Energy performance enhancement of Trombe walls using 3D geometric ribs

Heating performance enhancement of a new design trombe wall using rectangular thermal fin arrays: An experimental approach

Enhancing the thermal performance of the Trombe Wall is crucial for improving the energy efficiency of passive solar heating systems. This study presents a three-dimensional numerical analysis to investigate the combined effects of internal rib density and geometrical configuration on the thermo-hydrodynamic behavior of a Trombe wall. Using a finite-volume method with laminar flow assumptions based on the Reynolds number, the research is conducted in two sections. First, four rib densities (Nr = 3, 5, 7, and 9) are evaluated using a rectangular rib geometry to identify the best rib number. Subsequently, four innovative designs are compared: rectangular (Model A), semi-circular (Model B), crossed semi-circular (Model C), and spaced semi-circular (Model D) ribs. The findings indicate that while increasing rib count enhances heat transfer through secondary-flow intensification, improvements become marginal beyond Nr = 5 due to excessive flow resistance. At Re = 1600, the Nr = 5 configuration achieves a 68% increase in the average Nusselt number over a smooth channel while maintaining acceptable friction levels. The thermal enhancement factor of case Nr = 5 is the highest in all evaluated Re numbers. Regarding geometry, the model with crossed semi-circular ribs (Model C) provides the maximum thermal enhancement at Re = 1600, with nearly a twofold increase in heat transfer (compared to the smooth channel), albeit at the cost of higher pressure losses. Conversely, the spaced semi-circular ribs case (Model D) achieves the best thermal enhancement factor of 1.51, a 12.7% increase in heat flux, and a lower Poiseuille number. Overall, this study demonstrates that enhanced ribbed configurations can significantly improve Trombe Wall efficiency, with the spaced semi-circular design and five ribs.

Most educational buildings in the north of Italy, whether of dated or recent construction, were designed to comply with the thermal comfort and energy performance requirements set for the heating season due to limited use in the summer months. In the latest years, however, with greater frequency, school buildings have been used to host indoor summer activities, and, due to the warm temperature conditions and heat waves, indoor thermal discomfort is often experienced, with negative impacts on occupants’ task performance. Consequently, the need to guarantee adequate indoor thermal comfort in schools in the warm season is becoming a growing concern for local public authorities. In this context, this work examines a set of strategies for the enhancement of the energy performance and indoor thermal comfort of public school buildings in the cooling season. Thus, two case study public school buildings of dated and recent construction located in Bolzano, Italy, were analyzed and compared. This study shows the potential of passive and semi-passive measures in improving indoor thermal comfort in the spring–summer months and the limit beyond which mechanical cooling and ventilation systems are required to ensure adequate levels of indoor environmental quality and task performance in the warmest months.

Trombe wall is a passive building energy saving technology that uses solar energy to reduce buildings’ heating load and adjust indoor thermal environment. In recent years, much research has been done to increase the thermal efficiency of Trombe wall, but little is focused on the evaluation of Trombe wall from energy, economic and environmental aspects comprehensively. Based on the thermal performance calculation method in ISO 52016-2:2017(E), the authors proposed a concise method to evaluate the energy, economic and environmental performance of ventilated and non-ventilated Trombe walls during a heating season. Firstly, non-iteration calculation methods were introduced for the energy evaluation of Trombe wall and conventional wall during the heating season. Then the economic and environmental evaluation models were brought out according to the energy performance of Trombe wall. After that, a residential building was presented as the case building to evaluate Trombe walls’ performance in five building climate zones of China. The calculation results showed that both heating degree days and solar radiation had significant impact on the energy saving effect of Trombe walls. In comparison with non-ventilated Trombe walls, ventilated ones displayed more obvious energy saving potential in all five climate regions, which can provide averagely 62% more heating for the room in the case study. Though the heating degree days of Guangzhou (hot-summer and warm-winter zone) was the smallest in the five zones, ventilated Trombe wall in the zone had the poorest economic performance due to the scarcest solar radiation during the heating season.

Optimizing energy and environmental performance of passive Trombe wall

Performance analysis of a purified Trombe wall with ventilation blinds based on photo-thermal driven purification

A Trombe wall is a passive solar technology attached to the building envelope to reduce energy demands. In warm climates, due to overheating problems in the cooling season, its efficiency is limited and proper operation is required. In this study, the thermal behavior of a bedroom of a house equipped with a Trombe wall in Yazd with a hot and arid climate under different design configurations and various masonry materials were investigated using the dynamic simulation software DesignBuilder. Monthly ventilation strategies and a schedule of blinds for external glass cover throughout the year were proposed to optimize its energy efficiency. The blinds are applied for shading solar irradiance during summer. They also increase the system's thermal resistance during winter nights. According to the results, a concrete Trombe wall with 2/3 of the façade area is capable of reducing the heating load by 86%. However, its function for summertime is negative, and even in the insulation mode, it can increase the cooling load by 5%. Natural ventilation with the Trombe wall is applicable during moderate seasons; however, its cooling efficiency is limited compared to cross ventilation. The results also highlight that retrofitting a room with a Trombe wall can reduce the annual energy demand by 63%, which is equal to a reduction of 124 kg CO2 emission.

In the realm of composite solid propellant research, the enhancement of energy performance without altering the underlying formulation holds paramount significance. This investigation employed an in situ displacement technique to establish a highly reactive interface, successfully synthesizing the [nCu+nCo+nFe]/μAl composite material, which considerably augmented the energy performance of RDX/AP. The decomposition pathways of ammonium perchlorate (AP) and RDX were optimized, resulting in a reduction in their thermal decomposition temperatures by 1.3 °C and 22.4 °C, respectively. Simultaneously, the highly reactive interface promoted efficient oxygen transport, thereby facilitating more rapid and complete reactions of aluminum. Moreover, the distinct dual-catalyst efficacy of the composite significantly enhanced the combustion efficiency of the composite energy micro-unit. Consequently, the [nCu+nCo+nFe]/μAl+RDX/AP composite energetic micro-units exhibited a notable decrease in combustion duration (from 1.58 s to 1.07 s) and elevated combustion flame temperatures (ranging from 1712.8 °C to 2205.6 °C) alongside an expanded combustion area, thus underscoring its potential for advanced propulsion applications.

Experimental studies on the energy performance of a novel wavy-shape Trombe wall

ABSTRACTThe paper presents further results of an experimental program that was conducted at the Politehnica University Timisoara, studying the behaviour of Composite Steel‐Fibre‐Reinforced‐Concrete shear Walls (CSFRCW) with partially encased profiles. Use of such shear walls represents a widespread solution for providing a lateral load resisting structural system, especially in the case of medium and high‐rise buildings placed in seismic areas. As previous theoretical and experimental studies have proved the performance of such system, the foremost objective of the experimental program consisted in identifying innovative solutions for composite steel‐concrete shear walls with enhanced performance, as steel fibre reinforced concrete which was used in order to replace traditional reinforced concrete. The program consisted in tests on 6 specimens designed as 1:3 scale steel‐concrete composite elements, leading to an experimental matrix that enabled complex comparisons of various solutions. Thus, a steel reinforced concrete shear wall (without any encased profiles) was used as reference, configuration/arrangement of steel profiles and ratios of steel fibre reinforcement were varied within the other five specimens. The effective stiffness, strength and ductility is evaluated using the experimental results.

Fire performance enhancement of cold-formed steel walls: experimental and numerical study

The integration of new building materials incorporating phase change material (PCM) into the building envelope leads to an increase of the heat storage capacity, which may have an influence on minimizing the cooling demand and heating of the building. This work addresses a thermal performance enhancement of brick walls with incorporated PCM. The improvement has been assessed through a numerical approach in dealing with a 1-D transient conduction problem with phase change, while leaning on experimental results from a transient guarded hot plates method. The simulations have been fulfilled using a hybrid method combining both the finite volume method and an enthalpy porosity technique. The results of this combined approach are in good agreement. In the light of the findings obtained, it appears that PCM incorporation into a brick masonry can both reduce peak temperatures up to 3?C and smooth out daily fluctuations. Thereby, the evaluation achieved can turns out useful in developing brick walls with an incorporated PCM for passive cooling, thus improving buildings thermal performance.

In-plane performance of un-reinforced brick masonry (URBM), retrofitted with nominal Reinforced Concrete (RC) bands, was investigated under diagonal compression tests using full-scale and half-scale specimens. The retrofitting technique is cost-effective, reliable, simple, easily implementable, and minimally intrusive. Six URBM wall specimens (three full-scale and three half-scale) served as control specimens, and similarly, six (three full-scale and three half-scale) were retrofitted with RC bands. All specimens were tested under diagonal compression in a computer-controlled servo-hydraulic universal testing machine using displacement-controlled scheme. Data on applied force and corresponding wall displacements were recorded. Responses of retrofitted specimens were compared with control specimens in terms of strength, deformation capacity, and failure patterns. Retrofitted specimens exhibited progressive damage due to ductile failure, showing a significantly increased deformation capacity and providing sufficient warning time before collapse. However, control specimens showed sudden catastrophic collapse due to sliding of bed-joints. Overall, retrofitted specimens demonstrated a significant enhancement of ductility. Next, a semi-empirical prediction formula for diagonal load capacity was established through macro-modelling approach and subsequent regression analysis to capture experimental results. From results, the proposed retrofitting scheme provides a promising solution for seismic risk reduction of existing deficient masonry structures in rural areas of the Indian subcontinent and elsewhere.

Role of UHPC in-lieu of ordinary cement-sand plaster on the performance enhancement of masonry wall under close-range blast loading: a finite element investigation

The use of mesh reinforcement with mortar on existing brick infill walls of reinforced concrete (RC) frames is a recommended seismic strengthening procedure in the Turkish Seismic Code (2007). The premise of the method lies in its ease of application and success in eliminating the out-of-plane failure of existing infill walls. The performance of the mesh reinforced mortar (MRM) application was investigated by pseudo-dynamic (PsD) and cyclic testing. A three-story-three-bay 1:2 scale RC frame with hollow clay tile (HCT) infills in the middle bay was first tested using a continuous pseudo-dynamic test method for three synthetic ground motions compatible with the Duzce city center response spectrum. The test specimen was code complaint. No significant structural damage besides some cracking in the boundary columns was observed but the infill walls almost collapsed. After removing the infill walls of the central bay, a new HCT wall strengthened with MRM was built and the rehabilitated frame was retested under a second series of PsD and reversed cyclic loading schemes. This Chapter reports the findings of the experimental study by placing special emphasis on the seismic response of the code compliant test frame.