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The existing roofing system in tropical climates is not adapting to the worsening climate, along with the demand for sustainable building design; this study introduced a pioneering cool roof system to reform the traditional roofing system. The pioneering cool roof system is composed of white reflective coating, hollow foamed concrete roof (HFCR) tile, and a sustainable active reflective insulation (RI) system. Despite the complex integrated roof technologies, the study adopted 3D CFD numerical simulation for an in-depth and frontier thermal distribution analysis and fluid flow presentation. The outcomes of the numerical model were compared with field measurements for validation purposes, which resulted in just a 3.31% error. The internal attic was 35.64 °C despite the roof exterior achieving 54.59 °C after receiving an average 680 W/m2 solar radiation source. After the heat flux was hugely terminated by the HFCR tile and sustainable active RI system, the heat flux magnitude attained in the internal attic was 1.0822 W/m2, and the active RI system removed 96.29% of heat flux excellently. Meanwhile, the proposed roofing design's energy-saving performance was 27.5%.

The penetration of increasing solar gain towards the building deteriorates the building's thermal quality and raises cooling demand. In particular, the roof receives the most solar gain. The roof system reformation is urged to improve the roof system's heat capacity and conserve building energy. This paper introduced a novel cool roofing system to replace the traditional roof system. The proposed novel cool roofing applications merged: (i) lightweight foam concrete, (ii) hollow concrete slab, (iii) white cooling paint and (iv) active reflective insulation system powered by solar energy. The discovery of the proposed system was evaluated with experimental chambers exposed to the outdoor environment. Under intense sunlight, the internal roof surface was 30.6 % cooler (50.5 °C to 35.0 °C). The mean attic temperature achieved was 33.9 °C under a field where the daily maximum recorded surrounding temperature is 43.0 °C. In contrast with a bare roof at 41.9 °C, the proposed design demonstrated a 19.2 % lower solar gain, achieving a sub-ambient structure. Besides that, the cooling demand simulation generated similar cooling demand savings (20 %). Significantly, this comprehensive cool roofing system exhibited a considerable and constructive outcome in cooling the buildings by achieving sustainable development to create a better and more environmental future for all.

Large scale of hydrogen storage is needed to balance the energy supply-demand fluctuation issues. Among few of the large scale storage systems, depleted oil and gas wells are widely employed. The construction of wellbore is normally in cylindrical shape and formed by layers of cement, casing and formation. As failure of wellbore is costly, proper structural integrity assessment is essential. In this article, an analytical solution derived based on recursive algorithm for estimating the thermomechanical stresses across the wellbore structure was proposed and verified. The temperature and stresses distribution results obtained from proposed analytical solution were compared with numerical results and they were found in good agreement. The percentage of difference was observed to be less than 0.1%. Besides that, a comparison study was performed on two, four and six layers wellbore structure. It was observed that four and six layers structure can produce much lower tangential tensile stress on the steel casing of the wellbore.

The cooling load is the most prominent building energy consumption. The roof's poor thermal resistance effect causes buildings in the tropical climate to receive high solar heat that afterwards transfer to the attic before entering the living space. Eight roof design models were built and evaluated under 90 min of solar radiation exposure to noon-time level solar intensity to determine their cooling effect at noon every day. Significantly, the fantastic cool roof system was proven effective with a structural heat gain reduction of 85.5%. The reduction of concrete's density from 2500 kg/m3 to 1100 kg/m3 with lightweight foamed concrete technology allowed the roof's lower surface temperature to decrease by 21.6% (66.3–52.0 °C). Adding a highly solar reflective insulation system with roof ventilation reduced the structural heat gain by up to 33.3%. The combination effects of lightweight foamed concrete roof tile, hollow longitude sections, thermal reflective coating, reflective insulation system, and renewable solar-powered fans reduce the peak attic temperature from 42.8 °C to 32.2 °C.

This study aims to optimize the flow channel design for a proton exchange membrane electrolyzer cell (PEMEC) to minimize the pressure drop across the cell. The pattern of parallel flow channels is considered with a dual-porous layer structure sandwiched between the flow channel plate and the catalyst layer. Four geometric factors are considered in the optimization analysis, including the width of the flow channel, the depth of the flow channel, the particle diameter of the large-pore porous layer, and the particle diameter of the small-pore porous layer. Computational fluid dynamics (CFD) is used to simulate the flow field, and based on the results of the CFD simulation, the Taguchi method is employed to analyze the optimal flow channel design. The importance of the factors is further analyzed by the analysis of variance (ANOVA) method. Three inlet velocities are assigned in the Taguchi analysis, which are 0.01, 0.1332, and 0.532 m/s, and then an orthogonal array is constructed and analyzed for each inlet flow condition. It is found that the optimal combination of the factors is the depth of the flow channel 1 mm, the width of the flow channel 3 mm, the particle diameter of the large-pore porous layer 0.212 mm, and the particle diameter of the small-pore porous layer 0.002 mm. The pressure drop across the PEMEC is minimized at the condition with the optimal combination of the factors. The ANOVA analysis shows that the depth of the flow channel exhibits the most significant impact on the pressure drop, while the other factors play minor roles only.

Rubberwood biomass ash (RWA), which was derived from the combustion of rubberwood biomass in a fuel factory, was obtained for reuse as a natural mineral filler substitute in water-based intumescent coatings. The specific surface area of the RWA was 3.10 m2/g, with the particle's surface areas predominant composed of mesopores, which was justified using the Brunauer–Emmett–Teller Test (BET). Rubberwood ash coatings (RWAC) formulated with 3.0 wt% RWA exerted the most homogenous and durable surface matrix in the Accelerating Weathering Test (AWT). Fire-resistant test (FRT) and thermogravimetric analysis (TGA) demonstrated the incorporation of the RWA with the intumescent flame-retardant formulation, generated positive effects in equilibrium end temperature, thermal decomposition, and weight loss reductions. These effects are most prominent in the RWAC-3, which was comprised of 3 wt% RWA, and 50/40/7 wt% vinyl acetate (VA)/intumescent flame retardant additive (IFRA)/pigment. The RWAC-3 showed the lowest equilibrium end temperature at 131.4 °C, the lowest thermal degradation at 71 wt%, and the highest carbonaceous char formation at 12.8 mm. The Surface Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX) results exhibited a dense, compact, and coherent char formation for the RWAC-3 sample. The abundant O and P crosslinking structures in the RWAC-3 contributed to the quality of the char barrier. These results are supported by the evidence from Fourier-Transform Infrared Spectroscopy (FTIR), and X-Ray Diffractometer (XRD), which revealed the stretching of the O–H, P–O–C, and PO molecular functional groups, and the presence of thermally stable phosphate compounds in the RWAC-3.

The utilization of wastes in concrete as bio-based aggregate can alleviate disposal issues as well as preserve precious natural resources. This research highlights the wet grout binder derived from different water-cement ratios (0.65, 0.85, 1.05, and 1.25) in modifying the surface of lightweight bio-based coarse aggregate (LWBCA). In this research, the strength properties of lightweight aggregate concrete (LWAC) mixed with modified LWBCA were evaluated. The outcomes showed that through the replacement of non-treated bio-based aggregate with that of pre-treated grout coating bio-based aggregate, the density of the samples slightly increased. The results indicated that the slump value of the treated LWBCA showed a significant enhancement by almost 45% at 10 min for treated dura oil palm shell at 0.65 water-cement ratios (TDOPS/0.65), as compared to the non-treated bio-based aggregate. In addition, the strength of the TDOPS/0.65 mix shows more appropriate quality enhancement of pre-treated LWBCA when compared to non-treated, and correspondingly the strength properties of the concrete, particularly the significant increment of compressive strength and elastic modulus were recorded at 21% and 31%, respectively. Based on the water absorption test assessment, the LWBCA concrete indicated that good concrete was obtained for all the mixes. Therefore, a new technique of surface modification on bio-based aggregate has shown to be a highly suggested method, which performs as one of the most promising solutions to enhance the interfacial bonding strength. Thus, treatment improves the bio-aggregates to a level without scarifying the quality of the LWAC and substantially mitigating the environmental impact in concrete.

Waste Heat Recovery System (WHRS) technology, e.g., Organic Rankine Cycle (ORC) has been explored as a solution to the increase in geothermal potential, possibly applied in binary or combined form, as a single-flash plant. This approach utilizes waste brine obtained from the separator. The purpose of this study, therefore, was to determine the performance of R134a refrigerant on ORC systems, using scroll-expander. The experiment was conducted with motor different frequency, at 7.5 Hz, 10 Hz, 12.5 Hz, 15 Hz, 17.5 Hz, and 20 Hz, evaporator temperature regulation of 95 °C, condenser at 10 °C, and an initial working fluid pressure of 5 bar. The results showed modifications in the ORC system performance with scroll-expander, alongside the motor frequency, which influenced the net power and energy efficiency. In addition, the maximum speed produced by the expander was 505.8 rpm, while the highest for energy efficiency achieved from the system was 3.17%, at a motor frequency of 7.5 Hz, with a resulting net power of 584.5 Watt.

The global increase in world population is followed with a rise in waste generation and energy needs in various sectors. Organic waste, also known as biomass, is the most substantial contribution of the waste generation and it also can be utilized in energy generation. Therefore, the purpose of this study is to analyze the syngas production from co-gasification using Renewable Densified Fuels (RDF) with gasification temperature, lower heating and gas emission values, on the performance of the biomass co-gasification process in an open-top downdraft fixed bed gasifier. In this study organic waste used woods, coconut fibers and rice husks in pellets to blend the compositions of raw materials during the co-gasification process. The method used is the co-gasification technique with feed pellets WCF (wood-coconut fiber) and RH (rice husk) in various compositions, for example: 100% WCF, with 0% of RH, 75 WCF: 25 RH, 50 WCF: 50RH, 25 WCF: 75RH and all 100% RH with 0WCF. Furthermore, the syngas testing was directly measured on the burner with TCD type Shimadzu 8A gas chromatography. The result showed that the highest reactor temperature in the pyrolysis zone is 700 °C–900 °C which was significantly stable at 800 °C with oxidation temperature of 1000 °C–1100 °C. Furthermore, the result of the synthetic gas showed that the highest lower heating value of 100% WCF pellet composition at 3.582 kJ/Nm3 and lower heating value of RDF blending composition (75:25) at 3.392 kJ/Nm3. The increase in pellet fuels also leads to a rise in the LHV syngas value. These results produced a visually low tar content and ash particles in all compositions by approximately 30–35% of the initial mass, with the lowest ash in 100% WCF pellets composition at 0.25 g.

Concrete is one of the broadly used construction materials in the construction industry. This research intends to recommend the replacement of conventional coarse aggregates with recycled lightweight expanded clay aggregate (LECA) which offers several advantages such as lightweight, low cost, and easy availability. Lightweight concrete (LWC) offers numerous benefits; therefore, many researchers are using lightweight aggregate to produce lightweight structural composites concrete to compensate heavy loads by reducing the concrete self-weight due to lower density of lightweight concrete, improving in thermal properties and fire resistance, saving the cost of transportation and handling of precast units in the site. Different percentages (0, 0.15, 0.30, and 0.45%) of volume fraction of barchip polypropylene (BPP) fibre have been incorporated to improve the mechanical properties of lightweight aggregate concrete (LWA) concrete. In this study, the mixture of crushed lightweight expanded clay aggregate (CLECA) and barchip polypropylene (BPP) fibre have been used to achieve compressive strength between 28 and 37 MPa at 28-days with an oven-dry density ranged between 1900 and 2000 kg/m3. It is found that the inclusion of BPP fibres at an optimum volume fraction concrete enhances the compressive strength, splitting tensile strength and modulus of rupture. The compressive strength of the lightweight aggregate concrete containing 0.45% volume fraction of BPP fibre (CLLWAC-BPP0.45%) had achieved the highest compressive strength of 37 MPa at 28-days with a significant increment of about 31% compared to plain concrete. Hence, the findings of this research showed that the development of eco-friendly lightweight structural composites can be used as an alternative solution for conventional lightweight concrete, infrastructure and marine fields application.

The performance of a plate heat exchanger (PHE) using water as the working fluid with zigzag flow channels was optimized in the present study. The optimal operating conditions of the PHE are explored experimentally by the Taguchi method, with effectiveness as the objective function. The results are further verified by the analysis of variance (ANOVA). In addition, the zigzag flow channel geometry is optimized by the non-dominated sorting genetic algorithm-II (NSGA-II), in which the effectiveness and pressure drop of the PHE are considered the two objective functions in the multi-objective optimization process. The experimental results show that the ratio of flow rates is the most important factor affecting the effectiveness of the PHE. The optimal operating conditions are the temperatures of 95 °C and 10 °C at the inlets of hot and cold water flows, respectively, with a cold/hot flow rate ratio of 0.25. The resultant effectiveness is 0.945. Three geometric parameters of the zigzag flow channel are considered, including the entrance length, the bending angle, and the fillet radius. The sensitivity analysis of the parameters reveals that a conflict exists between the two objective functions, and multi-objective optimization is necessary for the zigzag flow channel geometry. The numerical simulations successfully obtain the Pareto optimal front for the two objective functions, which benefits the determination of the geometric design for the zigzag flow channel.

This cool roof system focuses on utilization of rainwater harvesting systems by integrating the smart sensor to cool the roof and attic temperatures for the improvement of comfort level of building occupants. An ideal cool roof technology system is basically made up of these three components: (1) moving-air-cavity (MAC) ventilation, (2) solar-powered fan and (3) rainwater harvesting system. These three main components integrate to perform and control the cool roof system. Four small-scale cool roof models were designed and constructed to inspect the performance of the rooftop and attic temperatures. The experimental work was carried out indoors by employing the halogen lamp as the replacement for solar irradiation, while the ambient temperature is monitored to be around 29.8 °C throughout the test. The temperatures of the rooftop surface, MAC aluminum tube, and attic region were measured by K-type thermocouples to evaluate the performance of the cool roof designs. The solar-powered fans were incorporated into the MAC, which accelerated the airflow rate within the cavity and rejected the hot air out before transferring it to the attic region. Meanwhile, an innovative rainwater harvesting system was executed to cool the rooftop temperature rapidly by reducing the rate of heat transfer to the attic region. The result of this inventive cool roof system (Design Z) has successfully reduced the attic temperature by 10.8 °C compared to the normal metal deck roof model (Design W). The findings of the project revealed that the integrated cool roofing technology system comprises the ability to enhance the comfortability of building occupants toward a long-term sustainable development for a better world.

Global energy demand is rising due to the rapid development and adoption of new technologies in every sector. Hence, there is a need to introduce a clean energy source that does not cause damage to the environment. Aluminium-air battery with its high theoretical specific volumetric capacity is an exciting alternative for post-lithium energy storage and has been at the forefront of energy research for years. However, the conventional aqueous electrolyte-based aluminium-air battery with bulky liquid storage, parasitic corrosion of aluminium in contact with the electrolyte, and formation of a passive oxide or hydroxide layer has precluded its widespread application. In order to achieve successful simplification and cost-effectiveness, a novel idea of a polypropylene-based aluminium-air battery is proposed. In this work, a polypropylene-based aluminium-air battery was constructed using aluminium foil as an anode, carbon fiber cloth as an air-cathode, and Polypropylene and Kimwipes as the separator. The effects of the electrolyte concentration on the aluminium-air battery were investigated and analyzed using various discharge currents. The study showed that the performance of the polypropylene separator is better than that of the Kimwipes separator. The battery capacity is negatively correlated with the concentrations of the electrolyte. At a discharge current of 30 mA, the aluminium-air battery has a specific capacity of 375 mAh g−1 when 1 M of potassium hydroxide was used as electrolyte.

This paper presents a novel cool roof technology system that promotes both passive and active cooling methods in reducing the attic temperature of the building. The project aimed to evaluate the effect of various roof model designs on the heating load to establish the capacity of a cooling roof system by maintaining the thermal comfort level for occupants in the buildings. There are four main components in constructing the cool roof models: 1) metal deck roof, 2) lightweight foam concrete roof, 3) moving-air-cavity (MAC) ventilation, and 4) solar-powered fan. Four small-scale cool roof models were built to evaluate the performance of each cool roof design. The performances of the roof surface and attic temperatures of each designed cool roof models were compared with the conventional metal deck roof. The roof models were conducted indoors by using halogen spotlights. The result of the Roof Design IV with the integration of lightweight foam concrete, MAC, and solar-powered fans has effectively reduced the attic temperature by 6.0°C compared with the normal roof model (Roof Design I). As a result, this integrated cool roof design comprises the ability to enhance the comfortability of occupants toward long-term sustainable development with the utilization of renewable energy to protect the natural environment.

The printed circuit heat exchanger (PCHE) is a promising waste heat recovery technology to improve energy efficiency. The current investigation presents the experimental results on the thermal performance of a novel PCHE for low-temperature waste heat recovery. The novel PCHE was manufactured using precision machining and diffusion bonding. The thermal performances, such as effectiveness and NTU values at different temperatures, are evaluated, and water is used as a working fluid. The experimental results indicate that the PCHE’s effectiveness is around 0.979 for an inlet flow temperature of 95 °C. The predominant factors affecting the thermal performance of the PCHE are the inlet flow temperature and the flow rate of the working fluid. In addition, a comparison of the experimental results and the literature shows that the effectiveness of the PCHE is better than the others, which have fewer layers of PCHE fins.

This research aims to evaluate the performance of a fluidized bed boiler in an ethanol production plant through exergy and irreversibility analysis. The study also includes the optimization of the pre-heater and the deaerator in order to improve the system efficiency. Operational data from the ethanol production plant was collected between 2015 and early 2016. The total exergy derived from the fuel was determined to be 7783 kJ/s, while the exergy efficiency of the system was found to be 26.19%, with 2214 kJ/s used in steam production, while 71.55% was lost to component irreversibility and waste heat from the pre-heater. The exergy efficiencies of individual components of the system such as the boiler, deaerator, and pre-heater were found to be 25.82%, 40.13%, and 2.617%, respectively, with the pre-heater having the lowest efficiency. Thus, the pre-heater has the highest potential to significantly improve the efficiency of the boiler system. The optimization of the pre-heater shows that a rise in temperature in the outlet of the pre-heater positively affects the exergy efficiency of the deaerator.

The objectives of this study are to perform the exergy analysis and ambient temperature optimization of the Kamojang geothermal power plant by employing Engineering Equation Solver (EES). The geothermal capacity is 55 MW and the field is vapor-dominated reservoir with temperature 245 °C. In the initial state temperature, pressure and mass flow data are collected from the plant operation. The study results show that system has overall efficiency of 35.86% which means that only 111,138.92 kW electrical power can be extracted from 309,000 kW thermal power being produced by 10 production wells of Kamojang. This low efficiency is due to irreversibility associated with different processes and components in the system. The largest irreversibility occurs in condenser due to which 53% of total energy is disposed into the environment. Ambient temperature at Kamojang varies from 17 to 20 °C. The effect of this variation in temperature is also investigated and it is observed that higher temperature does not have any significant impact on system efficiency.

Large scale of hydrogen storage is needed to balance the energy supply-demand fluctuation issues. Among few of the large scale storage systems, depleted oil and gas wells are widely employed. The construction of wellbore is normally in cylindrical shape and formed by layers of cement, casing and formation. As failure of wellbore is costly, proper structural integrity assessment is essential. In this article, an analytical solution derived based on recursive algorithm for estimating the thermomechanical stresses across the wellbore structure was proposed and verified. The temperature and stresses distribution results obtained from proposed analytical solution were compared with numerical results and they were found in good agreement. The percentage of difference was observed to be less than 0.1%. Besides that, a comparison study was performed on two, four and six layers wellbore structure. It was observed that four and six layers structure can produce much lower tangential tensile stress on the steel casing of the wellbore. [ABSTRACT FROM AUTHOR]