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Figure 34. Rankine circle with reheat of superheated steam [74]

Figure 34 Rankine circle with reheat of superheated steam [74]

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Table 2. Overview of recent studies carried out on Printed Circuit Heat Exchangers
Table 2. Overview of recent studies carried out on Printed Circuit Heat Exchangers
Figure 4. Improved structure: rectangular and hollow channel plate structure [7]
Figure 4. Improved structure: rectangular and hollow channel plate structure [7]
Figure 5. Geometry of PCHE: (a) Straight, zigzag, and wavy types; (b) airfoil type [8]
Figure 5. Geometry of PCHE: (a) Straight, zigzag, and wavy types; (b) airfoil type [8]
Table 3. Geometric data of physical models (Wang et al. [10]).
Table 3. Geometric data of physical models (Wang et al. [10]).
Figure 12. Structure and geometry parameters of PCHE channel with NACA (National Advisory Committee for Aeronautics) airfoil fins [Airfoil fin structure parameters (arc height hl, maximum arc height position Il, airfoil thickness tl), Airfoil fin arrangement parameters (airfoil fin horizontal spacing Lh and airfoil fin vertical spacing Lv), Airfoil chord LI] [11]
Figure 12. Structure and geometry parameters of PCHE channel with NACA (National Advisory Committee for Aeronautics) airfoil fins [Airfoil fin structure parameters (arc height hl, maximum arc height position Il, airfoil thickness tl), Airfoil fin arrangement parameters (airfoil fin horizontal spacing Lh and airfoil fin vertical spacing Lv), Airfoil chord LI] [11]
Figure 13. Computational grids of AF-PCHE channel [11]
Figure 13. Computational grids of AF-PCHE channel [11]
Figure 14. Geometrical and Meshing models of the geometry adopted [12]
Figure 14. Geometrical and Meshing models of the geometry adopted [12]
Figure 22. Shapes and sizes of the PCHE channel (unit: mm) [21]
Figure 22. Shapes and sizes of the PCHE channel (unit: mm) [21]
Int. Res. J. Multidiscip. Technovation, 5(3) (2023) 11-48 | 29
Int. Res. J. Multidiscip. Technovation, 5(3) (2023) 11-48 | 29
Where j, Nu, Pr and fare given respectively by 2quations (24, 25, 26, 27). Li et al. [12] used equation (28) for calculation of thermal performance index (TPF) of heat exchanger to carried out performance analysis of a semi-circular cross-section zigzag channel PCHE with supercritical methane as working fluid.
Where j, Nu, Pr and fare given respectively by 2quations (24, 25, 26, 27). Li et al. [12] used equation (28) for calculation of thermal performance index (TPF) of heat exchanger to carried out performance analysis of a semi-circular cross-section zigzag channel PCHE with supercritical methane as working fluid.
Brayton and Rankine cycles are respectively used in gas and steam turbines. They are used to describe the performance as well as optimize the performance of gas and steam systems that depends on heating and cooling applications to increase/maximize the outputs of these power generation systems. Figures 23 and 24 respectively show closed-cycle system of components and process diagrams for Brayton cycle. Figures 25 and 26 respectively show cycle system of components and process diagrams for Rankine cycle. The Brayton cycle is more efficient than the Rankine cycle, but the Rankine cycle can generate more power because it uses water as its working fluid (Ighodaro and Osikhuemhe [59]). Table 5 compares Brayton and Rankine cycles.
Brayton and Rankine cycles are respectively used in gas and steam turbines. They are used to describe the performance as well as optimize the performance of gas and steam systems that depends on heating and cooling applications to increase/maximize the outputs of these power generation systems. Figures 23 and 24 respectively show closed-cycle system of components and process diagrams for Brayton cycle. Figures 25 and 26 respectively show cycle system of components and process diagrams for Rankine cycle. The Brayton cycle is more efficient than the Rankine cycle, but the Rankine cycle can generate more power because it uses water as its working fluid (Ighodaro and Osikhuemhe [59]). Table 5 compares Brayton and Rankine cycles.
CMPR — air compressor: CMB — combustor: EG; — gas turbine electric generator: HRSG — heat recovery steam generator: EG) — steam turbine electric generator: COND — condenser: P — pump
CMPR — air compressor: CMB — combustor: EG; — gas turbine electric generator: HRSG — heat recovery steam generator: EG) — steam turbine electric generator: COND — condenser: P — pump
Table 6. Thermal efficiency calculation models of four cycles (Figures 30 and 31) [60]
Table 6. Thermal efficiency calculation models of four cycles (Figures 30 and 31) [60]
SR, split ratio; nm, efficiency of the motor that drives the compressor; 116, efficiency of the electric generator that is connected to the turbine for power generation.
SR, split ratio; nm, efficiency of the motor that drives the compressor; 116, efficiency of the electric generator that is connected to the turbine for power generation.
Figure 36. Schematics of a reheat ORC system: (A) system schematic and (B) T-S diagram [71]
Figure 36. Schematics of a reheat ORC system: (A) system schematic and (B) T-S diagram [71]
Figures 28 and 29 respectively show components and process diagrams for combined cycle power plant of gas turbine and steam turbine in which the waste heat energy in exhaust gases from the gas turbine is utilized for power generation by the application of HRSG and steam turbine (Tarasova et al. [70]). The formulation of performance or optimization parameter varies according to the optimization processes involve in getting the maximum efficiency from particular industrial application. For example, Table 6 provides different efficiency formulations involving the use of Brayton
Figures 28 and 29 respectively show components and process diagrams for combined cycle power plant of gas turbine and steam turbine in which the waste heat energy in exhaust gases from the gas turbine is utilized for power generation by the application of HRSG and steam turbine (Tarasova et al. [70]). The formulation of performance or optimization parameter varies according to the optimization processes involve in getting the maximum efficiency from particular industrial application. For example, Table 6 provides different efficiency formulations involving the use of Brayton
Rankine cycle power efficiency can be increased by selection of optimum increased pressure of boiler/evaporator, by selection of optimum decreased pressure of condenser, by making use of the processes of reheating and superheating possible with steam turbine expansion, and by adoption the process of heat regeneration. Rankine cycle power efficiency can also be increased by using supercritical Rankine cycle which is applicable to SCWRs and supercritical fossil fuel power plants.
Rankine cycle power efficiency can be increased by selection of optimum increased pressure of boiler/evaporator, by selection of optimum decreased pressure of condenser, by making use of the processes of reheating and superheating possible with steam turbine expansion, and by adoption the process of heat regeneration. Rankine cycle power efficiency can also be increased by using supercritical Rankine cycle which is applicable to SCWRs and supercritical fossil fuel power plants.
Table 7. Brief description of heat transfer devices/systems used for specific industrial applications (Patel et al. [75], Zohuri [76]).
Table 7. Brief description of heat transfer devices/systems used for specific industrial applications (Patel et al. [75], Zohuri [76]).
Figure 41. The configuration of the recompression cycle [78], [19]
Figure 41. The configuration of the recompression cycle [78], [19]
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