Unit Production Cost Research Articles

Exergoeconomic, exergoenvironmental analysis and multi-objective optimization of a novel combined cooling, heating and power system for liquefied natural gas cold energy recovery

This paper designs and investigates a novel combined cooling, heating, and power (CCHP) system for effectively utilizing liquefied natural gas (LNG) cold energy and waste heat of exhaust gas based on thermodynamic, exergoeconomic and exergoenvironmental analysis. The effects of the mass flow rate of the ORC-I’s working fluid, turbine 1 inlet temperature, compressor and pump outlet pressure and the turbines’ isentropic efficiency on the system performance were investigated. In addition, the non-dominated sorting genetic algorithm II (NSGA-II) and the particle swarm optimization (PSO) were employed to optimize the CCHP system with multiple objectives, respectively, to find the optimal operating conditions of the system. The optimization results showed PSO was superior for the multi-objective optimization of this novel CCHP system compared to NSGA-II, showing the exergy efficiency, product unit cost and product unit environmental impact of 70.20%, 21.50 $/GJ and 57.91 mPts/GJ, respectively.

Superstructure optimization model for design and analysis of CO2-to-fuels strategies

CO2 utilization to fuel production, wherein captured CO2 is used as raw materials and partially replaces the use of fossil fuels, is an effective solution for energy security and global warming. In this study, an optimization-based framework was developed for CO2-to-fuel superstructure to determine the optimal strategies for desired fuels (i.e., methanol (MeOH), Fischer–Tropsch synthesis (FT) fuels, dimethyl ether (DME), and gasoline). The aim of the framework is to address specific problems of minimizing energy consumption, unit production cost, and net CO2 equivalent emission. Thus, we first generated a superstructure of alternative CO2-to-fuel pathways, and each pathway contains a set of carbon conversion and separation technologies toward the final fuel from CO2 feedstock. Subsequently, a process simulation and energy–economic–environmental parameters of possible pathways were generated and further embedded into the optimization model. The optimization results indicate that, among CO2 utilization technologies, direct catalytic hydrogenation is recognized as the most economical and environmentally friendly pathway for MeOH at 3.6 $/GGE (reduced 1.01 kg CO2/GGE), gasoline at 3.71 $/GGE (reduced 1.86 kg CO2/GGE), and DME at 4.46 $/GGE and near-zero-emission. However, FT fuels are not suggested since they consume more energy for a higher production cost and emit 3.22 kg CO2/GGE. Using various process system engineering-centric techniques, this study also determined that H2 feedstock cost, associated with CO2 utilization strategies, is the major economic–environmental factor and investigated the CO2-to-fuel application potential in various market conditions based on regions or time.

The optimal product-line design and incentive mechanism in a supply chain with customer environmental awareness

<p style='text-indent:20px;'>Due to the increasing awareness of sustainable development, the manufacturer's product-line design gets wide attention. Nowadays, the traditional manufacturer that produces non-green products is considering whether to introduce upgraded green products. This paper studies the manufacturer's optimal product-line design considering the quality difference between non-green and green products. Besides, our model also investigates the difference in unit production cost, green research and development (R&D) investment, and market segmentation. The results show that, from the manufacturer's perspective, producing green products is a better choice when non-green products are of low quality. In addition, the retailer is always inclined to sell green products. Further, the consumers' preference for non-green and green products is divided. And the consumer surplus under different product-line designs is analysed. Finally, two contracts are proposed and compared to encourage the manufacturer to produce green products.</p>

Cooperative and noncooperative R&D in duopoly manufacturers with a common supplier

<p style='text-indent:20px;'>We consider the R&D strategy of firms under competitive environments from the supply chain perspective. Specifically, we investigate a supply chain consisting of one upstream component supplier and two downstream manufacturers, who however are the Stackelberg leader(s). At the early stage (<i>R</i>&<i>D</i> <i>stage</i>), the two manufacturers decide on whether to cooperate or not in the R&D activities and how much to invest in R&D accordingly. At the late stage (<i>market stage</i>), the component supplier decides on the uniform wholesale price and the manufacturers decide on the production quantities. Our main findings include: (ⅰ) Cooperative R&D strategy will be adopted when the technology spillover effect is either too large or too small and in contrast non-cooperative strategy will be accepted when the spillover effect is moderate. However, the underlying driving forces for coordination are different when the spillover effect is small or large, i.e., <i>cost reduction effect</i> and <i>sales increasing effect</i>. (ⅱ) Cooperative R&D could increase the social welfare when both the technology spillover effect and the (initial) unit production cost are high. (ⅲ) As the equilibrium under the cooperative R&D strategy is unstable, we give a coordination mechanism, to guarantee the stability of cooperative R&D investments.</p>

Концентраторний фотоенергетичний модуль на основі кремнієвих фотоперетворювачів

The task of reducing the cost of an energy unit obtained by the photovoltaic method remains relevant. One of the effective methods of reducing the production cost of energy units is to use installations that concentrate solar irradiation. In this study, the authors develop design and technological solutions and use silicon backside contact photoconverters with a rear placement of the collector p–n-junction and both contact electrodes to make a solar photovoltaic module of the required size. This photovoltaic module with front surface dimensions of 0.42×0.05 m2 is intended for use in a solar power plant with the parabola-cylindrical concentrator. The first stage of experimental and theoretical research of photovoltaic characteristics of the solar module is carried out in the conditions of unconcentrated and weakly concentrated solar irradiation. It is established that the used solar photoconverters have fairly low values of the series resistance and the solar photovoltaic module has a sufficiently high efficiency of the photovoltaic conversion. It is planned to further test the developed solar module in the conditions of natural sunlight irradiation concentrated 20-fold, which will allow determining the ways to improve its characteristics.

Концентраторний фотоенергетичний модуль на основі кремнієвих фотоперетворювачів

The task of reducing the cost of an energy unit obtained by the photovoltaic method remains relevant. One of the effective methods of reducing the production cost of energy units is to use installations that concentrate solar irradiation. In this study, the authors develop design and technological solutions and use silicon backside contact photoconverters with a rear placement of the collector p–n-junction and both contact electrodes to make a solar photovoltaic module of the required size. This photovoltaic module with front surface dimensions of 0.42×0.05 m2 is intended for use in a solar power plant with the parabola-cylindrical concentrator. The first stage of experimental and theoretical research of photovoltaic characteristics of the solar module is carried out in the conditions of unconcentrated and weakly concentrated solar irradiation. It is established that the used solar photoconverters have fairly low values of the series resistance and the solar photovoltaic module has a sufficiently high efficiency of the photovoltaic conversion. It is planned to further test the developed solar module in the conditions of natural sunlight irradiation concentrated 20-fold, which will allow determining the ways to improve its characteristics.

Integrative approach of thermoeconomics to obtain unit cost of products in power systems

Integrative approach of thermoeconomics to obtain unit cost of products in power systems

Technique for Multi-Pass Turning Optimization Based on Gaussian Quantum-Behaved Bat Algorithm

The multi-pass turning operation is one of the most commonly used machining methods in manufacturing field. The main objective of this operation is to minimize the unit production cost. This paper proposes a Gaussian quantum-behaved bat algorithm (GQBA) to solve the problem of multi-pass turning operation. The proposed algorithm mainly includes the following two improvements. The first improvement is to incorporate the current optimal positions of quantum bats and the global best position into the stochastic attractor to facilitate population diversification. The second improvement is to use a Gaussian distribution instead of the uniform distribution to update the positions of the quantum-behaved bats, thus performing a more accurate search and avoiding premature convergence. The performance of the presented GQBA is demonstrated through numerical benchmark functions and a multi-pass turning operation problem. Thirteen classical benchmark functions are utilized in the comparison experiments, and the experimental results for accuracy and convergence speed demonstrate that, in most cases, the GQBA can provide a better search capability than other algorithms. Furthermore, GQBA is applied to an optimization problem for multi-pass turning, which is designed to minimize the production cost while considering many practical machining constraints in the machining process. The experimental results indicate that the GQBA outperforms other comparison algorithms in terms of cost reduction, which proves the effectiveness of the GQBA.

Custos de produção e avaliação de terras: Um estudo de caso de Polatlı, Turquia

ABSTRACT: In this study, the share of land rent in the fixed costs of wheat production was examined, and the aim of the study was to find land values using cost tables. To this purpose, we showed the effect of these on land values from the difference between field rents and net income. The study covered the district of Polatlı in Ankara province. Data on wheat production in Polatlı in 2017 was collected from six villages and 37 farms by means of a questionnaire. In selecting the farms, the ability to determine the land rent was taken into account as a selection criterion. The farms examined used on average per hectare, 11.9 hours of labor, 7.7 hours of draft power, 354.3 kg of fertilizer, 205.5 kg of seed, and 1.5 liters of agricultural chemicals. The average wheat production cost per hectare was $865.42; the average unit production cost was $0.23, and the production value was reported to be $1012.40/da. In this study, the land rent was of $225.40, and the net income from the land was reported to be $372.42. It was reported an evaluation performed using the taxation tables that land values according to rental incomes were $4508.80/ha, and $7448.40 when the land was worked by the landowner. Land rent constituted 26.05% of total production costs, and were equivalent to 22.26% of production value. When crop prices increased by 1%, income from the land increased by 4.49%.

ГЛОКАЛІЗАЦІЯ ЯК ВИЗНАЧАЛЬНИЙ ЧИННИК ОРГАНІЗАЦІЇ ЗОВНІШНЬОЕКОНОМІЧНОЇ ДІЯЛЬНОСТІ В УМОВАХ ЄВРОІНТЕГРАЦІЇ

In the conditions of European integration, economic organizations are forced to solve a kind of dilemma: to perceive the international business environment as a homogeneous globalized system that needs a unified strategy of behavior, or, nevertheless, to consider it as a heterogeneous set of conditionally separated spaces, which are represented by integration entities at the region or even local market levels, the conquest of which is possible if differentiated approaches are used. Approaches to the interpretation of the term "glocalization" meaning, which denotes the contradictory spatio-temporal configuration of the international business environment, which is formed under the influence of alternating modes of heterogeneity growth and smoothing, overlapping of globalization and regional integration factors have been systematized in the article. The prerequisites and driving forces of glocalization have been considered as a kind of synthesis of the processes of globalization and localization, which makes it possible at the same time to cultivate the territorial specificity of a certain activity, with an orientation towards the minimization of circulation costs, and the emergence of business interests in overcoming geographical distance, with an orientation towards the minimization of unit production costs of products. It has been proved that in the conditions of hypercoherence of the world economy system, in order to adapt to the turbulent environment and ensure the proper efficiency of foreign economic operations in it, domestic enterprises are forced to develop a global strategy of foreign economic activity (FEA), a feature of which is the combination (on the basis of self-organization) of global and multinational strategy features with the aim of achieving a set of synergistic effects. The glocal strategy involves the development of an algorithm of actions that allows simultaneously generating advantages of scale, uniformity of products and price competition in a certain period of time (globalization) and differentiation of the product offer in spatially limited sales markets (localization). The term "glocal management of foreign economic activity" has been suggested to denote the process of applying management concepts and tools for regulating the behavior of business entities in a glocalized business environment. Based on the results of the research, structural and logical schemes for the formation of a glocalized business environment and the behavior of foreign trade entities in it have been developed.

Enhancement of lipid yield in <em>Chlorella</em> sp. under different stress conditions for the production of biodiesel

Microalgae derived bio-lipids can be potentially converted to biofuel using appropriate technologies. However, optimum conditions for enhancing the growth of microalgae often lead to relatively low accumulation of bio-lipids. Alternatively, stress conditions favor the storage of lipids despite the low biomass yield. For commercial production of microalgae derived biofuel, the unit cost of production of biodiesel should be lower than that of petro diesel. The aim of the present study was to enhance the lipid yield of <em>Chlorella</em> sp. by introducing various stress conditions such as nitrogen deficiency, zinc deficiency and excessive salinity in the growth media. Conventional Bold’s Basal Media (BBM) was used as the culture media in all the experimental conditions. Five treatments were used namely; normal Bold’s basal media, three times concentration enhanced Bold’s basal media, Nitrogen deficient media, Zinc deficient media and Salinity stress media. Light intensity was kept constant in all the experimental conditions. Air mixing was provided using spargers in all test conditions to keep the microalgae cultures in suspension. All the reactors were maintained in similar growth conditions in the first phase and the stress conditions were introduced in the second phase after 7 days. The microalgae biomass was harvested on 4th, 8th, 11th, 14th and 17th day of cultivation for the determination of lipids. A Chloroform: Methanol mixture with 1:1 ratio was used to extract lipids from dried biomass using Soxhlet extractor. A considerable increase in the lipid content was observed in all the test conditions compared to control samples (highest was 16.9%). Highest lipid content of 23.3% was observed in Zn stressed conditions. However, in terms of lipid productivity, salinity stress treatment produced the highest average lipid productivity of 0.008±0.005 mgL^-1d^-1. After certain period of time (14th day), lipid content of stressed samples decreased. Oleic acid and linoleic acid were found to be abundant in all of the treatments. The study suggests that imposing stressful conditions can result in a higher amount of lipid yield from the algae biomass with a higher rate of productivity that contains important fatty acids which can be a feasible opening for biofuel production.

On the optimal solution of a distributionally robust multi-product newsvendor problem

This paper derives the optimal solution for a distributionally robust multi-product newsvendor problem, in which different products are produced under a capacity constraint, while only the mean and variance of the product demand are known. The problem aims to find a capacity allocation scheme to minimize the system cost of the worst-case among all possible demand distributions. When the total capacity is among certain ranges, the optimal solution has a closed-form. For other ranges, the optimal solution can be derived by solving one equation. The solution shows that there exist a number of threshold values for the capacity, below which some products are neglected (allocated with zero capacity). Besides, in the optimal solution, which products are prioritized for production is determined by the order of an index measured by the unit production cost, unit shortage cost, demand mean, and demand variance. For a special case where the cost structures for different products are identical, a closed-form solution is derived for any total capacity value. For this special case, the index order is simply determined by the coefficient of variation of each product demand. Sensitivity analysis shows that when the capacity is abundant, a larger demand variability of one product may cause a higher production quantity for this product; while if the capacity is tight, a larger demand variability cause a lower production quantity. For a set of test problems, the performance of the robust optimization solution is quite close to that of the stochastic optimization solution.

Comparison of different cereal grains for hydroponic fodder production in locally constructed polyhouse at Khumaltar, Lalitpur, Nepal

Hydroponic fodder production technology involves an intensive method of quality fodder production in less space and in a shorter duration. An experiment was conducted to compare the different cereal grains under hydroponic fodder production for the fodder yield, fodder quality, and per unit production cost in a locally constructed polyhouse. Maize (Zea mays L.), oat (Avena sativa L.) and wheat (Triticum aestivum L.) were evaluated as the treatments. The experiment was carried out in Completely Randomized Design (CRD) with 12 replications at National Pasture and Fodder Research Program in July 2017 and July 2018. The observations were taken on plant morphological characters, fodder yield (including root mat), fodder nutrient composition and expenses in variable costs. The results of the study showed that the fodder yield varied significantly (P&lt;0.05) for different cereal grains. The hydroponic fodder yields from each kg grain were recorded higher in fodder oat (7.96 kg) compared to wheat (6.76 kg) and maize (5.32 kg). Similarly, the crude protein (CP) content of the fodder was higher in wheat (16.16%) compared to oat (13.96%) and maize (12.51%). The cost of hydroponic maize, oat and wheat fodder production were obtained as recorded NPR 20.64, 24.67 and 18.76 per kg, respectively.

A prediction-based supply chain recovery strategy under disruption risks

ABSTRACT This paper proposes a prediction-based product change recovery strategy for the SC (supply chain) under long-term disruptions. A real-world case composed of multi-period planning and dynamic customer demand is considered. First, to forecast dynamic customer demand, a data-based demand predictive method with feedback errors is designed. Second, to schedule procurement and production in advance, based on the predicted demand, the selection of the supply portfolio is transformed into a bi-objective mixed integer programming problem incorporating product change. Furthermore, goods allocation and customer order fulfillment strategy is also designed to finish the transportation of goods and delivery of customer orders. To systematically synthesise and address the problems aforementioned, a three-stage heuristic method is further developed. Finally, a case study is presented to substantiate the reliability of the proposed strategy via an actual SC model of Dongsheng Electronics Co., Ltd. Based on the results obtained after one month, the proposed disruption recovery strategy can reduce the unit product cost and improve the service level, which outperforms the original method adopted by Dongsheng. Additionally, sensitivity analysis of unit product change cost is conducted to reveal the effect of different unit product change costs on SC performance.

Multi-mode and exergoeconomic analysis of a novel combined cooling, heating, and power system applied in the geothermal field

The exploitation and utilization of geothermal resources contribute to alleviating energy crisis and reducing environmental pollution caused by the use of fossil fuels. The energy systems driven by low-grade geothermal heat sources also have the potential for energy-saving and emission reduction. Among all kinds of energy systems, multi-mode systems with characteristics of various operation modes and flexible energy output have been widely concerned. In this work, a multi-mode CCHP system with a novel structure is proposed and driven by a closed type of geothermal heat source. The proposed parallel system is composed of a vapor compression heat pump cycle, an organic Rankine cycle, and a vapor compression refrigeration cycle. The exergy efficiency and total product unit cost are selected as objective functions in multi-objective optimization processes to characterize system thermodynamic and exergoeconomic performances, respectively. The proposed system can operate in seven different modes to realize the conversion of power, heating, and cooling capacity output. The effects of main parameters, including evaporation pressure, condensing temperature, split ratio, etc, on system performances were studied. Results found that the coupling evaporator had the highest exergy destruction rate while the component turbine showed the largest capital cost. From the viewpoint of exergoeconomic performance, the turbine and coupling condenser were the most two important components. After that, the multi-objective optimization results revealed the limits of comprehensive system performance under such closed heat source conditions. Finally, the adjustable analysis found the performance range of the proposed system regulating the seven different operation modes. The exergy efficiency and total product unit cost fluctuated in the ranges of 18.68–52.64 % and 9.56–14.93 $/GJ, respectively.

Design Parameters of a Direct Contact Membrane Distillation and a Case Study of Its Applicability to Low-Grade Waste Energy.

In the design of membrane distillation systems, the effect of different heat transfer coefficient models on the transmembrane flux seems to have been overlooked thus far. Interestingly, the range of discrepancy in the results of the transmembrane flux is wide, especially in the laminar flow region, where MD is often operated. This can be inferred by studying the design and parameters of the direct contact membrane distillation system. In this study, the physical and physiochemical properties that affect the design of MD are comprehensively reviewed, and based on the reviewed parameters, an MD design algorithm is developed. In addition, a cost analysis of the designed MD process for low-grade-energy fluids is conducted. As a result, a total unit product cost of USD 1.59/m3, 2.69/m3, and 15.36/m3 are obtained for the feed velocities of 0.25, 1 and 2.5 m/s, respectively. Among the design parameters, the membrane thickness and velocity are found to be the most influential.

Thermodynamic, environmental, and exergoeconomic feasibility analyses and optimization of biomass gasifier-solid oxide fuel cell boosting a doable-flash binary geothermal cycle; a novel trigeneration plant

Heat recovery boosting applications, especially polygeneration, provide an efficacious effort toward sustainable energy supply, air pollution control, and financial saving. Among new technologies, solid oxide fuel cells are able to effectively operate benefiting from high-temperature syngas output to boost the applicability of combined cycles. Respecting this manner and embracing a renewable energy resource, i.e., biomass fuel, a biomass Gasifier-Solid oxide fuel cell is devised in this paper; its waste heat is recovered by a doable-flash binary geothermal power plant for better operation. Accordingly, a thermal-based desalination, namely humidification dehumidification desalination, and a domestic water heater are joint to the geothermal cycle resulting in a novel trigeneration application. The possibility is measured by thermodynamic, environmental and exergoeconomic tools; a comprehensive sensitivity analysis is applied together with a multi-objective grey wolf optimization in three different optimization scenarios. Considering eight decision variables for the sensitivity analysis and optimization, the optimization scenarios comprise exergetic efficiency/sum unit cost of products, exergetic efficiency/levelized total emission, and exergetic efficiency/hot water production. Here, the last scenario possesses the best optimum exergetic efficiency of 64.49%; the optimum sum unit cost of product, levelized total emission, and heating production are forecasted at 4.94 $/GJ, 0.124 ton/MWh, and 6549.77 kW, respectively.

A new combined power and dual ejector refrigeration system using zeotropic mixtures with composition adjustable driven by geothermal resource: An exergoeconomic performance evaluation

In this study, a novel geothermal-driven combined power and dual ejector refrigeration (CPDER) system using the zeotropic mixture as the working fluid with composition adjustable is presented, investigated, and assessed from an exergoeconomic viewpoint. The proposed system includes two ejector refrigeration subsystems connected in parallel mode. The zeotropic mixture is distributed into these subsystems through a vapor-liquid separator with various compositions. To represent the superiority of the proposed CPDER system compared to the conventional ones, a comprehensive parametric perusal is conducted. The results reveal that the mixture composition and outlet pressure of the turbine have the biggest impact on the total exergy destruction and the net power output, while the outlet temperature of the evaporator has the biggest effect on the refrigeration capacity. Furthermore, optimal operating condition is found through a tri-objective optimization process where energy efficiency, exergy efficiency, and overall unit cost of products are chosen as objective functions. The optimization results detect that for the proposed CPDER system, the energy efficiency and exergy efficiency improve by 6.0% and 11.9%, respectively. In this case, a decrement of 1.18 $/GJ (10.7%) is obtained in the overall unit cost of products compared to the conventional CPER system.

Thermo-enviro-exergoeconomic analysis and multi-objective optimization of a novel geothermal-solar-wind micro-multi-energy system for cleaner energy production

Renewable energy- based multigeneration systems have been proposed as a viable means of achieving a net-zero future as these systems can decarbonize the power and energy sector simultaneously. Although there has been significant development in this research field, the large sizes of the existing systems in literature are a major setback in the adoption/implementation of these systems. Furthermore, the unavailability of solar and wind energy during some hours daily makes solar or wind energy-based multigeneration systems undesirable in many applications. Considering the urgency/importance of attaining a net-zero emission future, this study presents a novel multi-energy system that can bridge the existing gaps in literature. Therefore, the thermodynamics, economic, and environmental analysis novel CO2-based geothermal micro-multi-energy system that is hybridized with a concentrated solar photovoltaic/thermal system and wind turbine is presented in this paper. The proposed energy system presents an innovative method that can be effectively used to decarbonize future energy production. The multi-energy system is modeled to produce electricity, refrigeration effect, space heating, hydrogen, and hot water. The economic study in this paper also analyzed the Levelized cost of electricity (LCOE), Levelized cost of cooling (LCOC), and Levelized cost of hydrogen (LCOH). A multi-objective optimization operation is also carried out on the modeled system in order to determine the optimal exergy efficiency and total product unit cost. The steady-state performance analyses showed that the overall energetic and exergetic efficiencies of the system are 48,61% and 88.31% and these efficiencies can be as high as 51.76% and 95.08% respectively when the system is optimized with reference to exergy efficiency. The LCOE, LCOC, and LCOH at the optimal total product unit cost are 0.04529 $/kWh, 0.004564 $/kWh, and 28.86 $/kg.

Techno-economic analysis on the production of domestic water using solar-driven membrane seawater desalination device in the Philippines

This study investigates the technical design and economic assessment of an industrial plant that produces 160 m3/day of domestic water using solar-driven membrane seawater desalination technology. The proposed desalination plant in Barangay Nalus, Kiamba, Sarangani Province, Philippines, has three main processing areas. These areas include the pre-treatment for particle removal, desalination of seawater, and post-treatment to comply with domestic water standards in the country. The economic assessment revealed a total capital expenditure of $2,364,317.00 with a unit product cost of $9.75/m3 or a selling price of $12.68/m3 with a 30% markup. The high capital and product costs are due to the low production rate, the novelty of the technology, expensive membrane cost, and extensive land area requirement. Profitability analysis for a selling price of $12.68/m3 revealed a more than 14-year payback period, a loss of $235,000.00, and a high 41% chance of being unprofitable. Reducing the product price to a market price of $1.17/m3 also reveals no profit at all: a loss of $4.6 million and a 100% chance of being unprofitable. Thus, it is highly recommended to delay construction of the proposed plant until the technology becomes matured and fully developed to produce a competitive price-wise membrane-based desalinated seawater.