Heat-transfer Enhancement for Slurries from Biogas Plants− Properties, processes, and thermal systems

↓ Direkt till sidans innehåll
↓ Direkt till sidans sekundära innehåll (sidomenyn)

Sökning: id:"swepub:oai:DiVA.org:ltu-89115" > Heat-transfer Enhan...

1 av 1
Föregående post
Nästa post
Till träfflistan

Heat-transfer Enhancement for Slurries from Biogas Plants− Properties, processes, and thermal systems

Chen, Jingjing (författare): Luleå tekniska universitet,Energivetenskap

Ji, Xiaoyan (preses): Luleå tekniska universitet,Energivetenskap

Lu, Bona, Professor (opponent): Institute of Process Engineering, University of Chinese Academy of Sciences, Beijing, China

(creator_code:org_t)

ISBN 9789180480260
Luleå : Luleå University of Technology, 2022
Engelska 67 s.
Serie: Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, 1402-1544

Relaterad länk:: https://ltu.diva-por... (primary) (Raw object); visa fler...; https://ltu.diva-por... (primary) (Raw object); https://urn.kb.se/re...; visa färre...

Doktorsavhandling (övrigt vetenskapligt/konstnärligt)

Abstract Ämnesord

Stäng

Biomethane production from renewable residues with anaerobic digestion gains increasing attention as a crucial alternative to petroleum fuels. It has been vigorously developed, but the large amounts of subsidy from the government indicate that the process efficiency needs to be further improved. For biomethane production, on the one hand, a great amount of heat needs to be used for heating the feeding slurry, sanitation of slurry, and maintaining the temperature in the large-scale reactors. On the other hand, a large amount of thermophilic effluent slurries brings a huge amount of waste heat, which can be recovered. This makes it important to study how to increase production by improving the thermal efficiency of biogas plants with novel heat exchangers. The working fluids in the biogas plants are the non-Newtonian and high-viscous slurries, and the conventional heat exchangers in biogas plants always show much lower performance compared to those in other industries. Normally, the slurries in the biogas plant consist of different substrates, including straw, manure, food waste, municipal sludge, and their mixtures, and various factors such as the amount and type of solids, particle size, shear rate, and temperature impact the rheological properties of the slurries, which makes the complexity in the rheological properties and the difficulty in developing novel heat exchangers.The development of heat exchangers calls for the rheological properties of slurries. However, to the best of our knowledge, only the rheology of manure slurry was systematically determined and modeled considering the effect of temperature. The lack of the rheological properties of slurries further hinders the design and development of novel geometries to enhance the heat transfer of the slurries. Correspondingly, the quantitative contribution and potential of the waste-heat recovery from the slurries to production using the enhanced geometry remain unclear. In this thesis work, to design novel geometry with heat-transfer enhancement for different slurries and determine its potential in thermal cycles in the full-scale biogas plants, firstly, the temperature-dependent rheological properties of the slurries, including the corn straw, food waste, and mixed slurries, were tested and modeled. It was found that these slurries possess strong shear-thinning behavior, the temperature has a significant impact on their dynamic viscosity, and the power-law model combined with the Arrhenius equation can describe the rheology well. Subsequently, with the reliable models of the rheological properties as the key input, Computational Fluid Dynamics simulations were conducted to screen different twisted geometries, determine the heat-transfer performance, and reveal the mechanism of the heat-transfer enhancement. Lab- and pilot-scale experiments were also conducted to validate the numerical results. The twisted hexagonal tubes show a positive enhancement factor up to 2.6 compared to normal heat exchangers in a wide range of operating conditions. The continuous and strong near-wall shear effect is the intrinsic reason for achieving a significant heat-transfer enhancement in the twisted hexagonal tubes. Moreover, the generalized engineering equations for predicting the effective shear rate and heat-transfer performance with measurable parameters were established and verified with both numerical and experimental results. Finally, the twisted-hexagonal-tube heat exchange was integrated with complete thermal cycles, including waste-heat recovery and external heating processes in the biogas plant, and the potential of increased production and profits were modeled and analyzed combined with the practical operating conditions in a full-scale biogas plant. It was found that for the waste-heat recovery using the twisted hexagonal tubes, the net raw biogas production can increase by up to 17.0 %, and for the external heating process, the increased profit equivalent to 39 % of total production can be achieved owing to energy conservation in external heating using the twisted-hexagonal-tube heat exchangers for a full-scale biogas plant.

Ämnesord

TEKNIK OCH TEKNOLOGIER -- Naturresursteknik -- Energisystem (hsv//swe)
ENGINEERING AND TECHNOLOGY -- Environmental Engineering -- Energy Systems (hsv//eng)
TEKNIK OCH TEKNOLOGIER -- Industriell bioteknik -- Bioteknisk apparatteknik (hsv//swe)
ENGINEERING AND TECHNOLOGY -- Industrial Biotechnology -- Bioengineering Equipment (hsv//eng)
TEKNIK OCH TEKNOLOGIER -- Maskinteknik -- Energiteknik (hsv//swe)
ENGINEERING AND TECHNOLOGY -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

heat-transfer enhancement
slurry
rheological properties
computational fluid dynamics
twisted tubes
biogas production
Energiteknik
Energy Engineering

Publikations- och innehållstyp

vet (ämneskategori)
dok (ämneskategori)

Hitta via bibliotek

Heat-transfer Enhancement for Slurries from Biogas Plants− Properties, processes... (Sök publikationen i LIBRIS)

Till lärosätets databas

1 av 1
Föregående post
Nästa post
Till träfflistan

Hitta mer i SwePub

Av författaren/redakt...: Chen, Jingjing; Ji, Xiaoyan; Lu, Bona, Profes ...

Om ämnet

TEKNIK OCH TEKNOLOGIER: TEKNIK OCH TEKNO ...; och Naturresurstekni ...; och Energisystem

TEKNIK OCH TEKNOLOGIER: TEKNIK OCH TEKNO ...; och Industriell biot ...; och Bioteknisk appar ...

TEKNIK OCH TEKNOLOGIER: TEKNIK OCH TEKNO ...; och Maskinteknik; och Energiteknik

Delar i serien: Doctoral thesis ...

Av lärosätet: Luleå tekniska universitet

Sök utanför SwePub

Sök vidare i:: Google; Google Book Search; Google Scholar

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

LIBRIS.kb.se