Heating Mode Research Articles

Pulse-Driven MEMS NO2 Sensors Based on Hierarchical In2O3 Nanostructures for Sensitive and Ultra-Low Power Detection

As the mainstream type of gas sensors, metal oxide semiconductor (MOS) gas sensors have garnered widespread attention due to their high sensitivity, fast response time, broad detection spectrum, long lifetime, low cost, and simple structure. However, the high power consumption due to the high operating temperature limits its application in some application scenarios such as mobile and wearable devices. At the same time, highly sensitive and low-power gas sensors are becoming more necessary and indispensable in response to the growth of the environmental problems and development of miniaturized sensing technologies. In this work, hierarchical indium oxide (In2O3) sensing materials were designed and the pulse-driven microelectromechanical system (MEMS) gas sensors were also fabricated. The hierarchical In2O3 assembled with the mass of nanosheets possess abundant accessible active sites. In addition, compared with the traditional direct current (DC) heating mode, the pulse-driven MEMS sensor appears to have the higher sensitivity for the detection of low-concentrations of nitrogen dioxide (NO2). The limit of detection (LOD) is as low as 100 ppb. It is worth mentioning that the average power consumption of the sensor is as low as 0.075 mW which is one three-hundredth of that in the DC heating mode. The enhanced sensing performances are attributed to loose and porous structures and the reducing desorption of the target gas driven by pulse heating. The combination of morphology design and pulse-driven strategy makes the MEMS sensors highly attractive for portable equipment and wearable devices.

Influence of the Building’s Thermal Insulation on Intermittent Heating Mode Efficiency

Abstract The results of mathematical modeling of a building’s thermal insulation influence on the efficiency of intermittent heating mode are presented. This work aim is to assess the influence of thermal insulation on the efficiency of using the intermittent heating mode for the educational building of the Odessa National Polytechnic University’s Heat Engineering Laboratory. The paper analyzes the factors related to improving the efficiency of the programmed heat supply mode. Modeling of the operating modes for heat supply system operated in intermittent heating mode is carried out. There was performed the mathematical modeling of the heating system operation modes for the most unfavorable climatic conditions at low outdoor temperatures, with respective system efficiency indicators obtaining. The potential of energy saving level for administrative, educational, and office buildings depending on the thickness of thermal insulation of external and internal walls is studied. Recommendations have been elaborated for the use of buildings thermal insulation to improve the efficiency of intermittent heating.

Single-Loop Triple-Diameter Pulsating Heat Pipes at Reduced Heat Input: A CFD Study on Inner Diameter Optimization

The geometric configuration, particularly the inner tube diameter, plays a significant role in the thermal performance of pulsating heat pipes (PHPs). Previous experimental research has demonstrated that single-loop triple-diameter PHPs (TD-PHPs) outperform single-loop single-diameter PHPs (SD-PHPs) and dual-diameter PHPs (DD-PHPs) in terms of thermal performance under moderate heating input powers ranging from 25 W to 75 W. However, a reduction in heat input from 75 W to 25 W leads to a diminished impact of TD-PHPs on the thermal performance. Therefore, to improve the overall performance of TD-PHPs, this study used two-dimensional transient computational fluid dynamics simulations to identify the optimal inner tube diameters for TD-PHPs at a low heat input by evaluating the thermal resistance of five TD-PHPs with various inner diameters. The findings reveal that the TD-PHP configuration exhibits minimum thermal resistance, with inner diameters of 4.5 mm for the upper arch (the condenser section), 4.0 mm for the wide branch, and 2.5 mm for the narrow branch, primarily due to its full circulation flow pattern. Furthermore, the overall heat transfer performance of the optimal TD-PHP was compared with that of an SD-PHP at low heat inputs (10 and 18 W), indicating that although the optimal TD-PHP shows lower thermal resistance, it does not significantly affect the start-up time.

Association Between Self-Reported Protective Behavior and Heat-Associated Health Complaints Among Patients With Chronic Diseases in Primary Care: Results of the CLIMATE Pilot Cohort Study.

As a result of climate change, exposure to high temperatures is becoming more common, even in countries with temperate climates. For patients with chronic diseases, heat poses significant health risks. Empowering patients is a crucial element in protecting the population from the adverse effects of heat. In this context, self-reports of protective behavior are often used to gain a mutual understanding of patients' issues. However, the extent to which self-reported behavior is associated with health complaints remains unclear. This study aims to describe the association between light to moderate heat and health complaints in everyday life, and to analyze whether self-reported protective behavior and related psychosocial factors are linked to these complaints. We conducted a pilot cohort study using internet climate data merged with an online survey of patients with chronic diseases recruited through general practitioner practices. Patients were eligible if they were 18 years or older and had at least one chronic disease. The heat was modeled using temperature and humidity data. Health complaints were assessed through up to 7 follow-up evaluations on the hottest day of each week during the observation period. Data were analyzed using 3 nested models with mixed effects multivariable linear regression, adjusting for random effects at the climate measuring station and participant levels. Model 1 included heat exposure, sociodemographic data, and chronic diseases. Model 2 added protective behavior and health literacy, while model 3 incorporated self-efficacy and somatosensory amplification (ie, the tendency to catastrophize normal bodily sensations such as insect bites). Of the 291 eligible patients, 61 (21.0%) participated in the study, providing 294 observations. On average, participants were 61 (SD 14) years old, and 31 (51%) were men. The most prevalent conditions were cardiovascular diseases (n=23, 38%) and diabetes mellitus (n=20, 33%). The most commonly reported symptoms were tiredness/fatigue (232/294 observations, 78.9%) and shortness of breath (142/294 observations, 48.3%). Compared with temperatures of 27°C or lower, a heat index between over 27°C and 32°C (β=1.02, 95% CI 0.08-1.96, P=.03) and over 32°C (β=1.35, 95% CI 0.35-2.35, P=.008) were associated with a higher symptom burden. Lower health literacy (β=-0.25, 95% CI -0.49 to -0.01, P=.04) and better self-reported protective behavior (β=0.65, 95% CI 0.29-1.00, P<.001) were also linked to increased symptom burden but lost statistical significance in model 3. Instead, lower self-efficacy (β=-0.39, 95% CI -0.54 to -0.23, P<.001) and higher somatosensory amplification (β=0.18, 95% CI 0.07-0.28, P=.001) were associated with a higher symptom burden. Compared with colder weather, light and moderate heat were associated with more severe health complaints. Symptom burden was lower in participants with higher self-efficacy and less somatosensory amplification. Self-reported protective behavior was not linked to a lower symptom burden. Instead, we found that patients who tended to catastrophize normal bodily sensations reported both better protective behavior and a higher symptom burden simultaneously. ClinicalTrials.gov NCT05961163; https://clinicaltrials.gov/ct2/show/NCT05961163.

Quantifying thermo-physiological stress exposure during extreme events: Developing a morphological case study in Istanbul

This study aimed to determine thermal comfort conditions during Extreme Heat Events (EHE), particularly focus on Very Hot Day and Heat Wave Event in Istanbul. The analysis was based on a comprehensive dataset of hourly temperature records collected from six meteorological stations over the period 1991–2021. Subsequently, Land Surface Temperature (LST) was mapped on the basis of EHE days. Finally, specific areas with different street morphologies values from the referenced LST were obtained, enabling the evaluation of heat stress for the EHE day and for the period between 2006 and 2021. The study identified August 5th, 2021 as the day of extreme heat stress in Istanbul. LST obtained for August 5th was divided into three groups: low (23.3°C), moderate (26°C), and high (29.3 - 30°C), and findings regarding heat stress were obtained through thermal indices. Physiologically Equivalent Temperature (PET) values on August 5th, 2021, were significantly higher than the 15-year average, showing a shift from moderate and slight heat stress to strong and extreme heat stress levels. PET values indicated strong heat stress, especially around noon, reaching up to 40.5°C in lower LST, and extreme heat stress level of 45.7°C in the afternoon in higher LST. Extreme thermal conditions were generally observed on the right side of streets oriented between 105° and 165° in both regions.

Experimental study on the low-temperature preheating performance of positive-temperature-coefficient heating film in the prismatic power battery module

The performance of a power battery directly affects the thermal safety performance of the vehicle. Aiming at the improvement of thermal safety of lithium-ion batteries under low temperature condition, this study focuses on the effect of the positive-temperature-coefficient (PTC) heating film on the heating performance of batteries through experimental testing. First, the side and bottom of the cell were heated, and the heat transfer path and mode of the single cell were analyzed. The effects of different power densities and geometric positions on the heating effect were studied by testing the heating time and temperature consistency. Second, for the battery module, a low-temperature heating thermal management heat transfer model was built to analyze the heating mechanism of the heating film under different heating power densities. Finally, the results of these studies were synthesized to obtain the optimal heating power density. The results show that for the cell, the optimum power density of side heating and bottom heating is 0.5 W /cm2 and 0.4 W /cm2, respectively. The time required for side heating from −20 °C to 10 °C is 730 s lower than that of bottom heating, and the maximum temperature difference is 1.885 °C lower. For battery modules, a power density of 0.5 W/cm2 was appropriate for both bottom and side heating methods. Due to the existence of heat conduction between battery packs, the battery modules will be quickly and evenly preheated. Under the optimal power density, the time length for side heating from –20 °C to 10 °C was 1459 s, and the maximum temperature difference was 6.32 °C; bottom heating time required slightly more time (1783 s), and the maximum temperature difference was 6.221 °C. Side heating can be beneficial for the rapid preheating of the battery module. This study will contribute to improving the performance and safety of batteries in cold environments.

Research on control strategy of electric vehicle thermal management system motor

Abstract The low efficiency and difficulty in low-temperature heating are the challenges currently faced by the thermal management system of new energy vehicles. A multi-heat source vehicle thermal management system for waste heat cascade recovery and utilization was proposed, and the performance of the vehicle thermal management system was studied through a combination of component testing and one-dimensional simulation. Based on a one-dimensional simulation model, the characteristics of the motor waste heat source are analyzed. The increase in the inlet water temperature of the motor coolant will lead to enhanced heat dissipation of the motor to the air, resulting in a waste of motor waste heat. Based on the results of the analysis, an energy cascade management strategy is constructed. The optimal heating mode is selected by collecting temperature signals such as motors, and the cut-off valve is controlled through logic gates to achieve flexible switching of different modes. The system effectively reduces the energy consumption of thermal management systems, which is of great significance for developing thermal management systems for new energy vehicles.

Methodology for determining the heat distribution in disc brakes of mine hoisting machines

Purpose. To study the course of heat phenomena in disc brakes using modern computing systems in order to determine and substantiate the operating parameters for the hoisting machine components. Methodology. The research uses software packages, with the help of which a computational-theoretical apparatus is developed for heat mode modeling processes. In particular, the mentioned function is used in the SolidWorks Simulation software with the ability to evaluate the errors of the calculation results. Findings. In the course of the research, the dependence of the hoisting machine disc brake performance on the operating parameters of its components was determined. The research has led to a better understanding of the heat transfer processes in disc braking devices, as well as the ability to study the friction response of various materials and determine optimal parameters that help improve the performance of braking systems. The effectiveness has been proven of the proposed method for analyzing the heat distribution processes of the mine hoisting machine drum components under the influence of operating and emergency braking modes. Originality. For the first time, a methodology for calculating the heating temperature distribution along the brake rim plane during a safety stop has been developed and substantiated. A method has also been developed for determining the temperature field arising under steady-state heating conditions, which occur after repeated operating braking and cooling of the device. In this case, when using the formula for determining the temperature on the brake rim surface, the sample length, the relative velocity between the friction components and the heat flow distribution coefficient are taken into account. The brake disc geometric model developed in the SolidWorks software package makes it possible to study the temperature change on the device rim in real time. Practical value. The proposed design improvement based on the research results of heating processes should improve vehicle safety. The cost of braking systems is expected to be reduced through the use of optimal materials and production technologies. The software methods for modeling and analyzing the temperature influence on brake discs of the Mine Hoisting Machine (MHM) have been improved. Based on the research results, recommendations have been developed for the optimum braking process of machines in various operating conditions.

A Durable Textile With Advanced Thermal Functions and Electromagnetic Shielding.

In the face of increasingly variable cold climates and diverse individual temperature regulation demands, personal thermal management (PTM) textiles with electromagnetic shielding have obtained significant attention. However, the PTM textiles face several challenges, including single heating mode, insufficient durability, and complex preparation processes. Herein, an all-day PTM textile Cotton@PDA/AgNPs (CPANS) with energy-free PRH, energy-saving solar heating, compensatory electricalheating, electromagnetic interference (EMI) shielding, and outstanding durability is fabricated by sequentially growing polydopamine (PDA) and silver nanoparticles (AgNPs) on the cotton fabric (CF). The CPANS exhibits low mid-infrared emissivity (36.6%) and high absorptivity (70.8%), which guarantees the energy-saving heating capability. Moreover, the conductivity of the CPANS is ≈11109Sm-1, enabling an electrical heating temperature of ≈177°C under a low voltage of 1.1V and superb EMI shielding effectiveness (≈60dB). The remarkable adhesive properties of the PDA ensure that the desired durability of the CPANS remains high even after rigorous physical treatments. This innovation shows enormous potential for wearable integrated garments in the future and offers a new ideal for PTM fabrics in the cold.

Testing the Efficiency of a Heat Pump with Radiant Systems in Heating Mode

The paper deals with the experimental testing of the efficiency of the operation of an air/water heat pump in connection with three radiant systems in heating mode in an office building, which is part of the central laboratories of the Slovak university of Technology in Bratislava. The testing was aimed at verifying the manufacturer's theoretical claims about efficiency of the heat pump based on the COP and SCOP values according to EN 14511-1:2022 and EN 14825:2022. The testing period was from 7 Jan. 2024 until 15 Jan. 2024. The aim of the testing measurements was to evaluate the calculated value of SPF efficiency for individual days and for the testing period. During the measuring period, the wall radiant system consumed 188 kWh, the ceiling system 216 kWh, and the floor radiant system 196 kWh. The heat pump consumed 227 kWh of electricity. The calculated SPF value was 2.64.

Research on intelligent control of fresh air introduction based on electric vehicle air conditioning system

The high power consumption of air conditioning systems is an important reason for the significant reduction in EVs (electric vehicles) range. Reducing its energy consumption has become an urgent industry problem to be solved. In order to reduce the energy consumption of the air conditioning system, this paper proposes an intelligent control strategy for the proportion of fresh air in the cabin of EVs, taking into account the impact of factors such as the number of passengers in the cabin, ambient temperature, and humidity on demand for fresh air, and analyzes the energy-saving effect of the intelligent control strategy through simulation. The analysis found that the minimum fresh air demand in the passenger compartment is greatly affected by the number of passengers in the cabin. The developed intelligent control strategy can significantly reduce the energy consumption of air conditioning systems. The energy-saving effect in northern China is significantly better than in southern China. The actual driving range of refrigeration and heating modes can be improved by 50 and 126 km, respectively.

Investigation of Engine Exhaust Heat Recovery Systems Utilizing Thermal Battery Technology

Over 50% of an engine’s energy dissipates via the exhaust and cooling systems, leading to considerable energy loss. Effectively harnessing the waste heat generated by the engine is a critical avenue for enhancing energy efficiency. Traditional exhaust heat recovery systems are limited to real-time recovery of exhaust heat primarily for engine warm-up and fail to fully optimize exhaust heat utilization. This paper introduces a novel exhaust heat recovery system leveraging thermal battery technology, which utilizes phase change materials for both heat storage and reutilization. This innovation significantly minimizes the engine’s cold start duration and provides necessary heating for the cabin during start-up. Dynamic models and thermal management system models were constructed. Parameter optimization and calculations for essential components were conducted, and the fidelity of the simulation model was confirmed through experiments conducted under idle warm-up conditions. Four distinct operational modes for engine warm-up are proposed, and strategies for transitioning between these heating modes are established. A simulation analysis was performed across four varying operational scenarios: WLTC, NEDC, 40 km/h, and 80 km/h. The results indicated that the thermal battery-based exhaust heat recovery system notably reduces warm-up time and fuel consumption. In comparison to the cold start mode, the constant speed condition at 40 km/h showcased the most significant reduction in warm-up time, achieving an impressive 22.52% saving; the highest cumulative fuel consumption reduction was observed at a constant speed of 80 km/h, totaling 24.7%. This study offers theoretical foundations for further exploration of thermal management systems in new energy vehicles that incorporate heat storage and reutilization strategies utilizing thermal batteries.

Coral reef community recovery trajectories vary by depth following a moderate heat stress event at Swains Island, American Samoa

Coral reef community recovery trajectories vary by depth following a moderate heat stress event at Swains Island, American Samoa

Theoretical analysis of heat and mass transfer characteristics of a counter-flow packing tower with different heating modes

Mass extraction/injection and multi-stage system have been proven to be effective approaches to improve the performance of humidification and dehumidification (HDH) desalination system. However, these two optimization schemes cause that the flow ratios of water to air at different positions of humidifier or that of different humidifiers have great difference. A single heating mode is inapplicable to all flow ratios of water to air. Hence, it is necessary to reveal the relationship among mass flow ratio, heating mode and thermal efficiency of humidifier for the selection of appropriate heating mode. A theoretical model of packing tower (typical kind of humidifier) which agrees well with experimental results was established in this paper, and the average relative errors of outlet air temperature, humidity and thermal efficiency are 2.3 %, 4.9 % and 5.8 %, respectively. A comparison among the thermal efficiencies of a counter-flow packing tower with different heating modes (I: solution heated, II: air heated, III: solution-air heated) was conducted. It is found that there exist two values of mass flow ratio (FRI-II and FRII-III) at which the thermal efficiencies of air heated and solution-air heated are equal and that of solution heated and solution-air heated are equal, respectively. However, the thermal efficiency of solution heated is always higher than that of solution-air heated (FRI-III does not exist). It seems clear that there is a relationship between FR and thermal efficiency (η) as follows: FR < FRI-II, ηI > ηIII > ηII; FRI-II < FR < FRII-III, ηI > ηII > ηIII; FR > FRI-II, ηII > ηI > ηIII. Additionally, the effects of inlet parameters on the FRI-II and FRII-III are also evaluated. The results show that the maximum temperature, inlet solution concentration and ambient temperature have positive effects on FRI-II and FRII-III, but ambient relative humidity has negative effect. In the final part, the selection of the heating mode of a counter-flow packing tower is taken as example to introduce the application of FRI-II and FRII-III proposed in this paper.

Performance study of solar air collector-air source heat pump system inside the greenhouse

During the process of heating greenhouses, the phenomenon of inadequate heating installations is widespread. To address this issue, this paper proposed a solar air collector-air source heat pump (SAC-ASHP) system for greenhouses, combining solar technology with heat pump (HP) technology to provide sufficient heat during continuous cloudy days and winter. The heating capacities of the system on sunny, cloudy, and overcast days were 100.2 kWh, 112.3 kWh, and 157.8 kWh, respectively. The corresponding power was 30.1 kWh, 36.1 kWh, and 53.6 kWh. The coefficient of performance (COP) of the single air source heat pump (ASHP) for these days was 3.4, 3.2, and 3.0, respectively, while the COP of the solar heat pump (SHP) was 4.0, 3.5, and 3.1. Additionally, greenhouse employed heat and moisture recovery for humid air, aiming to provide a suitable environment for plant growth around the clock while conserving energy. The heat collection in the heat and moisture recovery combined HP mode was 66.7 % higher than in the heat exchanger (HE)-fan mode. This experimental study investigated the operational performance of the system in dynamic environments, revealing the stability of the system for greenhouse heating in cold regions, and providing new research ideas for greenhouse heating.

Study of regularities and features of simultaneous contact interaction of active and inert metal melts with zirconia

ABSTRACT The mutual influence of interface processes during simultaneous contact of zirconia ceramic plate with adhesion-active Cu–Ga–Ti melt (on one side of the plate) and inert to oxides liquid copper (on other side of the plate) was studied. Wetting of ceramic with metal melts was studied by sessile drop method, the structure of the interfaces was determined using SEM. Due to the dissolution of ceramic oxygen in Cu–Ga–Ti, non-stoichiometric zirconia (ZrO2-x) is formed, then ‘surplus’ zirconium from the ZrO2-x structure dissolves in the copper melt, the stoichiometry of zirconia is restored and an additional amount of oxygen dissolves in the Cu–Ga–Ti melt. It leads to a decrease in the adhesion of Cu–Ga–Ti to ceramics, while improving the wetting of ZrO2 ceramics with copper. The ZrO2–Cu–Ga–Ti interface contains copper–titanium–oxygen intermetallides with zirconia inclusions, which does not provide adhesion of metals with solid oxides. If the contact of Cu–Ga–Ti with ZrO2 is formed before contact with liquid copper, then the interface layer contains oxidized titanium, which promotes adhesion of metal to ceramic. Thus, the design of the sample affects the processes in the studied systems in the same way as the heating mode and the amount of the active component.

Varying free-gas zone (FGZ) and bottom-simulating reflection (BSR) response across a deep graben off Trujillo, central Peru

The complexity of marine gas hydrate systems at the Peruvian convergent margin has been linked to the post-Miocene history of vertical tectonics and subduction erosion that affected the forearc. Here, multichannel seismic data and published findings reveal that such a complexity has been further extended by the occurrence of the pre-Miocene deep Morsa Norte Graben (MNG) off Trujillo (8°–9° S) in the Central Peru margin. At water depths of 650–750 m in the upper slope, directly above the MNG depocentre (which has a 4–6 km overburden thickness), continuous bottom-simulating reflections (BSRs) and concentrated sub-BSR high-amplitude reflections are confined beneath a layered basin with a low–moderate near-seafloor heat flow (7–33 mW m −2 ). A deeper BSR modelled with a thermogenic gas composition is associated with the enhanced reflections. At a water depth of 900 m, sub-BSR reflections become less frequent in an area with a layered sediment cover defined by a moderate near-seafloor heat flow (15–33 mW m −2 ). At a water depth of 1200 m, where the MNG is relatively thick (3–4 km overburden thickness), faults connect patchy BSRs with a moderate–high near-seafloor heat flow (52–110 mW m −2 ). There, sub-BSR enhanced reflections are scarce. Immediately above the top of the gas hydrate stability zone (GHSZ), the near-seafloor heat flow reaches 81 mW m −2 . Modelling suggests a water depth-dependent transport of heat towards the seafloor with respect to the top of the GHSZ, implying that the closer the seafloor is to the top of the GHSZ, the lower the advection of heat, and vice versa. Recent seafloor-related depositional and structural features amplify such relations in agreement with near-seafloor heat-flow variability. However, towards the area outside the extent of the MNG (&lt;3 km overburden thickness), continuous BSRs are not linked either to a deeper BSR or to sub-BSR enhanced reflections. The continuity of one of these BSRs is deflected upwards beneath a slump, suggesting an incomplete thermal re-equilibration of the GHSZ. Therefore, we conclude that the BSR responds to: (1) the confinement and thickening of the free-gas zone (FGZ) above the MNG depocentre due to the sealing effect of recent sedimentation close to the top of the GHSZ; (2) the seepage of gas-rich fluids from a thinned FGZ above the relatively thick MNG, due to the enabling effect of faults cutting the GHSZ far from the top of the GHSZ; (3) the undisturbed state of the FGZ outside the extent of the MNG; and (4) the disequilibrium state of the base of the GHSZ due to the unloading of sediments in an unstable slope environment prone to failure.

Adapting East and Southern Africa’s livestock to climate change: a decision making under deep uncertainty-based approach for effective actions

ABSTRACT Livestock farmers are increasingly challenged to adapt to the impacts of climate change, necessitating the selection of adaptation strategies to effectively mitigate risks and protect livelihoods. This paper introduces a framework designed specifically for guiding the selection of context-specific adaptation options in the Eastern and Southern Africa region. The framework builds on a decision tree that incorporates changes within a management system or switching to another one, enabling a nuanced evaluation of adaptation options. Driven repetitively under different scenarios of climate changes and/or climate models, the frequencies of selecting different adaptation measures vary across livestock value chains, climate zones, and systems. Responding to the evolution of the climate system, these frequencies evolve over time, affecting the selection. For instance, agroforestry emerges as an increasingly suitable option for cattle and, to a lesser extent, for goats due to the projected rise in moderate heat stress periods, particularly in tropical climates. Conversely, this frequency decreases for sheep, more susceptible to heat stress, beyond the effect of agroforestry. This framework resolves the need for more context – and time-specific decisions on adaptation. This decision tree-based framework serves as a robust decision-making tool to steer the livestock sector toward effective climate change adaptation.

Optimization of indoor thermal environment for high-altitude sentry buildings with attached ventilation based on proper orthogonal decomposition

The low-oxygen and severe cold climate characteristics of high-altitude regions significantly impact individuals' physiological health and thermal comfort inside buildings, especially for sentry buildings where the enclosure is fully exposed to the outdoors. This study aimed to optimize the indoor environment for high-altitude sentry buildings with attached ventilation. Firstly, the optimal location of exhaust outlets and oxygen sources in the heating mode of high-altitude sentry buildings was studied, and it showed high performance in terms of thermal comfort and energy efficiency. Additionally, the POD method and interpolation methods were applied to expand the sample dataset and identify the optimal combination of attached ventilation parameters and oxygen supply concentration, creating a comfortable, oxygen-enriched environment within the sentry buildings while also considering energy efficiency. The results indicate that when the optimization objective is weighted towards thermal comfort, the percentage of dissatisfied (PD) and the draught rate (DR) values under the optimal scheme are reduced by 82 % and 46.6 %, respectively, compared to previous studies. However, when the emphasis is on energy efficiency in environmental optimization, the air supply energy under the optimal scheme has a 64.4 % reduction compared to previous research results. When considering both optimization objectives simultaneously, the PD and DR values under the optimal scheme are reduced by 35.9 % and 96.9 %, respectively, compared to previous research results. These results demonstrate significant improvements in both thermal comfort and energy efficiency relative to our previous study.

Hourly electricity CO[formula omitted] intensity profiles based on the real operation of large-scale natural gas combined cycle cogeneration plants

The decarbonization of energy systems is a major challenge that requires complex cross-sectoral strategies that need to be supported by energy modeling. As many technologies rely on electricity, an accurate estimation of its CO2 intensity is of utmost importance for the reliability of modeling results. When electricity is generated from fossil sources, its CO2 intensity depends on several parameters. This research paper presents an hourly calculation of the CO2 intensity of power generation from natural gas combined cycles, based on real data from several years of operation of three plants. As these plants are also operated in combined heat and power mode, two alternative allocation methods are compared. The results confirm the variability of CO2 intensity based on the different operation strategies of the plants and the share of heat and electricity generated. The hourly analysis shows average values in the range of 230–250 gCO2/kWh in winter, rising to around 330–370 gCO2/kWh in summer. The real CO2 intensity profiles presented in this paper can be integrated into energy planning models to improve their ability to estimate the potential benefits of different decarbonization solutions by including the effect of the operational profiles over the day and the year.