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
Potential Energy Savings Made by Using a Specific Control Strategy when Tumble Drying Small Loads
Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
2013 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 102, 484-491 p.Article in journal (Refereed) Published
Abstract [en]

Tumble dryers manufactured today are optimised for their maximum capacity, i.e., 6–8 kg of dry load. An average washing load in ordinary households lands at between 2 and 3.5 kg dry load, which implies that the drying load is even smaller. The energy efficiency decreases with reduced drying load. The aim of this study is to establish a mathematical model for studying alternative control strategies for the venting tumble dryer in order to increase the energy efficiency of drying small loads. Two series of test runs were performed: the first series with three different drying loads was used as reference tests for validation of the mathematical model, and the second series was performed with airflow reduction. The model shows good agreement with the test runs. Two control strategies were tested using the model on the smallest drying load. By lowering the heat supply to the heater and by reducing the airflow, the energy efficiency increases by 6% in a small load drying cycle. It was not possible, however, for the investigated dryer, to reach the same energy efficiency for small loads as for the maximum drying load by using a control strategy.

Place, publisher, year, edition, pages
2013. Vol. 102, 484-491 p.
National Category
Energy Systems
Research subject
Environmental and Energy Systems
Identifiers
URN: urn:nbn:se:kau:diva-8245DOI: 10.1016/j.apenergy.2012.07.045ISI: 000314190800054OAI: oai:DiVA.org:kau-8245DiVA: diva2:440943
Available from: 2011-09-14 Created: 2011-09-14 Last updated: 2015-12-15Bibliographically approved
In thesis
1. Energy Efficiency Improvements of Tumble Dryers: -Technical Development, Laundry Habits and Energy Labelling
Open this publication in new window or tab >>Energy Efficiency Improvements of Tumble Dryers: -Technical Development, Laundry Habits and Energy Labelling
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Tumble dryers are becoming more and more common in ordinary households as a complement to the washing machine. Tumble dryers offer a fast drying cycle independent on weather conditions and require small space. They do, however, considering the large number of units use a large amount of electricity. The main objective in this thesis is to identify possibilities in order to reach a reduced electricity use for domestic tumble-drying of clothes. This involves an investigation of the condensing tumble dryer in order to point out possible energy efficiency improvements. The purpose of the energy label, which indicates the energy efficiency of the tumble dryer, is also studied, whether it matches the actual laundry habits. Finally, suggestions for technical development of the tumble dryer are made in line with today’s consumer behaviour.

The performance of the condensing tumble dryer has been studied using a design of experiments to create a statistical model in Paper I. This model was used to find the best settings for the power supply to the heater, the internal airflow and the external airflow in order to reach a high specific moisture extraction rate (SMER) and a low leakage ratio. A low external airflow and high power supply to the heater gives the highest SMER. To reach the lowest values for the leakage ratio, a low internal airflow should be applied together with a high external airflow. The use of a statistical model gave valuable information of the performance of the existing tumble dryer. For further improving the energy efficiency of the dryer, the amount of leakage and its location was investigated in Paper IV. By studying energy and mass balances from experiments, pressure measurements and modelling, the effects of leakage on the process were evaluated. As the location of the leakage is so important for the energy efficiency, the worst-case scenario where leakage is located between the heater and the drum is used as a start point in the study. It was determined that there is a large leakage of air between the heater and the drum leading to a significant loss in energy recovery.

The drying loads used by consumers are getting smaller, often less than 3 kg dry load, while the maximum capacity of the dryers are increasing, up to 7 or 8 kg. In Paper II, tests were made with different loads in order to investigate if the energy label serves its purpose as today’s standard is set at the dryers’ maximum capacity. The results from this study show that the energy efficiency when drying a small load is significantly lower than for a large load. In order to encourage a production of tumble dryers with higher energy efficiency for small loads, where the dryer is most frequently used, the standards for the energy label should be revised. Today, manufacturers do not gain any benefits by improving the performance for partial loads.

A mathematical model over a venting tumble dryer was established in Paper III with the aim of testing different control strategies in order to improve the energy efficiency of the tumble dryer for partial loads. The ideas behind the different strategies were to minimize the heat losses during the drying process and to increase the residence time for the air in the drum and thereby increase the moisture content of the air leaving the drum. Using such a control strategy it is possible to reach an improvement of SMER by approximately 4% when drying small loads. In order to reach larger improvements, however, a more extensive product development will be necessary.

Finally, the results in this thesis points at the necessity of including not only the technical development of the tumble dryer, but also the policy tools involved and the consumers’ habits in order to reach a reduced electricity use for drying clothes in households. 

Place, publisher, year, edition, pages
Karlstad: Karlstad University, 2011. 56 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2011:43
Keyword
drying, domestic, energy efficiency, textile, energy labelling standard
National Category
Energy Systems
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-8109 (URN)978-91-7063-378-2 (ISBN)
Public defence
2011-10-04, 11D 257 (Agardhsalen), Universitetsgatan 1, Karlstad, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2011-09-14 Created: 2011-08-23 Last updated: 2011-09-14Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Stawreberg, LenaNilsson, Lars
By organisation
Department of Energy, Environmental and Building Technology
In the same journal
Applied Energy
Energy Systems

Search outside of DiVA

GoogleGoogle Scholar

Altmetric score

Total: 496 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