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
Identifying frost threshold in a balanced mechanical ventilation system by inlet and exhaust air temperature control
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.ORCID iD: 0000-0002-5938-4614
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology. Uponor AB.ORCID iD: 0000-0001-6266-8485
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology. Bravida Holding AB.ORCID iD: 0000-0001-5902-2886
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Frosting is a common issue in air-to-air heat recovery exchangers installed in buildings in cold climate countries. Further to the developed defrosting methods, frost prevention by preheating the outdoor air can reduce the energy usage in buildings. In this study, residential wastewater as a renewable heat source is used to preheat the outdoor air. Due to limited wastewater hourly flowrate and the impact of preheated air temperature on the efficiency of heat exchanger, controlling the preheating temperature is of utmost importance. In this investigation, preheated and exhaust air temperatures are monitored to generate an operational signal to the wastewater circulation pump. The cold surface at the heat exchanger and the dew point of the return air are analyzed to comprehend the condensation and frosting temperatures. The results show that in case of 30% relative humidity in the return air, the frosting threshold is at preheated and exhaust air temperatures below -2.2°C and 2.1°C, respectively. Using these temperatures as controlling parameters, the frosting period has decreased by 23%.

Place, publisher, year, edition, pages
2019.
Keywords [en]
Balanced mechanical ventilation; Frosting; Frosting threshold; Wastewater heat recovery; Energy saving
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-255622OAI: oai:DiVA.org:kth-255622DiVA, id: diva2:1340110
Conference
The 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC2019)
Note

QC 20190926

Available from: 2019-08-02 Created: 2019-08-02 Last updated: 2019-09-26Bibliographically approved
In thesis
1. Sustainable building ventilation solutions with heat recovery from waste heat
Open this publication in new window or tab >>Sustainable building ventilation solutions with heat recovery from waste heat
2019 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The energy used by building sector accounts for approximately 40% of the total energy usage. In residential buildings, 30-60% of this energy is used for space heating which is mainly wasted by transmission heat losses. A share of 20-30% is lost by the discarded residential wastewater and the rest is devoted to ventilation heat loss.

 

The main objective of this work was to evaluate the thermal potential of residential wastewater for improving the performance of mechanical ventilation with heat recovery (MVHR) systems during the coldest periods of year. The recovered heat from wastewater was used to preheat the incoming cold outdoor air to the MVHR in order to avoid frost formation on the heat exchanger surface.

 

Dynamic simulations using TRNSYS were used to evaluate the performance of the suggested air preheating systems as well as the impact of air preheating on the entire system. Temperature control systems were suggested based on the identified frost thresholds in order to optimally use the limited thermal capacity of wastewater and maintain high temperature efficiency of MVHR. Two configurations of air preheating systems with temperature stratified and unstratified tanks were designed and compared. A life cycle cost analysis further investigated the cost effectiveness of the studied systems.

 

The results obtained by this research work indicated that residential wastewater had the sufficient thermal potential to reduce the defrosting need of MVHR systems (equipped with a plate heat exchanger) in central Swedish cities to 25%. For colder regions in northern Sweden, the defrosting time was decreased by 50%. The temperature control systems could assure MVHR temperature efficiencies of more than 80% for most of the heating season while frosting period was minimized. LCC analysis revealed that wastewater air preheating systems equipped with temperature stratified and unstratified storage tanks could pay off their costs in 17 and 8 years, respectively.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019
Series
TRITA-ABE-DLT ; 1928
Keywords
wastewater heat recovery, balanced mechanical ventilation, defrosting reduction, heat recovery efficiency, thermal load shifting, renewables
National Category
Building Technologies
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-256567 (URN)978-91-7873-297-5 (ISBN)
Presentation
2019-09-20, M108, Stora konferensrummet, Brinellvägen 23, Stockholm, 09:00 (English)
Opponent
Supervisors
Funder
Svenska Byggbranschens Utvecklingsfond (SBUF), D6563
Note

QC 20190830

Available from: 2019-08-30 Created: 2019-08-28 Last updated: 2019-08-30Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

https://www.rehva.eu/fileadmin/events/2018/ISHVAC2019.pdf

Authority records BETA

Nourozi, BehrouzWang, QianPloskic, Adnan

Search in DiVA

By author/editor
Nourozi, BehrouzWang, QianPloskic, Adnan
By organisation
Fluid and Climate Technology
Building Technologies

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 42 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