Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Exergy analysis of single and multistep thermal processes
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
2011 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The present paper introduces the concepts of exergy and treats it applications to analysis of the gain in exergy efficiency between one step and multi-step thermal processes. The analysis, which is carried out with the Excel based SEPE program, is exemplified with the comparison between single step and two-steps heat pump setup for providing heat to a heat floor system and a domestic hot water. The paper discusses the use of the concept of exergy efficiency as a measure of success for design of a heat pump application and how the use of information on exergy destruction and temperature levels in different parts of the system add a new perspective to the analysis and the evaluation of the system performance. The paper shows how this information can be used to improve the system configuration and also the operation of the system for given boundary conditions. This is especially useful when the energy from the low temperature sources is can be utilized at different temperature or quality levels such as for space heating and domestic hot water.

Place, publisher, year, edition, pages
2011. 1-8 p.
Keyword [en]
thermal processes, exergy
National Category
Civil Engineering
Identifiers
URN: urn:nbn:se:kth:diva-53132OAI: oai:DiVA.org:kth-53132DiVA: diva2:468998
Conference
2nd International Exergy, Life Cycle Assessment, and Sustainability Workshop & Symposium (ELCAS2) 19 - 21 June, 2011, NISYROS - GREECE
Note
QC20120116Available from: 2012-01-16 Created: 2011-12-22 Last updated: 2012-11-21Bibliographically approved
In thesis
1. Exergy and Parametric Analysis: Methods and Concepts for a Sustainable Built Environment
Open this publication in new window or tab >>Exergy and Parametric Analysis: Methods and Concepts for a Sustainable Built Environment
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Energy use in the world is continuously increasing. In the last 30 years the use of primary energy worldwide has more than doubled and it is mainly supplied with fossil fuels. A more efficient use of energy in the built environment has to be pursued if a more sustainable development is to be attained.

The housing sector accounts for a major share of the energy use. Both in residential and commercial buildings, energy is mainly used for heating. Heat is energy with low quality. Traditional energy analysis methods, by failing to consider the energy quality, cannot give a holistic insight of the potential for reducing the energy used in the built environment. Exergy, instead, provides a tool to quantify the energy quality based on thermodynamic grounds.

In this thesis a methodology based on both the reduction of the energy demand and exergy demand in buildings is proposed to mitigate the problems related to the energy use in buildings through a reduced and more efficient use of energy.

The complex relations between building parameters to reduce the energy demand are managed with parametric analysis tools. The potential for energy demand reduction is investigated by means of screening analyses, local sensitivity analyses and global methods. A method for assessing the potential reduction of the energy demand in existing buildings and to evaluate the cost-efficiency of renovation measures based on the screening analysis is introduced and tested on two building typologies. In parallel, a program tool for parametric energy simulations, Consolis Parametric, has been developed on the core of an existing dynamic software, Consolis Energy +.

Factorial analysis has been used to investigate the relations between the reduction of the energy demand and of the energy supply when ground source heat pumps are used for heating and cooling. Optimal configurations- dependent on the insulation of the building- of number of boreholes and spacing were identified for minimum electricity consumption.

In the second part of this thesis exergy is used as tool for the definition of the efficient energy use in the built environment. The analysis of a multi-step heat pump to supply energy at two temperature levels, for space heating and domestic hot water production, exemplified how the reduction of the exergy loss can lead to a more efficient use of energy. The analysis was performed by means of SEPE, a modular software program developed in this work for exergy analysis in buildings.

For the systematic reduction of the exergy losses in the built environment, an important prerequisite is the reduction of the exergy required by the building. Systems like floor heating and cooling, based on low difference emission temperature, are examples of low-exergy systems. Buildings with reduced need of exergy input increase the efficiency of systems like heat pumps and enhance the use of low quality energy, like waste heat and energy from low temperature renewable sources.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. x, 69 p.
Series
Meddelande. Institutionen för byggvetenskap, ISSN 1651-5536 ; 209
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-105380 (URN)978-91-7501-539-2 (ISBN)
Public defence
2012-12-12, B2, Brinellvägen 23, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Formas
Note

QC 20121121

Available from: 2012-11-21 Created: 2012-11-20 Last updated: 2013-02-15Bibliographically approved

Open Access in DiVA

No full text

Other links

ELCAS 2

Search in DiVA

By author/editor
Jóhannesson, GudniMolinari, Marco
By organisation
Civil and Architectural Engineering
Civil Engineering

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 121 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf