U.S. patent application number 13/148981 was filed with the patent office on 2012-02-16 for fluid conditioning arrangements.
Invention is credited to Daniel Becerra, Mathew Holloway, William Linsey Penfold, Karina Torlei.
Application Number | 20120037342 13/148981 |
Document ID | / |
Family ID | 45569788 |
Filed Date | 2012-02-16 |
United States Patent
Application |
20120037342 |
Kind Code |
A1 |
Holloway; Mathew ; et
al. |
February 16, 2012 |
FLUID CONDITIONING ARRANGEMENTS
Abstract
A fluid conditioning arrangement comprises a primary heat
exchanger configured to cool and/or heat the fluid; a secondary
heat exchanger configured to cool and/or heat the fluid; and a
controller for operating said secondary heat exchanger when said
primary heat exchanger fails to cool and/or heat the fluid at a
predetermined acceptablelevel; wherein said primary heat exchanger
is a phase change material (PCM) based heat exchanger.
Inventors: |
Holloway; Mathew; (Emsowrth,
GB) ; Torlei; Karina; (London, GB) ; Becerra;
Daniel; (London, GB) ; Penfold; William Linsey;
(Southampton, GB) |
Family ID: |
45569788 |
Appl. No.: |
13/148981 |
Filed: |
February 11, 2010 |
PCT Filed: |
February 11, 2010 |
PCT NO: |
PCT/GB2010/050221 |
371 Date: |
October 31, 2011 |
Current U.S.
Class: |
165/104.13 ;
165/104.21 |
Current CPC
Class: |
Y02E 60/147 20130101;
F24F 5/0021 20130101; Y02E 60/145 20130101; F28F 3/027 20130101;
F28D 20/021 20130101; Y02E 60/14 20130101; F24F 12/003
20130101 |
Class at
Publication: |
165/104.13 ;
165/104.21 |
International
Class: |
F28D 15/02 20060101
F28D015/02; F28D 15/00 20060101 F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 11, 2009 |
GB |
PCT GB2009 000377 |
Aug 11, 2009 |
GB |
0914030.2 |
Sep 16, 2009 |
GB |
0916217.3 |
Claims
1. A fluid conditioning arrangement comprising a primary heat
exchanger configured to cool and/or heat the fluid; a secondary
heat exchanger configured to cool and/or heat the fluid; and a
controller for operating said secondary heat exchanger when said
primary heat exchanger fails to cool and/or heat the fluid at a
predetermined acceptable level; wherein said primary heat exchanger
is a phase change material (PCM) based heat exchanger.
2. An arrangement according to claim 1, wherein said secondary heat
exchanger is selected from: a vapour compression cycle based air
conditioning system, a heat pump, an absorption chiller, a
desiccant, an adsorption cooler or a heater element.
3. An arrangement according to claim 1, wherein said secondary heat
exchanger incorporates a liquid store suitable for cryogenic
cooling.
4. An arrangement according to claim 1, wherein said secondary heat
exchanger incorporates an evaporative cooler.
5. An arrangement according to claim 4, wherein said evaporative
cooler incorporates a housing with an air intake; a corresponding
air outlet; a liquid inlet; a corresponding liquid outlet; and a
wicking surface.
6. An arrangement according to claim 1, wherein said secondary heat
exchanger incorporates a Peltier cooler.
7. An arrangement according to claim 1, wherein said secondary heat
exchanger exchanges heat with a liquid which then exchanges heat
with the PCM of said primary heat exchanger.
8. An arrangement according to claim 1, wherein said primary heat
exchanger incorporates one or more units housing PCM; wherein said
housing incorporates a PCM tank.
9. An arrangement according to claim 8, wherein said tank
incorporates insulated sides and at least one side without
insulation in order to enhance convection through said side.
10. A phase change material (PCM) module comprising a number of PCM
packs; a housing for thermally insulating said number of PCM packs
from a module's surrounding medium; said packs being in the form of
a panel with an upper surface, a lower surface, and relatively
narrow lateral sides; wherein a plurality of troughs in at least
either the upper or lower surfaces of the panel are provided to
allow fluid to flow through the module for heat exchange with the
PCM.
11. A phase change material (PCM) module comprising a number of PCM
monoliths; a housing for thermally insulating said number of PCM
monoliths from a module's surrounding medium; and gaps being formed
between a stack of said monoliths in said module to allow fluid to
flow through the module for heat exchange with the PCM.
12. A module according to claim 11, wherein said monoliths are
hexagonal in cross-section.
13. A phase change material (PCM) module comprising a number of PCM
packs; a housing for thermally insulating said number of PCM packs
from a module's surrounding medium; and conduits passing through
said PCM packs to allow fluid to flow through the module for heat
exchange with the PCM.
14. A fluid conditioning arrangement comprising a first heat
exchanger configured to cool and/or heat fluid; and a second heat
exchanger configured to cool and/or heat fluid; wherein said one of
said heat exchangers is a phase change material (PCM) based heat
exchanger; and the other is an evaporative cooler.
15. A fluid conditioning arrangement comprising a first heat
exchanger configured to cool and/or heat fluid; and a second heat
exchanger configured to cool and/or heat fluid; wherein said one of
said heat exchangers is a phase change material (PCM) based heat
exchanger; and the other is a Peltier cooler.
16. A fluid conditioning arrangement comprising a first heat
exchanger configured to cool and/or heat fluid; and a second heat
exchanger configured to cool and/or heat fluid; wherein said one of
said heat exchangers is a phase change material (PCM) based heat
exchanger; and the other is a solar based heat exchanger.
17. (canceled)
Description
FIELD OF THE INVENTION
[0001] The invention relates to fluid conditioning arrangements,
phase change material (PCM) modules and/or components operated in
conjunction with these. The invention is of particular
applicability to the use of PCM for the ambient temperature
control, for example within domestic and commercial buildings.
BACKGROUND
[0002] Phase change materials use the latent heat property of
material to store thermal energy and can be used in methods of
controlling temperature. Phase change materials are either organic
such as paraffin or non-paraffin compounds, inorganic (salt
hydrates and metallics) or eutectic (organic-organic,
organic-inorganic, inorganic-inorganic). Typically, PCMs have a
latent heat capacity at least ten times larger than their specific
heat capacity.
[0003] The following prior art documents are acknowledged:
DE102007013779, U.S. Pat. No. 5,647,225, U.S. Pat. No. 7,124,594,
U.S. Pat. No. 7,162,878, U.S. Pat. No. 5,255,526, U.S. Pat. No.
7,363,772, U.S. Pat. No. 5,211,029, U.S. Pat. No. 4,916,916, U.S.
Pat. No 5,647,225, U.S. Pat. No. 5,860,287, and U.S. Pat. No.
6,393,861.
[0004] One of the objects of the invention is to try to improve
primarily PCM based fluid conditioning arrangements in terms of
performance and reliability.
BRIEF SUMMARY OF THE DISCLOSURE
[0005] In a first broad independent aspect, the invention provides
a fluid conditioning arrangement comprising a primary heat
exchanger configured to cool and/or heat fluid; a secondary heat
exchanger configured to cool and/or heat fluid; and a controller
for operating said secondary heat exchanger when said primary heat
exchanger fails to cool and/or heat the fluid at a predetermined
acceptable level, (or the fluid fails to cool or heat the primary
heat exchanger to an acceptable level), wherein said primary heat
exchanger is a phase change material (PCM) based heat
exchanger.
[0006] This configuration improves the overall performance of the
system as it allows the PCM heat exchanger to do most of the work
of cooling and/or heating for minimal energy usage, but provides a
backup system to improve performance and reliability when needed.
For example, a PCM may be selected which freezes/melts around room
temperature (20-26 C). In many climates such as Northern Europe the
night time temperatures fall below 20 C, even in summer. Therefore
the PCM can be used to store cool energy from the night to provide
space cooling during the day. Because these cycles rely on natural
fluctuations and the weather, on occasion the night time
temperatures may not be low enough to freeze or recharge the PCM.
In this situation, a back up or booster system can be used to
provide additional cooling during the night, because the
temperature is already lower at night the back up or booster system
has to do less work than if it was run during the day and has the
advantage of using cheaper night time electricity. In this
situation the backup booster may only need to cool the night time
air by the difference between the target temperature and the actual
night time temperature, for example if the temperature needed to
freeze the PCM is 18 C, and the night time temperature is 20 C the
booster only needs to provide an additional 2 degrees of
cooling.
[0007] In a second scenario the PCM based heat exchanger may be
required to provide cooling or heating. Because the latent heat
store is finite there may be occasions where the system is required
to provide more energy than stored. If the primary heat exchanger
cannot adequately heat or cool the fluid then the secondary system
can provide an additional heating or cooling of the fluid. This
allows a primarily PCM cooling and/or heating system to minimise
energy usage and operate under normal conditions, but have the
performance and reliability of a conventional system by
incorporating a booster or backup system. It allows the arrangement
to operate over a wide variety of outside temperature conditions.
It also further improves the energy efficiency when compared to
conventional systems.
[0008] In a subsidiary aspect, said secondary heat exchanger is
selected from: a vapour compression cycle based air conditioning
system, a heat pump, an absorption chiller, a desiccant, an
adsorption cooler or a heater element, for example an electrical
heater element, an electrical panel heater, or infrared heater.
[0009] In a subsidiary aspect, the secondary heat exchanger
incorporates a liquid store suitable for cryogenic cooling. This
combination further reduces the energy requirements for the
secondary heat exchanger. It is particularly advantageous when the
use of the secondary heat exchanger is relatively infrequent.
[0010] In a further subsidiary aspect, said secondary heat
exchanger incorporates a single or multiple stage evaporative
cooler. This combination synergistically reduces the energy
requirement for an achievable level of cooling, because an
evaporative cooler can be more effective at night.
[0011] In a further subsidiary aspect, the evaporative cooler
incorporates a housing with an air intake; a corresponding air
outlet; a liquid inlet; a corresponding liquid outlet; and a
wicking surface. It can also improve the heat exchange between an
evaporative cooler and a PCM heat exchanger due to the benefits of
a fluid based heat exchanger when compared to an air based heat
exchanger.
[0012] In a further subsidiary aspect, said secondary heat
exchanger incorporates a Peltier cooler. This configuration is also
particularly advantageous in that the secondary heat exchanger is
only required infrequently. It also lends itself to a particularly
compact solution. In a further subsidiary aspect, said secondary
heat exchanger exchanges heat with a liquid which then exchanges
heat with the PCM of said primary heat exchanger. This
configuration has the advantage of using a heat transfer fluid with
a higher capacity than air. This kind of system may however still
be used to provide fresh cooled air.
[0013] In a further subsidiary aspect, said primary heat exchanger
incorporates one or more units housing PCM; wherein said housing
incorporates a PCM tank. This configuration simplifies the
construction when compared to multiple packs in a housing.
[0014] In a further subsidiary aspect, said tank incorporates
insulated sides and at least one side without insulation in order
to enhance convection through said side. This configuration is
particularly advantageous in order to release cooling/heating into
a room. In a generalization of this aspect, the tank may comprise
at least one side that, in use, faces the space with which heat is
to be exchanged, e.g. the room to be heated or cooled, and this
side may be uninsulated. The sides which do not face the space with
which heat is to be exchanged may be insulated.
[0015] In a further broad independent aspect, the invention
provides a phase change material (PCM) module comprising one or
more PCM packs; a housing for thermally insulating said number of
PCM packs from a module's surrounding medium; said packs being in
the form of a panel with an upper surface, a lower surface and
relatively narrow lateral sides; wherein a plurality of troughs in
at least either the upper or lower surfaces of the panel are
provided to allow fluid to flow through the module for heat
exchange with PCM. This configuration reduces the number of
components required in order to provide the spaces in a stack of
PCM packs, and maximises surface area and the energy storage
density of the heat exchanger.
[0016] In a further broad independent aspect, the invention
provides a phase change material (PCM) module comprising a number
of PCM monoliths or tubes; a housing for thermally insulating said
number of PCM monoliths from a module's surrounding medium; and
gaps being formed between a stack of said monoliths or tubes in
said module to allow fluid to flow through the module for heat
exchange with the PCM. This configuration allows a stack of such
monoliths or tubes to achieve improved heat exchange with a heat
transfer fluid. It also provides a particularly robust stack which
is also particularly straightforward to assemble whilst employing
relatively lightweight individual components.
[0017] In a further subsidiary aspect, said monoliths are hexagonal
in cross-section. This allows the individual monoliths to be
stacked in a uniform manner.
[0018] In a further broad independent aspect, the invention
provides a phase change material (PCM) module comprising a number
of PCM packs; a housing for thermally insulating said number of PCM
packs from a module's surrounding medium; and conduits passing
through said PCM packs to allow fluid to flow through the module
for heat exchange with the PCM. This configuration further improves
the efficiency of the heat exchange for certain applications.
[0019] In a further broad independent aspect, the invention
provides a fluid conditioning arrangement comprising a first heat
exchanger configured to heat and/or cool fluid; and a second heat
exchanger configured to cool and/or heat fluid; wherein said one of
said heat exchangers is a phase change material (PCM) based heat
exchanger and the other is an evaporative cooler. This
configuration is also particularly advantageous in terms of energy
efficiency when compared to conventional heat pumps and
conventional combinations of heat pumps and evaporative
coolers.
[0020] In a further broad independent aspect, the invention
provides a fluid conditioning arrangement comprising a first heat
exchanger configured to cool and/or heat fluid; and a second heat
exchanger configured to cool and/or heat fluid; wherein said one of
said heat exchangers is a phase change material (PCM) based heat
exchanger; and the other is a Peltier cooler. This configuration is
also particularly advantageous in terms of efficiency when compared
to conventional combinations of heat pumps and PCM material. It
lends itself to the Peltier acting as a booster system which is
particularly advantageous when the demand for the use of the
Peltier cooler is relatively infrequent.
[0021] In a further broad independent aspect, the invention
provides a fluid conditioning arrangement comprising a first heat
exchanger configured to cool and/or heat fluid; and a second heat
exchanger configured to cool and/or heat fluid; wherein said one of
said heat exchangers is a phase change material (PCM) based heat
exchanger; and the other is a solar based heat exchanger or solar
collector.
[0022] In a further broad independent aspect, the invention
provides a transportable PCM (phase change material) module
comprising a number of PCM packs; a housing for thermally insulting
said number of PCM packs from a module's surrounding medium; spaces
separating said packs and forming one or more channels for the flow
of a fluid; said housing incorporating a fluid inlet and a fluid
outlet; whereby, in use, fluid flows through said channels from
said inlet to said outlet.
[0023] This configuration is particularly advantageous because it
allows systems to be built up from a number of modules for variable
energy requirement. It may also reverse conventional thinking when
it is configured without any driven or powered component in the
module. It may thus allow for retrofitting to existing air flow
systems. It also improves energy usage effectiveness.
[0024] In a subsidiary aspect, said inlet and/or said outlet
incorporates one or more flow regulating valves. If the module
consists of these components only it further reduces the number of
components necessary and allows for particularly compact modules
compared to module incorporating power components per module.
[0025] In a further subsidiary aspect, said PCM packs are arranged
substantially side by side. In this configuration, the cooling is
advantageous.
[0026] In a further subsidiary aspect, said PCM packs are separated
by one or more thermal conductors extending transversely and
forming said channels. This allows the PCM portion to be of greater
effective volume and therefore improves its effectiveness.
[0027] Further aspects improve one or more of the following: the
effectiveness of the PCM, the turbulence of the flow, the
compactness of the system relative to its effectiveness, its
overall packaging weight and its manufacturing requirements.
[0028] In a further subsidiary aspect, said thermal conductors take
the form of a corrugated sheet.
[0029] In a further subsidiary aspect, at least one of said PCM
pack incorporates a corrugated wall forming a channel for the flow
of fluid.
[0030] In a further subsidiary aspect, a number of projections are
provided in at least one of said channels.
[0031] In a further subsidiary aspect, at least one of said PCM
pack incorporates a wall from which projections project into said
channel.
[0032] In a further subsidiary aspect, the or each PCM pack
comprises a laminate of a first conducting panel and a second
conducting panel enclosing a portion formed primarily of PCM;
wherein said portion of PCM incorporates thermal conductors. In a
further subsidiary aspect, said thermal conductors extend in a
transverse direction from one or both of said conducting
panels.
[0033] In a further subsidiary aspect, said thermal conductors form
hexagonal cells when viewed in plan.
[0034] In a further subsidiary aspect, said laminate further
incorporates a corrugated thermally conductive panel.
[0035] In a further subsidiary aspect, said laminate incorporates a
third conductive panel and a fourth conductive panel enclosing a
second portion formed primarily of PCM; and a corrugated thermally
conductive panel located between said second and third conductive
panels.
[0036] In a further subsidiary aspect, said laminate incorporates a
plurality of projections on said panels.
[0037] In a further subsidiary aspect, said thermally conductive
panels are selected from the group comprising aluminium based
material, steel based material, and plastics material.
[0038] In a further subsidiary aspect, said PCM is selected from
the group comprising a salt, a salt based hydrate, a mixture of
salt, and/or salt based hydrate, and/or an organic material.
[0039] In a further subsidiary aspect, said salt based hydrate are
selected from the group comprising hydrated calcium chloride or
hydrated sodium sulphate.
[0040] In a further subsidiary aspect, said salt based hydrate
incorporates a thickening agent selected from the group comprising
Xanthan and/or Laponite.
[0041] In a further subsidiary aspect, said organic material is
paraffin based.
[0042] In a further subsidiary aspect, said thermal conductors
incorporate a conductive compound mixed into said PCM. In a further
subsidiary aspect, said thermal conductor is a carbon based
compound mixed into said PCM.
[0043] In a further subsidiary aspect, said carbon based compound
is carbon black.
[0044] In a further subsidiary aspect, said thermal conductors
incorporate wire wool or chemical carbon nanotubes.
[0045] In a further subsidiary aspect, said module further
incorporates a pettier cooler.
[0046] In a further subsidiary aspect, said module further
incorporates an evaporative cooler.
[0047] In a second broad independent aspect, the invention provides
an air conditioning arrangement, comprising: [0048] one or more
transportable PCM modules according to any of the preceding claims;
and [0049] at least one transportable control module incorporating
a housing with an inlet and an outlet; and a pump for causing, in
use, the flow of fluid from said inlet to said outlet; [0050]
wherein said arrangement incorporates a conduit for linking said
transportable control module to said transportable PCM modules.
[0051] In a subsidiary aspect, said control module incorporates a
first and a second inlet located on separate sides of said housing
and a valve configured to regulate the intake between said
inlets.
[0052] In a further subsidiary aspect, said control module
incorporates an internal conduit between said inlet and said
outlet; said internal conduit comprising two adjacent paths, one of
which incorporates a pump and a second of which incorporates a
non-return valve.
[0053] In a further subsidiary aspect, said arrangement further
comprises a transportable backup module incorporating one of a heat
pump, an inverter, a peltier cooler, or an evaporative cooler; and
further incorporating means for linking said backup module to said
PCM module.
[0054] In a third broad independent aspect, a PCM (phase change
material) pack comprises a laminate of a first conducting panel and
a second conducting panel enclosing a portion formed primarily of
PCM; wherein said portion of PCM incorporates thermal
conductors.
[0055] In a subsidiary aspect, said thermal conductors extend in a
transverse direction from one or both of said conducting
panels.
[0056] In a further subsidiary aspect, said thermal conductors form
hexagonal cells when viewed in plan.
[0057] In a further subsidiary aspect, said laminate further
incorporates a corrugated thermally conductive panel.
[0058] In a further subsidiary aspect, said laminate incorporates a
third conductive panel and a fourth conductive panel enclosing a
second portion formed primarily of PCM; and a corrugated thermally
conductive panel located between said second and third conductive
panels.
[0059] In a further subsidiary aspect, said laminate incorporates a
plurality of projections on said panels.
[0060] In a further subsidiary aspect, said thermally conductive
panels are selected from the group comprising aluminium based
material, steel based material, and plastics material.
[0061] In a further subsidiary aspect, said PCM is selected from
the group comprising a salt, a salt based hydrate, a mixture of
salt, and/or salt based hydrate, and/or an organic material.
[0062] In a further subsidiary aspect, said salt based hydrate are
selected from the group comprising hydrated calcium chloride or
hydrated sodium sulphate. In a further subsidiary aspect, said salt
based hydrate incorporates a thickening agent selected from the
group comprising Xanthan and/or Laponite.
[0063] In a further subsidiary aspect, said organic material is
paraffin based.
[0064] In a further subsidiary aspect, said thermal conductors
incorporate a conductive compound mixed into said PCM.
[0065] In a further subsidiary aspect, said thermal conductor is a
carbon based compound mixed into said PCM.
[0066] In a further subsidiary aspect, said carbon based compound
is carbon black.
[0067] In a further subsidiary aspect, said thermal conductors
incorporate wire wool or chemical carbon nanotubes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0068] Embodiments of the invention are further described
hereinafter with reference to the accompanying drawings, in
which:
[0069] FIG. 1 shows a fluid conditioning arrangement in schematic
cross-sectional view of an embodiment incorporating primarily a PCM
module and secondarily a heat exchanger unit.
[0070] FIG. 2 shows a schematic cross-sectional view of a PCM based
fluid conditioning arrangement with a cryogenic booster.
[0071] FIG. 3 shows a schematic of a fluid conditioning arrangement
where the heat transfer between a first fluid conditioning
arrangement and a second fluid conditioning arrangement is achieved
by using fluid instead of air.
[0072] FIG. 4 shows a schematic of the central unit in a fluid
conditioning arrangement in accordance with a further
embodiment.
[0073] FIG. 5 shows a fluid conditioning arrangement incorporating
an evaporative unit.
[0074] FIG. 6 shows a module which has no PCM material.
[0075] FIG. 7 shows a PCM tank.
[0076] FIG. 8 shows a PCM module with a fluid based heat
exchange.
[0077] FIG. 9 shows a further embodiment with a PCM module of the
kind shown in FIG. 8.
[0078] FIG. 10 shows a control unit.
[0079] FIG. 11 shows a PCM module.
[0080] FIG. 12 shows a system with a couple of modules.
[0081] FIG. 13 shows a Peltiere booster.
[0082] FIGS. 14 show PCM packs in a plurality of views.
[0083] FIGS. 15 show PCM monoliths in a plurality of views.
[0084] FIGS. 16 show a plurality of PCM packs with hexagonal
components throughout.
[0085] FIGS. 17 shows PCM packs in a plurality of views.
[0086] FIGS. 18 show PCM packs with semi-circular troughs in a
plurality of views.
[0087] FIG. 19 shows a heat exchanger in cross section with a
plurality of PCM packs separated by corrugated plates.
[0088] FIG. 20 shows an exploded view in a perspective of the
embodiment of FIG. 19.
[0089] FIG. 21 shows in perspective view the combination of a PCM
pack with a corrugated plate.
[0090] FIG. 22 shows in perspective view a portable PCM pack.
[0091] FIGS. 23A and B show a PCM pack incorporating a thermally
conductive corrugated plate.
[0092] FIG. 24 shows in perspective view the assembly of a PCM pack
with a corrugated plate with a plurality of holes.
[0093] FIG. 25 shows a perspective view of the assembly of a
hexagonal array.
[0094] FIG. 26 shows a perspective view of the assembly of a PCM
pack with a hexagonal array with perforations.
[0095] FIGS. 27A and B show in cross section and in perspective
view PCM packs incorporating a corrugated wall.
[0096] FIGS. 28A and B show respectively in cross section and in
perspective a PCM pack whose envelope may be formed by
extrusion.
[0097] FIG. 29 shows a perspective view of a heat exchanger
incorporating a number of PCM packs of the kind shown in FIG.
28.
[0098] FIG. 30 shows a perspective view of a heat exchanger
incorporating a number of PCM packs of the embodiment of FIGS.
28.
[0099] FIG. 31 illustrates a phase change material pack in
accordance with the invention.
[0100] FIGS. 32 to 35 show schematically various embodiments of the
fluid conditioning system.
DETAILED DESCRIPTION
[0101] FIG. 1 shows a fluid conditioning arrangement generally
referenced 1. The air conditioning arrangement 1 incorporates three
air inlets respectively referenced 2, 3 and 4. Through inlet 3
fresh air from outside is drawn into the housing 5 by a fan or pump
6. It is important to note that whilst the embodiments of the
invention are primarily illustrated for cooling air, other fluids
may also be cooled and/or heated using these systems. In a
conventional mode of operation the air is fed through a PCM heat
exchanger 7 so that any heat in the air may be absorbed by the PCM
before exiting the housing through outlet 8. The arrangement may
preferably be equipped with a controller which may be configured to
measure the temperature of the PCM in order to determine the extent
of cooling that may be achieved by the heat exchanger. If due to
the conditions surrounding the heat exchanger, a booster is
required, as for example, the PCM heat exchanger fails to be
effective or the incoming fluid temperatures are not hot/cold
enough, the controller switches on the booster. In this
configuration, the booster incorporates a heat pump with a cold
heat exchanger and condensation tray 9 located in the path of the
air to be cooled and a hot heat exchanger 10. The heat pump would
incorporate the necessary compressor and expansion valve or an
absorption chiller, desiccant or adsorption cooler. Block 11
illustrates its location between hot heat exchanger 10 and cold
heat exchanger 9 when cooling. If the booster is provide to heat
the air then heat exchanger 10 is the cool heat exchanger and the
hot heat exchanger is heat exchanger 9. If the booster is needed
during the day, the controller would cause the provision of air
flow over the hot heat exchanger and would cause valve 12 to be
closed whilst valve 13 would be opened. An additional fan would
pump air through inlet 4 when the arrangement would be operating in
the booster mode of operation. Valve 14 is provided to allow
re-circulated air through the arrangement. Valve 15 is provided to
allow and/or block dependent upon the operator's selection of the
intake of fresh air to the arrangement. Valves 14 and 15 can be
combined. The invention also envisages systems without the valves
or with fewer valves dependent upon the level of control required.
Valve 16 is provided in the outlet to the room. The diagram does
not show other standard air conditioning components such as air
diffusers.
[0102] FIG. 2 shows a fluid conditioning arrangement generally
referenced 17 with a booster arrangement employing a liquid carbon
dioxide or nitrogen store to provide cooling as it expands in the
cold heat exchanger 18. Other than for this booster arrangement,
the fluid conditioning arrangement is similar to the arrangement
shown and described in detail in FIG. 1. Instead of incorporating
an air supply to the hot heat exchanger of the booster, the
arrangement incorporates an outlet 20 to allow air back outside. At
night, valve 15 opens and valve 14 closes to let in night air. The
controller of the arrangement causes the booster arrangement to
operate if the night air is not cold enough to freeze the PCM.
Valve 16 closes and valve 12 opens if the room temperature gets too
cold. During the day valve C closes and valve D opens to let air
into the room. If it is cold outside then valve 15 opens and valve
14 closes so less air is re-circulated and vice versa. An escape
valve is also provided to allow the expanded gas to escape once the
cooling has been transferred to the heat exchanger.
[0103] FIG. 3 shows a further fluid conditioning arrangement
generally referenced 21, with a central unit 22 incorporating a
booster unit 31, and a plurality of PCM units 23, 24 and 25
distributed around the space to be heated or cooled. Heat transfer
fluid lines are provided such as heat transfer fluid line 26. A
return line 27 is provided. When the control unit identifies that
the PCM stores which are positioned around the building have failed
to deliver the desired cooling effect, the booster system 31 is
switched on. The booster incorporates a heat exchanger, and could
be an evaporative, heat pump, vapour compression system, etc. An
air intake 29 draws air from outside across the heat exchanger 28
for cooling or heating when the booster is not needed. A valve 30
is provided between air inlet 29 and optional booster system 31. A
further air intake 32 allows air into the optional booster system
when in use. An air outlet 33 exhausts hot air from the booster if
applicable; for example if a heat pump is used to provide cooling.
The system can work in a number of ways, For example at night cool
air via inlet 29, can be passed over heat exchanger 28, and this
transferred to the PCM modules 23,24 and 25 via the separate fluid
lines 26 and 27 to freeze the PCM. If the night time temperature is
not cool enough to freeze the PCM then the booster 31 is turned on
and air is passed through booster 31 from outside and further
cooled by the booster before passing over heat exchanger 28. During
the day the PCM modules 23,24,25 can independently provide cooling
to the space as is needed, via radiation or by passing air over a
separate heat exchanger. If additional cooling or heating is needed
then the booster system can operate independently.
[0104] FIG. 4 shows a central unit for heating or cooling. This
system incorporates an external solar collector 34 which is in
fluid communication with a drain-off tank 35 which is configured to
prevent water freezing in the solar collector at night. A further
fluid line 36 is provided between tank 35 and a hot water tank 37.
A boiler 38 is located in series with the hot water tank. The solar
collector provides hot water or cooling by working as a radiator at
night. During the day, the solar collector provides hot water which
can be boosted by the boiler if needed and stored in the hot water
tank. Because much of the heat is provided during the day and
heating is required at night in residential buildings, the heat may
be stored in the latent heat stores around the building. In the
summer, the system can still store hot water in the tank for
showers but at night cooling from outside can be fed to the PCM
tanks in the room by bypassing the hot water tank.
[0105] Instead of employing the central unit of the kind described
in FIG. 4, an evaporative central unit generally referenced 39 may
be employed as shown in FIG. 5. This unit incorporates housing 40,
an air inlet 41 equipped with a filter, a single or a multiple
stage evaporative cooler with a wicking mesh 42, an exhaust air
outlet 43 and a fan 44 to cause the flow of air through the unit. A
first heat transfer line 45 is employed to return warm water to the
unit whilst a heat transfer line 46 is employed to allow cold water
to circulate to units in the room. This configuration is
particularly advantageous because it allows the working fluid, i.e.
the water from the evaporator to cool the PCM rather than the wet
air to be used by an evaporative cooler which increases the
humidity of a room.
[0106] Instead of, or in addition to, the PCM units of FIG. 3, a
unit 47 as shown in FIG. 6 may be employed. This unit may receive
and return fluid from a central system by heat transfer line inlet
48 and outlet 49. Housing 50 incorporates an air inlet 51 equipped
with a filter. An air outlet 52 is provided at an opposite side of
the housing 50. A fan 53 draws the air through the unit.
[0107] FIG. 7 shows an alternative unit which may be placed in a
building and which may receive and return fluid from a central
system. Unit 54 incorporates a housing 55 containing PCM 56. One or
more of the sides of the unit such as side 57 incorporates no
insulation so that cooling and/or heating may be released from
these sides by radiation and natural convection into the room.
[0108] FIG. 8 shows a unit 58 with a housing 59 for containing
spaced apart PCM components such as component 60. The unit
incorporates an air inlet 61 equipped with a filter and an air
outlet 62 with a fan 63. The PCM components may be plate-like,
spherical, shell-like and tubular heat exchangers etc. A heat
transfer line 64 forms a winding pattern in close proximity to the
PCM, or inside the PCM Pack itself in order to optimise heat
transfer. The invention also envisages employing two different
kinds of PCM with different melting temperatures for heating and
cooling. The heating range may be 40 to 60.degree. Degrees Celsius
whilst the cooling range may be 15 to 32.degree. Celsius.
[0109] FIG. 9 shows a further unit generally referenced 65 with a
housing 66 containing a plurality of PCM components such as
component 67. The housing 66 incorporates an air intake 68 and an
air outlet 69. A valve 70 is provided in a duct to regulate whether
air is received from outside or re-circulated from the room. A
further valve 71 is provided to regulate whether the air goes back
outside or whether it goes into the room. When this system is
combined with ventilation, it has the advantage of using a heat
transfer fluid line 72 with a higher heat capacity than air. It is
particularly advantageous when used to freeze PCM whilst still
providing fresh air.
[0110] FIG. 10 shows a control unit which may be used to assess the
requirements of a system. A valve 73 is provided to determine
whether the air is re-circulated from the building, taken from
outside, or taken from a booster. A fan 74 is provided to draw air
through the system. A pressure sensor 75 determines the pressure in
order to adjust the fan speed. If the pressure in the duct 76
increases, then the fan is caused to slow down. The pressure sensor
may incorporate a pilot tube or any other component suitable for
determining a value which may then be equated to the pressure in
the duct.
[0111] FIG. 11 shows a further unit generally referenced 77 with a
stack of PCM packs such as pack 78. Unit 77 incorporates a housing
79 for insulating the contents of the unit from the outside heat.
Dampers or valves 80 are provided in the inlet duct. A control unit
81 is provided to determine how much air flows through the unit
dependent upon how much cooling is needed. An operator interface
may be provided to adjust the level of cooling needed.
[0112] FIG. 12 shows two rooms 82 and 83, each incorporating a PCM
module respectively referenced 84 and 85. A duct 86 communicates
air to the PCM modules. A control unit which may be of the kind
shown in FIG. 10 is generally referenced 87. Upstream from the
control unit, a booster unit 88 is provided. The booster unit may
be of the kind shown in the previous embodiments. These control and
PCM modules can be those of FIGS. 10 and 11.
[0113] The booster may take the form of a Peltier booster which may
be of the form shown in FIG. 13 where a unit 89 has a hot side 90
and a cold side 91. The cold side 91 incorporates a condensation
tray 92 or a condensation catcher 93 in order to allow condensation
to run off.
[0114] FIG. 14 shows a PCM unit 94 incorporating PCM packs 95. Each
pack incorporates a plurality of recess portions 96 running the
length of the packs. The PCM packs incorporate PCM material and an
appropriate non-permeable envelope 97. The recesses are formed in
the envelope. The recesses extend only partially across the depth
of the packs. The recesses reduce in width progressively as the
depth of the recess increases. A flat base face 98 is provided at
the bottom of each recess. The recess portions allow the
circulation of fluid for optimum heat exchanging. FIG. 14B shows
the arrangement of Figure A in perspective view. FIG. 14 C shows a
cross-sectional view of a PCM pack, whilst FIG. 14D shows a
perspective view of a PCM pack.
[0115] FIGS. 15 show a PCM unit 99 with a plurality of hexagonal
tubes 100. Each tube contains PCM material and is capped at both
ends by a lid 101. By stacking a plurality of hexagonal tubes 100,
a number of hexagonal ducts 101 are formed which may be used to
allow heating fluid to circulate through the unit.
[0116] FIGS. 16 show views of PCM packs. PCM pack 102 with upper
and lower surfaces 103 and 104 which are formed by a succession of
recess portions such as recessed portion 105 which increases in
width from a flat base portion 106. The recess portions are
effectively half of a hexagon. There are provided protrusions 107
which are also effectively half of a hexagon. The PCM pack is
formed as if it were formed by a plurality of side-by-side
hexagonal tubes with the common faces such as face 108 removed so
that the PCM material is distributed throughout the PCM pack.
Thermal conductors may be provided between the upper surface 103
and the lower surface 104 in an alternative embodiment. By stacking
a plurality of PCM packs of this form as shown in FIG. 6F channels
for circulating fluid such as channel 109 are formed.
[0117] FIGS. 17 show PCM packs incorporating tubes at regular
intervals extending through the PCM layer. Tubes 110 may be used to
circulate cooling fluid as appropriate. A cap 111 allows access to
the inside of the pack for filling the pack with PCM. A second cap
112 is also provided for facilitating the filing and emptying of
the PCM pack.
[0118] FIGS. 18 show PCM packs in accordance with a further
embodiment where the pack 113 incorporates a plurality of
semi-circular, in cross section, troughs 114. The recesses or
troughs are provided in both the upper surface 115 and the lower
surface 116. The troughs in the upper surface are offset relative
to the troughs of the lower surface. A trough in the upper surface
is located opposite a flat outermost portion of the lower
surface.
[0119] FIG. 19 shows a PCM module in cross-section which takes the
form of a heat exchanger 242 with an insulative housing 243. The
housing wall may be selected to hold 80 to 90% of the "coolth" over
8 hours. It may be of approximately 25 mm in thickness with a
conductivity of 0.01 to 0.02 W/MK. On the inside of housing 243, a
conductive metal frame 244 forms a lining. A succession of layers
of corrugated plates such as plate 45 alternate with PCM pack
layers such as layer 246. FIG. 20 shows the components of FIG. 19
in an exploded view. The corrugated plate may instead be replaced
by a number of transverse fins or links which in a similar fashion
as the corrugated plate would increase the surface area in contact
with air flowing through the channels left between the PCM packs.
Since the surface area in contact with air is increased, the PCM
packs may be thicker thus allowing greater cooling to be achieved.
In a preferred embodiment, the gap between the PCM packs is
slightly smaller than the height of the corrugated fins to ensure
optimum thermal contact. In order to support the weight of the PCM
packs, there is provided rails on the inside of the frame (not
shown in the figures). FIG. 21 shows a corrugated plate 247 with a
number of projections such as projection 248. Alternatively, these
projections may be holes or a combination of holes and projections
in order to break up laminar flow by creating turbulence in order
to increase heat transfer. The corrugated plate 247 may be disposed
as shown in FIG. 19 adjacent to a sealed PCM pack 249. The
corrugated plate 247 may preferably be made of sheet metal
preferably less than 1 mm thick. For optimum structural strength
and thermal conductivity, a range of 0.1 to 0.2 mm is envisaged. A
number of known techniques are envisaged to form the plate such as
pressing or folding. Instead of employing sheet metal, a thermally
conductive plastics material may also be selected.
[0120] FIG. 22 shows a PCM pack 250 with an impermeable outer layer
251 for containing the PCM. A handle 252 is provided which may take
the form of an oblong opening. A number of recesses 253 and 254 are
provided on opposite lateral sides of the pack. These may be
employed in order to lock the pack into releasable attachment means
provided in a heat exchanger for example. This embodiment
illustrates how the PCM pack may be rendered readily portable.
[0121] FIG. 23A shows a PCM pack formed with an upper wall 255 and
a lower wall 256 for trapping PCM. Between walls 255 and 256, there
is provided a plate 257 formed as a succession of V-shaped portions
when viewed in cross-section. The components of FIG. 23A are shown
in FIG. 23B as glued or sealed together in order to prevent any
escape of PCM during use.
[0122] The PCM is one of an organic, a salt based hydrate, or a
combination of both. A paraffin based PCM is envisaged with a melt
temperature preferably within the range of 21 to 24 degrees
Celsius. In order to achieve an optimal melt temperature, the
different types of available paraffins are mixed in the appropriate
proportions.
[0123] Salt hydrates which are suitable for use may for example be
hydrated forms of calcium chloride or sodium sulphate. The
invention also envisages employing a thickening agent as an
addition to the salt hydrates to maintain the salt in its hydrated
form. Suitable thickening agents may be selected from the group
comprising: Xanthan or Laponite. In addition to the transverse
conductive fins of the corrugated plate 257 or instead of such
transverse fins, a conductive element may be suspended in the
mixture of PCM. An appropriate compound for suspension may be
carbon black.
[0124] FIG. 24 shows an alternative construction of a PCM pack
generally referenced 258. The configuration of the PCM pack differs
from the preceding embodiment in that a number of holes 259 are
provided in the fins 260 of the corrugated plate generally
referenced 261. Such holes allow molten PCM to distribute evenly
and to keep air out. The corrugated panel may be glued to improve
strength.
[0125] The corrugated panels may be pressed and mainly made of very
thin wall thicknesses such as less than 1 mm in order to keep
weight to a minimum whilst the profile/ridges/pattern adds a
strength. The transverse fins allow the thickness of the PCM pack
to be increased by improving conductivity. It allows the PCM to be
at an optimal maximum distance of between 4 to 16 mm (or 10 to 20
mm) from the links throughout the pack. Alternative thermal
conductors are envisaged to be located in the PCM such as wire
wool, chemical carbon nano-tubes, suspended carbon black which may
be randomly distributed throughout the material.
[0126] The transverse links may be made of thin metal/plastic which
would preferably be less than 1 mm in thickness. The shape and
configuration of the plate may be obtained by pressing, stamping
and/or folding processes.
[0127] FIG. 25 shows a PCM pack 262 in an exploded view with an
array of closely contiguous cylinders 263 for receiving PCM. The
cylindrical tubes may take the form of a hexagonal mesh. The array
may be formed from a single sheet which is laser cut and pulled
apart to result in an array with walls of a thickness of
approximately 0.1 mms. Secured to the top and bottom of the array,
there is provided top and bottom plates respectively referenced 264
and 265. The process of assembling may incorporate the following
steps: a) attaching the array of hexagonal receptacles to one of
the top or bottom plates, b) filling the tubes with PCM in its
molten phase allowing sufficient clearance for its expansion as it
freezes before c) gluing to attach the remaining panel.
[0128] An alternative PCM pack 266 is shown when compared to the
embodiment of FIG. 25. PCM pack 266 incorporates a shallow walled
plateau 267 into which an array of hexagonal receptacles 268 is
located. The array of receptacles is sealed between lid 269 and
plateau 267. Holes such as hole 270 are provided through each of
the hexagonal receptacles in order to allow PCM to distribute. The
panel 269 may be attached to the plateau 267 by ultrasonic welding
or by gluing.
[0129] If the PCM is selected to be salt based the material for the
pack is preferably selected to be a coated aluminium or a
conductive plastics material (for example K greater than 5 W/MK) or
stainless steel in order to prevent corrosion.
[0130] One of the key advantages of transverse links is that it
allows PCM packs to be made of a greater thickness than would
otherwise be possible. For example packs with material thicknesses
of 20 to 50 mm may be achieved with effective conductivity.
[0131] FIGS. 27A and 27B a PCM pack (FIG. 27A) and a stack of PCM
packs (FIG. 27B). In this embodiment, the PCM pack is generally
referenced 271 and is formed only of two plates 272 and 273
allowing for the filling of PCM in an array of cavities such as
cavity 274. The cavities are formed in cross-section in a V-shape.
The portions such as portion 275 would be exposed to air flow. In
addition, it is envisaged for the external surface exposed to the
flow to incorporate knurling and/or bumps. This kind of relief may
be used in any of the preceding embodiments in order to increase
the flow turbulence and therefore the heat transfer properties of
the pack. The undulated or corrugated plate 273 is formed for
example by pressing or folding. As indicated in the stack of packs
276 and 277 air may flow in the cavities provided as indicated by
the arrows. This embodiment allows an increase in surface area in
contact with the air and a reduction of the maximum distance
between the PCM and the conductive material. In other words, it
combines the function f the PCM packaging with the transverse links
inside as well as the corrugated heat exchanger in touch with the
air.
[0132] FIGS. 28A and 28B show a PCM pack 278 in two separate views.
The PCM packs 278 incorporate a single peripheral wall 279 with a
number of inwardly projecting webs such as web 280 and outwardly
projecting webs such as web 281. In other embodiments only
externally projecting webs may be provided and/or only internally
projecting webs. Within the envelope formed by peripheral wall 279,
PCM 282 is placed to fill the space. In order to enclose the PCM
pack, end pieces (not shown in the figures) may be provided and
secured onto lateral edges 283 and 284. The materials used for
these PCM packs may be a relatively low permeable plastics
material. Alternatively, coated aluminium is also advantageous.
Preferably, a conductive of plastics material would be selected
with a thermal conductivity factor greater than 1 W/MK. An option
of achieving this kind of conductive of plastics material for the
PCM pack material would be to add carbon nano-tubes or particles to
the plastics material. The process envisaged in order to produce
wall 279 would be to form the wall by extrusion.
[0133] FIG. 29 shows a PCM pack module generally referenced 285.
Module 285 incorporates an insulative outer layer 286 formed by
side walls 287, 288, a base wall 289 and a lid 290. Within the
insulation, there is provided a frame 291 with a number of ledges
such as ledge 292 for supporting a stack of PCM packs in a spaced
apart relationship. Gaps such as gap 93 are provided to allow the
circulation of fluid. The links 280 and 281 extend in this
embodiment only partially towards a neighbouring PCM pack
plate.
[0134] As shown in FIG. 30, during assembly, a side 294 may be
fully open in order to allow the insertion of the successive packs
in similar fashion to a drawer sliding into its case.
[0135] FIG. 31 shows a phase change material pack 300 according to
an embodiment of the invention. The pack is made from two pressed
panels 301 which are joined at their edges and at two locations 302
in the middle of the pack surface for strength. The surface of the
pack is textured to induce turbulent flow in the fluid (air)
passing over it.
[0136] A conductive PCM material allows the PCM packs to be
thicker, reducing manufacturing costs. Currently the PCM
packs/panels are 10-15 mm thick. Where salt based hydrates are used
then the pack material must be non-corrosive, non-permeable and
robust. Preferably, depending on the thickness, the material should
be thermally conductive.
[0137] Preferably metals are used to form the panels 301 as they
are non-permeable and highly conductive. Those with the best
corrosive properties are aluminium and stainless steel. Further
coatings may be needed to reduce the effects of corrosion depending
on the salt. Suitable techniques are anodizing, E-Coat or Electro
Coat, silane coating, PTFE. Depending on the method of manufacture
there are many processes which allow the protective layer to form
naturally during the manufacturing process. Aluminium alloys 5052
& 5251 have good formability and very good corrosion
resistance, reducing the need for the level of coatings.
[0138] Many plastics have poor permeability and their mechanical
properties degrade over time due to the effects of the salt hydrate
weakening the plastic, this means that plastics generally need
higher wall thickness, ie 1-5 mm rather than 0-1 mm with metals.
HDPE is one of the best off the shelf plastics. Additives/processes
used to make plastics more conductive also have a positive effect
on plastics permeability.
[0139] A composite material may be used. As used commonly in the
food industry this may consist of a film of a number of different
materials, e.g. aluminium foil for permeability reasons, plastic
for corrosive reasons.
[0140] The typical method of manufacture is using
superforming/hydroforming or stamping two sides of the pack, and
then epoxy gluing or welding the edges shut. A preferably
resealable opening is left to fill/refill the pack.
[0141] The methods to control the selective operation of the
secondary heat exchanger will now be described. Temperature sensors
are placed outside, or within a duct in which outside air enters
the building, and inside the area to be serviced by the system.
Depending on the required temperature inside the system can provide
ventilation, free cooling or cooling/heating via the latent heat
store. For example if it is colder outside than inside and cooling
is needed, the system can provide direct ventilation bypassing the
latent heat store to cool the room. This saves the latent heat
store until it is needed. If it is warmer outside than inside then
the proportion of outside air to re-circulated air is determined by
the minimal ventilation requirements, and the latent heat store is
used to cool the air.
[0142] The latent heat store is recharged by passing cool night
time air through the system, and either dumping the air in the room
(with the benefit of cooling the room) or outside (if the room is
occupied and in danger of being over cooled).
[0143] In winter the system traps excess heat at the end of the
day, or during peak heating periods (e.g. when the sun hits a glass
fronted building--even in winter overheating can occur in these
situations) and this is used to temper the ventilated air.
[0144] An optional humidity sensor(s) may monitor the outside
humidity and humidity inside, in order to ensure the internal
environment does not fall outside the optimum range of 30-70%. For
example when raining or it is very humid outside, less ventilation
may be provided in order to prevent the humidity rises above these
parameters.
[0145] An optional CO2 or other pollutant sensor may be provided to
monitor indoor air quality and used to control the amount of fresh
air/ventilation provided to the space. Alternatively infra red,
motion or proximity sensors may be used to detect occupants or the
number of occupants. This is advantageous when the area to be
serviced has a variable number of occupants, or usage and therefore
the ventilation rate can be varied to better serve the occupants
and/or save energy.
[0146] Contacts can be placed inside the pack, and the electrical
resistance across the phase change material can be measured. The
resistance changes as the PCM melts or solidifies. Care needs to be
taken that the pack does not `short` the measurement circuit.
[0147] A temperature sensor can be used inside the pack to measure
the temperature of the PCM itself or placed on the surface of the
pack to measure the outside temperature of the pack. One potential
problem with both this method and the previous one is that they
only measure in a single location, and may result in localised
effects, or they require multiple sensors. The sensors also have to
be able to be disconnected as the packs are removable.
[0148] With either of these methods the system can monitor the
state of the PCM. If the PCM does not reach the desired temperature
after a certain time, e.g. when cooling at night, then the control
system will turn the booster on.
[0149] Typically a temperature sensor and preferably a humidity
sensor are placed at the start and end of the PCM heat exchanger.
An algorithm can then be used to calculate the state of the PCM and
whether the booster is needed.
[0150] The power output of the heat exchanger is governed by the
following equation:
P=.rho..v.c.h(.DELTA.T)
[0151] P--power (KW or KJ/s)
[0152] .rho.--density of air or HT fluid (.about.1.2
Kg/m.sup.3)
[0153] v--volume flow rate (m.sup.3/s)
[0154] h--heat exchanger efficiency (%)
[0155] .DELTA.T--difference in temperature between start and end of
heat exchanger
[0156] The flow rate can be determined by the control system from
the fan speed and whether the air is recirculated/mixed or pulled
in from outside (as the resistance will change). Apart from the
temperatures the other variables are constant.
[0157] If the temperature of the air out of the heat exchanger is
greater than a certain value, e.g. 18 C then the PCM needs further
cooling. The system knows the total energy stored in the PCM (from
the latent heat KJ/KG and the mass of PCM), and the rate that the
system is recharging the PCM based on the equation above. If the
temperature difference between the air in and air out of the heat
exchanger is small, or if the system calculates that the recharge
rate will not freeze all the PCM in the given time period (e.g. 6
hours overnight), then the system can increase the air flow via the
fan speed to get the required recharge rate, or turn on the booster
system to lower the temperature of the air entering the heat
exchanger. When the temperature difference between the air entering
the heat exchanger and leaving it is small, then the system knows
that no further recharging is possible unless the outside
temperature drops further (in which case the fan speed can be
turned down/off to save energy) or the booster is turned on to drop
the temperature further. The system may also take into account
approximate
[0158] In a similar way the system can calculate whether the
current rate of cooling will mean the system will run out of
cooling before the end of the day, and therefore turn the booster
on, increase or decrease the air flow rate.
[0159] FIG. 32 show an embodiment of the fluid conditioning
apparatus in which the secondary heat exchanger can be bypassed
when not in use, so that energy is not wasted when the secondary
heat exchanger is not in use. In this embodiment, air from outside
the building enters the system through a first filter 401. Air from
the room to be heated/cooled enters through a second filter 402. A
valve 403 selects the proportion of air from outside and from
within the room that is supplied to the fan 404 and through the PCM
heat exchanger 405. A second valve 406 selects the proportion of
air that is returned to the outside or back to the room after
passing through the PCM heat exchanger.
[0160] An evaporator and secondary heat exchanger 407 is provided
in the path of the air from the first valve 403. A bypass valve 408
selects whether the incoming air passes through the secondary heat
exchanger or not. A condenser air conditioning unit 409, usually
located outside the building comprises a condenser 410 and a
compressor 411. Any chiller unit could be used. An expansion valve
412 is provided in the upstream path from the air conditioning unit
409.
[0161] FIG. 33 shows a further version of the fluid conditioning
apparatus in which the same reference numerals are used for the
same components shown in FIG. 32. In FIG. 33, an indirect
evaporator 413 is provided to separate the wet side of the system
from the air entering the controlled environment so that there is
no increase in humidity in the controlled environment. The
evaporator 413 may be located remotely. In this embodiment the
first valve 403 acts as a bypass valve 408.
[0162] FIG. 34 shows a further version of the fluid conditioning
apparatus in which the same reference numerals are used for the
same components shown in FIGS. 32 and 33. In this embodiment, a
remote booster unit 415, which may use any suitable heat exchanger
is connected to the PCM heat exchanger 405 via an input duct 416.
An exhaust duct 417 is provided to the outside environment. In FIG.
34, the outside perimeter of the room to be serviced is indicated
by reference number 418. A weather louvre 419 is provided with an
additional fan 420 for pulling air out of the room 418 so that the
load on the main fan 404 is reduced.
[0163] FIG. 35 shows a further version of the fluid conditioning
apparatus in which the same reference numerals are used for the
same components as the preceding figures. In FIG. 35, the dashed
lines show how the system can be divided up into a control unit
module 421, a bypass module 422 and a booster module 423 connected
by appropriate ducting. The booster module 423 can also be placed
between the control module 421 and the PCM heat exchanger 405.
[0164] Throughout the description and claims of this specification,
the words "comprise" and "contain" and variations of them mean
"including but not limited to", and they are not intended to (and
do not) exclude other moieties, additives, components, integers or
steps. Throughout the description and claims of this specification,
the singular encompasses the plural unless the context otherwise
requires. In particular, where the indefinite article is used, the
specification is to be understood as contemplating plurality as
well as singularity, unless the context requires otherwise.
[0165] Features, integers or characteristics described in
conjunction with a particular aspect, embodiment or example of the
invention are to be understood to be applicable to any other
aspect, embodiment or example described herein unless incompatible
therewith. All of the features disclosed in this specification
(including any accompanying claims, abstract and drawings), and/or
all of the steps of any method or process so disclosed, may be
combined in any combination, except combinations where at least
some of such features and/or steps are mutually exclusive. The
invention is not restricted to the details of any foregoing
embodiments. The invention extends to any novel one, or any novel
combination, of the features disclosed in this specification
(including any accompanying claims, abstract and drawings), or to
any novel one, or any novel combination, of the steps of any method
or process so disclosed.
* * * * *