to energy-dependent effective areas. [ABSTRACT FROM AUTHOR]

The high temperature of PV panels during power generation not only reduces their efficiency but also leads to increased heat transfer to the room. The impact of using PV panels on the indoor thermal environment should not be overlooked. A novel roof structure is proposed in this paper, which is composed of PV panels, phase change materials (PCMs) and ventilation layer from top to bottom. The thermal performance of PV-PCM- ventilation roof room is compared with that of PV roof room and PV-PCM roof room under active and passive conditions respectively. Results show that under passive conditions: Compared to PV roof, the PV-PCM-ventilation roof internal surface temperature fluctuation decreases by 44.12%, the correlation coefficient between the back surface temperature of PV panel and outdoor air temperature decreases from 0.79 to 0.69, and the correlation coefficient with solar radiation decreases from 0.66 to 0.60. Compared to PV-PCM roof, the back surface temperature of the PV panel decreases by 3.31 °C during the day. Under active conditions, when the set temperature is 26 °C and 28 °C, the energy consumption of the PV-PCM-ventilation roof room decreases by 15.61% compared to the PV roof room. In summary, the new roof demonstrates good insulation and energy-saving performance. [ABSTRACT FROM AUTHOR]

• A field trial was conducted to validate the feasibility of employing infrared thermography (IRT) for fouling detection. • An infrared thermal imager, temperature sensors, and a weather station were installed to monitor temperatures and meteorological data in real time. • Inversion models were developed to invert the key thermodynamic parameters of the ballasted track. • The impacts of various meteorological factors and weather conditions on the detection effectiveness of IRT were analyzed. The fouled ballast bed significantly impacts the operational condition of the ballasted track. Timely detection of the fouled ballast bed can greatly reduce maintenance workloads and capital expenditure. This study aims to assess the feasibility of employing infrared thermography (IRT) for detecting fouling. Nonetheless, existing research has been conducted under conditions noticeably different from the actual field. Moreover, the climatic conditions surrounding the ballasted track are beyond control. Hence, this paper innovatively utilized thermodynamic simulation to simulate as many conditions as possible. Firstly, temperatures and external meteorological data were obtained on a newly constructed railway line using an infrared thermal imager, temperature sensors, and a weather station. Thermodynamic inversion models were then established based on field structures to determine crucial thermodynamic parameters. The results demonstrate excellent alignment with the existing literature. Expanding upon this groundwork, the study explored the impact of various meteorological factors and weather conditions on the detection effectiveness of IRT. The results indicate that the solar radiation intensity (S) and air temperature (T) have the most significant effect on the surface temperature of the ballast bed (STB) and the temperature difference between the clean and fouled ballast beds (CF-TD). The rainfall (R) can change the thermodynamic properties of the ballast bed. Without considering R, the higher the S or T, the greater the CF-TD. Specifically, on sunny days, the maximum CF-TD can achieve 3.26 °C, while on cloudy days or at night, it is only 0.79 °C and 0.28 °C, respectively. Furthermore, the impact of wind speed (W) on the CF-TD was found to be disregarded in regions with low wind speeds but significant in regions with high wind speeds. In summary, IRT shows promise for rapid initial assessments of ballast bed conditions on sunny days, particularly following rain. While on cloudy days or at night, higher resolution infrared thermal imagers may be required, or other detection indicators may need to be investigated. [ABSTRACT FROM AUTHOR]

Detecting the correct peaks of reflections in room impulse responses (RIRs) is of interest for several applications. The time-of-flight (ToF) of these reflections peaks are needed, for example, in the application of Acoustic travel-time TOMography (ATOM) to reconstruct the indoor air temperature. Strictly speaking, the ToF of early reflections is used as an input dataset to reconstruct the air temperature using inverse algorithms. Here, the most popular benefit of using the ToF of early reflections is the possibility to reconstruct the indoor air temperature fields using a minimum number of transducers. In this context, there exist a wide variety of approaches to estimate the correct ToF of the reflection peaks. While literature empirically highlighted the potential of the majority of these methods to detect the correct peaks, they have not been compared to each other in terms of their advantages and limitations. This review paper provides a critical overview and a snapshot of the used detection methods of the ToF of reflection peaks with special focus on application of ATOM technique in the indoor areas. Meanwhile, it offers details and guidelines to improve the detection process of the ToF of reflection peaks in the RIRs reflectogram only in case the length of the short analysis time-windows is identified appropriately. Alternatively, a method designed to detect peaks in the measured reflectogram, excess coefficient technique, dynamic time warping approach and plane wave decomposition technique provide enhanced consistency and precision for the estimated ToF of early reflections. However, we discuss the short analysis time-window procedure that is particularly well-suited to improve the estimation of the ToF of early reflections. Moreover, future outlook and research gaps are highlighted in the present review. [Display omitted] • A complete overview of the state-of-the-art approaches in detecting time-of-flight (ToF) in room impulse responses (RIRs). • A conceptual comprehensive survey of the ATOM application, where the ToF of reflection peaks is highlighted and discussed. • A conceptual comprehensive survey of each detection technique of ToF based on its advantages and disadvantages. [ABSTRACT FROM AUTHOR]

Air-cooled chillers are extensively employed to meet cooling demand in commercial and tertiary sectors. To enhance their performance during part-load operation, variable-speed drives have been integrated into compressors and condenser fans. In existing systems, condenser fans are either operated at a fixed speed or modulated to maintain a predetermined condensing pressure or temperature difference between the refrigerant and outdoor air. In the search for increased efficiency, it is worth investigating innovative control strategies aimed at minimizing energy consumption. A preliminary mapping of chiller performance at different fan speeds, loads, and operating conditions is required to achieve this goal. In this respect, this paper investigates the operation of air-cooled chillers equipped with variable-speed condenser fans, both in the case of constant- and variable-speed compressors. An ad hoc matrix test is adopted to cover appropriate ranges conditions, in terms of load and outdoor air temperatures. Performance maps are developed for a 50-kW c chiller using a 1-D simulator. As the main findings, it may be stated that (i) in the case of the variable-speed chiller, the energy efficiency ratio increases almost linearly with fan speed, resulting in an 8.8% increase when increasing the speed from the nominal to the maximum; (ii) in the case of constant-speed chillers, the system exhibits a different behavior with the cooling capacity and the energy efficiency ratio increasing with the fan speed between 380 and 980 rpm and then decreasing (slightly or sharply, at full and part load respectively) with fan speed between 980 and 1280 rpm, and a percentage increase of EER in the range 7.8–45% is observed. Also, the sensitivity of such results to the system design is investigated, analyzing a chiller equipped with a larger condenser that resulted in achieving minimum energy consumption at an optimal 980 rpm fan speed. Finally, for a constant-speed chiller serving an office building in the Mediterranean, the proposed fan control strategy could yield an electricity saving of up to 12.1% compared to the base case, confirming the potential for energy savings through optimized and system-tailored management of condenser fan speed. • The effect of variable-speed fans on the performance of air-cooled chillers is investigated. • Maps are developed for chillers with both variable-speed and constant-speed compressors. • Fan speed significantly influences the cooling capacity of constant-speed chillers. • In variable-speed chillers, it is advisable to always run the condenser fan at high speed. • The enhanced fan strategy enables 12.1% energy savings for a chiller in an office building. [ABSTRACT FROM AUTHOR]

• Scalable thermoplastic polyurethane films containing nanoparticles are recently developed. • Innovative advanced films present superior optical performance. • New films contribute to reduction in daytime overheat. Radiative cooling, which does not entail any energy consumption, has received considerable attention as a promising, practical, and sustainable solution to heatwaves. This study investigated single layer nanoparticles–polymer films that reflected sunlight and emitted radiation through atmospheric windows. In this paper, the fundamental principles of Mie theory, the cooling power model, and the thermal balance model of metamaterial films were first introduced. Then, the influence of fabrication parameters (nanoparticle materials, mass fractions, and thicknesses) to the reflectivity in solar band was experimentally explained. An increase in the mass fraction enhanced the reflectivity corresponding to the stretching vibration regions of C H, N H, and O H, while an increase in the thickness improved the reflectivity at non-absorption bands. Laboratory measurements indicated that the combination of TiO 2 , a fluorescent brightener, and a far-infrared ceramic powder on 100 μm thermoplastic polyurethane film achieved excellent solar reflectivity of 92.2 % and infrared emissivity of 96.1 %. Experimental testing and Fluent simulation showed that the film achieved a substantial cooling capacity in both Beijing and Tianjin. Under a transparent atmospheric window, it exhibited a subambient temperature of 3.7 °C when the air temperature reached its peak. The maximum daytime and night-time subambient temperature were 13.4 °C and 14 °C respectively. [ABSTRACT FROM AUTHOR]