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Several techniques for cooling mass concrete structures were developed in order to increase structural integrity and reduce the influence of cement hydration, which sometimes causes cracking in concrete structures, negatively affecting their durability. This research focuses on cooling system design, initial investment, and the influence of different refrigerants on cooling system performance aims in producing higher quality massive concrete. Cooling aggregates in massive concrete structures such as desert dams can be performed by employing cooled air from an air conditioning duct system or chilled water. The experimental study illustrates the relationship between the coefficient of performance COP, the evaporator temperature, cooling capacity, and refrigerant mass flow rate as a function of the evaporator temperature, cooling capacity, and refrigerant mass flow rate. The findings of the experiments were utilized to verify a numerical model developed utilizing engineering equation solver (EES) software. The performance of the vapor compression of the cooling systems was compared using alternative refrigerants, including R22, R32, and R410a at different operating conditions. This study revealed that R22 refrigerant has a higher coefficient of performance than R32 and R410A, while R32 has the highest cooling capacity among other refrigerants.

Lightweight aggregate concrete (LWAC) exhibits the advantages of thermal insulation, reduces energy consumption building costs, improves building efficiency and easy construction. Furthermore, the utilization of industrial wastes in concrete is advantageous in terms of environmental sustainability. In order to explore this, several researchers investigated the idea of integrating industrial wastes in LWAC. However, the lack of knowledge regarding the performance of industrial waste-based lightweight aggregate concrete hinders the adaptation of this concept and application of LWAC in the construction sector. Therefore, this paper summarizes the research in relation to the sustainable LWACs containing oil palm shell (OPS), lightweight expanded clay aggregate (LECA), vermiculite, perlite, pumice and sintered fly ash as lightweight aggregate, along with industrial wastes and strength-enhancing additives (viz. fibers, polymers, etc.). Firstly, desirable physical, chemical, morphological and mineralogical characterization of different lightweight aggregates are presented, and then a comprehensive overview on fresh, hardened, durability and thermal properties of LWAC incorporating industrial wastes are discussed in comparison with normal weight concrete. The review also highlights the current challenges and suggests the research gaps for further development of eco-friendly LWAC. It is concluded that vermiculite, perlite, pumice, OPS, sintered fly ash and LECA with some suitable industrial waste materials have the potential to be used in the construction sector. Moreover, LWAC with industrial waste has 50–65% lower carbon emission (kg CO2 eq/m3) in the environment. The scientific contribution of this paper provides insights into different LWACs and the knowledge base for future research and paradigm shift of using LWACs as more common alternative building materials.

In this paper, the thermodynamic (energy and exergy) analysis and water analysis of a modified solar still augmented with copper tube heat exchanger in coarse aggregate have been carried out and compared with conventional still performance under the same climatic conditions. Basin water temperature, solar intensity, wind velocity, cumulative yield, water conductivity, total hardness, pH value and fluoride concentration are obtained from experimental results for saline, basin and distilled water. Energy efficiency, evaporation and convective heat transfer coefficient, exergy evaporation rate and exergy efficiency are determined from energy and exergy analysis. The results show that the modified still has an efficiency of 28% and 17% greater than the conventional still. The productivity of modified and conventional still is 6.23 kg m −2 and 2.41 kg m −2 , respectively. The exergy efficiency depends on the time of the test day and reaches a maximum value of 5.5% and 1.1%, respectively, for the modified and conventional still. From the water analysis, it is observed that the maximum distilled water pH, water conductivity, hardness and fluoride content are 7.5, 0.8 × 10 −4  S m −1 (0.8 µS cm −1 ), 0.5 × 10 −3  kg m −1 (0.5 mg L −1 ) and 0.7 × 10 −3  kg m −3 (0.7 mg L −1 ), respectively, with the still salinity removal efficiency of 99%. The results indicate that the modified still has higher energy and exergy efficiencies and better water quality with cumulative yield.

The global energy crisis demands efficient electricity production solutions, especially for isolated communities where hydraulic energy can be harnessed sustainably. This paper presents a case study analyzing the efficiency of a 13,330 kW hydrogenerator, consisting of a bulb-type hydro-aggregate using the calorimetric method—a viable alternative when testing at nominal load is not feasible due to technical limitations. The method involves measuring the thermal energy absorbed by the cooling water under three operating conditions: no-load unexcited, no-load excited, and symmetric three-phase short-circuit. Measurements followed IEC standards and were conducted with high-precision instruments for temperature, flow, voltage, and current. The results quantify mechanical, ventilation, iron, and copper losses, as well as additional losses via radiation and convection. Thermal analysis revealed significant heat accumulation in the rotor and stator windings, indicating the need for improved cooling solutions. The calorimetric method enables efficiency evaluation without interrupting generator operation, offering a valuable tool for diagnostics, predictive maintenance, and informed decisions on modernization. Furthermore, integrating an intelligent operational control system could enhance efficiency and improve the quality of the supplied energy, supporting long-term sustainability in hydroelectric power generation.

In response to the problem of high energy consumption caused by inefficient temperature control of energy storage aggregates in traditional building envelope structures, this study developed a decanoic acid–stearic acid composite phase-change ceramsite aggregate to improve the thermal performance of buildings and promote the utilization of solid waste resources. Based on the theory of minimum melting, composite phase-change materials were screened through thermodynamic models. The capric acid–stearic acid (CA-SA) melt system, whose theoretical phase-transition temperature falls within the building indoor thermal environment control range (18–26 °C), was preferred as the experimental object of this study, and its characteristics were verified through step cooling curves and thermal property tests. Subsequently, the ceramsite adsorption process was optimized, and the encapsulation process was studied. Finally, the encapsulation performance was evaluated through thermal stability and stirring crushing rate tests. The results showed that the phase-transition temperature of the decanoic acid–stearic acid melt system was 24.83 °C, which accurately matched the indoor thermal environment control requirements. The ceramsite particles treated by a physical vibrating screen can reach equilibrium after 30 min of adsorption at room temperature and pressure, which is both efficient and economical. The encapsulation layer of sludge biochar cement slurry with a water–cement ratio of 0.5 and a biochar content of 3% has both thermal conductivity and encapsulation integrity. The thermal stability test showed that the percentage of leakage of sludge biochar cement slurry and epoxy resin encapsulated aggregates was 0%, and the thermal stability rating was “very stable”. However, the percentage of leakage of unencapsulated and spray-coated encapsulated aggregates was as high as 193% and 40%, respectively. The results of the mixing and crushing rate test show that although the mixing and crushing rate of sludge biochar cement slurry encapsulation is slightly higher, its production cost is much lower than that of epoxy resin, and it is also environmentally friendly. This study improves the thermal performance of buildings by using composite phase-change ceramsite aggregate, and simultaneously realizes the resource utilization of sludge biochar, providing a solution for building energy saving and efficiency that combines environmental and engineering value.

The paper presents an approach to use the associated gases from geothermal water deposits for electric and thermal energy cogeneration in centralized distribution systems.

The need to construct environmentally friendly buildings to meet current environmental and ecological standards is urgent. This study introduces a new multi-layer construction material with two outer layers of ordinary mortar and an inner layer of a pozzolane-limes composite to meet this need. The thermal efficiency of this material in building construction is investigated using TRNSYS18 simulations for two distinct climatic zones in Morocco, with a particular focus on its impact on heating dynamics. The primary objective is to evaluate the thermal performance of multi-layered pozzolanic materials, for which mortar samples are meticulously prepared as a reference in the two different climatic zones (Azilal and Errachidia). Using the asymmetric hot plate method under both stable and transient conditions, the authors conduct thermal characterization experiments. The results underscore the improvement in thermal performance made possible by the incorporation of pozzolan as an aggregate in the multi-layer material compared to ordinary mortar. Specifically, thermal conductivity improves significantly, from 0.735 W m−1 K−1 for ordinary mortar to 0.4 W m−1 K−1 for multi-layered pozzolanic materials, representing a 46% mass gain. Additionally, effusivity decreases from 730 to 604 J m−2 K−1 s−1/2, while diffusivity decreases from 3.78 to 2.23 × 10−7 m2 s−1, further attesting to the material’s thermal efficacy. TRNSYS18 simulations corroborate the viability of using multi-layered materials as building envelopes, revealing potential annual heating gains of 25% in Azilal and 5% in Errachidia. These findings underscore the promising prospects of integrating these materials into sustainable construction practices.

This article introduces a novel nature-inspired algorithm called the Plum Tree Algorithm (PTA), which has the biology of the plum trees as its main source of inspiration. The PTA was tested and validated using 24 benchmark objective functions, and it was further applied and compared to the following selection of representative state-of-the-art, nature-inspired algorithms: the Chicken Swarm Optimization (CSO) algorithm, the Particle Swarm Optimization (PSO) algorithm, the Grey Wolf Optimizer (GWO), the Cuckoo Search (CS) algorithm, the Crow Search Algorithm (CSA), and the Horse Optimization Algorithm (HOA). The results obtained with the PTA are comparable to the results obtained by using the other nature-inspired optimization algorithms. The PTA returned the best overall results for the 24 objective functions tested. This article presents the application of the PTA for weight optimization for an ensemble of four machine learning regressors, namely, the Random Forest Regressor (RFR), the Gradient Boosting Regressor (GBR), the AdaBoost Regressor (AdaBoost), and the Extra Trees Regressor (ETR), which are used for the prediction of the heating load and cooling load requirements of buildings, using the Energy Efficiency Dataset from UCI Machine Learning as experimental support. The PTA optimized ensemble-returned results such as those returned by the ensembles optimized with the GWO, the CS, and the CSA.

Purpose The purpose of this study is to investigate whether increases in homeowner green amenities occurred because of income tax credits to the degree that changes in housing prices are measurable. Are higher incomes, lower mortgage rates and green income-tax credits impacting housing price changes? Design/methodology/approach The paper uses the least-squares regression model with natural log specifications. The log of income and a dummy variable, which was assigned to the Energy Policy Act (2005) and the American Recovery and Reinvestment Act (2009) coverage dates are used as independent variables. Two regression models were examined using monthly housing price data from January 1990 through the year 2018. The first regression model used a single dummy variable for credits available under the Policy Act of 2005 and the Recovery Act of 2009. The second regression model considered the credits granted under these two laws separately. Disposable income per capita impacts demands for housing while green upgrade expenditures affect the cost of housing. Findings The laws set low credit limits of $500 followed by $1,500 but because of the multiplier effect, the spending appears to have magnified and been much higher. The credit availability variables have positive coefficients and were significant at 1 per cent. This implies that single-family housing prices were sensitive to the existence of residential energy property income-tax credits. The R2 results were 0.93 or above for both models. Research limitations/implications The data used was aggregated and publicly available online. Many studies use aggregated macroeconomic data when modeling housing prices using the exogenous variable of disposable income but there is no substitute for examining individual homes by location and their sales price to see under what conditions green income-tax credits have the most impact. There could be demographic issues that are missed when using aggregated information. Practical implications Spending on heating/cooling systems, dual pane windows and other green amenities keeps the housing stock modernized and housing prices steady or rising. An additional benefit is that spending motivated by self-interest can simulate household consumption spending. Houses deteriorate due to wear and tear. Physical-repairable depreciation represents a situation where maintenance funds are continuously needing to be spent. Repairs and upgrades to the structure of the property keep its price stable by stopping the physical depreciation that would otherwise occur with the passage of time. Social implications The paper provides support for the idea that residential green amenity upgrades positively impact the value of a house. These green-amenity upgrades, which other research studies have suggested should be included explicitly in the appraisal process, are a major characteristic of a property when a price estimate is being done. Housing being sold should have a section on the information sheet noting the property green upgrades that exist and an energy efficiency score should be assigned to each house listed for sale. Originality/value There are few (if any) academic research papers studying the impact of green tax credits available under the Energy Policy Act (2005) and under the American Recovery and Reinvestment Act (2009). The degree to which green income-tax credits stimulate spending on housing has not been addressed by researchers. This paper is an initial research attempt to quantify whether these legislative efforts measurably encouraged homeowners to adopt newer, greener technologies.

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