Energetic Performance Analysis Research Articles

A Hybrid Energy System Based on Externally Fired Micro Gas Turbines, Waste Heat Recovery and Gasification Systems: An Energetic and Exergetic Performance Analysis

The opportunities related to the adoption of synthetic gaseous fuels derived from solid biomass are limited by the issues caused by the peculiarities of the syngas. The aim of this paper is to analyze several possible layouts of hybrid energy systems, in which the main thermal source is the organic fraction of municipal solid wastes. The case of a small community of about 1000 persons is analyzed in this paper. The examined layouts coupled an externally fired micro gas turbine with a waste heat recovery system based on both an Organic Rankine Cycle and supercritical CO2 gas turbines. A thermodynamic analysis has been carried out through the use of the commercial software Thermoflex 31, considering the losses of each component and the non-ideal behavior of the fluids. The results of the numerical analysis highlight that the introduction of a waste heat recovery system leads to an increase of at least 16% in the available net power, while a cascade hybrid energy grid can lead to a power enhancement of about 29%, with a considerable increase also in the energetic and exergetic global efficiencies.

Energetic and Exergetic Performance Analysis of a Double Pass Asymmetric CPC Photovoltaic/Thermal Solar Collector Suitable for Building Facade

Energetic and Exergetic Performance Analysis of a Double Pass Asymmetric CPC Photovoltaic/Thermal Solar Collector Suitable for Building Facade

Energetic and exergetic performance analysis of a double pass asymmetric CPC photovoltaic/thermal solar collector suitable for building facade

Energetic and exergetic performance analysis of a double pass asymmetric CPC photovoltaic/thermal solar collector suitable for building facade

Energetic, Economic and Environmental Performance Analysis of a Micro-Combined Cooling, Heating and Power (CCHP) System Based on Biomass Gasification

In this paper, the performance of an innovative micro-combined cooling, heating, and power (CCHP) system, based on an internal combustion engine fueled with syngas from woody biomass, is analyzed. In particular, a numerical model, which considers a direct coupling between the internal combustion engine and the gasifier as a novel aspect, was developed, validated and applied to three different case studies to perform an energetic, economic and environmental analysis. For each considered case, the CCHP system was equipped with a reversible electric air–water pump and a back-up boiler. The energy analysis shows that the user characterized by a high uniformity of the thermal load exploits the CCHP system in the optimal way as it allows for the highest thermal self-consumption rate. On the contrary, for the cases in which the thermal request is not uniform, a high electric surplus is recorded. In this case, the adoption of the heat pump allows to compensate for this disadvantage by recovering the electric surplus, thus achieving a thermal integration and CO2 emissions reduction of about 15.8% with respect to the case in which no heat pump is used. Overall, the results demonstrate the affordability of the biomass-based CCHP system, which is of increasing importance in this period of contingent international political crisis.

Energetic and exergetic performance analysis of finned plate solar air heater integrated with PCM-aluminium chips composite as heat storage system

ABSTRACT In this experimental work, the effect of combining a finned absorber solar air heater (FSAH) with PCM-aluminum chips composite on enhancing its thermal response is experimentally investigated based on energy and exergy standpoints. Experiments are conducted to compare the thermal response of FSAH using PCM-aluminum chips composite against the FSAH with no PCM and with PCM only, under weather circumstances in Baghdad city, Iraq. The thermal response factors of the proposed FSAH are examined for varying air mass flow rates, such as 0.009, 0.029, and 0.061 kg/s, and constant PCM’s mass. The results reveal that against the FSAH with no PCM, the energy heat gain of FSAH with PCM is only increased by 65.1% and its energy and exergy efficiencies are increased by 55% and 12%. Meanwhile, the inclusion of an aluminum chips within the PCM is found to be the best configuration among all the tested cases, providing an outlet air temperature for a long duration time of about 2.25 hr compared to FSAH with no PCM. In addition, the energy heat gain is increased by 115.4% and its energy and exergy efficiencies are increased by 168% and 123%, respectively, which is suitable for agricultural drying and space heating operations.

Performance enhancement and parametric optimization of a sky radiative and thermoelectric hybrid cooling system for water harvesting from humid air

The aim of this study is to deepen into the study and analysis of energetic performance of a novel RSC-TEC hybrid cooling system for water harvesting by combining thermoelectric and radiative sky cooling mechanisms. The main contents of this study are to propose the thermodynamic model of the novel hybrid system considering main losses and steady-state assumption, solve the operating temperatures of the thermoelectric cooler by energy balance equations, discuss the influences of multiple system variables including air flow rate, electric current of the thermoelectric cooler, ambient relative humidity, and ambient temperature on effectiveness and water production rate, and, evaluate and compare the performances of the whole system and the thermoelectric cooler. The main novelties are to provide the parametric optimum selection criteria of some key parameters of the overall system operating at optimum states. Results show that the maximum effectiveness and water production rate of the hybrid system can reach 1.93×10- 6 kg J−1 (amount to 6.95×103 ml of water by consuming 1 kWh of electrical energy) and 1.51×10- 5 kg s−1 (amount to 54.4 ml of water within 1 h) at 0.75 relative humidity and the ambient temperature of 298 K. In addition, the system is capable of producing about 140 ml of water within 1 h from the air with high relative humidity, which is more efficient than other different existing air water generators. The optimized effectiveness (coefficient of performance) of the hybrid system is much better than that of a separate (subsystem) thermoelectric cooler operating at the same ambient condition. The results obtained reveal the advantages of the present hybrid system. Complementary perspectives on compromise performance regimes are also displayed from Pareto front yielded from numerical multi-parametric and multi-objective methods.

A two-stage sodium converter coupled to a two-stage TEG: Parametric optimization

The aim of this study is to deeply study and analysis of energetic performance of the novel coupled system composed of a two-stage sodium thermal electrochemical converter and a two-stage thermoelectric generator. The main methods are to establish the model of the coupling system by considering the main irreversibilities, and obtain the analytical expressions of the power outputs and efficiencies of two subsystems and coupling system. The main novelties are to obtain the optimum ranges of critical parameters of the coupled system and give the reasonably matching conditions between the subsystems. The main contents of this study include that the influences of the intermediate and condenser temperatures of the sodium thermal electrochemical converter and current density of the first stage sodium thermal electrochemical converter as well as the electric current of the two-stage thermoelectric generator on the efficiency and power output density are discussed and the maximum power output density and efficiency of the system are calculated and compared with those of the single two-stage sodium thermal electrochemical converter and the existing coupling models. Results show that the maximum efficiency and maximum power output density of the coupled system attain 0.413 and 68.7×103 W m−2 and exhibit an improvement of about 14.1% and 66.7% than those of the standalone two-stage sodium thermal electrochemical converter respectively, and the maximum efficiency of the whole system increase 37.7% compared with that of the existing coupling system. The results obtained indicate that the performance of the proposed system is greatly improved by efficient the exhaust heat utilization. In addition, the multi-objective and multi-parametric optimization analyses are adopted to search for the global optimization profile and validate the obtained findings.

A Comprehensive Comparative Analysis of Energetic and Exergetic Performance of Different Solar-Based Organic Rankine Cycles

In this work, a comprehensive energetic and exergetic comparative assessment is presented for the simple solar organic Rankine cycle (SORC), regenerative solar organic Rankine cycle (RORC), and dual-loop solar organic Rankine cycle (DORC), considering parameters such as the net power produced, exergy destruction, exergy, and energy efficiency in four zones located in Colombia due to their high solar irradiation potential. The energetic and exergetic balances were applied for each system component, using toluene as the working fluid. The RORC system showed a 2% increase in efficiency over the SORC, while the DORC cycle was lower than the SORC (45.85%) and RORC (46.90%) systems. Finally, for the exergy analysis, the results revealed that the SORC (5.3%) and RORC (5.2%) systems had the highest efficiency compared to DORC systems. Additionally, the highest exergy destruction (89%) was related to the collector, followed by the evaporators (1–2%), pumps (0.1%), and turbines (1.12%).

Combined Energetic and Exergetic Performance Analysis of Air Bubbles Injection into a Plate Heat Exchanger: An Experimental Study

This paper aims to give a comprehensive energetic-exergetic performance analysis on the impacts of injecting-submillimeter of air bubbles into both sides of cold and hot water streams before the entrance port of a corrugated plate heat exchanger (C-PHE) having ten plates within counterflow configuration. Hence, optimize the energy and exergy effectiveness at different operating conditions for counter and parallel fluid flow configurations. Hot streams were studied in seven flow rates ranging from 280 L/h to 880 L/h with a regular step of 100 L/h, and constant hot water temperature and cold-water stream of 50 °C and 290 L/h, respectively. Hence, the air was discharged with four flow rates ranging between 150 and 840 L/h. The obtained results showed the vital role of the ABI technique in enhancing the NTU and effectiveness by 59% and 18.6%, respectively, for CWS. The entropy generation was reduced to 0.038 W/K and the augmentation entropy generation number to 0.087 at the low airflow rate for CWS, which are the main parameters for evaluating the EGM. These two parameters increase the Witte-Shamsundar-efficiency to a maximum value of 98.6% at the same operating conditions. Moreover, the exergy effectiveness was enhanced to a maximum value of 80.9% at a high ABI flow rate and low volumetric rate of the hot stream at CWS. The thermo-economic assessment has been carried out, which revelers the positive effects of ABI on the combined energetic and exergetic performance on both sides, i.e., hot and cold sides.

Endoreversible Performance Analysis of a modified dual cycle and comparison with the classical engine cycles

In this study, energetic performance analysis of an endoreversible modified dual cycle is performed. In this context, the net work and thermal efficiency of the modified cycle, are formulated with respect to certain basic design parameters. Also, conditions for maximum net work are investigated, and for the modified and classical cycles, compression ratio that maximizes the net work are analytically obtained with respect to extreme temperature ratio, isothermal expansion ratio, and cutoff ratio. The results of the performance analysis of the modified dual cycle are compared with those of classical engine cycles (otto, diesel and dual cycles). In terms of net work or power, modified cycle is demonstrated to be considerably more advantegous than the classical cycles. In terms of thermal efficiency, modified cycle performs better than dual and diesel cycle, but falls short slightly of the otto cycle.

Energetic and exegetic performance analysis of flat plate solar collector under variables heat transfer coefficient and inlet water temperature

Present work involves a theoretical energetic and exegetic analysis on the thermal efficiency of the flat plate solar system under variables water inlet temperature and heat loss coefficient. The experimental analysis has been performed based on experimental data that conducted under outdoor conditions of Duhok city at north of Iraq in May 2019. The operating conditions and solar irradiance on the energetic and exegetic efficiencies of the system have been tested. The results displayed that the climatic conditions have significant effect on the energetic and exegetic performance outputs. The solutions also display that the mass flowrate has a proportional relation with energy and exergy performances. Furthermore, the results show that the water inlet temperature has an inverse relationship energy efficiency and a proportional relationship with exergy efficiency. The energy efficiency has been increased with increasing the solar irradiance, whereas the exergy efficiency has been decreased with rising the solar irradiance. The maximum energetic and exegetic performances have been found equal 70% and 4% respectively.

Carbon nanotubes/activated carbon hybrid as a high-performance suspension electrode for the electrochemical desalination of wastewater

In this study, we employed carbon nanotubes (CNTs) to improve the performance of flow-electrode capacitive deionization (FCDI) for wastewater desalination in isolated closed-cycle (ICC) mode. The effects of CNTs loading and initial salt concentration on FCDI desalination were evaluated with energetic performance analysis. FCDI was carried out for the desalination with real wastewater for technology demonstration. The addition of CNTs significantly improved the average salt removal rate (ASRR), associated with a decrease in the flow-electrode flowability. FCDI with 0.25 wt% CNTs had an ASRR of 1.59 μmol/cm2–min, which was 1.7-fold higher than that without CNTs. This was attributed to the bridging effect of CNTs for more rapid charge transfer. Increasing the initial salt concentration from 0.05 to 0.30 M led to a higher ASRR, resulting from a reduction in the electrical resistance in the cell. After further increasing the salt concentration to 0.50 M, the charge efficiency was relatively decreased due to co-ion leakage. Notably, FCDI for the desalination of real saline wastewater achieved a high decrease in conductivity (94%), a high charge efficiency (>99%), and low energy consumption (0.034 kWh/mol). Our results demonstrated that adding CNTs is a feasible approach to achieve high-performance FCDI for sustainable wastewater desalination.

An Assessment of Energetic and Exergetic Performance Analysis of Central Heating Plant in a University Campus

Central heating and cooling plants are used in all living areas. Therefore, efficient use of energy is important. Energy and exergy analysis of the central heating plant located on the university campuswas performed and the performance was evaluated. Energy and exergy analysis of the hot steam boiler and other sub-systems connected to the heating plant was performed and the results were calculated.By calculating the irreversibility, it was found that the most important exergy loss was 6067.73 kW in the boiler unit. Keywords: Energy analysis, exergy analysis, steam boiler DOI: 10.7176/JSTR/7-09-03

Annual transient analysis of energetic, exergetic, and economic performances of solar cascade organic Rankine cycles integrated with PCM-based thermal energy storage systems

In this study, the annual transient analysis of the solar cascade organic Rankine cycle integrated with the phase change material (PCM) storage and parabolic trough collectors (PTC) has been conducted. The proposed system has been evaluated from energy, exergy, and economic points of view. Several PCMs, namely Isomalt, Adipic acid, Salicylic acid, Dimethylol propionic acid, A164, and KNO3–NaNO2–NaNO3 composition, have been compared to each other. Moreover, the effects of three different pairs of organic fluids, R245fa/R134a, R245fa/R500, and R245fa/R1234yf, have been examined on the system's performance. The annual investigation indicated that the closer the PCM melting temperature to the auxiliary heater setpoint temperature, the higher the solar fraction, exergy and energy efficiencies. Furthermore, the pair of R245fa/R500 had the best energy and exergy performances, which were 12.76% and 13.87%, respectively. The economic evaluation revealed that the case of R245fa/R500 combined with Dimethylol as the PCM thermal storage has the best economic performance with the NPV, LCOE, and PP of 186,622 $, 0.29 $/kWh, and 18 years, respectively. Also, the results of a sensitivity analysis showed that the NPV is extremely sensitive to the energy carriers prices and least sensitive to the PTC cost.

Energetic performance analysis on a membrane distillation integrated with low concentrating PV/T hybrid system

Membrane distillation seawater desalination technology has received widespread attention. However, this technology has problems such as high energy consumption and high initial temperature requirements. A membrane distillation seawater desalination system integrated with low-concentrating photovoltaic/thermal (LCPV/T-MD) modules was designed. With the help of concentrating photovoltaic panels and solar collectors, the working fluid required for membrane distillation is cascaded heating to obtain distilled fresh water. The integrated LCPV/T-MD mathematical model the hybrid experimental system were established, and the thermal, electrical performance, and water yield were analyzed. The results show that the greater ΔP, the lower of the salinity c, and the higher the inlet water temperature Tin, the greater the water yield. The LCPV/T-STC heating subsystem can heat the water temperature above 60 °C, and then auxiliary heating by heating rod can meet the requirements of MD system for inlet water temperature. In the experiment, the thermal efficiency and the electrical efficiency of the system can reach 56.2% and 15.9%, respectively. The GOR of the total LCPV/T-MD system can reach 0.69, and the MD subsystem water yield can reach 0.579 L/(h·m2). The findings can provide guidance for the further study of membrane distillation.

Energetic performance analysis of a solar-driven hybrid ejector cooling and humidification-dehumidification desalination system

One technique for improving energy efficiency is combining two or more energy systems to form a hybrid one that utilizes a single energy source. The use of renewable energy, such as solar heat to power hybrid systems, is another advantage. This paper introduces a novel hybrid ejector cooling-desalination system driven by an evacuated tube solar collector. The ejector cooling cycle (ECC) is combined with a closed-air, open-water, water-heated humidification dehumidification (HDH) desalination system. A thermodynamic model of the hybrid system has been developed, validated, evaluated, and presented in this paper, considering different refrigerants for the ejector cycle. The results indicate that the hybrid system achieved an energy utilization factor (EUF) of 1.4 with R600 as the ECC refrigerant. This represents the highest value (about 4–27%) than the other selected refrigerants. Hence, R600 is selected as the best refrigerant for the hybrid system. A case study of the hybrid system has been presented, considering several cities in Saudi Arabia using solar energy as the only source of energy. Results indicate about 15% energy input saving by the hybrid system for the specified outputs for Qassim city.

Energetic performance analysis of R466A as an alternative to R410A in VRF systems

In this study, utilization of R466A with low-GWP is investigated in variable refrigerant flow (VRF) systems. R410A is widely used in VRF systems. Only non-flammable refrigerants are allowed for these systems since they require high amount of refrigerant charge. However, most of refrigerants, which have low-GWP and may be suitable for air-conditioning systems, are flammable. The analysis was carried out for both cases of cooling mode and heating mode. Three evaporation temperatures (4, 8 and 12 °C) and three condenser temperatures (40, 50, 60 °C) were considered for cooling mode in the study. In heating mode, three different evaporation temperature values (−10, −5 and 0 °C) while single condenser temperature of 45 °C were used for the investigation. The results pointed out that both cooling capacity and heating capacity amounts of R466A were greater in comparison with R410A. COP values of R466A were determined as higher than R410A about by 5–15% and 4% in cooling mode and heating mode, respectively. Thus, R466A can be utilized as a suitable refrigerant for VRF systems and air-conditioners as an alternative to R410A. In the short term, R466A can be directly used without performing any constructional modification in the system operating with R410A.

Energetic and exergetic performance analysis of a solar driven power, desalination and cooling poly-generation system

This paper presents a thermodynamic analysis of a poly-generation system powered by solar thermal energy using parabolic trough collectors. The proposed system consists of an organic Rankine cycle, a multiple effect distillation and an absorption cooling unit. The performance analysis of the solar system is conducted for different configurations: power generation only, cogeneration power and cooling, cogeneration power and desalination, and poly-generation. The effects of turbine inlet temperature and pump inlet temperature on the energetic and exergetic system performance as well as the net power output and total exergy loss of the system are examined. In addition, exergetic parameters, including system total exergy loss, fuel depletion ratio and improvement potential were analyzed. The study reveals that increasing the turbine inlet temperature increases the performance while it reduces the total exergy destruction rate of the system. The result of the study also shows that the two main sources of exergy destruction are the solar thermal collector and desalination unit; with 49.3% of the input exergy (76% of the total exergy loss) destructed in the collector while 9.6% of the inlet exergy (14.9% of the total exergy loss) is destroyed in the desalination system. The overall improvement potential of the system was found to be 64.8%.

Energetic performance analysis of seawater desalination with a solar membrane distillation

In this paper, a study of the energy performance of a solar powered vacuum membrane distillation was investigated on four typical days that represent the four seasons of the year namely: the equinoxes (March 21st and September 21st) and the solstices (June 21st and December 21st), through the widely used energy criteria such as specific energy consumption, gained output ratio and heat recovery factor. The results indicate that the energy performance of the process is strongly linked to the solar irradiation and as long as the VMD is coupled with solar energy, the process could be competitive with industrialized desalination technologies such as RO, MSF and MED. Besides, the effect of the applied vacuum level on the specific energy consumption was examined. Obviously, the results reveal that for minimum SEEC an optimal vacuum pressure is between 5000 and 10000 Pa. As well a technique to optimize the energy performance by recycling hot cooling water, used for steam condensation, was discussed. An amelioration of about 35%, 26% and 31%, during the hottest day (June 21st) and of about 22%, 19% and 21%, during the coldest (December 21st) in the GOR, the SEC and the daily production could be achieved.

Comparative Analysis of Energetic Performance of Various Photovoltaic Power Stations

Comparative Analysis of Energetic Performance of Various Photovoltaic Power Stations