Exergy

Cooling sector is dominating by vapor compression cooling sector which uses refrigerant which are harmful to environment. The solar ejector cooling system is alternative for vapor compression cycle which uses solar energy to give heat to the generator, which is a viable method for heat generation. The solar ejector cooling system not only fulfills cooling requirement but also helps in energy conservation and protection of environment. It reduces the generator work and decrease the throttling losses. Maintenance requirement and cost is low for ejector cooling system .In this paper, theoretically study is done on enhancement of the performance of solar ejector cooling system. Various system configuration are presented with detailed design. This system still needed a lot of research work to make it alternative for vapor compression cycle based cooling system completely.

In this study, a thermodynamic analysis of an industrial cabinet designed for industrial cabinet systems used in the food industry and providing simultaneous heating and cooling has been made. During the study, energy and exergy analyzes were carried out by using the engineering equation solver program to thermodynamic analysis of seven different refrigerants in the system designed by determining the mass-flow rate to obtain 10 kW heating power, which was selected by using the coolselector two program by using the refrigerant temperature values and operating pressure values. The condenser dew point temperature was kept at +30?C and the evaporator dew point temperature was kept at -1?C. Calculations were made under atmospheric conditions by keeping subcooling at -2?C, superheating at +5?C, and ambient temperature at 20?C. The coefficients determining the system performance were obtained for the highest R22 refrigerant and the lowest for R513A refrigerant. The exergy heating efficienc...

Multi-effect distillation with thermal vapor compression (MED-TVC) is a highly energy-efficient desalination technology that can provide a reliable and sustainable source of high-quality water, particularly in areas with limited energy infrastructure and water resources. In this study, a numerical model based on exergoeconomic approach is developed to analyze the economic performance of a MED-TVC system for seawater desalination. A parallel/cross feed configuration is considered because of its high energy efficiency. In addition, a parametric study is performed to evaluate the effects of some operational parameters on the total water price, such as the top brine temperature, seawater temperature, motive steam flow rate, and number of effects. The obtained results indicate that the total water price is in the range of 1.73 USD/m3 for a distilled water production of 55.20 kg/s. Furthermore, the exergy destructions in the effects account for 45.8% of the total exergy destruction. The M...

Air gap membrane distillation (AGMD) is a widely utilized technology for producing drinking water due to its low heat loss, high thermal efficiency, and compatibility with solar energy. The application of the first and second laws of thermodynamics in energy and exergy analyses provides a comprehensive evaluation of the efficiency of thermal processes. This study aims to examine numerically the energy and exergy performance indicators of a solar AGMD system used for seawater desalination. The simulation was carried out using MATLAB 9.7 software. The total thermal efficiency and overall efficiency of each element in the AGMD system were calculated for various solar field energy outputs, and moreover, a parametric study was conducted. The results indicate that the exergetic efficiency of the AGMD system components was the lowest in the solar field, with the concentrator having the lowest energy efficiency. Additionally, the thermal and exergetic efficiency of the entire solar AGMD sys...

Pyrolysis of non-fossil fuels is raising a growing interest in the nowadays scenario for the alternative supply of energy, fuels and chemicals. Biomass is among the most widely available and technologically promising candidate feedstocks. For simulation purposes and process design goals, kinetic-based models promise to be quite accurate in literature; however, they are computationally intensive and, more importantly, applicable only when kinetic data are available for the specific feedstock and pyrolysis equipment. Here, a different modeling approach is followed by considering that the pyrolysis reactor is under the thermodynamic equilibrium; then, the authors take advantage of the capabilities provided by the Aspen Plus® software. Therefore, this work is focused on the development of an inputoutput reactor model to simulate pyrolysis of a lignocellulosic biomass and to predict the effects of the main process variables. The trends of the predicted results as a function of the proces...

Most solar cookers usually perform a single task of solely cooking food during sunshine hours. Solar cookers coupled with thermal energy storage (TES) material for off-sunshine cooking are usually expensive and require complex engineering designs, and cannot be used for dual purposes, for example, solar water heating and cooking. In this paper, a solar cooker that can perform dual tasks of cooking as well as storing thermal energy to be used during off-sunshine periods is presented. The experimental setup is composed of a parabolic dish, a solar receiver coupled with a flat plate and an oil-circulating copper coil for charging and discharging a storage tank. The objective of the experiment is to evaluate the energy and exergy thermal performance parameters of the dual-purpose system during charging and discharging cycles. The effect of the flow rate and the mass of the load are investigated while using sunflower oil as both the heat transfer fluid and the storage material. Charging ...

Analysis of combined natural convection with surface radiation in a two‐dimensional enclosure is carried out. To search the optimal location of the heat source, the entropy generation minimization approach and conventional heat transfer parameters are used and compared. Air is considered as an incompressible fluid and transparent media filling the enclosure with a steady and laminar regime. The enclosure internal surfaces are also gray, opaque, and diffused. The governing equations are solved using the finite difference approach. The results show that with increase in emissivity, entropy generation decreases, and as the Rayleigh number increases, the rate of entropy generation increases. Furthermore, optimum design with the maximum dimensionless temperature and convective Nusselt number confirms the applicability of the second law for optimal design.

Solar Photovoltaic (PV) systems are degraded in terms of efficiency by increment in their temperature. To keep away from efficiency degradation regarding the temperature increase, various thermal management techniques have been introduced to keep the temperature low. Besides improvement in electrical efficiency, the overall efficiency can be enhanced by using the extracted thermal energy from the cell. The extracted heat in these systems, known as PV/Thermal (PV/T), can be applied for some purposes including water or air heating. This article reviews the works on the PV/T systems exergy analysis and discusses their findings. Based on the findings of the reviewed works, different factors such as the system configuration, used components and elements, and working conditions affect the exergy efficiency of these systems. As an example, use of coolants with improved thermal features, i.e., nanofluids, can cause improvement in the exergy efficiency. In addition to the nanofluid, making u...

Today, the use of alternative fuels that have plant origin has attracted the attention of most countries because these fuels emit less pollution. In this research, bioethanol production has been evaluated considering solar energy sources. In the present study, the possibility of developing net-zero energy concepts in a bioethanol production plant as one of the most consumed energy industries in the field of bio-systems of the country from a technical and economic perspective was investigated. The purpose of this research is to model the bioethanol production plant with the aim of achieving zero net energy using a photovoltaic system. In addition, technical and economic analyses have been used in different approaches for a more detailed investigation. According to the modeling done, in the zero net energy approach, the results showed that the maximum production of electrical energy by the photovoltaic cell is 76.6 GWh/y. For this approach, the return on investment is 10.7 years. The ...

This study focused on exergo–conomic and parametric analysis for Taji station in Baghdad. This station was chosen to reduce the emission of waste gases that pollute the environment, as it is located in a residential area, and to increase the production of electric power, since for a long time, Iraq has been a country that has suffered from a shortage of electricity. The main objective of this work is to integrate the Taji gas turbine’s power plant, which is in Baghdad, with the Rankine cycle and organic Rankine cycle to verify waste heat recovery to produce extra electricity and reduce emissions into the environment. Thermodynamic and exergoeconomic assessment of the combined Brayton cycle–Rankine cycle/Organic Rankin cycle (GSO CC) system, considering the three objective functions of the First- and Second-Law efficiencies and the total cost rates of the system, were applied. According to the findings, 258.2 MW of power is produced from the GSO CC system, whereas 167.3 MW of power i...

Enhancing the sustainability and diversification of Iraq’s electricity system is a strategic objective. Achieving this goal depends critically on increasing the use of renewable energy sources (RESs). The significance of developing solar-powered technologies becomes essential at this point. Iraq, similar to other places with high average direct normal irradiation, is a good location for concentrated solar thermal power (CSP) technology. This study aims to recover the waste heat from the gas turbine cycle (GTC) in the Al-Qayara power plant in Iraq and integrate it with a solar power tower. A thermoeconomic analysis has been done to support the installation of an integrated solar combined cycle (ISCC), which uses concentrated solar tower technology. The results indicate that the examined power plant has a total capacity of 561.5 MW, of which 130.4 MW is due to the waste heat recovery of G.T.s, and 68 MW. is from CSP. Due to the waste heat recovery of GTC, the thermal and exergy effici...

Industrial context of steel processing lines The galvanizing process is used to caot steel (carbon, stainless, silicon) to prevent steel from oxidation Galvanized steel is used for many applications : automotive, industry, buildings, roofs ans wails or even electrical applications Steel is coated in a zinc bath on vertical or horizontal galvanizing lines

For several years cloud computing has been generating considerable debate and interest within IT corporations. Since cloud computing environments provide storage and processing systems that are adaptable, efficient, and straightforward, thereby enabling rapid infrastructure modifications to be made according to constantly varying workloads, organizations of every size and type are migrating to web-based cloud supported solutions. Due to the advantages of the pay-per-use model and scalability factors, current video on demand (VoD) streaming services rely heavily on cloud infrastructures to offer a large variety of multimedia content. Recent well documented failure events in commercial VoD services have demonstrated the fundamental importance of maintaining high availability in cloud computing infrastructures, and hierarchical modeling has proved to be a useful tool for evaluating the availability of complex systems and services. This paper presents an availability model for a video s...

In this paper, energy and exergy analysis is used to show the exergetic performances for an Organic Rankine Cycle (ORC). This system supplies with electrical energy an existing building with a known configuration. The ORC system is supplied with solar energy from an evacuated solar tube collector. The use of solar energy and the ORC system instead of conventional energy sources reduces pollution and offers energy savings. The simulations of the operating for the ORC system have been performed using several working fluids. The optimization procedure based on the exergetic analysis enabled the choice of the best working fluid. The optimization looked for reducing the exergy destruction to the key parts of the system. The careful selection of the working fluid is essential to reduce the exergy destructed and increase the exergy efficiency for the entire installation. Throughout this work, we were able to prove that this proposed configuration of a solar powered Organic Rankine Cycle is...

Poultry brooding requires optimal provision of heat, medication, water and feed on abuilt environment deep litter for dayold chick. This built environment (Trombe wall solar chick brooder) has been developed but has not been numerically modeled and validated. Therefore, numerical modeling, simulation and validation are carried out on Trombe wall solar chick brooder. Predictive linear differential equations based on physical, mathematical principles and relationships governing thermo-physical properties of the components of the brooder are formulated, discretized and expressed in their finite different forms using SCILAB 5.5.2. Predicted data is gotten from the simulation thereafter validated with the measured data. The temperature varied with definite pattern (sinusoidal) for both measured and predicted for the six days simulation with average temperature variation of 3C -5C.T-test statistics is carried out on predicted and measured mean data: temperature of Trombe wall glaze (TG1),...

This article presents exergy cost analysis of a single stage vapor absorption refrigerant system (VARS) with water-LiBr pair whose energy source is waste steam. The aim of Exergy Cost Analysis is to define the cost formation process of products and residues in the operation of energy conversion systems. In the first part of this work, authors have described a thermoeconomic data model to obtain the Fuel-Product table for the above VARS. This model is a fundamental concept of symbolic exergoeconomics. The FP table represents the productive structure which shows, where the product of each component is used and the origin of the resources of each component. In the later part of this article, complete exergy cost analysis is performed by applying FP table as input data. This approach allows one to find the exergy cost of each subsystem of the proposed vapor absorption refrigerant system. Besides, the unit exergy cost of the product is decomposed in the contributions of the irreversibili...

In this paper, a comparative thermodynamic analysis on energy and exergy viewpoint is done on different low global warming potential (GWP) refrigerants to find the possible alternative of high GWP refrigerant R410A. R410A is used nowadays in air conditioning systems due to its ozone-friendly characteristic as zero ozone depletion potential (ODP=0) but it has high GWP (GWP=1924) that leads to global warming. Now a day’s global warming is considered to be one of the critical aspects when environmental protection is taken into consideration and researchers from every corner of the globe are working to find refrigerants that not only have zero ODP but it has low GWP too. In this analysis, four prospect refrigerants namely R32, R447A, R447B, and R452B have been studied to find their suitability to replace R410A on different performance criteria as the coefficient of performance (COP), power consumption, exergy efficiency, and exergy destruction. Thermodynamic properties of the studied re...

This work presents an experimental energy and exergy analysis for the operation of a multi-cylinder four-stroke direct injection turbocharged and intercooled commercial diesel engine. A simplified model of an extended thermodynamic cycle over compressor-intercooler-engine and turbine was adapted, and then being calibrated with engine dynamometric bench measurements. For two representative engine operation modes - rated power and maximum torque - at full load, second law terms were assessed in function of chemical diesel fuel availability. The result was an integrated method for a reliable assessment of availability losses, which becomes a useful tool to evaluate the further improvement of process efficiency and of the energy harvesting potential.

The objective of this study is to perform the energy and exergy analysis of an integrated ground-source heat pump (GSHP) system, along with technical assessment, for geothermal energy production by deployment of Engineering Equation Solver (EES). The system comprises heat pump cycle and ground heat exchanger for extracting geothermal energy from underground mine water. A simultaneous energy and exergy analysis of the system is brought off. These analyses provided persuasive outcomes due to the use of an economic and green source of energy. The energetic coefficient of performance (COP) of the entire system is 2.33 and the exergy efficiency of the system is 28.6%. The exergetic efficiencies of the compressor, ground heat exchanger, evaporator, expansion valve, condenser and fan are computed to be 38%, 42%, 53%, 55%, 60% and 64%, respectively. In the numerical investigation, different alteration such as changing the temperature and pressure of the condenser show promising potential fo...