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Development of Plate Heat Exchangers as Main Components of an Absorption Chiller

Hasenöhrl, Thomas (2011) In ISRN LUTMDN/TMHP--11/5234--SE
Department of Energy Sciences
Abstract (Swedish)
Absorption chillers are energy saving, but low-capacity applications are not available
yet. To become competitive with the established vapor-compression chillers, compact
and inexpensive main component heat exchangers are required. In the respective capacity
range, the conventionally used tube bundle heat exchangers can hardly fulfill that
requirement - plate heat exchangers, however, could. The present work evaluates cycle
and heat exchanger concepts for a four kilowatt lithium-bromide absorption chiller
based on compact plate heat exchangers. The preliminarily planned external temperatures
are 15/10C, 30/38C and 90/80C.
Cycle calculations show: Recirculation provides enough solution to permit good wetting
of the absorber. Two... (More)
Absorption chillers are energy saving, but low-capacity applications are not available
yet. To become competitive with the established vapor-compression chillers, compact
and inexpensive main component heat exchangers are required. In the respective capacity
range, the conventionally used tube bundle heat exchangers can hardly fulfill that
requirement - plate heat exchangers, however, could. The present work evaluates cycle
and heat exchanger concepts for a four kilowatt lithium-bromide absorption chiller
based on compact plate heat exchangers. The preliminarily planned external temperatures
are 15/10C, 30/38C and 90/80C.
Cycle calculations show: Recirculation provides enough solution to permit good wetting
of the absorber. Two concepts perform similarly. At the generator, recirculation requires
an additional pump. Alternatively, the generator could operate as a pool-generator, but
only if the external temperatures are adopted. Making evaporator/absorber and condenser/
generator pairwise equal in size results in a low overall heat exchanger area increase.
Consequently, two heat exchangers can be pressed on one plate, which lowers
the cost and allows to make the chiller more compact.
CFD-simulations of different plate heat exchangers show: Lowering the plate width,
which is favorable as to vapor pressure loss, hardly impacts the water side. Rotating
the channels towards the horizontal promises better wetting on the solution side,
but increases the pressure loss on the water side. Smaller channels between the water
channels supposedly increase wetting, too. Moreover, they increase the heat exchange
performance and reduce the pressure loss on the water side.
Integrating the wall of the pressure vessel and the solution distribution system into the
heat exchanger plates is an approach to further reduce the manufacturing costs and size
of the absorption chiller. (Less)
Please use this url to cite or link to this publication:
author
Hasenöhrl, Thomas
supervisor
organization
year
type
H1 - Master's Degree (One Year)
subject
keywords
chiller plate heat exchangers absorption
publication/series
ISRN LUTMDN/TMHP--11/5234--SE
report number
5234
ISSN
0282-1990
language
English
id
1978362
date added to LUP
2011-06-15 14:13:11
date last changed
2011-06-15 14:13:11
@misc{1978362,
  abstract     = {Absorption chillers are energy saving, but low-capacity applications are not available
yet. To become competitive with the established vapor-compression chillers, compact
and inexpensive main component heat exchangers are required. In the respective capacity
range, the conventionally used tube bundle heat exchangers can hardly fulfill that
requirement - plate heat exchangers, however, could. The present work evaluates cycle
and heat exchanger concepts for a four kilowatt lithium-bromide absorption chiller
based on compact plate heat exchangers. The preliminarily planned external temperatures
are 15/10C, 30/38C and 90/80C.
Cycle calculations show: Recirculation provides enough solution to permit good wetting
of the absorber. Two concepts perform similarly. At the generator, recirculation requires
an additional pump. Alternatively, the generator could operate as a pool-generator, but
only if the external temperatures are adopted. Making evaporator/absorber and condenser/
generator pairwise equal in size results in a low overall heat exchanger area increase.
Consequently, two heat exchangers can be pressed on one plate, which lowers
the cost and allows to make the chiller more compact.
CFD-simulations of different plate heat exchangers show: Lowering the plate width,
which is favorable as to vapor pressure loss, hardly impacts the water side. Rotating
the channels towards the horizontal promises better wetting on the solution side,
but increases the pressure loss on the water side. Smaller channels between the water
channels supposedly increase wetting, too. Moreover, they increase the heat exchange
performance and reduce the pressure loss on the water side.
Integrating the wall of the pressure vessel and the solution distribution system into the
heat exchanger plates is an approach to further reduce the manufacturing costs and size
of the absorption chiller.},
  author       = {Hasenöhrl, Thomas},
  issn         = {0282-1990},
  keyword      = {chiller
plate heat exchangers
absorption},
  language     = {eng},
  note         = {Student Paper},
  series       = {ISRN LUTMDN/TMHP--11/5234--SE},
  title        = {Development of Plate Heat Exchangers as Main Components of an Absorption Chiller},
  year         = {2011},
}