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The study investigates the comprehensive effects of superheat and internal heat exchanger (IHX) on the thermo-economic performance of organic Rankine cycle (ORC). Exergy efficiency, net power output, and electricity production cost (EPC) are compared based on the working fluid properties and heat sources. The results indicate that under a lower heat source temperature and load, exergy efficiency of...
Film cooling, as an effective protection technology, is widely applied in gas turbines to prevent components like vane blades from the hot mainstream. However, ash and other contaminants contained in the gas easily deposit on blade surfaces, which results in blockages inside the film holes and a reduction of the coverage area of the coolant air. Two blockage configurations (hemispherical and tetrahedral...
The heat transfer deterioration (HTD) of supercritical CO2 encountered in trans-critical CO2 Rankine cycle is an important issue related the safety of the whole unit. For the purpose, numerical simulations are performed to get a further insight into the mechanism of heat transfer characteristics of supercritical CO2 flow in helically coiled tube (HCT) both in horizontal and vertical orientations with...
With the increasing demand of energy saving and emission reduction, low temperature economizer (LPE) is more and more utilized in the heat recovery plant of the coal-fired power plant and because of the obvious advantages in material properties the use of fluorine plastics low temperature economizer has gradually become extensive. In this paper the equivalent heat drop method is utilized to calculate...
The cost of heat exchangers account for a large proportion of total investment in organic Rankine cycle (ORC). In this paper, plate heat exchanger (P), shell-and-tube heat exchanger (S) and finned-tube heat exchanger (F) are used as evaporator and condenser of four subcritical ORC configurations: ORC-PP, ORC-SS, ORC-FP and ORC-FS. The thermo-economic models are built and a thermo-economic evaluation...
In aim to reduce the greenhouse-gas emissions and improve the low-grade heat efficiency, a modified CCHP (combined cooling, heating, and power) system is proposed using supercritical CO 2 . This cycle combines a Brayton cycle and a transcritical ejector refrigeration cycle by adding an extraction turbine. A mathematical model is developed to simulate the modified CCHP system. Parametric analysis...
A multi-objective function F(X) by the incorporation of single-objective functions, i.e., net power output Wnet, exergy drop of the exhaust gas from inlet to outlet ΔEg, total exergy destruction rate I and system total cost C2013, has been put forward as the subcritical organic Rankine cycle (ORC) performance indicator and solved with the method of linear weighted evaluation function. The optimization...
The performance of the ORC (organic Rankine cycle) systems using zeotropic mixtures as working fluids for recovering waste heat of flue gas from industrial boiler is examined on the basis of thermodynamics and thermo-economics under different operating conditions. In order to explore the potential of the mixtures as the working fluids in the ORC, the effects of various mixtures with different components...
The low-grade heat sources coupled by ORC (organic Rankine cycle) are categorized into two groups. For the first one, the inlet temperature and the mass flow rate are known, and the working mass of the heat source is directly discharged after being used. For the second, the heat release is specific and the working mass of the heat source is usually recycled after releasing heat. The theoretical formulas...
This paper presents an economical evaluation and parametric optimization on subcritical ORC (organic Rankine cycle) system for recovering the low-temperature waste heat of flue gas which is released from industrial boilers. First, the effects of the PPTD (pinch point temperature difference) in evaporator and condenser, and evaporating temperature on the system performance are examined with the EPC...
Two modified systems based on a KCS (Kalina cycle system) 11 with a two-phase expander to substitute a throttle valve are proposed. The two-phase expander is located between the regenerator and the absorber in the B-modified cycle and between the separator and the regenerator in the C-modified cycle. A thermodynamic performance analysis of both the original KCS 11 and the modified systems is carried...
The thermal performance of supercritical pressure ORCs (Organic Rankine Cycles) is related to the critical temperature of the organic fluids. The heat source in this investigation was flue gas with an inlet temperature of 150 °C and an outlet temperature of 70 °C. The working fluids were R218, R134a and R236fa. An integrated-average temperature difference was used to quantify the thermal match between...
The LCA (life-cycle assessment) was applied to evaluate EI (the environmental impact) of ORCPW (organic Rankine cycle power-plant for waste-heat-recovery) in this paper. The model of LCA on the ORCPW was established. The life-cycle of ORCPW was divided into construction, operation and decommissioning phases. The inventory of environmental emissions was listed for the ORCPW with 7 different working...
Organic Rankine cycle (ORC) is a promising technology for converting low-grade waste heat into the electricity. This paper carries out an exergoeconomic analysis and performance optimization of a condenser for a binary mixture of vapors in the ORC system. In this model, the exergy loss due to heat transfer between a binary mixture of vapors and the cold fluid is taken into account and other exergy...
A theoretical formula is proposed to calculate the OET (optimal evaporation temperature) of subcritical ORC (organic Rankine cycle) based on thermodynamic theory when the net power output is selected as the objective function. The OETs of 22 working fluids including wet, isentropic and dry fluids are determined under the given conditions. In order to compare the accuracy of these results, the quadratic...
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