Heating Ventilation Research Articles

Demand Response Potential of an Educational Building Heated by a Hybrid Ground Source Heat Pump System

Demand response (DR) enhances building energy flexibility, but its application in hybrid heating systems with dynamic pricings remains underexplored. This study applied DR via heating setpoint adjustments based on dynamic electricity and district heating (DH) prices to a building heated by a hybrid ground source heat pump (GSHP) system coupled to a DH network. A cost-effective control was implemented to optimize the usage of GSHP and DH with power limitations. Additionally, four DR control algorithms, including two single-price algorithms based on electricity and DH prices and two dual-price algorithms using minimum heating price and price signal summation methods, were tested for space heating under different marginal values. The impact of DR on ventilation heating was also evaluated. The results showed that applying the proposed DR algorithms to space heating improved electricity and DH flexibilities without compromising indoor comfort. A higher marginal value reduced the energy flexibility but increased cost savings. The dual price DR control algorithm using the price signal summation method achieved the highest cost savings. When combined with a cost-effective control strategy and power limitations, it reduced annual energy costs by up to 10.8%. However, applying the same DR to both space and ventilation heating reduced cost savings and significantly increased discomfort time.

CFD Simulation of Dynamic Temperature Variations Induced by Tunnel Ventilation in a Broiler House.

Maintaining the optimal microclimate in broiler houses is crucial for bird productivity, yet enabling efficient temperature control remains a significant challenge. This study developed and validated a computational fluid dynamics (CFD) model to predict temporal changes in indoor air temperature in response to variable ventilation operations in a commercial broiler house. The model accurately simulated air velocity and airflow distribution for different numbers of tunnel fans in operation, with air-velocity errors ranging from -0.22 to 0.32 m s-1. The predicted airflow rates through inlets and cooling pads showed good agreement with measured values with an accuracy of up to 108.1%. Additionally, the CFD model effectively predicted temperature dynamics, accounting for chicken heat production and ventilation effect. The model successfully predicted the longitudinal temperature gradients and their variations during ventilation cycles, validating its reliability through comparison with experimental data. This study also explored different variable inlet configurations to mitigate the temperature gradient. The variable inlet adjustment showed the potential to relieve the high temperatures but may reduce overall ventilation efficiency or intensify temperature gradients, which confirms the importance of optimising ventilation strategies. This CFD model provides a valuable tool for evaluating and improving ventilation systems and contributes to enhanced indoor microclimates and productivity in poultry houses.

Study on averaging method of event related potentials under noise

Open offices that make effective use of limited space and encourage dialogue, interaction, and collaboration among employees, are becoming an increasingly. However, productive work-related conversation might actually decrease the performance of other employees within earshot more so than other random, meaningless noises. The presence of noise during the performance of cognitive tasks involving such as memory, commonly causes a subjective experience of annoyance, which can lead to a decline in performance. This tendency is stronger in response to meaningful noise, such as music and conversation, than for meaningless noise, such as the sound of traffic, and heating ventilating and air-conditioning noise. It is well known that the Event-Related Potential (ERP) in the brain wave elicited by internal or external stimuli are related to the operation of selective attention. The present experiment was designed to determine the effects of the noise on ERPs in the auditory odd-ball paradigms. In order to examined differences in the ERP components due to the noise, performance of algorithm for estimating waveform of ERPs such as averaging method is evaluated.

Experience with the high mobility reception plate for source characterization according to EN 15657

EN 12354-5 describes methods for the prediction of noise from technical equipment based on the airborne sound radiation and the structure-borne sound excitation. This paper considers methods to characterize the source in terms of structure-borne-sound (sbs) emission. Laboratory methods for sbs source characterization are given in EN 15657. In current research and development projects at Rosenheim Technical University of Applied Sciences these methods are applied to fully characterize technical equipment such as heat pumps or ventilation systems. This includes the determination of the equivalent blocked force, the source single equivalent free velocity and the source single equivalent mobility. EN 15657 describes various methods to determine the required properties. Recent project experience showed that this is essentially necessary because the most suitable method has to be applied depending on the nature of the technical equipment. This paper presents experiences with indirect measurement methods on the high-mobility plate and the direct measurement method given in EN 15657.

Experimental and Simulation Study on Ventilation Heat and Humidity Damage in Deep Mining

Experimental and Simulation Study on Ventilation Heat and Humidity Damage in Deep Mining

Explore Wen Zhenheng's Painting and Calligraphy Protection Concept and Strategy in Zhangwu Zhi

Zhangwu Zhi, written by Wen Zhenheng in Ming Dynasty, is a monograph on the appreciation and protection of antiquities, which contains a wealth of ideas and strategies for the protection of calligraphy and painting. This paper aims to explore the concept and strategy of painting and calligraphy protection proposed by Wen Zhenheng in Zhangwu Zhi, and analyze its inspiration and reference to contemporary painting and calligraphy protection. Through the in-depth study of Zhangwu Zhi, this paper analyzes Wen Zhenheng's views and measures on the protection of calligraphy and painting, and discusses the storage environment, light regulation, air pollution control and pest control of calligraphy and painting collections. And put forward to establish a good storage environment, reasonable control of temperature and humidity, do a good job in the warehouse heat insulation, moisture-proof and ventilation management of calligraphy and painting protection strategies. These strategies had a profound impact on the preservation of calligraphy and painting at that time and later. Although Wen Zhenheng's ideas and strategies for the protection of calligraphy and painting still have certain limitations in the contemporary era, the protection measures and methods proposed by Wen Zhenheng still have inspiration and reference significance for the protection of contemporary calligraphy and painting. Through in-depth study and understanding of Wen Zhenheng's painting and calligraphy protection concept and strategy, we can better protect and manage the painting and calligraphy collection to ensure its safe inheritance and long-term preservation.

Progressive Dies for L-hanger Ducting (L-HD) Utilizing Low-Carbon Steel SPCC-SD Material: An Experimental and Numerical Analysis

Industrial developments, especially in the manufacturing and construction sectors, recognize L-hanger ducting as a critical component in HVAC (heating ventilation and air conditioning) ducting systems, which play a role in supporting and stabilizing air ducts. The L-Hanger ducting manufacturing process involves a series of stages, such as shearing, blanking, piercing, trimming, and bending processes. This research focuses on the design and simulation of dies and punches for piercing, blanking, and bending processes using 1.6 mm-thick SPCC-SD material. The aim of this research is to design and analyze progressive dies in order to increase the efficiency of the production process. A comprehensive calculation of the forces involved in the shearing, blanking, piercing, trimming, and bending processes is required in order to predict press machine tonnage requirements to support the production process. This research applies theoretical and numerical validation approaches. Theoretical analysis is used to calculate the overall forces, which are then compared with numerical results and verified through an experimental approach. By understanding and optimizing the design of progressive dies, it is hoped that we can increase the production efficiency of L-hanger Ducting and expand knowledge in the field of metal forming, contributing to the metal forming industry and supporting the development of science.

Determination of Turbulent Prandtl Number for Thermal Fluid Dynamics Simulation of HVAC Unit by Data Assimilation

Abstract Regarding high-precision temperature field prediction of a heating ventilation and air conditioning (HVAC) unit using thermal fluid dynamics simulation, the determination of the turbulent Prandtl number (Prt) was a key issue. In this study, we present an attempt to improve the accuracy of thermal fluid dynamics simulations in HVAC units by adjusting the Prt using data assimilation techniques. First, we simultaneously measured the velocity and temperature in the hot and cold air mixing zone of a simple HVAC model using particle image velocimetry and thermocouples. Second, we coupled data assimilation to the thermal fluid simulation model to determine the Prt in the mixing field. Finally, we proposed two functions of the Prt for high velocity and low velocity regions using multidimensional analysis. In the future, we believe that the Prt functions can be applied to thermal fluid simulations of actual HVAC unit to accurately predict performance without conducting prototype experiments, thereby contributing to reducing development cost and time of HVAC unit.

Modelling the maximum ceiling temperature with bifurcated plume in tunnel fires

Evaluation of the temperature profile induced by tunnel fire is of great significance for fire detection and structural damage assessment. In this work, a special plume model, namely, the “plume bifurcation” is introduced, and its impact on the temperature distribution is analysed theoretically. Full-scale tunnel fire experiments and numerical simulations are conducted to investigate the plume evolution under various heat release rates and ventilation conditions. Results show that the plume will sperate into two sub-streams under strong ventilation condition, resulting in the multi-dimensional plume movement pattern when rising. The sub-plume impingement point location, quantified by the longitudinal vertical deflection angle θv and horizontal bifurcation angle θh, is correlated with the fire heat release rate and ventilation condition. The plume bifurcation angle is 0 when the dimensionless ventilation velocity V′≤0.33, marking a single-stream plume; and rapidly increase and then slowly decrease with V′ when V′>0.33, representing the sudden occurrence and decay trend of plume bifurcation with the ventilation velocity. Finally, a novel bifurcated plume-based model to estimate the maximum ceiling temperature is proposed. This study reveals the role of multi-dimensional smoke movement in reshaping the temperature field, providing new perspectives for a deeper understanding of the smoke transport behaviour in longitudinally ventilated tunnel fires.

Investigating Factors Impacting Power Generation Efficiency in Photovoltaic Double-Skin Facade Curtain Walls

Photovoltaic double-skin glass is a low-carbon energy-saving curtain wall system that uses ventilation heat exchange and airflow regulation to reduce heat gain and generate a portion of electricity. By developing a theoretical model of the ventilated photovoltaic curtain wall system and conducting numerical simulations, this study analyzes the variation patterns of the power generation efficiency of photovoltaic glass for different inclination angles, seasons, thermal ventilation spacing, and glass transmittance in the photovoltaic double-skin curtain wall system. The results indicate a positive correlation between the surface temperature of photovoltaic glass and both ground temperature and solar radiation intensity. Additionally, photovoltaic power generation efficiency is generally higher in spring and autumn than in summer and winter, with enhanced power generation performance observed. At an inclination angle of 40°, photovoltaic panels receive optimal solar radiation and, consequently, produce the maximum electricity. Furthermore, as the ventilation spacing increases, the efficiency of power generation initially rises, reaching a peak at approximately 0.4 m, where it is 0.4% greater than at a spacing of 0.012 m. For a photovoltaic glass transmittance of 40%, the highest photovoltaic power generation efficiency is 63%, while the average efficiency is 35.3%. This has significant implications for the application and promotion of photovoltaic double-skin glass curtain walls.

Dynamic energy optimization strategy to provide appropriate thermal comfort and fresh air under occupants’ different activity types

An effective strategy for optimizing indoor air distribution in stratum ventilation heating systems under different types of human activity has been proposed, in order to provide appropriate thermal comfort while exploiting the potential for energy savings. The stratum ventilation was optimized using strategy 1 (the optimization strategy of three ventilation performance indicators based on VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR)), the strategy 2 (the optimization strategy with constraint based on VIKOR) and the strategy 3 (the optimization strategy aimed at energy conservation), respectively. These strategies provide optimal indoor air distribution within a stratum ventilation system that is influenced by various factors (i.e. supply air temperature, supply air vane angle, supply air velocity, metabolic rate, clothing insulation and outdoor air temperature). Firstly, the parameters of the stratum ventilation system are obtained using Computational Fluid Dynamics (CFD) software. In addition, using the simulation results as input variables, predictive models of ventilation performance (i.e., PMV, local mean air age (LMAA) and energy consumption) was developed using Artificial Neural Network (ANN). Finally, by optimizing the proposed ANN based strategy 1, strategy 2 and strategy 3, the ventilation performance is output. The proposed strategy 1 provides a comfortable indoor environment and saves energy, and compared to the strategy 1, the strategy 3 saves more energy while ensuring that thermal comfort meets the requirements. In addition, considering the optimization of clothing insulation while providing appropriate thermal comfort also indirectly saves energy. Moreover, these strategies also work well as the outdoor air temperature changes.

Advancing building energy efficiency: A deep learning approach to early-stage prediction of residential electric consumption

Enhancing building energy efficiency underscores the critical need for innovative predictive models to mitigate environmental issues from high energy consumption, especially in residential areas with air-conditioning and heating ventilation systems. This study introduces the use of Long Short-Term Memory (LSTM) networks for early prediction of residential electric consumption, representing a significant innovation in the field. Unlike traditional Deep Neural Network (DNN) and Artificial Neural Network (ANN) models, Long Short-Term Memory networks efficiently process time-series data, predicting future energy usage with unmatched accuracy. The Long Short-Term Memory model exhibited superior training efficiency, requiring only 2.69 s for over 500 test cases, outperforming Deep Neural Network and Artificial Neural Network models, which took 5.26 and 3.88 s, respectively. Its predictive accuracy, evidenced by an R-squared value of 0.97, surpasses the 0.95 and 0.92 of Deep Neural Network and Artificial Neural Network models, respectively. This breakthrough enables accurate predictions of annual energy usage before construction starts and aids in identifying energy efficiency improvements early in the design process. Applying Long Short-Term Memory networks in this context marks a substantial advancement in predictive modeling for building energy consumption, equipping architects and engineers with a vital tool for designing energy-efficient buildings from the beginning. The innovation and quantitatively proven effectiveness of the Long Short-Term Memory model highlight its potential to revolutionize early-stage building design strategies, filling a crucial gap in the existing literature.

Effects of longitudinal ventilation and GHEs on geothermal energy extraction and HRC in high geothermal tunnels

With the excavation of deep tunnels, the problem of high geothermal heat is becoming more and more prominent. However, high geothermal heat can be utilized as a renewable energy source. In order to effectively reduce thermal damage and utilize geothermal energy, it is necessary to study the effects of longitudinal ventilation and ground heat exchanges (GHEs) on the heat-regulating circle of the surrounding rock. In this study, an experimental platform was designed and constructed in a laboratory to test different geothermal heat exchanger flow rates and ventilation air velocities and to monitor the heat extraction from the geothermal heat exchanger, the ventilation heat extraction, and the temperature field of the surrounding rock. The experimental results show that when the temperature field tends to be stabilized, the flow rate and ventilation velocity of the GHEs are closely related to the temperature distribution of the surrounding rock. The initial heat storage and heat replenishment capacity of the enclosing rock have a great influence on the heat extraction efficiency. Ventilation has a great influence on the heat extraction efficiency of GHEs, and the optimal wind speed range is 1.5∼2 m/s considering the cooling and heat extraction efficiency. When the wind speed is less than 1.5 m/s, the heat extraction efficiency of GHEs can be improved, and the total heat transfer can be increased. When the wind speed is greater than 1.5 m/s, the situation is reversed. The thermal entropy theory for circular tunnels is not fully applicable to arched tunnels containing GHEs.

Self-powered electrochromic smart window helps net-zero energy buildings

Net-zero energy buildings are becoming an important energy-saving and low-carbon technology for global environmental protection and resource conservation. As the least energy-efficient building components, windows have promoted the development of electrochemically light/thermal management, where smart windows without external electrical supplies are highly desired for net-zero energy buildings. Here, we develop a self-powered electrochromic smart window system to regulate solar radiation transmittance, constructed by a triboelectric nanogenerator (TENG) and a high-performance electrochromic device. The visible–near-infrared (VIS-NIR) dual-band electrochromic device is well-designed based on an eco-friendly low-energy demand phenothiazine redox ionic liquid, demonstrating a fast switching response of ﹤1.9 s, a large transmittance modulation of >51.8 %, and outstanding electrochemical durability (5.5 % attenuation after 4000 cycles). Upon continuous pressing/releasing motions, the integrated TENG-powered electrochromic smart window (TECSW) displays a prompt light/thermal management behavior with desirable privacy preservation performance (transmittance modulation of 51 % in the visible region) and excellent thermal management property (12.3 °C reducti°n). The whole-building energy simulations show that TECSW can save 347.79 MJ/m2yr (amounting to 96.60 kWh/m2yr) of operational Heating Ventilation Air Conditioning (HVAC) warming/cooling energy consumption among 34 cities in China, accounting for 17.25 % of the total energy consumption. This research provides new insight into designing green and energy-efficient smart windows for net-zero energy buildings.

When thermochromic material meets shape memory alloy: A new smart window integrating thermal storage, temperature regulation, and ventilation

Traditional windows have poor thermal insulation performance, resulting in significant indoor heat loss in winter and outdoor heat entry in summer. Thermochromic smart windows can effectively block solar radiant heat by automatically adjusting light transmittance, thereby reducing air conditioning loads and leading to significant energy savings. In this study, the poly N-isopropyl acrylamide (PNIPAm)-based thermochromic hydrogel, modified MXene nanoparticles, and NiTi shape memory alloy (SMA) are integrated to endow the smart window with heat storage, temperature control, and ventilation. The smart window achieves 88.6% visible light transmission and 70% solar modulation. The inclusion of MXene nanoparticles further enhances photothermal response efficiency, while the ventilation system ensures efficient and fresh indoor air circulation. Compared to the common glass, the smart window reduces the indoor temperature by 8 °C, demonstrating its excellent temperature regulation ability. Simulation results indicate that in Shanghai, Cairo, Singapore, and Kuwait, the employment of thermochromic smart windows can reduce heating, ventilation, and air conditioning energy consumption (HVAC) by 32.6%, 49.9%, 42.7%, and 34.1%, respectively. This versatile thermochromic smart window is expected to significantly improve building efficiency and occupant comfort, offering a sustainable solution for future building designs.

Application of energy combined thermal comfort in intelligent building management in complex environments

The efficient operation of heating ventilation and air conditioning systems relies on advanced control strategies. However, current control methods are often limited by issues such as uncertain system parameter information and spatial coupling constraints related to the supply rate of the air supply fan. To this end, an energy joint thermal comfort management method for complex environments in multiple regions is proposed. The long-term total cost minimization of the system is established, and then the Lyapunov optimization technology is used to design the distributed control algorithm. Simulation validation shows that the proposed method reduces the energy cost by an average of 11.24% compared to other methods with a thermal discomfort cost coefficient of 0. The average temperature deviation in the area is improved by 0.15 °C and 0.68 °C, respectively. The method saves more than 10% of the total energy cost under different thermal perturbations with an average total temperature deviation of 0.04 °C. The results indicate that the proposed energy joint thermal comfort management method can flexibly balance energy costs and user thermal comfort without knowing any prior information of system parameters, which can also greatly protect user privacy information. This method has application value in the control of heating ventilation and air conditioning systems in complex environments such as commercial buildings.

Integrating Building Management Systems in High-Rise Structures using Building Information Modeling

Rapid industrialization and population growth in urban areas has resulted in scarce land resources thus changing builtform tremendously. Complex construction such as high-rise structures are becoming an essential requirement in urbanareas. Efficient Building Management System (BMS) such as fire safety, heating ventilation and air-conditioning,security, and surveillance along with the operation and maintenance is crucial for high-rise construction projects. Theconstruction industry is one of the most labor-intensive industries in the world with a human centric managementapproach. With the advent of computer technologies, planning and management of building systems in a constructionproject have become easier. The concept of Building Information Modeling (BIM) to manage building managementsystems in construction projects is gaining popularity. In this study, an integrated framework is proposed that includesnumerous aspects of building management systems in high-rise structures with a dynamic BIM model. This proposedframework was explored with a case illustration of a multi-story building. Preliminary results of the model arepresented herewith.

The Advection Boundary Law in absence of mean flow: Passivity, nonreciprocity and enhanced noise transmission attenuation

Sound attenuation along a waveguide is intensively studied for applications ranging from heating and air-conditioning ventilation systems, to aircraft turbofan engines. In particular, the new generation of Ultra-High-By-Pass-Ratio turbofan requires higher attenuation at low frequencies, in less space for liner treatment. This demands to go beyond the classical acoustic liner concepts and overcome their limitations. In this paper, we discuss an unconventional boundary operator, called Advection Boundary Law, which can be artificially synthesized by electroactive means, such as Electroacoustic Resonators. This boundary condition entails nonreciprocal propagation, meanwhile enhancing noise transmission attenuation with respect to purely locally-reacting boundaries, along one sense of propagation. Because of its artificial nature though, its acoustical passivity limits are yet to be defined. A thorough numerical study is provided to assess the performances of the Advection Boundary Law, in absence of mean flow. An experimental test-bench validates the numerical outcomes in terms of passivity limits, non-reciprocal propagation and enhanced isolation with respect to local impedance operators. Guidelines are outlined to properly implement the Advection Boundary Law for optimal noise transmission attenuation. Moreover, the tools and criteria provided here can also be employed for the design and characterization of other innovative liners.

Research on working characteristics of composite two-stage ventilation heat recovery system with heat pipe and heat pump

In this paper, a composite two-stage ventilation heat recovery system with heat pipe and heat pump is proposed, heat pipe is used to recover the exhaust air energy to improve the operating performance of the system under all operating conditions. The split heat pipe heat exchanger is designed and manufactured, the working characteristics and performance of the composite heat recovery system under different working conditions are tested, and it is compared with the parallel-loop heat pump ventilation heat recovery system also. The results show that the optimal working fluid charge rate of the split heat pipe used in the composite system is 50 %–60 %, the temperature efficiency of the composite system in winter is higher than 64.31 %, the heating COP is up to 7.17, and the total heating capacity is 5.09 kW. Temperature efficiency and heating capacity of the system are 4.01 %–66.6 % and 7.68 %–67.19 % higher than that of the double loop heat pump heat recovery system, respectively.

Energy geo-structures: A review of their integration with other sources and its limitations

Ground Source Heat Pumps, in the framework of Shallow Geothermal Energy Systems, outperform conventional Heating Ventilation and Air Conditioning systems, even the high efficiency Air Source Heat Pumps. At the same time, though, they require considerably higher installation costs. The utilization of dwellings' foundations as ground heat exchanger components has recently demonstrated the potential to generate significant cost reductions primarily attributed to the reduction in expenses associated with drilling and backfill material (grout). These elements are referred to in the literature as Thermo-Active Structures or Energy Geo-structures (EGs). The current study employs a ‘mixed studies’ review (i.e., literature review, critical review and state-of-the-art review) methodology to comprehensively examine and assess the compatibility and integration of different renewable energy sources and environmentally friendly technologies with foundation elements deployed as EGs. These mainly include heat pumps, district heating and cooling networks, solar-thermal systems, waste heat, biomass and other types such as urban structures. Emphasis has been given on the advancement on this area, with the current study identifying and addressing two primary categories. The first category involves the integration of EG elements with sources that are able to supply green electricity, referring to renewable energy electricity obtained from on-grid or off-grid integration. The second category, involves a direct or indirect integration with sources that provide heat, or vice versa. The technical and non-technical barriers of such integrations have been discussed in detail, with the technical challenges generally involving engineering design, and system optimization, whereas non-technical challenges encompassing the economic, social, and policy domains.