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• Gasses are proposed and analyzed as solar heat transfer fluids in a commercial PTSC. • Energetic and exergetic modeling of the proposed system is presented. • Output is increased from 1148.86 kW to 1442.66 kW by rise of SHTF from 525 to 645 °C. • Exergy efficiency is increased from 5.74% to 8.39% when x rises from 0.5 to 0.9. • System produces 34.07% exergy with 64.01% exergy destroyed and 1.92% exergy loss. This communication develops a novel cooling-power cogeneration system consisting of a parabolic trough collector utilizes gasses as the medium for solar to heat conversion, and the Kalina cycle integrated series-flow double effect LiBr-H 2 O absorption chiller to generate electricity and large cooling, simultaneously. By developing a thermal model, a simulation through EES is conducted to investigate the influence of internal tube diameter of absorber and solar irradiation on the exit temperature of SHTF and flowing mass of the working fluid of Kalina cycle. It is determined that for the given inlet temperature and solar irradiation, the outlet temperature of SHTF is declined when the internal diameter of absorber tube is increased. The effect of change in SHTF, pressure at expander entry, and the concentration of ammonia-water basic solution on electrical power produced, refrigeration capacity, exergy of refrigeration, efficiencies of the cogeneration cycle are investigated. The cogeneration cycle with helium operated PTSC indicates better results than the use of air and CO 2 as SHTF. Increase in the outlet temperature of SHTF (helium) leads to considerable increase in electrical power, refrigeration capacity, and exergy of refrigeration. The breaking down of solar exergy supplied to developed configuration reveals an exergy destruction of the order of 64.01% along with the exergy loss to environment of 1.92%, and exergy of refrigeration of 4.65% with generated power exergy of 29.42%, respectively. The computational results of present investigation are compared with the theoretically published data and a good agreement is found between these data. [ABSTRACT FROM AUTHOR]

• New design of central receiver is proposed to enhance the rate of solar to heat conversion. • Energetic and exergetic modeling is presented for the combined power and refrigeration system. • DNI and coil diameter have a significant effect on variation of temperature of oil in the receiver. • Performance of the system is influenced at large by the change in type of ORC working fluid. This communication presents the implementation of a central receiver where helically coiled tubes are employed in order to enhance the rate of solar to heat conversion, which is the energy source that drives a cogeneration cycle which consists of organic Rankine cycle and the ejector-absorption refrigeration cycle. A numerical simulation with the application of computational fluid dynamics using the ANSYS-FLUENT package was conducted to examine the effect of the coil diameter and inlet oil (Duratherm 600) temperature on the pressure and temperature of solar heat transfer fluid (SHTF) which leaves the receiver. It is found that for inlet temperature of 92°C and direct normal irradiations of 850 W/m2, the outlet temperature of solar heat transfer fluid is raised by 9% when the coil diameter increased from 150 to 400 mm. Further, cogeneration cycle response to altering operating parameters is also investigated. From 100% radiative solar energy supplied to cogeneration cycle, it is revealed that fluids of organic Rankine cycle; R141b, R600a, and R143a produce the energetic output as 20.64%, 15.04%, and 8.33%, respectively, and the remaining solar input energy is lost to environment through temperature difference. The exergy distribution shows that for R141b operated cycle out of 100% solar exergy, 16.79% is produced as exergetic output, 81.94% is the exergy destroyed, and the remaining 1.27% is the exergy loss. [ABSTRACT FROM AUTHOR]

An integrated system for simultaneous production of triple-effect cooling and single stage heating is proposed in this paper to harness low grade solar energy. The proposed system combines the heliostat field with a central receiver and the ejector-absorption cycle with the shaft power driven transcritical CO 2 cycle. A parametric study based on first and second laws of thermodynamics is carried out to ascertain the effect of varying the exit temperature of duratherm oil, turbine inlet pressure, and evaporators temperature on the energy and exergy output as well as on the energy and exergy efficiencies of the system. The results obtained indicate that major source of exergy destruction is the central receiver where 52.5% of the inlet solar heat exergy is lost followed by the heliostat where 25% of the inlet exergy is destroyed. The energy and exergy efficiencies of the integrated system vary from 32% to 39% and 2.5%–4.0%, respectively, with a rise in the hot oil outlet temperature from 160 °C–180 °C. It is further shown that increase in evaporator temperature of transcritical CO 2 cycle from −20 °C to 0 °C increases the energy efficiency from 27.45% to 43.27% and exergy efficiency from 2.51% to 2.97%, respectively. The results clearly show how the variation in the values of hot oil outlet temperature, turbine inlet pressure, and the evaporator temperature of transcritical CO2 cycle strongly influences the attainable performance of the integrated system. [ABSTRACT FROM AUTHOR]

Abstract: In the proposed cogeneration cycle, a LiBr–H2O absorption refrigeration system is employed to the combined power and ejector refrigeration system which uses R141b as a working fluid. Estimates for irreversibilities of individual components of the cycle lead to possible measures for performance improvement. Results of exergy distribution of waste heat in the cycle show that around 53.6% of the total input exergy is destroyed due to irreversibilities in the components, 22.7% is available as a useful exergy output, and 23.7% is exhaust exergy lost to the environment, whereas energy distribution shows 44% is exhaust energy and 19.7% is useful energy output. Results also show that proposed cogeneration cycle yields much better thermal and exergy efficiencies than the previously investigated combined power and ejector cooling cycle. Current investigation clearly show that the second law analysis is quantitatively visualizes losses within a cycle and gives clear trends for optimization. [Copyright &y& Elsevier]

Abstract: A conceptual trigeneration system is proposed based on the conventional gas turbine cycle for the high temperature heat addition while adopting the heat recovery steam generator for process heat and vapor absorption refrigeration for the cold production. Combined first and second law approach is applied and computational analysis is performed to investigate the effects of overall pressure ratio, turbine inlet temperature, pressure drop in combustor and heat recovery steam generator, and evaporator temperature on the exergy destruction in each component, first law efficiency, electrical to thermal energy ratio, and second law efficiency of the system. Thermodynamic analysis indicates that exergy destruction in combustion chamber and HRSG is significantly affected by the pressure ratio and turbine inlet temperature, and not at all affected by pressure drop and evaporator temperature. The process heat pressure and evaporator temperature causes significant exergy destruction in various components of vapor absorption refrigeration cycle and HRSG. It also indicates that maximum exergy is destroyed during the combustion and steam generation process; which represents over 80% of the total exergy destruction in the overall system. The first law efficiency, electrical to thermal energy ratio and second law efficiency of the trigeneration, cogeneration, and gas turbine cycle significantly varies with the change in overall pressure ratio and turbine inlet temperature, but the change in pressure drop, process heat pressure, and evaporator temperature shows small variations in these parameters. Decision makers should find the methodology contained in this paper useful in the comparison and selection of advanced heat recovery systems. [Copyright &y& Elsevier]