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p>Trigeneration is the combined production of heating, cooling and power from the same source of energy. In this paper, the operation of a simple trigeneration system is analyzed. The system is interconnected to the electric utility grid, both to receive electricity and to deliver surplus electricity. For any given demand required by the users, a g...
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As a direct result of economic pressures to cut expenses, as well as the legal obligation to reduce emissions, companies and businesses are seeking ways to use energy more efficiently. Trigeneration systems (CHCP: Combined Heating, Cooling and Power generation) allow greater operational flexibility at sites with a variable demand for energy in the...
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... While determining the optimal working method especially for use in a trigeneration system, many factors affect the determination of the very dynamic working regime such as electricity trading and unit costs determined by EPDK [13], working conditions and working environment, city conditions, post-investment maintenance and operating costs of the units selected in the installed system, and fuel costs used in the system [14,15]. Thanks to cleverly developed methods, it should be an improvement in the selected equipment and investment amounts [16]. ...
... HT unit high temperature exchanger (9)(10)(11)(12) LT unit cooling radiator (13)(14) HT unit cooling radiator (15-16) In order for the trigeneration system to be operated in accordance with the winter season, all the principles described above are the same for the system. It is calculated and read the Ėx values of the flows input and output in the trigeneration system for the winter season from Tables 7-10. ...
In this study, the feasibility of the trigeneration system, which is one of the on-site energy production methods, was determined for Kocaeli University Umuttepe Campus, exergy and energy analyses were made for each point of the system and exergy destruction in the lines was found. The key point of the gains, losses, and efficiency analyses in the lines are presented with engineering solutions and thermodynamic proofs. The seasonal mathematical models covering the whole of the feasibility of the trigeneration system were carried out and the energy and equilibrium equations of the entire system were established. In addition, energy and exergy analysis, 2nd law efficiency, coefficient of performance (COP), and thermal efficiency were calculated for all the systems. The seasonal numerical analyses of the system have been prepared so that it can work effectively in two different working disciplines separately for summer and winter seasons. Thanks to these numerical analyses that are mentioned, the seasonal exergic destructions of the system are found, seasonal working methods are shown, and working conditions and operating load values suitable for the current season are determined. In addition, in the light of the technical studies mentioned above, both the hourly energy capacities and hourly consumption values that the university will produce after trigeneration have been compared by performing separate mathematical models for summer and winter modes. Thus, it has been aimed to reduce the energy production costs by selling the excess energy to the mains. It is for this reason that it is aimed to reduce the energy production costs of the country, to reduce foreign dependency to meet energy demand, to present both a ready to apply feasibility report to investors and a ready to use design of a medium-sized power plant that will set an example of trigeneration studies in academic terms. In today’s practical applications, it is known that the system efficiency of trigeneration systems can be between 70 and 80%. In the light of the studies, 66% exergic efficiency in winter, thermal efficiency of 0.87411 with 2.05 MW thermal capacity, 63% exergic efficiency in summer, COP of 0.82 with 1.5 MW cooling capacity, and 2.02 MWe instantaneous electrical power was found in summer and winter. It was decided that the system could be a facility that is technically open to development and worth establishing in the light of the exergic and energetic analyses results obtained in this study and the exergic system efficiency comparisons made in the literature. In this study, attention was drawn to the importance of exergy and energy analyses in deciding the installation of a trigeneration system, and it was shown that exergic and energetic analyses played a key role in the verification of decision mechanisms. In order to give an idea for other studies in the literature, it is aimed to draw attention to the need to perform seasonal exergy and energy analyses of the designed or desired trigeneration systems.
... While determining the optimal working method especially for use in a Trigeneration System, many factors affect the determination of the very dynamic working regime such as electricity trading and unit costs determined by EPDK [1], working conditions and working environment, city conditions, post-investment maintenance and operating costs of the units selected in the installed system, and fuel costs used in the system. [14], [19]. While electricity consumption is between 08:00-22:00 for the first part of Umuttepe, considering the training for 6 days a week, for the second part of Umuttepe, uninterrupted electricity production is required for 7 days and 24 hours. ...
In this study, a feasibility of the trigeneration system, which is one of the on-site energy production methods, was prepared for Kocaeli University Umuttepe Campus, and energy and exergy analyses were made for each point of the system and exergy destruction in the lines was found. It is aimed to be able to produce the energy, which is the most basic indicator of sustainability, at the closest point to the consumption place, thus keeping the distribution and transmission losses at a minimum level and dimensioning the designed system. The key point of the gains, losses and efficiency analyses in the lines is presented with engineering calculations based on thermodynamic proofs, exergetic efficiency and losses, the energy and balance equations of the whole system, and the feasibility of the entire trigeneration system, including mathematical modeling, energy analysis, the whole system in II. Law Efficiency, COP, Thermal efficiency were calculated. The seasonal working methods were shown by the numerical analyses prepared in the summer and winter working disciplines of the system effectively and the seasonal working methods were found and the working conditions and operating load values suitable for the current season of the system were found. In addition, by performing separate mathematical models for summer and winter mode, in the light of the above-mentioned technical studies, both the reduction in the energy production costs of the country thanks to the energy that the university will produce in-house, the reduction of foreign dependency in energy demand, a feasibility report ready for investors and an academic. In this sense, it is aimed to present a ready-to-use design of a medium-sized power plant that will set an example for trigeneration studies. From the designed system; 66% exergic efficiency in winter, thermal efficiency 0.87411 with 2.05 MW thermal capacity, 63% exergic efficiency in summer, COP 0.82 and 1.5 MW cooling capacity, and 2.02 MWe instantaneous electrical power was found in summer and winter. The results have shown us that the designed system can be a facility that is open to development and worth establishing with the results obtained technically. Based on the current applications made so far, it has been determined that there are similar results between the studies in the literature and the exergy and energy analyses of the trigeneration system, which we have made feasibility in Umuttepe campus and are close to the findings obtained in the calculations in the literature.
... This improvement used a mixed integer linear programming (MILP) method. Piacentino et al. and Lozano et al. [24,25] used MILP to carry out thermoeconomic analysis of trigeneration systems. Piacentino and Barbaro [26] developed a MILP tool that discretized the optimization into synthesis, design and operation levels where different binary variables defined whether the component was selected, and whether it was operating at a certain time interval. ...
Optimization of energy systems witnessed the use of simple (constant efficiency) equipment models. Alternatively, grey-box (variable efficiency with part load) models were used to simulate a more real behavior of such systems. However, limited attention was given to deviations due to part load effect in planning, sizing, scheduling and sensitivity analyses. This paper provides a quantified methodology to reflect such deviations and to show to what extent simple model is valid. A detailed comparison between both models is developed by optimizing a trigeneration system to find its configuration, rated capacities, operating schedule and sensitivity to prices. A data-driven comparative criterion -root mean square deviation- is developed to compare models. It depends on deviations in combined efficiency that is based on four key performance energy, economy, environment and exergy indicators in addition to economic parameters being the decision attributes. Results show that the deviations in the combined efficiency; net present value; payback period; and internal rate of return are 40.45%; −71.26%; 30.37%; and −24.30% respectively, leading to an overall root mean square deviation of 45.35%. Simple model approach is valid to be used in the planning phase only. However, the grey-box model is the way forward for optimization of polygeneration systems.
... More details on exergoeconomics can be found in Lazzaretto and Tsatsaronis [10], Tsatsaronis [11], and Ahmadi and Dincer [12]. Exergoeconomics has been employed for cost allocation purposes in a multi-product system by Chun, Barone, and Lourenço [13], while simple trigeneration systems were the focus of Lozano et al. [14] and Carvalho et al. [15]. A comprehensive literature review on energy, exergy, exergoeconomic, and economic analyses of thermal power plants was presented by Kumar [16]. ...
... The exergy of the combustion products, considering the thermomechanical and chemical contributions, is calculated by Eqs. (14) and (15): h and s refer to enthalpy and entropy flows, respectively, v refers to the speed, g is the gravity, z is the height, and ex che,flow is the chemical exergy of the flow. R is the universal gas constant, y i is the molar fraction of a component, and y e i is the molar fraction of an environmental component. ...
This study presents energy, exergy, and exergoeconomic assessments for a natural gas-fueled micro-trigeneration unit, which encompasses an internal combustion engine (ICE), an absorption refrigeration system (ammonia–water), and a heat recovery unit. The energy system is designed to meet the electricity and cooling demands of a university building, while heat is directed to a biodiesel plant located on site. The analyses comprehended energy and exergy parameters (first and second laws of thermodynamics). Then, the SPECO methodology was applied for the exergoeconomic assessment, which associates monetary values with exergy flows. The ICE presented the highest irreversibility (61.24 kW) and the highest cost of exergy destruction (21.56 BRL/h), followed by the steam generator (5.52 kW and 6.71 BRL/h, respectively). The exergoeconomic assessment indicated the components that could benefit from improvements: steam generator (cooling of exhaust gases before entry into the generator) and the heat exchanger of the absorber (substitution of the exchanger and/or pre-heating of input air). This study contributes to narrow the knowledge gap regarding the exergoeconomic assessment of compact trigeneration systems, besides making a case for the utilization of ICE as prime movers.
... Obtaining unit costs of internal flows and final products is a cornerstone of several thermoeconomic methodologies that have been presented in the literature [52]. Lozano et al. [34] applied three different approaches to determine the unit costs of the Table 1 Technical parameters and capacity limits of the trigeneration system's devices. ...
... Marginal costs give valuable insight into the operation of the system, explaining how and why the system operates given a change in external circumstances (e.g. increase in the consumer center's energy demand). On the downside, marginal costs are generally not appropriate to explain the actual production of the system [50,52,53], apart from not being conservative [34,50]. In Ref. [50], the authors have used marginal costs to explain the optimal operation of the simple trigeneration system described in Section 2 and the role of the TES unit in achieving the optimal operation. ...
... In accordance with the objective of promoting widespread acceptance of polygeneration systems in society through a fair costand-benefit apportionment of joint production costs, it was proposed to apply the same discount d to all products of the trigeneration subsystem with respect to a reference cost of the corresponding energy services production. In previous papers [27,28,34], the authors have applied the discount method in similar thermoeconomic analyses of trigeneration systems. ...
The present paper tackles the issue of allocating economic costs in trigeneration systems including thermal energy storage (TES) for buildings of the residential-commercial sector. As energy systems become more and more complex (multiple resources, products and technologies; joint production; TES) the issue of the appropriate way to allocate the cost of the resources consumed arises. This is important because the way in which allocation is made directly affects the prices of the products obtained and, thus, the consumers' behavior. Thermoeconomics has been used to explain the cost formation process in complex energy systems. In this paper, two issues in thermoeconomics that have not been deeply studied are addressed: (i) the joint production of energy services in dynamic energy systems; and (ii) the incorporation of TES. A thermoeconomic analysis of a simple trigeneration system including TES was performed and the hourly unit costs of the internal flows and final products were obtained for a day of the year. The cost allocation proposal considered that the cogenerated products must share the benefits of the joint production. Regarding the TES, the interconnection between charging and discharging periods was explored, allowing the discharged energy flow to be traced back to its production period.
... Three different approaches to determine the unit costs of internal flows and final products of a simple trigeneration system were presented in Ref. [29], namely marginal cost analysis, valuation of products according to their market prices, and internal costs calculation. It was concluded that the calculation method must be selected based on the specific objectives of the analysis. ...
The development of high-efficiency energy systems is a pressing issue nowadays, motivated by economic, environmental, and social aspects. Trigeneration systems allow for the rational use of energy by means of appropriate energy integration and provide greater operational flexibility, which is particularly interesting for buildings, often characterized by variable electricity, heating, and cooling demands. The benefits of trigeneration systems can be enhanced by the incorporation of thermal energy storage (TES), which decouples production and consumption. This paper analyses the operation of a simple trigeneration system including TES. The optimal operation is obtained by a linear programming model that minimizes the total variable cost. A thermoeconomic analysis based on marginal cost assessment of the internal flows and final products of the system is carried out, allowing to explain the optimal operation of the system and the role of the TES in achieving the optimal solution. The analysis unravels the marginal cost formation process, presenting a clear route from the final products obtained to the resources consumed. This information can aid the design of new plants, the retrofit of existing ones, and the operational management to achieve the minimum operational cost.
... Various scholars have investigated the CCHPPs based on the method of classical thermodynamics. Lozano et al. [3] investigated the thermo-economic index of the CCHPP with specified user demand, and obtained the minimum variable cost based on linear programming method. They pointed out that the heat prices had evident effects on the production costs, and the best approach was determined by the issue conditions. ...
... Various scholars have investigated the CCHPPs based on the method of classical thermodynamics. Lozano et al. [3] investigated the thermo-economic index of the CCHPP with specified user demand, and obtained the minimum variable cost based on linear programming method. They pointed out that the heat prices had evident effects on the production costs, and the best approach was determined by the issue conditions. ...
A combined cooling, heating and power plant (CCHPP), composed of an endoreversible closed Brayton cycle and absorption refrigerator, is studied in this paper. By introducing the finite time thermodynamics, the formula of the exergy output rate (EOR) of the CCHPP is derived. With the help of Powell arithmetic, the compressor pressure ratio of the Brayton cycle and distributions of 7 heat exchanger heat conductances (HEHCs) are optimized, and the maximum EOR of the CCHPP is obtained. It shows that the hot-side HEHC is the largest one among the discussed HEHCs, and several parameters, such as the total HEHC and ratio of heat reservoir temperature to the surrounding temperature, on the optimal performances of the CCHPP are analyzed.
... Further, techno-economic assessments of heat and cold thermal storage systems have been applied, often using advanced methods like exergoeconomics (economics based on exergy)(Rosen 2011;Mosaffa and Garousi Farshi 2016). The economics of thermal storage systems in conjunction with cogeneration, trigeneration and DE have also been the subject of numerous investigations(Rentizelas et al. 2009;Lozano et al. 2009aLozano et al. , 2010 Balli et al. 2010; Dominković et al. 2015), including thermoeconomic analyses(Balli et al. 2010) and economic optimization of designs(Lozano et al. 2010). ...
The status and needs relating to the optimal design of community seasonal energy storage are reported. Thermal energy storage research has often focused on technology development and integration into buildings, but little emphasis has been placed on the most advantageous use of thermal storage in community energy systems. Depending on the composition and characteristics of a community, the most appropriate community thermal storage may differ from that for a single building. District energy systems usually link thermal users to cold supplies and/or heat supplies (e.g., solar thermal energy, geothermal energy from ground-source heat pumps or geothermal hot zones, industrial waste heat, thermal energy from cogeneration or trigeneration). It is demonstrated that the optimal integration of these technologies can be enhanced through the use of appropriate seasonal thermal energy storage and that community-level seasonal storage can facilitate the development of smart net-zero energy buildings and yield efficiency, economic and environmental benefits. Issues that need to be resolved to allow optimal solutions to be attained are described. Advanced tools are required for modeling, simulation, analysis, improvement, design and optimization, which incorporate advanced methods like exergy analysis. The most appropriate scale, number and type (e.g., sensible, latent, thermochemical) of thermal storages in a community need to be better assessed, and the appropriate time duration capacities for each determined in an optimal manner. This is particularly important since a combination of short-, medium- and long-term storage is sometimes required to yield the most benefits from community energy systems.
... Applying the cost conservation principle as described in Lozano et al. (2009a) to PV+V, ST+T, AB and P brings cWpvv, cQstt, cQa and cEd, respectively. There remain 5 unit costs to be determined (cWcc, cQcc, cQin, cQout, cQd). ...
This work aims to perform a thermoeconomic analysis of a cogeneration system assisted with solar thermal heat and photovoltaic power, and determine the daily optimal operation taking into consideration the effects of thermal energy storage (TES) and hourly variations of solar radiation, energy prices and energy demands. The system is considered to be interconnected to the national electric grid, thus purchase and selling of electricity are possible. A linear programming model was developed to represent the hourly operation of the system. The results presented herein correspond to the optimal operation for a representative day in April. It was shown that the cogeneration module operates at full load throughout the day and the system sells electricity to the grid for a total of 8 hours. The marginal cost analysis showed the different situations in which heat is charged/discharged to/from the TES and how it affects the unit cost of the heat produced. It has been proposed a thermoeconomic model that incorporates a new set of equations to contribute towards a better understanding of the charge and discharge in different time periods in the TES. The obtained unit costs for internal flows and products showed that the electricity and heat produced by the cogeneration system are always cheaper than the separate conventional production (43-53% cheaper for the electricity and 19-67% cheaper for the heat).
