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Recycling of Condensed Water from an Air
Conditioning Unit
Md. Washim Akram*, Rifatul Mursalin, Md. Murad Hassan, Md. Rashedul Islam, Sirajul Karim Choudhury
Dept. of Mechanical Engineering, Rajshahi University of Engineering & Technology
*washimme11ruet@gmail.com
Abstract— Treatment of waste water or recycling of water for
reusing of different beneficial purposes like drinking, irrigation,
toilet flushing, and industrial processes saves water resources. It
also offers economic savings. The main purpose of installing an
air conditioning unit is to get the cooling effect. Water is
produced from air conditioners, with no cost as a by-product
which is usually unused in Bangladesh. This thesis aims to
determine the important properties of condensed water of an air
conditioning unit. This study also illustrates the uses of this
unused valuable water. Water analysis is based on chemical tests
as total hardness, turbidity, dissolved solids, alkalinity, electrical
conductivity, copper, lead, iron, manganese, and chloride
content, dissolved oxygen, pH, chemical oxygen demand, total
suspended solids, biological oxygen demand, and corrosivity.
Meanwhile, sample quantity measurements were performed.
Attained water has to some extent basic pH, close to neutral
range. Total dissolved solids, copper, lead, total hardness,
electrical conductivity, and alkalinity of condensed water are in
very short ranges. In average, every 2-ton air conditioner formed
25 liters of water each day. This research shows the feasibility
study of using this condensed water in the battery, automobile
radiator, boiler, toilet flushing and washing clothes.
Keywords: Recycling; Condense water; Air conditioning unit;
Properties of water.
I. INTRODUCTION
Water is an indispensable requisite of lifespan in lieu of
consumption, domestic, engineering as well as farming
usages. Its superiority as well as the amount which differ over
planetary and time, are significant constituents in the essential
growth of every zone. Any modification in the normal
superiority of water may interrupt the steadiness scheme as
well as it would convert unhealthy for nominated
consumptions [1]. It is assessed that 70% of universal water is
consumed for farming purpose, with 15-35% of irrigation
drawings actuality unmaintainable [2]. It receipts about 2,000
- 3,000 liters of water to yield sufficient nutrition to gratify
one person's day-to-day nutritive requirement [3]. It is
projected that 8% of universal water usage is for household
aims. Water consumption for agriculture irrigation, livestock
drinking, domestic use, and industrial purposes described in
details. [4] 22% of worldwide water is used in industry [5]. Of
all the water available on Earth, 97.6% is concentrated in the
oceans. Freshwater corresponds to the remaining 2.4%. Of this
2.4 %, only 0.31% is not concentrated on the Poles in the form
of ice. Of all the water on Earth’s surface, less than 0.02% is
available in rivers and lakes as fresh water ready for
consumption [6].
The topic water reuse boosted several studies and research,
mainly in other countries with the higher scarcity of this
element. In most cases, water reclamation takes place in
industries and agriculture [7]. Projects aiming at effective
water management, treatment, and reuse have been implanted
in Mediterranean and Middle East countries, seeking to
increase water supply security by raising public awareness and
implementing innovative solutions to each reality [8]. The
scale, water quality, safety criteria and water reuse
management need to be studied and improved. Water reuse
has been carried out in large scale in countries such as China,
where several treatment stations are operational and present
increasing results in terms of water reuse percentage to
improve environmental sustainability [9].In cities where there
is a favorable history of precipitation, studies proposing
techniques for building water reuse systems have been
developed, and some of them corroborate the efficiency by
reducing water demand by 35%, such as in schools in the
district of Taipei [10]. This water has relatively good quality
and after a few treatment stages, it could be used as drinking
and non-drinking water, meeting several demands in the
operation of a building [11]. Every hour a 2-ton air conditioner
discards 3.5 to 4.5 liters water [12]. The average factory water
consumption in Bangladesh is estimated to be around 250 to
300 liters of water per kilogram of fabric produced [12]. This
is the identical to the daily usage of water for two people in
Dhaka. For comparison, the global benchmark for fabric
production is 100 liters of water per kg [13].
The vital focus of this study is to ascertain the properties of
the condensed water and analyzing the feasibility of the water
as the use of different sectors like battery water, water used in
boiler, industrial purpose, irrigation, washing cloth, fish
culture in the aquarium, drinking water source.
II. METHODOLOGY
A. Collection of Condensed Water
Contemporary air conditioning schemes are not planned to
pull air hooked on the chamber from the outdoor, they simply
recirculate the progressively cold air on the intimate. Since
this intimate air continuously has certain quantity of humidity
adjourned in it, the refrigerating share of the method
continuously reasons atmospheric hot water vapor to minimize
on the refrigeration loops as well as to drop from them
downcast on top of a fastening plate at the bottommost of the
part from which it essential then be transmitted exterior,
generally through a gutter hole.
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Fig. 1: Formation process of water in air conditioning unit
The quantity of water vapor held in the air is dependent on
temperature. More water vapor can be held at higher
temperature. As temperatures start falling the volume of water
vapor that can be held in the airborne falls. At dew point, the
water vapor will start forming water droplets on surfaces
lower than that temperature. Water formation in air
conditioning unit can be shown in Fig. 1.
The water is produced in the internal unit because the
evaporator coils are at a very low temperature usually around
4–50 C [14]. The temperature of the coil surfaces is very much
lower than dew point and when air is blown on evaporator
coils, air cools down and water starts to condense on the
evaporator coils. Then water is drained out through the drain
pipe, which is a split AC is dusted out along with power wires
and copper tubing.
By way of this dampness has not at all disbanded mineral
deposits in it, it not ever reasons inorganic accumulation on
the loops, although if the element is set at its toughest
refrigeration situation as well as occurs to consume
insufficient rotation of air from side to side the loops and
similarly understandings a disappointment of the thermistor
which intelligences the atmospheric temperature in the
chamber, the loop's flippers can progress a coating of frost
which will then raise in addition to finally chunk the rotation
of air on the cold adjacent of the component overall in a
constructive response coil that will reason the creation of a
frost chunk intimate the unit. Merely infinitesimal quantities
of cold air will then maintain to originate from the exhaust
opening till this ice is uninvolved otherwise is acceptable to
dissolve. This will occur straight if the atmospheric moisture
level is little, once ice instigates to the procedure on the
evaporative flippers, it will decrease transmission
effectiveness as well as the reason the growth of additional
ice, etc. A hygienic in addition to the robust rotary fan can
support to stop this, as will rising the goal cool temperature of
the unit's thermostat to a point that the compressor is permitted
to turn off infrequently. Practically water collection from an
air conditioning unit is shown in Fig. 2.
Fig. 2: Sample water collection
Table 1: Conditions and collections of condensed water both
practically and theoretically
Initial Conditions
(Before 20 minutes)
Final Conditions
(After 20 minutes)
Condens
ed Water
(Practica
l)
Condens
ed Water
(Theoreti
cal)
DBT
(ºC)
WBT
(ºC)
RH
(%)
DBT
(ºC)
WBT
(ºC)
RH
(%)
mL/20mi
n
mL/20mi
n
30
27.5
84
28.5
25.5
79
1050
1124
28.5
25.5
79
27.5
24
75
710
756
27.5
24
75
26.5
22.8
72
465
494
26.5
22.8
72
26
22
70
430
446
26
22
70
25
20.8
68
415
442
25
20.8
68
24
19.6
66
415
440
B. Experimental Data
Date: 17/06/2016
Unit Capacity: 2 TR
Model no: GS-24V/I
Location: Heat Engine Lab, Rajshahi University of
Engineering and Technology (RUET)
C. Typical Calculation for Condenced Water (Theoretically
Calculated)
Initial Condition:
Dry bulb temperature (DBT) = 300 C
Wet bulb temperature (WBT) = 27.50 C
Relative humidity (RH) = 84%
Final Condition:
Dry bulb temperature (DBT) = 28.50 C
Wet bulb temperature (WBT) = 25.50 C
Relative humidity (RH) = 79%
Air Flow Rate, V= 1000 m3/hr
By using this data, from Psychrometric Chart
Specific volume of air, Vs = 0.89 m3/kg dry air
Specific humidity in Initial Condition, W1= 0.0225
kg/kg of dry air
Specific humidity in Final Condition, W2= 0.0195
kg/kg of dry air
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Calculations
Amount of Water Condensed
= (W1 -W2) ma [Where, ma is mass of air]
= (W1 -W2) V/Vs
= (0.0225-.0195) (16.67/0.89) kg/min
= 0.0562 kg/min
= 1.124 kg/20min = 1124 ml/20min = 3372 ml/hr
III. RESULTS
A. Comparison Diagrams
Fig. 3 depicts that the theoretical value of condensed water is
always greater than practical value because of some water
losses by evaporation, leakage problem. The variation of
condensed water quantity with relative humidity can be also
shown by this graph.
Fig. 4 depicts the average value of relative humidity of
different months in Rajshahi, Bangladesh. In Bangladesh,
December to March is winter season that’s why relative
humidity level is low. On the other hand, the remaining
portion of year is monsoon and summer season that’s why the
relative humidity level is high. Due to higher relative humidity
the amount of obtaining condensed water is high in summer
season. The amount of condensed water produced in different
seasons in Rajshahi, Bangladesh can be easily obtained by co-
relating Fig. 3 and Fig. 4.
Fig. 3: Condensed water vs. relative humidity graph
Fig. 4: Relative humidity of different months in Rajshahi, Bangladesh
[15]
Table 2: Tested properties of condensed water
Water Quality
Parameters
Concentration
Bangladesh
Standards
[16]
Unit
Copper (Cu)
0.26
1
mg/L
Dissolved Oxygen
6.15
6
mg/L
Electric
Conductivity
40
-
µS/cm
Lead (Pb)
0.002
0.05
mg/L
Nitrogen (Nitrate)
3.1
10
mg/L
pH
7.2
6.5
-
8.5
-
Total Dissolved
Solids (TDS)
19
1000
mg/L
Total Suspended
Solids (TSS)
1.0
10
mg/L
Hardness
40
200
-
500
mg/L
Turbidity
4.28
10
NTU
Iron (Fe)
0.09
0.3
-
1
mg/L
Manganese (Mn)
0.09
0.1
-
Chemical Oxygen
Demand (COD)
6.23
4
mg/L
Biological Oxygen
Demand (BOD)
22
0.2
mg/L
Alkalinity
27.6
-
mg/L
Chloride
0.6
150
-
600
mg/L
Corrosivity
40
-
µm/year
B. Properties of condensed water
The quality of the water such as Hardness, Chloride, Acidity,
Chemical Oxygen Demand (COD), Alkalinity, Iron,
Corrosivity, Turbidity, PH and other properties were
experimentally ascertained by using IS-3025 (Reffired-2003)
method. Properties of condensed water compared with the
properties of water in Bangladesh standard (Properties of
water according to the Bangladesh Water Development Board)
which follows the WHO (World Health Organization)
guideline are shown in table 2.
C. Uses of condensed water
Boiler purposes
The main purpose of the boiler is to produce steam by burning
different types of fuel in its combustion chamber. So it’s
required impurities free water. But, natural water supplies
contain solid, liquid and gaseous impurities. In the water
intended for steam boilers, the salts of calcium and
magnesium are extremely harmful and when contaminated
water is heated and steam generated they precipitate as solid
residue and form a hard scale on the wall surface. The scale
hampers the process of heat transfer. The presence of mineral
acids in water is undesirable as it may result in a chemical
reaction with boiler materials which causes the troubles.
That’s why it is very important to supply water in the boiler
free from these types of impurities, and condensed recycling
water is appropriate for this purpose.
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Scale formation
Impurities available in the water cause scale formation in the
boiler drums of feed water piping system and header tubes.
This will reduce the heat transfer rate and will cause
overheating of tubes which may result in blistering and
rupturing. The scale is produced because of principally salts of
calcium as well as magnesium. When the scale has formed the
tubes should be scrubbed by way of water or else electronic
power-driven rotating brushes as well as scissors which are
struggling through the pipes through boiler repairs.
Corrosion
Corrosion may occur in the boiler shell, tubes, and plates due
to acidity present in water. This reduces the life of
construction materials. Corrosion is the damaging translation
of metallic hooked on oxides otherwise salts. Corrosion takes
place due to the presence of oxygen, carbon dioxide or
chlorides dissolved in water.Corrosion due to oxygen
produces small pits.
Foaming and Priming
A layer of foam is caused in the boiler drum by soluble and
insoluble salts and organic impurities which are carried in
suspension. Foaming prevents the free escape of steam
bubbles as they rise to the surface of the water. Oil and other
impurities which may be present in boiler water may cause
foaming.
Embrittlement
Caustic embrittlement is caused due to caustic impurities,
certain concentration of sodium hydroxide present in water.
Due to this, the boiler metal becomes brittle and inner cracks
appear along seams below the water level. At this condition,
the surface water need proper treatment to make the water free
from impurities. The impure water is chemically treated in
different ways depending upon the nature and concentration of
impurities as a result overall cost increases. But the water
which is condensed from an air conditioning unit is free from
any impurities like aluminum sulfate, sodium sulfate or
ferrous sulfate, oxygen, carbon dioxide or chlorides and other
mineral salts. So this water can be used in a boiler to produce
steam without any treatment which is more economical.
Radiator water
Radiator is used to cool internal combustion engine when
heavy cooling is required. In radiator water is used as coolant.
So water is not likely to coagulate, and sometimes different
types of supplementary materials like antifreezes are used to
make it suitable for environment. Due to the use of surface
water which contains Iron 0.3-1 mg/L and a large amount of
dissolved oxygen and other solid particles [17]. In automobile
radiator, those water component produce scrap and corroded
which is shown in Fig. 5. As a resulting lifetime of radiator
reduced significantly. But according to laboratory test report,
the iron content in the air conditioning condensed water is
0.09 mg/L and other solid particles contained less than surface
water. So this water is suitable for radiator purpose instead of
surface water.
Fig. 5: Damaged radiator due to using surface water
Battery Water
There are several plates inside the battery which are enclosed
with water and makes it work. This water fragmented into
hydrogen and oxygen gas by the chemical reaction throughout
the operation. These gases vaporize from the battery as well as
through time water level reduces. To preserve the battery
perform proficiently, it is significant to topmost it up with
purified water. These mineral deposits as well as salts plug the
holes and create a coating on the plates, distressing the
standard electro-biochemical reaction that produces power in
the battery. Attendance of such organic ions can extremely
decrease the lifetime of the battery. Clarifying blow water
simply eliminates the postponed substance but not the
disbanded mineral deposits as well as non-ionic composites.
Distilled water comprises no liquefied mineral deposits, salts,
biological as well as inorganic composites that might damage
the battery. The comparison of battery water and condensed
water properties can be shown in Table 3.
Most of the properties of condensed water are similar to the
battery water specification. Only electrical conductivity, as
well as total dissolved solids, are slightly dissimilar to the
battery water. Electrical conductivity depends on the amount
of total dissolved solids. Provide proper purification amount of
dissolved solids can be reduced. Then the condensed water
can be used as battery water.
Table 3: Battery Water and Condensed Water Properties
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IV. DISCUSSION
The existence of whole world is depend on water. Day by day
the demand of water is increased due to the technological
development of the world. At the same time the sources of
water decrease gradually. In this work to find out that air
conditioning unit is an important source of water and suitable
sector. In a normal sense, the amount of condensed water from
an air conditioning unit is very small quantity. But in practical
view a 2-ton capacity air conditioning unit condensed average
3 liters/hour and the properties almost distilled quality. In this
source of water having some problem as like as it depends on
the season. At the time of summer season, this water is
obtained as much as calculated value. It also depends on the
relative humidity of air. If the humidity increases the amount
of condensed water also increased and vice –versa. Besides
some of the water, it loses due to leakage and evaporation.
This loss can be minimized by providing proper carrying and
collecting system. There is no excess amount of energy
required to collect the water and no additional cost is required.
That’s why it is economically feasible to collect and use the
water.
V. CONCLUSION
The biochemical superiority of the experienced samples be
able to understand, the water afterward a modest
decontamination, will have no opposing consequence on users
healthiness, but of course, plenteously of water for ingestion
deprived of management is not suggested. As stated, the
condensate water has appropriate excellence for numerous of
industrialized usages whereas this water resource is free, no
price for management is compulsory, no opposing effects on
surroundings, no injurious belongings for tools as well as no
healthiness hazards. This water can effectively utilize in
automobile battery, radiator water, toilet flushing, industrial
purposes, washing cloth, fish culture in aquarium, and
irrigation purpose. This condensed water can also be used as
drinking water with conventional treatment followed by
disinfection. Consequently, it necessitates a wide-ranging
strategy as well as organized it into the water assortment,
storing in addition to end it greatest utilized as directed. By
recycling water from the different sectors such as discarded air
conditioning water, the problem of scarcity of water can be
minimized.
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