Thermoeconomic Diagnosis Research Articles

Proposal for an Intelligent Methodology to Manage Energy in Buildings and Detect Anomalies as a Compass Towards Zero Energy Buildings (ZEB)

This work aims to advance the optimisation of the efficiency of thermal installations in buildings, contributing to the achievement of Zero Energy Buildings (ZEB) in the context of maintenance and operation. This is achieved through an innovative proposal that merges machine learning techniques with thermoeconomics to perform diagnoses in building thermal systems and identify cost overruns generated by intrinsic anomalies in the components and quantify their induced effects on the rest of the components. To date, the few contributions combining these techniques have been limited to industrial applications and cost calculation, without addressing their application to building thermal systems, both from a dynamic perspective and for maintenance purposes. Research using Physics-Informed Neural Networks, PINNs, in this area is even scarcer, which underlines the complexity of defining a suitable methodology. Thus, the proposal integrates PINNs with a thermoeconomic diagnosis based on characteristic curves, allowing the comparison of the current operating condition with an anomaly-free reference condition to assess the existence of anomalies and their effects. For this reason, reference models are generated for the first time with PINNs, which represents a break with the conventional maintenance approaches used by professionals in the sector. Therefore, this methodology incorporates techniques that require specialised knowledge in thermodynamic and informatics areas, which motivates the present work to be focused on the exhaustive description of the methodology and to highlight the importance of continuing to explore lines of research in this unexplored field.

Thermoeconomic model for diagnostic techniques to evaluated vapor compression refrigeration system performance

In recent years, it has been possible to observe a significant expansion of the refrigeration and air conditioning industry. Considering that food refrigeration systems (blast chilling or freezing, cold storage, retail display, etc.) and air conditioners are large energy consumers, this work presents a methodology for evaluating the performance and behaviour of these systems using the thermoeconomic diagnosis concept. The thermoeconomic model used allowed the definition of the condenser and expansion device products, which is not trivial for these components. With that, the thermoeconomic diagnosis was used to evaluate the degradation of refrigeration system components, together with the influence of individual component degradations on efficiency, cooling capacity, operating parameters, and power consumption of the whole system. Through this analysis, a prognosis of system behaviour was obtained, which can be used for maintenance scheduling, as well as for the comprehensive energetic and exergetic analysis of a refrigeration system and each of its components.

Evaluation of the influence of exergy disaggregation on the results of thermoeconomic diagnosis using exergetic operators

Thermoeconomic diagnosis is a tool to locate malfunctions and quantify their impact on thermal system operating costs. Since diagnostic methodologies are mainly based on the iteration of exergy flows within thermal systems, some authors suggest that the results can be improved when exergy is disaggregated into its components. Therefore, a Rankine cycle with intrinsic malfunctions in the condenser and the steam turbine was diagnosed using the thermoeconomic diagnostic methodology with exergetic operators for the thermoeconomic models of total exergy and physical exergy disaggregated into its enthalpic and negentropic portions. To enhance the study, the total exergy and negentropy model was also used. The applied method can identify intrinsic malfunctions, induced malfunctions, and dysfunctions. However, contrary to what would be expected, the results regarding the intrinsic malfunctions were the same for the three thermoeconomic models evaluated. Furthermore, the thermoeconomic model did not affect the value obtained when adding induced malfunctions and dysfunctions. Thus, the fuel impact was divided into its intrinsic and induced parcels. These parcels also remain independent of the thermoeconomic model, allowing the same results to be obtained with less complexity when the methodology is applied directly to the transition structure without needing a productive structure.

Thermoeconomic diagnosis as a tool to account the effect of climate change in buildings thermal facilities. Case study of a geothermal facility in Spain

The energy demand supplied to buildings thermal facilities is changing due to the rise in ambient temperature provoked by climate change. Thus, the aim of this work is to develop a tool for quantifying the effects of climate change on thermal facilities, filling a research gap in the area of thermoeconomic diagnosis in relation to the effects produced by the change in ambient temperature. In turn, this diagnosis links the rise in ambient temperature with the exergy value of the facilities' matter flows, that depends on the reference temperature characterized with the ambient temperature. TRNSYS software is used to model a facility in two climate scenarios: one, at the current location and the other, warmer, which represents the one affected by climate change. Data obtained from both simulations is introduced in a thermoeconomic software that gives the fuel impact indicator and the thermodynamic costs of the flows with respect to the reference condition. It is found, that the rise in ambient temperature means a decrease in the quality of the DHW flow by −838 kWh/year and an increase in the irreversibilities of 838 kWh/year, resulting in an increase in the thermoeconomic costs of the DHW flow. This effect is detectable only with the techniques based on the second principle such us thermoeconomic diagnosis. Therefore, this research presents a novel tool to fight against climate change, as shown by the results.

4E, risk, diagnosis, and availability evaluation for optimal design of a novel biomass-solar-wind driven polygeneration system

In this study, an innovative hybrid biomass-solar-wind driven polygeneration system has been presented. The presented system is integrated with two fuel cells and two electrolyzers. Also, considering the approach of using renewable systems, solar, and wind systems have been used in this system. The system integrated by two biomass fuels, olive pits and municipal solid waste (MSW), was examined for energy, exergy, exergoeconomic, and exergoenvironmental (4E) analysis and the results obtained from the 4E analysis of both fuels were compared with each other. The multigeneration system was examined from the point of view of risk and hazard of integrated systems, and the results showed that organic Rankine cycles (ORC) integrated into this system have high risk. Also, the system was evaluated by thermoeconomic diagnosis in terms of malfunction in the operation of the equipment. This evaluation indicates that solid oxide fuel cell (SOFC) performs well compared to other equipment. In addition, the results of this evaluation determined that the system in the functional state can consume fewer local resources than the reference state. Also, the proposed system was tested by assessing reliability and availability. In this analysis, while checking accessibility, the scenarios of increasing accessibility were discussed. Finally, considering this evaluation's effect, the system's cost and environmental impact were calculated. Finally, the polygeneration system was subjected to three-objective and four-objective optimization with the help of genetic and Lichtenberg algorithms. The objective functions selected for optimization are polygeneration efficiency, total cost rate, environmental impact rate, and risk.

Application of Circular Thermoeconomics to the Diagnosis of Energy Systems

This paper reviews the fundamentals of the thermoeconomic diagnosis theory. Thermoeconomic diagnosis is one of the main applications of the exergy cost theory used to identify the causes of additional resource consumption of a system due to inefficiencies in its components, published in the late 1990s. Thermoeconomic diagnosis has usually been applied to diagnose power plants with high consumption of fossil fuels and fixed production. However, it does not consider the final production and waste generation variation. In this paper, Circular Thermoeconomics is applied to analyze in depth the effect of malfunctions on additional waste generation and changes in the final output of the system. This new formulation can be applied to polygeneration systems, where there is a simultaneous variation of final products, and to process integration and industrial symbiosis, where a part of the waste generated by a plant could be reused in other processes or plants.

Exergy Cost Accounting Analysis of New Hybrid Solar Organic Rankine Cycle-MSF Desalination System for Pasabandar Region in Gwadar Bay

An energy system affordable plan selection using renewable energy is a significant problem for designing and manufacturing these systems. The fault detection and thermoeconomic diagnosis in the combined solar Rankine cycle and multi-stage flash (MSF) desalination system is analyzed. In the suggested energy system, the linear parabolic solar collector is utilized as a heat source for the organic Rankine cycle, the domestic hot water, and the multi-stage-flash desalination system. First, the energy balances and exergy analysis are implemented in the considered system, the energy value and exergy parameter are calculated. The exergy cost parameters are calculated for all parts and streams with the thermoeconomic and exergy cost accounting investigation. Finally, the thermoeconomic diagnosis is performed, and the malfunction of each component is evaluated, and the effect of each component's irreversibility on the other part is investigated. Results show that the linear parabolic solar collector has the maximum malfunction. Still, the condenser in the organic Rankine cycle is the most effective component on irreversibility increment among its counterparts..

Thermoeconomic Diagnosis of the Sequential Combustion Gas Turbine ABB/Alstom GT24

In this study, we used the thermoeconomic theory to evaluate the impact of residue cost formation on the cost of electricity generated from natural gas burned in a gas turbine that applied sequential combustion; we also analyzed the impact of the combustion process on the additional fuel consumption to compensate for a malfunction component. We used the Alstom GT24 gas turbine, which applied sequential combustion and generated 235 MW of power. Thermoeconomic analysis indicated that the exergy cost of power generation was 626.33 MW (30.42% corresponded to irreversibility costs, and 29.22% and 2.84% corresponded to the formation costs of physical and chemical residues, respectively). The exergoeconomic production cost of gas turbine was 10,098.71 USD/h, 34.76% from external resources and 65.24% from capital and operating costs. Thermoeconomic diagnosis revealed that a compressor deterioration (of 1-% drop in the isentropic efficiency) resulted in an additional fuel consumption of 4.05 MW to compensate for an increase in irreversibilities (1.97 MW) and residues (2.08 MW); the compressor generated the highest cost (49.9% of additional requirement). Thus, our study can identify the origin of anomalies in a gas-turbine system and explain their effects on the rest of the components.

On the Allocation of Residues Cost using Conventional and Comprehensive Thermoeconomic Diagrams

In a productive process, the achievement of products occurs simultaneously with residues generation. Environmental impact of residues is an important issue in energy systems analysis due to environmental regulations and sustainability assessment. Many waste treatment methodologies have been proposed and applied in thermoeconomics. However, this is a complex problem and the solution depends on the residue nature and its formation process. Most conventional methodologies are based on productive diagrams, using productive flows only, and allocate the residues cost among the productive equipment. This work surveys the main conventional methodologies for treatment of waste and presents an improved/updated methodology based on a comprehensive diagram, in which both physical and productive flows are represented and their flows cost are assessed and the subsystems are connected using the same physical flows presented in the flowsheet of the plant. Both the CGAM system and a combined cycle are analyzed. Comparisons are made with literature results, considering the same case studies. The presented methodology obtains consistent results from the point of view of the cost allocation in thermoeconomics. The novelty of this updated approach concerns how the residue cost is allocated in the comprehensive diagram: it is reinternalized in the internal loop of physical flows, instead of in the productive unit. It represents advantages since the equipment product/fuel ratio index is not affected, which is beneficial for thermoeconomic diagnosis application.

The Exergy Cost Theory Revisited

This paper reviews the fundamentals of the Exergy Cost Theory, an energy cost accounting methodology to evaluate the physical costs of products of energy systems and their associated waste. Besides, a mathematical and computationally approach is presented, which will allow the practitioner to carry out studies on production systems regardless of their structural complexity. The exergy cost theory was proposed in 1986 by Valero et al. in their “General theory of exergy savings”. It has been recognized as a powerful tool in the analysis of energy systems and has been applied to the evaluation of energy saving alternatives, local optimisation, thermoeconomic diagnosis, or industrial symbiosis. The waste cost formation process is presented from a thermodynamic perspective rather than the economist’s approach. It is proposed to consider waste as external irreversibilities occurring in plant processes. A new concept, called irreversibility carrier, is introduced, which will allow the identification of the origin, transfer, partial recovery, and disposal of waste.

On the accuracy improvement of thermoeconomic diagnosis through exergy disaggregation and dissipative equipment isolation

Thermoeconomics join the concepts of Economics and Thermodynamics in order to describe the cost formation process of the overall thermal system. It has great applicability in product cost allocation, optimisation, and diagnosis, aiming to reduce operating costs and to prove a system’s economic feasibility. Thermoeconomic diagnosis is applied to identify the source of extra fuel consumption in each system element. In this study, a power generation system and a heat pump, each with different simulated anomalies, are evaluated by five distinct thermoeconomic models based on productive diagrams (E, E&S, H&S, UFS and UFS+) combined with the fuel impact formula, focusing on its efficiency to quantify the effects of each malfunction with the presence of a dissipative component. For the power generation, the H&S and UFS models presented satisfactory results in correctly identifying the faulty component, whereas, in the heat pump system, the fictitious unities from the productive diagram interfered with the results, inhibiting the determination of the element with an intrinsic fault. Moreover, the UFS and UFS+ models were able to isolate all equipment in the productive diagram for the latter system.

Disaggregation models for the thermoeconomic diagnosis of a vapor compression refrigeration system

The demand for chilled or frozen pre-cooked food and also for conditioned air has increased significantly in the last years. It is also well known that food refrigeration systems (blast chilling or freezing, cold storage, etc.) and air conditioners are important energy consumers in the tertiary sector. Thus, proper diagnosis techniques are important to avoid excessive energy consumption and to assure that the cooling demands will be met. In order to predict the performance of these systems under off-design conditions, mathematical models of refrigeration and air conditioning systems are presented. Besides that, four malfunctions are simulated and the equilibrium condition for each one of them is calculated. Two thermoeconomic methodologies are used to evaluate the fuel impact of each degradation. It was revealed that different values of degradations and dysfunctions were calculated even though the same fuel impact was obtained. One of the productive structures assessed presented more suitable results for the diagnosis of anomalies due to its use of fewer fictitious flows, which are known to incorrectly influence in the magnitude of exergy flows leading to improper results. Further studies regarding the structure of the malfunctions (intrinsic and induced components) are needed for more accurate diagnosis in refrigeration systems.

Exergy cost accounting and thermoeconomic diagnosis for Double-Solar-Gas-Turbine system (DSGT)

ABSTRACT The selection of the cost-effective design for energy systems is one of the important issues in the design and optimization of the power generation systems. To achieve this goal, the thermodynamic analysis and fault detection is one of the useful methods. Thus, in this paper, the thermoeconomic diagnosis and fault detection method is used for the selection of effective Double-Solar-Gas-Turbine system (DSGT). In the proposed DSGT system, the heliostat solar system and combustion of fossil fuel are used as a heat source of the power plant. To achieve the research goals, in the first steps, the energy and exergy analysis is performed, and the energy and exergy parameter is evaluated. Then, the thermoeconomic and the exergy cost accounting analysis is performed and based on this analysis; the exergy cost parameters are examined for all the components and flows. Finally, the malfunction of each component is evaluated with the thermoeconomic diagnosis approach and based on this approach, the effects of irreversibility in each component on other components are investigated. Results show that one of the heat exchangers (intercooler in the bottom cycle) has the highest exergetic cost in comparison to other components, but this heat exchanger has a very small impact on the irreversibility of other components. Conversely, the heat recovery heat exchanger (recovery between the two cycles) has a major effect on the irreversibility of other components, and thus the most correction should be performed in this converter.

Performance maps for an air-cooled air conditioning system as a preliminary instrument for the diagnosis of evaporator fouling

During the past few decades, there has been increased interest in the development of automated approaches for detecting and diagnosing faults in air conditioning systems. Among them, thermoeconomic diagnosis is a technique which involves the use of exergy analysis. As a first step towards improving its performance, this work is focused on the thermodynamic and exergy analysis of a direct expansion air conditioning system used in small commercial building applications. The analysis was carried out by means of experimental activities on a 17.5 kW rooftop unit installed at the Herrick Laboratories, Purdue University, Indiana (USA). The system under investigation was equipped with a variable-speed compressor and variable-speed fans, thus allowing the unit to meet different loads. A detailed mapping of the performance of this system was carried out by considering the effect of the outdoor temperature and the cooling load. In addition, the effect of evaporator fouling was investigated. Results showed that poor exergy performance were achieved due to the exergy destruction occurring in the evaporator. Also, when testing evaporator fouling, results showed that this fault contributed to increase the consumption of the mechanical exergy of the air, thus allowing for an easy detection of this fault.

Thermoeconomic diagnosis and malfunction decomposition: Methodology improvement of the Thermoeconomic Input-Output Analysis (TIOA)

Faults and malfunctions occurring in engineering systems may cause additional resources consumptions and economic expenditures, thus their detection and isolation is of great practical significance. The procedure to discover faults is known as diagnosis, and it can be based on different techniques, depending on the purpose of the analysis: to predict the failure time of the component, or to quantify the inefficiencies of the system due to the anomaly. Among the existing approaches adopted to diagnose the energy systems, Thermoeconomic diagnosis provides useful information to detect the anomalies and to quantify its negative impacts. However, this method does not allow to identify possible strategies useful to reduce the inefficiencies caused by anomalies, which could be a crucial need for the system operator.To face this issue, this article proposes a method to perform Thermoeconomic diagnosis of energy systems that enables the analyst to understand the interdependencies between the components, and decomposing the main indicator resulting from Thermoeconomic diagnosis, known as malfunction. The method provides useful information for the system operators to define practical strategies to reduce the negative effects of malfunctions. This approach is also formalized and applied to the CGAM benchmark to highlight the practical achievements of this approach with numerical values. It is found that the proposed approach provides useful insight about the effects of malfunctions, and it may be helpful for system operators to reduce the negative impacts of the anomaly by pinpointing the component with higher contribution in total inefficiency of the system. In this specific case, proper intervention on the pinpointed component mitigated the total inefficiency of the system by almost 40%, and recovered the reference efficiency of the system.

Thermoeconomic diagnosis of an air-cooled air conditioning system

Thermoeconomic diagnosis of an air-cooled air conditioning system

Thermoeconomic diagnosis of an air-cooled air conditioning system

Diagnosis of a 120-kW air-cooled air conditioning system under faulty conditions was performed using modified productive structure analysis. Unit cost of cooling capacity for the system and lost cost flow rate for components were calculated based on data obtained by using a simulator for the cases of pre-fixed faulty and normal operating conditions. The relative malfunction (RMF) and the relative difference in the lost cost flow rate between real and normal operations (RDLC) were found to be effective indicators to identify the malfunction components. Results revealed that malfunction due to fouling at the condenser and evaporator, compressor valve leakage, the superheating in the suction line and refrigerant undercharge, whose fault levels by the percent degradation induced in the cooling capacity are 3.4%, 10.5%, 15.1%, 3.5% and 4.1%, respectively, can be identified. Unit cost of the cooling capacity of the system increases when malfunction occurs at any component in the air conditioning system.

On Thermoeconomic Diagnosis of a Fouled Direct Expansion Coil: Effects of Induced Malfunctions on Quantitative Performance of the Diagnostic Technique

On Thermoeconomic Diagnosis of a Fouled Direct Expansion Coil: Effects of Induced Malfunctions on Quantitative Performance of the Diagnostic Technique

A comparative analysis of two thermoeconomic diagnosis methodologies in a building heating and DHW facility

Concerning the building environment HVAC facilities, even if a great effort has been made in developing components and systems with high nominal efficiencies, less attention has been paid to the problem of system maintenance.The main objective of the thermoeconomic diagnosis is to detect possible anomalies and their location inside a component of the energy system. The second objective, and indeed the one to be achieved in this paper, is indicated as inverse problem. It is associated with the quantification of the effects of anomalies in terms of thermoeconomic quantities. Its rigorous application in building thermal installations has some difficulties relating to the strong interrelation between the different components and the fact that energy supply facilities are continuously changing with time.The way to deal with dynamic circumstances is thoroughly explored in this article. Likewise, this paper’s main goal is to demonstrate an application of two thermoeconomic diagnosis methodologies in the building sector, one based on the malfunction and dysfunction analysis and the other one based on the characteristic curves of the components. The results obtained allow us to point out the advantages and limitations of both methodologies as well as to combine them and then develop a more reliable diagnosis.

Two Thermoeconomic Diagnosis Methods Applied to Representative Operating Data of a Commercial Transcritical Refrigeration Plant

In order to investigate options for improving the maintenance protocol of commercial refrigeration plants, two thermoeconomic diagnosis methods were evaluated on a state-of-the-art refrigeration plant. A common relative indicator was proposed for the two methods in order to directly compare the quality of malfunction identification. Both methods were applicable to locate and categorise the malfunctions when using steady state data without measurement uncertainties. By introduction of measurement uncertainty, the categorisation of malfunctions became increasingly difficult, though depending on the magnitude of the uncertainties. Two different uncertainty scenarios were evaluated, as the use of repeated measurements yields a lower magnitude of uncertainty. The two methods show similar performance in the presented study for both of the considered measurement uncertainty scenarios. However, only in the low measurement uncertainty scenario, both methods are applicable to locate the causes of the malfunctions. For both the scenarios an outlier limit was found, which determines if it was possible to reject a high relative indicator based on measurement uncertainty. For high uncertainties, the threshold value of the relative indicator was 35, whereas for low uncertainties one of the methods resulted in a threshold at 8. Additionally, the contribution of different measuring instruments to the relative indicator in two central components was analysed. It shows that the contribution was component dependent.