Heating Device Research Articles

Study on the Effect of Local Heating Devices on Human Thermal Comfort in Low-Temperature Built Environment

Localized heating systems are an effective approach to improve thermal comfort while reducing energy consumption in a cold indoor environment. Furthermore, localized heating devices have found widespread application in the hot-summer and cold-winter zones of China. This study investigates the heating characteristics of the local heating device in a low-temperature environment, as well as its effects on subjective perception and physiological responses, and develops a personalized control system for the device based on the experimental findings. We conducted experimental tests and questionnaires in a test room with air temperature set at 12 °C and 14 °C and a relative humidity of 55%. A total of six experimental conditions were designed using five types of heating equipment (heating wrist straps, heating insoles, heating leg straps, warm air blower, electric radiant heater), each employing different heat transfer methods. The results demonstrate that the head, hands, legs, and feet are susceptible to feeling cold in a low-temperature environment, and the use of a warm air blower and electric radiant heater can significantly enhance the thermal sensation of these parts, improve thermal acceptability, and raise local skin temperature. The electrocardiogram data indicate that heart rate variability can be utilized to assess thermal sensation in a cold environment with localized heating. Additionally, the relationship between thermal response and skin temperature was investigated, leading to the development of a control strategy for the local heating device in a low-temperature conditions.

An Experimental Study on the Heat Transfer and Flow Characteristics of Aluminum Heating Elements Coated with Graphene

With the rapid development of clean heating, electric heating has received increasing attention. As a common electric heating device, heaters are also widely used in residential and industrial heating, as well as in other fields. In order to improve the reliability and heat transfer flow characteristics of the electric heating element of the heater, a new type of structural electric heating element was designed and developed based on the surface heat transfer enhancement and pit drag reduction characteristics of graphene. The heat transfer and flow characteristics of the electric heating element were analyzed through experiments, and the results showed that the average surface emissivity increases from 0.25 with the non-graphene-coated sample to 0.94 with the graphene-coated one, and the surface temperature of the electric heating element decreased from 289 °C to 237.5 °C. Through wind-tunnel experiments, it was found that the PEC value of the electric heating element with pits was 1.0693, and the Nusselt number increased by 6.22% compared with the smooth surface. Furthermore, after coating with graphene, the Nusselt number increased by 30.3% compared with the smooth surface.

Analysis of an Electronic Heating Device: System Modeling, Identification and Control

Analysis of an Electronic Heating Device: System Modeling, Identification and Control

A quadrupole-based approach for integrated building simulation and energy-efficient load control

This paper is an extension of our previous work in which an exact analytical method was used to model the transient heat transfer behavior in buildings. The method concerns a quadrupole-based approach (QD), where a general equation is set for each zone's heat balance to obtain either temperature or heat rates. The proposed model proved its ability to accurately account for indoor thermal masses with short computation time. In this work, we are aiming to further validate the ability of the quadrupole-based method to model such combined effects as thermal mass, direct solar gain windows, internally generated heat, infiltration, and more particularly, setback thermostat control, with heating and cooling control inside a single zone by developing a convenient algorithm. For this, two reference cases from the Building Energy Simulation Test (BESTEST), reported in ANSI/ASHRAE standard 140, are selected: the 640 case (light-weighted materials) and 940 case (heavy-weighted materials). Results of the simulations in terms of annual energy demand as well as power peaks have been compared between the QD-based algorithm and other whole building simulation programs. For a more accurate analysis, results of our developed algorithm have been compared to those issued from EnergyPlus (EP) alone, in reference to the BESTEST methodology, by generating monthly energy demand, power peaks as well as annual energy demands. Indeed, some discrepancies have been noticed since both models use different algorithms. However, our model has been successfully validated by the BESTEST methodology and proved its efficiency in terms of defining the required exact power that needs to be deployed. In addition to this, the algorithm can be immediately used in real physical control regardless of the type of heating device.

Analysis of OLED glass substrate heated by heating tube array based on multiple optimization algorithms

The temperature uniformity of OLED glass substrate during heat treatment is a key factor affecting the quality of its imaging display. This paper constructs the heating process model of OLED glass substrate based on heating tube array according to the actual scene, studies the thermal characteristics of OLED glass substrate, and then optimizes the temperature uniformity of glass substrate under isometric heating mode based on genetic algorithm, particle swarm optimization algorithm and simulated annealing algorithm. Compared with the initial solution of the algorithm, the optimization rates of the three algorithms respectively reach 75.5%, 86.4% and 98.3%, and the temperature differences are reduced to 3.82℃, 1.44℃ and 0.30℃. Finally, an experimental platform is built to verify the optimization results of different algorithms. The absolute errors are 0.58℃, 1.46℃, 1.30℃ respectively, all lower than 1.5℃, which is within the allowable range of process requirements. It is proved that the proposed optimization algorithm control mode can reduce the heating temperature difference of glass substrate to the ideal level based on the heating device with low cost and simple structure. This scheme provides some reference for the formulation of temperature distribution solution in heat pipe heating technology.

Research on Shape-Controllable Localized Heating Method Driven by Digital Microfluidics.

The localized heating technique, which minimizes high-temperature impact on thermally sensitive components and reduces impurity dispersion during encapsulation, has become a focal point in MEMS packaging research. In this study, we propose a method for localized heating at specific positions and shapes. A localized heating device, based on distributed electric field control, is constructed, where a polymer droplet on the lower substrate electrode is driven into a liquid column under the influence of a distributed electric field generated between two parallel substrate electrodes. ITO substrate electrodes with various patterns are fabricated, ensuring the shape of the formed liquid column matches the pattern. Leveraging the principles of heat transfer, the temperature of the polymer droplet is regulated via a heating stage to enable targeted heating of defined shapes and areas. Experiments delve into the impact of driving parameters on heating time and efficiency, with results affirming the proposed method's capability to govern localized heating for particular regions and configurations accurately.

Resilient energy management of a multi-energy building under low-temperature district heating: A deep reinforcement learning approach

The corrective control of a building-level multi-energy system (MES) for emergency load shedding is essential to optimize the operating cost after contingency. For a Danish case, the heating devices in the building are connected to a developing low-temperature district heating (LTDH) system and operated under a heat market. Due to the coupling between the electrical power and heating system, an electricity outage can be propagated to the heating network, and heat prices as well as tariffs can impact the MES operating cost. In the previous studies, only electrical load shedding is modeled, while the impact of electricity outages on heating system operation and heat load control is ignored. On the other hand, the problem is traditionally solved by model-based optimization methods which are highly nonconvex leading to high computing complexity. Moreover, operating uncertainties can lead to infeasible solutions. To address these challenges, this paper proposes a deep reinforcement learning-based corrective control method for the resilient energy management of a building-level MES. In the method, the proximal policy optimization algorithm is applied, where multiple uncertainties, system dynamics, and operating constraints are considered. A case study of a real-life residential building connected to the LTDH system in Denmark is carried out, where electricity outages are simulated. The results verify the performance of the proposed method in achieving resilient energy management of the MES.

Cr-free Refractories for Copper Metallurgy: Raw Materials and Factsage Thermodynamic Simulations

The copper industry continuously uses great amounts of Cr-containing refractories, which are installed in all heating devices, despite their known negative environmental impact. The development of alternative materials seems feasible via replacing chromite spinel with other Cr-free spinel, using magnesia or alumina as a dominant component in the composition of new refractory. In light of the longstanding issue, the article presents the properties of key refractory raw materials (magnesia and alumina) and potential Cr-free spinels which can be combined to emerge a new generation of refractories dedicated to the copper industry. Subsequently, the results of FactSage corrosion simulations were revealed for Cr-refractories and seven Cr-free magnesia refractories containing spinels of different chemistry against industrial copper converter slag with Fe/SiO2 of 2.5. Through tracking the changes in solid and liquid phases appearing during interactions in a range of 1100-1400oC as well as liquid viscosity alterations the most prospective solutions have emerged by referring their properties to commercial MgO-Cr2O3 refractory.

Bacterial Adhesion and In Situ Biodegradation of Preheated Resin Composite Used as a Luting Agent for Indirect Restorations.

To evaluate surface roughness and bacterial adhesion after in situ biodegradation of the cementation interface of indirect restorations cemented with preheated resin composite. Resin composite blocks (Z250XT/3M ESPE) were cemented to bovine enamel (7 × 2.5 × 2 mm) using preheated microhybrid resin composites: (1) Filtek Z100 (3M ESPE) (Z100); (2) Gradia Direct X (GC America) (GDX); and (3) Light-cured resin cement RelyX Veneer (3M ESPE) (RXV) (n=21). The resin composites were preheated on a heating device (HotSet, Technolife) at 69°C for 30 minutes. Disk-shaped specimens (7 × 1.5 mm) were made for biodegradation analysis with the luting agents (n=25). The in situ phase consisted of 20 volunteers' using an intraoral palatal device for 7 days. Each device had six cylindrical wells for the blocks and the disk-shaped specimens. Biodegradation was evaluated through surface roughness (Ra), scanning electron microscopy (SEM) micromorphological analysis, and colony-forming unit (CFU) count. The film thickness of the luting agents was also measured under stereomicroscopy. Increased surface roughness was observed after the cariogenic challenge without differences between the luting agents. Higher variation and surface flaws suggestive of particulate detachment were observed for Z100. No differences were observed in CFU counts. All materials underwent surface biodegradation, and the surface roughness of the resin cements was similar to or lower than that of the preheated resin composites. The resin composites' film thickness was thicker than that of the resin cement. Clinicians should be aware of these factors when choosing the use of preheated resin composite since it can lead to reduced longevity of the cementation interface and, therefore, restorations.

Comparing the improvement of occupant thermal comfort with local heating devices in cold environments

Local heating can improve the thermal comfort of occupants and save energy in buildings in cold environments; however, few studies have investigated the effects of heat-transfer modes. Here, we aimed to evaluate different local heating measurements including five-sided enclosed radiant panel, heating plate, and fan heater using climate chamber experiments with 20 participants in cold environments (14 °C). Skin temperature and thermal perception votes under two radiation types with low and high power, one condition of conduction, and one condition of convection were collected and analyzed (RL, RH, CD, and CV). Under conditions RH, CD, and CV, the investigated parameters significantly improved by three local heating devices, with foot skin temperature rising by 0.46 °C, foot thermal sensation rising by 1.25 scores, and overall thermal comfort increasing by 0.36 score; however, their energy consumption varied greatly. In contrast, no significant improvement was observed in the RL group. Additionally, direct application of heat at sites of palpable cold discomfort was not always the optimal approach, and heating other parts of the body may provide significant alleviation. We recommend that the surface temperature of local heaters based on conduction and radiation for heat transfer should not be lower than 40.38 °C and 52.15 °C, respectively. To maintain thermal comfort, air outlet temperature should not be lower than 34.56 °C for convection type heaters. Our results provide technical and experimental basis for designing energy-saving buildings.

Imitation learning with artificial neural networks for demand response with a heuristic control approach for heat pumps

The flexibility of electrical heating devices can help address the issues arising from the growing presence of unpredictable renewable energy sources in the energy system. In particular, heat pumps offer an effective solution by employing smart control methods that adjust the heat pump’s power output in reaction to demand response signals. This paper combines imitation learning based on an artificial neural network with an intelligent control approach for heat pumps. We train the model using the output data of an optimization problem to determine the optimal operation schedule of a heat pump. The objective is to minimize the electricity cost with a time-variable electricity tariff while keeping the building temperature within acceptable boundaries. We evaluate our developed novel method, PSC-ANN, on various multi-family buildings with differing insulation levels that utilize an underfloor heating system as thermal storage. The results show that PSC-ANN outperforms a positively evaluated intelligent control approach from the literature and a conventional control approach. Further, our experiments reveal that a trained imitation learning model for a specific building is also applicable to other similar buildings without the need to train it again with new data. Our developed approach also reduces the execution time compared to optimally solving the corresponding optimization problem. PSC-ANN can be integrated into multiple buildings, enabling them to better utilize renewable energy sources by adjusting their electricity consumption in response to volatile external signals.

Coordinated price-based control of modulating heat pumps for practical demand response and peak shaving in building clusters

With a high share of renewable energy in the power grid, it becomes increasingly difficult to ensure a continuous balance between power generation and consumption, thereby endangering grid stability. A substantial opportunity to address this challenge and align the heating demand with intermittent power production is offered by space heating and domestic hot water, which account for 80% of the energy consumption in buildings. Further research on the control of building clusters is required, where peak load management of multiple buildings can ensure grid stability during peak hours and contribute to avoiding power outages. In this paper, a rule-based controller is presented, called Extended Price Storage Control+ (EPSC+), for the practical and flexible operation of heating systems in a building cluster. Under dynamic pricing, the loads of electric heating devices for the provision of space heating and domestic hot water are shifted by EPSC+ while accounting for peak load constraints. The performance of EPSC+ is evaluated in a nine-week winter simulation study with a building cluster of ten buildings in Germany. For comparison, a hierarchical model predictive controller (MPC) and a hysteresis two-point controller are employed as benchmarks. Results close to those of MPC are achieved by EPSC+by reducing the median peak load by 38.8% and median electricity costs by 15% compared with the hysteresis controller. In contrast to MPC, EPSC+ does not require models, forecasts, or optimization and is computationally inexpensive, rendering it more attainable for real-world implementation.

The Benefits of Silicone Laryngectomy Tubes at the Time of Laryngectomy-A Case Series Spanning 17 Years.

Although total laryngectomy (TL) is a well-established surgical procedure with clear functional or oncologic indications, the peri- and postoperative care for those undergoing TL is variable, particularly regarding postlaryngectomy tracheostoma management. This study examined TL outcomes from a single institution with the immediate perioperative use of soft silicone laryngectomy tubes. More specifically, we explored potential complications associated with immediate perioperative use of a flexible laryngectomy tube (LaryTube and StomaSoft) and the use of heat and moisture exchange (HME) devices in association with peri- and postoperative care. A case series including all patients undergoing TL by one primary surgeon at a tertiary care hospital between 2006 and 2023 were assessed. Variables of interest included hospital average length of stay (LOS) in hospital, use of laryngectomy tube and an HME, primary tracheoesophageal puncture voice restoration at time of TL, discharge feeding, stoma-related complications, and overall complications. Seventy-two patients were included over the study period, and all utilized a laryngectomy tube and HME in the perioperative period without complications. Fifty-six patients (77.7%) had concurrent neck dissections and nine (15%) underwent total laryngopharyngectomy. Sixty-two patients (86%) underwent TL for squamous cell carcinoma of the larynx or hypopharynx and 35 of these (56%) were salvage surgeries. Mean LOS was 8.4 (3-45) days, and 63 patients (88%) were discharged with nasal gastric tube feeding. Of the six patients (8%) who were readmitted for complications, zero (0%) were related to the laryngectomy tube or to stoma-related complications (e.g., dehiscence, infection, mucous plugging). No patient who utilized a laryngectomy tube and HME device in the perioperative period experienced stomal stenosis. Laryngectomy tubes combined with an HME can be employed safely and successfully in a high percentage of laryngectomy patients placed perioperative. No instances of postlaryngectomy tracheostoma stenosis occurred in association with perioperative laryngectomy tube with HME use. These collective data support the use of a laryngectomy tube with HME in the immediate perioperative period, with low risk of complications.

Thermal Performance Investigation of Vapor Chamber Under Partial Heating and Different Heat Flux Conditions: Effects of Inclination Angle

Abstract The need for cooling technologies increases tremendously with raising demand on the powerful and compact electronics. There, it pushes the research and technology to the new investigations on varying heat transfer mechanisms and devices. While one of these devices is vapor chamber (VC), an experimental study has been carried out to investigate the heat transfer performance of a VC under partial heating, varying heat fluxes, and different inclination angles for different temperatures, in the current study. For this purpose, a VC with a dimension of 90 mm × 90 mm × 3 mm is evaluated via its resulting thermal resistance, performance, and the temperature distribution over the VC surface. There, the limited effect of inclination angle is observed on the performance, while the highest change is obtained with decreasing local heating surface area, thus increasing heat fluxes. Moreover, this trend is seen almost similar with a reasonable shift up or down according to the different temperature differences.

Implementation of Regenerative Thermal Oxidation Device Based on High-Heating Device for Low-Emission Combustion

In this paper, a heating device is implemented by considering two large factors in a 100 cmm RTO design. First, when the combustion chamber is used for a long time with a high temperature of 750–1100 °C depending on the high concentration VOC gas capacity, there is a problem that the combustion chamber explodes or the function of the rotary is stopped due to the fatigue and load of the device. To prevent this, the 100 cmm RTO design with a changed rotary position is improved. Second, an RTO design with a high-heating element is implemented to combust VOC gas discharged from the duct at a stable temperature. Through this, low-emission combustion emissions and energy consumption are reduced. By implementing a high heat generation device, the heat storage combustion oxidation function is improved through the preservation of renewable heat. Over 177 h of demonstration time, we improved the function of 100 cm by discharging 99% of VOC’s removal efficiency, 95.78% of waste heat recovery rate, 21.95% of fuel consumption, and 3.9 ppm of nitrogen oxide concentration.

THE IMPACT OF SOLAR RADIATION ON THE TEMPERATURE REGIME OF A ROOM IN WINTER

The article is devoted to the computational studies of the air-thermal state of office premises taking into account the effect of solar radiation coming through window openings. The study was conducted for a room with two windows using two heating devices installed under them. The air-temperature regime of premises in winter, characterized by the highest thermal energy consumption for heat supply, is considered. The study is based on the solution of a three-dimensional nonlinear heat transfer problem described by a system of equations of turbulent momentum and energy transfer. The k-e turbulence model is used to close this system. The results of numarical modeling of the physical situation under study are presented. The research data on the features of the air-thermal state of the premises under solar radiation conditions are given. The results of a comparative analysis of the air-temperature conditions of office premises corresponding to the solution of the specified heat exchange problems in the presence and absence of solar radiation are presented and the effects of solar radiation on the structure of the air flow and the thermal state of the premises are established. It is shown that in the presence of solar radiation, the air flow picture and the character of the temperature fields in the premises change significantly. In particular, in these conditions, the increase in the average temperature of the premises for the studied period is 2.5 °С. The possibility of a certain reduction of the load on the heating system in the presence of solar radiation is noted. Bibl. 17, Fig. 5.

Scenario-based stochastic optimization on the variability of solar and wind for component sizing of integrated energy systems

The inherent intermittency and variability of renewable energy sources present significant challenges to the optimal design and implementation of integrated energy systems (IES). This paper introduces a novel stochastic optimization model that integrates advanced scenario generation and clustering algorithm for renewable energy sources within a multi-objective, bi-level optimization framework. Specifically, the clearness index is employed to represent the stochastic distribution of solar radiation intensity by beta distribution, while wind speed uncertainty is modeled seasonally using the Weibull distribution. Monte Carlo sampling with synchronous back substitution is applied for scenario generation and reduction of solar radiation and wind speed. To address the multi-objective evaluation, the analytic hierarchy process is utilized, and the joint optimization is achieved by combining a region contraction algorithm with stochastic programming. The proposed methodology is validated on an IES featuring various heating devices, incorporating uncertainties in both wind and solar energy. The results indicate that the absorption heat pump-based scheme achieves superior energy-saving performance, achieving an energy rate of 0.4724. Additionally, the compression heat pump-based scheme exhibits excellent economic efficiency and environmental sustainability, with a cost of energy of 0.3639 and a renewable fraction of 0.5536.

B-224 Rapid, Extraction-Free, and Portable Molecular Detection of HIV-1 and HCV Directly From Whole Blood

Abstract Background Early diagnosis of human immunodeficiency virus-1 (HIV-1) and hepatitis C virus (HCV) is key to preventing viral transmission and improving linkage to treatment. Isothermal amplification methods, such as reverse transcription looped-mediated amplification (RT-LAMP), have enabled molecular diagnostics to expand beyond centralized laboratories. Despite the advances in molecular point-of-care (POC) testing, many of these tests are costly and still depend on a reliable power-source, specialized equipment, and cold-chain storage, making them impractical for resource-limited settings. To overcome these barriers, there is a need for innovative molecular diagnostics for blood-borne pathogens. Here, we propose a simple, extraction-free, portable workflow for detecting HIV-1 and HCV from whole blood within 40 minutes. Methods We developed singleplex RT-LAMP-based tests using modified published primer sets. Contrived whole blood samples containing HIV-1 or HCV virions were diluted in equal parts water and loaded directly into optimized RT-LAMP master mixes. To mitigate cold-chain storage dependence, RT-LAMP reactions were performed using a lyophilized master mix. The reactions were heated for 30 minutes using a hand-held, battery-powered heating device for simultaneous virion lysis and amplification. For simple visual detection, amplification was coupled with a lateral flow-based dipstick test. The analytical sensitivity of each detection test was evaluated using contrived whole blood samples ranging in HIV-1 and HCV 1a viral loads. Additionally, HCV detection was evaluated on genotypes 1b, 2b, and 3a. For result confirmation, a custom CRISPR-Cas12a-based assay was used to verify the presence or absence of pathogen-specific amplicons following amplification. Results The diagnostic workflow can be completed within 40 minutes, including less than 10 minutes of hands-on time. At optimal conditions, the HIV-1 and HCV 1a singleplex tests had lower limits of detections of 4.89 log10 cp/mL and 3.77 log10 IU/mL, respectively. Evaluation of the published literature showed that these viral loads are within the ranges observed during acute HIV-1 and HCV infection. HCV detection was also observed for genotypes 1b and 3a, albeit at a lower sensitivity than genotype 1a. No detection was observed for genotype 2b, presumably due to the lower viral loads of the samples. No cross-reactivity between the two tests was observed. Conclusions Our proposed workflow allows for rapid detection of blood-borne pathogens without the need for complex equipment or cold-chain storage, showing potential for application in resource-limited settings. Additional validation within a clinical setting using fingerstick blood remains to be tested.

Відтворення слов’янського побуту шляхом натурного моделювання

The article is dedicated to one of the most promising directions in archaeological research – experimental archaeology. It outlines the significance of experimentation in modern archaeology in Ukraine and the world, explores the historiography of the problem, and shares the experience of archaeologist colleagues in reconstructing certain aspects of the lives and everyday activities of past generations. Key aspects of experimental archaeology include the creation of replicas or reconstructions to test hypotheses and enhance understanding of ancient objects and technologies. Furthermore, it underlines the practical meaning of experimental archaeology, such as the creation of open-air museums, which provide immersive experiences and contribute to the preservation and dissemination of cultural heritage. The Northern Permanently Operating Archaeological Expedition of the Institute of Archaeology of the National Academy of Sciences of Ukraine is engaged in the scientific and scientific and protective direction of studying the suburbs of Kyiv. Research mainly concerns the ancient Rus period. The recreation of ancient Rus technologies through their full-scale modeling is not new for the employees of the expedition. Based on this, at the territory of the Khodosivka archaeological complex, models of Early Slavonic ovens were recreated as a source of knowledge about the everyday life of medieval society in Ukraine. The paper provides a detailed description of the construction of models of two heating devices, prototypes of which are dated mainly from the 12th to the first half of the 13th century. All stages of their creation are characterized: from studying general information about the ovens and planning the future reconstruction, to processing the collected data and implementing the experiment. Based on the modeling of these experiments, the functional capabilities of the reconstructed ovens are revealed. The significance of the conducted experiment lies in its ability to deepen our understanding of the daily life of the Kyivan Rus population. While previous research focused on technologies used in creating various economic and residential structures, this work demonstrates how reconstructed models aid in delving into the study of ancient domesticity. Since the chronicle tradition does not cover all aspects of ancient society’s life, and archaeological evidence alone does not provide a precise picture of the population’s spiritual and everyday life, this experiment allows for a more detailed exploration of these aspects. Key words: experiment, modeling, skansen, oven, heating device, Ancient Rus, Khodosivka.

Lightweight 3D-printed heaters: design and applicative versatility

This paper proposes a new strategy for designing a 3D-printed heater that can overcome some criticalities of current commercial heater devices for application in the transport and energy sectors. A semiconductive nanocomposite material, acrylonitrile-butadiene-styrene filled with carbon nanotubes (ABS-CNT), was processed via Fused Filaments Fabrication (FFF). The printing was set to favor the current flow along the printing direction, consequently increasing the material's electrical conductivity. 3D-printed heater geometry, equivalent to several electrical resistances (resistive branches) connected in parallel, was optimized by varying the width, thickness, lengths, and number of branches. The adopted approach resulted in a flexible and scalable low-equivalent resistance value heater. Moreover, the optimized heater's flexibility allows it to be integrated into a curved fiberglass composite. Joule heating tests were experimentally performed and theoretically simulated by a multi-physics model. The numerical prediction resulted in good agreement with the experimental data. The results encourage the application of 3D-printed heaters as functional patches for the thermal management of different devices/components, including complex-shape composite structures.