Experimental and numerical analysis of a compact indirect solar dehumidification system
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Baffle
Chemical energy
Endothermic process
Energy transformation
Thermal energy
Thermochemical cycle
Concentrated solar power
Solar Power
Cogeneration
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The comparison of different energy recovery systems employed on a spray dryer is challenging. This work compares two cases with a base case of a dryer alone, to identify any available improvements and interpretation of the factors used within exergy analysis, for system-wide optimisation. While exergy analysis results indicate natural gas boiler systems (case 1) are superior to compressor-driven recovery systems (case 2) (13% better evaporation efficiency), this paper demonstrates the significant potential to improve either system, and that dryers are one of the limiting units within the process (38% exergy improvement potential). The improvement potential for both cases is quite high (~90% of total added exergy), particularly as the inlet gas temperature increases. This paper demonstrates a method of simplifying exergy analysis to make it more accessible to engineers as a tool for optimising thermal and non-thermal systems that include a dryer as a significant part of the system.
Exergy efficiency
Limiting
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An experimental study was undertaken of damping produced by single flexible-ring baffles in a 396-cm diameter tank of liquid nitrogen. Two 24.8-cm wide baffles were tested. One baffle was 0.00635 cm thick type 301 stainless steel and the other 0.0254 cm thick Teflon FEP. Each baffle produced damping of liquid oscillations equal to or greater than that expected from rigid baffles of the same size. The equations used to determine the baffle thickness required were found to be adequate baffle design equations.
Baffle
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Exergy is a measure which can commonly deal with the quantification of the variety of resources, products and energy coming in and going out the systems in manufacturing process. In this study, exergy consumption analysis was performed on ceramic parts. The exergy of the intrinsic to the materials and energy were calculated and then the degree of process efficiency (defined as the ratio of fixed energy to input in this report) was evaluated. Results revealed that the process efficiency was 5.5% in total, suggesting that the most part of input exergy was lost as a thermal enthalpy and wastes. Particularly, a lot of exergy was consumed and the process efficiency was low in granulation and sintering steps, then, the approaches to improve the efficiency were discussed.
Exergy efficiency
Granulation
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Exergy efficiency
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Drying is a complex process involving simultaneous heat and mass exchanges, and it is considered one of the oldest unit operations performed for preserving agricultural products. This process requires a significant amount of energy, and researchers have conducted different studies to improve energy efficiency, reduce drying time and preserve product quality. Dryers based on solar energy have gained more space, as this energy source is free and abundant. Thermal energy storage techniques can increase the reliability of solar energy for drying. These techniques allow the stored energy to be used in periods of no solar incidence. The complex processes involving each element of the solar drying process have made experiments quite expensive. Several studies have bet on the use of advanced techniques of computer simulation to minimize this problem. Studies have shown the effectiveness of using these techniques for different solar dryers, achieving satisfactory results. Therefore, this study aims to provide parameters, address different types of dryers, and emphasize the importance and methods of thermal energy storage. In addition, this study also addresses the use of computational numerical modeling to verify the phenomena of heat and mass transfer in drying systems and thermal energy storage.
Thermal energy
Solar dryer
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Avoidable endogenous/exogenous parts of the exergy destruction in the components of an energy conversion system can be computed by applying advanced exergy analysis. Their calculation is crucial for the correct assessment of the real thermodynamic enhancement achievable by the investigated energy conversion system. This work proposes a new approach to estimate the avoidable exergy destruction rates of system components, being more rigorous compared to the conventional method due to the elimination of the need for the implementation of theoretical assumptions associated with the idealization of processes. An open-source web-based interactive tool was implemented to contrast the results of the conventional advanced exergy analysis to those involving the new approach for avoidable exergy destruction estimation. The comparison was based on the same case study, i.e., a refrigeration system selected from the literature. It was observed that the developed tool can be properly employed for comparing the two approaches within exergy analyses, and the results obtained presented some differences for the compressor and the condenser. Compared to the new approach, the existing methodology of advanced exergy analysis suggests lower values of the avoidable part of exergy destruction, which can be reduced by improving the efficiency of the compressor and the condenser. Moreover, the avoidable parts of exergy destruction, which could be removed within these components by improving the efficiencies of the remaining components, were higher in the case of the application of the existing advanced exergetic analysis as compared with the findings obtained by the proposed approach. These differences were due to the impossibility of the existing advanced exergy analysis to implement complete thermodynamic “idealization” for the condenser and evaporator.
Condenser (optics)
Exergy efficiency
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The comparison of different energy recovery systems employed on a spray dryer is challenging. This work compares two cases with a base case of a dryer alone, to identify any available improvements and interpretation of the factors used within exergy analysis, for system-wide optimisation. While exergy analysis results indicate natural gas boiler systems (case 1) are superior to compressor-driven recovery systems (case 2) (13% better evaporation efficiency), this paper demonstrates the significant potential to improve either system, and that dryers are one of the limiting units within the process (38% exergy improvement potential). The improvement potential for both cases is quite high (~90% of total added exergy), particularly as the inlet gas temperature increases. This paper demonstrates a method of simplifying exergy analysis to make it more accessible to engineers as a tool for optimising thermal and non-thermal systems that include a dryer as a significant part of the system.
Exergy efficiency
Limiting
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