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Investigating Different Opportunities to Increase Energy Efficiency in Buildings by Retrofitting Heat Pump Coupled Heat Recovery Systems
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration. (Uppvärmning och ventilationsteknik)ORCID iD: 0000-0003-3194-1762
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , vii, 117 p.
Series
TRITA-REFR, ISSN 1102-0245 ; 14:01
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
URN: urn:nbn:se:kth:diva-148784ISBN: 978-91-7595-214-7 (print)OAI: oai:DiVA.org:kth-148784DiVA: diva2:737060
Public defence
2014-09-05, Kollegiesalen, Brinellvägen 8, KTH, Sockholm, 09:00 (English)
Opponent
Supervisors
Note

QC 20140825

Available from: 2014-08-25 Created: 2014-08-11 Last updated: 2014-08-25Bibliographically approved
List of papers
1. Investigating the Efficiency of a Vertical Inline Drain Water Heat Recovery Heat Exchanger in a System Boosted with a Heat Pump
Open this publication in new window or tab >>Investigating the Efficiency of a Vertical Inline Drain Water Heat Recovery Heat Exchanger in a System Boosted with a Heat Pump
2014 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 80, 7-16 p.Article in journal (Refereed) Published
Abstract [en]

In the present study, the performance of a vertical inline drain water heat recovery heat exchanger is investigated. The system recovers the heat with the aid of a heat pump. To produce quality measurement data for the analysis special attention have been given to the calibration of sensors and the analysis of the propagation of uncertainty. The results from the analysis of the heat exchanger reveal that the contact resistance between the two copper pipes and the heat resistances on the inside of the drain water pipe are the dominating resistances to the heat transfer. Investigation of the heat recovery ratio shows that the heat exchanger has the capability to recover more than 25% of the available heat in the drain water at the flow rates investigated.

Keyword
Drain water heat recovery, Heat pump heat recovery, Coiled heat exchanger, Falling film heat transfer
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-148779 (URN)10.1016/j.enbuild.2014.05.003 (DOI)000343949400002 ()2-s2.0-84901983207 (Scopus ID)
Note

QC 20140825

Available from: 2014-08-11 Created: 2014-08-11 Last updated: 2017-12-05Bibliographically approved
2. Analyzing the efficiency of a heat pump assisted drain water heat recovery system that uses a vertical inline heat exchanger
Open this publication in new window or tab >>Analyzing the efficiency of a heat pump assisted drain water heat recovery system that uses a vertical inline heat exchanger
2014 (English)In: Sustainable Energy Technologies and Assessments, ISSN 2213-1388, E-ISSN 2213-1396, Vol. 8, 109-119 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of the present study is to accumulate knowledge on how a drain water heat recovery system using a vertical inline heat exchanger and a heat pump performs under different drain water flow profile scenarios. Investigating how the intermittent behavior of the drain water influences the performance for this type of system is important because it gives insight on how the system will perform in a real life situation. The scenarios investigated are two 24. h drain water flow rate schedules and one shorter schedule representing a three minute shower.The results from the present paper add to the knowledge on how this type of heat recovery system performs in a setting similar to a multi-family building and how sizing influences the performance. The investigation shows that a heat recovery system of this type has the possibility to recover a large portion of the available heat if it has been sized to match the drain water profile. Sizing of the heat pump is important for the system performance; sizing of the storage tank is also important but not as critical.

Keyword
Coiled heat exchanger, Drain water heat recovery, Falling film heat exchanger, Heat pump heat recovery
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-148780 (URN)10.1016/j.seta.2014.08.003 (DOI)2-s2.0-84907169290 (Scopus ID)
Note

QC 20150317. Updated from accepted to published.

Available from: 2014-08-11 Created: 2014-08-11 Last updated: 2017-12-05Bibliographically approved
3. Improving heat recovery using retrofitted heat pump in air handling unit with energy wheel
Open this publication in new window or tab >>Improving heat recovery using retrofitted heat pump in air handling unit with energy wheel
2014 (English)In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 62, no 2, 823-829 p.Article in journal (Refereed) Published
Abstract [en]

The world is facing a challenge to reduce energy use to meet the environmental goals set for the future. One factor that has a great impact on the energy performance of buildings is the ventilation losses. To handle these losses, heat recovery systems with rotating heat exchanger are often implemented. These systems have been shown to recover about 60-70% of the energy in the exhaust air on an annual basis. After a heat recovery system is installed it is hard to improve the efficiency of the installed recovery system with an acceptable economic payback period. In the present paper one way to improve the energy performance of a building with this type of heat recovery system by the use of a heat pump is investigated by simulations in TrnSys. The heat pump system is arranged so that the evaporator is connected to a heat exchanger mounted in the exhaust airstream after the energy wheel, and the condenser of the heat pump is mounted so that the temperature of return water from the heating coil is increased. The simulations show that there is a possibility to increase the heat recovery rate of the air handling unit in a significant way by retrofitting a heat pump to the system.

Keyword
Efficiency, Heat pump retrofit, Ventilation heat recovery, Air handling units, Energy performance, Energy performance of buildings, Heat pumps, Heat recovery systems, Payback periods, Recovery systems, Energy efficiency, Heat pump systems, Investments, Retrofitting, Waste heat, Waste heat utilization
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-139972 (URN)10.1016/j.applthermaleng.2013.09.059 (DOI)000330910700058 ()2-s2.0-84889835558 (Scopus ID)
Note

QC 20140121

Available from: 2014-01-21 Created: 2014-01-16 Last updated: 2017-12-06Bibliographically approved
4. Run-around coil ventilation heat recovery system: A comparative study between different system configurations
Open this publication in new window or tab >>Run-around coil ventilation heat recovery system: A comparative study between different system configurations
2012 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 90, no 1, 258-265 p.Article in journal (Refereed) Published
Abstract [en]

The energy performance of buildings in cold climates, with a considerable annual heating demand, is dependent on the ventilation air change rates (ACH). Buildings utilized for commercial use often have high annual ventilation heating demand due to high ACH required from indoor air quality aspect. In order for these buildings to have a reasonable energy performance a heat recovery system is often used to recover heat from the exhaust air to the makeup air. There are different variations of these systems; one that is sometimes used in Sweden is a run around coil heat recovery system. The present paper summarizes the findings from previous studies [5-7], and presents a comparative study, for three different cases; the traditional run-around coil heat recovery system; with a three stage on/off controlled heat pump retrofitted into the system; and with a variable capacity heat pump retrofitted into the system. Annual modeling (using TRNSYS) shows that by retrofitting a well-designed 3 stage heat pump to the system the annual heat recovery rate for the Stockholm case can be increased from 47% to 65%. For a retrofitted variable speed capacity heat pump for the Stockholm case the annual heat recovery improves from 47% to 66%. The modeling also shows that a well designed variable speed heat pump can cover 81% of the total ventilation heating demand and a well designed multi stage heat pump 77% of the total ventilation heating demand.

Keyword
Run-around coil, Ventilation heat recovery, Performance factors, Retrofitted heat pump
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-58808 (URN)10.1016/j.apenergy.2011.05.012 (DOI)000297426100039 ()2-s2.0-80055039757 (Scopus ID)
Note
QC 20120109Available from: 2012-01-09 Created: 2012-01-09 Last updated: 2017-12-08Bibliographically approved

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