Dry anaerobic digestion (DAD) is an attractive method for the stabilization of solid organic waste with high solid concentration (22–40%). This article provides different aspects for bio-energy ...production through dry anaerobic digestion suggested by different researchers. Basic fundamental aspects like reactions occurring in the process, microbial species involved in the process, effect of feedstocks and operational parameters like pH, temperature, C/N ratio, VFA concentration, etc. with types of reactors are summarized. A number of scenarios and the effect of changing individual parameters of the environmental impacts of dry anaerobic digestion process for biogas production are considered. Mobility of mass nutrient and energy flow in the above said process are also parts of this review article. We conclude that long term research and development for improvement and optimization of operational parameters in dry anaerobic digestion is necessary.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The use of renewable energy systems for real life applications has been increasing for the last few decades due to the growing concern about the global warming and environmental pollution. The ...renewable energy sources are clean and freely available in the nature, however, the efficient utilization is still a cause of concern among the scientific and business communities. This paper presents an extensive literature review on both the energy and exergy analyses of typical renewable energy systems including, solar thermal, solar photovoltaic and biomass cookstove. Some important conclusions from the literature survey has been drawn and summarized in this paper. Among all important aspects studied and summarized in this paper, it is found that most of the analysis carried out for renewable energy systems so far is based on the energy analysis. Also for all renewable energy systems, the performance based on exergy analysis, in general, is found to be lesser than that of the energy analysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Phase change materials (PCMs) utilized for thermal energy storage applications are verified to be a promising technology due to their larger benefits over other heat storage techniques. Apart from ...the advantageous thermophysical properties of PCM, the effective utilization of PCM depends on its life span. Moreover, PCMs which are utilized for different solar thermal energy storage applications are required longer thermal and chemical stability for the extended performance of a system. This review shows the in-depth details on thermal stability and reliability of different PCMs such as organic, inorganic, eutectics, and composites materials for heat storage applications. Different methods for measuring the thermophysical properties along with the classification of PCMs based on applications and temperature ranges have been discussed. This paper also covers the selection criteria and commercial viability of PCMs for different domestic and industrial applications. In addition to this, the effect of thermal cycle testing on the properties of different organic, inorganic, eutectic, and composite PCMs has been summarized. The present article can be highly useful for researchers and practice engineers in the areas related to thermal energy storage applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The performance of evacuated tube collector with/without storage was investigated.•Evacuated tube collector with phase change material showed better performance.•Designed system is suitable for ...day/night time utilization of hot water.•Thermal cycle test of SA-67 has been studied for long term stability.
This manuscript presents an experimental investigation of heat pipe evacuated tube solar collector with and without phase change material for water heating application under the same weather conditions. In this study, a comparative analysis of two systems has been done in the same weather condition. Where evacuated tubes of the first system (evacuated tube collector-A) were left without phase change material and second system (evacuated tube collector-B) was integrated with SA-67 as phase change material. In order to ensure the thermal and chemical stability of the selected phase change material, thermal cycling treatment was carried out. The results showed that SA-67 has excellent chemical and thermal stability even after 1500 thermal cycling treatment.
In order to analyze the thermal performance of the designed systems, the experiment was conducted with five different water flow rates (8, 12, 16, 20 and 24 L per hour). The daily thermal efficiency of evacuated tube solar collector with and without phase change material was varied in the range of 42–55% and 79–87% respectively. Although, the daily energy efficiency of evacuated tube collector integrated with phase change material was 37.56%, 35.31%, 36.69%, 32.34%, and 32.73% higher than evacuated tube collector without phase change material for water flow rates of 8, 12, 16, 20 and 24 L per hour respectively. The daily thermal efficiency for both systems was maximum at the flow rate of 20 L per hour. The heat transfer parameters for the designed systems have also been evaluated and compared.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Comprehensive review on heat transfer, device design and limitation of Concentrated Photovoltaic Thermal system.•Component wise thorough discussion on design and limitations of Concentrated ...Photovoltaic Thermal system.•Discussion on economic feasibility and recent novel applications of Concentrated Photovoltaic Thermal system.•Presents recent trends and move in Concentrated Photovoltaic Thermal system research.
The need of the hour in present world scenario is to reduce the emission of greenhouse gases and environmental pollution whilst satisfying the world energy demands. The most promising and readily available source of energy over the whole world is solar energy. One of the ways of taping this energy into useful energy is using Concentrated Photovoltaic Thermal systems. The paper presents the advanced comprehensive review on the design components of Concentrated Photovoltaic Thermal, heat transfer medium, recent application area such as Tissue Dyeing, domestic hot water, Organic Rankine Cycle, and the economic aspect of the Concentrated Photovoltaic Thermal system. Furthermore, the review paper simplifies the classification into two systems namely thermally coupled and thermally decoupled systems. Concentrated Photovoltaic Thermal shows potential to deliver better gains compared to Concentrated Photovoltaic, Photovoltaic and Photovoltaic Thermal. But matching the different components like the heat transfer component and the medium for specific use is an area that requires research. Therefore, this review concentrates more on the advantages and limitations of using different heat transfer components and heat transfer medium. The benefits of this paper would be the understanding of the components of the heat transport system like fins, microchannel, storage tank and underground heat exchangers and the fluid used in the Concentrated Photovoltaic Thermal integrated system like water, air, nanofluids, Phase Change Materials. It is found that the heat transfer device performance is limited due to its large area, thermal losses, mirror effect on the thermal and electrical efficiencies, and the temperature difference between the sink and device. Likewise, the performance of the heat transfer fluid is dependent on the mass flow rate, thermal mass, viscosity, density, time and the required temperature. Finally, for economic feasibility of the Concentrated Photovoltaic Thermal system requires the need for a grid connected system with properly sized system with feed-in-tariff and carbon incentives. Furthermore, the recommendation for heat transfer device, medium and economic aspect is also presented. However, more experimental research is required to further understand the compatibility of each components with Concentrating Photovoltaic Thermal System as presented in way forward.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Defects in planar and vertically oriented nanographitic structures (NGSs) synthesized by plasma enhanced chemical vapor deposition (PECVD) have been investigated using Raman and X-ray photoelectron ...spectroscopy. While Raman spectra reveal the dominance of vacancy and boundary type defects respectively in vertical and planar NGSs, XPS provides additional information on vacancy related defect peaks in the C 1s spectrum, which originate from non-conjugated carbon atoms in the hexagonal lattice. Although an excellent correlation prevails between these two techniques, our results show that estimation of surface defects by XPS is more accurate than Raman analysis. Nuances of these techniques are discussed in the context of assessing defects in nanographitic structures.
Defects in planar and vertically oriented nanographitic structures (NGSs) synthesized by plasma enhanced chemical vapor deposition (PECVD) have been investigated using Raman and X-ray photoelectron spectroscopy.
The excessively available solar energy storage is a very useful way to bridge the energy demand and its supply gap. This thermal energy storage (TES) can be done in the form of sensible or latent ...heat energy. The energy storage in the form of latent heat energy is better than the sensible energy storage in terms of operating temperature and storage density. Organic PCMs (O-PCMs) have great potential, especially from low to medium temperature-TES applications due to their several admirable thermal and physical characteristics. An appropriate melting point/enthalpy of O-PCMs is mainly required parameters for TES applications. In this regard, development of eutectic O-PCMs (EO-PCMs) by mixing two or more PCMs customizes the melting temperature and enthalpy so that they can be made suitable for targeted TES applications. However, their low thermal conductivity and leakage issue during the phase transition significantly restrict the practices of EO-PCM. A lot of studies were carried out to solve these changes by preparing them in form stable or shape-stabilized composite form. This review paper provides an insight on the development and thermo-physical properties of eutectic (binary and ternary) EO-PCMs as well as their composites as nano-enhanced and form stable phase change materials (FSPCMs). This paper also highlights recent studies published about the enhancement of thermal conductivity of EO-PCMs and their FSPCMs developed for LHTES practices. The use of EO-PCMs and their form stable composites in various applications, and challenges faced are also discussed. Finally, it outlooks the future directions for development of eutectic organic PCMs and their applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Experimental performance has been carried for developed solar water heater.•Stearic acid as phase change material has been investigated under both modes.•Proposed system is suitable for domestic & ...industrial applications.•Phase change material integrated manifold is designed for thermal energy storage.•System was investigated with different mass flow rates under both modes.
In this study, the thermal performance of a novel solar collector integrated with stearic acid as phase change material has been investigated. In this design, the solar radiation was collected by heat pipe equipped evacuated tubes and then stored in manifold integrated with phase change material. The stored thermal energy of phase change material then transferred to water flowing through bundle of finned copper pipes placed inside the manifold. In present study, the design, the operating principle and the experimental investigation of the developed system have been presented. The developed system was investigated with different mass flow rates and also discussed the influence of varying mass flow rate on the thermal performance of system. The experimental investigation of designed and developed system has been carried out for two modes i.e. mid-day charging mode and full-day charging mode. It has been observed that for considered mass flow rates, thermal efficiency of the system was varied in the range of approximately 52–62% for full-day charging mode while for mid-day charging mode, it was varied between 55 and 72%. The maximum value of thermal efficiency was approximately 72.52% at mass flow rate of 24 LPH for mid-day charging mode. The efficiency of phase change material for both modes was varied in the range of approximately 61–64%. The annual cost and annual fuel cost of the developed system are much lower than conventional system. Also, the initial capital cost for the developed system can be recovered after 6 years of operation. However, there is no recovery of initial investment for electricity based water heating system.
The proposed system overcomes two problems associated with conventional heat pipe evacuated tube solar collector: elimination of heat pipe overheating problem and low thermal conductivity of phase change materials. By this novel design of manifold, the influence of thermal stratification on the thermal performance of solar collectors can be completely eradicated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In recent years the visible impact of the release from wet cooling tower to the atmosphere has become a matter of greater concern. In the past visible plumes were accepted as the inevitable ...consequence of industrial activities and a sign of thriving manufacturing industry. Plumes from combustion plant may be visible and colored for a variety of reasons. Some are associated with the combustion process itself, such as excessive quantities of nitrogen dioxide causing a brown tinge to plumes or the release of small particles, and/or aerosols, in the plume which scatter light. These factors can be tackled by modification of the combustion process and the introduction of emission control technology. However, the most common cause of plume visibility, and the reason that chimneys attract public attention, is the presence of condensed water vapor in plumes. In this paper attempt has been made to present an overview of the previous research work on the plume from wet cooling towers, which describes the previous work done of few researchers on the formation, potential and abatement of plumes besides, the numerical analysis of wet cooling towers for a typical set of operating parameters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► Calcium chloride hexahydrate (CaCl2⋅6H2O) as a PCM was used in this study. ► Two different capsulated system (HDPE based panel and balls) were designed. ► The results of CaCl2⋅6H2O are very ...attractive for space air conditioning. ► Energy and exergy analyses for space cooling applications.
This communication presents the experimental study of PCM based thermal management systems for space heating and cooling applications using energy and exergy analysis. Two different types of based thermal management system (TMS-I and TMS-II) using calcium chloride hexahydrate as the heat carrier has been designed, fabricated and studied for space heating and cooling applications at a typical climatic zone in India. In the first experimental arrangement the charging of PCM has been carried out with air conditioning system while discharging has been carried out using electric heater for both the thermal management systems. While in the second arrangement the charging of PCM has been carried out by solar energy and the discharging has been carried out by circulating the cooler ambient air during the night time. In the first experiment, TMS-I is found to be more effective than that of TMS-II while it was found to be reverse in the case of second experiment for both the charging and discharging processes not only for energetic but also for the exergetic performances.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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