Total Exergy Destruction Cost Research Articles

Energy, exergy, and exergoeconomic analyses of an air source transcritical CO2 heat pump for simultaneous domestic hot water and space heating

The transcritical CO2 heat pump system experiences significant throttling losses in space heating operation due to the higher temperature of returning water. This paper presents an energy, exergy, and exergoeconomic analyses of an air source transcritical CO2 heat pump integrating a tri-partite gas cooler, which is an effective method to match CO2 temperature glide with water for simultaneous domestic hot water and space heating (DHW+SH) production. A pinch point-based numerical model is developed to find the optimal discharge pressure. This validated model is then utilized to investigate the impacts of water inlet temperature and ambient temperature. Two configurations are examined: one with only DHW supply and the other with DHW+SH supply. The results indicate that combining SH with DHW enhances COP by 7.5% with a 7.9% reduction in discharge pressure at 10 °C ambient temperature and 10 °C water inlet temperature. At a water temperature of 10 °C, exergy efficiency improves by 4%. The compressor accounts for 54%–60% of the total exergy loss. The DHW+SH system exhibits an average exergy destruction reduction of 7.6%. With each 5 °C rise in ambient temperature, the DHW+SH system’s total exergy destruction cost rate decreases on average 7.7% compared to the DHW system. Furthermore, the combined exergy destruction cost rate of GC2 and GC3 in DHW+SH is significantly lower (by 48.2%) than only GC3 in DHW. The exergoeconomic factors of the compressor, gas cooler 2, and gas cooler 3 emphasize the need to decrease their costs to enhance cost-effectiveness.

Modeling and Optimization of a Solar-Driven System Coupled with Liquid Dehumidification and Absorption Refrigeration Based on Advanced Exergy and Exergoeconomic Analyses

A novel hybrid system coupled liquid dehumidification with absorption refrigeration driven by solar energy is proposed. Traditional and advanced exergy and exergoeconomic analyses of the system are conducted to ascertain the degree of irreversibility and potential improvement for each component. Based on the advanced exergy and exergoeconomic analyses, the effects of air humidity, segment temperature, and refrigeration temperature on the total exergy destruction and cost rates of the system are obtained. The total avoidable exergy destruction rate, avoidable exergy destruction cost rate, and avoidable investment cost rate of the system are selected as objective functions and optimized by using nondominated sort genetic algorithm-II. The results show that the total exergy destruction rate and the total exergy destruction cost rate reach 262.39 kW and 8.563 $/h, respectively. The generator and regenerator have higher cost rates of the irreversibility overall system, achieving the values 3.536 and 2.430 $/h, respectively. The absorber has the highest investment cost rate in the whole system. The endogenous parts of the exergy destruction and cost rates are much higher than the exogenous parts in the system. Multiobjective optimization results show that optimal values for the total avoidable exergy destruction rate and the exergy destruction cost rate are 50.99 kW and 1.60 $/h, which are 4.15 and 9.14% lower than those calculated by single-objective optimization, respectively. This study provides a potential way to utilize solar energy for dehumidification and refrigeration.

Energy and Thermo-Economic Analysis of Crude Oil Gathering Station and Hydrocarbon Transport

The decline in Indonesia's national crude oil production which is directly proportional to the increase in production operational costs has an impact on reducing state revenues from oil and gas revenue sharing funds. One of the efforts that can be done to eliminate losses from this sector is to conduct energy analysis and exergy analysis to determine the locations where energy and exergy losses occur which are then converted into economic costs in the upstream oil and gas business in the form of losses operating costs. Energy and exergy analysis in this study was conducted at a crude oil collection station and hydrocarbon transportation facility at CPP Blok, Riau, Indonesia. The results showed that the largest energy flow was found in the wash tank, which was 183.546 KW, the shipping pump was 240346.34 KW, and the heater was 398.4 KW. The largest exergy destruction occurred in washing tanks of 73,418 KW, shipping pumps of 0.319 KW and heaters of 0.363 KW, with a total exergy destruction cost of all equipment of 64,243.29 USD/year.

Comparative analysis and multi-criteria optimization of a supercritical recompression CO2 Brayton cycle integrated with thermoelectric modules

Regarding the high expense of the exploiting energy from energy resources, each innovation or modification on the energy systems with the aim of enhancing the efficiency and affordability is so valuable. Along with this fact, in the present work, the effects of employing thermoelectric (TEG) unit in a recompression Brayton cycle ( $${\text{sCO}}_{2}$$ -reB/TEG) are examined. The results of thermodynamic modeling represents that adding the thermoelectric to the system in the s $${\text{CO}}_{2}$$ -reB can improve the net output power about 2.41 kW and increase the first and second law efficiency of s $${\text{CO}}_{2}$$ -reB/TEG system about 1.09% and 1.12% in comparison with s $${\text{CO}}_{2}$$ -reB system. Additionally the exergo-economic analysis for s $${\text{CO}}_{2}$$ -reB/TEG revealed that the reactor and turbine II should be considered more than other elements from exergo-economic point of view since the highest values of $$\dot{Z}_{\rm k} + \dot{C}_{\rm D,k}$$ belong to these components. After identifying the important parameters as well as evaluating system from thermodynamic and economic aspects, a multi-objective optimization is implemented on the $${\text{sCO}}_{2}$$ -reB-TEG system for determining the optimum conditions. Two optimization scenarios are defined using the results of parametric analysis. Multi-objective optimization with first scenario results in total cost rate of 1.6 $ h−1 and total exergy efficiency of 0.5 in minimum temperature, maximum temperature and compression ratio of 36.17 °C, 577.15 °C and 1.6. Furthermore, for optimization based on second scenario results in total exergy destruction cost and exergy destruction rate of 3.04 $ h−1 and 435.85 kW in 48.75 °C, 569.77 °C and 3.44 for minimum temperature, maximum temperature and compression ratio.

Experimental energy, exergy, economic and exergoeconomic analyses of batch-type solar-assisted heat pump dryer

In the present study, a batch-type solar-assisted heat pump dryer (SAHPD) has been developed and experimented in both simple heat pump dryer (HPD) and SAHPD modes for closed system drying of banana chips. The effect of drying time on various energy, exergy, economic and exergoeconomic performance parameters has been investigated. The banana chips have been dried to remove moisture from 83.5% to 11.5% at an air velocity of 1 m/s in the drying chamber. Both energy efficiency and exergy efficiency are found higher for SAHPD. The specific moisture extraction rate is higher for SAHPD as compared to simple HPD. On the basis of economic analysis, the payback period for the SAHPD over the simple HPD is found 46 months. The lowest exergoeconomic factor is for the expansion device in simple HPD and SAHPD with determined values as 0.1395 and 0.2053, respectively. Total exergy destruction cost for simple HPD and SAHPD is 0.1185 $/h and 0.1386 $/h, respectively. It is observed that the most important components that needed to improve based on exergoeconomic factor are expansion device and evaporator. The present study reveals that the SAHPD system is much better than the simple HPD system.

Advanced exergoeconomic evaluation on supercritical carbon dioxide recompression Brayton cycle

This study proposes a comprehensive understanding of the supercritical carbon dioxide recompression Brayton cycle by means of extending and applying the advanced exergoeconomic method as one of the first attempts. The advantages of this advanced exergy-based method are determining the real potential for improvement of each significant component and considering the interactions among system components, which cannot be achieved by using the conventional method. The unavoidable/avoidable and endogenous/exogenous concepts are introduced, and detailed modeling is performed to calculate exergy destruction and investment costs. The results demonstrate that the unavoidable value of each component is higher than the avoidable value for exergy destruction cost (except for high temperature recuperator). Even under the most optimistic scenario, the total exergy destruction cost can only be reduced by 2199.29 $/h (38.86%), and about half of this avoidable variable is exogenous. According to the results of traditional exergoeconomic analysis, the reactor is recommended as the governing component to improve the cost effectiveness of the cycle due mainly to its highest operating cost (5313.39 $/h). On the contrast, the turbine should have the highest improvement priority owing to the highest value of the avoidable operating cost (1390.88 $/h). The findings provide a novel way to guide the design and evaluation of the carbon dioxide Brayton cycle through benefiting from the advanced exergoeconomic analysis.

Modified exergy and modified exergoeconomic analyses of a solar based biomass co-fired cycle with hydrogen production

A solar based biomass co-fired combined cycle with hydrogen production is proposed and assessed with conventional and modified thermodynamic and exergoeconomic analyses. The cycle uses biomass and solar energy as renewable energies along with the fossil fuel natural gas. Hydrogen is produced by the photovoltaic/thermal system and in one option is injected to the combustion chamber of combined cycle to reduce fossil fuel usage and CO2 emissions. Modified analyses are based on avoidable and unavoidable exergy destruction and component investment costs. Although hydrogen injection does not increase efficiencies, it reduces the exergy destruction by 0.24%, the total exergy destruction cost rate by 3.36%, the CO2 discharge rate by 2% and the total unit product cost by 3%. Based on conventional analysis, the gasifier, the post combustion chamber and the combustion chamber are the components with high exergy destructions, while based on modified analysis the combustion chamber, the gas turbine and the air compressor have highest exergy destructions. The components with the highest investment cost rates are shown to be the steam turbine, gas turbine and air compressor by conventional method while with the modified method they are found to be the gas turbine, the air compressor and the steam turbine.

Thermoeconomic analysis of a CO2 compression system using waste heat into the regenerative organic Rankine cycle

The present paper deals with the thermoeconomic analysis of a CO2 compression system using waste heat into the regenerative organic Rankine cycle. The compressor power required for CO2 compression in the Carbon Capture and Storage has been supplied from a regenerative organic Rankine cycle which is used in thermal power plant. By using the turbine power supplied from the heat drawn and waste flue gas and the intercooler heat exchangers, 8% of the CO2 separated from the waste flue gas compressed in the gas compressor. Thermoeconomic analysis of the system is performed by calculating thermodynamic and economic properties of the system. Energy and exergy efficiencies of cycle have been calculated as 17.2% and 51.6%. The average exergetic cost of waste heat flue gas as a fuel input in the integrated to the system is calculated to be 12.34 $/GJ or 947.5 $/h. The unit exergetic cost of electricity from the ORC system is calculated to be 17.47 $/GJ or 0.063 $/kWh. The unit exergetic cost of compressed CO2 gas is calculated to be 84.9 $/GJ or 184.3 $/h at 310 K and 15,244 kPa. The cost of compressed CO2 in the plant is calculated to be 18.36 $ per tonne of CO2. The total exergy destruction cost rate of the plant and the most destructive component of the flue gas heat exchanger is calculated to be 297.8 $/h and 219.1 $/h, respectively.

Parametric study and multi-criteria optimization of total exergetic and cost rates improvement potentials of a new geothermal based quadruple energy system

The current study presents a new designed quadruple energy production system integrated with geothermal energy involving a cascade organic Rankine cycle, liquefied natural gas vaporization process, proton exchange membrane electrolyzer to produce four types of energies, namely electricity power, heating load for vaporizing liquefied natural gas, cooling effect and hydrogen. Besides conventional analyses, advanced thermodynamic and thermoeconomic analyses are conducted to determine the irreversibilities and related cost rates within the components of the desired system to find the amount of total avoidable exergy destruction rate, and total avoidable cost rates. Moreover, the effect of substantial design parameters namely, upper cycle mass flow rate, liquefied natural gas mass flow rate, geothermal mass flow rate, turbine 1 inlet pressure, liquefied natural gas pressure, geothermal pressure and condenser 1 outlet temperature are evaluated on the total avoidable exergy destruction, total avoidable exergy destruction cost and investment cost rates as well as their subdivisions. Sensitivity studies indicate that geothermal mass flow rate has a drastic positive effect on the total avoidable exergy destruction rate and total exergy destruction cost rate within 137.2% and 119.5%, respectively while condenser 1 outlet temperature improves total avoidable investment cost rate by about 0.05$/h, as compared with other parameters. Finally, Non-dominated Sort Genetic Algorithm-II is applied to achieve the maximum improvement potential for desired system. Optimization results show that total avoidable exergy destruction rate and total avoidable exergy destruction cost rate get 3.27 and 4.9 times, respectively and total avoidable investment cost rate is improved within 17.4% relative to the base point.

Exergy and exergoeconomic analyses of a supercritical CO2 cycle for a cogeneration application

Detailed exergy and exergoeconomic analyses are performed for a combined cogeneration cycle in which the waste heat from a recompression supercritical CO2 Brayton cycle (sCO2) is recovered by a transcritical CO2 cycle (tCO2) for generating electricity. Thermodynamic and exergoeconomic models are developed on the basis of mass and energy conservations, exergy balance and exergy cost equations. Parametric investigations are then conducted to evaluate the influence of key decision variables on the sCO2/tCO2 performance. Finally, the combined cycle is optimized from the viewpoint of exergoeconomics. It is found that, combining the sCO2 with a tCO2 cycle not only enhances the energy and exergy efficiencies of the sCO2, but also improves the cycle exergoeconomic performance. The results show that the most exergy destruction rate takes place in the reactor, and the components of the tCO2 bottoming cycle have less exergy destruction. When the optimization is conducted based on the exergoeconomics, the overall exergoeconomic factor, the total cost rate and the exergy destruction cost rate are 53.52%, 11243.15 $/h and 5225.17 $/h, respectively. The optimization study reveals that an increase in reactor outlet temperature leads to a decrease in total cost rate and total exergy destruction cost rate of the system.

Exergy, economic and environmental impact assessment and optimization of a novel cogeneration system including a gas turbine, a supercritical CO2 and an organic Rankine cycle (GT-HRSG/SCO2)

Exergoeconomic and exergoenvironmental analyses are reported for a novel cogeneration system including a gas turbine, a heat recovery steam generator, a supercritical carbon dioxide recompression Brayton cycle and an organic Rankine cycle. A comprehensive parametric study is carried out to clarify the effects of some decision parameters on the exergoeconomic performance of the proposed system. Also, the payback period is determined for the proposed system. The sum of capital investment cost, total exergy destruction cost and environmental impact cost is considered as an objective function which is optimized with respect to the decision parameters. The variation in overall exergoeconomic factor is determined and its implication to the system design is discussed. It is observed that under the optimized condition the average product unit cost of the system (cost of produced power and steam) is decreased by 0.56$/GJ when compared to the value obtained under a base condition.

An exergoeconomic assessment of waste heat recovery from a Gas Turbine-Modular Helium Reactor using two transcritical CO2 cycles

A comprehensive study is performed on an energy conversion system which combines a gas turbine-modular helium reactor (GT-MHR) and two transcritical CO2 cycles (tCO2). The aim of this study is to assess the energy, exergy and economic behavior of the proposed system, considering five indicators: the energy efficiency, the exergy efficiency, the total exergy destruction cost rate, the overall exergoeconomic factor and the total cost rate. A parametric study is also conducted to evaluate the influence of key decision variables on the GT-MHR/tCO2 performance. Finally, the combined cycle is optimized to minimize the total cost rate. The results show that the energy efficiency of GT-MHR/tCO2 cycle is 7.92% higher than that of the simple GT-MHR cycle at 850°C. The largest exergy destruction rate takes place in the reactor, and after that in the helium turbine and the recuperator. The components in tCO2 cycles have less exergy destruction. When the optimization is conducted based on the exergoeconomics, the overall exergoeconomic factor, the total cost rate and the total exergy destruction cost rate are 55.2%, 20,752$/h and 9292$/h, respectively.

A comparative study on the ammonia–water based bottoming power cycles: The exergoeconomic viewpoint

A comparative exergoeconomic assessment is reported for Ammonia-Water Rankine (AWR) and Ammonia-Water Recuperative Rankine (AWRR) bottoming power cycles. Through investigating temperature distributions of hot and cold fluids and pinch point location in heat exchangers, first energy and exergy analysis is performed and then cost balances and appropriate auxiliary equations are developed for components, so exergoeconomic variables are quantified. A parametric study is also performed to examine the effects on exergoeconomic performance of the cycles, of turbine inlet pressure and ammonia mass fraction in the working fluid. As a result, unit cost of electricity produced by turbine is determined to be 11.87 and 13.85 cent/kWh for the AWR and AWRR systems, respectively. Based on these values it is interesting to note that, unlike the energy and exergy analysis, the exergoeconomic viewpoint prefers the AWR system to AWRR. Also parametric study revealed that ammonia concentration has a great effect on exergoeconomic performance of the both systems. Increasing ammonia mass fraction increases total exergy destruction cost rate as well as unit cost of electricity produced by turbine in the both AWR and AWRR systems. This shows the advantage of using a binary mixture such as ammonia–water as a working fluid in these cycles.

A comparative analysis of rankine and absorption power cycles from exergoeconomic viewpoint

In this paper LiBr–H2O and NH3–H2O absorption power cycles and Rankine cycle which produce 1MW electrical power in same conditions of heat sources are compared from exergoeconomic point of view. Exergoeconomic analysis is performed using the specific exergy costing (SPECO) method. The results show that among these cycles, although the LiBr–H2O cycle has the highest first law efficiency, but unit cost of electricity produced by turbine for LiBr–H2O cycle is more than that for Rankine cycle. This value is lowest for the NH3–H2O cycle. Moreover, the NH3–H2O cycle has the highest and the LiBr–H2O cycle has the lowest exergy destruction cost rate. The generator, the absorber and the boiler in all considered cycles have the maximum value of sum of cost rate associated with capital investment, operating and maintenance, exergy destruction and exergy losses. Therefore, these components should be taken into consideration from exergoeconomic viewpoint. In parametric study, it is observed that in the constant generator temperature, as the generator pressure increases, unit cost of power produced by turbine for LiBr–H2O and Rankine cycles decreases. This value for Rankine cycle is lower than for LiBr–H2O cycle whereas Rankine cycle efficiency is less than the efficiency of LiBr–H2O cycle. Also, in LiBr–H2O cycle, at constant temperature of the generator, the value of exergy destruction cost rate is minimized and exergoeconomic factor is maximized at particular values of generator pressure and the more absorber pressure results the minimum value of total exergy destruction cost rate.