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Heat transfer coefficient (HTC) was experimentally measured for saturated and subcooled pool boiling of binary mixtures of water and glycerin. Saturated boiling was studied for mixtures with water mass fractions ωw from 100% to 60% on horizontal flat nickel-plated surfaces at heat fluxes from 50 to 650kWm−2 at atmospheric pressure. Subcooled boiling was investigated in the range of subcooling from 0 to 30K at heat fluxes of approximately 250, 450 and 650kWm−2. It was found that mixture effects have a significant impact on saturated boiling HTC even for mixtures with very low content of glycerin as significant drops of HTC were observed for subtle changes in composition for mixtures of high ωw. Measured HTC was successfully correlated with the combination of Yagov (1999) and Inoue and Monde (2009) correlations with a mean relative error of 12%. A simple empirical HTC correlation is also proposed. For subcooled boiling, developed subcooled boiling regime was reached for all investigated heat fluxes. For this regime, correlations, which were able to predict HTC for saturated boiling, were employed to predict subcooled boiling HTCs for all investigated concentrations, heat fluxes and subcoolings. Effect of subcooling and effect of liquid composition on total HTC were of the same importance for mixtures with higher water content. With the increase in concentration of glycerin in the mixture, decrease in total HTC with increasing subcooling became more significant.

Thermal water discharge within the gravity-driven groundwater flow system in the Alps and other similar areas around the world may be hidden in Quaternary deposits which, in these regions, often cover the regional aquifer. When thermal water drains into Quaternary deposits, the mixing of the deep thermal component and the cold shallow groundwater forms a thermal plume that extends parallel to the main groundwater flow in shallow system. In the Bled case study in Slovenia, the thermal water discharges from carbonate rocks into Quaternary glaciofluvial sediments, and as the Toplice spring at a rate of 5 l/s at an average temperature of 21.5 °C. Knowing the spatial extent and intensity of thermal outflow is essential to decision making related to the development and protection of this renewable resource. By approximating the thermal water outflow from a discharge zone as a planar source, a planar advective heat transport model can be used to evaluate its geometry and quantify rates. An analytical procedure follows rough assumptions leading to conservative results. Moreover, a numerical model using the FEFLOW code was applied for comparison with the simulations of the analytical model. The heat transport model was based on measured hydraulic parameters (e.g. groundwater levels) and borehole temperatures as well as on-site and international literature (e.g. dispersivity, thermal conductivity). Nine scenarios were applied accounting for different dimensions of the heat source and compared to the results of numerical simulations. Each scenario was verified by calculating the relative error between the analytical models and the measured borehole temperatures. The results confirm that the main outflow of thermal water can be determined using planar geometry, and is 200–300 m wide. The height of the thermal outflow zone is approximately 25 m, corresponding to the expected thickness of the direct contact between the fractured dolomite and the shallower Quaternary aquifer. Using the proposed widths and depths, the hidden natural thermal outflow rates are estimated at 57–86 l/s.

Bubble removal from a solid surface is of significant importance to many technical processes and applications. In addition to the conventional buoyancy-aided bubble removal, there is also a passive strategy to remove bubbles from a solid surface via coalescence. However, likewise several processes, the coalescence-induced removal of bubbles from the solid surface is masked by the dominant buoyancy, hence, difficult to observe in terrestrial conditions. Microgravity condition offers a unique opportunity to investigate such phenomenon in great detail that can significantly improve our fundamental understanding. In this work, we report coalescence-induced jumping of isolated vapor bubbles from the heated substrate during shear flow in microgravity condition. We show that, similar to the coalescence-induced jumping droplets, when two bubbles coalesce, the resulting big coalesced bubble jumps from the substrate due to the conversion of excess surface energy into the translational kinetic energy, which provides the requisite initial velocity for jumping. Jumping of bubbles over a wide range of bubble size (post-coalescence radius ≈0.9–3.4 mm) is observed. Bubbles oscillate continuously while rising through certain height post-coalescence. We perform force balance and scaling analysis to develop a model to predict the maximum jumping height of bubbles. We show that the jumping height is strongly related to the bubble size and the non-dimensional Ohnesorge number, which captures the role of fluid properties governing the coalescence. The physical insight presented in this work has implication for the design of energy systems and microfluidic devices for the earth and space-based applications.

In recent years, the field of biomass gasification as a method of transforming biomass into a more useable gaseous fuel experienced expedited development since it represents a prominent way to achieve sustainability goals and targets set by the Paris accord and, more recently, the European Green Deal. The use of natural gas is projected to reduce with the transition toward exploitation of renewable gas, while a new area of hydrogen applications is also emerging. However, with uncertain production of current processes, and consumption patterns seen on the market, an opportunity for a new flexible process exists. This article investigates a concept process design of sorption-enhanced gasification (SEG) based on calcium looping. Aspen Plus simulation software was used to develop and simulate the process models for flexible production of bio- SNG or bio-H2. The process parameters can be manipulated to either achieve a high-purity bio-H2 (>96 mol%) or high-purity bio-SNG (>95 mol%), as well as any other combination of the two main products. The concept process is based on a low-pressure, low-temperature dual-fluidized bed reactor with steam as a gasifying agent and an additional downstream Sabatier process reactor to achieve high CH4 contents. The simulated process achieves process efficiency of up to 62.2%LHV and 78.0%LHV for H2 and CH4 production, respectively, with production yields reaching 0.112 kg H2/kg BM and 0.23 kg CH4/kg BM. These values were validated and benchmarked against comparable process designs, and the performance of the proposed process was found to be on par or superior. Overall, the proposed process design exhibits clear benefits of calcium looping gasification, with high process efficiency, negligible NOx, SO2, and H2S content, and high flexibility. Therefore, the proposed process addressed and successfully solved some of the key challenges of achieving viability of a gasification plant on a commercial scale.

High-temperature phase relations in the La2O3–TiO2–Nb2O5 ternary system were investigated at 1290 °C using SEM, EDS and XRD, and a subsolidus phase equilibrium diagram was constructed. It was demonstrated that the addition of the La1/3NbO3 to the La2O3:3TiO2 mixture completely stabilizes a perovskite-La2/3TiO3 compound, which is otherwise not stable at stoichiometric composition. On the other hand, a mixture La2O3:TiO2 =1:3 dissolves in La1/3NbO3 up to 15 mol% TiO2. Moreover, a newly defined composition of compound La30Ti16Nb4O87 formed in the La2O3-rich part of the system and a solid solution La3Ti5Nb10O39.5–La2Ti2Nb8O27 were proposed. In the binary subsystem LaTiNbO6-La0.462Ti0.386Nb0.614O3, the components exhibit opposite temperature dependence of resonant frequency in the microwave frequency range. Thus, the dielectric properties of the prepared ceramics can be tailored by varying the component concentration and thermally stable dielectric properties can be achieved for a composition with a LaTiNbO6/La0.462Ti0.386Nb0.614O3 molar ratio of 0.27.

Increased cooling requirements of many compact systems involving high heat fluxes demand the development of high-performance cooling techniques including immersion cooling utilizing pool boiling. This study presents the functionalization of copper surfaces to create interfaces for enhanced pool boiling heat transfer. Three types of surface structures including a crosshatch pattern, shallow channels and deep channels were developed using nanosecond laser texturing to modify the surface micro- and nanomorphology. Each type of surface structure was tested in the as-prepared superhydrophilic state and superhydrophobic state following hydrophobization, achieved through the application of a nanoscale self-assembled monolayer of a fluorinated silane. Boiling performance evaluation was conducted through three consecutive runs under saturated conditions at atmospheric pressure utilizing water as the coolant. All functionalized surfaces exhibited enhanced boiling heat transfer performance in comparison with an untreated reference. The highest critical heat flux of 1697 kW m−2 was achieved on the hydrophobized surface with shallow channels. The highest heat transfer coefficient of 291.4 kW m−2 K−1 was recorded on the hydrophobized surface with deep channels at CHF incipience, which represents a 775% enhancement over the highest values recorded on the untreated reference. Surface microstructure was identified as the key reason for enhanced heat transfer parameters. Despite large differences in surface wettability, hydrophobized surfaces exhibited comparable (or even higher) CHF values in comparison with their hydrophilic counterparts, which are traditionally considered as more favorable for achieving high CHF values. A significant reduction in bubble departure diameter was observed on the hydrophobized surface with deep channels and is attributed to effective vapor entrapment, which is pointed out as a major contributing reason behind the observed extreme boiling heat transfer performance.

Naslov diplomskega dela je Stili navezanosti in iskanje psihosocialne podpore in pomoči. V delu želim ugotoviti, ali obstaja povezava med določenim stilom navezanosti in iskanjem psihosocialne podpore in pomoči. V teoriji sem se dotaknila teorije navezanosti, razvoja stilov navezanosti od otroštva do odraslosti. Prav tako sem pisala o potrebah po psihosocialni podpori in pomoči, o strokovnjakih, ki nudijo takšno pomoč, o nekaterih organizacijah, ki delujejo na tem področju, in o povezavi med psihosocialno podporo in pomočjo ter stili navezanosti. Vzorec v kvantitativni raziskavi je bil neslučajnostni priložnostni in je vključeval 145 polnoletnih oseb, ki so v času izvedbe raziskave živele v Sloveniji. Odgovore na raziskovalna vprašanja sem zbrala z uporabo anketnega vprašalnika v spletni aplikaciji Arnes 1ka. Z raziskavo sem ugotovila, da je več tistih, ki potrebujejo psihosocialno podporo in pomoč, kot pa tistih, ki nikoli ne potrebujejo takšne podpore in pomoči. Delež tistih, ki nikoli ne poiščejo psihosocialne podpore in pomoči, ker je nikoli ne potrebujejo, je v največji meri pri anketiranih z varnim stilom navezanosti, nato pri anketiranih z odklonilno-izogibajočim stilom navezanosti, sledijo jim anketirani s plašljivo-izogibajočim stilom navezanosti in nazadnje še anketirani s preokupiranim stilom navezanosti. Delež anketiranih, ki nikoli ne poiščejo psihosocialne podpore in pomoči, čeprav čutijo, da bi jo potrebovali, je največji pri anketirancih s preokupiranim stilom navezanosti, nato jim sledijo anketiranci s plašljivo-izogibajočim stilom navezanosti, nato anketiranci z odklonilno-izogibajočim stilom navezanosti, najmanjši delež pa je pri anketirancih z varnim stilom navezanosti. Delež tistih, ki še nikoli niso prejemali psihosocialne podpore in pomoči, je največji pri anketirancih z odklonilno-izogibajočim stilom navezanosti. Anketiranci z varnim stilom navezanosti, ki ne poiščejo psihosocialne podpore in pomoči, čeprav bi jo potrebovali, so največkrat odgovorili, da je razlog, da nimajo dovolj denarja. Enak razlog je tudi pri anketiranih, ki imajo plašljivo-izogibajoč stil navezanosti. Pri anketiranih s preokupiranim stilom navezanosti izstopa poleg razloga, da nimajo dovolj denarja, tudi razlog, da ne vedo, na koga se obrniti. Pri anketiranih z odklonilno-izogibajočim stilom navezanosti, ki ne poiščejo pomoči, čeprav bi jo potrebovali, je razlog največkrat strah. Anketiranci, ki imajo preokupiran, varen ali plašljivo-izogibajoč stil navezanosti, se največkrat v čustveni stiski, kot je stres, odzovejo s pogovorom s partnerjem. Anketiranci z odklonilno-izogibajočim stilom navezanosti pa se pogovorijo s partnerjem, jokajo ali pa se zamotijo z drugimi dejavnostmi, ki jim pomagajo odmisliti problem. Med anketiranci s plašljivo-izogibajočim, varnim ali preokupiranim stilom navezanosti je več tistih, ki potrebujejo verbalno spodbudo bližnjih kot pa druge vrste podpore, da bodo poiskali psihosocialno podporo in pomoč, ko jo potrebujejo. The title of my paper is Attachment Styles and Seeking Psychosocial Support and Help. As the title suggests, I wanted to find out if there is a connection between people with a certain attachment style and their tendency to seek psychosocial support and help. In the theoretical part, I presented the attachment theory and the development of attachment styles from childhood to adulthood. I also wrote about the need for psychosocial support and help, professionals who provide such support, some organizations working in this field, and the connection between psychosocial support and help on the one side and attachment styles on the other. The sample of my quantitative research was non-random, ad hoc sample, including 145 adults who lived in Slovenia when the research was being conducted. I gathered their answers using a survey in the Arnes 1ka web application. Through research, I found that there are more of those who need psychosocial support and help than those who have never needed such support and help. The share of those who have never sought psychosocial support and help because they do not need it is the highest among respondents with a secure style of attachment, followed by respondents with a dismissive style of attachment, after them respondents with a fearful-avoidant style of attachment and finally respondents with a preoccupied style of attachment. The share of respondents who have never sought psychosocial support and help even though they feel they need it is the highest among respondents with a preoccupied style of attachment, followed by respondents with a fearful-avoidant style of attachment, after them respondents with a dismissive attachment style and finally respondents with a secure attachment style. The share of those who have never received psychosocial support and assistance is the highest among respondents with a dismissive style of attachment. Respondents with a secure attachment style who have not sought psychosocial support and help even though they need it most often stated that the reason for that is their lack of money, which also applies to respondents who have a fearful-avoidant style of attachment. Respondents with a preoccupied style of attachment who have not sought psychosocial support and help even though they need it most often stated that they have done so because they do not have enough money or they do not know who to turn to. The reason that respondents with a dismissive style of attachment have not sought help even though they need it is most often fear. Respondents who have a preoccupied, safe, or fearful-avoidant style of attachment are most likely to respond to emotional distress such as stress by talking to a partner, whereas respondents with a dismissive style of attachment talk to their partner, cry, or find a distraction in other activities, which help them forget about the problem. Respondents with a fearful-avoidant or preoccupied style of attachment are more likely to need verbal encouragement from their loved ones than other types of support to seek psychosocial support and help when they need it.

V svojem diplomskem delu sem se osredotočila na raziskovanje socialnih mrež stanovalcev Doma starejših občanov Grosuplje. V teoretičnem delu sem zbrala nekaj definicij socialnih mrež, navedla različne vrste, opisala velikost mreže in povezave demografskih dejavnikov s socialnimi mrežami, opisala socialno oporo in socialni kapital in naslovila temi samote in osamljenosti. Na koncu teoretičnega dela sem predstavila Dom starejših občanov Grosuplje, kjer sem tudi izvedla raziskavo. V empiričnem delu sem najprej predstavila številčne podatke o obiskih, ki so jih imeli stanovalci v avgustu in septembru. Na podlagi zbranih podatkov sem s pomočjo kvotnega vzorca neslučajnostno izbrala osem stanovalcev, s katerimi sem izvedla intervjuje. Vprašanja, ki sem jih postavila, so bila vezana na to, s kom so se družili pred prihodom v Dom, kdo so pomembne osebe v njihovem življenju, na koga se obračajo, ko kaj potrebujejo, kdo sestavlja njihovo družino, kakšna je bila njihova izvorna družina, kakšne odnose imajo s stanovalci Doma, ali se udeležujejo dejavnosti, kaj jim pomenijo obiski, ali uporabljajo telefon, s kom imajo stike, se počutijo osamljeno itd. Ugotovila sem, da največji delež obiskovalcev predstavlja ožja družina ter da je število obiskovalk večje od števila obiskovalcev. Stanovalci ob obiskih doživljajo pozitivna čustva in so večinoma z njihovim številom zadovoljni. Socialna mreža stanovalcev se je po prihodu v Dom povečala, saj socialno mrežo sestavljajo še stanovalci in zaposleni. Socialno oporo jim v največji meri daje ožja družina, sami pa socialno oporo največkrat dajo v obliki druženja. Raziskava je pokazala, da na osamljenost lahko gledamo kot na subjektivni fenomen, saj večje število alterjev v socialni mreži še ne pomeni manjšega občutka osamljenosti, tudi za tiste stanovalce z manjšo socialno mrežo ni nujno, da so bolj izpostavljeni osamljenosti. Vloga socialne delavke v povezavi s socialnimi mrežami je, da je tudi sama predstavljena kot alter v socialni mreži stanovalcev, pomembno vlogo ima pri vključitvi stanovalcev ob prihodu v Dom, nanjo pa se obračajo stanovalci brez telefona, ki jim ga posodi in s tem zagotovi, da imajo lahko stik z alterji svoje socialne mreže. Ugotovila sem, da predhodni kraj bivanja ni v bistveni povezavi s socialnimi mrežami po prihodu v Dom, ravno tako ne tip sobe, v kateri so nastanjeni stanovalci. Rezultati raziskave so uporabni predvsem za zaposlene v Domu starejših občanov Grosuplje, ker bodo dobili boljši vpogled v pomembnost socialnih mrež njihovih stanovalcev in lahko po potrebi prilagodili način dela z njimi. The thesis focuses on the social networks of the residents of the Home for the elderly in Grosuplje. The theoretical part includes definitions of social networks, with different types, and the description of the network size, connections between demographic factors and social networks, social support and social capital, with an emphasis on the topics of solitude and loneliness. It concludes with the presentation of the Home for the elderly in Grosuplje, where the research was performed. The empirical part begins with the presentation of numerical data on the visits the residents received in August and September. Based on the collected data, eight residents were selected, using non-probability quota sampling, for the interviews. The questions asked concerned the persons they were associating with before arriving in the Home, the important people in their lives, who they turn to when they need something, who is a part of their family, what was their family of origin like, what are their relationships with the Home residents, whether or not they engage in activities, what do visits mean to them, do they use phones, with whom they keep in touch, do they feel lonely, etc. It was found that the majority of visitors include their immediate families and that the number of female visitors is greater than the male. The residents have positive emotions relative to the visits and are mostly content with their number. The residents’ social network expanded after arriving in the Home, as it now also includes the other residents and the Home employees. Their social support comes, for the most part, from their immediate families, while they themselves offer social support mainly in the form of socializing. The research revealed that loneliness can be viewed as a subjective phenomenon, given that a greater social network does not necessarily mean less feelings of loneliness inversely, the residents with a smaller social network are not necessarily lonelier. The role of a social worker, in connection with social networks, is being a part of the residents’ social network, playing an important role in introducing the residents to the Home life upon their arrival and offering assistance by letting the residents without a phone use hers, which allows them contact with the persons from their own social network. It was also found that the previous place of residence is not significantly relevant to the residents’ social networks after they arrive in the Home, neither is the type of room where they reside. The research results will be especially useful for the employees of the Home for the elderly in Grosuplje, giving them better insight into the importance of their residents’ social networks and allowing them to adapt their work with them, if necessary.

Heat exchanger performance is significantly reduced in the presence of impurities in one or both fluid streams, frequently by deposits of inversely soluble salts. Accordingly, immense efforts were and still are spent to combat, predict, and investigate such fouling problems to mitigate the reduction of heat transfer performance. In this study, calcium carbonate crystallization fouling in a corrugated plate heat exchanger was investigated. Fouling was monitored using temperature and flow measurements, and, for the first time, coupled with infrared thermography observations. We show a clear and measurable local difference between clean and fouled conditions, regardless of operating conditions. Infrared measurements of temperature permit conclusions about flow distribution and the spatial location of areas with severe fouling. Compared to the clean state, completely skewed isotherms after fouling point out channel blockage and flow obstructions, resulting in large scale flow re-distribution within the channel. The presented results exhibit a clear benefit of this approach for heat exchanger fouling studies and serve as a foundation for future research of dynamic operation, transient response, and computational models.

While renewable energy sources enjoy high public support, projects are rarely implemented without opposition. The term energy landscapes indicates that landscape change is amongst the most frequent issues. This study researched lay people’s perceptions of landscapes changed by solar power plants. The first objective was to discover how likely solar power plants are to be noticed in the landscape. The second objective was to determine the associations observers make when spotting a solar power plant. The data was collected by participatory photography and focus groups. Participants visited six solar power plants. The results show that they are highly noticeable and contentious objects. Participants who understood the landscape as a rural idyll disapproved of solar power plants, while for those who perceived the landscape through a utilitarian narrative, the (mis)fit of the solar power plant depended on its relation to the surrounding landscape structure. Landscape degradation was contrasted with low-carbon energy and developmental benefits. The results provide evidence on the interdependence of visual and non-visual factors and suggest improvements in planning and design of solar power plants. While the method gives a rich in-depth insight into landscape perception, it is also context dependent and needs further research to obtain more generalisable results.

Although each landscape has its own identity, only some of them are recognized as nationally important because of their cultural and natural values and their contribution to national identity. In Slovenia, these landscapes are listed in the national Spatial Development Strategy (adopted in 2004). However, this list was neither supported by implementation instruments nor integrated in any conservation or management policy documents and was poorly integrated into spatial plans. The aim of this research was to renew the methodology for identifying landscapes of national importance. The methods included in-depth interviews with experts, an online questionnaire, participatory workshops, and field visits. The questionnaire results showed that only eight landscapes from the original list of 62 were explicitly recognized as nationally important, which confirmed the hypothesis that the initial method was not transparent and that the criteria were biased. The proposed approach included the following criteria: (1) representativeness, (2) the quality of the landscape features, and (3) the cultural and scientific value. The methodology was accompanied with the list of landscape features and landscape types that are important for Slovenian national identity recommendations for implementing the method on national, regional, and local levels and the general guidelines for spatial planning and management of these landscapes.

Growing world population and increasing population density are leading to increasing waste production with biological waste amounting to several billion tonnes annually. Together with the increasing need for renewable energy sources, waste-to-biogas conversion as a prime example of waste-to-energy technology represents a facile way of solving two problems simultaneously. This review aims to address the recent progress in the field of waste-to-biogas technology, which is lately facing intensive research and development, and present the current status of this waste treatment method both in technological and legislative terms. The first part provides an overview of waste and waste management issues. This is followed by a detailed description of applicable waste-to-energy (WtE) technologies and their current implementation in selected European countries. Moreover, national energy and climate plans (NECPs) of selected EU Member States are reviewed and compared with a focus on implementation of WtE technologies. In a further section, biogas production from waste around the world is reviewed and compared country wise. Finally, an outlook into the future of WtE technologies is provided alongside the conclusions based upon the reviewed data.

The purpose of this study was to investigate the droplet size obtained with a three-channel spray nozzle typically used in fluid bed devices and to construct a semi-empirical model for prediction of droplet size. With the aid of a custom-made optical method concept, the impact of the type of polymer and solvents used through dispersion properties (viscosity, density, and surface tension), dispersion flow rate, atomization pressure, and microclimate pressure on droplet size was investigated. A semi-empirical model with adequate predictability for calculating the average droplet size (R2 = 0.90, Q2 = 0.73) and its distribution (R2 = 0.84, Q2 = 0.61) was constructed by employing dimensional analysis and design of experiments. Newtonian and non-Newtonian dispersion and process parameters on laboratory and on production scale were included, thereby enabling constant droplet size irrespective of the scale. Based on the model results, it would be possible to scale-up the atomization process (e.g., coating process) from laboratory to production scale in a systematic fashion, regardless of the type of solvent or polymer used. For the system investigated, this can be performed by understanding the dispersion properties, such as viscosity, density, and surface tension, as well as the following process parameters: dispersion flow rate, atomization, and microclimate pressure.

Acetylenedicarboxylic acid dihydrate (ADAD) represents a complex with strong hydrogen bonding between the carboxylic OH and the water molecule. An X-ray re-examination of the ADAD crystal structure confirms the O…O distance of the short hydrogen bonds, and clearly shows different bond lengths between the two oxygen atoms with respect to the carbon atom in the carboxyl group, indicating a neutral structure for the complex. The neutral structure was also confirmed by vibrational spectroscopy, as no proton transfer was observed. The diffraction studies also revealed two polymorph modifications: room temperature (α) and low temperature (β), with a phase transition at approximately 4.9 °C. The calculated vibrational spectra are in satisfactory agreement with the experimental spectra. A comparison of the structure and the vibrational spectra between the ADAD and the oxalic acid dihydrate reveals some interesting details. The crystal structures of both crystal hydrates are almost identical; only the O…O distances of the strongest hydrogen bonds differ by 0.08 Å. Although it was expected that a larger O…O spacing in the ADAD crystal may significantly change the infrared and Raman spectra, especially for the frequency and the shape of the acidic OH stretching vibration, both the shape and frequency are almost identical, with all subpeaks topped on the broad OH stretching vibration. The O…O distance dependent are only in- and out-of-plane OH deformations modes. The presence of polarons due to the ionized defects was not observed in the vibrational spectra of ADAD. Therefore, the origin of the broad OH band shape was explained in a similar way to the acid dimers. The anharmonicity of a potential enhances the coupling of the OH stretching with the low-frequency hydrogen bond stretching, which, in addition to the Fermi resonance, structures the band shape of the OH stretching. The fine structure found as a superposition of a broad OH stretching is attributed to Davydov coupling.

International audience; This publication lays the foundation for the description of the Multiscale Boiling Experiment, which was conducted within two measurement campaigns on the International Space Station between 2019 and 2021. The experiment addresses fundamental questions about two-phase heat transfer during boiling processes. For this purpose, single or few subsequential bubbles are selectively ignited on a heated substrate using a short laser pulse. A detailed investigation of the phenomena is possible, as the boiling process is temporally slowed down and spatially enlarged in microgravity. Within the Multiscale Boiling Project, the undisturbed growth of the bubbles, the influence of a shear flow, and the influence of an electric field are investigated within the same test facility using FC-72 as working fluid. Within the project, thirteen research groups from eight countries are collaborating. Over 3000 data sets have been generated over an 11-month measurement period. In the context of this publication, besides the motivation and necessity of such investigations, the basic structure of the experiment, the objectives of the investigations, and the organization are described. Finally, first results of the investigations are presented. Therefore, this publication has the primary aim to serve as a basis for many further planned publications and present the project as a whole.

We present the results of a study aimed at investigating the effects of electric fields on quasi-static bubble departure dynamics during pool boiling of perfluorohexane (FC-72) in microgravity conditions. Analysis was performed through an alternative formulation of the bubble momentum balance in which the contribution of non-uniform electric stress distributions at the bubble interface can be quantified through high-speed video measurements without having to numerically solve the laws of electrostatics. Data used in this study were obtained in the scope of the Multiscale Boiling Project, which included advanced single bubble growth experiments performed aboard the International Space Station. Our results confirm that bubble departure counterintuitively begins before the force resulting from electric stresses starts to pull the bubble up from the wall. When this occurs, it is shown that the shrinking process of the contact line accelerates, in agreement with known theoretical results. It is concluded that the electric force is essentially determined by the electric stress distribution at the bubble cap above the contact area. Furthermore, we show that the electric stress at the bubble interface is also responsible for the increase in bubble internal overpressure, which explains the early departure of the bubble while increasing the intensity of the electric field. The results of this study provide an important step in achieving a more comprehensive understanding of the bubble behavior at the heated surface in the presence of an electric field, which is essential to optimally design electrodes and two-phase heat transfer devices for future space applications.