In this paper, experimental tests conducted on a new wood-based air-heating system for energy-eff... more In this paper, experimental tests conducted on a new wood-based air-heating system for energy-efficient dwellings are presented. The main objective is to evaluate the resulting outlet temperatures and the amount of heat recovered by the ventilation air in order to assess feasibility and performance of coupling a mechanical ventilation heat-recovery unit and a triple concentric tube heat exchanger integrated into the chimney of a room-sealed wood-pellet stove to heat an entire house. After introducing the context of this work, the three main components of the combined system developed here, the coupling configuration adopted, as well as the protocol used and the sensors implemented on an experimental setup carried out in a laboratory are detailed in turn. Then, the heat transfer rates obtained from measurements for the various fluids as well as the effectiveness of the heat exchangers are presented and discussed. Finally, the resulting outlet temperatures of the three fluids exchanging in the triple concentric tube heat exchanger studied here are compared to those provided by analytical solutions obtained with a mathematical model. It is shown that heat transfer rates are predicted with a relative difference that is lower than 5% compared to experimental values and that such a system enables to cover all or most of heat losses in an energy efficient building.
In the present study, the relevance of a flue gas heat exchanger (FGHE) located at the exit of a ... more In the present study, the relevance of a flue gas heat exchanger (FGHE) located at the exit of a wood-log or a pellet stove to pre-heat ventilation air has been evaluated for energy-efficient single-family houses equipped with balanced mechanical ventilation. Thermal comfort and energy use have been compared with and without the system. In this prospect, dynamic thermal simulations (TRNSYS coupled with TRNFLOW) have been carried out on both a Norwegian detached house typology (passive house standard NS3700) and on a French detached house typology (building regulation RT2012), using 2 different climates corresponding to Oslo (cold climate) and La Rochelle (mixed climate). The results from the simulations show an operative temperature increase in the bedroom furthest away from the stove: up to 6.9°C of the 5th percentile of the operative temperature (Top 5%) for France and up to 4.3°C for Norway, compared to the same houses without the system. Moreover, energy savings of up to 18% were reported over the space-heating season compared to a conventional house without the tested system, depending on the control applied during operation.
This paper presents a summary of the main developments and results achieved in the frame-work of ... more This paper presents a summary of the main developments and results achieved in the frame-work of the French research project called EVAL-SDS. This project aims to analyse the performance of Natural, i.e. without use of fan for extraction, Soil Depressurization Systems (NSDS) to protect the built indoor environment from soil gaseous pollutant (Radon, Volatile Organic Compounds…). In this paper, the aeraulic performance of NSDS is studied i.e. its capacity to extract air from the ground to protect building’s occupants. To this end, we first performed measurements of airflow rates extracted by a NSDS integrated in a test-house during one year. Those data include various weather conditions (stack effect, wind) for several key parameters (wind extractor type, slab air permeability and basement pressure). Then, a dedicated calculation tool has been developed and validated against the experimental results. This numerical model has been used to evaluate the NSDS performance in France for di...
The performance of an innovative flue gas heat exchanger (FGHE) located at the exit of a woodburn... more The performance of an innovative flue gas heat exchanger (FGHE) located at the exit of a woodburning stove (log or pellet) to pre-heat ventilation air has been assessed for highly insulated detached houses. For this purpose, transient thermal simulations (TRNSYS+TRNFlow) were carried out on a Norwegian house typology (passive house standard NS3700) and a French house typology (building regulation RT2012) both equipped with mechanical ventilation systems with heat recovery (MVHR). Seven different climates were considered ranging from mixed (Nice, France) to subarctic conditions (Karasjok, Norway) in order to evaluate the impact of the system in terms of energy use for space-heating and thermal comfort for a broad range of operating conditions. The tested system allowed an improvement of the thermal comfort in the bedrooms furthest away from the stove: up to 7.6°C of the 5th percentile of the operative temperature (Top 5%) for France and up to 9.5°C for Norway, compared to the houses without the system. Furthermore, energy savings of up to 19% over the space-heating season were reported, depending on the type of wood-burning stove (i.e. log or pellet) and control used during operation.
Ce travail de thèse a été réalisé dans sa majeure partie au sein du Laboratoire d'Étude des Phéno... more Ce travail de thèse a été réalisé dans sa majeure partie au sein du Laboratoire d'Étude des Phénomènes de Transfert et de l'Instantanéité : Agro-industrie et Bâtiment (LEPTIAB) de l'Université de La Rochelle, devenu depuis le 1 er janvier 2012 le Laboratoire des Sciences de l'Ingénieur pour l'Environnement (LaSIE). Les essais expérimentaux en laboratoire ont quant à eux été menés en collaboration avec l'industriel POUJOULAT dans les locaux du Centre d'Essais et de Recherche des Industries de la Cheminée (CERIC) à Saint-Symphorien près de Niort. Je tiens tout d'abord à remercier les responsables de ces deux structures, Francis ALLARD au LEPTIAB et Lionel DRUETTE au CERIC, pour m'avoir accueilli et accordé leur confiance tout au long de ce travail. Ces remerciements s'étendent ensuite naturellement à l'ensemble des personnels administratifs et techniques qui animent ces structures et dont j'ai eu plaisir à croiser la route. Pour m'avoir suivi, conseillé et encouragé, j'exprime toute ma reconnaissance à mon directeur de thèse, Christian INARD et au responsable industriel du projet, Lionel DRUETTE. Je tiens à associer à ces remerciements Christophe MÉNÉZO et Gilles FRAISSE, qui m'ont fait l'honneur d'expertiser ce travail de thèse en tant que rapporteurs, ainsi que Joseph VIRGONE, Lionel DRUETTE et Francis ALLARD, qui m'ont également fait l'honneur de participer au jury de ces travaux. Mes remerciements les plus sincères s'adressent ensuite à toute l'équipe du CERIC avec un clin d'oeil appuyé à Pierre, Jérôme, Anne-Sandrine, Julien, Francis et Nicolas. Merci aussi à Laurence ROBERT pour son soutien précieux lors des premières années de ce projet et pour sa bienveillance en toute occasion. À tous les membres du LEPTIAB, permanents et doctorants, avec lesquels j'ai pu échanger, me détendre et apprendre, souvent autour d'un café… je vous remercie et je vous souhaite une bonne route à tous, avec l'espoir de vous retrouver tantôt par hasard, tantôt par vouloir... J'associe bien évidemment à ces remerciements, l'ensemble des personnes avec lesquelles j'ai eu l'occasion de travailler, notamment Oliver et Michel qui m'ont guidé dans les réalisations expérimentales. À mes collègues et amis, Marx et Adrien, merci pour vos épaules solides ! Certes, une thèse est un projet personnel, mais elle n'avait de sens pour moi que si je pouvais la partager. Merci de m'avoir accompagné sur ce chapitre de vie, tant au niveau professionnel que personnel… la suite de l'histoire nous appartient et j'ai hâte d'en écrire de nouvelles pages à vos côtés. Merci ! Enfin et surtout, toute ma gratitude s'adresse à ceux qui m'ont toujours soutenu, accompagné et conseillé alors que j'étais parfois en proie à de nombreuses interrogations. Merci. À ma famille, mes piliers, À toi Laurence, ma moitié, Et à l'avenir… au(x) bébé(s) ! Study of a wood-based heating system combined with a heat recovery ventilation in low energy buildings
This paper presents a new air-heating system concept for energy-efficient dwellings. It is a syst... more This paper presents a new air-heating system concept for energy-efficient dwellings. It is a system designed to heat a low-energy building by coupling a heat-recovery ventilation system with a three-fluid heat exchanger located on the chimney of a wood-pellet stove. The proposed work focuses on the heat transfer that occurs between flue gases, the ventilation air and the combustion air within a triple concentric tube heat exchanger with no insulation at its outer surface. The main objective is to predict outlet temperature for the specific geometry of the heat exchanger studied here. Thus, the governing differential equations are derived for a counter-co-current flow arrangement of the three fluids. Then analytical solutions for the steady-state temperature distribution are obtained as well as the amount of heat transferred to the outside. An expression for the effectiveness of the heat exchanger is also proposed. Based on these results, calculations are performed on a case study to predict the fluid temperature distribution along the heat exchanger. Finally, a parametric study is carried out on this case study to assess the influence of the relevant parameters on the effectiveness of the heat exchanger. In addition, computation of heat losses to the outside justifies whether insulation is needed.
In this paper, experimental tests conducted on a new wood-based air-heating system for energy-eff... more In this paper, experimental tests conducted on a new wood-based air-heating system for energy-efficient dwellings are presented. The main objective is to evaluate the resulting outlet temperatures and the amount of heat recovered by the ventilation air in order to assess feasibility and performance of coupling a mechanical ventilation heat-recovery unit and a triple concentric tube heat exchanger integrated into the chimney of a room-sealed wood-pellet stove to heat an entire house. After introducing the context of this work, the three main components of the combined system developed here, the coupling configuration adopted, as well as the protocol used and the sensors implemented on an experimental setup carried out in a laboratory are detailed in turn. Then, the heat transfer rates obtained from measurements for the various fluids as well as the effectiveness of the heat exchangers are presented and discussed. Finally, the resulting outlet temperatures of the three fluids exchanging in the triple concentric tube heat exchanger studied here are compared to those provided by analytical solutions obtained with a mathematical model. It is shown that heat transfer rates are predicted with a relative difference that is lower than 5% compared to experimental values and that such a system enables to cover all or most of heat losses in an energy efficient building.
In this paper, experimental tests conducted on a new wood-based air-heating system for energy-eff... more In this paper, experimental tests conducted on a new wood-based air-heating system for energy-efficient dwellings are presented. The main objective is to evaluate the resulting outlet temperatures and the amount of heat recovered by the ventilation air in order to assess feasibility and performance of coupling a mechanical ventilation heat-recovery unit and a triple concentric tube heat exchanger integrated into the chimney of a room-sealed wood-pellet stove to heat an entire house. After introducing the context of this work, the three main components of the combined system developed here, the coupling configuration adopted, as well as the protocol used and the sensors implemented on an experimental setup carried out in a laboratory are detailed in turn. Then, the heat transfer rates obtained from measurements for the various fluids as well as the effectiveness of the heat exchangers are presented and discussed. Finally, the resulting outlet temperatures of the three fluids exchanging in the triple concentric tube heat exchanger studied here are compared to those provided by analytical solutions obtained with a mathematical model. It is shown that heat transfer rates are predicted with a relative difference that is lower than 5% compared to experimental values and that such a system enables to cover all or most of heat losses in an energy efficient building.
In the present study, the relevance of a flue gas heat exchanger (FGHE) located at the exit of a ... more In the present study, the relevance of a flue gas heat exchanger (FGHE) located at the exit of a wood-log or a pellet stove to pre-heat ventilation air has been evaluated for energy-efficient single-family houses equipped with balanced mechanical ventilation. Thermal comfort and energy use have been compared with and without the system. In this prospect, dynamic thermal simulations (TRNSYS coupled with TRNFLOW) have been carried out on both a Norwegian detached house typology (passive house standard NS3700) and on a French detached house typology (building regulation RT2012), using 2 different climates corresponding to Oslo (cold climate) and La Rochelle (mixed climate). The results from the simulations show an operative temperature increase in the bedroom furthest away from the stove: up to 6.9°C of the 5th percentile of the operative temperature (Top 5%) for France and up to 4.3°C for Norway, compared to the same houses without the system. Moreover, energy savings of up to 18% were reported over the space-heating season compared to a conventional house without the tested system, depending on the control applied during operation.
This paper presents a summary of the main developments and results achieved in the frame-work of ... more This paper presents a summary of the main developments and results achieved in the frame-work of the French research project called EVAL-SDS. This project aims to analyse the performance of Natural, i.e. without use of fan for extraction, Soil Depressurization Systems (NSDS) to protect the built indoor environment from soil gaseous pollutant (Radon, Volatile Organic Compounds…). In this paper, the aeraulic performance of NSDS is studied i.e. its capacity to extract air from the ground to protect building’s occupants. To this end, we first performed measurements of airflow rates extracted by a NSDS integrated in a test-house during one year. Those data include various weather conditions (stack effect, wind) for several key parameters (wind extractor type, slab air permeability and basement pressure). Then, a dedicated calculation tool has been developed and validated against the experimental results. This numerical model has been used to evaluate the NSDS performance in France for di...
The performance of an innovative flue gas heat exchanger (FGHE) located at the exit of a woodburn... more The performance of an innovative flue gas heat exchanger (FGHE) located at the exit of a woodburning stove (log or pellet) to pre-heat ventilation air has been assessed for highly insulated detached houses. For this purpose, transient thermal simulations (TRNSYS+TRNFlow) were carried out on a Norwegian house typology (passive house standard NS3700) and a French house typology (building regulation RT2012) both equipped with mechanical ventilation systems with heat recovery (MVHR). Seven different climates were considered ranging from mixed (Nice, France) to subarctic conditions (Karasjok, Norway) in order to evaluate the impact of the system in terms of energy use for space-heating and thermal comfort for a broad range of operating conditions. The tested system allowed an improvement of the thermal comfort in the bedrooms furthest away from the stove: up to 7.6°C of the 5th percentile of the operative temperature (Top 5%) for France and up to 9.5°C for Norway, compared to the houses without the system. Furthermore, energy savings of up to 19% over the space-heating season were reported, depending on the type of wood-burning stove (i.e. log or pellet) and control used during operation.
Ce travail de thèse a été réalisé dans sa majeure partie au sein du Laboratoire d'Étude des Phéno... more Ce travail de thèse a été réalisé dans sa majeure partie au sein du Laboratoire d'Étude des Phénomènes de Transfert et de l'Instantanéité : Agro-industrie et Bâtiment (LEPTIAB) de l'Université de La Rochelle, devenu depuis le 1 er janvier 2012 le Laboratoire des Sciences de l'Ingénieur pour l'Environnement (LaSIE). Les essais expérimentaux en laboratoire ont quant à eux été menés en collaboration avec l'industriel POUJOULAT dans les locaux du Centre d'Essais et de Recherche des Industries de la Cheminée (CERIC) à Saint-Symphorien près de Niort. Je tiens tout d'abord à remercier les responsables de ces deux structures, Francis ALLARD au LEPTIAB et Lionel DRUETTE au CERIC, pour m'avoir accueilli et accordé leur confiance tout au long de ce travail. Ces remerciements s'étendent ensuite naturellement à l'ensemble des personnels administratifs et techniques qui animent ces structures et dont j'ai eu plaisir à croiser la route. Pour m'avoir suivi, conseillé et encouragé, j'exprime toute ma reconnaissance à mon directeur de thèse, Christian INARD et au responsable industriel du projet, Lionel DRUETTE. Je tiens à associer à ces remerciements Christophe MÉNÉZO et Gilles FRAISSE, qui m'ont fait l'honneur d'expertiser ce travail de thèse en tant que rapporteurs, ainsi que Joseph VIRGONE, Lionel DRUETTE et Francis ALLARD, qui m'ont également fait l'honneur de participer au jury de ces travaux. Mes remerciements les plus sincères s'adressent ensuite à toute l'équipe du CERIC avec un clin d'oeil appuyé à Pierre, Jérôme, Anne-Sandrine, Julien, Francis et Nicolas. Merci aussi à Laurence ROBERT pour son soutien précieux lors des premières années de ce projet et pour sa bienveillance en toute occasion. À tous les membres du LEPTIAB, permanents et doctorants, avec lesquels j'ai pu échanger, me détendre et apprendre, souvent autour d'un café… je vous remercie et je vous souhaite une bonne route à tous, avec l'espoir de vous retrouver tantôt par hasard, tantôt par vouloir... J'associe bien évidemment à ces remerciements, l'ensemble des personnes avec lesquelles j'ai eu l'occasion de travailler, notamment Oliver et Michel qui m'ont guidé dans les réalisations expérimentales. À mes collègues et amis, Marx et Adrien, merci pour vos épaules solides ! Certes, une thèse est un projet personnel, mais elle n'avait de sens pour moi que si je pouvais la partager. Merci de m'avoir accompagné sur ce chapitre de vie, tant au niveau professionnel que personnel… la suite de l'histoire nous appartient et j'ai hâte d'en écrire de nouvelles pages à vos côtés. Merci ! Enfin et surtout, toute ma gratitude s'adresse à ceux qui m'ont toujours soutenu, accompagné et conseillé alors que j'étais parfois en proie à de nombreuses interrogations. Merci. À ma famille, mes piliers, À toi Laurence, ma moitié, Et à l'avenir… au(x) bébé(s) ! Study of a wood-based heating system combined with a heat recovery ventilation in low energy buildings
This paper presents a new air-heating system concept for energy-efficient dwellings. It is a syst... more This paper presents a new air-heating system concept for energy-efficient dwellings. It is a system designed to heat a low-energy building by coupling a heat-recovery ventilation system with a three-fluid heat exchanger located on the chimney of a wood-pellet stove. The proposed work focuses on the heat transfer that occurs between flue gases, the ventilation air and the combustion air within a triple concentric tube heat exchanger with no insulation at its outer surface. The main objective is to predict outlet temperature for the specific geometry of the heat exchanger studied here. Thus, the governing differential equations are derived for a counter-co-current flow arrangement of the three fluids. Then analytical solutions for the steady-state temperature distribution are obtained as well as the amount of heat transferred to the outside. An expression for the effectiveness of the heat exchanger is also proposed. Based on these results, calculations are performed on a case study to predict the fluid temperature distribution along the heat exchanger. Finally, a parametric study is carried out on this case study to assess the influence of the relevant parameters on the effectiveness of the heat exchanger. In addition, computation of heat losses to the outside justifies whether insulation is needed.
In this paper, experimental tests conducted on a new wood-based air-heating system for energy-eff... more In this paper, experimental tests conducted on a new wood-based air-heating system for energy-efficient dwellings are presented. The main objective is to evaluate the resulting outlet temperatures and the amount of heat recovered by the ventilation air in order to assess feasibility and performance of coupling a mechanical ventilation heat-recovery unit and a triple concentric tube heat exchanger integrated into the chimney of a room-sealed wood-pellet stove to heat an entire house. After introducing the context of this work, the three main components of the combined system developed here, the coupling configuration adopted, as well as the protocol used and the sensors implemented on an experimental setup carried out in a laboratory are detailed in turn. Then, the heat transfer rates obtained from measurements for the various fluids as well as the effectiveness of the heat exchangers are presented and discussed. Finally, the resulting outlet temperatures of the three fluids exchanging in the triple concentric tube heat exchanger studied here are compared to those provided by analytical solutions obtained with a mathematical model. It is shown that heat transfer rates are predicted with a relative difference that is lower than 5% compared to experimental values and that such a system enables to cover all or most of heat losses in an energy efficient building.
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