Energy analysis and multi-objective optimization of a novel exhaust air heat recovery system consisting of an air-based building integrated photovoltaic/thermal system and a thermal wheel
This paper presents a feasibility investigation of integrating an air-based photovoltaic/thermal (PV/T) system with a thermal wheel (TW) system for residential applications. The innovative system is capable of pre-heating/pre-cooling the ambient fresh air in winter/summer as well as producing electricity. The performance of the system is numerically evaluated and compared with the conventional building integrated PV/T (BIPV/T) and TW systems. Then, a multi-objective optimization approach is utilized to find the optimum values of geometric and operating parameters in order to maximize the annual average effectiveness of the TW and the first-law efficiency of the BIPV/T collector. The performances of the optimized and un-optimized BIPV/T-TW systems are compared for a complete year. The results demonstrated that the BIPV/T-TW system has a better thermal performance compared with the BIPV/T and TW systems …
Thermoeconomic modeling and multi-objective evolutionary-based optimization of a modified transcritical CO2 refrigeration cycle
In this study, thermoeconomic optimization is applied to a modified transcritical (CO 2) refrigeration cycle. Modified cycle includes an extraction of saturated vapor as a coolant stream from the separator feed to the intercooler. In order to perform multi criteria optimization two objective functions consist of cooling capacity and annual cost rate are chosen. Gas cooler temperature (T gc), gas cooler pressure (P gc), extraction mass flow rate (α) and evaporator temperature (T ev) are selected as decision variables based on parametric study. The thermodynamic and economic modeling of the system is performed. To determine analytical, objective functions GMDH (group method of data handling) neural network method is used and finally with a developed code in Matlab optimal values of decision variables have been obtained. In addition, to better understanding the change of decision variables in optimum point, the …
Scenario-based multi-objective optimization of an air-based building-integrated photovoltaic/thermal system
In this paper, a genetic algorithm-based multi-objective optimization of a building-integrated photovoltaic/thermal (BIPV/T) system is carried out to find the best system configurations which lead to maximum energetic and exergetic performances for Kermanshah, Iran climatic condition. In the proposed BIPV/T system, the cooling potential of ventilation and exhaust airs are used in buildings for cooling the PV panels and also heating the ventilation air by heat rejection of PV panels. Four scenarios with various criteria in the form of system efficiencies and useful outputs are considered to reflect all possible useful outputs in the optimization procedure. This study models a glazed BIPV/T system with various collector areas () and different length to width ratio () to determine the optimum air mass flow rate, bottom heat loss coefficient, depth of the channel as well as the optimum depth …
Experimental energy and exergy analysis of a flat plate solar water heater (SWH) to find optimum collector mass flow rate
This paper presents the experimental study of a flat plate solar collector to find the optimum flow rate of collector with variation of daily solar radiation intensity. The procedure of ASHRAE standard was used for testing the thermal performance of flat-plate solar collector. Results show that using optimal collector flow rate can improve energy and exergy efficiency of SWH. Furthermore, results show that in no load on storage tank overall energy efficiency can improve between 0.25 % and 7 %. In addition, calculations show an increment between 0.18 % and 1.12% for overall exergy efficiency. In the 36 L/h, and 52 L/h and 72 L/h thermal load on storage tank overall energy and exergy efficiency show a reasonable increment with using optimum flow rate of collector. Finally, these experimental analysis results can be a base for design a collector flow rate controller to have a more efficient SWH.
Energy and exergy analysis and multi-objective optimization of an air based building integrated photovoltaic/thermal (BIPV/T) system
The objective of the present work is to investigate the improvement in the energetic and the exergetic performances of glazed and unglazed building integrated photovoltaic/thermal (BIPV/T) systems with the help of multi-objective optimization based on Genetic Algorithm (GA) for Kermanshah, Iran climatic condition. In the proposed BIPV/T system, the cooling potential of ventilation and exhaust airs is used for cooling the photovoltaic (PV) panels and also heating the ventilation air by heat rejection of PV panels. The performance evaluation criteria comprise the first and second law efficiencies. Initially, a multi-objective optimization approach is used to find the optimum values of the geometric parameters and air mass flow rate which maximize the annual average first and second law efficiencies. In the second step, the performances of the optimized and un-optimized BIPV/T systems are evaluated and compared for a …
Exergoeconomic analysis and multi objective optimization of a solar based integrated energy system for hydrogen production
In the current study, an integrated renewable based energy system consisting of a solar flat plate collector is employed to generate electricity while providing cooling load and hydrogen. A parametric study is carried out in order to determine the main design parameters and their effects on the objective functions of the system. The outlet temperature of generator, inlet temperature to organic Rankine cycle turbine, solar irradiation intensity (I), collector mass flow rate (m˙ c o l) and flat plate collector area (A P) are considered as five decision variables. The results of parametric study show that the variation of collector mass flow rate between 3 kg/s and 8 kg/s has different effects on exergy efficiency and total cost rate of the system. In addition, the result shows that increment of inlet temperature to the ORC evaporator has a negative effect on cooling capacity of the system. It can lead to a decrease the cooling capacity from …
Micro-Aeolic in Residential Districts: A Case Study in Sant’Arsenio (South-western Italy)
Renewable energies are sources of energy derived from inexhaustible natural resources. In other words, they are regenerated at the same speed at which they are consumed, and they are freely available. In the new millennium, we find multiple typologies of renewable energies, such as the sun and wind. The latter has undergone tremendous development and evolution owing both to economic and financial incentives and the increased concern with environmental protection. Initially, the integration of wind power into daily life was very difficult because the first power plants were very large, which caused great anxiety around the world – the so-called Not In My Back Yard (NIMBY) problem. For this reason the idea of a wind plant evolved into a softer idea which has brought both change in daily life and the respect for morphology, urbanism and city architecture. In Europe, wind energy has increased in use and …
Multi-objective Optimization of a Two-Stage Micro-turbine for Combined Heat and Power Production
In recent years, reducing the cost of energy production and transmitting electricity in remote areas of the distribution network have attracted many researchers’ attention. One of the methods to fulfill these objectives is using a gas micro-turbine cycle. In this paper, a two-stage micro-turbine with an intercooler was used to produce electricity and heat simultaneously. In this system, the impacts of the effective input parameters, such as compressor pressure ratio, bypass ratio, and re-cooperator yield on cycle performance were studied given that the values obtained from cycle modeling were not continuous, and using GMDH-type neural system (as one of the most widely used neural networks with high potential to model complex data), the desired objective functions were estimated and then simultaneous optimization of the objective functions were implemented. It was shown that the maximum electrical exergy …
Exergoeconomic multi-objective optimization of an externally fired gas turbine integrated with a biomass gasifier
This study deals with thermodynamic and economic analysis of a combined gas turbine and Organic Rankine Cycle integrated with a biomass gasifier. A modified model is used to increase the precision of the gasifier thermodynamic model. Seven decision variables, namely, biomass gasification temperature (Tgasif), combustion temperature (Tcomb), gas turbine inlet temperature (T3), gas turbine isentropic efficiency (ηGT), compressor isentropic efficiency (ηcomp), compressor pressure ration (rp) and maximum ORC operating pressure (P3R), are selected as the main decision variables of the combined system. The total cost rate and exergy efficiency of the system are chosen as the two main objective functions. A group method of data handling (GMDH) type neural network and evolutionary algorithm (EAs) are used for modeling the effects of the seven decision variables on both objective functions. The result of …
Design and Optimization of an Integrated System to Recover Energy from a Gas Pressure Reduction Station
This chapter deals with thermodynamic modeling, parametric analysis, and optimization of an integrated system to recover energy from pressure reduction station in city gate station (CGS). This chapter aims to fully cover the thermodynamic modeling of an integrated system consisting of a turbo expander, an organic Rankine cycle (ORC) and a proton exchange membrane (PEM) electrolyzer to produce and store hydrogen. The pressure of natural gas in transmission pipeline in Iran gas system is high which sometimes go beyond 7 MPa. This pressure needs to be reduced near the cities pipeline pressure to 1.7 MPa. This pressure reduction results in ample potential to recover energy to generate electricity. In the proposed integrated system in this chapter, a comprehensive parametric analysis including the effect of main parameters such as natural gas preheat temperature, the natural gas pressure inlet to …