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Practical support for evaluating efficiency factors of a space heating system in cold climates: modelling and simulation of hydronic panel radiator with different location of connection pipes
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Energy Efficiency)ORCID iD: 0000-0002-2822-0000
EQUA simualtion.
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Energy Efficiency)
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Energy efficiency ; Arcum)
2017 (English)In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 10, no 5, p. 1253-1267Article in journal (Refereed) Published
Abstract [en]

Plenty of technical norms, included in the EPBD umbrella, assess the performance of buildings or its sub-systems in terms of efficiency. In particular, EN 15316 and its sub-sections, determine the system energy requirements and the system efficiencies of space heating system. This paper focuses on the estimation of efficiencies for emission of hydronic radiators. The assessment of efficiencies for emission occurs by evaluating the amount of heat emitted  from the heat emitter and the extra thermal losses towards building envelope. The heat emitted from radiators varies during the heating up/cooling down phases. A factor that influences the heat emitted during these phases is the location of connection pipes of the radiator. Connection pipes can be located on opposite side or at the same side of the radiator. To better estimate the heat emitted from radiators a transient model with multiple storage elements is used in a building simulation model. Sensitivity analysis encompasses all  the possible variations on extra thermal losses due to the building location in different climates, the heaviness of active thermal mass and the type of radiator local control. The final outcome of this paper is a practical support where the designer can easily assess the efficiencies for emission of hydronic radiators  for Swedish buildings. As main result, (i) the efficiency for control of space heating system is higher in Northern climates than in Southern climates, (ii) heavy active thermal masses allow higher efficiencies for emission than light active thermal masses, (iii) connection pipes located on the same side of the radiator enable higher efficiencies for emission than pipes located on opposite side.

Place, publisher, year, edition, pages
2017. Vol. 10, no 5, p. 1253-1267
Keywords [en]
Hydronic panel radiator, Efficiency factors, Connection pipes, Transient model with multiple storage elements, Climate, Active thermal mass
National Category
Building Technologies
Research subject
Systems Analysis
Identifiers
URN: urn:nbn:se:umu:diva-121199DOI: 10.1007/s12053-017-9506-7ISI: 000411865800013OAI: oai:DiVA.org:umu-121199DiVA, id: diva2:931578
Available from: 2016-05-29 Created: 2016-05-29 Last updated: 2018-09-25Bibliographically approved
In thesis
1. Modelling and simulation of building components: thermal interaction between multilayer wall and hydronic radiator
Open this publication in new window or tab >>Modelling and simulation of building components: thermal interaction between multilayer wall and hydronic radiator
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Background and Scope The scope of this thesis is to investigate the thermal behaviour of building components as hydronic radiator and multilayer walls subjected to dynamic conditions. The modelling and simulation of these building components provide information on how these components thermally interact among each other. The thermal interaction is fundamental to know how the energy is used in buildings. In particular, the thermal energy used in rooms can be expressed as the efficiencies for emission in a space heating system. This thesis analyzes the efficiencies for emission of a space heating system equipped with hydronic radiator for Swedish buildings by providing a comprehensive and detailed approach on this topic.

 

Methodology The methods used in this thesis are: experiment, modelling of multilayer wall and hydronic radiator, the dynamic simulation of the building and the efficiencies for emission of a space heating system. Here, the experiment, known as step response test, shows the heating up process of a hydronic radiator. The observation of the qualitative measurements suggests the most suitable technique of modelling the radiator known as transient modelling with multiple storage elements. The multilayer wall has been discretized both in space and time variable with a Finite Difference Method. Dynamic simulation of the building provides the efficiencies for emission of a space heating system.

 

Findings The experimental results show how the radiator performs the charging phase. The performance of the transient model is compared with lumped steady state models in terms of temperature of exhaust flow and total heat emitted. Results of the dynamic simulation show how buildings located in a Northern climate use the energy in a better way than Southern climates in Sweden. Heavy active thermal mass provides higher efficiencies for emission than light thermal mass. Radiators with connection pipes located on the same side react faster at the thermodynamic changing of the mass flow rate by providing higher efficiencies for emission than radiators with connection pipes located on the opposite side.

 

Conclusion and Outlook This thesis increases the knowledge about the modelling and simulation of hydronic radiators and multilayer walls. More research is needed on this topic to encompass modelling details of building components often ignored. The modelling and simulation of building components are the key to understand how building components thermally interact with each other. The thermal interaction among building components is a fundamental parameter for the assessment of efficiencies of emission of the space heating system. In the near future, the concept of efficiencies of emission can be implemented in National Building Code, therefore, this study provides guidelines on how to assess these efficiencies.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2016. p. 39
Keywords
Hydronic radiator, multilayer wall, efficiencies of emission
National Category
Building Technologies
Research subject
Systems Analysis; Technical Physics
Identifiers
urn:nbn:se:umu:diva-121201 (URN)978-91-7601-515-5 (ISBN)
Presentation
2016-06-15, MC413, MIT-huset, Umeå University, Umeå, 13:00 (English)
Opponent
Supervisors
Note

Advisors: Ronny Östin and Mohsen Soleimanni Mohseni, Department of Applied Physics and Electronics, Umeå University

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2018-06-07Bibliographically approved
2. Efficiency factors for space heating system in buildings
Open this publication in new window or tab >>Efficiency factors for space heating system in buildings
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis focuses on the efficiency of the space heating system. In particular, the efficiency factors measure the efficiency of thermal zone. The efficiency factors measures how the energy is used in a space heating. Efficiency factors relatively close to one mean that the energy is used "efficiently'', by contrast, efficiency factors close to the zero mean that the majority of the energy is lost to the outdoor environment. This method for the appraisal of space heating performance reads as if it is apparently simple and intuitive. In reality, the efficiency factor method has several pitfalls.

The thesis provides tools, insights and remarks on how to apply the efficiency factor method to space heating systems equipped with hydronic panel radiator and floor heating respectively. Models of the latter heaters together with the multilayer wall were developed and validated to understand the reliability of their predictions. The hypothesis is that the heat stored in the building thermal mass and heaters plays a role in defining the building thermal performance and as a result in the appraisal of the efficiency factors. The validation is based on the sensitivity bands of the models' predictions. The heaters were tested in in a thermostatic booth simulator. Benefits and drawbacks of each model were highlighted to increase awareness of their use in the engineering fields. The results showed how the models accounting for the heat stored performed the charging phase. In addition, results of how the multilayer wall delayed and damped down the heat wave coming from the outdoor environment were presented with the appraisal of the decrement factor and time delay of the indoor temperature. The results of the efficiency factors analysis reveal how the weather affects the efficiency of each locality situated in cold climates. Lastly how different control strategies impact on the efficiency factors of space heating and its distribution system. To conclude, this study highlights the paradoxes around the efficiency factor method. The thesis proposes how such factors have to be interpreted by researchers and scientists tackling the lack of information around this topic.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2018. p. 61
Keywords
Efficiency factors of space heating, hydronic panel radiator, hydronic floor heating, multilayer wall, numerical modelling, room control volume, decrement factor, time delay, heat conduction, heat convection, heat radiation, heat storage, thermal inertia, Euler solver, Newton-Raphson method, synthetic weather file, feedback and feed-forward control strategies, adaptive control, validation methodology, uncertainty bands, robustness of model predictions, thermostatic booth simulator, differential sensitivity analysis, transient model of panel radiator with multiple storage elements, active thermal mass, benchmark performance indicator, linear regression model, calibration through uncertainty bands, hybrid model of low-energy building: law driven + data driven, outdoor temperature compensation/heating curve, solar radiation model, finite difference method, heat equation
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-151981 (URN)978-91-7601-924-5 (ISBN)
Public defence
2018-10-22, N300, Naturvetarhuset, Umeå, Sweden, 13:00 (English)
Opponent
Supervisors
Available from: 2018-09-25 Created: 2018-09-21 Last updated: 2018-09-25Bibliographically approved

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Brembilla, ChristianÖstin, RonnyOlofsson, Thomas

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