U.S. patent application number 14/237051 was filed with the patent office on 2014-07-17 for heat pump system and method of cooling and/or heating by means of said system.
The applicant listed for this patent is Gianfranco Pelligrini. Invention is credited to Gianfranco Pelligrini.
Application Number | 20140196482 14/237051 |
Document ID | / |
Family ID | 44584502 |
Filed Date | 2014-07-17 |
United States Patent
Application |
20140196482 |
Kind Code |
A1 |
Pelligrini; Gianfranco |
July 17, 2014 |
HEAT PUMP SYSTEM AND METHOD OF COOLING AND/OR HEATING BY MEANS OF
SAID SYSTEM
Abstract
A heat pump system (100) comprising a first hydraulic circuit
(1) suitable to carry out a heat pump cycle in solution with a
first operating fluid which, during part of said cycle, is combined
with at least one auxiliary substance so as to form a material
system therewith, and a second hydraulic circuit (2) adapted to
carry out a compression heat pump cycle with a second operating
fluid. The first hydraulic circuit (1) comprises a first treatment
device (10) for the material system for separating from the
material system at least a fraction of the first operating fluid; a
first condenser (11) for at least partially condensing the first
operating fluid which has been separated; a first evaporator (13)
for at least partially evaporating the first operating fluid which
has been condensed, and a second treatment device (14) for the
material system for again incorporating in the material system the
first operating fluid which has been evaporated. The second
hydraulic circuit (2) comprises a second condenser (21) for at
least partially condensing the second operating fluid and an
evaporator (23) for evaporating the second operating fluid which
has been condensed. The second condenser thermally coupled with the
first treatment device (10) of the material system for transferring
heat released from the second operating fluid at the second
condenser (23) to the first treatment device (21) to separate said
at least a fraction of the first operating fluid from said material
system. A method of cooling and/or heating implementable by means
of said heat pump system (100) is also described.
Inventors: |
Pelligrini; Gianfranco;
(Torino, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pelligrini; Gianfranco |
Torino |
|
IT |
|
|
Family ID: |
44584502 |
Appl. No.: |
14/237051 |
Filed: |
August 2, 2012 |
PCT Filed: |
August 2, 2012 |
PCT NO: |
PCT/IB2012/053964 |
371 Date: |
February 4, 2014 |
Current U.S.
Class: |
62/79 ; 62/101;
62/115; 62/238.3; 62/238.7 |
Current CPC
Class: |
F25B 25/02 20130101;
Y02A 30/274 20180101; F25B 27/02 20130101; F25B 30/00 20130101;
F25B 7/00 20130101 |
Class at
Publication: |
62/79 ; 62/238.3;
62/238.7; 62/101; 62/115 |
International
Class: |
F25B 25/02 20060101
F25B025/02; F25B 27/02 20060101 F25B027/02; F25B 30/00 20060101
F25B030/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2011 |
IT |
TO2011A000732 |
Claims
1. Heat pump system comprising: a first hydraulic circuit suitable
to carry out a heat pump cycle with a first operating fluid which,
during part of said cycle, is combined with at least one auxiliary
substance so as to form a material system therewith, said first
hydraulic circuit comprising: a first treatment device for said
material system, in correspondence of which at least a fraction of
the first operating fluid is separated from said material system; a
first condenser, in correspondence of which the first operating
fluid which has been separated at least partially condenses, thus
releasing heat; a first evaporator, in correspondence of which the
first operating fluid which has been condensed at least partially
evaporates, thus absorbing heat, and a second treatment device for
said material system, in correspondence of which the first
operating fluid which has been evaporated is again incorporated in
said material system; a second hydraulic circuit suitable to carry
out a compression heat pump cycle with a second operating fluid,
said second circuit comprising: a second condenser, in
correspondence of which said second operating fluid at least
partially condenses, thus releasing heat, and a second evaporator
in correspondence of which said second operating fluid evaporates,
thus absorbing heat, characterized in that said second condenser is
thermally coupled with said first treatment device to transfer heat
released from said second operating fluid in correspondence of said
second condenser to said first treatment device for separating said
at least one fraction of the first operating fluid from said
material system.
2. Heat pump system according to claim 1, wherein said second
treatment device is thermally coupled with said second evaporator
to transfer heat released in correspondence of said second
treatment device to said second operating fluid in correspondence
of said second evaporator.
3. Heat pump system according to claim 1, wherein said first
condenser is thermally coupled with said second evaporator to
transfer heat released from said first operating fluid in
correspondence of said first condenser to said second operating
fluid in correspondence of said second evaporator.
4. Heat pump system according to claim 1 previous claims,
comprising a third hydraulic circuit suitable to carry out a
compression heat pump cycle with a third operating fluid, wherein
said third hydraulic circuit comprises a third condenser, in
correspondence of which said third operating fluid releases heat
while at least partially condensing, and wherein said third
condenser is thermally coupled with said second evaporator to
transfer heat released from said third operating fluid in
correspondence of said third condenser to said second operating
fluid in correspondence of said second evaporator.
5. Method of cooling and/or heating by means of a heat pump system,
comprising the steps of: a) carrying out a heat pump cycle with a
first operating fluid which, during part of said cycle, is combined
with at least one auxiliary substance so as to form a material
system therewith, said cycle comprising the steps of: a1)
separating at least a fraction of said first operating fluid from
said material system; a2) at least partially condensing the first
operating fluid which has been separated; a3) at least partially
evaporating the first operating fluid which has been condensed, and
a4) incorporating the first operating fluid which has been
evaporated again in said material system; b) carrying out a
compression heat pump cycle by means of a second operating fluid,
said cycle comprising the steps of: b1) at least partially
condensing said second operating fluid, and b2) at least partially
evaporating said second operating fluid which has been condensed,
characterized by the step of c) transferring heat released from
said second operating fluid during said condensation step b1) to
said material system for separating said at least a fraction of
said first operating fluid therefrom during said separation step
a1).
6. Method according to claim 5, wherein in said step b1) said
second operating fluid has a temperature between about 70.degree.
C. and about 95.degree. C.
7. Method according to claim 5, comprising the step of: d)
transferring heat released upon the incorporation of said first
operating fluid in said material system during said incorporation
step a4) to said second operating fluid in said evaporation step
b2).
8. Method according to claim 6, comprising the step of: d)
transferring heat released upon the incorporation of said first
operating fluid in said material system during said incorporation
step a4) to said second operating fluid in said evaporation step
b2).
9. Method according to claim 5, comprising the step of: e)
transferring heat released from said first operating fluid during
said condensation step a2) to said second operating fluid in said
evaporation step b2).
10. Method according to claim 6, comprising the step of: e)
transferring heat released from said first operating fluid during
said condensation step a2) to said second operating fluid in said
evaporation step b2).
11. Method according to claim 8, wherein in said step a2), said
first operating fluid has an average temperature between about
40.degree. C. and about 70.degree. C.
12. Method according to claim 9, comprising the steps of: f)
carrying out a further compression heat pump cycle by means of a
third operating fluid, said cycle comprising the step of: f1) at
least partially condensing said third operating fluid; g)
transferring heat released from said third operating fluid during
said condensation step f1) to said second operating fluid in said
evaporation step b2).
13. Method according to claim 10, comprising the steps of: f)
carrying out a further compression heat pump cycle by means of a
third operating fluid, said cycle comprising the step of: f1) at
least partially condensing said third operating fluid; g)
transferring heat released from said third operating fluid during
said condensation step f1) to said second operating fluid in said
evaporation step b2).
14. Method according to claim 12, wherein in said step g) said
third operating fluid has an average temperature between about
30.degree. C. and about 60.degree. C.
15. Method according to claim 13, wherein in said step g) said
third operating fluid has an average temperature between about
30.degree. C. and about 60.degree. C.
16. Method according to any one of claim 5, wherein said heat pump
cycle carried out with said first operating fluid is an absorption
heat pump cycle.
17. Method according to any one of claim 5, wherein said heat pump
cycle carried out with said first operating fluid is an adsorption
heat pump cycle.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a heat pump system and to a
method of cooling and/or heating by means of said system.
PRIOR ART
[0002] The heat pumps for cooling and/or heating environments
and/or liquids that are nowadays in widespread use in principle
fall into one of two categories: compression heat pumps and
absorption heat pumps.
[0003] In compression heat pumps, an operating fluid in the vapour
state is compressed to raise it to a higher cycle pressure. Then
the compressed operating fluid condenses at least partially, giving
off heat, at a condenser where a heat exchange takes place with an
environment or a fluid at a higher cycle temperature.
[0004] Subsequently, the condensed operating fluid is expanded to
bring it to a lower cycle pressure. Finally, the expanded operating
fluid evaporates, by absorbing heat, at an evaporator where a heat
exchange takes place with an environment or a fluid at a lower
cycle temperature, and thus returns to the aspiration conditions of
the compressor.
[0005] In absorption heat pumps, instead, two fluids operate. The
latter are capable of forming a homogenous solution in the liquid
phase: a fluid at a higher vapour pressure, which operates as the
operating fluid and normally represents the solute, and an
auxiliary fluid at a lower vapour pressure, which normally
represents the solvent. The most common operating fluid-auxiliary
fluid pairs consist respectively of water and lithium bromide
(H.sub.2O--LiBr) or ammonia and water (NH.sub.3--H.sub.2O).
[0006] In an absorption heat pump, the operating fluid completes a
part of the heat pump cycle, in particular the compression phase,
in liquid solution with the auxiliary fluid.
[0007] In particular, in an absorption heat pump the liquid
solution containing the operating fluid is pumped at a higher
pressure of the cycle, and is therefore sent to a device--generally
referred to by the term "generator"--in which at least one fraction
of the operating fluid is separated from the solution by supplying
heat.
[0008] Thereafter, analogously to what happens in a compression
cycle, the separated operating fluid, in the vapour state, at least
partially condenses, giving off heat, at a condenser where a heat
exchange takes place with an environment or a fluid at a higher
cycle temperature. Then the condensed operating fluid is expanded
to bring it to a lower cycle pressure. Subsequently the expanded
operating fluid at least partially evaporates, by absorbing heat,
at an evaporator where a heat exchange takes place with an
environment or a fluid at a lower cycle temperature.
[0009] Finally the evaporated operating fluid is sent to a
device--generally referred to by the term "absorber"--in which said
operating fluid again goes into solution with the impoverished
solution containing the auxiliary fluid, coming from the
generator.
[0010] Whereas in compression heat pumps the energy entering the
cycle, which energy is necessary for compression of the operating
fluid in the vapour state, is supplied in the form of
electrical/mechanical energy, in absorption heat pumps most of the
energy entering the cycle--that is to say, the energy supplied at
the generator for separating the operating fluid from the solution,
being comparatively negligible the energy required for pumping the
liquid solution to the higher pressure--is supplied in the form of
thermal energy. This thermal energy is made available either
purposively, in general by burning a fuel in a boiler, or by
recovering waste heat deriving from a prime mover or from other
processes in which it is available at a suitable temperature.
[0011] In addition to the very low electrical energy requirement of
absorption heat pumps, which is in all cases negligible by
comparison with compression heat pumps since they have few moving
parts, the absorption heat pumps also have advantages over
compression heat pumps that are linked to good performance at
partial loads, good reliability and long useful life, low noise and
the substantial absence of vibrations.
[0012] However, absorption heat pumps have coefficients of
performance (COPs) that are appreciably lower than those now
typical of compression heat pumps of equal potentiality. For
example, with single-stage absorption heat pumps operating with
H.sub.2O--LiBr, values of COP--understood as the ratio between the
thermal energy supplied and the refrigeration or thermal energy
produced--between 0.6 and 1.4 can be achieved, depending on the
temperature at which the thermal energy is supplied to the
generator.
[0013] Compression heat pumps and absorption heat pumps can be used
in cooling and/or heating installations both singly and in
combination.
[0014] A combined use of a compression heat pump and an absorption
heat pump is known for example from JP 2004101035 A and U.S. Pat.
No. 4,471,630.
[0015] These documents disclose cooling systems comprising a
compression heat pump unit and an absorption heat pump unit having
a heat exchange relationship with a consumer circuit. For the
purpose of improving the heat exchange with the consumer circuit
and/or of improving the working at partial loads, various methods
of connecting the two heat pump units to the consumer circuit are
proposed that are substantially ascribable to connection of these
units in series or in parallel with respect to the consumer
circuit. In all cases, the two heat pump units are present as
distinct units, hydraulically and thermally independent of one
another.
[0016] Due to the combined use of compression heat pumps and
absorption heat pumps, systems of the above-mentioned type enable
improvements in flexibility of use where there are heat consumers
of differing type, as well as in performances at partial loads.
However, these systems have relatively low overall efficiency, in
particular when the thermal energy to be supplied to the absorption
heat pump is not available as waste heat and must therefore be made
available purposively.
[0017] Consequently, taking into account the higher costs and
greater complexity from the installation point of view, these
systems may in practice be uncompetitive as compared with solutions
using a single type of heat pump.
[0018] Furthermore, the presence of two physically distinct heat
pump units together causes problems of bulkiness in the
above-mentioned systems which limit the possibility of their
use.
SUMMARY OF THE INVENTION
[0019] The technical problem underlying the present invention
consists in providing a heat pump system which allows a synergistic
exploitation of the advantageous characteristics typical of
absorption heat pumps--or, more generally, heat pumps in which the
operating fluid during one part of the thermodynamic cycle is
combined with at least one auxiliary substance so as to form a
material system--therewith, which heat pumps are referred to in
what follows, for the sake of brevity, as "combined heat
pumps"--and of compression heat pumps. In particular, it is needed
a heat pump system which is capable of satisfying, also
simultaneously, a plurality of heat consumers having different
requirements in terms of the demand for refrigerating/thermal power
and of operating temperatures, and/or of operating under conditions
of partial load by sustaining, at the same time, high values of
COP.
[0020] A further problem dealt with by the present invention
consists in providing a heat pump system having the above-mentioned
characteristics which is also as compact as possible.
[0021] Within the scope of the present description and of the
claims which follow, the expression "material system" is used to
refer to a group of substances which, within specified intervals of
temperature and pressure, show a substantially uniform behaviour,
in particular with respect of their transportation within the heat
pump circuit. The material system, just like the at least one
auxiliary substance which together with the operating fluid form
part thereof, may be present in the form of a fluid or solid. In
particular, the material system may be a solution or a liquid
mixture of the operating fluid with said at least one auxiliary
substance--as in the absorption heat pumps--or a system formed by
the absorption of the operating fluid in a solid matrix, as in the
heat pumps or absorption refrigerators.
[0022] The Applicant has noted that the above-mentioned problems
can be resolved by means of a system adapted to simultaneously
carry out a combined heat pump cycle and a compression heat pump
cycle, thermally coupled with one another.
[0023] In particular, in a first aspect, the invention relates to a
heat pump system comprising: [0024] a first hydraulic circuit
suitable to carry out a heat pump cycle with a first operating
fluid which, during a part of said cycle, is combined with at least
one auxiliary substance so as to form a material system therewith,
said first hydraulic circuit comprising: [0025] a first treatment
device for said material system, in correspondence of which at
least a fraction of the first operating fluid is separated from
said material system; [0026] a first condenser, in correspondence
of which the first operating fluid which has been separated at
least partially condenses by releasing heat; [0027] a first
evaporator, in correspondence of which the first operating fluid
which has been condensed at least partially evaporates, by
absorbing heat, and [0028] a second treatment device for said
material system, in correspondence of which the first operating
fluid which has been evaporated is again incorporated in said
material system; [0029] a second hydraulic circuit suitable to
carry out a compression heat pump cycle with a second operating
fluid, said second circuit comprising: [0030] a second condenser,
in correspondence of which said second operating fluid at least
partially condenses, by releasing heat, and [0031] a second
evaporator, in correspondence of which said second operating fluid
evaporates, by absorbing heat, characterized in that said second
condenser is thermally coupled with said first treatment device so
as to transfer the heat released from said second operating fluid
in correspondence of said second condenser to said first treatment
device for separating said at least one fraction of the first
operating fluid from said material system.
[0032] The heat pump system of the invention is, in all respects, a
"hybrid" heat pump in which the heat released by the second
operating fluid in the compression heat pump cycle may be used,
wholly or in part, in the combined heat pump cycle to achieve the
separation of the first operating fluid from the material system
formed with the auxiliary substance.
[0033] With regard to the energy balance of the heat pump of the
invention with respect to the external environment, it is noted
that, in the face of an energy expenditure essentially for the
compression of the second operating fluid, the principal useful
effect achieved is the production of refrigerating power in
correspondence of the evaporator and/or of thermal power in
correspondence of the condenser of the first hydraulic circuit for
carrying out the combined heat pump cycle. Furthermore, depending
on the specific configurations and the operating modalities of the
system, a further useful effect may be the production of
refrigerating power in correspondence of the evaporator of the
second hydraulic circuit for carrying out the compression heat pump
cycle and/or the production of thermal power in correspondence of
the second treatment device of the material system of the first
hydraulic circuit for carrying out the combined heat pump
cycle.
[0034] Advantageously, due to the multiplicity of above-mentioned
useful effects, the heat pump system of the invention is capable of
simultaneously handling a plurality of heat consumers with
differing requirements in terms of demand for refrigerating/thermal
power and/or of operating temperatures, such as for example
installations for cooling/conditioning and/or heating environments,
installations for the production of domestic hot water, or for
heating of volumes of water for other uses, such as water for
swimming pools, installations for the cooling/heating of process
fluids, etc. This aspect is especially advantageous in the case of
use in large buildings or building complexes, both for private
habitation, for example large blocks of flats, skyscrapers, etc,
and public buildings, for example hospitals, schools, business
parks or sports centres, etc.
[0035] Moreover, the production of a combined heat pump cycle and a
compression heat pump cycle thermally coupled together enables to
obtain thermodynamic operating conditions for the single components
of the installation that are in general more advantageous than
those obtainable--external conditions being regarded as equal--for
the same components operating in non-coupled heat pump cycles. This
advantageously translates into the possibility of obtaining
appreciably higher COPs than those typical of systems of the known
art, comprising absorption and compression heat pumps as distinct
and thermally uncoupled units.
[0036] In particular, numerical simulations conducted by the
Applicant with reference to applications of practical interest have
shown that the heat pump system of the invention is able to achieve
COP values within the range of 3 to 15, depending on the operating
conditions and refrigerating and/or thermal powers actually used as
the useful effect.
[0037] Advantageously, moreover, the thermal coupling between the
two heat pump cycles also permits operating conditions to be
managed effectively at partial loads, without appreciable
repercussions on the COP.
[0038] Finally, again due to the thermal coupling between the two
heat pump cycles, it is possible to integrate the components at
which heat exchanges take place between the two hydraulic circuits.
The heat pump system of the invention can therefore be
advantageously produced in more compact forms as compared with
known systems comprising absorption and compression heat pumps as
distinct units.
[0039] In a second aspect, the invention relates to a method of
cooling and/or heating comprising the steps of: [0040] a) carrying
out a heat pump cycle with a first operating fluid which, during
part of said cycle, is associated with an auxiliary substance so as
to form a material system therewith, said cycle comprising the
steps of: [0041] a1) separating at least a fraction of said first
operating fluid from said material system; [0042] a2) at least
partially condensing the first operating fluid which has been
separated; [0043] a3) at least partially evaporating the first
operating fluid which has been condensed, and [0044] a4)
incorporating the first operating fluid which has been evaporated
again in said material system; [0045] b) carrying out, by means of
a second operating fluid, a compression heat pump cycle comprising
the steps of: [0046] b1) at least partially condensing said second
operating fluid, and [0047] b2) at least partially evaporating said
second operating fluid which has been condensed, characterised by
the step of [0048] c) transferring heat released from said second
operating fluid during said condensation step b1) to said material
system for separating said at least one fraction of said first
operating fluid therefrom during said separation step a1).
[0049] Due to the transfer of heat between the first and second
operating fluid in step c), and therefore to the thermal coupling
between the combined heat pump cycle and the compression heat pump
cycle, which is carried out in this method, it is advantageously
possible to handle a plurality of heat consumers having differing
requirements in terms of the demand for refrigerating/thermal power
and of operating temperatures, in all cases maintaining elevated
values of COP, in a way analogous to that already described with
reference to the heat pump system of the invention.
[0050] Preferred embodiments of the two aspects of the invention
described above are the subject of the respective dependent claims,
the content of which is included here in its entirety for
reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] Further features and advantages of the present invention
will be clearer from the following description of some of its
preferred embodiments, which is given here in what follows by way
of non-limiting illustration with reference to the attached
figures, wherein:
[0052] FIGS. 1a, 1b show schematic circuit diagrams of two variants
of a first preferred embodiment of the heat pump system of the
invention;
[0053] FIGS. 2a, 2b show schematic circuit diagrams of two variants
of a second preferred embodiment of the heat pump system of the
invention;
[0054] FIGS. 3a, 3b show schematic circuit diagrams of two variants
of a third preferred embodiment of the heat pump system of the
invention;
[0055] FIGS. 4a, 4b show schematic circuit diagrams of two variants
of a fourth preferred embodiment of the heat pump system of the
invention;
[0056] FIG. 5 is a block diagram showing a first embodiment of the
cooling and/or heating method of the invention, which may be
carried out by means of the heat pump system of FIGS. 1a, 1b or
FIGS. 4a, 4b;
[0057] FIG. 6 is a block diagram showing a second embodiment of the
cooling and/or heating method of the invention, which may be
carried out by means of the heat pump system of FIGS. 2a, 2b,
and
[0058] FIG. 7 is a block diagram showing a first embodiment of the
cooling and/or heating method of the invention, which may be
carried out by means of the heat pump system of FIGS. 3a, 3b or
FIGS. 4a, 4b.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0059] In FIGS. 1-4, a heat pump system according to the present
invention is indicated overall by the reference numeral 100.
[0060] The heat pump system 100 comprises a first hydraulic circuit
1, indicated by a thick solid line, suitable to carry out a
combined heat pump cycle with a first operating fluid which, during
part of the cycle, forms a material system with a suitable
auxiliary substance, and a second hydraulic circuit 2, indicated
with a thick dot-dashed line, suitable to carry out a compression
heat pump cycle with a second operating fluid.
[0061] With regard to the first hydraulic circuit 1, for the sake
of clarity, in the following description reference will be made to
preferred embodiments of the invention, in which the combined heat
pump cycle carried out in this hydraulic circuit is in particular
an absorption heat pump cycle, in which the material system--that
the first operating fluid forms with the auxiliary substance during
part of the cycle--is a liquid solution.
[0062] In other preferred embodiments of the invention, not
described in detail here, the combined heat pump cycle may be an
absorption heat pump cycle, in which the material system--that the
first operating fluid forms with the auxiliary substance during
part of the cycle--is a solid mass, for example in the form of
granules or panels, on to which the operating fluid is
adsorbed.
[0063] In particular, therefore, the first hydraulic circuit 1
comprises a so-called "generator" 10 as the first device for
treating the liquid solution (material system) formed with the
auxiliary substance, a condenser 11, an expansion device 12 for
expanding the operating fluid, e.g. a laminating valve, an
evaporator 13 and a so-called "absorber" 14 as a second device for
treating the liquid solution (material system) formed with the
auxiliary substance.
[0064] In the generator 10, at least a fraction, and possibly the
most part of the first operating fluid is separated, by means of
heating, from the liquid solution formed with the auxiliary
substance. Therefore there exit from the generator 10, the first
operating fluid substantially pure, in the vapour state under
higher temperature and pressure conditions of the cycle, and a
solution poor in operating fluid ("poor solution"), in the liquid
state, which solution contains substantially all the auxiliary
solution. The separated first operating fluid then arrives at the
condenser 11, where it releases heat by condensing at least in part
by means of an heat exchange with an environment or a fluid at a
higher cycle temperature. Following the expansion in the expansion
device 12, the first operating fluid then arrives at the evaporator
13, where it absorbs heat by evaporating at least in part by means
of an heat exchange with an environment or a fluid at a lower cycle
temperature.
[0065] The evaporated first operating fluid is then sent to the
absorber 14, in which said operating fluid again goes into solution
with the poor solution, usually by an exothermic process. The poor
solution discharged from the generator 10 is returned to the
absorber 14 by means of a suitable recirculation line 15. The
solution thus obtained, which is rich in operating fluid, is then
again sent to the generator 10 by means of a pump 16.
[0066] A regenerative heat exchanger 17 is preferably arranged
between the recirculation line 15 and a delivery branch 18 of the
pump 16, so as to pre-heat the rich solution as it enters the
generator 10 by recovering heat from the poor solution discharged
from the generator 10 itself.
[0067] The second hydraulic circuit 2 for carrying out the
compression heat pump cycle comprises a condenser 21, in
correspondence of which the second operating fluid releases heat by
condensing at least partially by means of an heat exchange with an
environment or a fluid at a higher cycle temperature, an expansion
device 22, for example a laminating valve, for expanding the second
condensed operating fluid, an evaporator 23 in correspondence of
which the second fluid absorbs heat and evaporates by means of heat
exchange with an environment or a fluid at a lower cycle
temperature, and a compressor 25 for compressing the evaporated
second operating fluid and returning it to the condenser 21 under
entry conditions of pressure and temperature.
[0068] According to the invention, the condenser 21 of the second
hydraulic circuit 2 is thermally coupled with the generator 10 of
the first hydraulic circuit 1, so that the heat released by the
second operating fluid in correspondence of the condenser 21 can be
transferred to the generator 10, where it is used for the process
of separating the first operating fluid from the solution in the
absorption heat pump cycle. In other words, the condenser 21 of the
second fluid is advantageously utilised as a source of heat for the
generator 10 of the material circuit. As regards the energy
balance, the sole energy expenditure is represented by the
electrical energy necessary for functioning of the compressor 25 of
the second hydraulic circuit 2. Differently from the known
solutions, in the heat pump system according to the invention no
"external source" is required to supply thermal energy to the
generator 10 of the first hydraulic circuit. On the contrary,
according to the invention, the condenser 21 of the second circuit
2 represents, for the generator 10 of the first hydraulic circuit
1, a source of thermal power "internal" to the system with great
advantages, from an energetic point of view, as will become
apparent from the following description.
[0069] The thermal coupling between the generator 10 and the
condenser 21 can be achieved in practice by producing these
components according to an integrated design, as shown
schematically in FIGS. 1a, 2a, 3a, and 4a, with full advantages in
reduction of bulkiness. Alternatively, the generator 10 and the
condenser 21 may be kept separate and be positioned in an heat
exchange relationship by means of an intermediate hydraulic circuit
4 fitted with a circulating pump 40 for circulating a suitable
heat-conductive fluid, as shown schematically in FIGS. 1b, 2b, 3b,
and 4b, in which the intermediate hydraulic circuit 4 is indicated
with a thin continuous line.
[0070] In a first preferred embodiment of the heat pump system 100,
shown in FIGS. 1a and 1b, there is a further thermal coupling
between the absorption heat pump cycle and the compression heat
pump cycle, created between the absorber 14 of the first hydraulic
circuit 1 on and the evaporator 23 of the second hydraulic circuit
2 in such a way that the heat released in correspondence of the
absorber 14 can be transferred to the second operating fluid in
correspondence of the evaporator 23, to carry out at least
partially the evaporation of said second operating fluid within the
compression heat pump cycle.
[0071] Since the passing into solution of the first operating fluid
with the auxiliary substance in an absorption heat pump cycle or,
more generally, the incorporation of said fluid in the material
system formed with the auxiliary substance in a combined heat pump
cycle, is normally an exothermic process, with this embodiment it
is advantageously possible to use the heat released from the
absorber 14 to enable the evaporator 23 to operate at temperatures
higher than those typical in compression heat pump cycles, in which
pump the evaporator is in an heat exchange relationship with the
external environment. This enables the energy required for
compression of the second operating fluid to be appreciably
reduced--for equal amounts of heat released in correspondence of
the condenser 21--and therefore advantageously to achieve a further
increase in the COP of the heat pump system 100.
[0072] Moreover, due to the high temperature (typically around
70.degree. C.) which in this embodiment the first operating fluid
can reach at the condenser 11 of the first hydraulic circuit 1, in
the case of cooling operation it is advantageously possible to
consume the heat released by the first operating fluid at such a
component by using only air heat exchangers, even in the presence
of very high temperatures (even higher than 60.degree. C.) of the
external environment. It is therefore possible to avoid the use of
cooling towers and the related disadvantages of bulkiness, the
consumption of water and electrical energy, and the undesirable
presence of large volumes of water at a temperature capable of
developing bacteria or other harmful microorganisms. This last
aspect represents a problem in particular in the case of use in
hospitals or other medical installations.
[0073] This embodiment of the heat pump system 100 may therefore
have an advantageous application in particular for the generation
of cold at high efficiency in regions with a generally very hot
and/or dry climate, in particular in applications in which the use
of cooling towers is not possible (for example, in skyscrapers), or
is not recommended (for example in medical installations or
hospitals).
[0074] The refrigerating power obtained with the aid of the
evaporator 13 may be used in general to cool a service fluid
circulating within a cooling circuit indicated schematically in
FIGS. 1a and 1b by the fine dashed line. However, analogously
thereto, the thermal power obtained with the aid of the condenser
11 may be used in general to heat a service fluid circulating
within a heating circuit also indicated schematically in FIGS. 1a
and 1b by the dash-dot-dotted line. The expression heating/cooling
circuit is intended to indicate generically any "users" adapted to
utilise the refrigerating/thermal power generated by means of the
system according to the invention.
[0075] Thermal coupling between the absorber 14 and the evaporator
23 can be achieved in practice by producing these components with
an integrated design, as shown schematically in FIG. 1a.
Alternatively, these components may be kept separate and arranged
in an heat exchange relationship by means of an intermediate
hydraulic circuit 5 fitted with a circulating pump 50 for
circulating a suitable heat-conductive fluid, as shown
schematically in FIG. 1b, where the intermediate hydraulic circuit
5 is indicated with a thin continuous line.
[0076] In a second preferred embodiment of the heat pump system
100, shown in FIGS. 2a and 2b, the condenser 11 of the first
hydraulic circuit 1 is thermally coupled with the evaporator 23 of
the second hydraulic circuit in such a way that the heat released
by the first operating fluid in correspondence of the condenser 11
can be transferred to the second operating fluid in correspondence
of the evaporator 23 to achieve at least partially the evaporation
of the second operating fluid in the compression heat pump
cycle.
[0077] This embodiment further increases the advantages obtained
with the embodiment previously described in respect of the increase
in COP deriving from a reduction in the energy required for
compression of the second operating fluid. In other words, the
thermal energy deriving from condensation of the first fluid of the
first hydraulic circuit 1 is advantageously used to raise the
thermal level of the second fluid of the second circuit 2 at the
outlet of the evaporator 23 so as to greatly limit the work
required for the compressor. This obviously translates into a
reduction in the electrical energy used, i.e. an increase in the
COP.
[0078] In summary, the further advantageous aspect of this
embodiment therefore relates to the possibility of producing both
refrigerating power (at the evaporator 13) and thermal power at an
intermediate temperature (at the absorber 14) while maintaining
elevated COPs. The thermal power at intermediate temperature can
for example be used to produce domestic hot water, for
dehumidification, etc.
[0079] In FIGS. 2a and 2b, the dashed line indicates schematically
a cooling circuit wherein there circulates an operating fluid
adapted to be cooled by the refrigerating power generated by the
evaporator 13 of the first hydraulic circuit 1.
[0080] In the same figures, the dash-dot-dot line indicates
schematically a heating circuit in which an service fluid, suitable
to be heated by the thermal power generated by the absorber 14 of
the first hydraulic circuit 1, circulates.
[0081] The thermal coupling between the condenser 11 and the
evaporator 23 can be achieved in practice by producing these
components with an integrated design, as shown schematically in
FIG. 2a. Alternatively, these components may be kept separate and
be arranged in a heat exchange relationship by means of an
intermediate hydraulic circuit 6 fitted with a circulating pump 60
for circulating a suitable heat-conductive fluid, as shown
schematically in FIG. 2b, in which the intermediate hydraulic
circuit 6 is indicated with a thin continuous line.
[0082] In a third preferred embodiment of the heat pump system 100,
shown in FIGS. 3a and 3b, the latter hydraulic circuit comprises a
third hydraulic circuit 3 suitable to carry out a compression heat
pump cycle with a third operating fluid, indicated in the drawings
with a thick broken line.
[0083] The third hydraulic circuit 3, analogously to the second
hydraulic circuit 2, comprises the condenser 31, in correspondence
of which the third operating fluid releases heat, by condensing at
least partially, an expansion device 32, for example a laminating
valve, for expanding the condensed second operating fluid, an
evaporator 33 n correspondence of which the second fluid absorbs
heat and evaporates, and a compressor 35 for compressing the
evaporated second operating fluid and returning it to the condenser
31 under entry conditions of pressure and temperature.
[0084] The condenser 31 is thermally coupled with the evaporator 23
of the second hydraulic circuit 2 in such a way that heat released
by the third operating fluid at the condenser 31 may be transferred
to the second operating fluid at the evaporator 23.
[0085] Advantageously, in this embodiment the second and the third
hydraulic circuit 2, 3 in a heat exchange relationship with one
another as described, overall define a dual-stage compression heat
pump unit, capable of producing heat at high temperature (in
correspondence of the condenser 21) as well as with very low
evaporation temperatures of the (third) operating fluid (in
correspondence of the evaporator 33). This unit is therefore
particularly suitable to a thermal coupling with an absorption heat
pump cycle or, in general, with a combined heat pump cycle, for
supplying the heat necessary for the process of separating the
operating fluid from the solution, which, in the embodiment of the
invention here described, takes place in the generator 10.
[0086] Furthermore, this embodiment enables the production of
refrigerating power at both the evaporator 13 of the first
hydraulic circuit 1 and at the evaporator 33 of the third hydraulic
circuit 3. In other words, the evaporator 13 and the evaporator 33
may be thermally coupled to a cooling circuit wherein a cooling
fluid circulates by means of the refrigerating power generated by
the two evaporators. This circuit has been indicated schematically
by a dashed line in FIGS. 3a and 3b. As illustrated, the evaporator
13 of the first hydraulic circuit 1 and the evaporator 33 of the
second hydraulic circuit 2 may separately cool the operating fluid
in accordance with substantially in-parallel operation. In summary,
each of the two evaporators (33 and 13) cool a corresponding load
of the operating fluid. The loads may be collected in a collector,
the outlet of which is assigned for consumption. Alternatively, the
two evaporators 33, 13 might cool the operating fluid in series or
it could be cooled first by one exchanger and then by the
other.
[0087] Furthermore, this third embodiment of the systems (FIGS. 3a
and 3b) advantageously allows thermal power to be produced at two
different temperatures respectively in correspondence of the
absorber 14 and in correspondence of the condenser 11 while
maintaining elevated COPs. The thermal power at relatively low
temperature recovered from the absorber 14 may be used, for
example, for heating of a service fluid (for example domestic hot
water), for dehumidification, etc. The thermal power at relatively
high temperature recovered from the condenser 11 may furthermore be
used for heating of a service fluid. In this regard, in FIG. 3 the
dash-dot-dot lines drawn through the absorber 14 and through the
condenser 11 are intended to indicate the exchange of heat with an
operating circuit in which there circulates a service fluid.
[0088] Moreover, the thermal coupling between the condenser 31 of
the third hydraulic circuit 3 with the evaporator 23 of the second
hydraulic circuit 2 can be achieved in practice by producing these
components with an integrated design, as shown schematically in
FIGS. 3a and 3b, or with components that are separate and
positioned in a heat exchange relationship by means of an
intermediate hydraulic circuit (not shown in the drawings).
[0089] FIGS. 4a and 4b show a fourth preferred embodiment of the
heat pump system 100. This embodiment differs from the third
embodiment illustrated in FIGS. 3a and 3b described above in the
configuration of the second hydraulic circuit 2, to which the
absorber 14 of the first hydraulic circuit 1 is also hydraulically
connected in this case. In particular, the absorber 14 is connected
in the second hydraulic circuit 2 between the evaporator 23 and the
compressor 25.
[0090] In this way it is advantageously possible to achieve two
different modes of operation with the same equipment, according to
whether the compressor 35 in the third hydraulic circuit 3 is
switched on or off. In particular, if the compressor 35 is on, and
therefore the compression heat pump cycle in the third hydraulic
circuit 3 is switched on, the mode of operation of this embodiment
coincides substantially with that achievable with the third
embodiment described above (FIGS. 3a and 3b) of the heat pump
system 100. Furthermore, in this case the second operating fluid
may undergo further heating prior to compression due to passage
into the absorber 14. If, however, the compressor 35 is switched
off, and the compression heat pump cycle in the third hydraulic
circuit 3 is therefore not active, the operating mode of this
embodiment coincides with that possible with the first embodiment
(FIGS. 1a and 1b) described above of the heat pump system 100.
[0091] In all the embodiments described above, depending on the
fluid type selected as the first operating fluid, to produce the
absorption heat pump cycle within the desired temperature interval
it may be necessary to use pressures lower than atmospheric
pressure. In this case, the first hydraulic circuit 1 must be
produced with a watertight seal. The desired degree of vacuum can
be created by means of an external vacuum pump, temporarily
connected to the first hydraulic circuit 1, or also by means of a
dedicated vacuum pump integrated into the heat pump system 100 of
the invention. This second solution may be advantageous in the case
of large-scale installations and/or in case of a foreseeable need
for periodic changes in the operating conditions of the absorption
heat pump cycle.
[0092] It is also observed that in all the embodiments described
above of the heat pump system according to the invention, the
compression is provided only for the second circulating fluid of
the second circuit 2. In other words, the integration of the first
hydraulic circuit 1 with the second hydraulic circuit 2 according
to the invention advantageously does not require the compression of
the vapours circulating in the first hydraulic circuit 1. This
translates into a notable simplification of the heat pump system
under the technological profile. Moreover, by comparison with the
known solutions which provide for compression of the vapours in the
material system, the solution according to the invention is both
more reliable and simplifies the maintenance and control
operations.
[0093] With reference to FIGS. 5-7, preferred embodiments of the
method for cooling and/or heating in accordance with the present
invention will now be described, which embodiments are
implementable by means of the heat pump system 100 described
above.
[0094] In this case also, for the sake of clarity reference will be
made to embodiments of the method the invention wherein the
combined heat pump cycle is in particular an absorption heat pump
cycle wherein the material system which the first operating fluid
forms with the auxiliary substance during part of the said cycle is
a liquid solution.
[0095] FIGS. 5-7 show schematically in the form of block diagrams
those components of the heat pump system 100 described above that
are involved in the exchanges of energy both internal to the system
(dashed arrows) and with the external environment (solid arrows)
and which are important for the description of the methods of the
invention and for the advantages thereof. Substantially passive
components have therefore been omitted, for example the expansion
device, the components having a relatively negligible influence
within the complex energy balance of the heat pump system 100, such
as for example the circulating pumps, the electrical energy
consumption of which is negligible by comparison with that of the
compressors.
[0096] In such figures, the components shown of the heat pump
system 100 are arranged at different levels with respect to a
temperature scale, to visually indicate the different temperatures
within the ambit of which the respective heat exchangers are
possible.
[0097] Furthermore, the components are grouped into columns
according to the cycle in which they operate. In particular, in the
right-hand column shows the components which operate within the
absorption heat pump cycle and in which the first operating fluid
circulates alone, that is the condenser 11 and the evaporator
13.
[0098] The middle column shows the components which operate within
the absorption heat pump cycle and in which the first operating
fluid circulates in solution with the auxiliary substance, that is
the generator 10 and the absorber 14. Finally, in the left-hand
column the components which operate within the compression heat
pump cycles are represented, that is the condenser 21, the
evaporator 23 and the compressor 25 and, where applicable, the
condenser 31, the evaporator 33 and the compressor 35.
[0099] In a first step of the cooling and/or heating method of the
invention, an absorption heat pump cycle is performed by means of a
first operating fluid capable of forming a solution with a
predetermined auxiliary substance. This step may be activated by
means of the first hydraulic circuit 1 of the heat pump system 100
described above.
[0100] In greater detail, this step comprises: separating at least
a fraction of the first operating fluid from the solution formed
with the auxiliary substance in correspondence of the generator 10;
at least partially condensing the first operating fluid which has
been separated in correspondence of the condenser 11; at least
partially evaporating, in correspondence of the evaporator 13, the
first operating fluid which has been condensed and then subjected
to expansion in the expansion device 12; passing the first
operating fluid which has been evaporated again into solution with
the auxiliary substance at the absorber 14.
[0101] In a second step of the method, at least in part
simultaneous with the first step, a compression heat pump cycle, a
compression heat pump cycle is carried out by means of a second
operating fluid. This step may be implemented by means of the
second hydraulic circuit 2 of the heat pump system 100 described
above.
[0102] In greater detail, this step comprises: at least partially
condensing, in correspondence of the condenser 21, the second
operating fluid previously compressed by means of the compressor
25; evaporating, in correspondence of the evaporator 23, the second
operating fluid which has been condensed and then subjected to
expansion in the expansion device 22.
[0103] In a third step of the method, at least in part simultaneous
with the first and the second steps described above, the heat
released by the second operating fluid during condensation in the
compression heat pump cycle is transferred to the solution within
the absorption heat pump cycle to perform the separation of at
least a fraction of the first operating fluid from the solution
(see arrow H1 in FIGS. 5-7).
[0104] This step may be performed within the heat pump system 100
of the invention due to the thermal coupling already described
between the condenser 21 of the second hydraulic circuit 2 and the
generator 10 of the first hydraulic circuit 1.
[0105] The temperature of condensation TC2 of the second operating
fluid within the compression heat pump cycle is preferably within
the range from approximately 70.degree. C. and approximately
95.degree. C., more preferably between approximately 75.degree. C.
and approximately 85.degree. C.
[0106] Because the passage of the first operating fluid into
solution with the auxiliary substance in the absorption heat pump
cycle--or, more generally, incorporation thereof into the material
system in a combined heat pump cycle--is typically an exothermic
process, in a first preferred embodiment thereof shown in FIG. 5,
the method of the invention may furthermore comprise the fourth
step, at least in part simultaneous with the preceding steps
described, of transferring heat released in the absorption heat
pump cycle--following the passage of the first operating fluid into
solution--to the second operating fluid during the evaporation of
the latter in the compression heat pump cycle (see arrow H2 in FIG.
5).
[0107] This step may in particular be implemented by means of the
embodiments of the heat pump system 100 of the invention that have
been previously described with reference to FIG. 1a, 1b, as well as
FIGS. 4a, 4b in the case in which the compressor 35 is switched
off, thanks to the thermal coupling between the absorber 14 of the
first hydraulic circuit 1 and the evaporator 23 of the second
hydraulic circuit 2.
[0108] The heat released following the passage into solution of the
first operating fluid in solution is typically available at
temperatures within the range of approximately 35.degree. C. to
approximately 55.degree. C.
[0109] In this preferred embodiment of the method of the invention,
in the face of the expense of electrical power (arrow E1) for the
operation of the compressor 25 of the second hydraulic circuit 2,
the following may be achieved as a useful effect, together or
alternatively: the production of refrigerating power (arrow C1) in
correspondence of the evaporator 13 and of thermal power (arrow H3)
in correspondence of the condenser 11 of the first hydraulic
circuit 1. Therefore, the following COP values may alternatively be
obtained, in this case with the heat pump system 100:
COP.sub.1=(H3+C1)/E1;
COP.sub.2=H3/E1;
COP.sub.3=C1/E1.
[0110] According to a second preferred embodiment of the method of
the invention, shown in FIG. 6, in place of the fourth step
described above, it is provided a step of transferring heat
released from the first operating fluid during condensation in the
absorption heat pump cycle to the second operating fluid during
evaporation of the latter in the compression heat pump cycle (see
arrow H3 in FIG. 6).
[0111] This step may in particular implemented by means of the
embodiments of the heat pump system 100 of the invention previously
described with reference to FIGS. 2a, 2b, thanks to the thermal
coupling between the condenser 11 of the first hydraulic circuit 1
and the evaporator 23 of the second hydraulic circuit 2. In this
embodiment, the temperature of condensation TC1 of the first
operating fluid of the absorption heat pump cycle is preferably
within the range from approximately 40.degree. C. to approximately
70.degree. C., more preferably between approximately 50.degree. C.
and approximately 60.degree. C.
[0112] Advantageously, the evaporation of the second operating
fluid in correspondence of the evaporator 23 may thus take place at
temperatures correspondingly higher as compared with those reached
in other embodiments of the methods of the invention, by which, the
other conditions being equal, the jump in temperature in the
compression heat pump cycle is reduced with a consequent increase
in COP.
[0113] In this preferred embodiment of the method of the invention,
in the face of the expense of electrical power (arrow E1) for
operation of the compressor 25 of the second hydraulic circuit 2,
the following may be achieved as a useful effect, together or
alternatively: the production of refrigerating power (arrow C1) at
the evaporator 13 and the production of thermal power at
intermediate temperature (arrow H2) at the absorber 14 of the first
hydraulic circuit 1.
[0114] Therefore, the following COP values may alternatively be
obtained, in this case with the heat pump system 100:
COP.sub.4=(H2+C1)/E1;
COP.sub.5=H2/E1, as well as still
COP.sub.3=C1/E1.
[0115] In a third preferred embodiment, shown in FIG. 7, the method
of the invention further comprises a fifth and a sixth step, at
least in part simultaneous with the steps described above.
[0116] In particular, in the fifth step of the methods are further
compression heat pump cycle is carried out by means of a third
operating fluid. This cycle is analogous to the compression heat
pump cycle described above with reference to the second step of the
method, but is carried out within a reduced temperature
interval.
[0117] In the sixth phase of the method, the heat released by the
third operating fluid, during the condensation in the said further
compression heat pump cycle, is transferred to the second operating
fluid during the evaporation of this latter in the compression heat
pump cycle (see arrow H4 in FIG. 7).
[0118] Advantageously in this way, the two compression heat pump
cycles are thermally coupled so as to produce a dual-stage
compression heat pump cycle.
[0119] These further steps may in particular be performed by means
of the embodiments of the heat pump system 100 of the invention
previously described with reference to FIGS. 3, 3b, as well as
FIGS. 4, 4b when the compressor 35 is active, thanks to thermal
coupling between the condenser 31 of the third hydraulic circuit 3
and the evaporator 23 of the second hydraulic circuit 2.
[0120] The temperature of condensation TC3 of the third operating
fluid in said further compression heat pump cycle is preferably
within the range from approximately 30.degree. C. and approximately
60.degree. C., more preferably between approximately 35.degree. C.
and approximately 50.degree. C.
[0121] In this preferred embodiment of the method of the invention,
in the face of the expense of electrical power for the operation of
the compressor is 25 and 35 (arrows E1, E2) respectively in the
second 2 2/3 3 hydraulic circuit, the following useful effects may
be achieved, together or alternatively: the production of
refrigerating power both in correspondence of evaporator 13 (arrow
C1) of the first hydraulic circuit 1 and of the evaporator 33
(arrow C2) of the third hydraulic circuit 3, the production of
thermal power at an intermediate temperature in correspondence of
the absorber 14 (arrow H2) of the first hydraulic circuit 1 and the
production of thermal power at a higher temperature at the
condenser 11 (arrow H3) of the first hydraulic circuit 1.
Therefore, in this case with the heat pump system 100, the
following COP values may alternative it be obtained:
COP.sub.6=(C1+C2+H2+H3)/(E1+E2);
COP.sub.7=(H2+C1+C2)/(E1+E2);
COP.sub.8=(H3+C1+C2)/(E1+E2);
COP.sub.9=(C1+C2)/(E1+E2);
COP.sub.10=(H2+H3)/(E1+E2);
COP.sub.11=H2/(E1+E2);
COP.sub.12=H3/(E1+E2);
COP.sub.13=C1/(E1+E2);
COP.sub.14=C2/(E1+E2).
[0122] The first operating fluid and the respective auxiliary
substance for the combined heat pump cycle, the second and the
third operating fluid in the two compression heat pump cycles and
the heat-conductive fluids for intermediate hydraulic circuits as
necessary interposed between the thermally coupled units as
described above may be selected by the person skilled in the field
from among those known on the basis of specific application
requirements.
[0123] Still on the basis of specific application requirements, the
person skilled in the field will be able to select the second and
the third operating fluid identical or different from one
another.
[0124] In the case wherein the combined heat pump cycle is in
particular and absorption heat pump cycle, water and lithium
bromide respectively are preferably selected as the first operating
fluid and auxiliary substance.
[0125] For the compression heat pump cycle(s), R600 (n-butane) is
preferably selected.
[0126] For the intermediate hydraulic circuits which may be
present, diathermic fluids or water are preferably selected.
* * * * *