Specific Exergy Costing Method Research Articles

District heating based on exhaust gas produced from end-of-life tires in Erzincan: Thermoeconomic analysis and optimization

This paper presents the thermoeconomic analysis and optimization of the Erzincan Waste Tire Recycling and Power Plant (EWTRPP) in Turkey and its waste heat-based district heating (DH) system. A thermoeconomical method, namely the specific exergy costing (SPECO), is applied to allocate cost flows through subcomponents of an actual existing plant. Besides, the obtained thermoeconomic results are improved by using an optimization method, namely non-dominant sorting genetic algorithm (NSGA-II), considering the temperature of the exhaust gas discharged to the atmosphere (T25), the thermal conductivity value of the insulation material (ki) and pipe roughness value (s). The energy and exergy efficiencies of the existing plant are found to be 27.37% and 35.57%, respectively, considering the data of the actual plant. Moreover, the energy and exergy efficiencies of the waste heat-based DH system are found to be 43.08% and 55.99%, respectively. The total cost rate of the overall system is deduced 13.98 $/hby means of SPECO method. According to the results of the NSGA-II optimization method, the exergy efficiency and total cost rate of the overall system are evaluated as 6.93% and −2.51 $/h, respectively. Furthermore, it is also proposed that 1304 dwellings can be heated owing to the DH system utilizing the existing exhaust gas.

APPLICATION OF THE H&S MODEL FOR THE ADVANCED EXERGY ANALYSIS OF AN ORGANIC RANKINE CYCLE

In order to carry out the advanced exergy analysis of a system, an exergoeconomic-based approach is required. The Specific Exergy Costing method is chosen for this. Thus, there is a gap in the literature regarding the application of other approaches. An alternative is the H&S Model, which was originally proposed to solve the cost allocation problem in power cycles. Therefore, the objective of the present paper is to verify whether the H&S Model is able to be adapted for the purpose of performing advanced exergy analysis. The power cycle taken as a case study is an organic Rankine cycle, which is fed with waste heat and uses R-245fa as the working fluid. Both conventional and advanced exergy analyses are done for a base case. In addition, a parametric analysis is performed to check the consistency of the H&S Model. Regarding the results of the case study, the conventional exergy analysis indicated that the evaporator should be the priority to improve the cycle. On the other hand, the advanced exergy analysis showed that the greatest amount of the avoidable exergy destruction was also endogenous and associated with the expander. The results also showed that the adaptation of the H&S Model is possible when considering the base case. It has also been shown that such an adaptation is consistent when taking into account the parametric analysis.

Exergoeconomic analysis in a food industry boiler

This study aims to apply the SPECO method in a firetube steam generating unit located in a food industry to measure the cost and to suggest actions that will increase its efficiency. In the current global scenario, researches for alternatives of the cost reduction and increased sustainability are more and more on the agenda in companies. Therefore, the present work develops a study to make possible the energy losses minimization in biomass boilers located in Saudali food industry, Ponte Nova (Minas Gerais, Brazil). The used methodology was developed from the exergoeconomic analysis using the Specific Exergy Costing (SPECO) method. To possibilitate this procedure it was necessary to map all the exergetic flows and to find its thermodynamic values. Regarding the fuel calorific potential, it was necessary the measurement of its average humidity, measured in (25 ± 1%), approximately, in order to obtain a Lower Calorific Power of 15960 kJ.kg-1. The massic and exergy flow rates values were defined using measurement equipments, thermodynamic tables and company’s information. The obtained results for exergetic efficiency, steam cost and fuel cost were, respectively, 51.74%, 0.0446 R$.(kWh)-1 and 0.01490 R$.(kWh)-1. These results evidenced a cost ratio between product and fuel of 1.99, which represents a product cost two times superior to the fuel cost, approximately. It is concluded that SPECO method application in Saudali industry evidenced important and often disregarded points, as the moisture interference in biomass available exergy and great variance between steam and fuel costs.

Assessment of a cogeneration system for ceramic industry by using various exergy based economic approaches

This study presents various exergy based economic analyses of a gas turbine cogeneration system (COGEN) for a ceramic tile plant for five different reference environment temperatures. Specific Exergy Costing (SPECO) method, which uses fuel-product exergy approach and flow costs, and Exergy-Cost-Energy-Mass (EXCEM) method, which considers exergy loss and destruction with cost association, are used. It has been found that the irreversibilities due to chemical combustion reactions, occurring in the combustion chamber (CC) of the gas turbine unit, wall tile (WD) dryer and ground tile dryer (GD), have negative effects for the destructed exergy cost rate of themselves and overall system. In addition, depending on the destructed exergy cost ratio, the exergy based economic factor rates of these components are found to be lower than others. While the increase of the COGEN's and all of its components' destructed exergy cost rates are direct proportionally to the increase in the environment temperature, they are inversely proportional to the exergy based economic factor. As a result of the SPECO method, in the EXCEM method, the exergy cost parameters of the CC are much higher than the other components at all reference environment temperatures because of the high destructed exergy value of the CC. The system needs to be optimized in terms of eliminating the irreversibilities encountered intensively in the components such as CC, WD, GD. Consequently, these results show that the focus should be on the CC first, then on the WD and GD.

Exergo‐economic assessment by a specific exergy costing method for an experimental thermochemical hydrogen production system

In this article, an exergo-economic study of an experimental lab-scale integrated copper-chlorine (Cu-Cl) cycle of hydrogen production is conducted. The analysis is performed based on a specific exergy costing (SPECO) method to determine the influences of various design criteria on the costs and then identify possible improvements for more cost effective approaches. The article includes an exergy analysis, economic study, exergy costing and exergo-economic evaluation. Also, a scale-up analysis is performed to predict the cost of a larger scale facility of 1000 kg per day of hydrogen production. The results of the exergo-economic and scale-up analysis are expected to assist in the design, optimization and improvement of a scaled-up Cu-Cl thermochemical cycle. Furthermore, the results of this study show that for a large-scale Cu-Cl cycle plant with a capacity of 1000 kg/day H2, the cost of hydrogen production, excluding the treatment of side reactions, is predicted at about 3.91 $/kg H2.

THERMOECONOMIC ANALYSIS OF T56 TURBOPROP ENGINE UNDER DIFFERENT LOAD CONDITIONS

In this study, T56 turboprop engine was theoretically modelled for 75% load, 100% load, military (MIL) mode, and Take-off mode conditions. For each load conditions, thermoeconomic analyses of T56 turboprop engine were performed to allocate the unit costs of shaft work and thrust and to determine exergy destruction cost rates for system equipment. In thermoeconomic analyses, Specific Exergy Costing (SPECO) and Modified Productive Structure Analysis (MOPSA) methods were used. MOPSA method gave higher unit cost values for shaft work and thrust compared to SPECO method. As a result, for Take-off mode, the unit cost of shaft work transferred to propeller was determined to be 78.87 $/GJ in SPECO method, while this value was calculated to be 84.68 $/GJ with MOPSA method. The unit cost of negentropy of T56 turboprop engine decreased with increasing in engine load and ranged from 14.98 $/GJ to 11.08 $/GJ. The exergy destruction cost rates obtained with MOPSA method for the system equipment were considerably lower than the results obtained with SPECO method. For instance, in Take-off mode, exergy destruction cost rate of combustion chamber was calculated to be 865.10 $/h in SPECO method, whereas it was calculated to be 247.94 $/h in MOPSA method. The exergoeconomic factor of overall system was determined to be 23.07% in SPECO method, and 54.16% in MOPSA method for Take-off mode

Experimental thermal/economic/exergetic evaluation of hot/cold water production process by thermoelectricity

Although economic analysis of thermoelectric power generator has been carried out extensively by many researchers, economic reports on the reverse application of thermoelectric (heating/cooling) are completely immature. No experimental-data-based economic evaluation has been carried out before for cooling/heating aim of Peltier effect. Obviously, lack of economic analysis results in incorrect or imperfect decision-making on marketing area of any product. This paper focuses on cold and hot water production by thermoelectricity and provides a comprehensive thermal/economic/exergetic evaluation for said application using recently developed SPECO (Specific Exergy Costing) method. The effect of all thermal/flow and electrical parameters are investigated. The formulation/evaluation process of economic factors is explained step by step to make it ease understanding for the future readers. The results showed that, obtaining for example 1 kWh energy in the form of water cooling or heating is much more cheaper if the input power (DC voltage) of any individual thermoelectric is adjusted in lower value. However, it will take more time to obtain 1 kWh cooling/heating energy when the input power is low. Hence, it is recommended to produce the cold/hot water in no-peak water consumption times with lower input power and store it (instead of cold/hot water production with higher input power through shorter time).

A comparative assessment of SPECO and MOPSA on costing of exergy destruction

This paper presents the comparison of specific exergy costing (SPECO) and modified productive structure analysis (MOPSA) method to test their abilities on costing of exergy destruction. MOPSA method is applied to a combined supercritical CO2 regenerative cycle and organic Rankine cycle using zeotropic mixtures for gas turbine waste heat recovery system. The results obtained with applying SPECO method to the system are taken from literature. The exergy destruction cost rate of overall system is obtained to be $86.08/h and $1,113.13/h for MOPSA and SPECO methods, respectively. The exergoeconomic factor of overall system is found to be 31.88% for SPECO method, while this value is found to be 85.82% for MOPSA method. The obtained results with applying MOPSA method for exergy destruction cost rate are significantly lower and more consistent compared to the results obtained by SPECO method.

A comparative assessment of SPECO and MOPSA on costing of exergy destruction

This paper presents the comparison of specific exergy costing (SPECO) and modified productive structure analysis (MOPSA) method to test their abilities on costing of exergy destruction. MOPSA method is applied to a combined supercritical CO2 regenerative cycle and organic Rankine cycle using zeotropic mixtures for gas turbine waste heat recovery system. The results obtained with applying SPECO method to the system are taken from literature. The exergy destruction cost rate of overall system is obtained to be $86.08/h and $1,113.13/h for MOPSA and SPECO methods, respectively. The exergoeconomic factor of overall system is found to be 31.88% for SPECO method, while this value is found to be 85.82% for MOPSA method. The obtained results with applying MOPSA method for exergy destruction cost rate are significantly lower and more consistent compared to the results obtained by SPECO method.

Exergoeconomic Performance Assessment of a Sulfuric Acid Production Unit Using the Specific Exergy Costing Method

In this work, an industrial sulfuric acid production unit was evaluated using exergetic and exergoeconomic analysis to determine possible improvements in its efficiency and cost effectiveness. The exergoeconomic evaluation was performed by Specific exergy costing method (SPECO). The case study process is the production of sulfuric acid from liquid sulfur by a double absorption contact. The exergy efficiency, exergy losses and exergoeconomic performance of each component in the overall plant were calculated and analyzed. The exergetic analysis, on the studied process, identifies the location, magnitude, and sources of thermodynamic inefficiencies. The obtained results indicated that the largest exergy destruction took place in the combustion stage, representing a 67 % of the total exergy losses. The exergy efficiency of the unit was around 44.7 %. Through the exergoeconomic analysis, the selling price of the produced H2SO4 as well as the total investment cost were estimated and the exergoeconomic factor of each component was quantified. The highest exergoeconomic factor, of 86 %, was observed in the recovery boiler, meaning that reducing the equipment cost of the studied process is of high importance to reduce the final product of the overall system. On the other hand, the combustion oven showed the lowest exergoeconomic factor, of 1.22 %, implying that improving its thermodynamic efficiency would be compulsory for that component.

Exergoeconomic analysis and optimization of a hybrid system based on multi-objective generation system in Iran: a case study

The present work aims to study a multi-objective generation system based on renewable solar and wind energy that has been selected according to the climatic conditions of the area under study, i.e. Bandar Abbas, Iran. In general, the system includes six different sections such as solar cycle, single effect absorption chiller, Rankine cycle with ammonia–water fluid, wind turbine, electrolyzer, and multi-stage flushing desalination. First, the system is investigated in terms of thermodynamic and exergy principles. Then, exergoeconomic analysis with specific exergy costing method (SPECO) is carried out based on the concepts of product, fuel, and cost balancing. The sensitivity analysis investigates the effect of decision parameters on energy and exergy efficiencies. Finally, single-objective optimization is analyzed using conjugate method and the multi-objective optimization is analyzed using genetic algorithm. Results show that, based on multi-objective optimization, isentropic efficiency of turbine is 81%, isentropic efficiency of pump is 77%, pressure ratio of Rankine cycle is 40.32, solar cycle mass flow is 0.8 k/s, outlet temperature of boiler is 113.62°C, exergy efficiency is 32.88%, and operating cost rate is 8.45 dollars per hour. Using multi-objective optimization, operating cost rate decreases by 22.6% and exergy efficiency increases by about 5.31%.

Exergoeconomic Analysis for a Two-Shaft Industrial Gas Turbine Engine

Abstract In this work, the performance of a two-shaft industrial gas turbine engine inspired by SGT-750, one of best technology at Siemens, is analyzed thermodynamically and economically. The modelling and analyzing process for the proposed system was executed through a software package called IPSEpro and validated with manufacturers’ published data. Exergy analysis, based thermodynamics laws with mass conservation, provides valuable information about locations, magnitudes and types of wastes energy in the thermal systems. Exergoeconomic analysis, the amalgamation of exergy with economics, is useful tool to appraise the gas turbine engine cost-effectiveness. The Specific Exergy Costing method is selected in exergoeconomic evaluation because it is the most widely used reported in the literature and provides reliable results. The performance of a gas turbine engine was investigated for different load variation and climatic conditions. The result shows that the main source of irreversibilities take place in the combustion chamber, compressor and high-pressure turbine, respectively, which constitute to about 96 % of total exergy destruction. The exergetic efficiency and exergy loss rate of the proposed system are about 38.4% and 11.8% respectively. The combustion chamber has the highest value of cost (1312.9 $/h) among other components and the source losses may attribute to the component performance. The production cost of the gas turbine engine based on exergoeconomic evaluation is 12.1 US$/GJ.

Thermal and exergoeconomic analysis of a novel solar driven combined power and ejector refrigeration (CPER) system

In the present study, a novel solar driven combined power and ejector refrigeration system (CPER) of 50 kW power capacity composed of an ORC (organic Rankine cycle) and an ejector refrigeration system is investigated. Solar driven CPER system is composed of two main cycles: collector cycle and refrigeration cycle. The collector cycle is made of a U-tube ETC and circulation pump and the ejector refrigeration cycle consists of generator, turbine, ejector, heat exchanger, condenser, evaporator, expansion valve, and pump. Thermodynamic performance of the proposed CPER system is evaluated and a thermo-economic analysis is conducted using the SPECO (specific exergy costing) method. A parametric study showed the effects of condenser temperature, evaporator temperature, generator pressure, turbine back pressure and turbine extraction ratio. The genetic algorithm optimization analysis is conducted which shows 25.5% improvement in thermal energy, 21.27% in exergy efficiency, and 7.76% reduction in the total cost of the CPER system. The results reveal that the performance of the CPER system is considerably improved at higher temperatures of generator and evaporator.

Investigation of the effect of the water phase in the evaporator inlet on economic performance for an Organic Rankine Cycle (ORC) based on industrial data

In this paper, exergoeconomic analysis of an Organic Rankine Cycle (ORC) is presented for a local power plant, located in the southern part of Turkey. Specific Exergy Costing Method (SPECOM) is applied using balance and auxiliary equations for the exergoeconomic analysis. The capital investment cost, operating and maintenance costs, and total investment cost of ORC steam plant are calculated as 7.43 $/h, 6.69 $/h and 14.12 $/h, respectively. The unit exergy cost and exergy cost of the electricity produced by the turbine are found as 11.05 $/GJ and 14.96 $/h, respectively. In order to show the effect of the water phase in the evaporator inlet on economic performance of the system, exergoeconomic factor of the system is calculated for four different water phases. When the evaporator inlet phase is in saturated liquid form, better exergoeconomic performance is observed for the system. The highest exergoeconomic factor is observed in the pump because of the lowest exergy destruction rate and low total investment cost, while the lowest exergoeconomic factor is observed in the evaporator due to the highest exergy destruction rate in the evaporator. Moreover, payback period assessment is calculated as 3.27 years for the ORC power plant.

Exergoeconomic performance assessment of a pilot-scale spray dryer using the specific exergy costing method

In this study, exergoeconomic analysis was performed to evaluate the performance of a pilot scale spray dryer during white cheese powder production by the specific exergy costing (SPECO) method. Drying experiments were carried out at an inlet drying air temperature range of 160–230 °C, an outlet drying air temperature range of 60–100 °C and an atomisation pressure range of 294.2–588.4 kPa. The components of drying system were separately analysed and the effects of operating conditions on system components and the overall system were discussed. Improvements for the drying cabinet should be focused on for process optimisation, whereas structural improvements of the atomiser should strongly be considered for reducing investment costs. Furthermore, investment costs for the feed pump used in the drying system should be decreased or the feed pump should be replaced with a cheaper one. While results showed high inlet and low outlet air temperatures caused high effectiveness for the overall system performance, the operating costs were the most important variable due to expenses.

Thermodynamic and exergoeconomic analysis of a cement plant: Part II – Application

This paper is Part 2 of the study on the thermodynamic and exergoeconomic analysis of a cement plant. In Part 1, thermodynamic and exergoeconomic formulations and procedure for such a comprehensive analysis are provided while this paper provides an application of the developed formulation that considers an actual cement plant located in Gaziantep, Turkey. The overall energy and exergy efficiencies of the plant is found to be 59.37% and 38.99% respectively. The exergy destructions, exergetic cost allocations, and various exergoeconomic performance parameters are determined by using the exergoeconomic analysis based on specific exergy costing method (SPECO) for the entire plant and its components. The specific unit exergetic cost of the farine, clinker and cement produced by the cement plant are calculated to be 43.77USD/GJ, 133.72USD/GJ and 180.5USD/GJ respectively. The specific manufacturing costs of farine, clinker and cement are found to be 3.8USD/ton, 33.11USD/ton and 41.84USD/ton respectively.

Exergoeconomic analysis of a district heating system for geothermal energy using specific exergy cost method

This study presents the exergoeconomic analysis and evaluation in order to provide cost based information and suggests possible locations/components in a GDHS (geothermal district heating system) for improving the cost effectiveness. The analysis is based on the SPECO (specific exergy costing) method, and used to calculate exergy-related parameters and display cost flows for all streams and components. As a real case study, the Afyon GDHS in Turkey is considered based on actual operational data. The obtained results show that the unit exergy cost of heat produced by the Afyon GDHS is calculated as average 5624 $/h. The HEX (heat exchanger)-III among all components should be improved quickly due to the high total operating cost rate and relative cost difference. The HEX-I and PM (pump)-V have the highest exergoeconomic factors among all other system components due to the high owning and operating costs of these components. The heat production costs per exergy unit for all the HEXs decrease due to the high exergy destruction cost rate of the system, while the well head temperature and ambient temperature increase. The SPECO method may be used to improve the cost effectiveness according to exergy rates in GDHSs as a thermal system.

Thermoeconomic assessment of a sustainable municipal wastewater treatment system

Abstract This paper presents the thermoeconomic analysis and assessment of a municipal wastewater treatment system. Operation of an existing municipal wastewater treatment plant is described in detail and a thermoeconomical methodology based on exergoeconomic relations and the specific exergy costing (SPECO) method is provided to allocate cost flows through subcomponents of the plant. SPECO method is based on a step by step procedure which begins from identification of energy and exergy values of all states defined in the present system through fuel (F) and product (P) approach and ends at the point of establishing related exergy based cost balance equations together with auxiliary equations. The system treats nearly 222,000 m 3 domestic wastewater per day by using the primary and secondary treatment systems. Activated sludge is digested in the anaerobic digestion reactors to produce biogas with a 60% methane content. For each 1 m 3 biogas produced in the wastewater treatment plant, 68.26 kg of sludge with the dry matter content of 5.0% is digested. The de-watered digested sludge with the dry matter content of 22% is considered as a waste and used for agricultural land applications, currently. The actual exergetic efficiency of the wastewater treatment plant is determined to be 34% which indicates that 66% of the total exergy input to the plant, mainly by sewage and power consumptions, is destroyed. The exergetic cost rate and the specific unit exergetic cost of the treated wastewater at the exit of the WWTP are found to be 62.05 $/h and 3.804 ¢/m 3 , respectively. The corresponding costs are 81.90 $/h and 1.907 ¢/m 3 for digested sludge at the exit of secondary anaerobic digestion reactor and de-watering unit; and 175.9 $/h and 13.48 ¢/m 3 for the biogas produced at the exit of primary and secondary anaerobic digestion reactors, respectively.

Thermodynamic and thermoeconomic analyses of a trigeneration (TRIGEN) system with a gas–diesel engine: Part II – An application

The paper is Part 2 of the study on the thermodynamic and thermoeconomic analyses of trigeneration system with a gas–diesel engine. In Part 1, thermodynamic and thermoeconomic methodologies for such a comprehensive analysis were provided, while this paper applies the developed methodology to an actual TRIGEN system with a rated output of 6.5 MW gas–diesel engine installed in the Eskisehir Industry Estate Zone, Turkey. Energy and exergy efficiencies, equivalent electrical efficiency, the Public Utility Regulatory Policies Act (PURPA) efficiency, fuel energy saving ratio, fuel exergy saving ratio and other thermodynamic performance parameters are determined for the TRIGEN system. The efficiencies of energy, exergy, PURPA and equivalent electrical efficiency of the entire system are found to be 58.97%, 36.13%, 45.7% and 48.53%, respectively. For the whole system and its components, exergetic cost allocations and various exergoeconomic performance parameters are calculated using the exergoeconomic analysis based on specific exergy costing method (SPECO). The specific unit exergetic cost of the net electrical power, heat energy in the Factory Heating Center (FHC) heating, heat energy in the Painting Factory Heating (PFH) and chilled water in the absorption chiller (ACh) produced by the TRIGEN system are obtained to be 45.94 US$/GJ, 29.98 US$/GJ, 42.42 US$/GJ and 167.52 US$/GJ, respectively.