Publications of Pierre Dewallef
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See detailExperimental validation of heat transport modeling in large solar thermal plant.
Sartor, Kevin ULiege; Dickes, Rémi ULiege; Resimont, Thibaut ULiege et al

Conference (2018, June)

Solar thermal plants are often considered as a convenient and environmental-friendly way to supply heat to buildings or low temperature industrial processes. Some modelling techniques are required to ... [more ▼]

Solar thermal plants are often considered as a convenient and environmental-friendly way to supply heat to buildings or low temperature industrial processes. Some modelling techniques are required to assess the dynamic behaviour of solar thermal plants in order to control them correctly. This aspect is reinforced while large plants are considered. Indeed some atmospheric conditions as local clouds could have significant influence on the outlet temperature of the solar field. A common modelling approach to assess the heat transport in pipes is the one-dimensional finite volume method. However previous work shows limitations in the assessment of the temperatures and in the computational time require simulating large pipe networks. In this contribution, a previous alternative method developed and validated in a district heating network is used and extended to a solar thermal plant considering the thermal solar gain and the inertia of the pipes. The present contribution intends to experimentally validate this model on an existing solar plant facility available at the Plataforma Solar de Almeria in Spain. [less ▲]

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See detailThermo-Economic Evaluation of a Virtual District Heating Network Using Dynamic Simulation
Resimont, Thibaut ULiege; Sartor, Kevin ULiege; Dewallef, Pierre ULiege

Scientific conference (2018, June)

In the current context of energy transition, district heating systems are considered as a convenient yet efficient solution to reduce both primary energy consumption and greenhouse gases emissions. The ... [more ▼]

In the current context of energy transition, district heating systems are considered as a convenient yet efficient solution to reduce both primary energy consumption and greenhouse gases emissions. The use of locally available alternative heat sources, as for example the heat rejected by waste incinerators, constitutes an opportunity to valorize low-grade heat. Despite a higher initial investment cost, waste incinerators present the advantage to have a zero fuel cost that balances this initial capital expense. In the present contribution, a reference case study based on the IEA EBC Annex 60 framework is used as a first attempt to explore dynamic effects related to the distribution of heat through district heating networks. It consists of a small set of reference dwellings with different heating profiles depending on the type of buildings and their level of insulation. The costs for the different operating scenarios and the consequent advantages of a combined heat and power waste incinerator as a heat source are determined. This paper illustrates the use of a plug flow dynamic model intended to predict the heat transport delay, the heat losses and the pumping work due to long piping instead of the classical steady-state approach usually used for district heating networks profitability assessment. A comparative assessment of both the unit cost of heat and CO2 emissions savings is performed for two different heating technologies, namely a combined heat and power waste incinerator combined to backup boilers and a natural gas boiler. [less ▲]

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See detailA comparative study for simulating heat transport in large district heating networks
Sartor, Kevin ULiege; Thomas, David ULiege; Dewallef, Pierre ULiege

in International Journal of Heat and Technology (2018), 36(1), 301--308

District heating networks are a convenient, economic and environmental-friendly way to supply heat to buildings connected to a central heating plant. However, the control of such a system becomes ... [more ▼]

District heating networks are a convenient, economic and environmental-friendly way to supply heat to buildings connected to a central heating plant. However, the control of such a system becomes challenging if the total length of the network reaches several kilometers because the travel time of the information into the system is over hours. One solution consists in instrumenting all the parts of the network and performing a closed loop control to optimize the temperature and the mass flow rate supplied to every single consumption point. However this solution is generally expensive and difficult to implement in existing networks. What is proposed in this paper is to dynamically model the heat waves in the network to determine the temperatures and mass flow rates at key locations considering the ambient losses and the pipe thermal inertia. A study is performed to check the possibility to use the one-dimensional finite volume method to simulate heat waves propagation. First, an adiabatic pipe is considered as a reference test case to determine the limitations of this method. The results are compared to a 2D computational fluid dynamic simulation and numerical diffusion is exhibited for low spatial discretization. Therefore, an improved alternative model is developed to overcome this problem. [less ▲]

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See detailIntegration of heat storage system into district heating networks fed by a biomass CHP plant
Sartor, Kevin ULiege; Dewallef, Pierre ULiege

in Journal of Energy Storage (2018), 15

Biomass Combined Heat and Power (CHP) plants connected to district heating networks (DHN) are recognized as a very good opportunity to increase the share of renewable sources into energy systems. However ... [more ▼]

Biomass Combined Heat and Power (CHP) plants connected to district heating networks (DHN) are recognized as a very good opportunity to increase the share of renewable sources into energy systems. However, as CHP plants are not optimized for electricity production, their operation is profitable only if a sufficient heat demand is available throughout the year. On the other hand, these plants often work for baseline operations and back-up boilers are used to supply the peak demand. To extend the use of the CHP plants and reduce costs, conventional fuel use and emissions, it is proposed to study the feasibility of using the DHN itself or additional high temperature heat storage as retrofit of an existing CHP plant. This work is based on a simple and effective methodology that provides accurate estimations of economic, environmental and energetic performances of CHP plants connected to district heating networks. The focus is performed on the integration of the heat storage as retrofit of existing DHN considering the local policies. The DHN of the University in Liège (Belgium) is used as an application framework to demonstrate the effectiveness of the selected approach. The potential energy, pollutant emissions savings and resulting energy costs are estimated and the current policy limitations will be discussed. [less ▲]

Detailed reference viewed: 37 (7 ULiège)
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See detailExperimental validation of heat transport modelling in district heating networks.
Sartor, Kevin ULiege; Dewallef, Pierre ULiege

in Energy (2017), 137

District heating networks (DHN) are generally considered as a convenient, economic and environmental-friendly way to supply heat to a large amount of buildings. Some modelling methods are required to ... [more ▼]

District heating networks (DHN) are generally considered as a convenient, economic and environmental-friendly way to supply heat to a large amount of buildings. Some modelling methods are required to consider the dynamic behaviour of district heating networks to design them correctly, spare the investment costs and limit the heat losses related to the use of a too high operating temperatures. For the same reasons, the DHN control or retrofit of installations also requires the assessment of the DHN dynamic behaviour. To achieve this, the heat transport in DHN, which is one of the key issues in the behaviour of a whole centralized heating system, has to be correctly modelled. Previous work evidenced current limitations of one dimensional finite volume method to model heat transport in pipes and proposed an alternative method considering the thermal losses and the inertia of the pipes. The present contribution intends to experimentally validate this model on a test rig available at the Thermodynamics laboratory of the University of Liège (ULg, Belgium) and on an existing district heating network. For both experimental facilities, the current model shows good agreement between the experimental data and the simulation results for a large range of water velocities. Moreover, it is shown that the thermal inertia of the pipe has a significant influence on the outlet pipe temperature profile. [less ▲]

Detailed reference viewed: 91 (24 ULiège)
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See detailExergy analysis applied to performance of buildings in Europe
Sartor, Kevin ULiege; Dewallef, Pierre ULiege

in Energy and Buildings (2017), 148

Energy performance of buildings generally assesses the energy consumption of buildings such as heating, domestic heat water, ventilation systems, etc. However, this approach is based on the first law of ... [more ▼]

Energy performance of buildings generally assesses the energy consumption of buildings such as heating, domestic heat water, ventilation systems, etc. However, this approach is based on the first law of thermodynamics and considers only the quantity of energy used without considering its ‘quality’ and leads to a lack of information about the energy conversion processes. This is particularly true in the new low-energy buildings where sometimes high temperatures sources are used to meet low-temperature needs. The exergy analysis of a system, based on first and second thermodynamic laws, can be used to overcome this. In this work, it is proposed to compare the energy and the exergy consumption and the related CO2 emissions of several kinds of buildings to determine the best systems in terms of energy and exergy needs. The energy demand calculations are performed using the official software available in Belgium and some assumptions are implemented to consider the exergy approach. As exergy calculations require a reference state, some different climatic conditions are also investigated. Finally, some conclusions are discussed to rank the sources of energy and their related exergy losses. [less ▲]

Detailed reference viewed: 55 (17 ULiège)
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See detailImproved district heating network operation by the integration of high-temperature heat pumps
Sartor, Kevin ULiege; Lemort, Vincent ULiege; Dewallef, Pierre ULiege

in International Journal of Sustainable Energy (2017)

Biomass combined heat and power (CHP) plants connected to district heating networks are a very good opportunity to increase the share of renewable sources into energy systems. Frequently, important ... [more ▼]

Biomass combined heat and power (CHP) plants connected to district heating networks are a very good opportunity to increase the share of renewable sources into energy systems. Frequently, important consumers are connected to ensure a stable base heat demand throughout the year but they often have higher requirements in terms of temperature (i.e. steam), which involves a high level of temperature in the district heating network during the whole year and high levels of heat losses in the network. This contribution presents the possibility to decrease the level of temperature at which the district heating network operates and to use high-temperature heat pumps connected locally at the consumption point to produce steam when it is required. An investigation of the global design and integration through thermodynamic simulation models is realised for the University of Liège district heating network. This study is intended to determine the heat pump coefficient of performance and, therefore, to assess the balance between the savings in terms of heat losses and the additional heat pump electricity consumption. © 2017 Informa UK Limited, trading as Taylor & Francis Group [less ▲]

Detailed reference viewed: 42 (12 ULiège)
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See detailEffect of undisturbed ground temperature on the design of closed-loop geothermal systems: A case study in a semi-urban environment
Radioti, Georgia ULiege; Sartor, Kevin ULiege; Charlier, Robert ULiege et al

in Applied Energy (2017)

This paper presents temperature measurements in four Borehole Heat Exchangers (BHEs), equipped with fiber optics and located in a semi-urban environment (campus of the University of Liege, Belgium). A 3D ... [more ▼]

This paper presents temperature measurements in four Borehole Heat Exchangers (BHEs), equipped with fiber optics and located in a semi-urban environment (campus of the University of Liege, Belgium). A 3D numerical model is also presented to simulate the heat loss from the surrounding structures into the subsurface. The mean undisturbed ground temperature was estimated from data during the preliminary phase of a thermal response test (water circulation in the pipe loops), as well as from borehole logging measurements. The measurements during water circulation can significantly overestimate the ground temperature (up to 1.7 C in this case study) for high ambient air temperature during the test, resulting in an overestimation of the maximum extracted power and of the heat pump coefficient of performance (COP). To limit the error in the COP and the extracted power to less than 5%, the error in the undisturbed temperature estimation should not exceed ±1.5 °C and ±0.6 °C respectively. In urbanised areas, configurations of short BHEs (length < 40 m) could be economically advantageous (decreased installation and operation costs) compared to long BHEs, especially for temperature gradient lower than 0.05 °C/m. [less ▲]

Detailed reference viewed: 48 (13 ULiège)
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See detailRegression-Based Modeling of a Fleet of Gas Turbine Engines for Performance Trending
Borguet, Sébastien ULiege; Dewallef, Pierre ULiege; Leonard, Olivier

in Journal of Engineering for Gas Turbines and Power (2016), 138(2), 021201

Module performance analysis is a well-established framework to assess changes in the health condition of the components of the engine gas-path. The primary material of the technique is the so-called ... [more ▼]

Module performance analysis is a well-established framework to assess changes in the health condition of the components of the engine gas-path. The primary material of the technique is the so-called vector of residuals, which are built as the difference between actual measurement taken in the gas-path and values predicted by means of an engine model. Obviously, the quality of the assessment of the engine condition depends strongly on the accuracy of the engine model. The present paper proposes a new approach for data-driven modelling of a fleet of engines of a given type. Such black-box models can be designed by operators such as airlines and third-party companies. The fleet-wide modelling process is formulated as a regression problem that provides a dedicated model for each engine in the fleet, while recognising that all engines are of the same type. The methodology is applied to a virtual fleet of engines generated within the ProDiMES environment. The set of models is assessed quantitatively through the coefficient of determination and is further used to perform anomaly detection. [less ▲]

Detailed reference viewed: 25 (2 ULiège)
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See detailExergy analysis applied to performance of buildings in Europe
Sartor, Kevin ULiege; Dewallef, Pierre ULiege

in Proceedings (2016)

Energy performance of buildings generally assesses the energy consumption of buildings such as heating, domestic heat water, ventilation systems... However, this approach is based on the first law of ... [more ▼]

Energy performance of buildings generally assesses the energy consumption of buildings such as heating, domestic heat water, ventilation systems... However, this approach is based on the first law of thermodynamics and considers only the quantity of energy used without considering its “quality” and leads to a lack of information about the energy conversion processes. This is particularly true in the new low-energy buildings where sometimes high temperatures sources are used to meet low-temperature needs. The exergy analysis of a system, based on first and second thermodynamic laws, can be used to overcome this. In this work, it is proposed to compare the energy and the exergy consumption of several kinds of buildings to determine the best systems in terms of energy and exergy needs. The energy demand calculations are performed using the official software available in Belgium and some assumptions are implemented to consider the exergy approach. As exergy calculations require a reference state, some different climatic conditions are also investigated. Finally, some conclusions are discussed to rank the sources of energy and their related exergy losses. [less ▲]

Detailed reference viewed: 36 (8 ULiège)
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See detailExergetic, environmental and economic analysis of a biomass cogeneration plant connected to a district heating network.
Sartor, Kevin ULiege; Dewallef, Pierre ULiege

in Renewable Energy in the Service of Mankind Vol II (2015)

When a district heating network is fed by natural gas boilers (or biomass boilers), the selection of the network temperature level has a slight influence on the boiler efficiency which means that ... [more ▼]

When a district heating network is fed by natural gas boilers (or biomass boilers), the selection of the network temperature level has a slight influence on the boiler efficiency which means that producing at low temperature allows only to decrease the heat losses through the network. However when a cogeneration plant based on a Rankine cycle is used, lowering the network temperature not only decreases the heat losses but also increase the electrical efficiency while decreasing the thermal efficiency. This aspect is very often overlooked when the quality of a cogeneration plant is assessed by the cogeneration efficiency namely the sum of the electrical and thermal efficiency which is misleading for decision makers. In this contribution, an existing cogeneration plant connected to a district heating network installed on the University Campus in Liège (Belgium) is used as an application test case. Based on actual operational and economic data, a detailed economic evaluation is carried out which is supported by a calibrated simulation model of the whole installation in order to study the influence of the network temperature level. As a second step, the simulation model is used again to perform a detailed exergetic analysis intended to give physical insights to the economical study. This results in a broader discussion on the several methods to assess the quality of cogeneration plants and the opportunity to develop such a technology together with district heating networks. [less ▲]

Detailed reference viewed: 88 (15 ULiège)
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See detailA comparative study for simulating heat transport in large district heating network
Sartor, Kevin ULiege; Thomas, David ULiege; Dewallef, Pierre ULiege

in Proceedings of ECOS 2015 (2015, June 29)

Detailed reference viewed: 199 (39 ULiège)
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See detailRegression-based modelling of a fleet of gas turbine engines for performance trending
Borguet, Sébastien ULiege; Léonard, Olivier ULiege; Dewallef, Pierre ULiege

in Proceedings of ASME Turbo Expo 2015 (2015, June)

Module performance analysis is a well-established framework to assess changes in the health condition of the components of the engine gas-path. The primary material of the technique is the so-called ... [more ▼]

Module performance analysis is a well-established framework to assess changes in the health condition of the components of the engine gas-path. The primary material of the technique is the so-called vector of residuals, which are built as the difference between actual measurement taken in the gas-path and values predicted by means of an engine model. Obviously, the quality of the assessment of the engine condition depends strongly on the accuracy of the engine model. The present paper proposes a new approach for data-driven modelling of a fleet of engines of a given type. Such black-box models can be designed by operators such as airlines and thirdparty companies. The fleet-wide modelling process is formulated as a regression problem that provides a dedicated model for each engine in the fleet, while recognising that all engines are of the same type. The methodology is applied to a virtual fleet of engines generated within the ProDiMES environment. The set of models is assessed quantitatively through the coefficient of determination and is further used to perform anomaly detection. [less ▲]

Detailed reference viewed: 65 (4 ULiège)
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See detailAnalysis versus synthesis for trending gas-path measurement time series
Borguet, Sébastien ULiege; Léonard, Olivier ULiege; Dewallef, Pierre ULiege

in Journal of Engineering for Gas Turbines and Power (2015), 137

Gas-path measurements used to assess the health condition of an engine are corrupted by noise. Generally, a data cleaning step occurs before proceeding with fault detection and isolation. Classical linear ... [more ▼]

Gas-path measurements used to assess the health condition of an engine are corrupted by noise. Generally, a data cleaning step occurs before proceeding with fault detection and isolation. Classical linear filters such as the EWMA filter are traditionally used for noise removal. Unfortunately, these low-pass filters distort trend shifts indicative of faults, which increases the detection delay. The present paper investigates two new approaches to nonlinear filtering of time series. On the one hand, the synthesis approach reconstructs the signal as a combination of elementary signals chosen from a predefined library. On the other hand, the analysis approach imposes a constraint on the shape of the signal (e.g., piecewise constant). Both approaches incorporate prior information about the signal in a different way, but they lead to trend filters that are very capable at noise removal while preserving at the same time sharp edges in the signal. This is highlighted through the comparison with a classical linear filter on a batch of synthetic data representative of typical engine fault profiles. [less ▲]

Detailed reference viewed: 27 (2 ULiège)
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See detailSimulation and optimization of a CHP biomass plant and district heating network
Sartor, Kevin ULiege; Quoilin, Sylvain ULiege; Dewallef, Pierre ULiege

in Applied Energy (2014), 130

Biomass Combined Heat and Power (CHP) plants connected to district heating (DH) networks are recognized nowadays as a very good opportunity to increase the share of renewable sources into energy systems ... [more ▼]

Biomass Combined Heat and Power (CHP) plants connected to district heating (DH) networks are recognized nowadays as a very good opportunity to increase the share of renewable sources into energy systems. However, as CHP plants are not optimized for electricity production, their operation is profitable only if a sufficient heat demand is available throughout the year. Most of the time, pre-feasibility studies are based on peak power demand and business plans only assume monthly or yearly consumption data. This approach usually turns out to overestimate the number of operating hours or oversize the plant capacity. This contribution presents a methodology intended to be simple and effective that provides accurate estimations of economical, environmental and energetic performances of CHP plants connected to district heating networks. A quasi-steady state simulation model of a CHP plant combined with a simulation model of the district heating network installed on the Campus of the University in Liège (Belgium) is used as an application framework to demonstrate the effectiveness of the selected approach. Based on the developed model and actual consumption data, several scenarios for energy savings are considered and ranked. The potential energy savings and resulting energy costs are estimated enabling more general conclusions to be drawn on the opportunity of using district heating networks in urban districts for Western Europe countries. [less ▲]

Detailed reference viewed: 185 (41 ULiège)
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See detailPrediction of SOx and NOx Emissions from a Medium Size Biomass Boiler Biomass and Bioenergy
Sartor, Kevin ULiege; Restivo, Yannick ULiege; Ngendakumana, Philippe ULiege et al

in Biomass and Bioenergy (2014), 65

While small and medium size biomass combined heat and power (CHP) plants (i.e., up to 5 MW of electrical rated power) represent an attractive option to exploit locally available biomass resources at low ... [more ▼]

While small and medium size biomass combined heat and power (CHP) plants (i.e., up to 5 MW of electrical rated power) represent an attractive option to exploit locally available biomass resources at low cost, the corresponding investment per unit of rated power significantly rises when the installed power decreases. In these cases, secondary pollutant emissions control measures are most of the time not economically viable and primary emissions control must be used alone to avoid the formation of undesired compounds such as $NO_x$ and $SO_x$. Primary control measures require the careful optimization of fuel quality and combustion process. For plant operators, being able to accommodate biomass quality changes in order to minimize the fuel cost can be of great importance in order to guarantee the profitability of the plant. This contribution is dedicated to the development of a zero-dimensional (input-output) combustion simulation model able to predict the pollutants emissions resulting from complete and incomplete combustion with respect to varying combustion operation (ambient temperature, humidity, fumes recirculation,..). This tool is intended to be integrated in a global simulation model of the CHP plant and the attached district heating network installed on the University campus in Liège. Doing so, the plant operation can be optimized with respect to economic as well as environmental and energetic aspects (3E approach) thus ensuring the sustainability of the approach. [less ▲]

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See detailAnalysis versus synthesis for trending of gas-path measurement time series
Borguet, Sébastien ULiege; Léonard, Olivier ULiege; Dewallef, Pierre ULiege

in Proceedings of ASME Turbo Expo 2014 (2014, June)

Gas-path measurements used to assess the health condition of an engine are corrupted by noise. Generally, a data cleaning step occurs before proceeding with fault detection and isolation. Classical linear ... [more ▼]

Gas-path measurements used to assess the health condition of an engine are corrupted by noise. Generally, a data cleaning step occurs before proceeding with fault detection and isolation. Classical linear filters such as the exponentially weighted moving average filter are traditionally used for noise removal. Unfortunately, these low-pass filters distort trend shifts indicative of faults, which increases the detection delay. The present paper investigates two new approaches to non-linear filtering of time series. On one hand, the synthesis approach reconstructs the signal as a combination of elementary signals chosen from a pre-defined library. On the other hand, the analysis approach imposes a constraint on the shape of the signal (e.g., piecewise constant). Both approaches incorporate prior information about the signal in a different way, but they lead to trend filters that are very capable at noise removal while preserving at the same time sharp edges in the signal. This is highlighted through the comparison with a classical linear filter on a batch of synthetic data representative of typical engine fault profiles. [less ▲]

Detailed reference viewed: 26 (5 ULiège)
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See detailMethods to Increase the Robustness of Finite-Volume Flow Models in Thermodynamic Systems
Quoilin, Sylvain ULiege; Bell, Ian ULiege; Desideri, Adriano ULiege et al

in Energies (2014), 7(3), 1621-1640

This paper addresses the issues linked to simulation failures during integration in finite-volume flow models, especially those involving a two-phase state. This kind of model is particularly useful when ... [more ▼]

This paper addresses the issues linked to simulation failures during integration in finite-volume flow models, especially those involving a two-phase state. This kind of model is particularly useful when modeling 1D heat exchangers or piping, e.g., in thermodynamic cycles involving a phase change. Issues, such as chattering or stiff systems, can lead to low simulation speed, instabilities and simulation failures. In the particular case of two-phase flow models, they are usually linked to a discontinuity in the density derivative between the liquid and two-phase zones. In this work, several methods to tackle numerical problems are developed, described, implemented and compared. In addition, methods available in the literature are also implemented and compared to the proposed approaches. Results suggest that the robustness of the models can be significantly increased with these different methods, at the price of a small increase of the error in the mass and energy balances. [less ▲]

Detailed reference viewed: 260 (31 ULiège)
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See detailUnveiling the mystery of Combined Heat & Power (cogeneration)
Verbruggen, Aviel; Dewallef, Pierre ULiege; Quoilin, Sylvain ULiege et al

in Energy (2013), 61

The article unveils the mystery of cogeneration. Cogeneration is an add-on or embedded activity in thermal power plants, with as merit the use of part or whole of their point source heat exhausts. EU's ... [more ▼]

The article unveils the mystery of cogeneration. Cogeneration is an add-on or embedded activity in thermal power plants, with as merit the use of part or whole of their point source heat exhausts. EU's talk of “high-efficiency cogeneration” is an unfounded transfer of responsibility from the hosting thermal power generation plant onto CHP (Combined Heat & Power) activity. The quality of a CHP activity is univocally defined by its design power-to-heat ratio σ, a tombstone parameter derived from the design characteristics of the power plant. A thermal power plant may house more than one cogeneration activity. Identifying σ requires positioning the bliss point in the electricity–heat production possibility set of the cogeneration activity. The bliss point is where after electric output is maximized, the sum of that output and the maximum recoverable quantity of heat occurs. Once CHP's mystery of virtual bliss points is unveiled, the proper σ are found. With known σ by CHP activity, the quantity of cogenerated electricity is reliably assessed as best indicator of cogeneration performance. Our analysis is applicable on all relevant thermal power cycles that host CHP activities, and illustrated with a numerical example. Our lean method is necessary and sufficient for proper CHP regulation. [less ▲]

Detailed reference viewed: 76 (10 ULiège)
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See detailImproved District Heating Network Operation by the Integration of High Temperature Heat Pumps
Sartor, Kevin ULiege; Lemort, Vincent ULiege; Dewallef, Pierre ULiege

in Digital proceedings of the 8th Conference on Sustainable Development of Energy, Water and Environment Systems - SDEWES (2013, September 23)

Biomass Combined Heat and Power (CHP) plants connected to district heating networks are a very good opportunity to increase the share of renewable sources into energy systems. Frequently, important ... [more ▼]

Biomass Combined Heat and Power (CHP) plants connected to district heating networks are a very good opportunity to increase the share of renewable sources into energy systems. Frequently, important consumers are connected to ensure a stable base demand of heat throughout the year but they often have higher requirements in terms of temperature (i.e., steam) which involves high level of temperatures in the district heating network during the whole year and high levels of heat losses in the network. This contribution presents the possibility to decrease the level of temperature at which the district heating network operates and to use high temperature heat pumps connected locally at the consumption point to produce steam when needed. An investigation of the global design and integration through thermodynamic simulation models is realized for the University of Liège district heating network. This study is intended to determine the heat pump coefficient of performance and, therefore, to assess the balance between the savings in terms of heat losses and the additional heat pump electricity consumption. [less ▲]

Detailed reference viewed: 103 (20 ULiège)