Energy and economic evaluation and multicriteria optimization of different arrangements of integrated photovoltaic thermal and heat recovery wheel system

The present research deals with the multicriteria optimization of two arrangements of a combined system including a building‐integrated photovoltaic thermal (BIPV/T) with a heat recovery wheel (HRW) for Kermanshah weather condition in Iran. The considered arrangements have two operational approaches including heat and cool approaches. In the heat approach of the arrangement (I), the fresh ambient air is preheated in two steps by flowing first among the HRW and then through the BIPV/T collector. In the cool approach of the arrangement (I), the outdoor air stream enters the HRW and is precooled there by exchanging heat to the building exhaust air. The exhaust air then enters the BIPV/T collector and cools the PV panels, thereby augmenting their efficiency. The cool approach of the arrangement (II) is like the arrangement (I), while in the heat approach of the arrangement (II), the outdoor air first gets into the …

Potential of thermoelectric waste heat recovery in a combined geothermal, fuel cell and organic Rankine flash cycle (thermodynamic and economic evaluation)

The present work aim is performance improvement of an integrated geothermal system by proposing the integration of organic Rankine flash cycle (ORFC) with the Proton exchange membrane fuel cell (PEMFC) and waste heat recovery from condensers using thermoelectric generator (TEG) modules. To achieve this goal, a novel integrated system is proposed, thermodynamically modeled, investigated, and compared with the conventional system. To assess the performance of proposed system, thermodynamic and economic evaluations are performed. The results indicate that R123 as working fluid, has the best performance for the conventional and proposed systems. The findings demonstrate that with employing TEG modules an increase of 2.7% and 2.8%, for the first and second law efficiencies can be obtained respectively. Additionally, the results of parametric analysis indicate that however the geothermal …

Multi-objective optimization of a photovoltaic thermal-compound sensible rotary heat exchanger system using exergo-economic and enviro-economic approaches

This paper presents exergo-economic and enviro-economic assessment of a novel building integrated photovoltaic thermal-compound sensible rotary heat exchanger (BIPVT-SRHX) system. The innovative BIPVT-SRHX system preheats/precools the outdoor air in winter/summer and generates electric power. The performance of the system are analyzed from the energy/exergy viewpoints for Kermanshah, Iran climatic conditions. Then, the multi-objective genetic algorithm (MOGA) optimization is used to optimize to determine the optimum values of geometric and operating parameters in order to maximize the annual average exergo-economic and enviro-economic aspects of the system. The considered geometric and operating parameters include the length, width and depth of the air channel located underneath the PV modules, the air mass flow rate, and the diameter, rotational velocity and length of the SRHX …

3-E analysis and optimization of an organic rankine flash cycle integrated with a PEM fuel cell and geothermal energy

The current research deals with thermodynamic and economic analyses and optimization of a geothermal system integrated with organic Rankine flash cycle (ORFC) and a polymer electrolyte membrane fuel cell (PEM-FC). A thermodynamic model for ORFC and PEM-FC is developed to investigate employing the PEM-FC in a combined geothermal ORFC. A comparative study is carried out to determine the effect of applying PEM-FC in a geothermal based ORFC. The validation of PEM-FC simulation with experimental data from the literature shows a good agreement. The results of numerical modeling indicate that using the rejected heat in the PEM-FC instead of the low-temperature geothermal source can increase the net output power from 254.9 kW to 1628.9 kW and the exergy efficiency from 23.77% to 36.19%, in the case of R123 as working fluid for the ORC system. Furthermore, using the PEM-FC imposes 9 …

Exergy and exergoeconimic analysis and multi-criteria optimisation of 1 MW installed CCHP system (a case study in Kashan University)

The present study deals with exergy and exergo-economic evaluation of a 1 MW combined cooling, heat and power (CCHP) system, composed of a natural gas prime mover internal combustion engine located in the main campus of the University of Kashan, Kashan, Iran. Using appropriate linking between engineering equation solver (EES) and MATLAB software, thermal and economic modelling and multi-criteria optimisation (MCO) have been performed. The optimisation results showed that the minimum total exergy destruction rate occurs for the exhaust gas extraction factor of 0.68, which causes $33.52/h total cost rate. For this case, among all of the system components the highest exergy destruction rate of 1,700 kW belongs to the engine. In addition, the results of the genetic algorithm-based multi-objective optimisation represented that the optimisation causes $2.68/h decrease in total cost rate and reduction of …

Energy and exergy analyses of dual refrigerant system for liquefaction of natural gas

Present study proceeds thermodynamic modelling, and analysis of dual refrigerant system for liquefaction of natural gas (LNG) that is one of the most important technologies in producing LNG. Using energy equations pressure, quality, enthalpy, entropy of natural gas and two refrigerants, i.e., methane and propane are specified. The effects of different cycle variables on the thermodynamic performance especially the coefficient of performance (COP) is studied. Using the second law of thermodynamic for the system components, the exergy destruction rates has been found. The exergy analysis results show that heat exchanger I (HX I), heat exchanger II (HX II) and turbine have the highest exergy destruction rate. Furthermore, results indicate that the total exergy destruction rate of studied cycle for generation of 1 kg/s LNG is 2,996 kW. Moreover, energy and exergy analysis show that important parameters such as …

Solar based CO2 power cycle employing thermoelectric generator and absorption refrigeration: Thermodynamic assessment and multi-objective optimization

A novel integrated power generation and refrigeration system proposed in this paper. The system consists of parabolic trough collectors, supercritical-CO2 based Brayton cycle, an absorption refrigeration cycle, and a thermoelectric generator. Of particular interests of this paper are thermoelectric power generator and performance characteristic of closed Brayton cycle working with CO2. Employing energy and exergy analyses, the effect of integrating thermoelectric module at different points is studied by comparing power generation and efficiency before and after applying the thermoelectric module. Besides, the whole system is analyzed with the use of first and second law thermodynamics to determine energy and exergy efficiencies with exergy destruction rates. Furthermore, a multi-objective optimization method is conducted by defining two scenarios using different types of objective functions to specify the …

Energy, exergy and exergo-environment analyses, and tri-objective optimization of a solar still desalination with different insulations

One of the most substantial aspects of the solar still systems that should be significantly considered is their economic and environment aspects. The present study deals with analyzing and identifying the behaviors of a cascade solar still desalination system in the presence of different insulation types and phase change materials. A Matlab code is developed to solve the energy equations for different components of the system simultaneously using ODE-45 solver. A comprehensive thermal, economic and environment analyses performed on the solar still desalination system with different insulation types and phase change materials. With selecting three objective functions namely total annual cost (T A C), exergy efficiency (η e x), and exergy-based CO 2 mitigation (φ C O 2, e x− b a s e d), the tri-objective optimization is carried out for two considered cases of solar still desalination units. The thermal analysis …

Second law analysis and multi-criteria optimization of turbulent heat transfer in a tube with inserted single and double twisted tape

Present paper deals with numerical modeling of heat transfer in a tube with two types of twisted tape inserted in a circular tube. Single twisted tape and double twisted (coaxial) tape as two enhancing elements are added to the circular tube. A numerical investigation conducted to explore the effects of these elements on the pressure drop (ΔP), convective heat transfer coefficient (h) and entropy generation (S). The results demonstrate that increasing the Reynolds number has a positive effect on the convective heat transfer coefficient in all cases due to enhance the flow swirling which improves the heat transfer on the tube wall. The results represent that the coaxial tape in the lower twisted ratio (TR) has a better performance than single tape while the opposite is true for a high twisted ratio. The results of pressure drop for two studied cases reveal that pressure drop in the coaxial tape is higher than single tape in all …

Thermodynamic and economic analyses and multi-objective optimization of harvesting waste heat from a biomass gasifier integrated system by thermoelectric generator

Thermoelectric waste heat recovery systems (WHRSs) can be used appropriately to recover wasted heat from various industrial processes. In the current work, new thermodynamic modeling was developed to harvesting waste heat from an integrated system includes an externally fired gas turbine and a biomass gasifier by three thermoelectric WHRSs. The biomass system consisted a gas turbine cycle, an organic Rankine cycle (ORC) and a domestic water heater were first thermodynamically modeled, and then effects of adding thermoelectric WHRSs to different locations of the system were investigated. It is observed that first law efficiency of the system (η 1) will become 17.11%(an increase of 0.35%) if the total output heat from the stack enters W H R S s. The efficiencies of the system can be increased from 16.76% to 17.93% by placing a WHRS on the condenser of ORC. Moreover, the operating parameters have …