Increasing the production of energy in line with industry development, transportation, and life quality improvement is an interesting topic needs to be addressed. Energy policymakers and researchers ...have aimed at energy management, particularly by improving energy systems performance. This review paper explains the rising interest of thermoelectric technology and applications. Nowadays, thermoelectric technology such as thermoelectric generators (TEGs) and thermoelectric cooling systems (TECs) provide heat loss recovery of thermodynamic units for power production of remote areas. Unlimited solar energy can also be employed for thermoelectric power production. This paper describes the principles of thermoelectricity and presents an explanation of current and upcoming materials. Developed models and various performed optimization of thermoelectric applications by using non-equilibrium thermodynamics and finite time thermodynamics are discussed as well. Additionally, a number of topical applications and energy resources are introduced. The main goal of this study is to give a clear overview of thermoelectric technology and applications.
•Explains the rising interest of thermoelectric technology and applications.•Describes thermoelectricity principles and current and upcoming materials.•Developed models and various performed optimization are discussed.•Includes non-equilibrium thermodynamics and finite time thermodynamics.•A number of topical applications and energy resources are introduced.
In this research, a biorefinery plant is proposed to generate biofuel through fast pyrolysis and gasification. The proposed biorefinery comprises hydrotreating, hydrocracking, and steam reforming ...sections. The whole plant, each section, and each designed component are analyzed and evaluated based on an exergy-based approach, i.e., exergy, exergoeconomic, and exergoenvironmental analyses. The exergy cost and exergoenvironmental impact of each section and each component are calculated and compared to monitor the economic effect and environmental impact and also to prioritize the section and the component which are not obtained as acceptable values in the analyses. It is revealed that the hydrocracking unit is the most efficient sector in comparison with others with the exergy efficiency of 89.75%. The exergoeconomic analysis illustrates that the used compressor in the hydrotreating unit and pumps in hydrocracking and steam reforming units have the most exergy cost in comparison with other components in the whole process. Similarly, exergoenvironmental assessment declares that employed reactors of the biorefinery plant have the most destructive effect on the environment.
This study is focused on presenting a novel approach for the cogeneration of liquid carbon dioxide (LCO
2
) and liquefied natural gas (LNG). The main idea of this development is to use air for ...storing and producing energy, meanwhile, transferring cold energy for the liquefaction process of natural gas. Therefore, a mixed refrigeration cycle and liquid air cold energy recovery are considered to liquify natural gas. A carbon dioxide liquefaction cycle and a combined cooling and power cycle are also integrated to increase the output performance of the system by taking advantage of carbon dioxide liquefaction and power production. The power production sub-cycle is assisted with solar parabolic trough collectors, which are placed in the city of Bandar-Abbas, Iran. The obtained results demonstrate that the developed system supplies liquefied natural gas and liquid carbon dioxide at 3600.4 and 1188.2 kg h
−1
, respectively. The exergy calculation displays that the heat exchanges (45.14%), compressors (17.24%), and collectors (14.03%) have the most share of exergy destruction compared to other compounds. The exergy efficiency and irreversibility of the proposed integrated system achieve a 48.91% and 1175 kW, respectively. The sensitivity investigation indicates that the specific energy decreases to 813.6 kJ kg
−1
-LNG and exergy efficiency increases up to 48.91% when the pressure in liquid air increases from 20 to 60 bar. The specific energy and exergy efficiency decrease to 799.9 kJ kg
−1
-LNG and 47.76%, respectively with the increase in outlet temperature of the solar collector exchanger from 155 to 175 °C.
Waste heat recovery systems are proposed to be an environmentally benign and a cost-effective application for efficiency improvement of energy conversion systems. In this research, three different ...subsystems—gas turbine cycle, steam Rankine cycle, and a coupled organic Rankine cycle–vapor compression refrigeration—are integrated to obtain a high-efficiency layout from technical, economic, and environmental viewpoints. The whole system is simulated and analyzed with regard to energy, exergy, and exergoeconomic models. Furthermore, a sensitivity analysis is made to enable a better understanding of the effect of design parameters on the final performance of the total system. Based upon a parametric study, R602 demonstrates advantageous features such as higher thermal efficiency and improved exergetic efficiency in the ORC–VCR subsystem. Overall, analyses show that the proposed integrated system obtains the total energy and exergy efficiencies of 46.1% and 40.57%, respectively. Moreover, it has been illustrated that the overall structure is able to provide a 3810 kW net output power and a 303.8 kW cooling load. Besides, exergoeconomic evaluation depicts an exergy cost of 49.84 ($ GJ
−1
) and an exergy cost rate of 826.4 ($ h
−1
).
In the current study, Multilayer Perceptron Artificial Neural Network (MLP‐ANN) mode, Radial Basis Function Artificial Neural Network (RBF‐ANN), and Elman Back Propagation Neural Network (Elamn ...BP‐ANN) are developed to predict the thermal efficiency of a flat‐plate solar collector. TiO2 (20 nm)/water nanofluids are prepared using two‐step method and used in the designed solar system. All experiments are done in Mashhad city, Iran (Longitude/Latitude: 36.2605°N, 59.6168°E), according to EUROPEAN STANDARD EN 12975‐2 as a quasi‐dynamic test (QDT) method, and the solar collector is exposed to the south with the tilt angle of 55°. Three levels of inlet temperature (ambient air temperature, 52 and 74°C), 3 levels of volumetric flow rate (36, 72, and 108 L/(m2.h)), and 4 levels of nanofluid concentrations (0, 0.1, 0.2, and 0.3 wt.%) are considered as the input data, and the thermal efficiency of the solar system is calculated. According to the output results of developed models, the best prediction of thermal performance is obtained by MLP‐ANN model, although other generated models are also able to predict the efficiency of the solar collector with appropriated accuracy.
Application of TiO2/water nanofluid in flat‐plate solar collector. The maximum obtained thermal efficiency is around 55.76%. Machine‐learning methods to predict the thermal efficiency of solar system. MLP, Elman, and RBF methods are suitable ways to predict the performance of system. Best prediction of thermal performance was obtained by MLP‐ANN model.
The energy efficiency (EnE) and exergy efficiency (ExE) investigations of passive and active inclined solar still (PISS and AISS) are presented in this work. The PISS produced maximum EnE and ExE of ...40.21 and 2.88% and the AISS produced maximum EnE and ExE of 48.38 and 6.71%, respectively. The distilled water production, EnE, ExE of the AISS is 47, 16.89, and 57.08% higher than that of the PISS. The daily power generation from the photovoltaic (PV) panel in the PISS is 69 W, and that in the AISS is 52 W. The daily electrical efficiency of the PV panel in the PISS is 9.17%, while that in the AISS is 7.20%. Moreover, the daily average overall EnE, daily average overall ExE, and economic analysis of the PISS and the AISS are calculated. The daily overall EnE and ExE of the system are higher in the case of AISS in comparison to the PISS. The overall daily EnE and ExE of the AISS are 5.24 and 29.63% higher as compared to the PISS. Also, the cost of yield production is noted to be cheaper in AISS (0.018 $/L) when compared to the PISS (0.029 $/L).
In this study, machine learning methods of artificial neural networks (ANNs), least squares support vector machines (LSSVM), and neuro-fuzzy are used for advancing prediction models for thermal ...performance of a photovoltaic-thermal solar collector (PV/T). In the proposed models, the inlet temperature, flow rate, heat, solar radiation, and the sun heat have been considered as the input variables. Data set has been extracted through experimental measurements from a novel solar collector system. Different analyses are performed to examine the credibility of the introduced models and evaluate their performances. The proposed LSSVM model outperformed the ANFIS and ANNs models. LSSVM model is reported suitable when the laboratory measurements are costly and time-consuming, or achieving such values requires sophisticated interpretations.
The main aim of this study is to evaluate thermal performance and exergy analysis of a shell-and-tube heat exchanger with a new technique called air bubble injection. The study has been carried out ...with different parameters such as flow rate, fluid inlet temperature, and different air injection techniques. The air has been injected at different locations such as the inlet of pipe, throughout the pipe, and in the outer pipe of the heat exchanger. Based on the results, the performance of the heat exchanger enhances with an increase in the flow rate and the fluid inlet temperature. The exergy loss and dimensionless exergy loss increase with a rise in the flow rate. The maximum and dimensionless exergy losses are obtained at a maximum flow rate of 3.5 l min
−1
. With the air bubble injection in the heat exchanger, it has been observed that the temperature difference increases, which leads to an increase in the exergy loss. The injecting air bubbles throughout the tube section shows that minimum dimensionless exergy is 27.49% concerning no air injection.
In this research, a novel liquefied natural gas (LNG) reproduction process is developed to re-liquefy generated boil-off gas from the LNG tank through an ejector refrigeration unit driven by an ...organic Rankine cycle, an auto-cascade refrigeration, and an ethylene compression refrigeration cycle. The developed system is evaluated through exergy efficiency, exergy destruction, coefficient of performance, and specific energy consumption indexes. Exergy destruction evaluation shows that heat exchangers and compressors are the most destructive equipment in the developed layout. The presented cycle obtains an exergy efficiency of 0.5936. It has been shown that increasing the adiabatic efficiency of the compressor leads to increasing the coefficient of performance while it decreases the required specific energy consumption. In addition, it has been monitored that increasing the boil-off gas re-liquefaction pressure yields an increase in the specific energy consumption. Besides, it has been illustrated that turbine inlet temperature is a crucial factor in the performance of the system, and achieving higher temperature has a positive factor on the whole system.
Thermal performance of pulsating heat pipes (PHPs) is dependent to several factors. Inner and outer diameter of tube, filling ratio, thermal conductivity, heat input, inclination angle, and length of ...each section are the most influential factors in the design process of PHPs. Since water is a conventional working fluid for PHPs, thermal resistance and effective thermal conductivity of PHPs filled with water are modeled by applying a GMDH (group method of data handling) neural network. The input data of the GMDH model are collected from other experimental investigations to predict the physical properties including thermal resistance and effective thermal conductivity of PHPs filled with water as working fluid. The accuracy of the introduced models are examined through the R
2
tests and resulted in 0.9779 and 0.9906 for thermal resistance and effective thermal conductivity, respectively.
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