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1

Utilisation of bio-based acorn cupule aggregates in producing lightweight concrete: Influence of thermal treatment on performance characteristics

Hamraoui Somia, Boukhelkhal Djamila, Guendouz Mohamed

Budownictwo i Architektura

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2026

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Vol. 25, no. 2

art. no 26031

EN

Environmental and climatic challenges necessitate careful consideration and strategic planning regarding the materials and techniques employed across all sectors. To reduce the depletion of non-renewable resources and to improve and achieve sustainable development, researchers have recently become interested in the trend of using bio-based materials as alternative resources in numerous fields. Given that the construction sector poses the main threat to environmental balance due to its high consumption of raw materials, such as fine and coarse aggregates widely used to create different concrete, and energy resources, particularly for building ventilation and cooling, this study aims to use acorn cupule (AC) waste as a low-cost and renewable lightweight bio-aggregate to develop green lightweight flowable sand concrete (FSC) with high insulation properties. Since such organic materials have a negative impact on concrete's mechanical performance, a heat treatment was applied to this AC aggregate to enhance its surface properties. For this purpose, the natural sand was volumetrically substituted with raw and heat-treated acorn cupule aggregates (RAC and HAC) at 10, 20, 30, 40, and 50% in FSC. The results showed that incorporating RAC aggregates decreased the concrete’s workability compared to the control one. The density, compressive strength, and flexural strength were reduced by up to 50%, 84%, and 68%, respectively, while the thermal conductivity was improved by approximately 24–89%. The heat treatment of RAC aggregates enhanced FSC flowability; reduced water absorption, reducing concrete porosity by 25%; and significantly improved the compressive and flexural strength by up to 41% and 45%, respectively. However, a slight decline in thermal performance was recorded. Finally, with up to 30% RAC and 40% HAC, AC was proven to be a highly recommended ecological alternative to natural aggregates in the concrete industry for developing lightweight-insulating-structural FSC.

2

A descriptive view of rammed earth performance: bibliometric analysis and systematic literature review

Bilad Ayoub, Ikharrazne Lmokhtar

Budownictwo i Architektura

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2026

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Vol. 25, no. 2

art. no 26032

EN

Rammed earth is a sustainable material with several features that warrant being studied and analysed for safe use as a green building for low-rise buildings due to its minimal CO₂ emissions. The initial section of this paper used bibliometric analysis to review various studies conducted on rammed earth from 2010 to 2024, comprising 960 publications. The subsequent section presents a systematic literature review of 52 publications, focusing on the mechanical properties of rammed earth, such as compressive strength, tensile strength, shear strength, and shear parameters (friction angle and cohesion), as well as thermal performance. The analysis of the outcomes of the previous studies showed that the compressive strength of unstabilised rammed earth ranges from 1 to 2.75 MPa, while stabilised rammed earth exhibits a range of 1.2 to 9.40 MPa, which is adequate for single-story and double-story buildings. The tensile strengths are reported to be between 0.16 and 0.38 MPa for unstabilized rammed earth, and the incorporation of fibres and chemical stabilisers increases them to the range of 0.73 to 1.16 MPa. Furthermore, the seismic behaviour of rammed earth is affected by its shear strength, which is only a small fraction of compressive strength, ranging from 7% to 10%, and is dependent on cohesion and friction angle. This study also developed an expression for predicting the tensile strength of rammed earth based on the percentage of fibres and chemical stabilisers used.

3

Numerical investigation of thermal performance in a solar air heater using triangular fins

Bahlol Ahmed Qahtan, Mohammed Ansam Adil

Advances in Science and Technology. Research Journal

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2026

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Vol. 20, no. 8

221--235

EN

This research presents a study on improving the heat transfer of a flat solar collector system for air heating using triangular fin attached on the bottom face of an absorber plate in solar collector using a numerical simulation. A three dimensional numerical emulation was attained utilizing a Computer simulation of fluid flow via CFD process established on a k-ε disruption representative for renormalized array to predict the heat transfer improvement of flat solar collector system for air heating. The numerical results acquired into a constant thermal flux 1000 W/m² and the rang of Reynolds number is from 2349 to 9311 that were validated by comparing them with a practical data obtainable in the scientific published works. The numerical outcomes revealed that the use of triangular fins can effectively influence the thermal boundary layer by inducing periodic flow recirculation behind the fins. The numerical results also showed that at a Reynolds number of 5000 a maximum Nusselt number of 26.0 can be reached using a 10 mm fins but at the cost of a significant increase in the friction when applying a 15 mm fins. Consequently, the thermo-hydraulic coefficient of performance (THPF) for 10 mm fins was found to be greater than 0.88 for all Reynolds numbers, making it a better choice for a solar air heating system.

4

Relative thermo-hydraulic performance of mono and hybrid transformer nanofluid in a plate fin heat exchanger - An experimental study

Sandhya Devireddy, Sithebe Thembelani, Rao Veeredhi Vasudeva

Advances in Mechanical and Materials Engineering

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2026

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Vol. 43, nr 1

43--54

EN

This investigation conducts a comparative study on the thermo-hydraulic performance of magnesium oxide nanoparticles dispersed in transformer oil (MgO/TrO) and a hybrid nanofluid containing both magnesium oxide and copper oxide nanoparticles (MgO-CuO/TrO). Key performance metrics including Overall Heat Transfer Coefficient (UHTC), Convective Heat Transfer Coefficient (CHTC), Nusselt number (Nu), friction factor (FF), and pumping power (PP) were evaluated across relevant ranges of temperature (30-70 ̊ C) and Reynolds number. Results indicate that the hybrid (MgO-CuO/TrO) nanofluid consistently demonstrates significantly enhanced heat transfer characteristics. Compared to the MgO/TO fluid, the hybrid formulation exhibited superior UHTC up to 55% enhancement, CHTC 14-24% enhancement, and Nusselt number 4-27% enhancement. The hybrid nanofluid showed higher friction factors in the range of 8-11% and consequently required 2.2-3.8% greater pumping power under similar operating conditions. While the incorporation of CuO nanoparticles improves the thermal performance of the MgO-based transformer oil with an increased oil pumping power effect.

PL

W artykule przedstawiono wyniki analizy porównawczej właściwości termohydraulicznych nanocząstek tlenku magnezu rozproszonych w oleju transformatorowym (MgO/TrO) oraz hybrydowego nanopłynu zawierającego zarówno nanocząstki tlenku magnezu, jak i tlenku miedzi (MgO-CuO/TrO). Kluczowe parametry wydajności, takie jak całkowity współczynnik przenikania ciepła (UHTC), konwekcyjny współczynnik przenikania ciepła, liczba Nusselta (Nu), współczynnik tarcia oraz moc pompowania, oceniono w odpowiednich zakresach temperatur (30–70°C) i liczby Reynoldsa. Wyniki wykazały, że hybrydowy nanopłyn (MgO-CuO/TrO) wykazuje znacząco polepszone właściwości w zakresie przenikania ciepła. W porównaniu z płynem MgO/TrO, hybrydowa formuła charakteryzowała się lepszym współczynnikiem całkowitego współczynnik przenikania ciepła aż do 55%, konwekcyjnym współczynnikiem przenikania ciepła w zakresie 14-24% i liczbą Nusselta w zakresie 4-27%. Hybrydowy nanopłyn charakteryzował się wyższym współczynnikiem tarcia w zakresie 8-11%, i w konsekwencji wymagał o 2,2-3,8% większej mocy pompowania w podobnych warunkach pracy. W prowadzenie nanocząsteczek CuO poprawia parametry cieplne oleju transforma torowego na bazie MgO z jednoczesnym zwiększeniem wymaganej mocy pompowania.

5

Vapor absorption refrigeration under variable environmental conditions

Qandil Ahmed, Othman Ali, Abdellatif Nasser, Beithou Nabil, Khalid Mohammad Bani, Aljabarin Nader, Borowski Gabriel, Alsaqoor Sameh

Journal of Ecological Engineering

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2025

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Vol. 26, nr 3

381--389

EN

In this study, the Electrolux ammonia-water-hydrogen vapor absorption system (VAS) has been analyzed for cooling load with different heat transfer media. The performance of the VAS under variable environmental conditions was investigated. It has been concluded that a high heat transfer medium is essential to have a high COP system. The cooling load of air had a COP of about 0.31%, where water improved the COP to 15%. This study also indicated that moving from natural convection to forced convection improves the evaporator temperature from -10 °C to -11.6 °C. Mist water and mist ethanol improved the evaporator temperature to -12.8 °C and -13.7 °C respectively. This study emphasizes choosing suitable heat transfer medium with the VAS maximizes the COP of the system, it also indicates that better heat transfer from the condenser such as ground source heat exchanger or pool cooling condenser must be used instead of natural convection with air.

6

Integration of Green Roofs and Facades as a Climate Change Adaptation Strategy: Environmental, Energy, and Microclimatic Aspects

Kraus Michal, Senitkova Ingrid Juhasova, Zak Jaroslav, Kankovsky Ales

Inżynieria Mineralna

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2025

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Vol. 2, no. 2

art. no. 93

EN

The study examines the integration of green roofs and facades as an effective strategy for mitigating the adverse effects of climate change in urban environments. Urban areas face growing challenges due to the urban heat island effect, increased stormwater runoff, deteriorating air quality, and rising energy consumption. Green roofs and facades offer a sustainable solution by enhancing building performance and improving the surrounding microclimate through the natural benefits of vegetation. The research evaluates the technical and environmental advantages of vegetative roof and facade systems using detailed case studies and simulation models. Key findings demonstrate that green roofs and facades improve thermal insulation by reducing heat transfer through the building envelope, leading to lower indoor temperatures in summer and reduced heat loss in winter, which decreases the need for heating and cooling and results in lower energy consumption and greenhouse gas emissions. These systems also mitigate the urban heat island effect by absorbing solar radiation and cooling the surrounding air through evapotranspiration. Improved stormwater management is another benefit, as green roofs retain rainwater and slow runoff, reducing pressure on drainage systems and lowering the risk of flooding. Enhanced air quality is achieved through the capture of particulate matter and the absorption of pollutants such as carbon dioxide (CO₂) and nitrogen oxides (NOₓ). The study identifies key design parameters influencing performance, including substrate composition, plant selection, irrigation methods, and structural load capacity. A comparative analysis of extensive and intensive green roofs shows that extensive roofs, with shallow substrates and low-maintenance plants, offer adaptability and low maintenance but lower insulation, while intensive roofs, with deeper substrates and diverse plantings, provide higher insulation and greater biodiversity but require more upkeep. Green facades, especially those using hydroponic modular systems, have proven effective in reducing noise and air pollution while improving the building’s microclimate. The study concludes that integrating green roofs and facades represents a scalable and sustainable solution for enhancing urban resilience to climate change, offering significant environmental, economic, and social benefits.

7

Thermal transfer performance of downhole electric heaters for in-situ pyrolysis in tar-rich coal

Tang Ying, Xiao Li, Yang Fan, Wu Xiaodan, Su Zhan, Zhang Yue, Jiang Shixin, Yang Peng

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2025

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Vol. 73, nr 3

art. no. e153839

EN

The paper investigates the performance of a large-size helical baffle heater in an in-situ operation using a numerical simulation method. The study reveals that the fluid in the shell retains a spiral flow, and the output flow velocity is higher than in the surrounding area. However, the pitch design is big, resulting in a low-velocity flow zone on the backwind side. At 100 kW and 500 m3 /h, the fluid flow is turbulent. At 50 kW and 200 m3 /h, the fluid remains laminar. As the flow rate rises, the pressure of tar-rich coal formation grows dramatically. The wall temperature exhibits a spiral plunger at the inlet, but the bottom temperature is symmetrically distributed. Under low power and flow, Reynolds number change has a greater impact on the combination of Nusselt and Prandtl numbers. The wellbore experiences higher thermal loads during downhole heating, dramatically increasing the possibility of thermal damage. An increase in the heater shell length improves the total heat transfer performance. Conventional heaters often only heat the bottom formation. Therefore, while optimizing the construction, it is vital to ensure that the weight of the heater itself does not exceed the tensile strength of the cable and consider shifting down the perforation outlet or lowering the outlet.

8

Analytical modeling of the dynamic thermal behavior of stabilized compacted earth blocks walls for bioclimatic constructions

Mahdad M’hamed, Hammas Aghiles, Abboudi Said

Budownictwo i Architektura

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2025

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Vol. 24, no. 3

145--170

EN

The main challenge in bioclimatic constructions using compressed and stabilized earth blocks (CSEB) is determining the optimal external wall thickness to ensure good thermal comfort. This study investigates heat transfer through opaque walls made with various CSEB samples commonly used in Algeria, using the cyclic admittance method. Five homogeneous CSEB materials were evaluated based on several dynamic thermal parameters: admittance (Y), transmittance (U), surface factor (F), decrement factor (DF), and time lag (TL). Results showed that walls made with CSEB-2 material at 40 cm thickness had the best thermal performance. Additionally, multiple linear regression (MLR) analysis was applied to predict TL and U values, yielding high coefficients of determination (R² of 0.98 and 0.79, respectively). The study concluded that TL and U values are strongly influenced by wall thickness and the compaction energy of the CSEB samples.

9

Experimental studies on the thermal performance of MWCNT-based transformer oil in a plate-fin heat exchanger

Sandhya Devireddy, Sithebe Thembelani, Rao Veeredhi Vasudeva

Advances in Mechanical and Materials Engineering

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2025

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Vol. 42, nr 1

251--259

EN

In this paper, thermal performance of transformer oil enhanced with addition of multi-walled carbon nanotubes (MWCNTs) in a plate-fin heat exchanger is experimentally determined. In this investigation, a custom-built test rig, is employed to determine the overall heat transfer coefficient (UHTC) and friction factor. Thermo-physical properties of MWCNT based transformer oil are experimentally determined in the laboratory. From this investigation, the key findings indicate that adding MWCNTs up to 0.008% concentration significantly boosts thermal performance of oil, achieving notable increases in UHTC up to 34% as a function of mean bulk temperature of the nano-fluid taking mass flow rate a parameter. Likewise, there is 20% enhancement in convective heat transfer coefficient (CHTC) as a function of mass flow rate particularly at higher flow rates. However, this enhancement is coupled with few drawbacks in the context of fluid dynamics, such as the nanofluids exhibiting 3.8% increase in friction factor at low Reynolds numbers leading to 4.5% extra pumping power requirement when compared to the base fluid. MWCNT-transformer oil based nanofluids offer improved heat dissipation capacity and highlights the potential of these nanofluids to significantly improve thermal system performance, particularly at high flow rates, without incurring excessive pumping power demands.

PL

W niniejszym artykule eksperymentalnie określono parametry cieplne oleju transformatorowego wzbogaconego o wielościenne nanorurki węglowe w płytowo-żebrowym wymienniku ciepła. W badaniach wykorzystano specjalnie zbudowane stanowisko testowe do określenia całkowitego współczynnika przenikania ciepła i współczynnika tarcia. Właściwości termofizyczne oleju transformatorowego na bazie wielościennych nanorurek węglowych określono eksperymentalnie. Kluczowe wnioski z badań wskazują, że dodanie wielościennych nanorurek węglowych w stężeniu do 0,008% znacząco poprawia parametry cieplne oleju, osiągając znaczący wzrost całkowitego współczynnika przenikania ciepła nawet o 34% w funkcji średniej temperatury nanopłynu, biorąc pod uwagę masowe natężenie przepływu jako parametr. Podobnie, zaobserwowano 20% wzrost konwekcyjnego współczynnika przenikania ciepła w funkcji masowego natężenia przepływu, szczególnie przy wyższych natężeniach przepływu. Jednakże, ten wzrost wiąże się z kilkoma wadami w kontekście dynamiki płynów, takimi jak wzrost współczynnika tarcia nanopłynu o 3,8% przy małychliczbach Reynoldsa, co prowadzi do 4,5% dodatkowego zapotrzebowania na moc pompowania w porównaniu z płynem niemodyfikowanym. Nanopłyny na bazie oleju transformatorowego zawierającego wielościenne nanorurki węglowe oferują lepszą zdolność rozpraszania ciepła podkreślając potencjał tych nanopłynów w zakresie znacznej poprawy wydajności cieplnej układów, szczególnie przy wysokich natężeniach przepływu, bez nadmiernego zapotrzebowania na moc pompowania.

10

Numerical investigation of thermal performance in liquid cooling serpentine mini-channel heat sink with various inlet/outlet positions

Chadi Kamel, Belghar Nourredine, Lachi Mohammed, Khoshnaw Fuad

Advances in Materials Science

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2025

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Vol. 25, nr 3(85)

18--37

EN

This study aims to investigate and optimize the thermal dissipation of a constant heat flux source by conducting a numerical analysis of four serpentine mini-channel heat sink configurations, each characterized by different inlet and outlet arrangements for the cooling fluid. The cooling system under study consists of an upper part made of ABS copolymer resin, incorporating the fluid inlets and outlets (water), and a lower part made of aluminum, which contains the serpentine mini-channel heat sink. The analyzed configurations included four cases: First: a single inlet and a single outlet, Second: two inlets and one outlet, Third: one inlet and two outlets, and Fourth: a variation of the third model with reversed inlet and outlet positions. Numerical simulations, performed using the finite volume method, cover a Reynolds number range from 200 to 600. The analysis focuses on flow behavior, temperature distributions, pressure drop, thermal resistance, the average Nusselt number and the performance evaluation factor (PEF). The results indicate that the configurations with two inlets and one outlet (Case 2) and the reversed inlet/outlet configuration (Case 4) significantly enhance cooling compared to the other configurations. However, the two-inlet, one-outlet case also results in a higher pressure drop. At a Reynolds number of 600, Case 2 achieves the best thermal performance with an average Nusselt number of 20.79 and a minimum thermal resistance of 0.228K/W, while Case 3 exhibits the lowest efficiency. These findings help identify optimal configurations for cooling high heat flux electronic components.

11

Study of predictive control model for cooling process of mark III LNG bunker

Bao Guozhi, Qin Weiguang, Jiang Qingfeng, Pu Chunrong

Polish Maritime Research

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2024

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nr 3

102--112

EN

When loading liquefied natural gas (LNG) onto a dual-fuel LNG container ship fuelled by LNG, there is a considerable temperature difference between LNG and the fuel tank at room temperature. The current solution is to pre-cool the tank with LNG through a spray line but the cooling process, if not correctly handled, can result in excessive cooling rates and Boil-Off Gas (BOG), which can expose the tank to increased temperature stress and gas pressure. Therefore, this paper takes the Mark III fuel tank of a specific type of LNG container ship as the object and realises a real-time predictive control system by writing a UDF (User Defined Function) to simulate and analyse the influence of LNG spray rate on the change of cooling effect, cooling time and cooling cost under the unidirectional LNG spray cooling mode. Compared with the results of the fuel tank gas experiment, the deviation of numerical model simulation results is less than 5%. Under the same cooling rate, the real-time control scheme can achieve a more uniform cooling rate and reduce the total LNG consumption by 25%. With the increase in LNG cooling rate, the cooling time, LNG usage, and the total BOG exhaust volume all decrease; however, the decreased range gradually decreases as well. The results of this paper provide parameters and suggestions for optimising and improving the LNG fuel tank cooling monitoring and control system.

12

Enhancing Thermal Performance of Hot Storage Tanks through Chimney-Type Electric Heating and Natural Circulation

Beithou Nabil, Abdallatif Nassir, Khalid Mohammad Bani, Alsaqoor Sameh, Alahmer Ali, Borowski Gabriel, As’ad Samer, Attar Hani, Andruszkiewicz Artur

Advances in Science and Technology. Research Journal

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2024

|

Vol. 18, no. 3

151--160

EN

Hot storage tanks (HST) are known for their high energy consumption, attributed to variations in usage, heat dissipation within the tank, and heat losses to the surroundings. This study proposes a chimney-type electrically heated HST, which is investigated under static mode to enhance its thermal performance. Different natural circulation areas (chimney areas) with large (9.5 cm diameter), medium (2.5 cm diameter), and small (1.5 cm diameter) sizes were utilized to examine the effect of natural circulation on the HST performance. Additionally, the influence of chimney insulation on the HST performance was also studied. The experiments revealed that the chimney significantly affected the thermal stratification within the tank. Different chimney contact diameters (9.5 cm, 2.5 cm, and 1.5 cm) were tested, showing varying degrees of thermal stratification. The results indicated that smaller chimney contact diameters led to higher thermal stratification and more rapid heating of the top layer temperatures. However, the impact of insulation on thermal performance was inconclusive, suggesting the need for more effective insulation and further investigation into the dynamic mode of operation. The findings also highlighted the faster heating of the top outer layer compared to the larger diameter, emphasizing the significance of the chimney type electrical heater in the hot storage tank.

13

Experimental Investigation on Free Convective Heat Transfer Performance of Oxide Nanofluids Along a Vertical Cylinder

Ravi Babu S., Pradeep Kumar P., Basha S. A., Maruthi Rao M.

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 5

185--194

EN

The multi criterion decision making (MCDM) method and experimental investigation on free convective heat transfer performance of oxide-based water nanofluids along a vertical cylinder are the two methods used to compare the performance in this paper. Al2O3, CuO, TiO2, SiO2, Fe3O4, and ZnO were the metal oxide nanoparticles used in the study to make water-based metal oxide nanofluids with volume fractions ranging from 0% to 1%. Two step method was used to create nanofluids. Thermo-physical properties like density, specific heat, viscosity, and thermal conductivity were measured after the various nanofluids were synthesized. Then, the performance of each nanofluid was evaluated based on various attributes using the weighted sum model (WSM) method, and the ranking of nanofluids was given. To begin, water served as the medium for free convection heat transfer experiments to validate the experimental setup. Free convection heat transfer experiments were carried out using metal oxide-based water nanofluids as mediums at volume fractions ranging from 0% to 1% for various heat inputs in the range of 30 W and 50 W. The heat transfer coefficient augments with percentage volume concentration up to 0.1 % for all types of nanofluids and then decreases until it reaches 0.6% volume fraction. Al2O3-water nanofluid performs better than other metal oxide nanofluids in both WSM and experimental methods.

14

A review of enhancement of thermal performance of flat plate solar collectors through nanofluid implementation

Ali Zahra a H. Mohammed, Hussein Adnan M.

Advances in Mechanical and Materials Engineering

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2023

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Vol. 40, nr 1

139--148

EN

Nanofluids have found widespread practical applications in heat transfer, including cooling oils for diverse uses like automobile radiators, solar and nuclear power systems, biomedical devices, ventilation, heating, air conditioning, refrigeration, engine cooling, and transformers. Extensive scientific studies have investigated the impact of exotic fluids when combined with traditional heat transfer fluids, revealing that this combination enhances heat transfer performance beyond that of conventional working fluids. Collectively, these studies demonstrate the impressive heat transfer abilities of nanofluids. To optimize the efficiency of flat plate solar collectors, a comprehensive approach integrating theory and experimentation is essential. The results of such research highlight that increasing both the mass flow rate and concentration of nanofluids can lead to significant efficiency improvements, with potential enhancements ranging from 20% to 85%.

PL

Nanociecze znalazły szerokie praktyczne zastosowanie w wymianie ciepła. Oleje chłodzące w tym oleje stosowane są w różnych zastosowaniach, takich jak chłodnice samochodowe, systemy energii słonecznej i jądrowej, urządzenia biomedyczne, wentylacja, ogrzewanie, klimatyzacja, chłodnictwo, chłodzenie silników i transformatorów. Celem szeroko zakrojonych badań naukowych było zbadanie wpływu egzotycznych cieczy w połączeniu z tradycyjnymi cieczami przenoszącymi ciepło, ujawniając, że ta kombinacja poprawia wydajność wymiany ciepła w porównaniu z konwencjonalnymi cieczami roboczymi. Badania wykazały imponujące zdolności przenoszenia ciepła przez nanociecze. Optymalizacja wydajności płaskich kolektorów słonecznych polega na kompleksowym podejściu łączącym metody teoretyczne oraz badania eksperymentalne. Wyniki takich badań podkreślają, że zwiększenie zarówno masowego natężenia przepływu, jak i stężenia nanocieczy może prowadzić do potencjalnej poprawy wydajności w zakresie od 20% do 85%. Celem tego artykułu jest zaprezentowanie osiągnięć naukowych w zakresie implementacji nanocieczy do zwiększenia efektywności cieplnej płaskich kolektorów słonecznych.

15

Enhancement of thermal efficiency of nanofluid flows in a flat solar collector using CFD

Zarda Falah, Hussein Adnan Mohammed, Danook Suad H., Mohamad Barhm

Diagnostyka

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2022

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Vol. 23, No. 4

art. no. 2022411

EN

Flat plate solar collector (FPSC) is popular for their low cost, simplicity, and ease of installation and operation. In this work, FPSC thermal performance was analyzed. It's compared to diamond/H2O nanofluids. The volume percentage and kind of nanoparticles are analyzed numerically that validation with experimental data available in the literature. The hot climate of Iraq is employed to approximate the model. The numerical study is performed by using ANSYS/FLUENT software to simulate the case study of problem. Due to less solar intensity after midday, temperatures reduction. The greatest collector thermal efficiency is 68.90% with 1% ND/water nanofluid, a 12.2% increase over pure water. The efficiency of 1% nanofluid is better than other concentrations because of a change in physical properties and an increase in thermal conductivity. Since the intensity of radiation affects the outlet temperature from the solar collector and there is a direct link between them, this increases the efficiency of the solar collector, especially around 12:30 pm at the optimum efficiency.

16

Thermal performance analysis of manned airships in a thermally variable environment

Shi Hong, Liu Meinan, Chen Jiamin, Zou Yitao

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 5

art. no. e143105

EN

The safety and reliability of the manned airship depend to a considerable extent on its thermal performance. In this paper, heat balance equations are developed and solved in the C++ programming language. The temperature variation of the enclosure, gasbag, and nacelles of the manned airship is investigated. In addition, the effects of season, latitude, and orientation on the thermal performance of the manned airship and the airship nacelle are investigated. The results show that: (1) The average temperature difference of the nacelle surface at the same time is 25 K, while the maximum temperature difference in the nacelle is 29 K during the day, (2) the temperature distribution in the nacelle is similar in spring and autumn, with maximum temperature between 306 K and 309 K. The maximum temperature in the nacelle is between 300 K and 303 K in winter while the maximum temperature in the nacelles is between 309 K and 315 K in summer, (3) as the flight position of the manned airship changes from 20°N to 60°N, the average nacelle temperature varies slightly by about 1 K. However, as the latitude increases, the high- temperature region shifts from the bottom of the nacelle to the side of the nacelle, and (4) the temperature distribution of the upper envelope of the airship varies considerably with orientation. However, the average temperature of the nacelle is less impacted by orientation. These results are useful for understanding the thermal performance of manned airships.

17

Czerń w architekturze w aspekcie zrównoważonego rozwoju - Część 1

Gerlic Krzysztof

Builder

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2022

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R.26, nr 3

18--21

PL

Artykuł jest wprowadzeniem do badań dotyczących wpływu zastosowania materiałów budowlanych o ciemnych barwach w architekturze. Obecnie projektowanie architektoniczne kieruje się m.in. doktryną zrównoważonego rozwoju. Troska o zmiany klimatyczne zaleca kształtowanie środowiska zbudowanego tak, aby zapewnić najlepsze warunki dla osób przebywających w nim obecnie i w przyszłości. Badania środowiskowe potwierdzają wpływ materiałów budowlanych na mikroklimat przestrzeni zbudowanej i dlatego stanowią inspirację do analizy ich właściwości, a zwłaszcza współczynników odbicia i pochłaniania promieniowania słonecznego. Istotne jest również, dlaczego podejmowane są decyzje o stosowaniu bardzo ciemnych materiałów. Czy kreacja twórcy może to pomijać?

EN

The article is an introduction to research on the influence of the use of dark-colored building materials in architecture. Currently, architectural design is guided, among others, by the doctrine of sustainable development. Concern for climate change recommends shaping the built environment to provide the best conditions for people living now and in the future. Environmental research confirms the influence of building materials on the microclimate of the built space, hence the analysis of their properties, in particular the reflectivity and absorption of solar radiation. It is also important why decisions are made to use very dark materials. Can the designer creation skip this?

18

A comparative study for double pass solar air collector utilizing medial glass panel

Salih Hussein M.

Archive of Mechanical Engineering

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2022

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LXIX, nr 4

729--747

EN

A numerical investigation of thermal prediction of double-pass solar air heater of-counter flow is developed in the present study. The main idea of the current study is that the collector consists of two layers of glass so that the middle layer is glass instead of the usual metal plate. The performance of double-pass solar air heater is studied for a wide range of solar radiation intensities (600, 750 and 900 W/m 2). A FORTRAN-90 program is built to simulate the mathematical model of double-pass solar air heater based on solving steady state two-dimensional Navier-Stokes equations and energy equation based on finite volume method. Turbulence effect is simulated by two equations k-ε module. The results are compared with the results of a previous experimental study and a good agreement was found. From compression calculating efficiency of the present and traditional collector for each solar intensity, it was found that the efficiency of the current collector is higher than that of the traditional one, where the efficiency of the current collector at the solar intensity of (600, 750 and 900) W/m 2 are (0.529, 0.514 and 0.503), respectively, while those of the traditional collector (0.508, 0.492 and 0.481), respectively. In addition to this, the effect of the mass flow rate on the temperature difference of the current proposed collector was studied. Three values of the mass flow rate were studied (0.009,0.018, and 0.027) kg/s at solar intensity of 750 W/m 2. From this it was found that the temperature difference decreases with increasing mass flow rate. Accordingly, the efficiency decreases

19

An overview of heat transfer enhancement based upon nanoparticles influenced by induced magnetic field with slip condition via finite element strategy

Hafeez Muhammad B., Krawczuk Marek, Shahzad Hasan

Acta Mechanica et Automatica

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2022

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Vol. 16, no. 3

200--206

EN

The mathematical model of heat generation and dissipation during thermal energy transmission employing nanoparticles in a Newtonian medium is investigated. Dimensionless boundary layer equations with correlations for titanium dioxide, copper oxide, and aluminium oxide are solved by the finite element method. Parameters are varied to analyze their impact on the flow fields. Various numerical experiments are performed consecutively to explore the phenomenon of thermal performance of the combination fluid. A remarkable enhancement in thermal performance is noticed when solid structures are dispersed in the working fluid. The Biot number determines the convective nature of the boundary. When the Biot number is increased, the fluid temperature decreases significantly. Among copper oxide, aluminium oxide, and titanium oxide nanoparticles, copper oxide nanoparticles are found to be the most effective thermal enhancers.

20

Thermal and acoustic behavior of energy saving wall panel

Khan M. Yasir, Baqi Abdul, Sadique Rehan

Archives of Civil Engineering

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2021

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Vol. 67, nr 4

303--316

EN

Research and development of energy-efficient materials have been essential for sustainable infrastructure growth. A considerable amount of money is being spent on various energy stabilization techniques worldwide to attain thermal comfort in buildings. Thus, lowering the energy demand through green materials is vital to save energy and the environment. In this paper, a new form of Structural Insulated Panel (SIP) has been developed and referred to as Ferro Cellular Lightweight Concrete Insulated Panel (FCIP). Comparative thermal efficiency and acoustic performance of FCIP and brick masonry walls have been tested experimentally. The thermal results show that FCIP allows just 2ºC rise in the internal temperature of the room chamber in two hours, whereas the brick masonry allows 9.5ºC rise in the internal temperature of the room chamber for the same period. Similarly, the acoustic results show that FCIP has 0.85 sound absorption coefficient compared to 0.2 for brick masonry wall. Further, the cost-benefit analysis was conducted based on the electricity consumption results of a building produced by the eQuest energy simulation program. The outcome shows that the building’s lifetime running cost gets reduced to 50% when FCIP replaces the concrete/brick masonry envelope.