Energy and Exergy Efficiency Analysis of Fluid Flow and Heat Transfer in Sinter Vertical Cooler

In order to fully understand the energy and exergy transfer processes in sinter vertical coolers, a simulation model of the fluid flow and heat transfer in a vertical cooler was established, and energy and exergy efficiency analyses of the gas–solid heat transfer in a vertical cooler were conducted in detail. Based on the calculation method of the whole working condition, the suitable operational parameters of the vertical cooler were obtained by setting the net exergy efficiency in the vertical cooler as the indicator function. The results show that both the quantity of sinter waste heat recovery (SWHR) and energy efficiency increased as the air flow rate (AFR) increased, and they decreased as the air inlet temperature (AIT) increased. The increase in the sinter inlet temperature (SIT) resulted in an increase in the quantity of SWHR and a decrease in energy efficiency. The air net exergy had the maximum value as the AFR increased, and it only increased monotonically as the SIT and AIT increased. The net exergy efficiency reached the maximum value as the AFR and AIT increased, and the increase in the SIT only resulted in a decrease in the net exergy efficiency. When the sinter annual production of a 360 m2 sintering machine was taken as the processing capacity of the vertical cooler, the suitable operational parameters of the vertical cooler were 190 kg/s for the AFR, and 353 K for the AIT.

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Energy and Exergy Analyses of Tube Banks in Waste Heat Recovery Applications

Energies ◽

10.3390/en11082094 ◽

2018 ◽

Vol 11 (8) ◽

pp. 2094 ◽

Cited By ~ 7

Author(s):

Mustafa Erguvan ◽

David MacPhee

Keyword(s):

Energy Efficiency ◽

Reynolds Number ◽

Heat Recovery ◽

Waste Heat ◽

Cross Flow ◽

Exergy Efficiency ◽

Circular Cylinders ◽

Published Data ◽

Energy And Exergy ◽

Exergy Analyses

In this study, energy and exergy analyses have been investigated numerically for unsteady cross-flow over heated circular cylinders. Numerous simulations were conducted varying the number of inline tubes, inlet velocity, dimensionless pitch ratios and Reynolds number. Heat leakage into the domain is modeled as a source term. Numerical results compare favorably to published data in terms of Nusselt number and pressure drop. It was found that the energy efficiency varies between 72% and 98% for all cases, and viscous dissipation has a very low effect on the energy efficiency for low Reynolds number cases. The exergy efficiency ranges from 40–64%, and the entropy generation due to heat transfer was found to have a significant effect on exergy efficiency. The results suggest that exergy efficiency can be maximized by choosing specific pitch ratios for various Reynolds numbers. The results could be useful in designing more efficient heat recovery systems, especially for low temperature applications.

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Energy and Exergy Performance Comparative Analysis of Solar Driven Organic Rankine Cycle Using Different Organic Fluids

Journal of Energy Resources Technology ◽

10.1115/1.4050343 ◽

2021 ◽

pp. 1-38

Author(s):

Md. Tareq Chowdhury ◽

Esmail M. A. Mokheimer

Keyword(s):

Energy Efficiency ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Exergy Efficiency ◽

Optimum Operating ◽

Inlet Temperature ◽

Turbine Inlet Temperature ◽

Turbine Inlet ◽

Energy And Exergy ◽

Organic Fluids

Abstract In this study, the performance of Parabolic Trough Collector (PTC) integrated with Organic Rankine Cycle (ORC) is investigated to find the optimum operating scenarios and to assess the exergy destruction at different components of the system. Commercial PTC LS-2 model with Therminol VP-1 as heat transfer fluid was integrated with an organic Rankine cycle that was examined for its thermal and exergetic performance using different organic fluids. It was found that every fluid has an optimum pressure and temperature level at which it works better than other fluids. R134a (Tetrafluoroethane, CH2FCF3) showed the best performance for the turbine inlet temperature range from 340 K — 440 K regarding the achieved energy and exergy efficiencies. At a temperature of 362.8 K and a pressure of 2750 kPa, R134a showed the highest energy efficiency of 8.55% and exergy efficiency of 21.84% with the lowest mass flow rate required in ORC. Energy efficiency of other fluids namely, R245fa (Pentafluoropropane, CF3CH2CHF2), n-pentane and Toluene were less than 5%. On the other hand, Toluene exhibited thermal efficiency of 23.5 % at turbine inlet temperature of 550 K and pressure of 2500 kPa, while the exergy efficiency was 62.89 % at solar irradiation of 1 kW/m2.

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A Numerical Case Study: Effect of Heat Leakage on Thermodynamic Efficiency of Cylinders in Cross-Flow

Journal of Heat Transfer ◽

10.1115/1.4042156 ◽

2018 ◽

Vol 141 (2) ◽

Cited By ~ 3

Author(s):

Mustafa Erguvan ◽

David W. MacPhee

Keyword(s):

Energy Efficiency ◽

Reynolds Number ◽

Cross Flow ◽

Exergy Efficiency ◽

Thermodynamic Efficiency ◽

Inlet Temperature ◽

Heat Leakage ◽

Lower Reynolds Number ◽

Energy And Exergy ◽

Artificial Heat

Numerical and thermodynamic analyses have been undertaken in this study to examine energy and exergy efficiencies of in-line tube banks for unsteady cross-flow. Pitch ratio (PR) and the number of in-line tubes are varied for Reynolds numbers of 500 and 10,000, and artificial heat leakages are modeled as a source term. Numerical results are compared with published values, and good agreements are obtained regarding Nusselt number and pressure drop. Whereas the energy efficiency varied between 72% and 99%, the exergy efficiency ranged from 40% to 70%. It was found that while viscous dissipation has a low effect on energy and exergy efficiencies for the lower Reynolds number, it has a significant effect for the higher Reynolds number. On the other hand, heat leakage had a greater effect on exergy efficiency compared to energy efficiency, especially for the lower Reynolds number case. Overall, this study verified how heat leakage could play a vital role on efficiency for low-inlet temperature heat recovery systems.

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