Reduction Of Heat Load Research Articles

Effect of Photovoltaic Energy-Saving Window Factors on Building Heating Load Under Three Control Modes

Photovoltaic (PV) glazing is widely used in the building sector for its power generation advantages. However, its low transmittance reduces solar heat gain, limiting energy-saving effectiveness in heating regions. To address this, the present study proposes a novel PV energy-saving window that reduces heating load by separately controlling its components—PV glazing, insulated shutter, and clear glazing—through three control modes: Mode 1 controls insulated shutter, Mode 2 controls insulated shutter and PV glazing, and Mode 3 controls insulated shutter and clear glazing. First, the energy-saving benefits of the window were confirmed through in situ testing. Next, using a validated model, the correlation between key factors and heating load was analyzed under the above three modes. Finally, the impact of configurations on heating load under the three control modes was clarified. The main findings are as follows: (1) When PV glazing is controlled, clear glazing layers become the primary factor influencing the heating load. (2) In Modes 1 and 3, the configurations have a greater impact on heating load, reducing it by 34.62% and 39.60%, respectively, while Mode 2 shows a reduction of 17.93%. (3) Mode 2 is the optimal control mode, confirming the effectiveness of controlling PV glazing to reduce heating load.

Reducing heat load density with asymmetric andinclined double-crystal monochromators: principles and requirements revisited.

xxxx Asymmetric double-crystal monochromators (aDCMs) and inclined DCMs (iDCMs) can significantly expand the X-ray beam footprint and consequently reduce the heat load density and gradient. Based on rigorous dynamical theory calculations, the major principles and properties of aDCMs and iDCMs are presented to guide their design and development, particularly for fourth-generation synchrotrons. In addition to the large beam footprint, aDCMs have very large bandwidths (up to ∼10 eV) and angular acceptance, but the narrow angular acceptance of the second crystal requires precise control of the relative orientations and strains. Based on Fourier coupled-wave diffraction theory calculations, it is rigorously proved that the iDCM has almost the same properties as the conventional symmetric DCM, including the efficiency, angular acceptance, bandwidth, tuning energy range and sensitivity to misalignment. The exception is that, for the extremely inclined geometry that can achieve very large footprint expansion, the iDCM has (beneficially) a larger bandwidth and wider angular acceptance. Inclined diffraction has the `rho-kick effect' that can be cancelled by the second reflection of the iDCM (even with misalignment), except that inhomogeneous strains may cause non-uniform rho-kick angles. At present, fabrication/mounting-induced strains pose low risk since they can be controlled to <0.5 µrad over large areas. The only uncertain challenge is the thermally induced strains, yet it is estimated that these strains are naturally lowered by the large footprint and may be further mitigated by optimized cryogenic cooling to the 1-2 µrad level. Overall, aDCMs and iDCMs have more stringent requirements than normal DCMs, but they are feasible schemes inpractice.

PARAMETERS OF HOT WATER SUPPLY HEAT EXCHANGERS FOR HEAT STATIONS OF INSULATED BUILDINGS AT ONE-STAGE CONNECTION SCHEME

The peculiarities of functioning of centralized heat supply systems of residential microdistricts at carrying out works on ‘insulation’ of buildings in operation, namely, parameters of operation of hot water supply heating units are considered. The influence of the heating load reduction due to the works on increasing the heat transfer resistance of the building structures on the flow rate of network water and heat exchange area of hot water supply heaters has been analyzed. Estimates are made for conditions of use of one-stage parallel scheme connection for heat exchangers to heat distribution networks. The known relations for such most widespread in heat supply systems heat exchangers as plate apparatuses are used at calculations of a heat transfer surface. The range of change of the heat transfer surface of hot water heaters and the flow rate of network water depending on the ratio of the maximum heat loads of hot water supply and heating and the degree of insulation efficiency of the building is determined. Formulas for determining the parameters of hot water supply heat exchangers are proposed. The formulas are valid in the range of reduction of heat consumption for heating of the building from 0 to 35 %. Assessment of the heating load reduction is performed on condition that the thermal modernization of a building constructed in accordance with the building requirements in force several decades ago provides modern requirements for the thermal resistance of building structures. The temperature of water in the heating system of the insulated building is determined depending on the building insulation efficiency, provided that the water flow rate through the heating system of the building before and after its insulation is unchanged. The range of variation of the ratio of hot water supply and heating heat loads accepted for consideration is 0,6–1,2. The obtained results can be used at comparison of connection schemes of heat exchangers for hot water heating for installation on individual heat points of insulated buildings.

Thermal Protection Analysis of Hypersonic Reentry Nose Cone with Multi-Row Disk Spike Using Lateral Single/Multi Jets: A Computational Investigation

Abstract This research examines the efficacy of employing lateral multi jets to decrease thermal effects on the blunt body featuring a multi-row disk spike, which holds significant importance in the design of high-speed vehicles. The main novelty of the model is the combination of the spike with Multiple row disk along with the injection of the coolant jet. The study thoroughly analyzes the cooling mechanism of lateral jets and assesses the influence of coolant jet positioning on heat reduction of the nose and mechanical spike. This study employed RANS equations with SST turbulence model for the simulation of the high-speed flow around the nose cone with Multi-Row Disk Spike. A comparison is made between the effectiveness of CO2 and helium jets, both as single and multiple injectors. The results display that a single CO2 jet released near the tip of the spike is the most effective, and placing the lateral coolant injector away from the main body effectively manages aerodynamic heating. Additionally, the research compares the heat load reduction achieved by triple lateral jets and concludes that the CO2 jet is the most efficient option for thermal protection of the main body. The role of the spike in reduction of the heat load is reduced 20% when CO2 jet is released from all lateral injectors.

Comprehensive analysis of thermal performance and low-grade energy charging efficiency of pipe-embedded building envelopes enhanced with single-level tree-shaped fin structures

Pipe-embedded walls (CnPWs) are structural and energy composite building components that can resist external disturbances by forming stealth thermal shielding layers. To tackle the mismatch between the heat charging rate and heat diffusion rate during energy charging processes, as well as the unsatisfactory robustness of stealth thermal shielding layers, the single-level tree-shaped metal finnd pipe-embedded walls (TfPWs) are proposed. To verify the effectiveness of TfPWs and obtain dynamic performances, a simulation study is conducted on 8 risk variables in 4 pairs through the validated numerical model. Results showed that the improved design was effective in obtaining more robust thermal shielding layers in auxiliary energy supply mode, the effect gained prominence as both the injection temperature and pipe spacing were augmented. In room heat load reduction mode, favorable benefits arise when pipe spacing exceeds 400 mm. The maximum increase rate of total injected energy under different reduction ratios of external insulation layer was 11.83%–31.91 %, while the maximum extra total heat loss was 5.33 %. Secondly, the trunk fins and branch fins played different roles in minimizing the excessive heat accumulation surrounding pipes, and the vertical and horizontal sizes of heat accumulation region mainly increased with the increase in trunk fin size and branch fin size respectively. Meanwhile, the utilization efficiency of fin material was higher when trunk fin size was smaller, and parameter combinations with trunk fin size of 0.2b and branch fin size of 0.4a/0.6a could achieve a better balance between material input and performance increase. Thirdly, the improvement effect of single left branch fin schemes was close to that of double branch fin schemes and significantly better than that of single right branch fin schemes. It was recommended to use single left branch fin schemes with an inclination angle of 60°. Finally, even if the reduction ratio of external insulation layer in different cities increased to 80 %, the inside surface temperature of TfPWs was still greater than room air. Taking CnPWs with standard external insulation layer as references, the TfPWs applied in Harbin, Beijing, and Shanghai could achieve similar or better results even when the reduction ratio of external insulation layer increased to 60 %, while TfPWs applied in Guangzhou could exhibit better performance even when the reduction ratio of external insulation layer increases to 80 %.

Potential of thermal protection improvements in large-scale cryostat development

Tremendous efforts are being pursued by experimentalists worldwide in the designing of cryostats to minimize the most dominant radiation heat load over the cryogenic liquid kept inside it. These endeavors are imperative to secure the safe, consistent, and reliable performance of detectors, notably for experiments delving into the investigation of rare physics events, particularly those moving towards ton-scale capacities. In these experiments, maintaining a stable temperature of the cryogenic liquid is crucial. This stability helps in minimizing thermal noise and reducing the loss of cryogenic liquid by mitigating its evaporation rate, and this can be accomplished by reducing the ambient heat load coming from the outer hot wall towards the inner cold wall of the cryostat. Current work scrutinized the impacts of having no insulation, a single-layer insulation, and Multilayer Insulation (MLI) techniques on thermal protection from environmental heat loads at the cryostat’s cold wall boundary, with a particular emphasis on the effectiveness of a single-layer insulation strategy against radiative heat load, a key precursor to MLI technology. The effectiveness of single-layer insulation was quantitatively analyzed for reducing heat load in large-scale rare event searches, using GERDA as an illustrative example and focusing on an optimized configuration. Performance metrics include ambient temperature, cryogenic liquid, emissivity, and the placement of insulation for optimal efficiency. The incorporation of a single intermediate layer positioned near the cold wall boundary results in a significant heat load reduction of 57% for the GERDA geometry compared to a scenario without such a layer. A feasible decrease in emissivity from the customary O(0.01) for insulation materials down to O(0.001–0.0001) could bring about substantial reductions in heat load, potentially by factors spanning approximately 8 to 90. In the scenario involving liquid helium (4.15 K), for example, as the ambient temperature surrounding the cryogen is lowered to (200, 150, 100, 50) K from room temperature, the heat load diminishes by 80%, 94%, 98.8%, and 99.9%, respectively. Moreover, optimally positioning single intermediate layer, crafted from ultra-radiopure material, as close as achievable to the cold wall boundary with minimal emissivity can yield a substantial reduction in heat load, estimated ∼(40–60)%, thereby diminishing the evaporation rate of the cryogenic liquid.

Effects of pulsed magnetic field intensity on the freezing rate and heat loads reduction of harvested mango and tomato

PurposeFresh fruits and vegetables (FV) are crucial global food resources, but the presence of heat loads during harvest adversely impacts their shelf life. While freezing technology provides an effective means of removing heat loads, it is an energy-intensive process and may consequently prove too costly for practical business viability. The growing interest in utilizing magnetic field (MF) technology during the freezing of fresh FV enhances the freezing rate and rapidly removes the heat loads of products.Design/methodology/approachIn the present study, pulsed magnetic field (PMF) pretreatment employing specific field strengths (9 T, 14 T and 20 T) was examined as a preliminary step before freezing mango and tomato and compared to the conventional freezing method (untreated) at − 18 °C.FindingsPMF pretreatment prior to freezing demonstrated a noteworthy enhancement in freezing rate by around 10 and 12% when compared with the conventional (untreated) freezing, which exhibited freezing rates of −0.08 °C/min and −1.10 °C/min for mango and tomato, respectively. The PMF pretreatment (at 20 T) provided a higher freezing rate (at p = 0.05) than the conventional freezing method reduced heat loads amounting to 1.1 × 107 J/kg oC and 2.9 × 106 J/kg oC, significantly (at p = 0.05) from mango and tomato, respectively. These reductions in heat loads were approximately more than 5% of the calculated heat loads removed during conventional freezing.Research limitations/implicationsMango and tomato samples were only tested; the results may lack generalizability. Therefore, researchers are encouraged to test for other products for further studies.Practical implicationsThe paper includes implications for the development of a rapid freezing technique, the development of “pulsed magnetic field” and for eliminating the problem associated with conventional (slow) freezing.Originality/valueThe study holds significance for the production of postharvest freezing technology, providing insightful information on the PMF-assisted freezing of cellular foods.

Numerical modeling of biophilic design incorporating large-scale waterfall into a public building: Combined simulation of heat, air, and water transfer

Biophilic design, which integrates nature into built environments, fosters beneficial human–nature interactions. It has gained traction as a promising solution to achieve a better trade-off between sustainability and occupants' well-being. However, despite its potential, quantitative assessment of biophilic design, particularly water elements, remains limited. This study addresses this gap using a two-step approach that quantifies the effects of biophilic water design on indoor hygrothermal conditions. We first developed a numerical model that couples building energy simulations with computational fluid dynamics to accurately predict the heat, air, and water transfer phenomena caused by waterfalls and ponds, and a novel mathematical model that precisely calculates water evaporation using water potential as the driving force of moisture transfer. Then, using this proposed method, we performed a numerical analysis of an actual public building as the reference space. This analysis quantitatively evaluated the effects of water elements on a hygrothermal environment and their impact on energy conservation. A series of comparisons and discussions based on the simulation results demonstrated the model's capability to accurately simulate the hygrothermal environment influenced by waterfalls and ponds. Moreover, the study confirmed and quantified the effects of waterfalls, specifically its significant evaporative cooling effect during summer, humidifying effect in winter, and heat load reduction benefits. These findings enrich our understanding of the impacts of biophilic water design on indoor environments and energy conservation, thereby contributing to the optimization of biophilic design practices.

Micropeltation in Myrtaceae: a neglected subject

The majority of taxa with peltate leaves are perennial herbs native to swampy or aquatic habitats or to mesic shaded understorey habitats. These large peltate leaves are formed by a meristematic bridge at the lamina–petiole junction. However, there are also several strong-light exposed, small-leaved, xero- and scleromorphic Myrtaceae with leaf peltation which is formed without a meristem fusion/bridge. Here, abaxial laminar tissue at the insertion point of the petiole forms a basal extension, so that a weak peltation occurs. This shifts the petiole onto the adaxial laminar surface. The formation of micropeltation in Myrtaceae leads to erect leaves that are strongly appressed to the shoot axis and the entire foliate, vertical shoots appear as “green columns”, a result that is also the case in taxa with reflexed minute leaves. It seems that micropeltation achieves the same goal as leaf reflexion in small-leaved taxa—reduction of heat-load and transpiration during the hottest phases of the day by a lower light interception at midday compared to the morning and evening. Thus, physiologically micropeltation and reflexion of minute leaves seem to be the result of convergent evolution.

A study on the enhancement of energy efficiency and indoor environment through the integration of solar photovoltaic modules in daylighting louver systems

The global energy demand is predicted to increase significantly, with a strong link between energy consumption and CO2 emissions. Lighting energy accounts for a substantial proportion of total energy consumption in buildings, with the potential to be reduced using daylighting louvers. Despite some drawbacks, integrating solar photovoltaic modules with louvers could enhance energy efficiency while addressing the increasing demand for renewable energy systems in new buildings. Therefore, this study explores the potential benefits of integrating solar photovoltaic (PV) modules into a daylighting louver system to simultaneously reduce lighting, cooling, and heating loads and generate solar power. The performance of the proposed louver system was experimentally compared to a conventional building-integrated photovoltaic (BIPV) system installed on a window. The daylighting louver system demonstrated significant improvements in indoor illumination and occupants’ experience compared to the BIPV system. Furthermore, the indoor air temperature in the space with the louver system increased by about 5 degrees compared to the BIPV system, indicating its contribution to heating load reduction. The power generation performance of the louver system reached up to 65 % of the BIPV system, with a total cumulative electricity generation of 64 %. The results suggest that the daylighting louver system can be expanded to enhance its efficiency and address the increasing demand for renewable energy system installations in new buildings. Future studies should investigate the potential of 2-axis or 3-axis louvers to further improve the system’s efficiency.

143 Short- and long-term effects of heat stress in cow-calf pairs adapted to tropical and subtropical regions

Abstract Chronic exposure to high temperatures and humidity can limit beef cattle performance in tropical/subtropical environments, regardless of breed. Despite better heat adaptability compared with Bos taurus cattle, heat-stressed Bos indicus cattle also experience an increase in body temperature above the physiological limit. As body temperature increases, cascades of behavioral and physiological events are triggered to lessen heat load but often at the expense of productive outcomes. Contrary to other species and feedlot beef cattle, the effects of heat stress on physiology and performance of grazing cow-calf pairs have not been evaluated in detail, particularly for Bos indicus cattle. Preliminary data showed opposite outcomes to heat stress in Bos indicus vs. Bos taurus cattle, limiting the implications of the existing data generated from studies using beef and dairy Bos taurus cattle. This presentation will share some nutritional and management practices to mitigate heat stress in grazing beef cattle. Practices mentioned herein include altering the timing of body weight (BW) growth pattern (stair-step, SST) and immunomodulatory feed ingredient (IFI) supplementation for replacement beef heifers, and maternal access to shade to reduce heat load. For 100 d before the breeding season, Bos indicus-influenced beef heifers grazing warm-season grasses received a constant supplementation amount or SST strategy (50 d of low then 50 d of high supplementation), with or without IFI. Under severe heat stress conditions, IFI supplementation reduced heifer vaginal temperature but did not increase their growth and reproduction, whereas the SST strategy lowered internal body temperature, enhanced growth performance and pregnancy success compared with a conventional constant supplementation practice. Our group is also focused on the critical need to determine the specific effects of heat stress mitigation during pre- and postnatal phases on physiology and performance of Bos indicus-influenced cow-calf pairs. Study 1 evaluated the impacts of maternal access to artificial shade from 83 d prepartum until 50 d postpartum on body thermoregulation, performance, and physiology of beef heifers and their first offspring. Removing maternal access to shade led to greater maternal respiration rate, vaginal and body surface temperatures and reduced maternal body condition score and calf BW at birth. Nonetheless, offspring born from cows with no access to shade were remarkably heavier during a 60-d post-weaning period and had decreased plasma indicators of inflammation and positive effects to humoral immune response. Study 2 is a multi-year, USDA/NIFA-funded study designed to capitalize on the ability of cattle to reprogram physiological/immunological systems following exposure to stress during gestation. Study 2 combined gestational and postnatal heat abatement to enhance the overall growth/immune/reproductive performance of grazing Bos indicus-influenced cow-calf pairs. Partial data on long-term growth and reproductive performance, physiology, metabolome, and microbiome of both cows and their female offspring will be shared in this presentation.

Pulse power supply for plasma aerodynamic actuators

The reduction of local heat load on the structural elements of aircraft or spacecraft vehicles due to the shock wave/boundary layer interaction can be successfully controlled in the future using a system of plasma actuators. The efficiency of plasma aerodynamic actuators operation is directly related to a power source. It determines a covered plasma area, an air flow speed and a thrust the actuator creates. The paper deals with the operation of a high-voltage source of sawtooth pulses with high efficiency for controlling plasma actuators. The pulse power source can be easily scaled for different nonlinear capacitive loads.

Overview of Large Helical Device experiments of basic plasma physics for solving crucial issues in reaching burning plasma conditions

Abstract Recently, experiments on basic plasma physics issues for solving future problems in fusion energy have been performed on a Large Helical Device. There are several problems to be solved in future devices for fusion energy. Emerging issues in burning plasma are: alpha-channeling (ion heating by alpha particles), turbulence and transport in electron dominant heating helium ash exhaust, reduction of the divertor heat load. To solve these problems, understanding the basic plasma physics of (1) wave–particle interaction through (inverse) Landau damping, (2) characteristics of electron-scale (high-k) turbulence, (3) ion mixing and the isotope effect, and (4) turbulence spreading and detachment, is necessary. This overview discusses the experimental studies on these issues and turbulent transport in multi-ion plasma and other issues in the appendix.

Multi-objective optimization design of aerothermal performance for turbine blade squealer tip with inclined suction-side rim

To optimize the inclined rim design, multi-objective optimization was numerically conducted on the suction-side rim of the squealer tip in the GE-E3 rotor blade. The RANS equations, incorporating with the standard k-ω model, were numerically solved. Through the implementation of a Kriging surrogate model coupled with the NSGA-II evolutionary optimization technique, six geometric parameters on the suction-side rim went through iterative optimization. This process yielded three optimized squealer tip geometries on the Pareto front: Structure 1 with minimum total pressure loss, Structure 2 with optimal comprehensive aerothermal performance, and Structure 3 with minimum tip heat load. Comparative analysis revealed that with the inner and external wall inclined toward the cavity and passage respectively, the optimization results in a 3 %–11 % reduction in tip heat load, accompanied by an 8.5 %–10.2 % reduction in aerodynamic loss, facilitated by an attenuated upper passage vortex (UPV) and strengthened tip leakage vortex (TLV). The critical inclined region of the external rim wall, spanning 7 %–80 %, influences the exit total pressure loss distribution. The inclined inner wall upstream of 50 % Cax obstructs coolant jets from exiting the cavity, reducing the heat load on the cavity bottom. However, the inclined external wall from 66 % to 90 % Cax amplifies the impingement of the scraping vortex (SV), increasing local heat transfer. The thermal behavior of Structure 1 is sensitive to changes in tip clearance, whereas Structure 2 and 3 show more robust advantages. As the clearance increased, the aerodynamic losses associated with the TLV rise for all three optimized tips, but losses from the UPV remain similar. This study provides a novel approach for designing efficient squealer tip geometries incorporating an inclined rim.

Energy management strategy for accurate thermal scheduling of the combined hydrogen, heating, and power system based on PV power supply

To solve the negative impact of renewable energy volatility on the power system, a combined hydrogen, heating and power system integrating alkaline water electrolysis, metal hydride hydrogen storage, and proton exchange membrane fuel cells (PEMFCs) is proposed. However, water electrolysis, hydrogen adsorption and PEMFC all generate heat, and how to use this heat is the key to improving the system efficiency. Therefore, four energy scheduling schemes are proposed in this study, aiming at making full use of waste heat to improve its energy utilization efficiency. The results show that the system heat is almost entirely utilized under the proposed four strategies. Meanwhile, the peak-valley strategy is more suitable for on-grid operation, and heat priority, peak clipping and load reduction strategy are more suitable for off-grid operation. Under the heat priority strategy, residual electricity and heat are the lowest. Under the peak clipping strategy, the current density of the PEMFC fluctuates the least and is maintained at 0.59 A cm−2 during the heat-led period. Under the load reduction strategy, during the heat-led period (5:00 p.m. ∼ 6:00 a.m.), the system electric power is lower than the power load for the shortest time, accounting for 23.93% of this operating duration.

INTEGRATION OF HYBRID ENERGY PLANT OPERATION

Integrated use means the use of several energy sources, all at the same time or in some combination. At the same time, it is possible to use exclusively renewable sources, which significantly limits user capabilities. More common and justified from many points of view is the use of both renewable and traditional sources, autonomous (universal boilers, diesel generators, gas turbine units, etc.) or centralized (power grid) sources. A correct assessment of such a combined energy system also requires taking into account the main component of the system - the consumer, that is, taking into account the features of the local network and nearby consumers, which will have a direct or tangible indirect effect on the operating mode of the complex of renewable sources. To ensure adequate power quality, energy storage systems can be used, and the need for them depends on the discreteness of energy flows and the requirements for power quality. In foreign terminology, combined systems are often called hybrid, reflecting the diversity of both energy sources and methods of combining them (sometimes this name extends to arbitrary complexes). However, the term “hybrid power supply” usually refers to a combination of installations using renewable and traditional energy sources. The article presents a new hybrid energy system that provides private households with electricity, hot water supply, heating and hot air in the required temperature range for comfortable living. Together with a wind power generator and an electric water heater, a heat pump, electricity and heat accumulators are used, which allows: - reducing the cost of thermal energy by reducing material consumption and equipment costs, saving organic fuel; produce electricity and send the excess to the state power grid; reduce heat load and environmental pollution. The automation system allows you to control the hybrid installation without human intervention all year round.

Ferromagnetic resonance measurement with frequency modulation down to 2 K.

Ferromagnetic resonance (FMR) spectroscopy is a powerful technique to study the precessional dynamics of magnetization in thin film heterostructures. It provides valuable information about the mechanisms of exchange bias, spin angular momentum transfer across interfaces, and excitation of magnons. A key desirable feature of FMR spectrometers is the capability to study magnetization dynamics over a wide phase space of temperature (T), frequency (f), and magnetic field (B). The design, fabrication, and testing of such a spectrometer, which uses frequency modulation techniques for improved detection of microwave absorption, reduces heat load in the cryostat and allows simultaneous measurements of inverse spin Hall effect (ISHE) induced dc voltages, is described in this paper. The apparatus is based on a 2-port transmitted microwave signal measurement using a grounded co-planar waveguide. The input radio frequency (RF) signal, frequency modulated at a tunable f-band, excites spin precession in the sample, and the attenuated RF signal is measured phase sensitively. The sample stage, inserted in the bore of a superconducting solenoid, allows magnetic field and temperature variability of 0 to ±5T and 2-310K, respectively. We demonstrate the working of this Cryo-FMR and ISHE spectrometer on thin films of Ni80Fe20 and Fe60Co20B20 over a wide T, B, and f phase space.

Thermal performance of a wooden pipe-embedded building envelope using a low-grade heat source in extreme cold climate conditions

A pipe-embedded wall can effectively reduce building energy consumption in winter. Most of the research on this concept to date has used traditional building materials such as concrete and brick. This paper reports on a wooden pipe-embedded wall allowing more flexible pipe locations, which can be used to reduce heat load in winter. An experimental assessment was developed to investigate the building assemblies thermal performance and the results were used to develop an understanding of its thermal energy saving potential, and as an input for the validation of a numerical model of same. A 3D computational fluid dynamics model of the pipe-embedded wall was developed and applied to assess the thermal performance of the wall under boundary conditions beyond the capabilities of the experimental assessment. Further, the influence of five parameters including the outdoor temperature and pipe positions were studied. A method was proposed for selecting the pipe layer's optimal location. The results show dual thermal impacts of the pipe layer: active heating and passive insulation. Using 8 °C water reduces internal surface heat transfer by 42.5 % under −20 °C outdoor temperature conditions. This is akin to an 18 °C outdoor temperature rise. Furthermore, another interesting result is that increasing the wall material thermal resistance can sometimes increase energy consumption. This study provides a reference for designing and optimizing net zero energy buildings in extreme cold climate conditions.

Four-dimensional conditional averaging tomography of rotating plasma ejection from cylindrical detached plasma

Detached plasma formation is a way to reduce the heat load on the wall in magnetic fusion devices. This study proposes a novel analysis technique consisting of the conditional averaging, sliding window, and tomography to reveal the spatiotemporal behavior of the rotating radial ejection event of detached plasma, which further contributes to local heat load reduction. The used equipment is a high-speed camera and an electrostatic probe located at the periphery of the linear plasma device NAGDIS-II. By applying this method, four-dimensional (4D) behavior of the emission structure along time (1D) and space perpendicular and parallel to the magnetic field (3D) was clarified; a rotating distorted structure appears as a precursor, which is then scraped and transported radially and axially. The proposed method is widely applicable to short-term rigid-body rotating structures, especially in linear plasmas.

Research on Relative Humidity and Energy Savings for Air-Conditioned Spaces without Humidity Control When Adopting Air-to-Air Total Heat Exchangers in Winter

In view of the problem that the exchange effectiveness is calculated according to a fixed value or only considering the influence of outdoor air parameters when analyzing the suitability of total heat recovery for plate heat recovery equipment in air-conditioned spaces without humidity control, the indoor humidity calculation model and moisture balance equation were established in this research to predict relative indoor humidity. Moreover, the relationship between total heat recovery, effective heat recovery, and the reduction in outdoor air heating load was analyzed using a psychrometric chart of the outdoor air treatment process. Referring to the standard for weather data of building energy efficiency in the Ningbo region, 6 typical days were taken as the calculation conditions. The moisture balance differential equation was solved using MATLAB software to obtain numerical solutions for the hourly indoor air humidity ratio, relative humidity, exchange effectiveness, and effective heat recovery when adopting an air-to-air total heat exchanger in an air-conditioned room of an office, classroom, or commercial building in the winter. The results indicate that, under the calculation conditions, the relative indoor humidity of commercial buildings is relatively high, making it unsuitable for a total heat exchanger. The relative humidity of indoor air in offices and classrooms can be maintained above 30%, and the total exchange effectiveness of a total heat exchanger is between 45% and 100%. The effective total heat recovery was calculated as sensible heat recovery under most calculation conditions.