Recair Enthalpy
saving energy in comfort
We need air, always and everywhere; in good quality!
Figure 1: Comfort zone
The air quality inside our buildings is not always what
100
it should be.
80
Always and everywhere! That is why we equip our build-
70
We assume air is healthy and of a comfortable temperature, with as little pollution as possible.
Out of this perception we developed the Recair Enthalpy.
relative humidity RH (%)
Comfortable clean air. Temperature, humidity and velocity…
ings with air handling systems.
too warm
50
40
30
20
• brings fresh air to your office and home,
10
Wherever you are, regardless of the season.
too cold
60
A recuperator which (more than any other available today):
•provides a comfortable temperature and humidity.
too humid
90
too dry
0
12
14
16
18
20
22
24
28
air temperature (°C)
maximum comfort (pleasant)
limited comfort
2
30
32
Recair Enthalpy
Ideal for different climates
The Recair Enthalpy is an excellent choice for ventilation
Super-efficient
systems operating in a wide range of climates, including
The Recair Enthalpy is a new unique heat recovery core
those areas which experience more extreme weather.
for implementation in heat-recovery ventilation (HRV)
In cold climates the Recair Enthalpy offers:
units. It is the next step ahead in recuperation technology
• recovery of heat and moisture,
following the Recair Sensitive.
• prevention of a dry indoor climate
•prevention of blocked return air flow through the core
Where the Recair Sensitive is meant for recovery of
because of freezing. In other words, it keeps the high
sensible- or thermal heat from an air flow only, the Recair
performance, also under freezing conditions.
Enthalpy can also recover the latent energy (heat stored in
In warm humid climates the Recair Enthalpy features cool-
the moisture of the air).
ing and dehumidification of fresh ambient air.
Based on its famous triangular duct counterflow design,
Manufacturers of ventilation systems, architects and indi-
Recair Sensitive heat exchanger cores excel in the highest
vidual home owners in Europe, North America and Asia
heat recovery effectiveness (> 90%) at lowest pressure
are showing increasing interest in the Recair Enthalpy.
loss (low fan power consumption).
No wonder, since it creates the ideal indoor climate –
with healthy fresh air, at the right temperature and the
With the Recair Enthalpy, Recair again raises the standard
right humidity – in a way that is affordable, cost-effective,
in the market for heat recovery components. The Recair
energy-efficient and environmentally conscious.
Enthalpy provides the user with not only effectiveness
higher than 90% for both sensible and latent heat, but
also, as first enthalpy heat exchanger core in the world,
•the most effective heat recovery (> 90% for both
the Recair Enthalpy features control over the amount of sensible and/or latent heat recovered, from zero to maximum.
Benefits of the Recair Enthalpy:
sensible and latent),
• cool, fresh supply air at night, during hot summers,
• no freezing of the exchanger, even in cold climates,
With the Recair Enthalpy, more than in the past, it is possible to recover and efficiently re-use energy generated
•prevents a too dry or humid indoor climate (controlled latent recovery),
for heating and cooling interior spaces, while optimising
• affordable and convenient,
the indoor air quality which is crucial for a healthy indoor
• elimination of odours,
climate. It is ideal for use in balanced ventilation systems
• preventing build-up of mould and mildew,
in homes, offices and many other applications. It also al-
• significantly reduced energy costs,
lows users to substantially reduce their basic energy costs
• little maintenance.
and reduce their dependence on fossil fuels.
The Recair Enthalpy is the first enthalpy recuperator that
enables you to regulate indoor humidity, so that your
Different areas of application
interior climate is never too dry or too humid.
Recair Enthalpy products can be used at home, in offices,
schools, and even in greenhouses!
3
Working principle Recair Enthalpy
The Recair Enthalpy is a follow-up development on the
next (fresh air) period of the duct. This process is driven by
Recair Sensitive. In view of its possibilities, an entirely
the vapour pressure difference of water, causing transport
new innovative recuperator is created (patented).
of water only, no particles are moved to or from the duct
walls. This implies no transfer of contamination, only water.
The heart of every Recair Enthalpy is a Recair Sensitive.
The plastic heat exchanger, with all its strong character-
During times of non condensing conditions, inside the Re-
istics arising from the dense packaging of small stable
cair Enthalpy, moisture transfer cannot take place, thus no
triangular ducts, ensures the necessary uniform heat flow
reason for valve movement. At times of non-condensation
over the core (see brochure Recair Sensitive) to warrant
the Recair Enthalpy performs equal to a Recair Sensitive.
the highest effectiveness. This also means that the working
However when air conditions cause condensation in the
principle of the Recair Enthalpy – as far as the moisture
Recair Enthalpy, moisture can be recovered by operating
transfer is concerned – is not based on the use of mem-
the valves. Switching intervals vary from long periods (only
brane technology. For reason of moisture transfer control,
a couple of switches a day during moderate condensing
the Recair Enthalpy works on the principle of alternation
conditions) to short periods (a switch every 10 minutes in
of the air flow direction through the small inner ducts of
severe conditions). Under these circumstances the Recair
the heat exchanger core.
Enthalpy will prove itself most worthwhile, as than the heat
recovery is at maximum.
The Recair Enthalpy achieves this by the air tight mounting of 4 sliding valves to a Recair Sensitive (every core
The working principle is –more graphically– explained
handles two air flows; every flow has an intake- and
below. First for cold climate conditions and second for a
outlet opening. leading to 4-valves). A valve system
warm-humid climate in which the heat exchanger is used to
consists of a frame in which a sliding valve is mounted.
(pre-)cool and dehumidify the fresh air before entering the
A labyrinth on the valve assures an air tight sliding seal.
building.
Every valve is equipped with its own motorized drive.
Figure 2.1: cold climate
stale air
waste air
fresh air
fresh air
stale air
waste air
outside air
fresh air
IIc
warm
outside air
IIb
warm
stale air
flowing through a duct, with the air flowing through the
IIa
warm
waste air
Every valve operation causes an inter-change of the air
I
warm
fresh air
controls of the Heat Recovery Ventilator Unit.
stale air
Enthalpy sees to it that valves act as instructed by the
waste air
An electronic motion controller belonging to the Recair
neighbouring duct. In other words, a primary air duct
will become a secondary air duct (with movement of the
valves also the flow direction in the ducts reverses), and
sate or even ice during a waste air period of the duct
cold
cold
cold
outside air
In this way, moisture deposited at the duct wall as conden-
outside air
the secondary air duct will be primary air duct.
cold
(colder climates) will sublimate cq. evaporate again in the
4
I
cold
IIa
IIb
IIc
cold
cold
cold
cold
fresh air
outside air
stale air
waste air
stale air
waste air
fresh air
fresh air
outside air
cold
stale air
waste air
fresh air
fresh air
outside air
IIc
cold
stale air
IIb
cold
waste air
IIa
cold
fresh air
stale air
waste air
fresh air
end of the waste duct. Then the valve will operate and the
stale air
cold
outside air
I
with moisture condensing/freezing towards the outside
passing through the right-hand duct – starts to evaporate
cold
Figure 2.2: warm-humid climate
left hand duct and waste air through the right-hand duct,
flow alternation takes place (phase II). The fresh air – now
cold
waste air
At the initial state (phase I), fresh air passes through the
outside air
stale air
outside air
waste air
IIc
warm
stale air
IIb
warm
waste air
IIa
warm
fresh air
I
warm
the condensate (phase IIa), while moisture in the waste
air – now passing through the left-hand duct – begins to
condense at the same relative position in the duct as the
position, as where the moisture freezes in the adjacent
warm
warm
warm
outside air
The same holds for ice, which is sublimated at the same
outside air
evaporation takes place in the adjacent duct (phase IIb).
warm
duct. Finally, (phase IIc), all water will be evaporated in
the fresh air flow. Simultaneously the maximum level of
Phase 1; fresh air passes through the left hand duct, now
condensation has been achieved in the waste air duct.
cooling down with moisture condensing towards the end
At this point, the mirror-image of the situation as shown in
of the fresh air duct, while waste air is gaining heat on
phase I is reached. Now the direction of the air flows is
its way through the right-hand duct leaving the building.
normally reversed to repeat the whole process. If humidity
After alternating the flows (phase IIa), the waste air will
production indoors is too high, periods of valve movement
leave the building through the left-hand duct evaporating
can be controlled at different intervals, causing excess
the condensate, while moisture starts to condense from
humidity to be removed from the Recair Enthalpy as con-
the fresh air at exactly the opposite point in the duct of the
densate. Also the sensible heat transfer can be controlled.
evaporation. When operating the valves periodically, fresh
By using the valves to direct one of the flows through both
air is de-humified. The end of the cycle occurs when all
duct types of the core (primary and secondary), leading
condensate has been evaporated in the used air flow, and
the other flow over a bypass round the recuperator.
the maximum level of condensation has been reached in
the opposite air duct; the mirror-image of phase 1.
The next step could be another flow alternation. Depending on the decision, whether or not, to operate the valves
synchronous or a-synchronous, the Recair Enthalpy can
act as a full enthalpy heat exchanger or as a controllable
partly enthalpy recuperator.
And with one switching interval going to infinity, as a sensible heat exchanger. Having the possibility of choice to
recover moisture or not, realizes the right level of comfort.
5
Anchorage - Alaska
Climate of Anchorage, Alaska
The climate of Anchorage, Alaska (see fig. 3.1) is sub-
air entering the Recair Enthalpy from the opposite side
arctic with short, cool summers. Average daytime summer
increases in temperature and humidity (sublimation of ice
temperatures range from approximately 55 to 68 °F (13 to
and evaporation of condensate from the duct walls depos-
26 °C); average daytime winter temperatures are about
ited during the former cycle). This sublimation/evapora-
5 to 30 °F (-15 to -1 °C). Anchorage has a frost-free
tion is driven by the difference in vapour pressure.
growing season that averages slightly over 100 days.
Average January low and high temperatures are 9 /22 °F
Remarkable here is, that due to the fact that the air
(-13 /-5 °C).
flow is gaining temperature, it is able to evaporate the
condensate from the walls all the way through the heat
Figure 3.1: Climate Anchorage, Alaska
60
average relative humidity
temperature [°F]
50
30
rated and the heat exchanger interior becomes dry.
In
RH=100%
90
this case at a temperature of 46 °F (8 °C). From this mo-RH=80%
80
ment on the air (still inside the heat exchanger) will only
70
increase in temperature until it leaves the Recair Enthalpy
60
40
average temperature
50
40
30
20
10
Jan Feb Mar Apr May Jun
8
inside
ture of just over 64 °F (18 °C) and 53% relative humidity.
fresh
RH=40%
6
True, a sensible heat exchanger would offer the same
temperature, but with a much lower relative humidity (less
than 20%)! And also the Recair Enthalpy will not freeze
10
waste
under circumstances described here
above. Table 1.1
4
RH=20%
2
ambient
shows the savings belonging to this example.
Jul Aug Sep Oct Nov Dec
month
-30
-20
-10
0
10
20
0
30
-22
-4
14
32
50
68
86
Table 1.1: gain from Recair Enthalpy to described
The Recair Enthalpy is charged with two air flows; at one
ambient
temperature
[°C]; [°F]
example. Calculations based on 150
[m3/h],
21[ °C],
side stale air enters with a temperature of 70 °F (21 °C)
RH 50 % (Imperial: 90 [SCFM], [70 °F], RH 50%).
and a relative humidity of 50%, while, at the same
time, outside air, flows in from the opposite side, at
example
inside
outside
fresh air
18 °F (-8 °C) and 85% relative humidity.
T [°F] ([°C])
70 (21)
18 (-8)
64 (18)
85
53
RH
50
Inside the heat exchanger stale air immediately starts to
gain [W]
transfer heat to the fresh air flow. This drop in temperature
total
1987
causes the relative humidity to increase to 100% (at this
sensible
1349
point the air is 50 °F and saturated). From this moment on
latent
638
moisture will condense at the duct walls inside the Recair
Enthalpy until temperature drops below 32 °F, than moisture
will even freeze. Waste air leaves the Recair Enthalpy and
exhausts to outside at a temperature of 21 °F (-6 °C) with
100% relative humidity. At the same time, the cold outside
6
10
RH=60%
into the building as fresh comfortable air with a tempera-
20
0
0
12
100
relative humidity [%]
70
exchanger until all ice and moisture is sublimated/evapo-
Figure 3.2: psychromatic chart in case of a condensation
and freezing in a Recair Enthalpy (dots represent hourly
temperatures and humidities for a representative year).
12
RH=100%
RH=80%
8
inside
RH=40%
fresh
6
4
RH=20%
waste
moisture content [g/kg]
10
RH=60%
2
ambient
-30
-20
-10
0
10
20
0
30
-22
-4
14
32
50
68
86
ambient temperature [°C]; [°F]
Table 1.2: savings Recair Enthalpy on yearly basis for
Anchorage. Calculations based on 150 [m3/h], 21[ °C],
RH 50 % (Imperial: 90 [SCFM], [70 °F], RH 50%).
Recair enthalpy
RE400
Anchorage
yearly gain [GJ]
[kWh]
heating total
37
10278
sensible
27
7417
latent
10
2861
cooling total
0
11
sensible
0
11
latent
0
0
7
Miami - USA
Climate of Miami, Florida
Miami has a tropical climate with hot, humid summers,
and warm, dry winters. However, the average monthly
Recair Enthalpy cooling and dehumidifying
warm humid outside air
temperature for any month has never been recorded
as being under 64 °F (18 °C) (January averages
(Products operating according to the working principle here
67 °F – 19 °C). Most of the year is warm and humid,
described are subjected to patent rights)
and the summers are almost identical to the climate of
the Caribbean tropics. In addition, the city gets most of
Stale air of 72 °F (22 °C) is cooled by means of an air
its rain in summer (wet season) and is relatively dry and
conditioner to 52 °F (11 °C). In this case air may be
cool in winter (dry season).
cooled for 555 W just to avoid condensation. Stale air of
52 °F (11 °C) will then enter the Recair Enthalpy.
A typical summer day does not have temperatures below
75 °F (24 °C). Temperatures in the high 80’s to low 90’s
Figure 4.2: psychromatic chart in case of a condensation in
(30-35 °C) accompanied by high humidity are often
a Recair Enthalpy (dots represent hourly temperatures and
relieved by afternoon thunderstorms or a sea breeze that
humidities for a representative year).
develops off the Atlantic Ocean. During winter, humidity
100
25
RH=100%
is significantly lower, allowing for cooler weather to
average temperature
RH=80%
develop. Minimum temperatures90during that time are
Figure 4.1: Climate Miami, Florida
50
90
40
average temperature
80
30
temperature [°F]
70
20
average relative10
humidity
60
0
50
Jan Feb Mar Apr May Jun
40
Jul Aug Sep Oct Nov Dec
month
ambient
100
60
50
30
20
20
10
10
0
0
Jan Feb Mar Apr May Jun
Jul Aug Sep Oct Nov Dec
month
fresh
10
cooled
80
70
15
RH=100%
RH=40%
90
40
30
RH=60%
waste
inside
relative humidity [%]
60
relative humidity [%]
70
usually range between 70 and 77 °F (19-24 °C).
average relative humidity
RH=20%
moisture content [g/kg]
20
80
around 60 °F (15 °C), and the equivalent
maxima
5
5
32
41
10
15
20
50
59
68
fresh
25
30
0
35
77
inside
86
95
outside temperature
[°C]; [°F]
cooled
20
RH=60%
Cooled stale air will cause condensation of moisture from
RH=40%
RH=20%
15
10
5
the fresh air flow inside the heat exchanger. The process of
evaporation in the0waste 5air flow
needs15energy.
This 25
energy30
10
20
[°C];
[°F]
is supplied by the condensationoutside
takingtemperature
place in the
opposite
32
41
50
59
68
77
86
flow. The psychromatic chart (figure 4.2) shows a schematic
representation of the condensation and evaporation in the
Recair Enthalpy.
8
RH=80%
ambient
waste
0
25
0
35
95
Table 2.1: gain from Recair Enthalpy to described example.
A sensible heat exchanger core would definitely show a
Calculations based on 150 [m3/h], 22 [°C], RH 50 %
lower performance. As there will be no evaporation in the
(Imperial: 90 [SCFM], [72 °F], RH 50%).
waste air flow. As a result, there is no possibility to transfer
the energy-surplus coming free from the condensation taking
example
inside
outside
fresh air
place in the fresh air flow. In this way less energy transfer
T [°F] ([°C])
72 (22)
82 (28)
55 (13)
means less cooling of the outside air temperature and so a
RH
50
70
100
higher fresh air temperature entering the building.
gain [W]
total
1769
Table 2.3: savings Recair Enthalpy on yearly basis
sensible
816
for Miami. Calculations based on 150 [m3/h],
latent
953
Table 2.2: the performance realized by the Recair Enthalpy.
waste
fresh
22[°C], RH 50 % (Imperial: 90 [SCFM], [72 °F], RH 50%).
Recair enthalpy
RE400
Miami
yearly gain [GJ]
[kWh]
heating total
1
364
sensible
1
358
temperature
[°F ] ([°C]) 79 (26,5) 54 (13)
latent
0
6
relative humidity
[%]
cooling total
42
11583
flow
73
100
[SCFM] 90
90 sensible
20
5500
([m3h-1])
150
150
latent
22
6083
Vapour flow
[Pounds] 6.4
3,6 ([kgh-1])
2,9
1,62
Transferred sensible power [BTU/h] 2787
-2787 (816)
([W])
Transferred latent power
[BTU/h] 3255
([W])
(953)
-3255 Transferred moisture
[Pounds] 3.1
-3.1 ([kgh-1])
1,40
-1,40
By first “investing” 1895 BTU/h (555 W) the Recair
Enthalpy offers 6042 BTU/h (1769 W) cooling power
(2787 BTUh sensible + 3255 BTUh de-humidification).
9
Tokyo - Japan
Climate of Tokyo, Japan
Recair Enthalpy cooling and dehumidifying
warm humid outside air
The climate at Tokyo is moderate and comfortable
throughout the year. It is hot and humid with typhoons
in summer where as the winter is long and dry. Tokyo
enjoys 4 seasons:
(Products operating according to the working principle here
•Spring: March to May. The initial days of spring are
described are subjected to patent rights)
cold but by the month of May, the weather gets warm.
•Summer: June to August. After rainy season, the tem-
Stale air from the building of 21 °C (70 °F) will first be
cooled (by means of an air conditioner) to 10 °C (50 °F).
perature soars to 30 °C along with humidity.
•Autumn: September to November. In the initial days of
In this case air may be cooled for 552 W just before
autumn, summer temperature prevails. But in general,
condensation starts. Stale air of 10 °C will then enter the
the temperature in autumn is pleasant and soothing.
Recair Enthalpy.
•Winter: December to February. Temperature falls to
Stale air will cause condensation of moisture from the
around 2 °C (36 °F).
fresh air flow inside the heat exchanger. The process of
evaporation in the waste air flow will need energy.
Figure 5.1: Climate Tokyo
30
average relative humidity
90
in the opposite flow.
25
RH=100%
RH=80%
80
70
20
15
This energy is supplied by the condensation taking place
60
average temperature
50
40
10
30
5
0
Jan Feb Mar Apr May Jun
Jul Aug Sep Oct Nov Dec
month
ambient
relative humidity [%]
temperature [°C]
25
100
Table 3.1 gain from Recair Enthalpy to described example.
Calculations based on 150 [m3/h], 21[°C], RH 50 %
RH=60%
15
(Imperial: 90 [SCFM], 70 [°F], RH 50%).
fresh
RH=40%
inside
20
example summer inside
outside
fresh air
10
T [°F] ([°C])
70 (21)
82 (28)
54 (12)
0
RH
50
80
100RH=20%
total
sensible
latent
5
25
30
0
35
41
50
59
68
77
86
95
2164
-10
-5
0
141307
23
32
5
10
15
20
857
ambient temperature [°C]; [°F]
The psychromatric chart (figure 5.2) shows a schematic
representation of the condensation and evaporation in the
Recair Enthalpy.
10
gain [W]
10
20
waste
Figure 5.2: psychromatic chart in case of a condensation
in a Recair Enthalpy.
25
RH=100%
RH=80%
20
waste
RH=60%
fresh
RH=40%
inside
15
10
moisture content [g/kg]
ambient
5
RH=20%
-10
-5
0
14
23
32
5
10
15
20
25
30
0
35
86
95
ambient temperature [°C]; [°F]
41
50
59
68
77
Table 3.2 savings Recair Enthalpy on yearly basis for Tokyo.
Calculations based on 150 [m3/h], 21 [°C], RH 50 %
(Imperial: 90 [SCFM], [70 °F], RH 50%).
Recair Enthalpy
RE400
Tokyo
yearly gain [GJ]
[kWh]
heating total
16
4383
sensible
13
3508
latent
3
875
cooling total
18
4931
sensible
8
2239
latent
10
2694
11
Munich - Germany
Climate of Munich, Germany
Munich lies on the elevated plains of upper Bavaria,
Inside the heat exchanger, stale air immediately starts
some 50 km north of the northern edge of the Alps. It
to lose heat to the fresh air flow, causing an increasing
has a modified continental type of climate. Winters are
relative humidity up until 100%. At this point the saturated
rather cold (January mean: 0.5 °C [33 °F]). Summers are
stale air is 11,5 °C (53 °F), moisture will start to condense.
fairly warm (July mean: 19 °C [66 °F]), and temperatures
Further downstream in the heat exchanger freezing will
throughout the year are somewhat reduced relative to
occur on the duct walls of the Recair Enthalpy.
lower-lying parts of Germany due to the altitude.
This condensation/freezing goes on over the remaining
The climate of Munich is strongly influenced by the
length of the trajectory through the heat exchanger.
proximity of the Alps. Winds from the SW to SE lose their
Waste air leaves the Recair Enthalpy at a temperature of
moisture on crossing the Alps, resulting in Föhn condi-
-3,5 °C (26 °F) with 100% relative humidity.
tions in Munich. The Föhn invariably brings warm, dry
weather at all seasons. Temperatures as high as almost
In the mean time, the cold outside air entering the Recair
20 °C (68 °F) in winter, or 35 °C (95 °F) in summer can
Enthalpy from the other side, increases in temperature
occur with Föhn support.
and humidity (sublimation of ice and evaporation of condensate from the duct walls deposited during the former
Figure 6.1: Climate Munich
cycle). This sublimation/evaporation is driven by the
20
average temperature
difference in vapour pressure. Remarkable here is, that
90
thanks to the fact that the air flow is gaining temperature,
70
60
10
50
40
5
30
20
0
Jan Feb Mar Apr May Jun
-5
relative humidity [%]
average relative humidity
Jul Aug Sep Oct Nov Dec
month
10
moisture is evaporated and the heat exchanger interior is
dry. In this case at a temperature of 11 °C (52 °F).
inside
fresh
8
From that moment the air will only increase in temperature until it leaves the Recair Enthalpy into the building
6
as fresh comfortable air with a temperature of just over
4
19,5 °C (67 °F) and a relative
humidity of just over 60%.
waste
ambient
2
0
air flows; at one side stale air enters with a temperature
of 21 °C (70 °F) and a relative humidity of 60%, while, at
the same time from the opposite side, outside air comes in
12
12
walls all the way through the heat exchanger until all the
10
Simultaneously the Recair Enthalpy is charged with two
at -5 °C (23 °F) and 85% relative humidity.
14
it is able to sublimate/evaporate the condensate from the
80
15
temperature [°C]
100
-20
-10
-4
14
0
10
20
30
32
50
68
86
ambient temperature [°C]; [°F]
0
Table 4.1: gain from Recair Enthalpy to described example.
Table 4.2: savings Recair Enthalpy on yearly
Calculations based on 150 [m3/h], 21[°C], RH 60 %
basis for Munich. Calculations based on
(Imperial: 90 [SCFM], 70 [°F], RH 60%).
150 [m3/h], 21[°C], RH 60 % (Imperial: 90 [SCFM],
70 [°F], RH 60%).
example
outside
fresh air
T [°F] ([°C]) 70 (21)
inside
23 (-5)
66 (19)
Recair Enthalpy
RH
90
63
Munich
yearly gain [GJ]
[kWh]
heating total
29
8006
60
gain [W]
RE400
total
1968
sensible
19
5342
sensible
1210
latent
10
2667
latent
757
cooling total
0
86
sensible
0
86
latent
0
0
True, a sensible heat exchanger would offer the same
temperature, but with a much lower relative humidity of
just under 20%! The Recair Enthalpy will not freeze under
circumstances described here above.
Figure 6.2: psychromatic chart in case of a condensationand freezing in a Recair Enthalpy (dots represent hourly
temperatures and humidities for a representative year).
14
10
inside
fresh
8
6
4
moisture content [g/kg]
12
waste
ambient
-20
-10
-4
14
2
0
10
20
30
32
50
68
86
ambient temperature [°C]; [°F]
0
13
Specifications
This document only intends to show the relevant functional
Table 5.1: conditions used for Fig. 7.1.
specifications like effectiveness, pressure loss and dimensions of the Recair Enthalpy. When designing your Heat
heat exchanger RE400
Recovery Ventilator, of course more specific details are
outside RH [%] 80
needed. For the system engineer Recair summarized all
inside temperature [°C] 20
relevant data in a separate document called Recair En-
inside RH [%] 60
thalpy fact sheet. Please contact us to obtain this document.
flow [m3h-1] 150
changing interval [s] 300
Effectiveness
In the Recair Enthalpy moisture will condense (and freeze)
and water (and ice) will evaporate (sublimate) simultane-
Figure 7.1: effectiveness and evaporation as a function of
ously. The thermal effectiveness is approximately the same
the outside temperature.
as for a dry recuperator (see data of the Recair Sensitive).
1,6
1,6
Additional to the sensible heat, the latent heat is trans-
1,4
1,4
ferred. If the effectiveness is defined as (1),
1,2
1,2
Total effectiveness= total exchanged heat
(1)
maximum exchangable sensible heat
1
0,8
0,8
0,6
0,6
0,4
0,4
0,2
0,2
0
-20
The switching interval of the flows hardly influences the
-15
-10
-5
0
5
10
15
0
20
evaporation [kgh1]
the effectiveness will exceed 100 %.
total effectiveness
1
outside temperature [°C]
thermal
total
evaporation
effectiveness. The indoor temperature and indoor RH
will have influence on the total effectiveness, the more
condensation the higher the total effectiveness and the
evaporation rate.
Figure 7.2 shows the effectiveness of the RE400 in warm
humid climates, the conditions are:
Figure 7.1 shows the effectiveness, thermal effectiveness
Table 5.2: conditions used for Fig. 7.2.
2,5
heat exchanger
2
total effectiveness
2,5
RE400
outside RH [%]
2
80
inside temperature [°C]
22
1,5
1
inside
RH [%]
50
1
0,5 [m3h-1]
flow
150
0,5
1,5
0
changing
interval [s]
22
24
26
28
30
300
32
34
outside temperature [°C]
thermal
total
evaporation
14
3
3
temperature for the RE400. Other conditions are:
36
38
0
40
evaporation [kgh1]
and evaporation rate as a function of the outside
1,6
1,6
1,4
1,4
1,2
1,2
1
0,8
0,8
0,6
0,6
0,4
0,4
0,2
0,2
0
-20
-15
-10
-5
0
5
10
0
20
15
evaporation [kgh1]
total effectiveness
1
outside temperature [°C]
thermal
total
evaporation
Figure 7.2: effectiveness and evaporation as a function of
Operates in a wide range of temperatures
the outside temperature.
The Recair Enthalpy range operates effectively in air
2,5
2,5
1,5
1,5
1
1
0,5
0,5
22
24
26
28
30
32
34
36
38
0
40
outside temperature [°C]
thermal
total
evaporation
evaporation [kgh1]
total effectiveness
Available in two sizes
2
2
0
temperatures from -20 to +50 °C (-4 – 122 °F).
3
3
The Recair Enthalpy comes in two standard sizes.
Dimensions
RE 250
RE 400
height [mm]
250
400
width [mm]
360
360
length [mm]
550
550
weight [kg]
6,41
9
The switching interval hardly has influence on the effectiveness as long as the valves are changed before the
length
water drops off. For longer changing intervals the water
layer on the walls will get thicker. The chance of water
dropping off is larger.
Pressure loss
Fig. 8 shows the pressure loss for both recuperators
width
height
(RE250 and RE400) as a function of the flow.
Figure 8: pressure loss as a function of the flow
140
pressure drop [Pa]
120
100
80
RE 250
RE 400
60
40
20
0
0
50
100
150
200
250
300
flow [m3h-1]
saving energy in comfort
15
Recair bv
Vijzelweg 16
NL-5145 NK Waalwijk
P.O. Box 721
NL-5140 AS Waalwijk
Fax +31 (0)416 348 926
[email protected]
www.recair.com
EN 14-10-2011
Tel. +31 (0)416 347 110