•R1270/CuO nano-refrigerant is applied for the first time on proposed system.•Pressure drop and booster pressure ratio is optimized for each operating condition.•Maximum exergy efficiency and COP are ...found to be 9.47% and 9.46%, respectively.•Proposed calculation procedure is proven with a maximum inconsistency of 4.17%.•There is a maximum COP improvement of 29.32% compared to studies in the literature.
Ejector expansion refrigeration systems have gained prominence in the refrigeration sector, providing much better thermodynamic performance than conventional refrigeration systems. The present work aims to improve the thermodynamic performance of a booster assisted ejector expansion vapour compression refrigeration system with constant area mixing theory for low-temperature applications using R1270/CuO nano-refrigerant. Comparative energy and exergy based thermodynamic analysis of pure refrigerant and nano-refrigerant (2 wt% of CuO to R1270) systems are carried out. The pressure drop in the receiver part of the ejector and pressure ratio of the booster compressor are optimized for different operating conditions. The optimized results pointed out that the system using nano-refrigerant is the best one for which the proposed system has 8% lower discharge temperature of the main compressor, 0.59% lower ejector area ratio, 3.23% lower entrainment ratio, 8.93% higher exergy efficiency, 8.96% higher COP (Coefficient of Performance) and 21.23% lower total exergy destruction than pure refrigerant-based system at a condenser temperature of 45 °C and an evaporator temperature of −30 °C. Furthermore, there is a minimum COP improvement of 14.42% and a maximum COP improvement of 29.32% compared to research studies in the literature under identical operating conditions. The proposed calculation procedure has maximum deviation of 4.17% compared to experimental studies in the literature. Therefore, it can serve as a useful guide for performing the theoretical analysis of nano-refrigerant based ejector expansion refrigeration systems before setting up an experimental system.
•For the first time, nanoparticles have been added into the cascade cycles.•An 6.37 % increase in performance was achieved with nano-refrigerant application.•With nano-refrigerant the emission of the ...CO2 has decreased by 13.03 %.
There is a lack of research in the literature on the application of nanoparticles to different cascade cycle configurations with environmental refrigerants in ultra-low temperature refrigeration applications. This study is the first on the use of nano-refrigerants in cascade refrigeration cycles. In this study, the effect of 2 wt.% of CuO to RE170 and R170-pure refrigerant utilization in cascade vapor compression refrigeration cycle (CVCRC), cascade ejector refrigeration cycle (CERC) and cascade ejector intercooler refrigeration cycle (CEIRC) are investigated to achieve higher performance values in ultra-low temperature applications. For CVCRC, CERC and CEIRC, the increases in terms of coefficient of performance (COP) with the use of nano-refrigerant were found to be 12.77 %, 8.20 %, and 6.37 %, respectively, and 18.55 %, 14.05 %, and 6.07 %, for exergy efficiency. Upon scrutinizing the results with nano-refrigerant in relation to the COP, the analysis revealed that the CEIRC cycle exhibited an improvement ranging from 13.43 % to 20.49 % in comparison to CERC. Additionally, with nano-refrigerant, the CEIRC cycle demonstrated an increase ranging from 42.39 % to 75.41 % when compared to CVCRC in COP. It was observed that the utilization of CEIRC led to a 13.03 % decrease in kg CO2 emissions in compared to CERC and a reduction of 32.53 % compared to CVCRC with using nano-refrigerant.
In this study, a novel thermoeconomic optimization method that is simple and efficient, for real complex cycles is introduced. First, a thermoeconomic analysis method that is called non-linear ...simplex direct search method is improved for the purposes of this study. The objective of this paper is to apply this method to four cogeneration cycles that are simple cycle, inlet air cooling cycle, air preheated and air-fuel preheated cycles for analyzing and optimizing. The four cycles are thermoeconomically optimized for constant power and steam mass (30 MW and 14 kg/s saturated steam flow rate at 2000 kPa), for constant power (30 MW) and for variable steam mass, and for variable power and steam mass by using the cost equation method and the effect of size on equipment method. The results obtained by the effect of size on equipment and by the cost equations methods are very different from each other. For the case of global optimization, the optimum electricity costs which also correspond to minimum are obtained as 0,0432 $/kWh for simple cycle, 0,0514 $/kWh for inlet air cooling cycle 0,0577 $/kWh for air preheated cycle and 0,058 $/kWh for air-fuel preheated cycle by using cost equations method.
•A simple and efficient optimization procedure is introduced for thermal systems.•Four types of cogeneration cycles are optimized thermoeconomically with new method.•Local and global thermoeconomic optima are found, compared and discussed.•The electricity costs at local optima are higher than global optima.•The lowest electricity cost is obtained as 0,0432 $/kWh for simple cycle.
The present study introduces a novel cascade ejector intercooler refrigeration cycle (CEIRC) and a novel cascade ejector booster refrigeration cycle (CEBRC), which are designed to improve ultralow ...temperature (ULT) refrigeration system performance based on various refrigerants in terms of energy, exergy, and environment. Through the analysis conducted with eco‐friendly refrigerants for CEIRC, the refrigerant pair exhibits the highest performance that is found to consist of RE170 for high‐temperature cycles and R170 for low‐temperature cycles. These refrigerants have very low global warming potential and are eco‐friendly. The coefficient of performance (COP) reveals improvements of 3.20–9.51%, 10.55–19.12%, and 31.96–65.97% over the CEBRC, cascade ejector refrigeration cycle (CERC), and cascade vapor compression refrigeration cycle (CVCRC), respectively, resulting in corresponding exergy efficiency improvements of 3.18–9.49%, 10.48–19.12%, and 31.87–65.98%. The total compressor power and exergy destruction are also compared, indicating that the CEIRC exhibits the best performance among the four. CEIRC achieves a COP increase of 11.6% compared with the cascade refrigeration cycle, which is considered the cycle with the highest performance operating at ultralow temperatures in the literature, which is CERC. The kg CO2 effect of the CEIRC is 11.35% lower than that of the CERC.
The current investigation presents a novel cascade ejector intercooler refrigeration cycle (CEIRC) that is intended to enhance the performance of ultralow temperature refrigeration systems. The CEIRC demonstrates a noteworthy enhancement in the coefficient of performance, with a discernible increase of 11.6% in comparison to the cascade refrigeration cycle within the existing literature.
•Solar-driven EEVCRS with R152a/Cu was proposed for the first time.•Thermodynamic optimization and analysis of proposed system were carried out.•COP and exergy efficiency rose by a maximum of ...14.05%.•Total exergy destruction reduced by a maximum of 34.48%.•Solar panel area reduced by a maximum 14.27%.
Conventional vapour compression refrigeration systems require high electrical energy for low temperature applications. For the first time in the literature to reduce this required energy, comprehensive thermodynamic analysis and optimization of booster-assisted ejector expansion vapour compression refrigeration system with R152a/Cu nano-refrigerant are presented for low-temperature applications. Solar panels are used to cover the total compressor work, using the climate data of Izmir, Turkey. According to the thermodynamic optimization findings, the use of nanoparticles in the refrigeration system led to several improvements when compared to the R152a refrigeration system. These enhancements include a reduction of 6.52-11.71% in the main compressor discharge temperature, a decrease of 18.46-34.48% in the total exergy destruction rate, an increase of 3.08-4.04% in the entrainment ratio, a reduction of 0.089-3.25% in the ejector area ratio, a decrease of 8.34-14.27% in the panel area, and an increase of 8.09-14.05% in both the coefficient of performance and exergy efficiency. Another thing worth mentioning is that coefficient of performance and exergy efficiency improved by 2.06% and 1.96%, respectively, while total exergy destruction reduced by 4.83% compared to our previous study. The results obtained from the thermodynamic optimisation provide a useful reference for the design of an experimental system, as they provide evidence of model validity and can guide the implementation of the system.
The most obvious disadvantage of lignites is high water content (25-65%). In this study, experiments were carried out to determine the mechanical dewatering characteristics of Konya Ilgın lignite, ...which has 8935 kJ/kg low heating value and 45.15% water content. The main parameters investigated in the dewatering experiments were water/dry lignite ratio, pressure, and duration of compression. The tests were carried out by varying time from 5 to 20 min and by varying pressure from 100 to 600 bar. Results showed that the dewatering rate increased with the increase of water/dry lignite ratio, pressure, and duration of compression. The increase was not linear and tend to decrease with an increase in each variable. Pressure was more effective than duration of compression for reducing final moisture content.
In this study eight methods are evaluated for a gas turbine cogeneration cycle to improve the efficiency. These methods are increasing gas turbine inlet air temperature, cooling the inlet air of the ...compressor, air preheating, fuel preheating, increasing compressor inlet air pressure, increasing air excess rates, steam injection, and humidification of the inlet air of the compressor. These methods are studied in order to compare their effects on the performance of the systems. The effects of these methods on the exergetic efficiency depend on the kind of the cogeneration cycle. By combining recuperation, preheating fuel and steam injection methods high efficiency can be achieved. The combined methods give the best results under variable heat demands of the market. An appropriate combination of the efficiency improvement methods may increase the exergetic efficiency about 20 %. The results show that efficiency improvement methods must be applied together whenever it is possible.
U radu se procjenjuje osam metoda za poboljšanje učinkovitosti kogeneracijskog ciklusa plinske turbine. Tim se metodama povećava temperatura ulaznog zraka plinske turbine, rashlađuje ulazni zrak ...kompresora, predgrijava zrak, predgrijava gorivo, povećava tlak ulaznog zraka kompresora, povećava brzina viška zraka, ubrizgava para i vlaži ulazni zrak kompresora. Te se metode istražuju kako bi se usporedilo njihovo djelovanje na performanse sustava. Učinci tih metoda na egzergetsku učinkovitost ovise o vrsti kogeneracijskog ciklusa. Kombiniranjem metoda rekuperacije, predgrijavanja goriva i ubrizgavanja pare može se postići visoka učinkovitost. Kombinirane metode daju najbolje rezultate kod različitih potreba tržišta za toplinom. Odgovarajućom kombinacijom metoda za poboljšanje učinkovitosti može se povećati egzergetska učinkovitost za oko 20 %. Rezultati pokazuju da se metode za poboljšanje učinkovitosti moraju primijeniti zajedno kada je god to moguće.
•Low global warming potential refrigerants in CRS are studied.•R41-RE170 performs better for use of CRS at low temperatures.•The performance of R41-R423A in CRS is poorer than that of other ...refrigerant pairs.•RE170 is proposed as alternative refrigerant to R423A in upper cycle.•There is maximum COP improvement of 13.05% compared to studies in literature.
This study examines a variety of evaluation criteria such as various operating and design parameters for thermodynamic performance of a cascade refrigeration system (CRS). R41 is used in low-temperature circuit (LTC), whereas R1243zf, R423A, R601, R601A, R1233zd (E) and RE170 are used for the first time in this study and are adapted for a high-temperature circuit (HTC). This study with four aims are conducted: (1) to analyse refrigerant pairs with low global warming potential (GWP) to further contribute to the literature; (2) to investigate the impact of various operating parameters on system performance; (3) to suggest potential alternative refrigerant to R423A; (4) to also compare the performance of the refrigerant pairs used in this study with those analysed by researchers in the literature. The results demonstrate that condenser and evaporator temperature ranges have a significant effect on the performance parameters studied in the system designed for six refrigerant pairs. The greatest reduction in COP occurs in R41-R423A with about 43.85% in a change of 10°C in the condenser temperature. A change of 10°C in the evaporator temperature causes the COP of the CRS to rise by approximately 19% for all refrigerant pairs. For applications that desire low temperatures, R41-R423A exhibits the lowest COP and exergy efficiency with 1.105 and 33.93%, respectively, whereas R41-RE170 presents the highest COP and exergy efficiency with 1.210 and 37.18%, respectively. Furthermore, exergy destruction in HTC compressor is made up almost to one-third of total exergy destruction. RE170 is proposed as an alternative refrigerant for R423A by the reason of its low environmental detriment and superior performance. Furthermore, there is a maximum COP improvement of 13.05% compared to studies in the literature.
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