• Energy Research

This study aimed to enhance distilled water production by employing conventional single-slope solar distillers with continuous seawater input. Three solar absorbers—i.e., a flat absorber, an absorber with 10 fins, and an absorber with 15 fins—were designed and examined experimentally. The seawater entered the distillers continuously due to gravity. Moreover, the seawater level inside the distillers was kept constant by using a floating ball valve. The overall size of each distiller was fixed at 1136 mm × 936 mm × 574 mm. The performance of the distillers was analyzed and discussed. The average yields of the flat absorber, the absorber with 10 fins, and the absorber with 15 fins were 1.185 L/d, 1.264 L/d, and 1.404 L/d, respectively. The results of the absorber with 15 fins were about 18.5% higher than those of the flat absorber. The experimental results were compared with the established correlations. This new design with increased water yield provides an effective approach for harvesting sunlight in remote tropical regions for small-scale solar desalination.

The membrane electrode assembly (MEA) plays an important role in the proton exchange membrane fuel cell (PEMFC) performance. Typically, the structure comprises of a polymer electrolyte membrane sandwiched by agglomerate catalyst layers at the anode and cathode. Optimization of various parameters in the design of MEA is, thus, essential for reducing cost and material usage, while improving cell performance. In this paper, optimization of MEA is performed using a validated two-phase PEMFC numerical model. Key MEA parameters affecting the performance of a single PEMFC are determined from sensitivity analysis and are optimized using the response surface method (RSM). The optimization is carried out at two different operating voltages. The results show that membrane thickness and membrane protonic conductivity coefficient are the most significant parameters influencing cell performance. Notably, at higher voltage (0.8 V per cell), the current density can be improved by up to 40% while, at a lower voltage (0.6 V per cell), the current density may be doubled. The results presented can be of importance for fuel cell engineers to improve the stack performance and expedite the commercialization.

The increasing global demand for palm oil and its products has led to a significant growth in palm plantations and palm oil production. Unfortunately, these bring serious environmental problems, largely because of the large amounts of waste material produced, including palm kernel shell (PKS). In this study, we used computational fluid dynamics (CFD) to investigate the PKS co-firing of a 300 MWe pulverized coal-fired power plant in terms of thermal behavior of the plant and the CO2, CO, O2, NOx, and SOx produced. Five different PKS mass fractions were evaluated: 0%, 10%, 15%, 25%, and 50%. The results suggest that PKS co-firing is favorable in terms of both thermal behavior and exhaust gas emissions. A PKS mass fraction of 25% showed the best combustion characteristics in terms of temperature and the production of CO2, CO, and SOx. However, relatively large amounts of thermal NOx were produced by high temperature oxidation. Considering all these factors, PKS mass fractions of 10%–15% emerged as the most appropriate co-firing condition. The PKS supply capacity of the palm mills surrounding the power plants is a further parameter to be considered when setting the fuel mix.

Due to their high potential and beneficial characteristics, algae is considered as very promising energy source in future. In this study, an integrated conversion system of algae to hydrogen is pro ...

Abstract Hydrogen (H2) has been well studied for its potential use in energy storage, which is particularly related with the intermittent characteristic of renewable energy sources. However, the gas form of H2 at standard pressure and temperature (STP) poses a challenging problem in terms of storage, transportation, and low volumetric energy density. An effective and reversible method for H2 storage is chemically bonded H2 used in the toluene (C7H8)/methylcyclohexane (MCH, C7H14) cycle. This study investigates a power generation system from H2 storage in MCH, involving the dehydrogenation process and the combined cycle as a power generation process. An adequate analysis of the heat circulation was performed through an enhanced process integration (EPI) to ensure the high energy-efficiency of the proposed system. A highly endothermic reaction of dehydrogenation was supplied by utilizing the energy/heat from air-fuel combustion to ensure the effective heat recovery of the system. The proposed system was analyzed through an adjustment of the main operating parameters, namely, the GT inlet pressure, GT inlet temperature, and the condenser pressure, to observe their effects on the efficiency of the system. It was found that these parameters have a significant influence on the system performance and provide the possibility of further improvement. Under optimum conditions, the proposed system can realize a very high system efficiency of 54.6%. Moreover, the proposed system is also compared to a Graz cycle-based system, which has been reported to achieve an excellent power generation cycle from H2. This result implies that the proposed integrated system leads to a significantly higher power-generating efficiency. Numerically, the proposed system demonstrated a system efficiency of 53.7% under similar conditions as the Graz cycle based system, which achieved a system efficiency of 22.7%.

This work adopts the artificial neural network (ANN) for predicting the efficiency of a double-pipe heat exchanger which employs T-W tape inserts with different wing-width ratios (w/W) of 0.31, 0.47, and 0.63. The effects of friction factor (f), Nusselt number (Nu), and thermal performance (η) are predicted using the established multi-layer ANN. Different scenarios are examined using two parameters as inputs to the ANN: Reynolds number (Re) and w/W. The results prove that the developed ANN model is able to accurately predict the experimental data. The obtained mean square error has a value of less than 0.7 as compared to the experimental values. Furthermore, the proposed ANN-based approach is also effective to predict the thermal parameters, with the least variance and high precision. In addition, a multiple linear regression is employed to check the efficiency of the proposed model from which it is demonstrated that the suggested neural network method provides useful guidance for accurately predicting the thermal parameters with the least variance. The configuration of 2–10-1 is found to be the best for the current model, with a mean absolute error of 0.546896.

Abstract Hydrogen (H2) is considered as a clean energy carrier in the future with high efficiency and various utilization technologies. The H2 can be produced from biomass as primary energy source to reduce environmental impact. Currently, some projects are underway to achieve efficient conversion and reduce costs associated with H2 generation. High energy efficiency can be achieved by minimizing exergy loss through process integration and exergy recovery. In this study, co-production of H2 and power from black liquor (BL) is proposed based on process integration and exergy recovery. The proposed system consists of BL evaporation, gasification, syngas chemical looping (SCL), and power generation. The evaporation process employs exergy recovery using steam tube rotary evaporator. The effect of target moisture content on the evaporator performance is evaluated. Furthermore, the thermodynamics analysis of gasification is performed in circulating fluidized bed reactor based on Gibbs energy minimization. The SCL process comprises reducer, oxidizer and combustor and integrates with power generation. The result shows that the proposed integrated system can achieve higher efficiency of nearly 70%. In addition, the concentrated CO2 can be generated during the SCL process, avoiding additional cost for separation.