Note: Descriptions are shown in the official language in which they were submitted.
l.'ZZ~ 4
1 TI~L~: A~SORPTION REFRIG~RATIO~ EAT PU~P SYS~EM
S~IARY 0~ T~E INVE~TION-
This invention relates to an absorption
refrigeration/heat pump system which comprises a higner
temperature subsystem ana a lower temperature su~system with
various components of the subsystems in heat exchange
relationship with one another to provide greater performance
than usually obtainable in such systems and/or ~o permit the
use of fluids that have been unsatisfactory in conventional
systems~ ~ore particularly, it relates to an absorption
refrigeration or heat pump system comprising a higher
temperature subsystem and a lower temperature SuDSyStem in
which the higher temperature condenser is in a heat exchange
relationsnip with the lower temperature desorber an~ the
heating and/or cooling loads are arrangea to exchange heat
with various combinations of the other components of the
system
Briefly and in summary, the invention comprises an
absorption refrigeration and heat pump system constructed to
provi~e heat to or remove heat from a load when the ambient
heat sink or source of heat is aDove about 45F comprising
at least one first subsystem for operation at higher
temperature and at least one second subsystem for operation
at lower temperature relative to the first subsystem, each
subsystem having components of absorber means, desorber
means, con~enser means, ana evaporator means operatively
connectea together, with a conaenser means of the higher
temperature subsystem in heat exchange relatlonsnip witn the
desorber means of the lower temperature subsystem; with the
evaporator of the higher temperature subsystem ana the
evaporator of the lower temperature subsystem in series heat
excnange relationship with the load in the cooling moae or
with the ambient in the heating moae; ana with the absor~er
. r4~
~;~2~
l of the higher temperature subsystem, the condenser of the
lower ~emperature subsystem, and the absorGer of the lower
temperature subsystem in series heat exchange relationshi~
with the sink in the cooling mode and the loaa in the
heating mode
When operated with the heat sink or source of heat
below 45F, the evaporator of the higher temperature
su~system is placed in heat excnange relationship with the
conaenser of the lower temperature subsystem and n,eans is
providea to balance the system.
An aaditional feature of the invention includes means
to pump li~uid refrigerant from the conaenser of the higner
temperature subsystem to the desorDer of the higher
temperature subsystem to balance the evaporator of the
higher temperature subsystem heatins requirement with tne
heating requirement of the condenser of the lower
temperature subsystem.
Absorption refrigeration and heat pump systems are well
known and their basic operating characteristics need little
further aescription except to establish the definitions and
context in which this invention will be later aescribed
In a typical system water is a refrigerant dissolved in
a lithium bromide/water solution, often called the "solution
pair"~ Water is absorbea in the lithium bromide solution to
varying degrees throughout the sytem and the heat of
absorption is added or extractea to produce heating ana
cooling effects
The solution pair enters a generator where it is
subjected to heat~ The appliea heat aesorbs the refrigerant
water in the form of vapor which is conveyed to the
condenser. There, external ambient cooling condenses the
water vapor to liquid, which is conveyea through an
expansion valve, into an evaporator where neat is absorbed.
In the refrigeration system the heat absor~ed in the
evaporator is from the cooling loaa~
~z~
1 The lo~- pressure vapor then Qasses to an absorber where
ambient cooling allows the lithium bromide solution to
absorb the water vapor The solution pair is then conveyea
to a recuperator by a pu~,p The recuperator is a counter
flow heat exchanger where heat from the absorbent, li~hiurr,
bromiae~water solution, flowing from the generator to the
absorber, heats the returnins solution pair flowing from the
absorber to the generator In the heating cycle, the
cooling appliea at the absorber and/or the condenser is the
heat delivery to the heating loaa
As a matter of convenience and terminology, each ~art
of the aborption system, which operates at the same
pressure, is termed a chamber
Conventional absorption refrigeration anà heat systems
are two-chamber systems~ ~hen operated as a heat pump they
give respectable heating performance but give extremely poor
cooling performance Using ammonia (N~3) as the refrigerant
and water (H20) as the sorbent, heat pumping can occur from
an ambient air source which is at temperatures below
freezing. In a theoretical assessment where the air is
treated as if it were dry so that no aefrosting is
necessary, t~e typical two chamber NH3/~2O heat pump would
represent a significant improvement over what would be
expected of a simple furnace However, since heat pumps are
more expensive than a furnace, cooling season performance
benefits are needea to justify the aaaed expense. In other
words, the heat pump must act as an air conditioner also to
offset the cost of a separate installation of an air
conaitioner with the furnace For cooling, an NH3~2u
system is predicted to have a performance factor, PF (PF =
cooling effect/combustion heat input) equal to aDout 0~46.
This low performance index causes unreasonable fuel (or
ener~y) costs from excessive fuel (or energy) use This low
performance of the ammonia/water system results from the
poor performance characteristics of the ammonia/water
solution at the higher temperature ranges if the heat is
3 ~Zl~
1 supplied to the absorption system at higher ~emperatures
Three-cham~er systems of various types have been
suggested which would improve the performance Dy staging the
desorption process into effects. T~lis woulQ allow for
increasing the actual tempeeature in which the ariving heat
is aaded to the system (cycle)~ The reference Carnot cyc'e
efficiency would be increased and the real cycle would
follow suit~ However again this increase in temperature
would represent an unreasonably high pressure foc
ammonia/water systems anà woula force the system to operate
in regions for which aata is not readily available.
Extrapolations estimate a peak cycle temperature of about
400F for an air conditioning case with a 35F evaporator
and much higher for a heat pump case with a lower evaporator
temperature.
In aadition the pressure ano toxicity tena to rule out
ammonia/water in a three-chamber system. The search for
organic material such as halogenatea hyarocarbons ana other
refrigerants as a replacement for the ammonia has been
limitea by fluid stability at these higher temperatures.
Normal organic refrigerant stability tests anticipate that
it is necessary for oil to be present for opera~ion in vapor
compression refrigeration systems. These high operating
temperatures rule out most of the common refrigerants,
particularly when being heated directly by combustion
products which often cause local hot spots, which result in
working fluid degradation and/or corrosion of components~
The subsystem of this invention employes four char,bers
Two chambers are operatively connectea in one two-chamcer
subsystem ana two other chambers are operatively connectea
in another subsystem.
One subsystem employes a higher temperature solution
pair having good higher temperature performance properties,
preferably lithium bromide/water with water as the
refrigerant ana lithium bromide as the absorbent. The other
subsystem employes a aifferent solution pair, preferably
12Z~
1 ammonia/water, with ammonia as the refri~erant ana water as
the a~sorbent, The first mentionea su~system is operatea at
higher temperatures and the system configuratiGn allows the
pair to be selectea to avoi~ freezing ana cr~stalization
proble~s, The other, secona, s~bsystem employes a lower
temperature solution pair having yood low te,nperat~re
perfomance properties and is operated at lower temperatures
in the ranse wnere an oryanic shouia be expectea to operate
successfully without toxicity corrosion or stability
problems and where t~mperatures below freezing are
acceptable,
The first subsystem ana the secona subsystem; i,e,,
higher ten~perature and the lower temperature subsystem
respectively, are operatively combinea anà connected by
placing the higher temperature condenser in heat exchange
relationship with the lower temperature aesor~er with other
conlponents of the total system also combinea in a new and
novel way as will be later described,
In the prior art, others have associated various
components of absorption refrigeration/heat pump systems in
various ways with the purpose of improving the performance
or otherwise enhancing the operation of these systems, These
other prior art systems have met with varying aegrees of
success but have apparently not obtained all objectives and
are capable of further improvement as proviaed by this
invention,
In the prior art, U, S, Patent 2,350,115 - Katzaw
describes what may be termed a four-chamber system that
employes some of the characteristics o~ the applicant's
3G invention but which fails to recognize the advantages of
proviains an arrangement that recombines and reairects the
heating and cooling effects of the uncontrolled amDient
atmosphere, as well as the controlled/ conditioned
atmospheres or loaas,
3~4
1 ~ S Patent 3,4~3,710 - ~earint, is another exa~.ple oi
a prior art version of a four-cnamber system that combines a
higher temperature subsystem with a lower temperature
subsystem As aisclosed in the previous patent to ~atzaw,
although the advantage of placing the higher temperature
conaenser in heat exchange relationship with lower
temperature aesorber is revealed, tne interrelationships
between other components are not the same or arranged to the
same advantage as the applicant's invention This is
especially to be noted in connection with the arrangement of
various elements with regara to ambien~ atmosphere
conditions ana the conditioned atmosphere/or loa~
It is a purpose of this invention to comoine the
co~ponents of the separate subsystems of the four-chamber
1~ system to provide an absorption refrigeration and/or heat
pump total system that is capable of either a higher
coefficient of performance or of being manufacturea with
efficiencies without reàucing performance, and without
resorting to continued search for an ideal fluid pair.
Other objectives ana features of the invention will be
apparent and unaerstood from the detailed description anà
the accompanying drawings wnich follow
l.~Z'~
1 DESC~IPTIO~ OF THE DRA~INGS
Figure 1 is a schematic representation of the
arrangements of the various components of the system of this
invention in the air conditioning and warm ambient neat pump
mode of operation
Figure 2 is a schematic representation of the various
components of the system of this invention in the cold
am~lent heat pump moae of operation~
Fig~re 3 is a schematic representation of the various
components of the system of this invention in another
embodiment of the cold ambient heat pump mode of operation.
Fiyure 4 is an air flow diagram of the various
- components of the system of this invention when operated in
the air conditioning mode shown in Figure 1.
15Figure 5 is an air flow diagram of the various
components of the system of this invention when operated in
the warm heat pump mode shown in Figure l
Figure 6 is an air flow diagram of the various
components of the system of this invention when operated in
the moae shown in Figure 2.
Figure 7 is an air flow aiagram of the various
components of the system of this invention when opera~ed in
the moae shown in Figure 3
Figure 8 is a P-T-x diagram illustrating the
thermodynamic operation of the system when operated in the
moaes shown in Figure 1~
Figure 9 is a F-T-x aia~ra~. illustratin~ the
thermoaynamic performance of the system when operated in the
modes shown in Figures ~ ana 3~
DETAILED DESCRIPTION OF THE INVENTION
In a aescription of this invention, it is important
that clear distinction be made between solutions entering
ana leaving various components. Therefore, adopted herein
is the notation of the standard setting body on absorption
systems in the U~ S~, the ASHRAE Technical Committee (8.3)
on Absorption ~achines~ Their notation is given in the
~Z211~
d
1 following quote from the ASHRAE 1979 Equipment ~andDook,
Cha~ter 14:
"To avoid confusion of terminology in the
absorption field, AS~RAE Technical Committee
(~.3) recommenas the following standaraizea
terms for the absorDent-refriseran~ solution.
Weak absorbent is that solution which has
picked up refrigerant in the absorber and is
then weak in its affinity for refrigerant
Strong a~sorbent is that solution which
has had refrigerant driven from it in the
generator and, therefore, has a strong
affinity for refrigerant "
In the schematic representation o~ Figure 1~ the
hexagonal blocks represent the components of the first
subsystem of the invention and the circles represent the
components of the second subsystem~ The first subsystem may
~e interchangeably termed the "high" subsystem and the
second, the "low" subsystem. Components of each may be
termed in the same manner, respectively
In the preferred embodiment of the invention, in the
first (high) subsystem the water is the refrigerant and
lithium bromide (LiBr) is the absorbent.
The higher temperature desorber 30 of the first
su~system is heatea by a flame 31 or other means such as
electricity. The desorber 30 is connected by a suitable
conduit 32 to a higher temperature condenser 33 The conduit
32 carries superheated refrigerant vapor to the condenser
33. Heat extracted from the con~enser causes the
refrigerant to conaense to a liquid.
The condenser 33 is connected to an expansion valve 34
Dy a conauit 35 which carries the conaensea liquid
refrigerant~
Expansion valve 34 is connectea to a high evaporator 36
where the low pressure refrigerant vaporizes ~s it extracts
heat from the ambient surroundings The vaporized
l refrigerant is conveyed by conauit means 37 to a high
abso~ber 38 where it wea~ens the strong solution suppliea to
the aosorber 38 from conduit 43 through expansion valve 42
In the nigh subsyste~" the desorber 30 is connected to
5 a recuperator 40 by conduit means 41 The recuperator 40 is
connected to an expansion valve 42 ana to the absor~er 3~ by
a conàuit ~eans 43 The absorber 38 is connectea through a
pump 44 to the recuperator 40 by a conduit means 45 ana ~he
recuperator 40 is connectea back to the aesorber 3C by a
conduit ~eans 46 In this part of the subsystem strons
absorbent solution is carried from the desorber 30 through
the recuperator 40 to the absorber 38 where it absorbs
refrigerant ana the resulting weak solution is pumpea
through the recuperator 40 to the desorDer 30. Heat is
exchanged between the strong absorbent and the weak
absorbent solutions in the recuperator 40.
In the above described manner the two-chamDer I,II,
higher temperature, first subsystem operates in a typical
generally conventional manner.
The solution pair used in chambers III and IV of the
second (lower temperature) subsystem is prefecably ammonia
ana water, with ammonia as the refrigerant and water as the
sorbent.
Combined with the conaenser 33 in heat exchange
relationship is a desorber 50 which is connected to a
conaenser 51 by conduit means 52. Conduit 52 may include
rectifier sections as typically needea when a volatile
sorbent, such as water, is usea in a lower tem~erature
solution system, comprising chambers III and IV.
Condenser 51 is connected through an expanslon valve 53
to an evaporator 54 by a conauit means 55. Evaporator 54 is
connecteà to an absorber 59 by a conduit means 56 ana the
exit from the aesorber 50 is connected to recuperator 56 by
a conauit 57 whicn continues through an expansion valve 58
to the absorber 59. Through a pump 60 r the exit from the
absor~er 59 is connectea through the recuperator 56 to the
~2~ 4
1 desorber 50 tnrough conduit means 61~
In operation, ammonia refrigerant vapor is driven from
the desorber 5~ by heat from the conàenser 33 ana passes
through the cona~it means 52 to the condenser 51. In
condenser 51 heat is given up to a cooling medium, and the
liquic refrigerant is carried to the expansion valve 53
where it expands into the evaporator and becomes vapor as it
receives heat from an external source. The re~rigerant
vapor is carried to the absorDer 59 where heat is given up
to a sink and refrigerant is absorbea in a strong absorDent
solution supplied to the absorber S9 from expansion valve
5~ The weakened absorbent solution is pumpea Dac~ to the
desorber 50, being warmed by heat exchange in the
recuperator 56~
Throughout the continuea aetailea description, the
invention is described in the context of refrigeration and
heat pumping for the purpose of heating ana cooling the
environmental atmosphere of living space in a building or
other shelter~ This "heating and air conditioning"
application of the invention is an essential and impor~ant
use but it should be understood that in the broader sense
the invention may be applicable in any circumstance where
cooling or heating is desired and it may be aavantageous to
use an a~sorption multi-purpose system.
Air Conditionin Mode of Operation
In the air conditioning moae high evaporator 36 and the
low evaporator 54 are connected in series heat excnange
relationship with the flow of air from the conditioned
livins space environment (the load)
As shown in Figure 1, components operating at higher
temperatures are snown to tne right and components operating
at lower temperatures are shown to the left, relative to
eacn other. The loaa is progressively cooled as it passes
across the evaporators 36 and 54 respectively~ As shown in
Figure 4, a fan 120 draws air from a living space return
auct 121, and with dampers 122 and 124 in the "A" position,
i~Z~
1 forces Lhat air throu~h a duct 123 to the high evaporator
36 hith aampers 127 ~na 128 in the "~" position, house air
leaves evaporator 36 and passes through a duct 126, low
evaporator 54, ana a àuct 12~ from which it is returnea to
the conaitioned living space.
Outside air is drawn into the system through a duct
101 t and with a damper 102 in the "A" position, throuyh duct
103 to high absorber 3~. Damper 106 isolates the outsiae
air inlet duct 103 from the interior plenum 125 to nigh
10 evaporator 36. Flow continues through duct 112 to the low
absorDer 59, duct 113, ana low conaenser 51 to duct 11~
Damper 109 placed in the "A" position connects auct 114 with
the discharge duct 110 which contains the fan 111, that
induces the flow of outsiae air.
As seen in Figures 1 and 4, heat from the absorber 38,
condenser 51, and absorber 59 is re~ected to the outside air
(the heat sink) by means of the air flow pattern establishea
across these ~omponents.
Referring to Figures 1 and 8, in the air conditioning
mode of the preferred emboadiment, a saturation temperature
of 254F establishes the pressure at 32 psia for operations
in chamber I. The desorber 30 receives weak absorbent
solution (57 % LiBr.) after being heatea in the recuperater
40 by the strong absorbent solution leaving the desorber 30
25 at 60~ Li~r ana 363F. In the total system in this moae~
only the desorber 30 receives heat from the external source
31.
Saturation conaitions at the evaporator 36 esta~lish
the pressure of 0.18 Psia and a temperature 50F In the
absorber 38, the strong absrobent solution enters at a
temperature of 121F and 60% LiBr equilibrium condition.
Heat is rejected to the heat sink which in an air
conditioning system, may be the outside ambient atmospnere.
Because the solution pair has been selected for its
performance under these conditions, operations are below tne
crystalization limit and especially aàvantageous for the
12
1 heat exchange relationship between the conàenser 33 ano the
desorber 50.
A saturation tempera~ure of 140F in condenser 51
esta~lisnes the pressure at 350 Psia for operations in
chamber III with NH3/H2O as the lower temperature fluid
pair The desorber 50 receives weak absorbent solution
(42 8% NH3) at a temperature of 237F ana the desorber 50
receives heat from the condenser 33
Saturation conaitions at the evaporator 54 establishes
the pressure at 71 psia at temperature 40F. The absorber
59 receives strong solution at 39 ~% ~H3 ana a temperature
of 131F, discharges weak solutiorl at approximately 121F,
ana gives up heat to the heat sink in heat exchange
relationship
The theoretical performance of this cycle is preaictea
to be: COP = 0.96. Taking loses into the account, the actual
coefficient of performance is estimated to be 0 8~ with a
high performance combustor 31
Warm Ambient Heat Pump Operation
When the outside ambient air conaitions are about 45F
and above, heat pump operations are carried out in the same
system except that the roles of the ambient and load are
reversed as shown in Figure 5 for a system which is heating
or air conaitioning.
With dampers 122 ana 109 in the "B" position, return
air from the living space supplied by fan 120 is aiverted to
duct 103, high absorber 38, low absorber 59, ana low
condenser 51 and then returned to the conditionea air exit
duct 129~ With dampers 102 and 128 also in the "B"
position, outside air passes from inlet 101 through high
evaporator 36 ana low evaporator 54 before being arawn to
exit duct 110 by fan 111. Dampers 124 ana 127 remain in the
"A" position ana da~,per 106 remains closea.
In this circumstance, the ambient outside air as a
source of heat is causea to flow across the evapora~ors 36
ana 54 which are arrangea in series heat exchange
211~
1 relations~i,? with the air passing across the evaporator 36
of the hisner temperature su~system first. Retaining the
series nature of the flow of air across the two evapo~ators
allows the outside air to oe cooled to temperatures Delow
freezing without freezin~ the higher temperature evaporator
At the same time, imposing the return air from the livins
space atmosphere on the high absor~er first allows it to be
operated away from crystalization region. Subsequent hea~ins
of the living space atmosphere by the aDsorber 59 and the
con~enser 51 can be at higher temueratures to n,inimize the
flow of livin~ space air.
Theoretical analysis for this moae and example
establishes that, for every unit of heat supplied by the
combustion proaucts, 0.96 units of heat can be supplieà from
the ambient air~ When adjusted for its stack loses, the
coefficient of performance is equal to or greater than 1.7.
Cold Ambient Heat_Pump Operation
At outside ambient air temperatures lower than about
45F, it is not acceptable to use the higher temperature
evaporator 36 to extract heat from the outside air without
freezing up the higher temperature refrigerant flow with a
H~O/LiBr higher temperature system. To protect the higher
temperature evaporator 36 from freezing (ana the higher
temperature absorber from crystalization) this heat pumping
cycle is carried out by imposing re]ection heat from the
lower temperature subsystem upon the higher temperature
evaporator 3~.
Referring to Figure 2, the system is configurea
schematically the same as in Figure 1 except that the
evaporator 36 is in hea~ exchanse relationship with the
conaenser 51 . This is accomplishea by causing the air flow
to pass across these components as shown in Figure 6. In
oraer to accomplish this, the ducting configuration is
modified as shown in Figure 6~
- ~'2~ 4
14
1 Camper valve 106 is located so that it can isolate the
condenser inlet 113 and evapvrator inlet 125 wnen closec,
but lS shown open in Figure 6, allowing recircula~ion fan
130 to force a separate flow of air from the high evaporator
36 to the low concenser 51. Dampers 124 and 127 and a
damper 104 must ~e in the "B" position an~ a duct 108 must
be added for this recirculation air flow to occur. As in
Figure 5, dampers 102, 109, 122, and 128 remain in the "B"
position.
In adaition, a punlp 65 is connected from the conaenser
33 to the desorber 30 by a conduit means 66, as shown in
Figure 2~
In operation, liquia conaensate is pumpeo from the
condenser 33 to the aesorber 30 by the pump 65 as necessary
to balance the system when the heat rejection from the
conaenser 51 is made equal to the heat aàdition to the
evaporator 36 . Additional heat is supplied by the source
31 to vaporize the additional liquid condensate that is
pumped from the condenser 33 to the desorber 30. This
supplies extra heat to the condenser 33 which matches the
requirements of desorber 50 in this mode of operation~
Referring to Figures 2 and 9, in a preferred example,
the condenser 33 operates at a saturation temperature of
285F (establishing the chamber I pressure at 53.2 psia) as
it gives off heat the desorber 50 operating at a peak
solution temperature of 277F. The desorber 30 receives
weak absorbent solution at 49.2~ Li~r from the recuperator
40 where it is heated by the strong solution leaving the
desorber 30 at 375F and 55.3~ LiBr.
The absorber 38 receives refrigerant vapor at 0.32 psia
from evaporator 36 and strong absorbent solution at 1~5F
and 55~3% LiBr from the recuperator 40. ~s the solution is
coolea by rejecting heat to the air in the livins space (the
load) the leaving solution is at 106F and 49.2% LiBr.
1 The conaenser 51 is assumea to operate at 140F
establishing a pressure of 355 psia in the cham~er II1
The weak absorbent solution enters the desor~er 50 at 24~F
ana ~1 2~ N~3 after being recuperatively heated by the
S strong absorbent solution leaving the aesorbec 50 at 277F
and 33 3% NH3 The air flow heat exchange between tne
condenser Sl and the evaporator 36 establishes the
pressure of chamber II at 0~32 psia. The su~systems are
aajustea so that the heat leavins the condenser 51 is equal
to that acceptea by the evaporator 36
In the typical example system, the evaporator 54 is
assumea to operate at -2.5QF establishing 29 psia as the
pressure in chamber IV. The evaporator 54 extracts heat
from the colà outside air and the surface will need to be
defrosted perioaically. The low absorber 59 operates at ~
psia as it rejects heat to air in the heated living space
(the load). Strong solution enters the absorber 59 at 103F
- ana 33.3~ N~3 and leaves at 77F and 41.2~ NH3.
With the refrigerant flow esta~lished to match the heat
flow between the condenser 51 and the evaporator 36 , the
desorber 50 requires more heat (about one third more in the
example) than woula normally ~e rejected by the conàenser
33. This short fall of energy is suppliea by additional
heat input from the source 31. The energy transfer is
accomplished by additional flow of liquid refrigerant from a
refrigerant well in conaenser 33 to the desorDer 30 driven
by pump 65. In the desorber 30 it is mixed with the
solution supplied by pump 44, accomplishing the desirea
dilution of the solution flow, ana is eventually evaporatea
by the increased heat flow to supply increasea vapor flow to
the condenser 33.
This results in a theoretical heating COP = 1.33 which
would reduce to a value near 1.20 when an aajustment is maae
for stack and other loses in actual practice.
3~4
16
1 From a control point of view, it is aavantageous to De
freea from having to maintain exact heat flow balances at
both the condenser Sl and desorber S0~ The preferre~ methoa
of accomplishiny this is to incluae the evaporator 36 ana
the condenser 51 in the main flow of air to the heated
space as shown in Figure 7~ ~hen balanced, tne evaporator
36 cools the return air ana the high absorber 3~ heats the
return air the same amount so that the mixed temperature
entering absorber S9 from duct 112 is the same as the
temperature in duct 103 When unbalanced, there is a small
net gain or loss in return air temperature entering absorber
59~
In Figure 7, dampers 102, lO9, 122, 124, 127, ana 128
are in the "B" position and damper valve 106 is open just as
in Figure 6. Fan 130 is eliminated and the air flow losses
are reduced.
In the example about 20~ of the heat addea to the first
higher temperature subsystem passes directly to the heated
space without causing any heat pump augmentation through the
~ absorber 38~ Therefore the only true heat pumping process
occurs in the lower temperature secona subsystem in this
combined mode Consequently, it is advantageous to increase
the relative amount of condensate returned to the ~esorber
30 from the condenser 33. Various compromises are possible
in the adjustment of conaensate flow producea by the pump 6~
between these components~ Those skilled in the art will
find it a matter of rou~ine adjustment to determine the
appropriate amount under certain operating conaitions~
Referring to Figure 3, an alternative embodiment of the
cold ambient heat pump operation is schematically shown in
which the heat input to evaporator 36 is virtually
eliminated by closing valve 34 an~ diverting all the
refrigerant flow through a dilution reservoir ~9, and
directing the refrigerant from there through valve 90 to the
inlet to solution pump 44~ This further reduces the LiBr
concentration, increasing the vapor release from the
lZZ~ 4
1 solution pumF flow wlthout excessively broaaenlng tne
concentratlon aifferences across aesorber 30, anu reoucing
the temperature in desor~er 3~ ~s shown in ~lgure 3, some
neat flow passes directly from the heat source 31 to the
conditionea air ~y heat transrer from aDsorDer 3~.
The net coefficient of performance for heating
(C ~ P h) is therefore increasea to about 1.31 This woula
be the preferred emboaiment since it has the potential ~or
the nishest (C~O.P.h).
From the foregoins, it is seen that tne conDlnation of
the various components and their heat exchange relationshi~s
is variable in various com~inations to acnieve an overall
refrigeration/heat pump system havins an unusually hign
C ~P.C for cooling of .o8 ana an unusuaily high C.G.P.h for
heating of at least 1.31, in the cola am~ient heat pum~
moae. These performances are acco~,~lisheà by staging the
first subsystem relative to the second subsystem in
alternative comDinations througn rearrangenlent of the heat
flow in the systenl relative to heat exchange between the
he~t loaa and the heat sink
Figures 4, 5, 6, and 7 show various direct heat
exchange relationships between the components of the
absorption system and the air of the conditione~ space (the
load) and/or the ambient air (the sink or source).
Alternatively, other means may ~e usea to proviae tne heat
exchange in the relationsnips between tnese co~ponents ana
the loaa or sink. For instance, hydronic flow loops ~i.e.,
the use of liquia heat exchange materials such as ethylene
ylycol conveyed in pi~ing between the components ana heat
exchangers in contact witn the loaa or sink) couia replace
any or all of the direct heat exchangers that are ~etween
the elements in the four charl;~ers and the load or the
ambient. In adaition, the pressure flow relationship o~
high eva~orator ana high a~sorber shown in Figure 7 coula
alternatively De a series flow relationship, either airectly
with the conaitioneG space air flow or with tne hyaronic
~zz~
l&
1 flow loops, which delivers heat to the conaitioned space~
It lS herein understooa that although the present
inventior. has been specifically disclosed wlth the preferreà
embodiment and examples, moaification and variations of ~he
concepts herein disclosed may be resorted to by those
skilled in the art Such moaifications and variations are
considered to be within the scope of the invention and the
appenaed claims
