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Passive safety systems are integrated into the latest generation of Light Water Reactors (LWRs), including small modular reactors. This paper employs the US-NRC TRACE thermal hydraulic code to examine the performance of a passive safety condenser known as SACO, designed to serve as the ultimate heat sink for dissipating decay heat during accident scenarios. The TRACE model is constructed with reference to the PKL/SACO test facility. The safety condenser (SACO) is interconnected with the PKL facility via the secondary side of steam generator 1, effectively serving as a third natural circulation cooling loop during accident scenarios. In the present research, the thermal-hydraulic behavior of the PKL facility is investigated in the presence of the SACO passive safety system during an extended SBO with Loss of AC Power accident scenario. This SBO can be categorized into three distinct phases depending on the activation of the SACO system and the refilling process of the SACO pool. The first phase is depressurizing using primary and secondary relief valves, the second phase is cooling down using SACO system, and the third phase is the refilling of SACO pool. The findings indicate that the SACO system effectively manages to dissipate all decay heat, even though there is temporary evaporation of the SACO water pool. Furthermore, this study provides sensitivity analysis for the assessments of system codes on the selection of maximum time step.

Today's industrial processes use a variety of smart structure systems technologies. Various construction devices can significantly enhance a structure's ability to adapt to environmental changes. Smart structures are essential to the development of building technology. These forms of technologies are developing intelligent structural systems that behave like living systems and can perceive their environment. The objective of the research is to examine the connection of these professional systems, which become increasingly dependent over time. The research acknowledges and give emphasis to the significant role played by different types of systems (passive, semi-active, active, and hybrid) in formative the scope of construction through the analysis of novel techniques and innovative approaches. The paper state the assorted classification of smart structure schemes that have a significant role to serve the cycle life of the structure by reducing severe subjected damage to it. The study aims to investigate how these schemes of callings are inseparably connected, creating ever more advantageously as time goes on. The think about state and recognize the significant part of different categories of schemes (inactive, semi-active, active, and hybrid schemes) within the development scope through examination, unused methods and inventive strategies. The paper displayed the different categories of shrewd structure schemes that have a critical part to serve the cycle life of the structure by diminishing serious subjected harm to it.t. Furthermore, the research also demonstrated the smart structure's useful behavior, which is taken into account at every stage of the civil engineering design process.

Voltage and current requirements imposed by direct current loads are highly demanding in modern applications such as microgrids and electric vehicles. High-performance converters and controllers are required for these applications. The versatile buck-boost (VBB) converter has shown comparative advantages such as non-inverting output, wide bandwidth, and smooth transition between operation modes and current control loops. The control law can enhance these intrinsic advantages. In this work, a passivity-based current controller is designed and implemented for this converter. The control is based on the system’s dissipative characteristic to match the desired operating point’s power function. The proposed controller maintains the simplicity and robustness of a PI control while guaranteeing high performance and dynamic stability. This control does not depend on the converter’s component values. Theoretical analyses are complemented with numerical simulations and experimental results on a purpose-built prototype. The proposed control shows stable and high performance in both buck and boost modes, demonstrating its effectiveness and reliability in real-world conditions, presenting for the buck and boost modes equal settling times in transitions (about to $100~\mu $ s). These benefits make it particularly suitable for demanding applications requiring robust and efficient power conversion.

The Artificial Electric Field Algorithm (AEFA) is a recently developed optimization algorithm inspired by the principles of electrostatic force and the law of motion. It operates as a stochastic population-based algorithm and utilizes probabilistic techniques to search for solutions. Due to its stochastic nature, it is crucial to investigate the numerical stability of AEFA. Such a study helps in determining optimal parameter values for the AEFA scheme. In this article, we analyse the stability of AEFA using two different criteria: Von Neumann stability and agent dynamics. Both methods provide sufficient conditions for the stability of AEFA, enabling the adaptation of its parameters. We further examine the trajectory behaviour of agents by evaluating various benchmark functions from the CEC 2021 test suite. Through illustrative examples, we demonstrate the theoretical and experimental studies, highlighting the stable nature of AEFA and validating the proposed stability conditions. [ABSTRACT FROM AUTHOR]

This work details the performance and behaviour of the suspension system by varying the suspension-damping coefficient for different vehicle speed over a sinusoidal bump. For this analysis 2-DoF quarter car suspension model is used. Governing equations of motion of the system are developed using Newton's law. Suspension system functions like sprung mass acceleration, suspension deflection, and tire deflection are developed using a transfer function model. Bode plot of the various transfer functions is simulated using Matlab/Simulink tool. [ABSTRACT FROM AUTHOR]

There is an increasing interest in passive safety systems to minimize the need for operator intervention or external power sources in nuclear power plants. Because a passive system has a weak driving force, there is greater uncertainty in the performance compared with an active system. In previous studies, several methods have been suggested to evaluate passive system reliability, and many of them estimated the failure probability using thermal–hydraulic analyses and the Monte Carlo method. However, if the functional failure of a passive system is rare, it is difficult to estimate the failure probability using conventional methods owing to their high computational time. In this paper, a procedure for the application of the Chernoff bound to the evaluation of passive system reliability is proposed. A feasibility study of the procedure was conducted on a passive decay heat removal system of a micro modular reactor in its conceptual design phase, and it was demonstrated that the passive system reliability can be evaluated without performing a large number of thermal–hydraulic analyses or Monte Carlo simulations when the system has a small failure probability. Accordingly, the advantages and constraints of applying the Chernoff bound for passive system reliability evaluation are discussed in this paper.

This paper concerns a hybrid vibration reduction system (HVRS) equipped with a linear electrodynamic motor (LM). The objective of the study was to implement the HVRS in a scaled vehicle suspension and reveal the benefits of its application in the system. First, a mathematical model of a quarter-vehicle suspension with the HVRS was formulated. Next, the dynamic similarity method was employed to conduct numerical simulations of the passive vibration reduction system (PVRS). Subsequently, an algorithm for HVRS controlling was developed. Then, the system was investigated experimentally under deterministic and random excitations. The results confirmed the effectiveness and applicability of the proposed HVRS. [ABSTRACT FROM AUTHOR]

The aim of the study is to develop a system for converting, accumulating, and delivering solar energy that is based on the development of an innovative solar panel with heat pipes and a heat storage wall, for the construction of passive structures. The novel aspect of this experiment is the utilization of concrete walls that have different recyclable materials added to their structure in various proportions. The solar energy from the sunny façades is transformed by this system into thermal energy, which is then transferred by integrated heat pipes in a massive element with high thermal inertia. Using insulated shutters, thermal energy can be stored during the day and released at night to keep the room at a comfortable temperature. In order to integrate the modules into the solar recovery system, four concrete samples were cast with a blend of standard and waste aggregates. Four heat fluxes of 100 W/m2, 150 W/m2, 200 W/m2, and 250 W/m2 were applied to each global system. Thermal imaging data and numerical simulations both supported the findings of temperature sensors. The most effective mixture, fly ash and chopped PET, delivered temperatures that were, on average, 3.3% higher at the end of the charging cycle than those measured for the control sample. The discharging cycle of the concrete block with fly ash and sawdust was the most effective, with an average temperature loss of 5.0 °C as compared to 5.5 °C for the control sample, on average. [ABSTRACT FROM AUTHOR]

This research aims to present a state-of-the-art cleaning technology solution that effectively overcomes the dust accumulation issue for conventional photovoltaic systems. Although continuous innovations and advanced developments within renewable energy technologies have shown steady improvements over the past years, the dust accumulation issue remains one of the main factors hindering their efficiency and degradation rate. By harvesting abundant solar thermal energy, the presented self-cleaning system uses a unique thermomechanical property of Shape Memory Alloys to operate a solar-based thermomechanical actuator. Therefore, this study carries out different numerical and experimental validation tests to highlight the promising practicability of the developed self-cleaning system from thermal and mechanical perspectives. The results showed that the system has a life expectancy of over 20 years, which is closely equivalent to the life expectancy of conventional photovoltaic modules while operating under actual weather conditions in Dammam city. Additionally, the thermal to mechanical energy conversion efficiency reached 19.15% while providing average cleaning effectiveness of about 95%. The presented outcomes of this study add to the body of knowledge an innovative methodology for a unique solar-based self-cleaning system aimed toward smart and modern photovoltaic applications. [ABSTRACT FROM AUTHOR]

• The TRACE 5.0 code was validated against the ATLAS C2.2 experimental data. • The validation includes the pre-test and the post-test calculation. • The ATLAS C2.2 test conducts a 13% IBLOCA in Cold Leg, with the Passive Emergency Core Cooling System. • The key thermal–hydraulic parameters were evaluated by TRACE simulation. TRACE 5.0 code was validated for simulating a 13% IBLOCA in Cold Leg 1A, with an emphasis on evaluating the Passive Emergency Core Cooling System, utilizing the ATLAS facility. Methodologically, after detailed comparisons of transient thermal hydraulic parameters with experimental data, TRACE model and condition were adjusted to reduce the discrepancy between simulation and experiment. ADV depressurization, Safety Injection Tank (SIT) flow rates, and break flow were main contributors impacting safety system activations and core water levels. The sensitivity studies in the simulation led to improved alignment with experimental results, providing enhanced insights into reactor behaviour during IBLOCA. The criticality of precise modelling techniques in accurately simulating nuclear reactor safety systems was undersored and a user dependence of TRACE code during the the validation process was also discussed. [ABSTRACT FROM AUTHOR]

This article is largely concerned with the time-discretization of differential-algebraic equations (DAEs) with complementarity constraints, which we name differential-algebraic linear complementarity systems (DALCSs). Specifically, the Euler implicit discretization of DALCSs is analyzed: the one-step nonsmooth problem, which is a generalized equation, is shown to be well-posed under some conditions; then the convergence of the discretized solutions is studied, and the existence of solutions to the continuous-time system is shown as a consequence. Passivity of some operators is pivotal to the analysis. Examples from circuits, mechanics, and switching DAEs illustrate the applicability of the developments. [ABSTRACT FROM AUTHOR]

BACKGROUND Environmental conditions affect the quality of the fruits and their organoleptic properties. In low‐tech greenhouses, these environmental conditions are frequently not optimal for crops. Therefore, the present study demonstrates the effects of the use of an integrated passive heating and cooling system in a greenhouse located in the Mediterranean area on the quality of pepper fruits. RESULTS: The results indicate that the passive system utilized (i) improved many parameters, such as average weight of fruits, °Brix, glucose and fructose content, and P and K content; (ii) increased the values of b* and hab*; and (iii) reduced total phenolic compounds, total amino acids content, and Fe and Zn content. However, the degree of the effect of the climatic factors on these parameters was also affected by harvest time. CONCLUSION: This novel study highlights the possibility of improving the nutritional quality of pepper fruits by modifying the environmental conditions through the use of passive heating and cooling systems at the same time as reducing the carbon footprint. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The latest earthquakes history shows that resistant conception, safe and economical structures are a daily challenge for structural engineers. Among the newest vibration control devices figures the inerter which is a device which can develop a large fictive mass (it consists of a mass amplification effect) using rotational inertia. In this research work, the effectiveness of a traditional passive tuned mass damper (TMD) is compared with a tuned mass damper inerter (TMDI) which consists generally of tuned mass damper coupled with an Inerter. Both devices are used to control a base-isolated structure vibration submitted to several seismic records. In This study, a base-isolated structure of six stories (6 DOF) was equipped with (TMD) and (TMDI) and a time history analysis were performed under different earthquake records (El Centro, Kobe, Kocaeli). The mathematical model of the building is established in MATLAB Simulink. The simulation results illustrated he robustness, performance and effectiveness of the structure equipped with a (TMDI). The dynamical parameters of interest were base and top displacement as well as the base shear force and peak inerter force produced.

The present study aimed to develop a computational model to understand the effect of air gap depth on the Trombe wall (TW) system. The simulation was performed for midday of January 17, 2017, at a Kirkuk city/Iraq; at this time, the solar intensity was at a maximum value equal to 487.1 W/m2, ambient temperature 10.1°C and wind speed 0.7 km/h. The result of the simulations is investigated with the experimental work in the literature. The various parameters such as thermal efficiency, inlet and outlet temperatures from air gap, room temperature and air mass flow rate in the air gap channel have been considered in simulation. The comparison result showed a good agreement between the predicted results and experimental work. This research work will be useful for the research community to understand the effect of air gap depth in TW system. [ABSTRACT FROM AUTHOR]

Conventional passive solar systems can significantly reduce a building's heating load. However, the integration of passive heating and cooling systems in the same building and the benefits of actively controlling passive systems has largely been unexplored. The objective of this study was to determine the relative performance of a passive solar heating and sky cooling system operating with a range of control strategies, with the goal of minimising the overall annual energy use for space conditioning. A combined system (CS) and a separate system (SS) were simulated with thermal networks using MATLAB, with weather data for Louisville, KY. The control strategies simulated included: Seasonal, Ambient, Room and Matrix. The highest fraction of energy supplied by ambient sources for the SS was 0.707 with Matrix control, while for the CS, the highest fraction (0.704) was with Matrix temperature control with switchable attributes for heating and cooling.

This study evaluates the performance of a heat-pipe-augmented sky radiator system modelled using MATLAB. It was developed to simulate thermal networks with the following nodes: polyethylene cover(s), radiator plate with selective surface, heat pipe condenser end, heat pipe evaporator end, thermal storage fluid, fluid container wall, and room. Applying a windscreen of polyethylene that is mostly transparent to long-wave radiation, a drawback is its susceptibility to optical property degradation. Sky fractions of 100% were possible in cities with small cooling loads (Rock Springs, Seattle, San Diego and Denver). Sky fractions of over 50% were achieved in New Orleans and Houston and over 40% in Miami. A second study examined the degradation of polyethylene cover material. Louisville and two challenging climates (Miami and New Orleans) were simulated. In the Louisville, Miami and New Orleans climate, performance was reduced by 2.7, 14.1 and 9.0%, respectively, due to degradation of the cover’s material.

Among all the non-conventional energy sources, solar energy is one of the most promising and renewable alternativesource. Solar water heater can be one of the medium to make best use of this renewable energy for human betterment. Thecurrent work is targeted to examine the performance of solar water heater with different absorber plates viz flat plate, VTrough and compound parabolic concentrator. The developed system is intended to supply hot water for a family at a lowcost. This is regional study and illustrates how selecting a proper concentrator can increase the thermal efficiency of thissolar based system. It was experimentally found that, the solar water heater with compound parabolic concentrator profileas absorber outshines over other two models giving 20.58% more efficient results than V Trough whereas V Trough givesus 20.37% more efficient results than Flat plate. Also, it is found that, less mass flow rate is required for obtaining higherdegree of temperature in case of solar water heater with compound parabolic concentrator.

This paper presents the results of an analysis of a universal cooling system for the core of re- search reactors built on the passive principle of natural convection. A 3-D model, technologi- cal and design diagrams of the reactor installation are provided, along with examples of nu- merical evaluation of transients during the operation of the cooling circuit in normal and emergency modes to substantiate the possibility of using such a cooling system in research re- actors of small and medium power. The principal feature of the described passive system is the absence of not only active elements, such as circulation pumps and shut-off and control valves from the cooling circuit, but also of passive elements with moving parts, such as a check valve. The cooling circuit includes only vessels, piping and a heat exchanger. The absence of elements with mechanical moving parts can significantly reduce the likelihood of equipment failures and improve the reliability of such a cooling system while also reducing its cost. The versatility of the proposed system allows it to be used for a wide range of research reactor plants with various capacities, which are nowadays being developed designed to carry out programs in various areas of research and applied usages related to nuclear technologies.

Among all the non-conventional energy sources, solar energy is one of the most promising and renewable alternative source. Solar water heater can be one of the medium to make best use of this renewable energy for human betterment. The current work is targeted to examine the performance of solar water heater with different absorber plates viz flat plate, VTrough and compound parabolic concentrator. The developed system is intended to supply hot water for a family at a low cost. This is regional study and illustrates how selecting a proper concentrator can increase the thermal efficiency of this solar based system. It was experimentally found that, the solar water heater with compound parabolic concentrator profile as absorber outshines over other two models giving 20.58% more efficient results than V Trough whereas V Trough gives us 20.37% more efficient results than Flat plate. Also, it is found that, less mass flow rate is required for obtaining higher degree of temperature in case of solar water heater with compound parabolic concentrator. [ABSTRACT FROM AUTHOR]

The incorporation of phase change materials (PCMs) in buildings increases their thermal mass and hence improves thermal comfort through internal temperature stabilization. In this paper, the thermal performance of an active PCM system was compared with that of a passive system. Two identical test huts, each equipped with a control system were used to investigate the potential of passive and active systems for energy-saving and peak load shifting. One of the huts was equipped with PCM-impregnated wallboards, while the other hut was provided with active air-PCM heat storage units designed and fabricated at the University of Auckland. Both huts were cooled with an air conditioner or heated using both solar and electric heaters. For space cooling, the hut with active PCM consumed 8% more electricity to maintain comfort, although the energy storage capacity of PCM used was 50% less than that used in the active application. Over ten days in winter, the energy consumed in the hut provided with an active storage system was 22% less when both passive and active systems had the same amount of energy storage capacity. The investigation of peak load shifting showed 32% less in electricity cost when an active storage system was used. Image 1 • The performance of an active PCM system was compared with that of a passive system. • Active system showed a greater energy-saving and a more efficient peak load shifting. • 32% less electricity cost was achieved when an active storage system was used. • Active systems provide better level of control, and less adverse environmental impact. [ABSTRACT FROM AUTHOR]

Pontryagin space operator valued generalized Schur functions and generalized Nevanlinna functions are investigated by using discrete-time systems, or operator colligations, and state space realizations. It is shown that generalized Schur functions have strong radial limit values almost everywhere on the unit circle. These limit values are contractive with respect to the indefinite inner product, which allows one to generalize the notion of an inner function to Pontryagin space operator valued setting. Transfer functions of self-adjoint systems such that their state spaces are Pontryagin spaces, are generalized Nevanlinna functions, and symmetric generalized Schur functions can be realized as transfer functions of self-adjoint systems with Kreĭn spaces as state spaces. A criterion when a symmetric generalized Schur function is also a generalized Nevanlinna function is given. The criterion involves the negative index of the weak similarity mapping between an optimal minimal realization and its dual. In the special case corresponding to the generalization of an inner function, a concrete model for the weak similarity mapping can be obtained by using the canonical realizations. [ABSTRACT FROM AUTHOR]

We study certain transformations of Nevanlinna families and Schur class operator-valued functions, construct their realizations by means of compressed resolvents and by the transfer functions of conservative systems, and find fixed points of such transformations. In particular, we characterize some automorphic Schur functions and corresponding them Nevanlinna families, including periodic and scale invariant. [ABSTRACT FROM AUTHOR]

• A wall system composed by a CO 2 -filled transparent insulation and PCM is evaluated. • A detailed mathematical model for thermal performance evaluation has been developed. • The proposed model has been validated with outputs from complex simulation tools. • The wall system has been modelled considering a Mexico City office as case study. • CO 2 as a gas filling insulation option presents the best technoeconomic potential. Novel thermal insulation materials and wall configurations have the potential to play a major role in reducing energy demand and carbon emissions from the building sector. In this study, a passive heating wall system composed by a CO 2 -filled transparent thermal insulation (TTI) and an organic phase change material (PCM), and a passive cooling system composed by a Tromble Wall with nano-film and a CO 2 -filled TTI are proposed and evaluated. The aim is to present a detailed analytical model for rapidly calculating thermal performance of the proposed wall configurations. As case study, a 108 m2 south façade of a building located in Mexico has been used. Outputs suggest that as a passive heating measure, the system has the potential to supply heat in the order of 118 W, 126 W, 134 W, and 157 W, during the months of December, January, February, and March respectively. Additionally, thermal performance and air velocity simulations suggest that for the heating case, considering an outdoor and indoor temperature conditions of 0 °C and 21 °C respectively, the internal layer surface reaches a temperature of 9.2 °C; while for the cooling case, considering outdoor and indoor temperature conditions of 25 °C and 21 °C respectively, it reaches 22.5 °C with a maximum indoor air velocity of 0.5 m/s. Compared to other gases, CO 2 could hold a greater potential due to its low thermal conductivity and capital costs. Large-scale implementation of such systems could make the building sector an interesting option as an artificial sink for carbon storage. [ABSTRACT FROM AUTHOR]

Passive discrete-time systems in Pontryagin space setting are investigated. In this case the transfer functions of passive systems, or characteristic functions of contractive operator colligations, are generalized Schur functions. The existence of optimal and ∗ -optimal minimal realizations for generalized Schur functions are proved. By using those realizations, a new definition, which covers the case of generalized Schur functions, is given for defects functions. A criterion due to D.Z. Arov and M.A. Nudelman, when all minimal passive realizations of the same Schur function are unitarily similar, is generalized to the class of generalized Schur functions. The approach used here is new; it relies completely on the theory of passive systems. [ABSTRACT FROM AUTHOR]

• The ELSMOR facility has been built to test a passive heat removal system. • ELSMOR test 00099_C has been selected to perform a code benchmark. • AC2, APROS, CATHARE, RELAP and TRACE codes have been adopted. The EU-funded ELSMOR (Towards European Licencing of Small Modular Reactors) project seeks to design methods and tools for stakeholders to assess and verify Light Water SMRs' safety when installed across Europe. Within the project, an experimental facility has been built at SIET (Piacenza, Italy) to test a passive heat removal system. The passive system is based on natural circulation, with a plate-type Compact Steam Generator (CSG) as heat source and an in-pool condenser as heat sink. An experimental campaign has been conducted to investigate the effect of different parameters on the passive system behavior (e.g. secondary side filling ratio, primary system temperature, pool level, presence of non-condensable gases, etc.). Among the various tests, ELSMOR test 00099_C has been selected to perform a code benchmark and ten parameters were selected for the code comparison. The chosen test explores the effect of the secondary side filling ratio from 60.16% to 24.96%. In the benchmark, the codes from the European reference chains have been applied, Apros by VTT, AC2 by GRS and CATHARE by CEA, and they have been compared with the results obtained with RELAP5 by ENEA and TRACE by PSI. In general, all the codes were able to predict the experimental data both from a qualitative and quantitative point of view. The main discrepancies have been observed in some results for the prediction of the secondary side pressure, secondary side CSG inlet temperature and secondary side flow rate. [ABSTRACT FROM AUTHOR]

Passive cooling mechanism for a nuclear reactor has been proven to be very important since the Fukushima Daiichi Reactor accident that was caused by active cooling system malfunction due to total loss of electrical power source. In the Center for Nuclear Reactor Technology and Safety of BATAN, the cooling mechanism was studied by using a natural circulation test loop named FASSIP-01 that applied thermosyphon mechanism of water inside pipes of 1” diameter. This study aimed to analytically predictthe thermal characteristics of the loop including its response time towards steady condition usingthe MATLAB calculation program. This prediction derived the influence of several parameters such as the heat transfer coefficient of the cooler side (h-cooler), the heater power, the elevation difference between the heater and cooler(DZ), and the effects of the insulation thickness of pipe (IT) on the flowrate, temperature, and the heat power distribution across all components in the loop. The result showed that byavoiding boiling condition, for transferring the heater power of 1000 W and 2000 W,the needed h-cooler exceeds 200 and 400 W m-2°C-1, respectively. For a h-cooler of 200 W m-2°C-1, the circulation flow rate increased from 0.04 to 0.06 kg/s-1 for heater power increase from 1000 W to 2000 W. Those flow rates were decreased to 0.037 and 0.052 kgs-1 by increasing h-cooler to 1000 W m-2°C-1.The results were in agreement with other studies on rectangular loops in the literature.The time needed to reach 95 % towards steady state was predicted to be more than 13 hours. Reduction of this time to less than five hours was possible by reducing the heater tank volume from 100 L to 30 L or by modifying the starting heater input power.

In this article all the effective parameters in response of nonlinear passive viscous systems are investigated. Here, the term response is referred to the maximum inter-story drift and maximum absolute acceleration of the stories. Inter-story drift is known as the structural failure index and maximum absolute acceleration is known as the nonstructural and acceleration sensitive equipment in buildings. Based on the results, the more effective parameters in these systems are initial stiffness and strength of the building, amount of supplemental damping used in the system, stiffness of the braces connecting the dampers to the building and number of the stories. In order to show the effect of each pre-mentioned parameters, many linear and nonlinear passive control systems were analyzed by the time history method. For decreasing the influence of dominant input frequency of the excitation record and also for generalization, two white noise time histories normalized to the 1g were used as the input excitation. The results show that reduction of stiffness and strength are the key parameters in reducing absolute acceleration and also increasing the brace stiffness and supplemental damping are the most effective parameters in reduction of inter-story drift. In other words, if in design of passive control systems, only increasing the damping of the system is considered, the absolute acceleration of the system may be increased and as the result the acceleration sensitive equipment will experience the most failure during the earthquake.

Green façades are passive living technologies applied to buildings. They produce many advantages for human wellbeing, building performance, and city environments. Knowledge of the energy behaviour of green façade systems is needed to inform their best design and application, and to define their energy performances. Heat and mass exchanges between the system and the surrounding environment must be determined. In this paper, the schematisation of the green façade system into layers and the energy balance approach are proposed. This study focuses on the analysis of the convective heat transfer occurring between the plant layer and the external air. It is difficult to realistically describe this mechanism and many approaches in the literature were considered. Six different formulae were evaluated. Mathematical modelling and empirical data were both used. Once it was discovered that forced convection was the prevailing convective type, selected formulae were applied to the data, which were collected from an experimental green façade at the University of Bari. Based on the energy balance of the plant layer, a comparison between the calculated and measured values was carried out. Qualitative and quantitative statistical methods were used to assess the goodness-of-fit of the considered convective models. These analyses suggest the least and the most suitable approaches for convective heat transfer evaluation. The empirical equation of Morrison and Barfield and an adaptation to green façades of Deardorff model showed the best agreement. This study could be extended in order to write codes for building energy simulation software. Image 1 • Energy balance knowledge of green façades is fundamental in building design. • Forced convection is the prevailing convection regime. • Mathematical models and empirical data are used to calculate convective fluxes. • The best-fitting formulae for the convective flux are found. [ABSTRACT FROM AUTHOR]

Conventional passive solar systems can significantly reduce a building's heating load. However, the integration of passive heating and cooling systems in the same building and the benefits of actively controlling passive systems has largely been unexplored. The objective of this study was to determine the relative performance of a passive solar heating and sky cooling system operating with a range of control strategies, with the goal of minimising the overall annual energy use for space conditioning. A combined system (CS) and a separate system (SS) were simulated with thermal networks using MATLAB, with weather data for Louisville, KY. The control strategies simulated included: Seasonal, Ambient, Room and Matrix. The highest fraction of energy supplied by ambient sources for the SS was 0.707 with Matrix control, while for the CS, the highest fraction (0.704) was with Matrix temperature control with switchable attributes for heating and cooling. [ABSTRACT FROM AUTHOR]

One of the most critical innovations in the solar energy conversion is the use of concentrators for generating power from a smaller area of the cell. The thermal management has an exceptional role in the concentrated photovoltaic (CPV) cell, without which the operating temperature will increase owing to the thermal degradation. In the present study, a prototype of low CPV with single‐cell configuration using a Fresnel lens and a manual tracker with geometrical concentration ratio of up to 25 Suns is made. The performance of the CPV with passive cooling arrangements, such as heat sink and loop heat pipes (LHPs), is analyzed under real‐time outdoor conditions. The results obtained infer that the LHP‐based cooling system has brought down the average temperature rise above ambient to 37.8°C from 54.16°C and 72.6°C in the heat sink and bare CPV systems, respectively. Also, the LHP managed to reject the heat to the surrounding with an average thermal resistance of 1.005°C/W, which is the least when compared with the heat sink. Apart from the instabilities caused by the interference of clouds, the CPV with the LHP cooling system could generate 10% more power output than the one with a heat sink. [ABSTRACT FROM AUTHOR]