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Abstract Double and added double stage organic Rankine cycle systems are configured to recover exhaust gas waste heat of dual fuel engines. To evaluate the performance of the models proposed here, energy, exergy and economic analyses are performed. Several working fluids are evaluated for recommendation for double and added double stage organic Rankine cycle systems. In the double stage organic Rankine cycle, cycle 1 and cycle 2 are connected in parallel. Working fluids R123, R141b, and R601 are used in cycle 1, and R245fa, R236ea, and R1233zd in cycle 2. In the double stage organic Rankine cycle, the working fluid combinations of R601-R1233zd, R601-R245fa and R123-R245fa show better performance when considering power, heat transfer area and payback period, which are 1760 kW, 2108.9 m2 and 4.21 year, respectively for R601-R245fa. In the added double stage organic Rankine cycle, cycle 1 and cycle 2 are connected in two stages and cycle 1 and cycle 3 in parallel. The net power of the working fluid combinations of R123-R245fa and R123-R1233zd are 1799 kW and 1782 kW, respectively, which are higher than those of the others. Further, for R123-R245fa, the heat transfer area and payback period are 3352 m2 and 6.20 year, respectively, which is better compared to those of other working fluid combinations.

Abstract Waste heat recovery has attracted a significant attention because of the world growth in energy demand. In this paper, we report the study on an energy recovery system utilizing low-grade waste heat below 100 °C. This system called a thermal-driven electrochemical generator is composed of reverse electrodialysis (RED) power generation and thermal separation using waste heat. We especially focus on the experimental characterization of the RED process with ammonium bicarbonate (NH4HCO3) solution, which is known to be easily decomposed at the temperature around 60 °C. We characterized this NH4HCO3-RED system with various parameters including the concentration difference, the membrane type, the inlet flow rate, and the compartment thickness. We found the best power density at the concentrated solution of 1.5 mol L−1 and the diluted solution of 0.01 mol L−1. The maximum power density increases as the inlet flow rate increases or the compartment thickness decreases owing to the decrease in the internal resistance. We obtained the excellent power density of 0.77 W m−2, compared with the previous studies.

Abstract Catalytic ethanol steam reforming (ESR) offers a sustainable and attractive route for hydrogen production, which can be utilized as a substitute for fossil fuels. ESR for hydrogen production involves complex reactions and yield of hydrogen depends upon several process variables such as temperature, molar feed ratio and pressure. In this study, a thermodynamics analysis coupled with experimentation for ESR toward hydrogen production has been investigated. The structured montmorillonite (MMT) nanoclay and TiO2 supported catalyst incorporated by nickel (Ni) was developed via a sol-gel and impregnation methods. The catalyst samples were characterized by XRD, FE-SEM, EDX, BET and TGA to understand crystallinity, surface morphology, pore structure and stability. Initially, thermodynamic analysis was employed to study the effect of reaction conditions on equilibrium product distribution of ESR. The equilibrium concentrations of different compounds were calculated by the method of direct minimization of the Gibbs free energy. Optimum conditions for ESR were found to be; atmospheric pressure, temperatures between 600 and 700 °C and steam to ethanol (S/E) feed molar ratio of 10:1, at which highest hydrogen can be produced with minimum coke formation. Next, catalytic performance of NiO/MMT-TiO2 catalyst for enhanced ESR for hydrogen production was conducted in a tubular fixed bed reactor at 500 °C and atmospheric pressure. Noticeably, Ni-promoted TiO2 NPs found efficient for selective hydrogen production, yet MMT-supported Ni/TiO2 gave much higher ethanol conversion with improved hydrogen yield. Using 12% Ni-10% MMT/TiO2 catalyst, ethanol conversion of 89% with H2 selectivity and yield of 61 and 55%, respectively were obtained. The stability test revealed MMT-supported catalysts maintained activity even after 20 h. By comparing results, it was possible to explain deviations between thermodynamic analysis and experimental results regarding carbon deposition and selective hydrogen production.

Abstract Many countries committed themselves in the Kyoto protocol to reduce greenhouse gas (GHG) emissions. Some of these targeted emission reductions could result from a switch from coal-fired to gas-fired electricity generation. The focus in this work lies on Western Europe, with the presence of the European Union Emission Trading Scheme (EU ETS). For the switching to occur, several conditions have to be fulfilled. First, an economical incentive must be present, i.e. a sufficiently high European Union Allowance (EUA) price together with a sufficiently low natural gas price. Second, the physical potential for switching must exist, i.e. at a given load, there must remain enough power plants not running to make switching possible. This paper investigates what possibilities exist for switching coal-fired plants for gas-fired plants, dependent on the load level (the latter condition above). A fixed allowance cost and a variable natural gas price are assumed. The method to address GHG emission reduction potentials is first illustrated in a methodological case. Next, the GHG emission reduction potentials are addressed for several Western European countries together with a relative positioning of their electricity generation. GHG emission reduction potentials are also compared with simulation results. GHG emission reduction potentials tend to be significant. The Netherlands have a very widespread switching zone, so GHG emission reduction is practically independent of electricity generation. Other counties, like Germany, Spain and Italy could reduce GHG emissions significantly by switching. With an allowance cost following the switch level of a 50% efficient gas-fired plant and a 40% efficient coal-fired plant in the summer season (like in 2005), the global GHG emission reduction (in the electricity generating sector) for the eight modeled zones could amount to 19%.

Despite the high energy demand in the industrialized world and the pollution problems caused by widespread use of fossil fuels, the need for developing renewable energy sources with less environmental impacts are increasing. Biodiesel production is undergoing rapid and extensive technological reforms in industries and academia. The major obstacle in production and biodiesel commercialization path is production cost. Thus, in previous years numerous studies on the use of technologies and different methods to evaluate optimal conditions of biodiesel production technically and economically have been carried out. In this paper, a comparative review of the current technological methods so far used to produce biodiesel has been investigated. Four primary approaches to make biodiesel are direct use and blending of vegetable oils, micro-emulsions, thermal cracking (pyrolysis) and transesterification. Transesterification reaction, the most common method in the production of biodiesel, is emphasized in this review. The two types of transestrification process; catalytic and non-catalytic are discussed at length in the paper. Both advantages and disadvantages of the different biodiesel production methods are also discussed.

Abstract Recently, biodiesel has been gaining market share against fossil-origin diesel due to its ecological benefits and because it can be directly substituted for traditional diesel oils. However, the high cost of the raw materials required to produce biodiesel make it more expensive than fossil diesel. Therefore, low-priced raw materials, such as waste cooking oil and animal fats, are of interest because they can be used to drive down the cost of biodiesel. We have produced biodiesel from camel fat using a transesterification reaction with methanol in the presence of NaOH. The experimental variables investigated in this study were the temperature (30–75 °C), reaction time (20–160 min), catalyst concentration (0.25–1.5%), and methanol/fat molar ratio (4:1–9:1). A maximum biodiesel yield of 98.6% was obtained. The fuel properties of biodiesel, such as iodine value, saponification value, density, kinematic viscosity, cetane number, flash point, sulfur content, carbon residue, water and sediment, high heating value, refractive index, cloud point, pour point, and distillation characteristics, were measured. The properties were compared with EN 14214 and ASTM 6751 biodiesel standards, and an acceptable level of agreement was obtained.

Abstract In this present work, green and efficient utilization concepts in the form of the use of an external magnetic field have been applied to improve catalytic performance in CO2 hydrogenation. The 10Fe 10Cu catalysts with two types of supports, core–shell and infiltrate mesoporous silica-aluminosilicate materials, were applied under external magnetic fields of different intensities (0, 20.8 mT, 27.7 mT) and orientations (north-to-south (N–S), south-to-north (S–N) directions). It was found that a magnetic field considerably enhanced both CO2 conversion and methanol and DME selectivities. The highest CO2 conversion was obtained over 10Fe 10Cu/infiltrate catalyst under the magnetic field conditions of 27.7 mT and 4N–S direction at 260 °C (conversion was 1.5 times greater than that without a magnetic field). Under such conditions and at 240 °C, the highest methanol and DME space time yields were obtained, with results 1.8–1.9 times higher than those of without a magnetic field. These excellent performances could be ascribed to the superior adsorption of CO2 and H2 reactant gas molecules over the surface of magnetized catalysts under external magnetic field. This leads to the advantages of the catalyzed CO2 hydrogenation–decreases in the operating temperature and simultaneous reduction in CO2 emission to the atmosphere. This therefore facilitates a carbon-neutral route of CO2 utilization.

Abstract The alternative energy sources in general and hydrogen based energy in particular have been currently grabbing great attention. Hydrogen is an efficient green source for power generation owing to its huge energy content. The operational costs and the hydrogen output are the key factors in the selection of a certain technique for the hydrogen production industrially. This study summarizes a new route for hydrogen production starting from a bit complicated hydrogen-containing molecules. Particular attention is given during this work towards a direct pyrrolysis catalytic conversion of long chains n-paraffin into hydrogen with in-situ production of nano-structured carbon particles. The simultaneous isomerization of the n-paraffin contented in the feedstock is also discussed during this process. This research study had provided new advances in the hydrogen production based on carrying out the production process at non-severe conditions namely; low operational temperatures and no pressure was applied. The introduction of a meso-porous molybdenum oxide catalyst for the catalytic hydrogen production is also a point of novelty for the presented work. Promising results have been disclosed at the end of this investigation; approximately 60 wt.% of the feedstock was converted to fuel gases while nearly 30 wt.% of the feed had turned as nano-carbon species. The hydrogen productivity had been detected as high as 42 wt.% of the original feedstock. This in fact might provide a new platform of the hydrogen production throughout the conversion of wax by-products. In comparison to two commercial catalysts, the hydrogen yield obtained by the prepared catalyst in this work had heavily scored.

Ever-growing construction industries worldwide require energy saving, environmental friendly, inexpensive, and thermally efficient materials. Driven by this demand, we evaluated the thermal performance and economy of a newly developed PCM called local paraffin. These PCMs as potential thermal energy storage (TES) systems were extracted from Iraqi crude petroleum waste product and encapsulated in the building construction. Two identical test rooms were constructed by incorporating such paraffin (40% oil + 60% wax) on the roof and walls for determining its effect on the heat transfer over the temperature range of 40–44 °C. Experiments were conducted for achieving the controlled comfort temperature of 24 °C (below the PCM melting temperature). Room without PCM encapsulation was demonstrated to consume higher energy at 24 °C than the one with PCM. The energy economy of the PCM incorporated room was assessed by comparing the estimated electricity cost with the building that contains the traditional air conditioning system. Analytical calculation was performed to validate the experimental results. These paraffin based TES systems were established to be suitable alternative for efficient and green energy implementation in the building design for hot climate nations.