Thermodynamic Analysis of Steam Cooling Process in Marine Power Plant by Using Desuperheater

Application of artificial neural network method for prediction of osmotic pretreatment based on the energy and exergy analyses in microwave drying of orange slices

Energy and exergy analysis of hydrogen production by solid oxide steam electrolyzer plant

An energy and exergy analysis of the condensate pump from the marine steam propulsion system during the condensate leakage between pump stages is presented in this paper. Measurements from the steam propulsion system during exploitation were necessary for collecting all the data for the condensate pump analysis. Due to condensate leakage inside the pump casing, the producer specified condensate pressures at the pump outlet could not be obtained during the exploitation. Low condensate pressure at the pump inlet and condensate temperature slightly above the atmospheric significantly influences the pump exergy analysis. Increase in pump load resulted in an increase of pump energy and exergy losses and efficiencies. In the observed load range during the leakage, pump energy losses are between 19.88 kW and 24.78 kW, while pump energy efficiencies are between 11.12 % and 41.54 %. Pump exergy losses are slightly higher, while exergy efficiencies are slightly lower when compared to energy losses and efficiencies. During normal operation, without leakage, the pump energy efficiencies are from 5 % to 20 % higher in comparison with pump operation when the leakage occurs.

An energy and exergy analysis of the condensate pump from the marine steam propulsion system during the condensate leakage between pump stages is presented in this paper. Measurements from the steam propulsion system during exploitation were necessary for collecting all the data for the condensate pump analysis. Due to condensate leakage inside the pump casing, the producer specified condensate pressures at the pump outlet could not be obtained during the exploitation. Low condensate pressure at the pump inlet and condensate temperature slightly above the atmospheric significantly influences the pump exergy analysis. Increase in pump load resulted in an increase of pump energy and exergy losses and efficiencies. In the observed load range during the leakage, pump energy losses are between 19.88 kW and 24.78 kW, while pump energy efficiencies are between 11.12 % and 41.54 %. Pump exergy losses are slightly higher, while exergy efficiencies are slightly lower when compared to energy losses and efficiencies. During normal operation, without leakage, the pump energy efficiencies are from 5 % to 20 % higher in comparison with pump operation when the leakage occurs.

The dairy industry needs new and more energy-efficient technological procedure for milk pasteurization. This article introduces a comparative efficiency assessment of various milk pasteurization technologies and electrotechnological means. The study featured milk, which was heated from 20 to 75°C with a capacity of 1000 kg/h at an estimated power of 58.95 kW. The treatment involved a steam-to-milk pasteurizer with electric indirect or direct heating, an induction pasteurizer, and a thermosiphon pasteurizer with direct or indirect electric heating. The study relied on the methods of energy and exergy analyses. The system of steam-to-milk pasteurizer with electric indirect (elemental, induction) or direct (electrode) heating demonstrated the following indicators: exergy loss – 1.29 kW, power consumption – 71.29 kW, exergy efficiency – 0.99, energy efficiency – 0.827. The thermosiphon pasteurizer with direct or indirect electric heating demonstrated the following properties: exergy loss – 1.29 kW, power consumption – 60.92 kW, exergy efficiency – 0.99, energy efficiency – 0.9676. The induction pasteurizer had the least competitive parameters: exergy loss – 10.8 kW, power consumption – 70.43 kW, exergy efficiency – 0.867, energy efficiency – 0.837. The thermosiphon pasteurizer with direct or indirect electric heating was able to increase the energy efficiency of milk pasteurization, while the induction pasteurizer proved to be a promising R&D direction.

In this study, exergy analysis, energy analysis, and mathematical modeling are performed in a 35 MW solar‐fossil fuel power plant. The losses of exergy and energy in different components and also changes of the efficiency of exergy and energy are analyzed at a specific day, 20th June. The assumed power plant in this study is Solar Electric Generating Station VI (SEGS VI), located in California's Mojave Desert. A parametric study, under different working conditions, including different working pressures, temperatures, collector output temperature, steam flow rate, and heat transfer fluid (HTF) flow rate is studied and the effect of variation of parameters on the performance of the plant is investigated. Authors found that, the maximum exergy loss happens in the collector and the maximum energy loss occurs in the condenser. Energy analysis shows that 47% of the total loss energy in the cycle happens in the condenser, as the main component that wastes energy. From exergy analysis, the collector and then boiler are the main components wasting exergy where 68.32% of total exergy loss occurs in these two components in hybrid mode (solar‐fossil fuel). Exergy and Energy efficiency variations throughout the day show that minimum exergy efficiency (32.7%) and maximum energy efficiency (23%) occurs at 12 am. Exergy efficiency variation versus turbine inlet pressure shows that the maximum exergy efficiency (26%) accure at 95 bar. The changes of the absorbed heat and solar irradiation of the 20th of June shows a good agreement with the measured data in validated reference.

Thermodynamic assessment of photovoltaic systems

Energy–exergy analysis and optimisation of a model sugar factory in Turkey

The energy assessment must be made through the energy quantity as well as the quality. But the usual energy analysisevaluates the energy generally on its quantity only. However, the exergy analysis assesses the energy on quantity as well asthe quality. The aim of the exergy analysis is to identify the magnitudes and the locations of real energy losses, in order toimprove the existing systems, processes or components. The present paper deals with an exergy analysis performed on anoperating 50MWe unit of lignite fired steam power plant at Thermal Power Station-I, Neyveli Lignite Corporation Limited,Neyveli, Tamil Nadu, India. The exergy losses occurred in the various subsystems of the plant and their components havebeen calculated using the mass, energy and exergy balance equations. The distribution of the exergy losses in several plantcomponents during the real time plant running conditions has been assessed to locate the process irreversibility. The Firstlaw efficiency (energy efficiency) and the Second law efficiency (exergy efficiency) of the plant have also been calculated.The comparison between the energy losses and the exergy losses of the individual components of the plant shows that themaximum energy losses of 39% occur in the condenser, whereas the maximum exergy losses of 42.73% occur in the combustor.The real losses of energy which has a scope for the improvement are given as maximum exergy losses that occurredin the combustor.

HighlightsFluidized bed drying of rough riceat 40°C with or without ambient air dehumidification worked best based on the energy and exergy utilization.The dryer lost exergy in the exit air, which was the primary cause of thermal inefficiency; recirculation of the exit air could improve the exergy efficiency.Ambient air dehumidification did not reduce the dryer’s energy utilization and exergy efficiency for rough rice.Abstract. Fluidized bed drying of rough rice in the U.S. has not been used to its full potential due to a lack of research to address rice quality impacts and energy consumption. Little research has been done to analyze the energy and exergy of fluidized bed drying of rough rice. Thermal analysis allows using the drying air’s energy better and improving the drying system’s thermal efficiency. In this study, energy utilization and energy utilization ratio were calculated using the first law of thermodynamics, while exergy loss and exergy efficiency were determined using the second law. Drying air temperature (40°C, 45°C, or 50°C), drying bed condition (fluidized or fixed), drying duration (30, 45, or 60 min), and ambient air dehumidification (yes or no) were the tested factors. A lab-scale drying system designed in a previous study was used. Three replicates were performed to minimize any bias or human errors. All factors significantly affected the energy and exergy of the drying process, except dehumidification and replication. The minimum and maximum energy utilization values were 0.01 and 0.55 kJ s-1 for fixed bed drying at 40°C for 30 min with dehumidification and fluidized bed drying at 50°C for 60 min without dehumidification, respectively. The minimum and maximum exergy efficiency values were 13.46% and 49.14% for fixed bed drying at 45°C for 45 min with dehumidification and fluidized bed drying at 40°C for 60 min with dehumidification, respectively. The primary cause of thermal inefficiency was attributed to the energy and exergy losses in the exit air, while the secondary source was the exergy and energy losses from the drying chamber and inlet air pipes. Costly solutions could be recirculation of the exit air and better insulation of the drying chamber and inlet pipes. However, using the optimal drying conditions for the energy and exergy utilization of the drying air is suggested. This study found that fluidized bed drying was better than fixed bed drying overall. At the primary drying stage, fluidized bed drying had a higher exergy efficiency, energy utilization, and energy utilization ratio than fixed bed drying. At 40°C, fluidized bed drying with or without ambient air dehumidification worked best based on the energy and exergy utilization of the drying system. Keywords: Dehumidification, Energy, Exergy, Fixed bed, Fluidized bed, Rice drying.

Energy and exergy analyses were carried out for a pilot parabolic solar dish-Stirling System. The system was set up at a site at Kerman City, located in a sunny desert area of Iran. Variations in energy and exergy efficiency were considered during the daytime hours of the average day of each month in a year. A maximum collector energy efficiency and total energy efficiency of 54% and 12.2%, respectively, were predicted in July, while during the period between November and February the efficiency values were extremely low. The maximum collector exergy efficiency was 41.5% in July, while the maximum total exergy efficiency reached 13.2%. The values of energy losses as a percentage of the total losses of the main parts of the system were also reported. Results showed that the major energy and exergy losses occurred in the receiver. The second biggest portion of energy losses occurred in the Stirling engine, while the portion of exergy loss in the concentrator was higher compared to the Stirling engine. Finally, the performance of the Kerman pilot was compared to that of the EuroDish project.

The study targeted towards drying of cantaloupe slices with various thicknesses in a microwave dryer. The experiments were carried out at three microwave powers of 180, 360, and 540 W and three thicknesses of 2, 4, and 6 mm for cantaloupe drying, and the weight variations were determined. Artificial neural networks (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) were exploited to investigate energy and exergy indices of cantaloupe drying using various afore-mentioned input parameters. The results indicated that a rise in microwave power and a decline in sample thickness can significantly decrease the specific energy consumption (SEC), energy loss, exergy loss, and improvement potential (probability level of 5%). The mean SEC, energy efficiency, energy loss, thermal efficiency, dryer efficiency, exergy efficiency, exergy loss, improvement potential, and sustainability index ranged in 10.48–25.92 MJ/kg water, 16.11–47.24%, 2.65–11.24 MJ/kg water, 7.02–36.46%, 12.36–42.70%, 11.25–38.89%, 3–12.2 MJ/kg water, 1.88–10.83 MJ/kg water, and 1.12–1.63, respectively. Based on the results, the use of higher microwave powers for drying thinner samples can improve the thermodynamic performance of the process. The ANFIS model offers a more accurate forecast of energy and exergy indices of cantaloupe drying compare to ANN model.

Exergy Analysis as a Developed Concept of Energy Efficiency Optimized Processes: The Case of Thermal Spray Processes

This paper deals with the exergy analysis and energy analysis of hybrid solar photovoltaic/thermal (PV/T) collector in the composite climate zone in central India. Experiment was conducted in the month of June. In the energy analysis, the following parameters are calculated: energy loss, energy efficiency, and maximum electrical power output. Various heat transfer coefficients (HTC) such as the radiative heat transfer, convective heat transfer, and overall heat transfer are also determined. In the exergy analysis section, the following parameters are being calculated: exergy loss, exergy efficiency, thermal exergy, and electrical exergy. The error analysis is also calculated. The result obtained from the computation is being validated with previously published results.

Energy and exergy utilization efficiencies in the Japanese residential/commercial sectors