08-05-2012, 03:34 PM
Thermoeconomic Analysis of a Single and Double-Effect LiBr/H2O
Absorption Refrigeration System
[attachment=21577]
Introduction
Absorption refrigeration systems differ from
compression systems by the use of a heat source as the
energy input in order to operate; conversely, compressionbased
systems require mechanical energy to operate. Thus
the main advantage of the absorption systems is that they
can run burning a fuel or using waste heat recovered from
other thermal systems. Moreover, these systems present
other advantages, such as high reliability, low
maintainability and a silent and vibration-free operation
(New Buildings Institute, 1998). Another important aspect
is the elimination of CFC and HCFC refrigerants.
Single-effect absorption refrigeration systems have only
one heating level of the working fluid (dilute solution). The
coefficient of performance (COP) of these systems,
working with a LiBr/H2O solution, is in the range of 0.6 to
0.7 (Dorgan et al. 1995).
Functional Analysis for Absorption Refrigeration
Systems
Two cases were considered for the analysis of the
single-effect system. The first case considers a direct-fired
system whilst the second is a hot-water driven system as
part of a cogeneration system.
Two cases were also considered for the analysis of the
double-effect absorption refrigeration system. The first case
considers a direct-fired system while the second case is a
steam-driven system. The steam-driven system considers
that the absorption refrigeration system uses steam supplied
from a cogeneration system. The data used for these cases
were from Palacios-Bereche et al.
Functional Analysis for the Cogeneration System
In order to analyze the cases of the absorption
refrigeration systems driven by hot water and by steam, a
thermoeconomic functional analysis for the cogeneration
system should be done.
The cogeneration system considered in this study is
comprised of an internal combustion engine, a heat
recovery steam generator (HRSG), a mixer tank, and a
process.
Conclusions
In this work, new concepts are introduced to analyze an
absorption system. To perform the division in control
volumes, a thermal compressor was considered as a unique
volume and a functional exergoeconomic analysis with
negentropy was performed as well. These two new concept
applications permit a simpler and complete analysis to
provide easier comparisons with refrigeration systems
based on mechanical compression.
The exergetic costs and the unit exergetic costs for the
product of the system (single and double effect) is high due
to the low exergetic efficiency of the system (Palacios-
Bereche et al., 2007b).
Absorption Refrigeration System
[attachment=21577]
Introduction
Absorption refrigeration systems differ from
compression systems by the use of a heat source as the
energy input in order to operate; conversely, compressionbased
systems require mechanical energy to operate. Thus
the main advantage of the absorption systems is that they
can run burning a fuel or using waste heat recovered from
other thermal systems. Moreover, these systems present
other advantages, such as high reliability, low
maintainability and a silent and vibration-free operation
(New Buildings Institute, 1998). Another important aspect
is the elimination of CFC and HCFC refrigerants.
Single-effect absorption refrigeration systems have only
one heating level of the working fluid (dilute solution). The
coefficient of performance (COP) of these systems,
working with a LiBr/H2O solution, is in the range of 0.6 to
0.7 (Dorgan et al. 1995).
Functional Analysis for Absorption Refrigeration
Systems
Two cases were considered for the analysis of the
single-effect system. The first case considers a direct-fired
system whilst the second is a hot-water driven system as
part of a cogeneration system.
Two cases were also considered for the analysis of the
double-effect absorption refrigeration system. The first case
considers a direct-fired system while the second case is a
steam-driven system. The steam-driven system considers
that the absorption refrigeration system uses steam supplied
from a cogeneration system. The data used for these cases
were from Palacios-Bereche et al.
Functional Analysis for the Cogeneration System
In order to analyze the cases of the absorption
refrigeration systems driven by hot water and by steam, a
thermoeconomic functional analysis for the cogeneration
system should be done.
The cogeneration system considered in this study is
comprised of an internal combustion engine, a heat
recovery steam generator (HRSG), a mixer tank, and a
process.
Conclusions
In this work, new concepts are introduced to analyze an
absorption system. To perform the division in control
volumes, a thermal compressor was considered as a unique
volume and a functional exergoeconomic analysis with
negentropy was performed as well. These two new concept
applications permit a simpler and complete analysis to
provide easier comparisons with refrigeration systems
based on mechanical compression.
The exergetic costs and the unit exergetic costs for the
product of the system (single and double effect) is high due
to the low exergetic efficiency of the system (Palacios-
Bereche et al., 2007b).