High Thermal Inertia Research Articles

Sustainable Design of a Tiny House: Using a Life Cycle Assessment Approach to Compare the Environmental Performance of Industrial and Earth-Based Building Systems

The increased concerns about climate change, diminishing natural resources, and environmental degradation call for deep research into new environmentally friendly building systems that use natural or recycled materials. The article presents an assessment of the environmental and climatic benefits associated with the construction of a tiny house made of quincha, a building system based on a wooden structure filled with locally sourced earth and straw. The tiny house is located in the Elqui Valley, in the Chilean region of Coquimbo, and it is designed to be compact, functional, comfortable, and efficient. The study uses a life cycle approach to assess the environmental impacts of building construction, maintenance, and end-of-life treatment, comparing the adopted quincha solution with four hypothetical scenarios using industrial, prefabricated, and/or synthetic construction materials currently adopted in the region. The thermal performance of all the analyzed solutions is also included in order to provide insights into the impact of the operational phase. This paper demonstrates that the quincha solution, in the face of lower thermal insulation compared to the other prefabricated solutions (the U-value of the quincha wall is 0.79 W/m2K while the U-value of the best prefabricated wall is 0.26 W/m2K), has higher thermal inertia (time lag (TL) and decrement factor (DF) are, respectively, 6.97 h and 0.60, while other systems have a TL below 4 h and DF higher than 0.81). For a quantitative environmental evaluation, the carbon footprint (global warming potential), water footprint, and embodied energy indicators are assessed through LCA, which takes into account the mass of the materials and their emission factors. The effectiveness of the quincha solution is also reflected in environmental terms; in fact, it is found to have the lowest carbon footprint (2635.47 kgCO2eq) and embodied energy (42.7 GJ) and the second-lowest water footprint (2303.7 m3). Moreover, carbon sequestration values, which are assessed by estimating the carbon contained in building systems using wood and straw, demonstrate that the quincha tiny house is the only solution that can theoretically reach carbon neutrality (with its carbon storage value at −5670.21 kgCO2eq).

Methodological errors in determining thermal protection of building envelopes in natural conditions

The process of thermal engineering surveys of buildings is considered. This process includes in-kind measurements of heat flux density and temperature on the surfaces of building envelope. Based on the obtained measurement results, the reduced heat-transfer resistance is calculated and compared with the required design values for building. It is shown that when calculating the heat-transfer resistance of the building envelope based on the survey results, methodological errors may occur, which are caused by external natural thermal effects on the building and internal non-stationary heat fl ows in the building envelopes. During in-kind thermal engineering surveys of enclosures of buildings of any type, these methodological errors are a priori unknown, since the measurement conditions differ from the conditions of thermal engineering tests in special climatic chambers, where a stationary difference in air temperature is maintained on the internal and external surfaces of the building envelope. To assess the methodological errors in thermal engineering surveys of buildings in natural conditions that begin on any day of the calendar year and last for several days, physical and mathematical modeling of unsteady heat transfer in the building envelope is performed. The following thermal effects, close to real ones, are taken into account during the modeling: outside air temperature; direct and diffuse solar radiation; radiant heat exchange with the environment. Enclosing structures with low and high thermal protection and thermal inertia are analyzed. Possible values methodological errors of heat engineering surveys are calculated using archived meteorological data for the Moscow region. It is shown that, depending on the season and weather conditions, their values can vary from several units to several tens of percent. The conditions for conducting surveys are determined taking into account different levels of methodological errors. A comparison of two standard methods for calculating heat transfer resistance is carried out and it is shown that the methods give different levels of methodological errors. The results obtained will be useful for specialists conducting heat engineering surveys of buildings and structures using non-destructive testing methods.

Effects of Soil Hygrothermal Properties on the Performance of an Earth-Air Heat Exchanger

Buildings are responsible for a large part of energy demand worldwide. To collaborate to reduce this demand, the use of passive air conditioning has proven to be beneficial for energy savings. In order to improve thermal comfort in built environments, Earth-Air Heat Exchangers (EAHE) can be installed as a low-cost option. Using low energy consumption, in this system, the ambient air circulates through a pipe buried at a certain depth in the ground, causing it to heat up or cool down, depending on weather conditions. These effects are possible due to the high thermal inertia of the soil. In this context, the climatization performance of EAHE depends directly on the hygrothermal properties of the soil, and the effects of heat, moisture, and air transport on the operation of an EAHE are barely explored in the literature due to many difficulties, such as modeling complexity, computer run time, numerical convergence and highly moisture-dependent properties. Therefore, to analyze the effects of hygrothermal properties of soil, a 2D model has been developed to calculate the coupled heat, air, and moisture transfer. The linearized set of discretized governing equations was obtained using the finite-volume method and solved via the MultiTriDiagonal-Matrix Algorithm, substantially improving the numerical stability and reducing the computer run time. To validate the temperature distribution along EAHE, a prototype was built on the Federal University of Technology of Paraná (UTFPR) - Campus Ponta Grossa, which includes 100 mm diameter Polyvinyl Chloride (PVC) ducts, a fan for airflow control, where a series of k-type thermocouples were inserted along the EAHE. Data were recorded hourly using a data acquisition system during the summer period.

Unit commitment in solar‐based integrated energy distribution systems with electrical, thermal and natural gas flexibilities: Application of information gap decision theory

AbstractThe depleting oil reserves, air pollution and increasing energy demand, have overturned the focus of the scientific community to renewable energy sources. Among which the photovoltaic (PV) systems occupy more than half of the market share and are generally installed at the distribution level. The volatile and uncertain nature of these PV productions necessitates flexible resources in energy systems. To this end, the district heating systems have an outstanding flexibility on account of their high thermal inertia. This study investigates the optimal unit commitment scheduling for gas‐fired and non‐gas‐fired distributed generation units (NGU) in an integrated energy distribution system (IEDS) within the physical constraints of the electrical, natural gas and thermal energy distribution networks. Moreover, a planning‐based optimization framework is proposed to investigate the investment of battery storage systems in the electric distribution network under the high penetration of PV systems with the aim of enhancing flexibility and reducing the operating costs of the IEDS. In this framework, the information gap decision theory is deployed under risk‐averse and risk‐seeker strategies to deal with uncertain PV energy production. Additionally, the environmental emissions are considered in a multi‐objective approach. The IEDS is embodied through IEEE 33‐bus EDS, 20‐node natural gas network and an 8‐node district heating systems. Eventually, The proposed approach makes a noteworthy contribution to the advancement of solar energy systems in IEDS.

A Fast-Calibrated Computational Fluid Dynamic Model for Timber–Concrete Composite Ventilated Façades

Timber–concrete composite (TCC) systems join the positive aspects of engineered wood products (good seismftaic behaviour, low thermal conductivity, environmental sustainability, good behaviour under fire if appropriately designed) with those of concrete (high thermal inertia, durability, excellent fire resistance). TCC facades are typically composed of an internal insulated timber-frame wall and an external concrete slab, separated by a ventilated air cavity. However, there is very limited knowledge concerning the performance of TCC facades, especially concerning their thermal behaviour. The present paper deals with the development and optimization of a 2D Computational Fluid Dynamic (CFD) model for the analysis of TCC ventilated façades’ thermal behaviour. The model is calibrated and validated against experimental data collected during the annual monitoring of a real TCC ventilated envelope in the north of Italy. Also, a new solver algorithm is developed to significantly speed up the simulation (i.e., 45 times faster simulation at an error below 3.5 °C compared to a typical CFD solver). The final model can be used for the time-efficient analysis (simulation time of approximately 23 min for a full day in real-time) and the optimization of the thermal performance of TCC ventilated facades, as well as other ventilated facades with external massive cladding. Our simulation strategy partially avoids the expensive and time-consuming construction of mock-ups, or the use of comparably slow (conventional) CFD solvers that are less suitable for optimization studies.

Thermophysical Diversity of Young Lunar Crater Ejecta Revealed with LRO Diviner Observations

Young (<1 Ga) craters on the Moon are known to host diverse mixtures of ejecta with varying spectral and physical properties. In this work, we examine 13 yr of bolometric surface temperature data from the Diviner Lunar Radiometer on board the Lunar Reconnaissance Orbiter over the ejecta blankets of 10 lunar craters of varying sizes (D = 5–43 km) and ages (<10 to ∼200 Ma) to study the spatial variation in their thermophysical characteristics. We find that a one-dimensional thermal model with two free parameters—the bottom-layer bulk density, ρ d , and the transition height between the surface and bottom-layer densities, H—is able to accurately fit these data over our study regions, in contrast to previous models that assumed a constant ρ d . Based on the best-fit model parameters, young crater ejecta can be divided into three classes: (1) “blocky” regions with a high abundance of boulders >1 m in diameter, (2) “clastic” ejecta with varying levels of vertical density stratification, and (3) “impact melts” with high thermal inertia materials buried under a layer of less dense material. These thermophysically derived classes correlate strongly with observed morphology in high-resolution images and polarimetric signatures in decimeter-wavelength radar, and their thermophysical properties evolve distinctly with crater age. This technique represents the first time impact melt in many forms can be quantitatively distinguished by its physical properties from other types of ejecta using remote-sensing data and could have applications in validating models of impact ejecta production and deposition.

Effect of different boundary conditions on the combustion properties and fire characteristics of typical woods

To provide guidance on the bioenergy potential of wood and its fire spread numerical simulation, insights into the combustion properties and fire characteristics of one hardwood (sassafras) and two softwoods (pine and fir) were investigated. The effect of different boundary conditions are focused. The condensed phase decomposition in thermogravimetric analysis indicated that the main degradation processes for all wood combustion could be divided into two stages, and the corresponding demarcation point of conversion rate is 0.4 and 0.35 for hardwood and softwood, respectively. Three specific regions could further be established based on the activation energies variations in Stage Ⅰ. The governing reaction mechanism of sassafras wood is determined to be the diffusion model connect with order-based model, while the reaction mechanism of softwoods (pine and fir) can be considered as the reaction order (1st to three-halves) type followed by diffusion model. The gas phase flaming in FPA combustion experiments suggest that fir and pine wood have a faster charring rate and produce less CO and CO2 during pyrolysis and combustion. Sassafras requires more time to be ignited owing to its high density, which causes higher thermal inertia therefore decelerating the temperature increase on the sample surface. In addition, the dense structure of sassafras leads to an early appearance of the second HRR and MLR peaks. As hardwood has a higher density than softwood, the thermal insulation in hardwood delays char cracking on sassafras wood surface and enhances the duration between ignition and flameout. Such findings should provide guidance for wood combustion modeling and flame spread simulation in future works.

Infrared Thermography Inspection of Stay Cables

The injection of petroleum waxes into bridge stay cables is a proven method for protection against corrosion, primarily due to their sealing properties, adhesion to strands, and thermal stability. However, with a liquefaction point below 70°C, exceptional ambient conditions can lead to partial liquefaction of the injected waxes, especially for cables with a dark sheath, resulting in leaks and extrusions. Sections of stay cables may lose their corrosion protection without visible signs from the outside. This study explores the use of infrared thermography for identifying and mapping areas lacking wax. It involves acquiring high-resolution infrared thermal images of the stay cables and studying temperature variations. Since wax has a higher thermal inertia than air, a thermal gradient is expected between areas with wax and those without after the daily heating cycle. This paper presents a campaign conducted on a cable-stayed bridge in France. During this campaign, temporary instrumentation was deployed to identify the optimal intervention window. Multiple sessions of acquisitions using a high-precision thermal camera were then performed. The acquired images were subsequently rectified and assembled to create uniform and comprehensive panoramas of the stay cables. The results obtained for several characteristic cables are presented and discussed in this paper.

Transient experimental study on cooling performance of a radial turbine with impingement cooling in rotating state

Increasing the inflow temperature of a turbine is an effective approach for enhancing the thermal efficiency of devices operating in the Brayton cycle, such as micro-gas-turbines and waste heat recovery systems. However, elevated temperatures also pose a significant risk of thermal fatigue failure. This paper presents an experimental investigation of impingement cooling for radial turbines, aiming to achieve high cooling performance with a simple structure. High-frequency infrared thermal imaging technology was employed to measure temperature distribution in the turbine rotor under various operational conditions. The results indicate that jet-impingement cooling can substantially reduce the solid temperature of the radial turbine, with a maximum temperature reduction of approximately 44 K achieved by consuming the coolant with ṁre= 5%. Increasing the mass flow rate of the coolant consistently lowers the rotor temperature; however, an increase in rotational speed results in higher thermal inertia, thereby diminishing the cooling enhancement effect. The temperature distribution on the turbine surface exhibits significant periodic characteristics over time, leading to temperature fluctuations of 5 K to 30 K at the hub position. Furthermore, the cooling performance is further enhanced near the jet hole on the back-disc side of the inducer region, while the tip side closer to the exducer obtains better cooling effects.

Defining Sustainable Priorities and Actions for Storage of a Public Archive: A UK Case Study

ABSTRACT Storage facilities often comprise the most energy-intensive burden within archives. One green solution is a passive building with high thermal inertia and airtightness, to create stable environmental conditions without mechanical intervention, and provide appropriate temperature and RH ranges and good air quality for preservation. However, where airtightness is concerned, there is potential for accumulation of pollutants within densely occupied repositories such as library and archive stores. This risk is not addressed by current requirements for greener operation, because operational conflicts arise when balancing these three environmental parameters. This article discusses air quality and its effects on archive materials. It contributes to better understanding of green operation for archives. It presents a preliminary study carried out at Norfolk Record Office in the UK on options to increase archives storage capacity whilst improving both public access and preservation. This concluded that an initial programme to replace low-quality packaging which is a generator of VOCs, and the building of on-site passive storage, were the most sustainable solutions.

The comprehensive research on the transcritical CO2 thermal management system used in thermostatic transport vehicles

Natural fluid CO2 has become the preferred target of refrigerant alternative in the electrified transportation field in recent years to replace positive temperature coefficient (PTC) heaters, reduce energy consumption, and respect the international ban on Hydrofluorocarbons (HFCs) refrigerants. Thermostatic transport vehicles (TTVs) are well suited to exploit the benefits of CO2 due to their working conditions with a broad range of ambient temperatures, extensive transit distances, and substantial heating capacity requirements in cold climates. In this paper, a transcritical CO2 heat pump air-conditioning system used in TTV was constructed initially with proper control logic. Then following the assessment of the system’s steady-state performance, the dynamic operation process under high thermal inertia was thoroughly examined and analyzed in detail. Ultimately, the optimization of the dynamic response process was realized under varying heat flow boundary conditions. The primary results demonstrated that the rationally designed CO2 thermal management system performed admirably in various operating conditions, particularly in the heating mode where the coefficient of performance (COP) exceeded 3.2. Addressing the high-frequency fluctuation caused by the cargo thermal inertia, the temperature could be maintained with only two starts and stops within 3×105 seconds when the system control logic was refined. The optimized thermal management system of TTV efficiently allowed cargo to achieve the proper temperature as quickly as possible and sustain stability. This study provides an effective theoretical basis for the promotion of the transcritical CO2 thermal management system in the field of TTVs.

Analysis of the thermal performances of uninsulated and bio-based insulated compressed earth blocks walls: from the material to the wall scale

The lively international debate on the future of the built environment has placed emphasis on the possibilities offered by bio and geo-based building materials. Among these, raw earth-based materials offer several advantages associated to their reusability and low embodied energy.Nowadays, several companies are basing their production lines on prefabricated raw earth products, as is the case of compressed earth blocks (from now on CEBs). CEBs are commercialized for the construction of massive vertical envelopes, characterized by a high thermal inertia. Nevertheless, in order to compete with conventional building materials, it is also necessary to guarantee a high thermal resistance.In this work, this issue was solved by the design and testing of full-scale uninsulated and bio-based thermal insulated CEB walls. In this way, the thermal performance of CEB walls can be increased to meet the high energy requirements currently adopted in European Countries. Furthermore, the choice of bio-based insulations represents the main novelty of the study, aimed at finding hygrothermal compatible solutions at a low environmental cost.More in detail, this work reports the results of the thermal and physical material characterization of CEBs and of two innovative bio-based thermal insulations (lime hemp and sugarcane bagasse panels), and compare them with measurements made on full-scale uninsulated and insulated CEB walls. For this purpose, the walls are tested inside a double-room climatic chamber where they are subjected to variable temperatures on their two faces, reproducing typical indoor and outdoor conditions during summer and winter conditions in a continental climate.Results show the enhancement of thermal performances of compressed earth blocks walls when thin layers of bio-based thermal insulations are added. The thermal resistance of weakly bio-based insulated CEB walls is found to be nine times (for the sugarcane bagasse insulated CEB wall) and four times (for the lime hemp insulated CEB wall) higher than that of uninsulated CEB walls. Moreover, the addition of the insulation layers enhances the time lag and the decrement factor values of CEBs walls.

Microclimate-Monitoring: Examining the Indoor Environment of Greek Museums and Historical Buildings in the Face of Climate Change

The preservation of cultural artifacts within museums and historical buildings requires control of microclimatic conditions, and the constantly evolving climate certainly poses a challenge to maintaining recommended conditions. Focused on the Archaeological Museum of Delphi and the Church of Acheiropoietos in Greece, our study evaluates the hygrothermal behavior of these buildings with a specific emphasis on the preservation of cultural heritage objects hosted there. An innovative approach to the real-time analysis of data is utilized, aiming to achieve a timely detection of extreme temperature and humidity levels. A one-year monitoring campaign was carried out to achieve a detailed assessment of the indoor climate in selected museums and historical buildings in Greece. The monitoring campaign was performed using dataloggers that were set to measure and record temperature (T) and relative humidity (RH) values hourly. The results allowed for the detection of extreme temperature and relative humidity values, pinpointing the time period that requires more attention. The museum’s heating, ventilation, and air conditioning (HVAC) systems provide temperature control for visitor comfort, but the temperature still rises in summer, highlighting the impact of external climate factors. The church’s lack of HVAC systems widens the temperature range compared to the museum, but significant hourly fluctuations are not observed, underlining the building’s high thermal mass and inertia. Both buildings demonstrate a significant response to changes in outdoor temperature, emphasizing the need for future adaptation to climate change. The HMRhs and PRD indices indicate minimal microclimate risk in both buildings for temperature and RH, reducing the probability of material damage. The church’s slightly higher HMRhs index values, attributed to relative humidity, increases susceptibility due to sensitive materials. Overall, the study highlights the importance of managing microclimatic conditions in historical buildings and proposes careful adaptations for the protection of cultural heritage.

Exploring the integration of bio-based thermal insulations in compressed earth blocks walls

The growing concern about the environmental impact of contemporary construction has posed emphasis on the possibilities offered by bio-based and raw earth construction. The front challenge for the establishment of earth-based technologies in contemporary building markets is the guarantee of high structural and energy performances, while maintaining a low environmental impact. This work focuses on the performance analysis of compressed earth blocks (from now on CEBs) which are currently commercialized for the construction of massive vertical envelopes, with high thermal inertia. However, to obtain an acceptable comfort and an optimized thermal behavior, CEBs walls must also reach a high thermal resistance. This issue can be overcame by the design of insulated CEB stratigraphies using bio-based thermal insulations presenting hygrothermal properties compatible with raw earth-based materials. In this way, the thermal performance of CEBs walls can be increased, while preserving their hygroscopic behavior. In this spirit, this work reports the results of the experimental characterization of three materials: CEB, lime hemp and sugarcane bagasse bio-based insulation panels. It includes their composition, their main physical (dry density, porosity, capillary water absorption), thermal (specific heat capacity, thermal conductivity) and hygrometric (sorption isotherm, water vapor permeability) properties. Finally, these experimental data are used for the implementation of several numerical simulations at a wall scale in a reference climate to estimate the hygrothermal performances of both uninsulated and bio-insulated CEB walls. The simulations allow for a better comprehension of CEBs’ behavior in view of their combination with the chosen bio-based thermal insulations, and give insights into possible moisture-related issues as mold growth or increase of U-value.

Comparing Atmospheric Temperature Fluctuations Across Landed Missions

AbstractWe analyze and compare atmospheric temperature data from three landed missions: Mars Science Laboratory (MSL) Curiosity rover, Phoenix lander, and Pathfinder lander. Pathfinder and Phoenix were lander missions that operated for 84 and 151 sols, respectively. MSL Curiosity is a rover that operates on the surface of Mars. It has recorded air temperature for more than five Mars Years (MY). We denoise and detrend temperature data from each mission and use those results to calculate variance in air temperature as a diagnostic for atmospheric variability at the surface. The results show a consistent seasonal pattern in MSL air temperature variance with little interannual variability outside major dust storms. The global dust storm in MY 34 was accompanied by a decrease in temperature variance and a muted response in peak MY 35 variance the following year. Phoenix (68°N, 2 m measurement height) and Pathfinder (19.7°N, 1.1 m measurement height) air temperatures have larger variance than air temperature from environmental data records at the MSL location (5.4°S, 1.6 m measurement height) at its equatorial latitude. Pathfinder variances per sol are larger than those of Phoenix, possibly due to a combination of Pathfinder's lower albedo surface and lower latitude. This occurs despite the Pathfinder location's higher thermal inertia, which would act to decrease noontime variance relative to a lower thermal inertia surface. Comparison of MSL temperature variance to pressure drops related to convective vortex activity shows consistent seasonal patterns; however, pressure drops tend to increase with increasing rover elevation, while variance remains consistent.

Carrier-phase DNS study of particle size distribution effects on iron particle ignition in a turbulent mixing layer

The ignition and combustion of iron particles in a turbulent mixing layer is studied by means of three-dimensional carrier-phase direct numerical simulations (CP-DNS). A particular focus is set on particle size distribution (PSD) effects on the ignition behaviour by comparing CP-DNS results from using a realistic experimental PSD to DNS data based on a monodisperse (MD) particle cloud with the same equivalence ratio. The CP-DNS solves the Eulerian transport equations of the reacting gas phase and resolves all turbulent scales, while the particle boundary layers are modelled in the Lagrangian point-particle framework. A previously validated sub-model for the oxidation of iron to Wüstite (FeO) that accounts for both diffusion- and kinetically-limited combustion is employed. The mixing layer is initialised with an upper stream of air carrying cold iron particles and an opposed lower stream of hot air. Simulation results show distinct differences in the ignition behaviour between the MD and PSD cases. The ignition of the PSD case is delayed compared to the MD case and does not show any significant particle clustering prior to ignition. Further investigations indicate that the particle size has a crucial effect on the mixing process and ignition time. Small particles start their oxidation process early and already consume some of the available oxygen, while not crucially affecting the gas temperature due to their limited iron mass contribution. Conversely, a slower entrainment into the lower stream combined with higher thermal inertia and the prior oxygen depletion by the small particles leads to a delayed oxidation of the larger particles. As a net result, the PSD case shows a wide spread of individual particle ignition delay times and overall delayed bulk ignition compared to the MD case, where the majority of the particles ignites over a shorter period of time.

Lime-hemp as Wall Insulation - Hygrothermal Performance Analysis by Validated Simulations

The application of lime-hemp as a thermal insulation material is promising: besides its ecological benefits, lime-hemp has a reasonably low thermal conductivity, combined with a good moisture buffering capacity and high thermal inertia. However, adequate design and accurate execution on-site are required, as severe long-lasting moisture accumulation could cause the hemp shives to degrade. In this study, a numerical simulation model is validated using long-term measurements. Then, it is further used to evaluate the hygrothermal performance of lime-hemp as both external and internal wall insulation. The simulations show that high humidity levels are found in lime-hemp as external insulation if an external render with inadequate rain protection is used. If the lime-hemp is used as internal insulation, its high vapour permeability allows the masonry to dry towards the inside, resulting in a drier wall compared to vapour tight materials such as cellular glass.

Energy Efficiency in Historic Museums: The Interplay between Thermal Rehabilitation, Climate Control Strategies and Regional Climates

Museums housed in historical buildings combine the intrinsic value of the collections with the historical and architectural values of the building itself. Although usually made with thick elements with high thermal inertia, very effective in damping and delaying the heat flow, these buildings are usually characterized by elements with low thermal resistance, poor-quality windows and low area/volume ratio in the noblest buildings, which renders them ineffective at maintaining a stable indoor climate adequate for conservation, comfort and energy efficiency issues. In this paper, a simulation study was carried out to analyze the impact of the building location (weather), thermal envelope and climate control strategies by analyzing a generic room of the National Museum of Ancient Art of Lisbon. A simulation study was carried out for 15 European cities to verify the impossibility of standardizing the rehabilitation solutions in cultural heritage since energy needs depend on the location. It was concluded that the focus on climate control strategies has great potential for energy reduction and that in temperate climates of southern Europe, the improvement of thermal transmittance has a reduced effect on the building’s response.

Влияние регенерации слоистого модификатора трения на триботехнические свойства смазочных композиций

The paper examines an influence of the regeneration efficiency of the developed anti-wear additive on tribological properties of the lubricating composition, including a lubricating oil and the additive. The anti-wear additive was a layered friction modifier – molybdenum diselenide MoSe2, mixed in the volume of a composition of unsaturated fatty acids – stearic acid and oleic acid. Lubricating oil M-16G2TSS was chosen as the base lubricant, with respect to which the tribological properties of other lubricants submitted for testing are compared. For all cycles of tests, a volume of no more than 25 cm3 of lubricant was used to avoid high thermal inertia when the test samples moved on the friction machine. Experiments of the regeneration of the additive were carried out on a rotary mixing unit of the author's design, and the solution has a long storage period of 8 640 hours (about 12 calendar months). The possibility of restoring the uniform distribution of molybdenum diselenide throughout the volume of the additive in a suspended state has been revealed. This lubricant composition, after restoration of the structure by stirring, can be used in the production of a lubricant composition based on M-16G2TSS oil. Using a reciprocating friction unit of a friction machine, simulating the cylinder-piston group of a marine diesel engine, the resulting lubricant composition was compared with other lubricants based on molybdenum diselenide, the additive solutions of which have different storage periods before being added to the lubricating oil, as well as with the base lubricating oil. The assessment of the tribological properties of lubricants based on M-16G2TSS oil by determining the weight wear and further using this value to estimate the resource of the friction unit has been made. Rotational regeneration has shown satisfactory effectiveness in partially restoring of the tribological properties of a lubricant composition with the participation of an additive, but is not enough effective compared to rotational pulsation mixing of the additive in order to create perspective lubricant compositions.

Techno-Economic Analysis of the Energy Resilience Performance of Energy-Efficient Buildings in a Cold Climate and Participation in the Flexibility Market

Unexpected power outages and extreme weather encouraged research on energy-resilient buildings throughout the world. Resilient building research mainly focuses on hot weather rather than cold extremes. This study defines resilience terminologies based on the available literature and discusses the impact of energy efficiency on energy resilience performance in energy-efficient buildings due to abrupt power outages in an extremely cold climate. The assessment involves the case simulation of a multistory apartment located in southern Finland at design outdoor conditions (−26 °C) in IDA-ICE 4.8, a dynamic building simulation software, and its techno-economic assessment to ensure building resilience for up to 7 days of power outages. The assessment shows the efficient building envelope can enhance the time taken by the building to drop the indoor temperature to the threshold by approximately 15%. Additionally, the efficient heating system along with the building envelope can reduce the instantaneous power demand by up to 5.3 times, peak power demand by up to 3.5 times, and on average power consumption by 3.9 times. Similarly, the study finds that the total energy requirement during a blackout can be reduced by 4.1 times. The study concludes that enhanced building resilience is associated with energy-efficient parameters such as an efficient energy system and an efficient building envelope that has low thermal losses and high thermal inertia retention. The batteries contribute the maximum proportion to the overall retrofitting cost, and the proportion can go up to 70% in baseline configurations and 77% in efficient configurations of buildings. The analysis concludes that the required investment varies largely with the technologies involved and the combination of components of these energy systems. The assessment finds that the high investment costs associated with batteries and battery recharging costs are the main bottlenecks to feasible flexibility in market participation.