Energy, exergy, economic, and environmental (4E) analyses and optimization of a CCHP system with steam turbine

A parametric study has been carried out based on advanced exergy assessment for a parallel double‐effect LiBr–water absorption chiller. The advanced exergy method provides the real potential of the equipment for improvement in the system by recognizing the avoidable irreversibilities. The sensitivity analysis of various parts of the exergy destruction (endogenous avoidable, endogenous unavoidable, exogenous avoidable, and exogenous unavoidable) in system components and the overall performance (coefficient of performance, exergy efficiency, and modified exergy efficiency) of the system has been done to identify the actual potential of different components of the system to improve the overall performance of the system relative to operational parameters. Operational parameters include the heat source temperature, heat sink temperature, and the difference between the absorption and condensation temperature. The results showed that by modifying and improving the performance of components, 18.5% of the total exergy destruction of the system could be reduced. The modified exergy efficiency reduces sharply (nearly 40%) with the rising heat sink temperature. The endogenous exergy destruction increases in all system components except the condenser and evaporator by the heat source temperature increase. With the increase in the heat sink temperature, the avoidable part of the total exergy destruction in the system increases due to the significant rise in the avoidable exogenous exergy destruction in the components, and the unavoidable endogenous exergy destruction decreases (more than 200%) in the absorber. Increasing the condensation temperature reduces the unavoidable endogenous exergy destruction in the components except for the low‐temperature heat exchanger.

Section: System Configurationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sensitivity analysis of avoidable and unavoidable exergy destructions in a parallel double‐effect LiBr–water absorption cooling system

Zendehnam

Pourfayaz

2022

“…Therefore, further research is still needed to enhance the performance of building energy systems. One of the most effective ways to reduce energy consumption in buildings and, thus, to prevent the growth of Co 2 emission intensity, is combined heating, cooling, and power generation systems (CCHP), which recover the wasted energy 4,5 . Conventional power plants convert only about 30 percent of the energy in the fuel into electricity, and much of that energy is lost as heat.…”

Section: Introductionmentioning

confidence: 99%

“…One of the most effective ways to reduce energy consumption in buildings and, thus, to prevent the growth of Co 2 emission intensity, is combined heating, cooling, and power generation systems (CCHP), which recover the wasted energy. 4,5 Conventional power plants convert only about 30 percent of the energy in the fuel into electricity, and much of that energy is lost as heat. In addition, much energy is wasted due to the transfer of electrical power to the desired location.…”

Section: Introductionmentioning

confidence: 99%

Dynamic simulation of a solar ejector‐based trigeneration system using TRNSYS‐EES co‐simulator

Pourmoghadam

Mosleh

Karami

2022

In this paper, a new configuration of a solar combined cooling, heating, and power (CCHP) system is proposed to recover the waste thermal energy of a steam power plant, which provides the cooling and heating needs of an apartment complex located in Tehran. The required energy of the system is supplied by the parabolic trough solar collectors (PTCs) and, if necessary, an auxiliary heater is also used. An ejector refrigeration cycle (ERC) and a steam Rankine cycle are used for cooling and power generation, respectively. The cycle is dynamically modeled over a year using a TRNSYS‐EES co‐simulator. It is found that the highest Rankine cycle efficiency is obtained in the cold months (January) because of the decrease of turbine backpressure. With increasing the turbine inlet temperature from 190 to 210°C, the Rankine cycle and the overall cycle efficiencies increased about 1% and 2%, respectively. The maximum cooling, heating, and power generation, as well as the maximum solar fraction, are obtained at the turbine inlet temperatures of 210°C, which are 185.46, 598.65, 680.49 kW, and 70%, respectively. The annual overall performance and the solar fraction of the proposed CCHP system are 32.5% and 9.5%, respectively, based on 3000 m2 collector aperture area. The exergy analysis indicated that the maximum annual exergy destruction is related to the solar collectors, which have comprised 27% of the total exergy destruction. In addition, the yearly exergy efficiency of the proposed system is 39.9%.

Energetic/exergetic study of Kalina and refrigeration bottoming cycles on different solar‐driven organic Rankine cycles

Dehghan,

Akbari,

Montazerin

et al. 2024

Combination of different power cycle scenarios is of prime importance in achieving maximum energy utilization from solar‐driven multigeneration systems. To fulfill such objective, the present article proposes a novel energy distribution system, leveraging a combination of direct‐fed organic Rankine cycle (ORC) and a bottom‐cycled arrangement of Kalina cycle system (KCS) and double‐effect absorption refrigeration cycle (DEARC) within a parabolic trough solar collector powered trigeneration system. The study explores three different ORC configurations: simple ORC; ORC equipped with internal heat exchanger (ORC‐IHE) and regenerative ORC (RORC). It is shown that although higher efficiencies are achievable from a larger portion of PTSC energy absorbed by the ORC, the ORC energy absorption is limited by ORC evaporator temperature differences, and there is unused energy that can be recovered by the KCS, based on the proposed energy system. The results indicate that the addition of bottoming KCS leads to a considerable increase in the exergy efficiency of ORC, ORC‐IHE and RORC‐based systems by 11.7%, 30.7% and 32.6%, respectively. The impact of different ORC configurations, key ORC parameters and various organic working fluids on the energetic/exergetic efficiencies is also examined to find the optimal configuration. In terms of overall energetic/exergetic efficiencies, the highest performance belongs to ORC (78.4%/30.4%) while the lowest energetic and exergetic efficiencies belong to ORC‐IHE and RORC, respectively (56.3% and 25.65%). On the basis of a comparative study with the available literature, these values are higher than what is already reported for similar solar‐driven multigeneration systems. Appropriate thermal match and lower exergy destruction in the KCS, and bottoming cycle arrangement of the DEARC are the main reasons for such enhanced performance. This research not only contributes valuable insights into efficient solar‐driven systems but also sets a new benchmark for performance metrics in the existing literature.