Total Revenue Requirement Research Articles

An innovative approach for utilizing waste heat of a triple-pressure cogeneration combined cycle power plant by employing TRR method and thermodynamic analysis

The aim of this study is to examine the possible locations where heat recovery can occur in a triple-pressure cogeneration combined cycle power plant and calculate the amount of waste heat that can be recovered. To complete this objective, an adjusted cycle layout is created and the energy system is analyzed from both thermodynamic and exergetic viewpoints. Furthermore, the Total Revenue Requirement (TRR) method and thermoeconomic analysis are used to determine the price of products produced. The optimization results are displayed in a Pareto chart diagram, utilizing a new model with two objective functions - power cost and product heat. This method allows for identifying the best operating point for these types of power plants, accounting for electricity and heat prices across various regions. The implications of this study for the energy sector are significant as it highlights how waste heat recovery plays a crucial role in cogeneration combined cycle power plants. By pinpointing potential heat recovery locations and determining how much waste heat can be recovered, valuable insights are gained that can inform both design and operation decisions for these power plants. Additionally, using the TRR method and thermoeconomic analysis provides a comprehensive framework for evaluating the economic feasibility of this type of system.

Comprehensive comparison of small-scale natural gas liquefaction processes using brazed plate heat exchangers

The brazed plate heat exchanger (BPHE) has some advantages over the plate-fin heat exchanger (PFHE) when used in natural gas liquefaction processes, such as the convenient installation and transportation, as well as the high tolerance of carbon dioxide (CO2) impurities. However, the BPHEs with only two channels cannot be applied directly in the conventional liquefaction processes which are designed for multi-stream heat exchangers. Therefore, the liquefaction processes using BPHEs are different from the conventional PFHE processes. In this paper, four different liquefaction processes using BPHEs are optimized and comprehensively compared under respective optimal conditions. The processes are compared with respect to energy consumption, economic performance, and robustness. The genetic algorithm (GA) is applied as the optimization method and the total revenue requirement (TRR) method is adopted in the economic analysis. The results show that the modified single mixed refrigerant (MSMR) process with part of the refrigerant flowing back to the compressor at low temperatures has the lowest specific energy consumption but the worst robustness of the four processes. The MSMR with fully utilization of cold capacity of the refrigerant shows a satisfying robustness and the best economic performance. The research in this paper is helpful for the application of BPHEs in natural gas liquefaction processes.

Heating and cooling of residential annual application using DMS transcritical CO2 reversible system and traditional solutions: An environment and economic feasibility analysis

Dedicated mechanical subcooling (DMS) transcritical CO2 system for annual residential space heating and cooling is compared with traditional heating/cooling solutions. Environmental and economic analysis model is established to study the system feasibility and performance, and eight typical Chinese cities are selected as the evaluated scenarios. The annual primary energy consumption (PEC) can be considerably reduced by introducing DMS to CO2 system, which is up to 8.65, 15.66, and 55.41% in comparison with baseline (BASE) CO2 system, coal-fired boiler (CFB) + traditional air conditioner (TAC), and direct electric heating (DEH) + TAC system, respectively. The PEC is higher for the severe cold and the cold region, and it is the lowest when small temperature difference fan-coil unit (STD-FCU) is utilized as heating/cooling terminal. The PEC can be reduced by 47.90% when the energy-saving potential for the building envelope is 65%. The gaseous and solid particulate matter emissions can also be significantly decreased by 3.80–9.75% in comparison with BASE CO2 system. The life cycle cost (LCC) performance is improved, and a lowest levelized annual total revenue requirement (TRRL) of 7924.93 CNY is obtained when DMS CO2 system with STD-FCU is used in Guangzhou, which is 4.51–14.04% lower compared with BASE system. CO2 compressor and electricity price have significant impact on the LCC and payback period. DMS CO2 system is a promising solution for annual space heating and cooling with the help of feed-in tariff and CO2 compressor price reduction.

Thermo-economic analysis and optimization of cogeneration systems by considering economic parameters fluctuations

A successful cogeneration system design project needs an estimation of the economical parameters of the project, including capital investment, costs of fuel, expenses in maintenance and operating, and the proper cost for the products. This study describes the economic consideration of the benchmark cogeneration systems, called CGAM system located in the United States. To evaluate the profitability of alternative investments, cost estimation of the capital investment, calculation of the main product cost under the realistic assumption of fuel inflation, electricity inflation, and discount rate are required. Probabilistic analysis of lifetime discounted costs, including fuel and electricity cost changes, are defined by using the Monte-Carlo method for the next 20 years. Also, the total Revenue Requirement (TRR) method is selected as the main evaluation method for the economic model. As the result of calculations, the range of optimized value for inlet and outlet temperature of the combustion chamber, the efficiency of the gas turbine, efficiency and pressure ratio of air compressor in which the plant is economically and functionally in the best operation for the minimum cost of products of the cycle are achieved.

Exergetic and Economic Evaluation of a Transcritical Heat-Driven Compression Refrigeration System with CO2 as the Working Fluid under Hot Climatic Conditions

The purpose of this research is to evaluate a transcritical heat-driven compression refrigeration machine with CO2 as the working fluid from thermodynamic and economic viewpoints. Particular attention was paid to air-conditioning applications under hot climatic conditions. The system was simulated by Aspen HYSYS® (AspenTech, Bedford, MA, USA) and optimized by automation based on a genetic algorithm for achieving the highest exergetic efficiency. In the case of producing only refrigeration, the scenario with the ambient temperature of 35 °C and the evaporation temperature of 5 °C showed the best performance with 4.7% exergetic efficiency, while the exergetic efficiency can be improved to 22% by operating the system at the ambient temperature of 45 °C and the evaporation temperature of 5 °C if the available heating capacity within the gas cooler is utilized (cogeneration operation conditions). Besides, an economic analysis based on the total revenue requirement method was given in detail.

Optimization and advance thermodynamic analysis of dual stage Co2 power cycle combined to gas turbine

This paper presents a thermodynamic and economic modeling of Rankine cycles (RCs) that use waste exhaust energy of a gas turbine in the power plant of Sirri Island in Iran based on energy, exergy and economic concepts. In addition, the exergoeconomic and advanced exergy analyses were performed. This cycle is composed of a supercritical CO2 Rankine and a transcritical CO2 cycle. Two objective functions, including the most rate of net power generation of the Rankine cycle (as a thermodynamic criterion) and the lowest total purchased equipment cost (as an economic criterion), are considered simultaneously. This model is constructed on the basis of the energy, exergy and economic analysis according to the Total Revenue Requirement (TRR) method. After validating the model, the advanced exergy analysis is performed to split exergy destruction rate into endogenous, exogenous, avoidable and unavoidable parts in order to provide detailed information about the potential improvement of the system components. The final results indicate that the net electric power output of the Rankine cycle and the total purchased equipment cost become 2.31 (MW) and 301473 (US$), respectively. Also, the exergy efficiency and the total exergy destruction of the cycle reach 48.4% and 8757.4 (KW), respectively.

Optimum exergoeconomic modeling of novel hybrid desalination system (MEDAD+RO)

The mathematical model for the prediction of a novel hybrid desalination system was presented. The Hybridization of thermal and membrane desalination systems was investigated, and the efficient and appropriate arrangements were introduced. Multi-effect distillation, reverse osmosis and adsorption desalination systems were the major constituents of the novel hybrid system (MEDAD+RO). The thermodynamic and exergetic analysis was done. For economic analysis, the total revenue requirement method was used, and the thermoeconomic analysis was performed. Produced water price resulting from the thermoeconomic analysis, was $ 1.3 per cubic meter. The permeate water production in the novel system has increased to more than twice. The multi-objective optimization with genetic algorithm tool was used to obtain the optimum point of the system. The determination of best tradeoff between the permeate flow rate, price and exergetic destruction of MEDAD+RO, was the final goal of this optimization. In two-objective optimization process, the permeate water flow rate has increased 65.5%, and the price of producing water has reduced 38.4% respect to the base Plant. The optimum layout resulted of there-objective optimization led to the 59.7% increase in water production and 32.3% decrease in water production cost as compared to the first modeling.

A new approach to thermo-economic modeling of adsorption desalination system

The mathematical model for the prediction of an adsorption desalination system (AD) performance with heat and mass recovery was presented. This analysis resulted in the determination of the thermodynamic properties at different points and the specific daily water production value. The computational model based on the mass and heat transfer concept was developed to predict the performance of AD system. Then, the irreversibility analysis was performed, and exergy destruction (considering chemical and physical exergy) was calculated. The exergoeconomic analysis of AD system was implemented. Total revenue requirement method was used in the economic investigation of the scheme. The validated model indicated the water production rate as well as the water production cost. The permeate flow rate in the system was obtained to be 51.3kg/s. The AD system specific daily water production increased up to 11.92. The optimal exergetic efficiency of the system and the cost of water production were calculated to be 5.9% and 0.57 US $ per cubic meter respectively.

Thermo-economic analysis and sizing of the components of an ejector expansion refrigeration system

An ejector expansion refrigeration system (EERS) as an alternative system was proposed to supply the cold water for unit 132 of the second refinery of South Pars, Iran. A thermodynamic model based on energy and exergy analysis and an economic model according to the Total Revenue Requirement (TRR) method have been presented. Sizing of the main components of the system such as evaporator, condenser and ejector device were determined. The effect of the evaporation and condensing temperatures on the cost of the system were analyzed and the optimum values of the condensing and evaporation temperatures were obtained. The optimum pressure drop in suction nozzle was determined. The economic model takes into account the cost of the components, including amortization and maintenance, and the cost of electricity consumption. The results show, the amount of the fuel consumption and the total cost of the EERS are respectively 22% and 15.2% more efficient compared with a basic refrigeration system with an additional heat exchanger (HXRS).

Thermo-economic performance analysis of a gas turbine generator equipped with a pressurized and an atmospheric solid oxide fuel cell

The main objective of this research is to introduce and present two different configurations for hybrid gas turbine-fuel cell systems of direct type and to analyze these systems based on the thermodynamic and thermo-economic models. In the first proposed design, two fuel cells are situated at the upstream of turbine and operate at a specific pressure; while in the second design, one of the cells is transferred to the downstream of turbine, and it works under atmospheric pressure. Also, in the economic analyses performed in this research, a simple economic model and the Total Revenue Requirement model are employed to compute the electricity generation price and the other relevant expenses. The examination of the two proposed systems shows that the hybrid system with one pressurized and one atmospheric fuel cell (the second design) enjoys a higher efficiency and power generation capacity, but at the same time, it has greater exergy destruction and irreversibility rates. The results also indicate that this design generates more pollution compared to the first design. From an economical point of view, the generated electricity price and the purchase, installation and startup costs of both systems are almost the same, and have no significant difference.

An optimal configuration for a solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system based on thermo-economic modelling

The aim of this research is to present an optimal configuration for solid oxide fuel cell-gas turbine hybrid systems based on thermo-economic modelling. To this end, four different designs of direct hybrid systems with pressurized and atmospheric fuel cells have been presented. In the first two designs, one stack fuel cells has been used in the hybrid system, and in the other designs, two stack fuel cells have been utilized. By examining four hybrid system, it was found that hybrid system with one pressurized fuel cell hybrid system is better than the other. The advantages of this system include its lower irreversibility rate, low purchase, low installation and startup costs, and the adequate price of its generated electricity. Results show that the hybrid system with one atmospheric fuel cell has a low electrical efficiency, high irreversibility rate; and also the price of its generated electricity is higher than that of the other proposed systems. Conversely, the hybrid systems with two fuel cells, in spite of enjoying a high efficiency, are not cost-effective and economical. The findings indicate that the total efficiency of 64% and electrical efficiency of 51% was achieved for optimal hybrid system. Also, the thermo-economic analyses show that the generated electricity price is about USD 11.6 cents/kWh based on the Lazareto's model and USD 18.5 cents/kWh based on the total revenue requirement model. The purchase, installation and startup cost of this hybrid system is about $1692/kW; which is almost twice the cost of a gas turbine unit.

Exergoeconomic analysis and multi-objective Pareto optimization of the C3MR liquefaction process

Over the past decades, increasing attention is paid to optimal design and operation of energy intensive industries. A HYSYS simulated model is developed for a propane mixed refrigerant process. Synthesis of pinch and exergy analysis is employed to find the high value of exergetic efficiency. Exergoeconomic analysis also is carried out using the total revenue requirement method. Then a coded genetic algorithm from Matlab software is linked to HYSYS software to optimize the propane mixed refrigerant process. Optimization of the aforementioned system is performed for two singular objective functions. One of the objective functions can minimize the unit cost of exergy, and the other one can maximize exergetic efficiency of the system. In addition, a multi objective function is employed for finding the optimum point in terms of both high exergy efficiency and low total product cost. Results of exergy and exergoeconomic analyses for all the main streams and equipment are presented, and optimization results are compared with corresponding features of the base case design. In the end, sensitivity analysis is employed to examine variation of compressor pressure ratio in terms of total product cost of the system.

Sequential supplementary firing in natural gas combined cycle with carbon capture: A technology option for Mexico for low-carbon electricity generation and CO2 enhanced oil recovery

Combined cycle gas turbine power plants with sequential supplementary firing in the heat recovery steam generator could be an attractive alternative for markets with access to competitive natural gas prices, with an emphasis on capital cost reduction, and where supply of carbon dioxide for Enhanced Oil Recovery (EOR) is important. Sequential combustion makes use of the excess oxygen in gas turbine exhaust gas to generate additional CO2, but, unlike in conventional supplementary firing, allows keeping gas temperatures in the heat recovery steam generator below 820°C, avoiding a step change in capital costs. It marginally decreases relative energy requirements for solvent regeneration and amine degradation. Power plant models integrated with capture and compression process models of Sequential Supplementary Firing Combined Cycle (SSFCC) gas-fired units show that the efficiency penalty is 8.2% points LHV compared to a conventional natural gas combined cycle power plant with the same capture technology. The marginal thermal efficiency of natural gas firing in the heat recovery steam generator can increase with supercritical steam generation to reduce the efficiency penalty to 5.7% points LHV. Although the efficiency is lower than the conventional configuration, the increment in the power output of the combined steam cycle leads a reduction of the number of gas turbines, at a similar power output to that of a conventional natural gas combined cycle. This has a positive impact on the number of absorbers and the capital costs of the post combustion capture plant by reducing the total volume of flue gas by half on a normalised basis. The relative reduction of overall capital costs is, respectively, 15.3% and 9.1% for the subcritical and the supercritical combined cycle configurations with capture compared to a conventional configuration. For a gas price of $2/MMBTU, the Total Revenue Requirement (TRR) – a metric combining levelised cost of electricity and revenue from EOR – of subcritical and supercritical sequential supplementary firing is consistently lower than that of a conventional NGCC by, respectively, 2.2 and 5.7 $/MWh at 0 $/t CO2 and by 4.9 and 6.7 $/MWh at $50/t CO2. At a gas price of $4/MMBTU and $6/MMBTU, the TRR of a subcritical configuration is consistently lower for any carbon selling price higher than 2.5 $/t CO2 and 37 $/t CO2 respectively.

Thermoeconomic analysis of a building heating system

An analysis of a high-temperature circuit of a building energy system is applied with respect to the thermodynamic- and thermoeconomic point of view. The building energy system is supplied by a micro CHP unit and two boilers in parallel. Following the second law of thermodynamics, in the thermodynamic analysis parameters can be found, which affect the magnitude of thermodynamic inefficiencies. The thermoeconomic analysis combines thermodynamic analysis with economic aspects to identify factors involved in the generation of energy costs. The used economic model is based on the Total Revenue Requirement method. As input for the analysis, data from a model of the energy system is used. To capture dynamic effects of the energy system, the system is modelled and simulated with the help of the object-oriented modelling language Modelica. The results of the simulation are afterwards analysed with the help of an evaluation tool implemented in MatLab. Highest inefficiencies and costs are related to the processes in which natural gas is burned, hence in the CHP unit and boilers. Furthermore, the charging and discharging cycles of the heat storage tank and the heat consumption units cause high inefficiencies and costs. The presented analysis can be extended to other energy systems.

Exergy and Thermoeconomic Analysis for an Underground Train Station Air-Conditioning Cooling System

The necessity of air-conditioning causes the enormous energy use of underground train stations. Exergy and thermoeconomic analysis is applied to the annual operation of the air-conditioning system of a large underground train station in Taiwan. The current installation and the monitored data are taken to be the base case, which is then compared to three different optimized designs. The total revenue requirement levelized cost rate and the total exergy destruction rate are used to evaluate the merits. The results show that the cost optimization objective would obtain a lower total revenue requirement levelized cost rate, but at the expense of a higher total exergy destruction rate. Optimization of thermodynamic efficiency, however, leads to a lower total exergy destruction rate, but would increase the total revenue requirement levelized cost rate significantly. It has been shown that multi-objective optimization would result in a small marginal increase in total revenue requirement levelized cost rate, but achieve a significantly lower total exergy destruction rate. Results in terms of the normalized total revenue requirement levelized cost rate and the normalized total exergy destruction rate are also presented. It has been shown by second law analysis when applied to underground train stations that lower annual energy use and lower CO2 emissions can be achieved.

Thermo-economic evaluation of 300 MW class integrated gasification combined cycle with ash free coal (AFC) process

Among the IGCC power plant shut-down causes, fly ash and slag handling part of gasification process account for most of them. Therefore, thermo-economic modeling of 300 MW class IGCC power plant with AFC process to reduce shut-down caused by the gasification process was conducted using the ASPEN Plus®. The system efficiency of the AFC feed IGCC power plant without CO2 capture improved by 3.6% compared to the RC feed IGCC power plant without CO2 capture. On the other hand, the net efficiency of the AFC feed IGCC power plant with CO2 capture was enhanced by 2.5%. The levelized cost of electricity (LCOE) was estimated using the total revenue requirement (TRR) method and the LCOE for AFC feed IGCC power plant without CO2 capture was $ 0.08/kWh, which was less than $ 0.091/kWh for the RC feed IGCC power plant. The LCOE reduction caused by the lowered carrying charge, O&M cost and fuel cost was explained by the improved system efficiency via gross power increase of the AFC process. Finally, the sensitivity analysis was comprehensively made for LCOE of individual IGCC power plant with variation of the economic key parameters of capacity factor, coal price and its escalation rate, variation of equipment cost and CO2 price.

Application of the multi-objective optimization and risk analysis for the sizing of a residential small-scale CCHP system

Multi-objective optimization for sizing of a small-scale combined cooling, heating, and power generation (CCHP) system is performed. In multi-objective optimizing the s CCHP system, the three objective functions including the exergetic efficiency, total levelized cost rate of the system product and the cost rate of environmental are optimized, simultaneously. The environmental impact and thermoeconomic objective are minimized while the exegetic objective is maximized. A comprehensive emission assessment framework suitable for addressing of distributed cogeneration systems is formulated according to an electrical output-based emission factor approach and the environmental impact objective function are defined and expressed in cost terms. The economic analysis is conducted in accordance with the total revenue requirement (TRR) method. The genetic algorithm is applied to find the set of Pareto optimal solutions with respect to the aforementioned objective functions. In the present work, reliability and availability are introduced in the developed models of the system, so that redundancy is embedded in the optimal solution. In this regard, risk analysis is used as a decision-making tool for the selection of the final optimal solution from the obtained Pareto optimal frontier. The sensitivity of the optimal solution respect to variations of input parameters is analyzed.

Exergoeconomic Evaluation of a Modern Ultra-Supercritical Power Plant

In this paper, the exergoeconomic analysis was conducted to an existing ultra-supercritical coal-fired power plant in China to understand the cost-formation process, to evaluate the economic performance of each component and to find possible solutions for more cost-effective designs. The total revenue requirement (TRR) and the specific exergy costing (SPECO) methods were applied for economic analysis and exergy costing, respectively. Quantitative balances of exergy and exergetic costs as well as necessary auxiliary equations for both individual component and the overall system were established. The results show that the exergoeconomic factors of the furnace and heat exchangers at low temperature levels, including air preheater and low-pressure feedwater preheaters, are rather small; while those of other components are relatively large. Moving more heat absorption into furnace to use the effective radiation heat transfer, increasing the air preheating temperature and adding more low pressure feedwater preheaters can be promising solutions for future design.

Modelling and optimisation of a water-ethanol distillation column based on exergoeconomic analysis

Exergoeconomic modelling and optimisation of a water–ethanol distillation column is performed. A model based on energy and exergy analysis is presented here. An economic model of the system is developed according to the Total Revenue Requirement (TRR) method. The objective functions based on the exergoeconomic analysis are developed. The column that includes two main decision variables is considered for optimisation to minimise the cost of the distillate. Water–ethanol distillation is chosen as a case study. Optimisation of the system shows 2.45% improvement in the cost of the distillate (Ethanol). The optimised case induces reflux ratio to be 8.61 and distillate rate as 2284.23 kg/hr.

Exergoeconomic optimization of a trigeneration system for heating, cooling and power production purpose based on TRR method and using evolutionary algorithm

Abstract In the present study, exergoeconomic optimization of a trigeneration system for cooling, heating and power purposes has been carried out. The system is made up of air compressor, combustion chamber, gas turbine, dual pressure heat recovery steam generator and absorption chiller in order to produce cooling, heating and power. The design parameters of this study are selected as: air compressor pressure ratio, gas turbine inlet temperature, pinch point temperatures in dual pressure heat recovery steam generator, pressure of steam that enters the generator of absorption chiller, process steam pressure and evaporator of the absorption chiller chilled water outlet temperature. The economic model used in this research is according to the total revenue requirement (TRR) and the cost of the total system product was defined as our objective function and optimized using a Genetic Algorithm technique. Results of exergoeconomic optimization are compared with corresponding features of the base case system. It has seen that objective function was modified about 15 percent after optimization. Furthermore, a sensitivity analysis has been presented in order to investigate the effects of decision variables on the different objective functions. Decision makers may find the methodology explained in this paper, very useful for optimal comparison and selection of trigeneration systems.