bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-/Four-Dimensional Ultrasound Technology in Speech Research
Authors: Lulich Steven M. , Pearson William G.
Published: August 2019

Purpose

Speech production is a complex 3-dimensional (3D) process, and yet most of what is known about it is derived from 2D midsagittal data. The relatively recent development of safe 3D imaging technologies (including magnetic resonance imaging and ultrasound) provide new opportunities to revisit and reformulate what is already known and to push the boundaries of current knowledge still further. A particularly useful imaging modality for this purpose is 3D/4D ultrasound, which until very recently was not well suited for studies in speech research. This technical report presents an overview of what 3D/4D ultrasound can contribute to speech research, with a focus on 2 demonstrations.

Conclusion

The 1st demonstration illustrates how 3D/4D ultrasound makes it possible to image certain vocal tract anatomical structures and planes that conventional 2D ultrasound is not capable of imaging. The 2nd demonstration illustrates how 3D/4D ultrasound can be combined with static 3D magnetic resonance imaging to provide new insight into the temporal pervasiveness and spatial extensiveness of lateral contact between the tongue and palate–teeth during speech production.
Breaking cosmic degeneracies: Disentangling neutrinos and modified gravity with kinematic information
Authors: Hagstotz Steffen , Gronke Max , Mota David F. , Baldi Marco
Published: August 2019

Searches for modified gravity in the large-scale structure try to detect the enhanced amplitude of density fluctuations caused by the fifth force present in many of these theories. Neutrinos, on the other hand, suppress structure growth below their free-streaming length. Both effects take place on comparable scales, and uncertainty in the neutrino mass leads to a degeneracy with modified gravity parameters for probes that are measuring the amplitude of the matter power spectrum. We explore the possibility to break the degeneracy between modified gravity and neutrino effects in the growth of structures by considering kinematic information related to either the growth rate on large scales or the virial velocities inside of collapsed structures. In order to study the degeneracy up to fully non-linear scales, we employ a suite of N-body simulations including bothf(R) modified gravity and massive neutrinos. Our results indicate that velocity information provides an excellent tool to distinguish massive neutrinos from modified gravity. Models with different values of neutrino masses and modified gravity parameters possessing a comparable matter power spectrum at a given time have different growth rates. This leaves imprints in the velocity divergence, which is therefore better suited than the amplitude of density fluctuations to tell the models apart. In such models with a power spectrum comparable to ΛCDM today, the growth rate is strictly enhanced. We also find the velocity dispersion of virialised clusters to be well suited to constrain deviations from general relativity without being affected by the uncertainty in the sum of neutrino masses.
Tidal response of rocky and ice-rich exoplanets
Authors: Tobie G. , Grasset O. , Dumoulin C. , Mocquet A.
Published: August 2019

The amount of detected planets with sizes comparable to that of the Earth is increasing drastically. Most of the Earth-size planet candidates orbit at close distances from their central star, and therefore are subjected to large tidal forces. Accurate determination of the tidal parameters of exoplanets taking into account their interior structure and rheology is essential to better constrain their rotational and orbital history, and hence their impact on climate stability and planetary habitability. In the present study, we compute the tidal response of rocky and ice-rich solid exoplanets for masses ranging between 0.1 and 10 Earth masses using a multilayer approach and an Andrade rheology. We show that the amplitude of tidal response, characterized by the gravitational Love number,k2, is mostly controlled by self-gravitation and increases as a function of planet mass. For rocky planets,k2depends mostly on the relative size of the iron core, and hence on the bulk iron fraction. For ice-rich planets, the presence of outer ice layers reduces the amplitude of tidal response compared to ice-free rocky planets of similar masses. For both types of planet (rocky and ice-rich), we propose relatively simple scaling laws to predict the potential Love number value as a function of radius, planet mass and composition. For the dissipation rate, characterized by theQ−1factor, we did not find any direct control by the planet mass. The dissipation rate is mostly sensitive to the forcing frequency and to the internal viscosity, which depends on the thermal evolution of the planet, which is in turn controlled by the planet mass and composition. The methodology described in the present study can be applied to any kind of solid planet and can be easily implemented into any thermal and orbital evolution code.
Broadband spectroscopy of astrophysical ice analogues
Authors: Giuliano B. M. , Gavdush A. A. , Müller B. , Zaytsev K. I. , Grassi T. , Ivlev A. V. , Palumbo M. E. , Baratta G. A. , Scirè C. , Komandin G. A. , Yurchenko S. O. , Caselli P.
Published: August 2019

Context.Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region.

Aims.Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range.

Methods.We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data.

Results.The complex refractive index in the wavelength range 1 mm–150μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature.

Conclusions.The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.
MUSE library of stellar spectra
Authors: Ivanov Valentin D. , Coccato Lodovico , Neeser Mark J. , Selman Fernando , Pizzella Alessandro , Dalla Bontà Elena , Corsini Enrico M. , Morelli Lorenzo
Published: August 2019

Context. Empirical stellar spectral libraries have applications in both extragalactic and stellar studies, and they confer an advantage over theoretical libraries because they naturally include all relevant chemical species and physical processes. In recent years we have seen a stream of new sets of high-quality spectra, but increasing the spectral resolution and widening the wavelength coverage means resorting to multi-order echelle spectrographs. Assembling the spectra from many pieces results in lower fidelity of their shapes.

Aims. We aim to offer the community a library of high-signal-to-noise spectra with reliable continuum shapes. Furthermore, the use of an integral field unit (IFU) alleviates the issue of slit losses.

Methods. Our library was built with the MUSE (Multi-Unit Spectroscopic Explorer) IFU instrument. We obtained spectra over nearly the entire visual band (λ ∼ 4800–9300 Å).

Results. We assembled a library of 35 high-quality MUSE spectra for a subset of the stars from the X-shooter Spectral Library. We verified the continuum shape of these spectra with synthetic broadband colors derived from the spectra. We also report some spectral indices from the Lick system, derived from the new observations.

Conclusions. We offer a high-fidelity set of stellar spectra covering the Hertzsprung-Russell diagram. These can be used for both extragalactic and stellar studies and demonstrate that the IFUs are excellent tools for building reliable spectral libraries.
Effects of the room temperature sensor position and radiator sizing on indoor thermal comfort and energy performances
Authors: Campana Jean Pierre , Schuss Matthias , Mahdavi Ardeshir , Morini Gian Luca
Published: August 2019

In this paper, a simplified zonal model for the evaluation of the spatial distribution of the air temperature in a thermal zone is presented. This model, in which the air flow is caused only by buoyancy forces, is implemented in ALMABuild. The model is used for the analysis of the effect of the temperature sensor positioning on the control system behaviour and on the indoor comfort conditions. This analysis is performed considering a multi-zone building composed by three offices, focusing the evaluation to the central one. The office is heated by means of a radiator in which the hot water flow rate is varied by a valve controlled via a room temperature sensor. By means of numerical simulations, indoor comfort conditions, energy consumptions and control system response are evaluated for three different sensor positions (far from the radiator, in the middle of the office, close to the radiator), two radiator sizes (one obtained by imposing a high supply water temperature, 80 °C, the other a low supply temperature, 60 °C) and two control strategies (weather compensation and fast restart). The results presented in this study and demonstrate how complete dynamic energy simulation tools can provide to the designer important information, like the room temperature sensor position that should be close to the emitter and far from cold external walls, for the optimal design of HVAC systems.
A Novel Spherical Packed Bed Application on Decentralized Heat Recovery Ventilation Units
Authors: GENC Alper Mete , KARADENIZ Ziya Haktan , EKREN Orhan , TOKSOY Macit
Published: August 2019

Decentralized heat recovery ventilation (HRV) systems are assumed as simple solutions to obtain a healthy and comfortable indoor environment. A wall or window mounted compact version of decentralized HRV systems (mono unit) are used for small scale, mostly residential applications. A fan and a heat exchanger are the critical components of this compact system. The flow capacity of these units are down to 10 m3/h, where efficiencies over 90% are commonly declared by the manufacturers. On the other hand, spherical packed beds (SPD) are widely used in the heat transfer applications such as; chemical reactors, grain driers, nuclear reactors, thermal storage in buildings and in solar thermal power plants, due to operational convenience. These systems are operated under steady flow conditions, unlike decentralized HRV systems which are designed for cyclic operation. In this study, heat recovery performance of a spherical packed bed heat exchanger for a decentralized HRV system is investigated. A one dimensional mathematical model for a SPD is obtained and an in-house computer code is developed to solve the transient heat transfer inside the packed bed under cyclic operation conditions. Well known convenient correlations were used for pressure drop calculations. A number of bed and sphere diameters were studied in a wide range. Various flow time and number of cycles were studied for the hot and cold flow to understand the SPD performance for HRV applications. This novel application also has the potential for regenerative heat recovery systems.
Performance investigation of indoor thermal environment and air handling unit in a hub airport terminal
Authors: Lin Lin , Li Lingshan , Liu Xiaochen , Zhang Tao , Liu Xiaohua , Wei Qingpeng , Gao Xiaohui , Wang Tao , Tu SiDong , Zhu SiPing , Zou WenBo , Qu Hong
Published: August 2019

Airport terminal is a typical large space building with large high interspaces and multitudinous functional zones. The task of heating, ventilation and air conditioning (HVAC) system is to ensure the thermal environment of these zones with different functions. A typical terminal in cold region of China is investigated in present paper, where indoor environment and performance of air conditioning system in summer are emphasized. The results indicate that the indoor temperature and humidity parameters at a height of 1.5 m in each zone of the terminal can be effectively controlled. The indoor temperature at a height of 1.5 varies in the range of 24~27°C, and the temperature difference is 0.5~4.9°C in the vertical direction. The temperature at the top of the terminal is greatly affected by the outdoor temperature where is higher and fluctuates obviously, while the temperature at the height of the occupant area is lower and more stable under the control of the air-conditioning system. The indoor carbon dioxide concentration is also at a reasonable level, all below 900 ppm, indicating that the equivalent outdoor air volume per capita is greater than 35 m3/h. Even in the case of high load caused by flight delays, the thermal environment in the terminal can be basically controlled at a comfortable level. As for the air handling unit, air handling process is tested to investigate the cooling capacity. The results show that the actual water supply of the AHU is relatively higher than the set value, but the air volume is almost equal to the set value which leads to an unsatisfactory energy efficiency. The tested energy efficiency ratio (EER) of AHU is only 5~7, almost approaching to that of the cooling plant. Reducing air flow rate could greatly improve the EER of the current air-conditioning system.
A PCM based cooling system for office buildings: a state of the art review
Authors: Paroutoglou Evdoxia , Afshari Alireza , Bergsøe Niels Chr. , Fojan Peter , Hultmark Göran
Published: August 2019

Cooling of air in buildings has a significant effect on thermal comfort and, consequently, productivity of office occupants. This study presents a state of the art review of energy efficient cooling systems that will provide occupants in buildings with satisfying thermal comfort. Using high-temperature cooling systems combined with renewable energy sources increases the energy efficiency in buildings. Latent heat thermal energy storage (LHTES) using Phase Change Materials (PCM) is a renewable energy source implemented in space cooling applications due to its high energy storage density. Since the share of commercial buildings in need of cooling is increasing, there is a need for developing new technical solutions in order to reduce the energy use without compromising thermal comfort. To this end, a proposed ventilation system, preliminarily analyzed in this paper, is expected to reduce further the energy use. The ventilation system is composed of an air handling unit, a 2-pipe active chilled beam system, and a cooling system including a LHTES using PCM. Few researchers have investigated chilled water air-conditioning systems that integrate a LHTES using PCM. In this review, function characteristics, possibilities and limitations of existing systems are discussed.
Performance Evaluation of An Innovative Column Attachment Ventilation
Authors: Yin Haiguo , Li Angui , Li Linna , Wu Rui
Published: August 2019

An innovative column attachment ventilation (CAV) was proposed for heating, ventilating and air-conditioning (HVAC) systems and its performance was evaluated through experimental investigation and numerical modeling. Airflow pattern, air temperature distribution, air diffusion performance index (ADPI), predicted mean vote (PMV), and draught rate (DR), were used as the performance indicators to investigate the air distribution performance. The ventilation effectiveness for heat removal in the CAV mode was compared with a conventional mixing ventilation (MV). The results showed that the discharged air from the linear slot diffuser can attach to the column and enter into the occupied zone creating air lake phenomenon. The airflow spread over the floor in a radial pattern behaved as a stratified air distribution like displacement ventilation (DV), providing good air quality and comfort level for occupants. Moreover, the heat removal effectiveness in the CAV was found to be higher than in the MV, i.e. 1.32 in the C-CAV and 1.29 in the S-CAV modes. The column attachment ventilation can achieve thermal comfort in the occupied zone without local discomfort caused by high vertical temperature difference and draught, and this ventilation strategy could be expected as a new and efficient air distribution pattern for different HVAC applications.
Influence of Ceiling Height on Airflow and Particle Distribution in an Operating Room
Authors: Agirman Aleyna , Cetin Yunus Emre , Avci Mete , Aydin Orhan
Published: August 2019

Bacteria-carrying particles released by surgical staff are the main factors leading to surgical site infections (SSI). Operating rooms must be designed to reduce risks of such infections. In this numerical study, the effect of different ceiling heights on particle dispersion and deposition are studied for an operating room with laminar airflow (LAF) system. Two different particle diameters (12 and 20 ìm) are tested under three different ceiling heights (2.43–2.8–3.0 m) at a constant air change rate (ACH=20). Numerical predictions are performed by using the commercial software ANSYS Fluent 16.0. The results reveal that decreasing of the ceiling height reduces the amount of particle deposited on the surgical table.
Analysis of Defogging Performance, Thermal Comfort, and Energy Saving for HVAC System Optimization in Passenger Vehicles
Authors: Ono Taro , Nagano Hideaki , Shiratori Suguru , Shimano Kenjiro , Kato Shinsuke
Published: August 2019

The heating, ventilation, and air-conditioning (HVAC) system in a vehicle is used for both defogging the windshield and ensuring the thermal comfort of passengers. A challenge is that energy savings in the HVAC system lead to decreased system performance. The three objective functions, i.e. defogging performance, thermal comfort, and energy savings, these must be considered in parallel to find the optimized control strategy. In the present study, a transient numerical simulation of the in-vehicle environment is performed and the dependency of performance on the air flow rate and supplied air temperature is analyzed. The criteria of defogging performance and thermal comfort are determined as the constrained conditions. The results show a trade-off relationship between the air flow rate and air temperature in defogging performance and thermal comfort; however, their sensitivities depend on the conditions and the time elapsed. As for transient defogging performance, the air flow rate has greater impact than airflow temperature. The air flow rate and the air temperature are comparable in their effects on equivalent temperature, which is employed as the index of the thermal environment. The blowing condition range that fulfills the criteria makes a transition to a low-energy condition with time elapsed. A control strategy for the air flow rate and temperature is derived considering the transient and steady-state conditions.
Can we meet the requirement for ultra-clean operation room (10CFU/m3) with dilution ventilation?
Authors: Pedersen Christoffer , Cao Guangyu , Drangsholt Finn , Stenstad Liv-Inger , Skogås Jan Gunnar
Published: August 2019

The objective of this study is to analyse what conditions may, and may not take place during surgery in a dilution ventilated operating room (OR), to fulfil an ultra-clean requirement (10 CFU/m3). To achieve the objective, literature review and a mock surgery with air sampling was performed. Colony forming unit (CFU) measurements were conducted to estimate the bacterial concentration in the air. During the mock surgery, the following conditions was present: a clean air suit, surgical gowns, double-tie-on masks and surgical hoods was used by all surgical members, except for the non-sterile members whom did not wear surgical gowns. 5 surgical members + 1 patient were present, 0 door openings occurred and a predefined movement and action plan set the activity level. The average CFU/m3 for the mock surgery was 15,4(SD:5,4). The CFU/m3 during a high activity period was about 21,5% higher than in low activity periods. With the conditions simulated in the mock surgery, and the clothing used, the OR were not able to fulfil the ultra-clean requirement. To reduce the CFU/m3 the activity level needs to be reduced. The literature shows that to meet the ultra-clean requirement all staff members should wear single-use clean air suits made of non-woven fabric, surgical masks, and a surgical hood. Traffic level needs to be minimized and a calm intraoperative behaviour needs to be maintained by the surgical staff. The amount of people present seems less important compared to the activity level taking place during surgery.
Investigation of indoor environment quality in the storage areas of NTNU Gunnerus Library
Authors: Svenneby H. M. , Cao G.
Published: August 2019

The NTNU Gunnerus Library is one of the most important cultural heritage libraries in the Nordic countries. The collections consist of a combination of materials with different levels of instabilities. In view of this fact, the target condition needs to be a compromise in order to maintain the required indoor environmental quality for the storage area. There are a number of consequences as a result of inadequate conditions of relative humidity, air temperature and air distribution. The main categories of degradation are biological, mechanical and chemical degradation. Literature states, that to minimize degradation of the cultural material stored at the library, it is important to maintain stable thermo-hygrometric values. The analysis of the measurements indicates a wide range of thermo-hygrometric values to which the storage area is exposed. Thus, the comfort zone, which is determined by the optimal condition including seasonal- and short-time fluctuation range, is often exceeded and the content of the storage is exposed to a substantial threat of damage.
Performance investigation of a novel hybrid deep-dehumidification process using liquid desiccant
Authors: Guan Bowen , Liu Jun , Liu Xiaohua , Zhang Tao , Chen Liangliang , Chen Xiaoyang
Published: August 2019

As one of the essential dehumidification ways, liquid desiccant air conditioning system has developed quickly in recent years, especially in the deep dehumidification field. A novel hybrid deep- dehumidification system using liquid desiccant driven by heat pump is proposed in this study to simplify the arrangement of air ducts and guarantee a competitive energy efficiency. In the proposed process, the regenerator, condensing dehumidifier and liquid dehumidifier are cascaded, and the process air flow through them sequentially. Heat pump cycle is utilized in the system, where the cooling capacity of evaporator is used to cool the liquid desiccant in dehumidifier, and the heating capacity of condenser is used for desiccant regeneration. The humidity ratio of the supplied air is as low as 2.6 g/kg. No extra regeneration air or corresponding air duct are needed in the proposed process, which obviously simplifies the layout of the system. Performance of the proposed system is then analysed by numerical results. It’s indicated 17.5~29.2% energy is saved compared with the conventional deep dehumidification process with two-stage heat pump, with the outlet humidity ratio of 2.6 g/kg.
Numerical models development for unidirectional air flow diffusers with lobed and circular orifices
Authors: Tacutu Laurentiu , Nastase Ilinca , Bode Florin , Croitoru Cristiana , Lungu Catalin
Published: August 2019

In order to achieve more realistic boundary conditions on the inlet of a ventilation system it is necessary to study the influences of the air diffuser orifices geometry on the airflow distribution in the enclosure. Integrating these orifices directly in a real scale air diffuser for a numerical study will result in a huge computational grid which will translate in huge computational resources and a much larger calculation time. The solution, in this case, was the numerical simulation of the airflow through small parts of the studied air diffuser. Later, the numerical results will be implemented as boundary conditions in the unidirectional diffuser of a numerical simulation that represents a real scale operating room (OR). In the current study two diffusers with different orifices were studied, one having circular („O”) and the other one lobbed („+”) orifices. The initial numerical model had 25 orifices on the diffuser, but because of the very large numerical grid resulted for the initial meshes (>35 million tetrahedral cells), a solution with only 4 orifices was chosen for this study. A mesh independency study was made for these two types of air diffusers. The numerical studies were made using RANS method, with SST k-ω turbulence model in steady state conditions. The numerical results obtained with the first step models showed very good agreement with the PIV stereoscopic experimental measurements.
Smart energy management of combined ventilation systems in a nZEB
Authors: Rey-Hernández Javier M. , Lorenzo González Sergio , San José-Alonso Julio F. , Tejero-González Ana , Velasco-Gómez Eloy , Rey-Martínez Francisco J.
Published: August 2019

The high energy consumption, attached to a high energy demand in buildings, has led the development of several research projects with the target of reducing the energy consumption in the buildings. As a result of this high consumption, the increased CO2 emissions that have been generated in recent years, have reached alarming levels, which is why it is necessary to reduce the environmental impact which we are contributing to our planet through the use of energy.

The European Directive on Building Performance (EPBD 2018/844/EU), recently updated, requires new buildings to be close to the Zero Energy Buildings (nZEBs), increasing the use of renewable energies on-site, and also highlight how to get to improve the cost-effective renovation of existing buildings with the introduction of building control and automation systems ( smart systems), as well as the energy savings and increase the efficiency of energy systems, by reducing CO2 emissions. The use of new renewable energy technologies integrated in buildings, with the aim of reducing the consumption of the facilities that all nZEB buildings must have, such as the ventilation system used as an Indoor Air Quality (IAQ) control technique.

In this study, the energy management of the enthalpy ventilation control system is analysed, where dynamic monitoring is going on in the building controlled through Supervisory Control And Data Acquisition (SCADA), in combination with different ventilation systems as free-cooling, heat recovery and geothermal energy of an Earth Air Heat eXchanger (EAHX), all of them as strategies implemented in a real nZEB building (LUCIA) located on the campus at the University of Valladolid, with the goal of improving energy efficiency in ventilation. In order to get this aims, monitoring data of several energy parameters (temperature, air velocity, air flow rate, enthalpy, etc.) are measurements, they allow us to perform a control of the combined ventilation systems to achieve a high IAQ and analyze an optimization of the energy efficiency of the all systems and to study of energy recovery and savings of carbon emissions that directly affect the reduction of the impact of climate change.

The results achieved are the energy efficiency of the building in ventilation and optimum system operation in cooling and heating mode. In addition, by controlling the ventilation, the IAQ of the nZEB building is improved.
Comparison of model identification techniques for MPC in all-air HVAC systems in an educational building
Authors: Merema Bart , Breesch Hilde , Saelens Dirk
Published: August 2019

In school and office buildings the ventilation system has a large contribution to the total energy use. A control strategy that adjusts the operation to the actual demand can significantly reduce the energy use. This is important in rooms with a highly fluctuating occupancy profile. However, a standard rule-based control is reactive, making the installation ‘lag behind’ in relation to the demand. A model predictive control (MPC) might be a solution. To implement an MPC control first a suitable model must be identified for reliable predictions of room temperature and CO2 concentration. For CO2 predictions three scenarios are proposed respectively counting camera, lecture schedule and motion sensor. Two model identification techniques are evaluated: ARX and RC models. For identifying the heating dynamics of the case study building the 3 state RC model showed a good performance, a 5 step ahead prediction on a 15 minute time interval indicated a RMSE of approximately 0.60 °C. The 3rd order ARX model indicated similar results, however the cross validation demonstrated that the RC model outperforms the ARX model. For CO2 predictions the counting scenario resulted in the most accurate n-step ahead predictions. The RMSE found for the RC model is at maximum 90 ppm while 140 ppm for the ARX model. RC models are recommended for modelling all-air HVAC systems attributed by the higher prediction accuracy over ARX models. In addition, these models still contain physical parameters compared to ARX models.
Numerical research on thermal performance of water-flow window as hospital curtain-wall
Authors: Li Chunying , Tang Haida , Ding Jianhua , Lyu Yuanli
Published: August 2019

Water-flow window can reduce indoor cooling load from direct solar radiation and preheat domestic hot water at the same time. It is quite suitable for hospital with patient wards and large demand of hot water, especially buildings with large area of glazing curtain-wall. Field measurement was carried out during July 2018 at a major comprehensive hospital in Shenzhen, and the inner surface of the four-storey west-facing glazing curtain-wall reached over 45.6oC in the daytime. The year-round energy-saving potential is investigated by applying water-flow window to the curtain-wall through programme simulation, with a pre-validated FORTRAN programme. The results show that the year-round solar energy utilization rate can reach as high as 9.4%, and the indoor thermal environment is better, compared with conventional window design. The preheated water can be used in wards for showering and help building energy conservation. Water-flow window has great potential for large-scale application within similar buildings.
The modelling of reverse defrosting cycles of air-to-water heat pumps with TRNSYS
Authors: Dongellini Matteo , Piazzi Agostino , De Biagi Filippo , Morini Gian Luca
Published: August 2019

The most widespread defrosting technique adopted by Air-Source Heat Pumps (ASHPs) during the heating season is Reverse Cycle Defrosting (RCD). In this paper a dynamic model of RCD, based on performance data provided by the heat pump manufacturer, designed for TRNSYS and with a core-structure suitable for commercial units, is presented. A defrost cycle is divided in three phases. First, the unit heating capacity is reduced as a linear function of the ice layer thickness (Pre-Defrost phase). Subsequently, the reverse cycle operating mode is modelled on the basis of the performance data given by the manufacturer (Defrost phase) and, finally, the heat pump performances are altered taking into account the higher surface temperature of the external coil after the reverse mode (Post-Defrost phase). Then, the influence of defrosting energy losses on the heat pump seasonal performance factor in sites characterized by different climatic conditions has been assessed. Results point out that the ASHP seasonal efficiency decreases of about 5% taking into account defrost energy losses; in addition, the influence of defrost cycles on the internal air temperature is studied by assessing under which conditions the indoor thermal comfort can be guaranteed even in presence of frequent defrost cycles.
Experimental Comparison of Radiant Ceiling Panels and Ceiling Panels Containing Phase Change material (PCM)
Authors: Bogatu Dragos-Ioan , Bourdakis Eleftherios , Kazanci Ongun Berk , Olesen Bjarne W.
Published: August 2019

Two commercially available ceiling panels, one metal and one gypsum incorporating microencapsulated PCM were compared experimentally to determine their limitations and ability to provide an adequate indoor thermal environment. The experiments took place from February to May 2018 in a climate chamber at the Technical university of Denmark. In total, seven scenarios were evaluated, five with active cooling, where the flow rate and solar heat gains were varied, and two without. Results showed that according to EN 15251:2007, the RCPs maintained the best indoor thermal environment for 91% of occupancy time in Category III – operative temperature between 22oC and 27oC, and 75% in Category II – operative temperature between 23oC and 26oC, for a 140 kg/h flow rate and the reference solar heat gains. Alternatively, the PCM panels maintained Category III for only 48% of the time, while only 30% in Category II for a 220 kg/h flow rate and the reference solar heat gains. The PCM panel presented the ability to store the heat for a later time. However, the PCM panels’ solution proved inadequate in terms of heat storage capacity, pipe positioning and thermal conductivity while improvements are required in order to employ them in new and renovated buildings.
Thermally Activated Concrete Slabs with Integrated PCM Materials
Authors: Millers Renars , Korjakins Aleksandrs , Lesinskis Arturs
Published: August 2019

As building codes are pushing towards higher energy efficiency and the arrival of nearly Zero Energy Building (nZEB) requirements for all new buildings are just around the corner the need for alternative, high efficiency heating and cooling solutions for nZEB’s is greater than ever. Also as experience with renewable energy sources has proven the energy demand and energy generation rarely overlaps and it does not allow to fully utilise some renewable energy sources. This is a simulation study that focuses on integrated cooling and energy storage system utilising phase-change materials (PCM). Several types of thermally activated slabs with different PCM thicknesses were simulated in order to find the most optimal PCM thickness with melting point temperature that can support passive cooling methods based on adiabatic cooling principles. Two calculation tools were used for the study – IDA ICE 4.8 and U-NORM 2012-2 to calculate the properties of the slabs and potential of application in well insulated residential building in Baltic climate. The results showed that the optimal thickness for thermally activated PCM layer (large flat containers) range from 25 mm to 90 mm, and for layers with no thermal activation – 180 mm and more. Moreover the results show that apart from energy storage the thermally activated panel can increase thermal comfort conditions.
Design methodology for combined production and distribution for domestic hot water and space heating
Authors: Verhaert Ivan
Published: August 2019

As local heat demand is reducing due to an increased insulation rate, investing in sustainable heat production becomes less interesting. Nevertheless a substantial demand of heat remains in which the thermal energy needed for the generation of domestic hot water grows relatively in importance. In the last two years standards to size production and distribution systems were revised and methods based on tap patterns were elaborated. Nevertheless, some aspects were not covered yet, e.g. how to deal with decentralized storage and how to use these results and new insights in combined heating systems, taking into account that modifications in standards for both space heating and domestic hot water installations are reducing the oversizing. In this paper, first some critical points of attention due to this evolution are illustrated with a case example. Next it is shown how different rules of thumb often developed by different manufacturers deal with these aspects, but lacking however compatibility with existing standards and/or new insights.

Finally, a methodology is proposed and illustrated how to size distribution and production systems for combined heating systems taking into account central and decentralized storage and different kind of end users. The method can be used to size heating systems in collective housing or in district heating networks.
Moisture Recovery – A Dynamic Modelling Approach
Authors: Kremer Martin , Mathis Paul , Müller Dirk
Published: August 2019

With rising insulation standards, the use of mechanical ventilation, especially in non-residential buildings, is becoming increasingly relevant. To ensure thermal comfort and avoid health problems for people in the room, cost- and energy-intensive humidification of the supply air is necessary. The use of moisture recovery systems can thus significantly reduce the energy consumption of ventilation systems. Despite this energy-saving potential, moisture recovery systems are rarely used in ventilation systems.

To forecast the efficiency of moisture recovery systems in partial load operation and under different climatic conditions, a dynamic model of a membrane-based enthalpy exchanger was developed in the object-oriented modelling language Modelica. The model is based on the solution diffusion model, a quite common approach. In contrast to the models found in the literature, the sorption process is not assumed to be in equilibrium state. Rather, as a first approach the membrane’s permeance, consisting of the solubility and diffusion coefficient, is modelled with a linear dependency on the moisture difference between the two incoming airflows.

A parameter fitting has been carried out with experimental data to determine the unknown material parameters. The model containing the fitted parameter set was validated using different experimental data.
A review of total volume environment and individually controlled micro-environment
Authors: Zhao Weixin , Kosonen Risto , Kilpeläinen Simo , Lestinen Sami
Published: August 2019

Indoor environment has great effects on the health, comfort, and performance of occupants in modern buildings. The energy used for ventilating of buildings is substantial. However, ventilation based on total volume air distribution in spaces is not always an energy efficient way to provide high-quality indoor environments. Recently, individually controlled ventilation, which is designed to supply clean air where, when, and as much as needed, makes it possible to efficiently achieve high-quality indoor environment while reducing energy use. The personalized solutions generate a micro-environment that covers the space where the user spends a relatively long time. This review based on a number of experimental and numerical studies on total volume ventilation, zonal ventilation and personalized ventilation to assess the most suitable methods for indoor environment. Performance in terms of thermal comfort, air quality and energy efficiency are examined. In this study, different ventilation systems are classified according to specific requirements and assessment procedures. Finally, a discussion on the application and benefits of these ventilation is conducted and gives a direction for further investigation. The analysis results form a basic framework regarding the application of personalized ventilation in future.
Evaluation of Four Models for Predicting Thermal Sensation in Chinese Residential Kitchen
Authors: Zhou Xiaojie , Liu Sumei , Liu Xuan , Lin Xiaorui , Qing Ke , Zhang Weizhen , Li Jian , Dong Jiankai , Lai Dayi , Chen Qingyan
Published: August 2019

Thermal environment in residential kitchen in China is transient and non-uniform and with strong radiation asymmetry from gas stove. Due to the complexity of kitchen thermal environment, it is not sure if previous thermal comfort models can accurately predict the thermal comfort in residential kitchens. In order to evaluate if existing thermal comfort models can be applied for Chinese kitchens, this investigation conducted human subject tests for 20 cooks when preparing dishes in a kitchen. The study measured skin temperatures of the cooks and environmental parameters and used questionnaires to obtain their thermal sensation votes at the same time. The actual thermal sensation votes were compared with the predicted ones by four thermal comfort models: predicted mean vote (PMV) model, dynamic thermal sensation (DTS) model, the University of California at Berkeley (UCB) model, and the transient outdoor thermal comfort model from Lai et al. The results showed that all the models could predict the trend of the thermal sensations but with errors. The PMV model overpredicted the thermal sensations. The UCB and Lai’s models showed a slower change in thermal sensation votes (TSV) after turning on the stove. The DTS model was more accurate than the others in predicting the mean thermal sensation, but with a large variation in predicting individual thermal sensation votes. A better thermal comfort model should be developed for Chinese residential kitchens.
Impact of room airflow interaction on metabolic CO2 exposure
Authors: Keli Athanasia , Melikov Arsen K. , Bivolarova Mariya P. , Mustakallio Panu
Published: August 2019

CFD simulations were performed to investigate occupants’ exposure to metabolic CO2 in a room with mechanical ventilation. A meeting room occupied by six adult people performing sedentary activity was simulated. Five of the six occupants were simulated to exhale air with realistic CO2 content, while one occupant was inhaling, i.e. the exposed occupant. Both exhalation and inhalation were simulated with constant flow rates. Two air distribution patterns were considered, mixing and displacement air distribution, each was combined with chilled ceiling, as summer conditions were simulated. For both air distribution patterns, the influence of solar gain of 200 W, which was simulated as heated vertical surface (window), and the distance between the occupants facing each other were studied. The simulation results revealed the importance of buoyancy flows generated by heated vertical surfaces for the pollution distribution. It was found out that compared to the case without solar heat gain, the presence of solar gain increased the inhaled CO2 level by 26.9 % in the case of displacement ventilation, while it reduced the exposure by 4.5 % when the outdoor air was distributed by mixing ventilation. The distance between the occupants facing each other did not affect considerably the exposure.
European Study on heat recovery in non-residential buildings
Authors: Kaup Christoph , Knissel Jens
Published: August 2019

The HR (heat recovery) is generally assessed very positively from a business and economic point of view. In order to demonstrate this development, a first study will evaluate around 5,000 design data elements. First, the designs are evaluated with the question of how the key efficiency characteristics of the HR have changed throughout the course of the years 2014 to 2017. Afterwards, all relevant design files are subjected to an economic efficiency calculation under defined conditions, in order to determine the potential for a multidimensional optimization. Furthermore, the impact of the EU 1253/2014 benchmarks from 2020 onwards will also be examined. In order to demonstrate this development in europe, a second study will evaluate around 3,300 design data elements. First, the designs are evaluated with the question of how the key efficiency characteristics of the HR have changed throughout the course of the years 2015 to 2018. Primary, all relevant design files are subjected to an economic efficiency calculation under defined conditions, in order to determine the potential for a multidimensional optimization. Then, the impact of the EU 1253/2014 benchmarks from 2020 onwards will also be examined. The influence of the climate is thereby also taken into account by examining three European sites (North-South view). At the same time, the influence of the run time of the systems will be calculated. Ultimately, the analyses will provide recommendations for the future design of the Ecodesign regulation.
Finnish design ventilation rates for residential buildings
Authors: Säteri Jorma , Seppänen Olli , Ahola Mervi
Published: August 2019

Implementation of EU directives has forced EU member countries to revise the building regulations related energy efficiency. The 2017 revision of the building codes is due to the requirement set in the EPBD 2010 for all new buildings to be nearly zero buildings by 2020. The Finnish Ministry of the Environment (in charge of building regulations) invited FINVAC Federation of Finnish HVAC Associations to revise the guidelines values of ventilation rates as part of the nearly zero energy building regulations. At the same time, the Finnish Society of Indoor Air Quality and Climate updated its voluntary Classification of Indoor Environment. Several methods were used in the study to collect information and develop the new guideline values. European studies, such as HEALTHVENT, and relevant CEN standards were taken into consideration in drafting the design ventilation rates. Existing legislation on housing conditions gave the minimum levels and, finally, the recommended values were defined using expert interviews, workshops and public review process. Earlier studies had indicated that earlier design ventilation rates were too high for small apartments. Ventilation rates were considered too low for homes of elderly people and residential kitchen hoods, and some larger apartments. Furthermore, the balance of outdoor and exhaust air flows needed revision due to the improved tightness of the building envelope. Energy efficiency and avoidance of draught and noise were also taken into account. This paper presents the numeric values of the ventilation rates in the new building regulations and the design guidelines supporting them.
Revised Finnish classification of indoor climate 2018
Authors: Ahola Mervi , Säteri Jorma , Sariola Laura
Published: August 2019

The Finnish Society of Indoor Air Quality and Climate (FiSIAQ) introduced a Classification of Indoor Climate, Construction Cleanliness, and Finishing Materials in 1995. The Classification of Indoor Climate has been revised to meet the new Decree on indoor air quality and ventilation, European standards and experience from users of the classification. The most significant change is that target values for concentration and the in/out ratio of fine particles have been added. Other adjustments have been made to ensure good indoor environment and energy efficiency, but with reasonable investments. The criteria for emissions from building material and furniture were also updated. The Building Information Foundation RTS sr has run the M1-labelling of building products since 1996. The voluntary approach has been proven to improve the IAQ in new buildings and to reduce emissions from building materials. The Classification of Indoor Environment 2018 is integrated part of the new RTS Environmental Classification system.