U.S. patent application number 14/233306 was filed with the patent office on 2014-06-19 for method for chilling a building.
This patent application is currently assigned to PURIX APS. The applicant listed for this patent is Christian Holm Fridberg, Lars Munkoe. Invention is credited to Christian Holm Fridberg, Lars Munkoe.
Application Number | 20140165627 14/233306 |
Document ID | / |
Family ID | 46717677 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140165627 |
Kind Code |
A1 |
Munkoe; Lars ; et
al. |
June 19, 2014 |
METHOD FOR CHILLING A BUILDING
Abstract
A method for chilling a building includes the steps of: heating
a working solution contained in a solar panel using solar
radiation, separating the heated working solution in vapor and a
concentrated working solution, condensing the vapor to liquid
refrigerant, evaporating the liquid refrigerant, (i) in a building
to be chilled or (ii) outside a building to be chilled, wherein the
cooling obtained by evaporation is transferred to a cooling liquid
outside the building and transported to the building to be chilled
for delivery of the cooling, absorbing in an absorber the vapor in
the concentrated working solution, and returning the working
solution to the first step.
Inventors: |
Munkoe; Lars; (Kobenhavn O,
DK) ; Fridberg; Christian Holm; (Herlev, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Munkoe; Lars
Fridberg; Christian Holm |
Kobenhavn O
Herlev |
|
DK
DK |
|
|
Assignee: |
PURIX APS
Copenhagen
DK
|
Family ID: |
46717677 |
Appl. No.: |
14/233306 |
Filed: |
July 18, 2012 |
PCT Filed: |
July 18, 2012 |
PCT NO: |
PCT/DK2012/050270 |
371 Date: |
February 26, 2014 |
Current U.S.
Class: |
62/79 ;
62/235.1 |
Current CPC
Class: |
Y02B 30/545 20130101;
F24F 5/0035 20130101; Y02A 30/272 20180101; Y02B 30/54 20130101;
Y02A 30/277 20180101; F24F 2005/0064 20130101; Y02B 10/20 20130101;
F24F 5/0014 20130101; F25B 15/06 20130101; F25B 27/007 20130101;
Y02B 30/62 20130101; Y02A 30/27 20180101; F25B 27/005 20130101;
F24F 1/0007 20130101; Y02B 10/24 20130101 |
Class at
Publication: |
62/79 ;
62/235.1 |
International
Class: |
F25B 27/00 20060101
F25B027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2011 |
DK |
PA 2011 70396 |
Jul 17, 2012 |
IT |
RM2012A000343 |
Claims
1. A method for chilling a building comprising the steps of: a.
Heating an working solution contained in a solar panel using solar
radiation, b. Separating the heated working solution in vapor and a
concentrated working solution, c. Condensing the vapor to liquid
refrigerant, d. Evaporating the liquid refrigerant i. in a building
to be chilled or ii. outside a building to be chilled, wherein the
cooling obtained by evaporation is transferred to a cooling liquid
outside the building and transported to the building to be chilled
for delivery of the cooling, at an evaporation temperature of
6-20.degree. C., e. Absorbing in an absorber the vapor in the
working solution, and f. Returning the working solution to step
a.
2. The method according to claim 1, wherein the heat generated by
the condensing and the absorbing step is removed by a single
fan.
3. The method according to claim 1, wherein the volume for the
working solution in the solar panel of step 1.a is integrated into
the volume of the absorber in step 1.e.
4. The method according to claim 1, wherein the volume of working
fluid in the solar panel may be drained to a reservoir of the
absorber during inoperability of the system.
5. The method according to claim 4, wherein the solar panel is
arranged in a position above the reservoir of the absorber to allow
gravity to transfer the working fluid to the reservoir of the
absorber.
6. The method according to claim 1, wherein the concentrated
working solution in the absorber is distributed by a liquid
distributor through one or more tubes to a counter-flow with the
vapor to allow for an absorption of the vapor, said vapor
distributor being integrated with a reservoir having a volume at
least sufficient for accommodating the volume of the working fluid
in the solar panel.
7. The method in claim 6, wherein the vapor is distributed by a
vapor distributor.
8. The method according to claim 6, wherein the fan is positioned
to deliver an air current to the one or more tube(s) to obtain a
cooling.
9. The method according to claim 6, wherein the vapor distributor
is integrated with the reservoir of the absorber.
10. The method according to claim 1, wherein the liquid volume of
the condenser may be drained to the evaporator.
11. The method according to claim 1, wherein the working solution
is aqueous.
12. The method according to claim 1, wherein the working solution
is a solution of lithium bromide in water.
13. The method according to claim 1, wherein the liquid refrigerant
is evaporated in a building to be chilled at a pressure of 9-24
mbar.
14. The method according to claim 12, wherein the amount of lithium
bromide is 45 to 65% by weight.
15. The method according to claim 1, wherein absolute pressure of
the system is 8 to 120 mbar.
16. The method according to claim 1, wherein the temperature of the
working solution in the upper part of the solar panel is
60-110.degree. C., suitably 75-90.degree. C.
17. The method according to claim 1, wherein the temperature of the
vapor produced by the evaporation of step 1.d is 6-20.degree. C.,
such as 8-16.degree. C., suitably 10-14.degree. C., and optimally
around 12.degree. C.
18. A building chilling system using solar thermal energy,
comprising A solar thermal panel containing an working solution to
be heated by solar radiation, thereby separating the working
solution in a vapor and a concentrated working solution, A
condenser for condensing the vapor to liquid refrigerant, Pressure
reducing means capable of decreasing the evaporation pressure to a
pressure corresponding to an evaporation temperature of
6-20.degree. C., An evaporator positioned i. in a building to be
chilled, ii. or outside a building to be chilled, wherein the
cooling obtained by evaporation is transferred to a cooling liquid
outside the building and transported to the building to be chilled
for delivery of the cooling, and An absorber for absorbing the
vapor from the evaporator in the concentrated working solution.
19. The building chilling system according to claim 18 wherein the
condenser and the absorber is arranged in a common entity.
20. The building chilling system according to claim 19 wherein the
common entity is cooled by a single fan.
21. The building chilling system according to claim 19, wherein
condenser and the absorber in the common entity are positioned
adjacent in parallel for the use of a single fan.
22. The building chilling system according to claim 19, wherein the
condenser and the absorber in the common entity are positioned
adjacent in series for the use of a single fan.
23. The building chilling system according to claim 19, wherein a
funnel is installed between the fan and the common entity to
concentrate the air current.
24. The building chilling system according to claim 18, wherein a
liquid-liquid heat exchanger is arranged in the system for cooling
the concentrated working solution from the solar panel, whereas the
working solution from the absorber is heated.
25. The building chilling system according to claim 18, wherein the
absorber contains a reservoir having a volume capable of containing
the amount of working fluid in the solar panel, recovery heat
exchanger and pipings.
26. The building chilling system according to claim 18, wherein the
solar panel is arranged at a position higher than the reservoir of
the absorber to allow for a drainage by gravity from the solar
panel to the reservoir of the absorber.
27. The building chilling system according to claim 18, wherein the
absorber comprises a liquid distributor for the concentrated
working solution and a vapor distributor connected by one or more
tubes arranged to allow for the concentrated working solution to
flow from the liquid distributor through the tube(s) by gravity to
the vapor distributor in counter-flow with the vapor, said vapor
distributor being integrated with a reservoir having a volume at
least sufficient or accommodating the volume of the working fluid
in the solar panel.
28. The building chilling system according to claim 27, wherein the
one or more tubes are essentially vertical.
29. The building chilling system according to claim 27, wherein the
fan is arranged so that the air current is directed towards the one
or more tubes for allowing a cooling to take place.
30. The building chilling system according to claim 27, wherein the
reservoir of the absorber is integrated with the vapor
distributor.
31. The building chilling system according to claim 1, wherein the
evaporator is connected to the pressure reducing means and/or the
absorber with pipework of a polymeric material.
32. The building chilling system according to claim 31, wherein the
polymeric material is cross-linked polyethylene (PEX).
33. The building chilling system according to claim 18, wherein the
condenser is positioned at a height above the height of the
evaporator to allow for the condenser to be drainable by
gravity.
34. The building chilling system according to claim 18, wherein a
hermetic pump is used for returning the working solution from the
absorber to the solar panel.
35. The building chilling system according to claim 18, wherein
pressure reducing means is a throttle valve.
36. The building chilling system according to claim 18, wherein
pressure reducing means is an orifice.
37. The building chilling system according to claim 18, wherein
pressure reducing means is a capillary tube.
38. The building chilling system according to claim 18, wherein
straight inserts are used in the absorber tubes with the same
length as the absorber tubes.
39. The building chilling system according to claim 38, wherein the
inserts can have any shape and form including bend shape and cross
shape.
40. The building chilling system according to claim 38, wherein the
inserts can have any length.
41. The building chilling system according to claim 18, wherein the
working solution is aqueous.
42. The building chilling system according claim 18, wherein the
pressure reducing means is capable of decreasing the pressure to
9-24 mbar.
Description
INTRODUCTION
[0001] The present invention relates to a method for chilling a
building as well as a building chilling system using solar thermal
energy. The invention aims at providing an improved solar
absorption cooler while reducing resource consumption.
BACKGROUND FOR THE INVENTION
[0002] In warm climate regions or spaces which due to externally or
internally heat sources increase in temperature above acceptable
conditions, the need for cooling arises. The cooled spaces may be
homes, offices, schools, hotel spaces, bungalows, storages rooms,
process areas and applies where condition of space, processes or
goods are required. Therefore, to avoid temperatures that exceed
the comfort zone or acceptable temperature range, a building may
have an air condition unit installed. The most common air condition
unit is a chiller operated by electricity which converts
electricity into a supply of thermal cooling (typically air or
chilled water).
[0003] Where simultaneous presence of the sun and the demand for
cooling is present, an attractive way of providing cooling is to
use a solar chiller unit. A solar chiller system applies the solar
radiation (thermal energy) as main energy input to produce a
chilling effect.
[0004] The collection of solar thermal energy is typically
performed by a solar thermal panel attached to the solar chiller
system via a heat exchanger. The present day solar cooling units
require a relative large material consumption due to heat/cool
storage, moving parts, multiple fans/circulation pumps, multiple
heat exchangers, or the need for evaporation tower as well as dry
cooler. Each of these components is associated with loss of
temperature or loss of energy.
[0005] Specific examples of prior art attempts to produce building
chilling systems are disclosed in WO 2009/093979 A1, U.S. Pat. No.
6,539,738 B2, JP 57073347 A, US 2003041608, US 2005183450, EP
2244039, US 2010251749, and WO 2011/028186 A2.
[0006] It is the object of the present invention to provide a
method and a chilling system, which reduces the temperature and
energy loss, e.g. by reducing the amount of unit operations and
material use, thereby increasing the system efficiency and reducing
the system cost.
SUMMARY OF THE INVENTION
[0007] The present invention relates to method for chilling a
building comprising the steps of: [0008] a. Heating a working
solution contained in a solar panel using solar radiation, [0009]
b. Separating the heated working solution in vapor and a
concentrated working solution, [0010] c. Condensing the vapor to
liquid refrigerant, [0011] d. Evaporating the liquid refrigerant
[0012] i. in a building to be chilled or [0013] ii. outside a
building to be chilled, wherein the cooling obtained by evaporation
is transferred to a cooling liquid outside the building and
transported to the building to be chilled for delivery of the
cooling, [0014] at an evaporation temperature of 6-20.degree. C.,
[0015] e. Absorbing in an absorber the vapor in the concentrated
working solution, and [0016] f. Returning the working solution to
step a.
[0017] According to the present invention, the working solution is
heated in the in the solar panel by radiation from the sun. The
working solution is preferably LiBr/H.sub.2O but other working
pairs such as LiCl/H.sub.2O, CaCl/H.sub.2O, NH.sub.3/H.sub.2O or
similar are applicable and substances for enhancement of heat and
mass transfer or corrosion inhibitors may be added. The supply of
heat generates vapor from the working solution which results in a
concentrated working solution. The vapor is condensed into liquid
refrigerant and the energy produced may either be used in another
process or removed as waste heat to the environment. The condensed
refrigerant may be distributed to a location (space or industrial
process) which needs cooling and the refrigerant is evaporated at a
pressure corresponding to an evaporating temperature of
6-20.degree. C. which provides the cooling of the environment,
industrial process, or space. Alternatively, indirect cooling may
be used in which the liquid refrigerent is evaporated outside the
building cooling a second liquid to be transported to the building
for delivering to coolness. The evaporated refrigerant is then
absorbed into the concentrated working solution and returned to the
solar panel for reheating in the solar panel. The method of the
invention has the advantage of being simple and effective thereby
reducing loss of energy and temperature in the cooling system.
[0018] Preferred embodiments of the invention include that the heat
generated by the condensing and the absorbing step is removed by a
single fan. A volume corresponding to or larger than the volume in
the solar panels of the first step a) in the process description
above may be integrated into the volume of the absorber acting as a
reservoir as the volume of the absorber is sufficiently large to
contain the content of working fluid in panels, pipes, heat
exchangers. The volume of working fluid in the solar panel may be
drained to the reservoir of the absorber during inoperability of
the system. The solar panel may be arranged in a position above the
reservoir of the absorber to allow gravity to transfer the working
fluid to the reservoir of the absorber. The concentrated working
solution in the absorber may be distributed by a liquid distributor
through one or more tubes to the absorber tubes where a
liquid/vapor counter flow allows for absorption of vapor into the
working fluid. The internal area of the absorber tubes may be
enhanced by grooves in the absorber tube inner wall or by inserts
in the absorber tubes for a further inner surface area enhancement.
The inserts may be a single plate strip, a cross inserts or other
shapes fitted into the tube. The working fluid will not fill the
absorber tube completely and a liquid film is ideally formed on the
inner surfaces of the absorber tubes. The fan may be positioned to
deliver an air current to the one or more tube(s) to obtain a
cooling. The absorber liquid distributor may have internal elements
for distributing of a liquid film to the absorber tubes. The liquid
distributor may be constructed such that the flow of liquid is
distributed by a tube with one or more exits for optimal liquid
flow over a distance. The exits may be pointing upwards, side wards
or downwards. A refrigerant vapor distributor may be integrated
with the reservoir of the absorber. The liquid volume of the
condenser may be drained to the evaporator. The working solution
may be a solution of lithium bromide, ammonia or other salts in
water, lithium bromide being presently preferred. The amount of
lithium bromide may be 45 to 65% by weight. The absolute pressure
of the system may be 8 to 120 mbar for lithium bromide and similar
aqueous solutions. The temperature of the working solution in the
upper part of the solar panel may be 60-95.degree. C., suitably
70-90.degree. C. The temperature of the vapor produced by the
evaporation of liquid refrigerant may be 6-20.degree. C., such as
8-16.degree. C., suitably 10-14.degree. C., and optimally around
12.degree. C. The evaporation may be performed using forced or
natural convection around the evaporator. The solar panel is
primarily powered by solar radiation but may optionally be assisted
with a different heating source. The heating source may be powered
directly or indirectly with conventional fossil fuels, renewables
such as biomass, district heating or recovered waste heat or other
combustibles.
[0019] The invention also relates to a building chilling system,
using solar thermal energy, comprising [0020] A solar thermal panel
containing an working solution to be heated by solar radiation,
thereby separating the working solution in a vapor and a
concentrated working solution, [0021] A condenser for condensing
the vapor to liquid refrigerant, [0022] Pressure reducing means
capable of decreasing the evaporation pressure to a pressure
corresponding to an evaporation temperature of 6-20.degree. C.,
[0023] An evaporator positioned [0024] i. in a building to be
chilled, [0025] ii. or outside a building to be chilled, wherein
the cooling obtained by evaporation is transferred to a cooling
liquid outside the building and transported to the building to be
chilled for delivery of the cooling, and [0026] An absorber for
absorbing the vapor from the evaporator in the concentrated working
solution.
[0027] Preferred embodiments of the invention include that the
condenser and the absorber are arranged in a common entity, which
may be cooled by a single fan. The condenser and the absorber in
the common entity may be positioned adjacent in parallel for the
use of a single fan or the condenser and the absorber in the common
entity may be positioned adjacent in series for the use of a single
fan. A funnel may be installed between the fan and the common
entity to concentrate the air current.
[0028] The chilling system of the invention may comprise a
liquid-liquid heat recovery heat exchanger arranged in the system
for cooling the concentrated working solution from the solar panel,
whereas the working solution from the absorber towards the panels
is heated.
[0029] The absorber may contain a reservoir having a volume capable
of containing the amount of working fluid in the solar panel as
well as pipes.
[0030] The solar panel may be arranged at a position higher than
the reservoir of the absorber to allow for drainage by gravity from
the solar panel to the reservoir of the absorber. The absorber may
comprise a liquid distributor for the concentrated working solution
and a vapor distributor connected by one or more tubes arranged to
allow for the concentrated working solution to flow from the liquid
distributor through the tube(s) by gravity towards the vapor
distributor in counter-flow with the vapor. The one or more tubes
may be essentially vertical and the fan may be arranged so that the
air current is directed towards the one or more tubes for allowing
a cooling to take place. The one or more absorber tubes may be
having inserts for enhancement of internal absorption area. The
liquid distributor may have a tube with exit(s) facing upwards,
sidewards or downwards for flow distribution over a length of
internal elements for distributing the liquid in an optimal way.
The reservoir of the absorber may be integrated with the vapor
distributor.
[0031] The evaporator may be connected to the pressure reducing
means and/or the absorber with pipework of a polymeric material.
Further pipework and also components in the system where a
diffusion impervious material is required or advantageous may be
prepared of a polymeric material. The polymeric material may be
cross-linked polyethylene (PEX). The condenser may be positioned at
a height above the height of the evaporator to allow for the
condenser to be drainable by gravity. A hermetic pump may be used
for returning the working solution from the absorber to the solar
panel. A hermetic pump does not contain a shaft sealing. The
pressure reducing means may be a throttle valve, solenoid valve,
capillary tube or orifice.
[0032] One of the main barriers for commercial breakthrough of
solar cooling is the production cost of the solar chiller system.
The present invention offers an option for lowering the cost. In
addition the weight and footprint of the solar chiller is
reduced.
[0033] The chiller system and the method of the invention may
optionally comprise one or more of the following characteristics:
[0034] A. Reducing fan power for coolers [0035] B. Working fluid in
solar panels [0036] C. Drain-back functionality of panels with
working fluid [0037] D. Integration of drain-back storage with
absorber unit [0038] E. Option for evaporating of refrigerant in
indoor chiller module [0039] F. Alternative materials in
construction of solar coolers [0040] G. Condenser for refrigerant
is drainable by gravity [0041] H. Use of hermetic pump [0042] I.
Use of inserts in the absorber tubes
[0043] Ad. A. The power consumption of auxiliary equipment such as
fans is parasitic in relation to the chiller operation and are as
such decreasing the electrical COP (Coefficient Of Performance) of
the system. It is therefore desirable to reduce the system
electrical power consumption for an efficient chiller operation.
The power consumption of a fan is related to the flow rate of the
air being transported and to parasitic fan losses. Reducing the
latter increases the chiller electrical COP. Furthermore each fan
reflects an increase in system component count and hence system
cost. In an aspect of the invention it relates to a reduction of
the number of dry cooler fans for the condenser and absorber by an
appropriate arrangement of said heat exchangers. The embodiment of
the invention comprises an arrangement of the condenser and
absorber adjacent in either parallel or in series, which allows for
using a single fan for cooling of both units instead of separate
fans for each. This embodiment furthermore reduces the energy loss
associated with fans and allows for reducing the footprint due to a
condensed arrangement.
[0044] Ad. B. Conventionally, the solar thermal energy received by
the solar panels is transferred to the solar chiller system by a
liquid heat exchanger by which the solar thermal panel volume is
separated from the chiller volume. The use of a heat exchanger
causes a temperature loss and use of additional components such as
heat exchanger and a circulation pump. In an embodiment of the
invention it relates to a reduction of the number of units required
for transferring solar thermal energy into the system as well as
removing the undesired temperature loss. The embodiment of the
invention comprises an integration of the solar thermal panel
volume into the system volume by having the working fluid led
directly into the panel, thereby transferring solar thermal energy
directly to the solution in the solar panel. This allows for a
removal of the liquid heat exchanger and the associated temperature
loss and hence a decreased material consumption and associated
component cost.
[0045] Ad. C. The solar thermal panels are positioned outside and
are subjected to the ambient conditions. That means that during
sunshine and inoperability of the system, the energy transfer to
the panels require energy to be removed from the panels to avoid
overheating of the panels. This situation can lead to damage and
increased downtime of the system. The invention relates in a
certain aspect to the use of drain-back of the working solution
from the solar thermal panels, thereby removing the fluid when the
attached solar unit is not in operation. The invention comprises
the system design to allow for a drain-back by gravity from the
solar thermal panels to avoid overheating during warm seasons
during system shut-down as well as protection of the panels during
cold periods where the system is not in operation. This design
feature allows for omitting the antifreeze agents or other
additives, which reduces the component count and hence reduces
material consumption.
[0046] Ad. D. The working solution of the solar panel, especially
when the solar thermal panel is integrated into the system volume,
may drain back to one or more reservoirs. The reservoir(s) can be
of temporarily use solely or the reservoir may have an operational
functionality. The invention relates in an aspect to an efficient
design of the absorber as a part of the drain-back system. The
absorber comprises in this embodiment a liquid distributor attached
to tubes, in which the absorption process takes place, with a
liquid reservoir at the lowest point of the absorber. The liquid
reservoir acts also as a gas distributor for the vapor entering the
absorber from the evaporator. This allows for the absorber to
function with multiple functionalities, hence reducing the amount
of dedicated components and reducing the material consumption.
[0047] Ad. E. Conventionally, the solar chiller cooling unit
positioned in the air conditioned space is a separate circuit that
interacts with the solar chiller system via a heat exchanger. The
separate circuit has a circulation pump attached for the transport
of cooling media. In an aspect of the present invention it relates
to the reduction of heat exchanger numbers, auxiliary equipment in
the design of the evaporator, and of a cooling circuit that
circulates cooling fluid to the air conditioned room. In an aspect
of the invention it comprises a direct evaporation unit integrated
into the system volume positioned in the room. This allows for the
saving of the cooling circuit heat exchanger, attached circulation
pump, and expansion vessel. The invention furthermore reduces the
temperature loss associated with a heat exchanger.
[0048] Ad. F. The materials used in solar chillers are typically
stainless steel type metals, copper, brass, and similar alloys.
These metals are high priced materials and therefore the world
metal market pricing is highly influential on the cost of a solar
chiller, and the chiller cost is hence sensitive to the metal
pricing trends. The invention relates to alternative material
choice for components used in solar chillers. The alternative
materials can be plastic or composite materials for reservoir,
valves, and heat exchanger pipework and casings. According to the
present invention it is suggested in an embodiment to use polymeric
materials with or without diffusion barrier as a substitute of
metal piping or other system parts. This allows for a reduced
sensitivity towards the metal pricing trend and reduced corrosion
issues associated with metals. It also reduces the material
consumption for welding and soldering of tubes and components
during assembly and installation.
[0049] Ad. G. The efficiency and performance of the solar chiller
depends on system pressure leaks and pressure losses through the
individual components. Change in pressure due to non-process
related pressure loss will increase evaporation temperature and
thus reduce the COP. The invention relates to a condenser design
that allows for the condenser to be drainable by gravity whereby
the gravity assists in reducing the required pressure for transport
of liquid from the condenser unit. The natural gravity driven flow
of the condensed liquid is hence assisting in maintaining a high
system COP which also ensures low material consumption. The
drainable design of components protects the system components
during the cold seasons.
[0050] Ad. H. The solar chillers that operate under vacuum, such as
the subject for this invention, are sensitive to any leakage that
imposes an increase of the absolute pressure in the chiller system.
Any pressure increase is reflected as a decrease of chiller COP.
The chiller vacuum system is hence desirably tight and any objects
reaching from vacuum volume to surroundings are undesirable. An
undesired pressure increase of the chiller system is subject to
service or maintenance of the chiller. In an aspect, the invention
relates to a reduction of the system leak rate by the use of a
hermetic pump for the solution circulation. By avoiding shaft
sealings, the leak rate is reduced, hence the chiller COP is not
severely affected and the frequency between chiller services is
potentially reduced.
[0051] Ad. I. The flow of solution liquid is ideally a liquid film
on the absorber tubes inner walls. A high liquid area aids the mass
absorption and in some cases extra absorber tubes have been used
for ensuring only sufficient absorption area. To enhance the inner
wall area of the absorber for mass absorption, inserts in the
absorber tubes can be used. The inserts can be straight plates,
bend plates, cross plates, star shaped plates or other geometries.
Grooved tubes are an alternative. The inserts are ideally touching
the tube wall, but need not and the inserts can be fixed in
position by choice.
BRIEF DISCLOSURE OF THE FIGURES
[0052] FIG. 1 shows an overview of the complete absorption cooling
system including solar thermal panels,
[0053] FIG. 2 shows an arrangement of the condenser and the
absorber with a single fan,
[0054] FIG. 3 shows an arrangement of the condenser and the
absorber with a single fan and a funnel,
[0055] FIG. 4 shows an absorber with liquid distributor, absorber
tubes and reservoir, and
[0056] FIG. 5 shows a schematic evaporator to be positioned
in-house.
[0057] FIG. 6 shows a schematic of the absorber tube inserts.
DETAILED DISCLOSURE OF THE INVENTION
[0058] FIG. 1: The figure shows a schematic display of a single
effect absorption solar chiller cycle. The solar chiller is powered
with solar thermal energy (1) or other sources of heat source and
produces cold liquid refrigerant for air conditioning. The
evaporator (5) shown as a unit with separated tubes can be located
near to the solar thermal panels (1) or at a distance as
appropriate. The system can be located underneath or adjacent to
the solar thermal panels.
[0059] The solution may be added corrosion inhibitors, mass
transfer accelerators, or other chemical substances for improving
the performance and lifetime of the equipment or for reducing the
need for maintenance. In cases where the working fluid consists of
lithium bromide and water, the concentration of the solution may be
in the range of 45 to 65%, preferably 50 to 63% and optimally 54 to
60% mass of Libr. The system operates under vacuum at an absolute
pressure corresponding to an evaporation temperature of
6-20.degree. C.
[0060] The energy supply to the system is provided primarily by
solar radiation (thermal) through the solar panel which is an
integrated part of the system. The temperature of the fluid in top
of the solar panel is approx. 75-90.degree. C. but may vary to
60-110.degree. C. depending on operating and ambient conditions.
The panels are preferably integrated into the chiller volume
allowing for the solution to flow into the panels. Alternatively a
separate flow circuit for the panels connected to the chiller
volume by a heat exchanger can be used. The solar panel (1) may be
assisted with a back-up heat source. The heat source may be powered
directly or indirectly with fuels, renewables such as biomass,
district heating or recovered waste heat from various sources where
available.
[0061] The concentrated working solution is directed into a
liquid-liquid heat recovery heat exchanger (2) for the improvement
of the cycle COP and to decrease the temperature of the solution in
preparation for downstream process, producing low temperature
concentrated working solution. The pressure of the concentrated
working solution is adjusted to that from the evaporator by means
of a pressure reduction device (3).
[0062] The produced vapor is condensed by removing energy, thereby
producing liquid refrigerant. The condensing process is ideally
performed at constant pressure but a deviation in pressure over the
condenser (8) corresponding to a temperature shift of up to 20%
through the condenser in degree Celsius is acceptable.
[0063] The absolute pressure of the condensed refrigerant is
decreased to a target pressure corresponding to the desired
evaporation temperature. The pressure reduction is provided by
means of a pressure reduction device (4). The pressure reduction
device may be a valve (4), capillary tube, orifice or other means
allowing the reduction of pressure to target the required
evaporation temperature.
[0064] In the evaporator (5) the liquid refrigerant is evaporated
by adding energy at ideally constant pressure. The evaporation
temperature is in the range of 5-20.degree. C., preferably
8-16.degree. optimally 10-14.degree. C. and preferably at
12.degree. C. The evaporation pressure in the evaporator is fully
determined by the evaporation temperature. The process creates cool
refrigerant vapor and the evaporation energy is used for cooling
either as a direct evaporation in an in-house positioned unit or as
an indirect liquid cooling circuit with the evaporator positioned
separate from the cooled location or process.
[0065] In the absorber (7) the concentrated working solution and
the vapor from the evaporator is combined in an exothermic
absorption process producing a weaker working solution. The
absorption process is normally cooled. The cooling is performed
using ambient air driven by a fan (9) or by cooling the component
with cooling liquid or heat recovery device. The weaker working
solution is increased in pressure, producing a solution at elevated
pressure, using a circulation pump (6).
[0066] The weak working solution is directed to liquid-liquid heat
exchanger (2) for the exchange of energy with the concentrated high
temperature working solution for the improvement of cycle COP by
increasing the weak solution temperature. A weaker high temperature
working solution is produced. The weak high temperature working
solution is transferred to the solar panels or to a alternative
energy supply in case the panels do not provide heat input (e.g. at
no operation at night or the absence of solar panels). The closed
cycle has returned to the point of beginning.
[0067] FIG. 2: The condenser and absorber (22) are positioned
adjacent, either in parallel or series and supplied with air by a
fan (21). By arrangement in series, one unit will be positioned
upstream of the other which will increase the cooling temperature
for the downstream unit. Preferably the absorber is cooled by the
fresh non-heated ambient air, but either unit may be cooled with
the fresh non-heated ambient air. By arranging the heat exchangers
in parallel, each heat exchanger will be cooled with the same air
temperature. The fan is powered by electricity and provides air for
cooling of the condenser and the absorber.
[0068] FIG. 3: To increase pressure fan (31) efficiency for
arrangement in parallel, a funnel (32) may be installed between the
condenser/absorber and the fans. The funnel assists in guiding the
cooling air to increase flow distribution and/or to avoid false air
intake. The funnel can be of any converging shape. Preferably the
funnel is aerodynamically shaped for low pressure loss.
[0069] FIG. 4: The absorber may be a multipurpose component. The
top of the absorber is a liquid distributor (41) to which the
concentrated working solution is directed. The liquid distributor
distributes the working solution to the absorber tubes (44) in
which the solution flows internally. These tubes act as a heat
exchanger. The liquid distributor may or may not have a liquid
level above the tubes. The inner of the tubes act also as an
absorber in which vapor is absorbed into the working solution. The
absorber tubes are vertical and the design is self-draining, but
deviation from vertical to up to 88.degree. in all directions is
acceptable. The process is an exothermic process requiring cooling.
At the bottom of the absorber, the solution enters a liquid
reservoir (43). The liquid reservoir acts as a reservoir for the
solution during operation, as drain-back reservoir when the unit is
not in operation and as vapor distributor for the vapor from the
evaporator. The drain-back reservoir is important for the
collection and storage of the working solution e.g. when the solar
chiller is shut down. The solution preferably drains back from the
solar panel due to gravity and is collected in some of the lower
positioned volumes of the absorber. The reservoir may or may not
have a working solution level stored during operation as the
solution may flow directly to the pump. The absorber reservoir is
suitably designed to allow the collected working solution to flow
by gravity towards the pump. The absorber reservoir, position, or
technical means should ensure that solution does not flow into the
evaporator for contamination reasons.
[0070] FIG. 5: The evaporator (51) is for directly or indirectly
evaporation of refrigerant. For directly evaporation the evaporator
is positioned in the space that requires cooling. The evaporator
may then be connected to a fan (52) for forced convection or
operate without a fan for natural convection.
[0071] For indirectly cooling, the evaporator cools another media
such as chilled liquid (may be water) (53) in a configuration that
allows for superheating of the vapor and the evaporator may be
positioned in proximity to the solar panels, absorber and
particular preferably is below the condenser to allow refrigerant
to flow to the evaporator without a circulation pump.
[0072] FIG. 6: The internal area of the absorber tube(s) (61) where
the absorption of vapor into a liquid film occurs can be enhanced
by adding inserts in the tube(s). The number of inserts in one tube
may be one, but are not restricted to that. The inserts can have
any form and shape, preferably a prolonged shape that allow for the
insert to reach from tube entrance to tube exit. In the lower part
of the figure cross-sections of 3 different tubes with insert are
shown. The insert form can be a cross (62), single straight slap
(63), a bend slap (64), or any other shape that will fit into the
tube.
* * * * *