effect of some design and operation ......cite this article: hazem m. saleh, ehab m. mina, raouf n....

http://www.iaeme.com/IJMET/index.asp 681 [email protected]

International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 5, May 2017, pp. 681–693, Article ID: IJMET_08_05_075

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=5

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

EFFECT OF SOME DESIGN AND OPERATION

PARAMETERS ON THE PERFORMANCE OF A

WATER DESALINATION UNIT USING

HUMIDIFICATION – DEHUMIDIFICATION

Hazem M. Saleh, Ehab M. Mina, Raouf N. Abdelmessih

Master of Engineering Sciences Student,

Mechanical Power Engineering Department, Ain Shams University, Egypt

ABSTRACT

This paper investigates the performance of an H-DH desalination unit with an

extra condensing surface on the evaporator of a refrigeration unit. Different

parameters were studied. The water flow rate was seen to inversely impact the

desalinated water production. The increase in air temperature increases the water

production. The HDH unit showed the same trends with all the packing materials

used. The use of cellulose paper led to the highest performance followed by the clay-

balls packing. Finally, the poorest performance was attained when saw-dust was used

as packing.

Key words: Humidification; Dehumidification; HDH; Packing Materials;

Refrigeration Unit.

Cite this Article: Hazem M. Saleh, Ehab M. Mina, Raouf N. Abdelmessih Effect of

Some Design and Operation Parameters on the Performance of A Water Desalination

Unit Using Humidification – Dehumidification. International Journal of Mechanical

Engineering and Technology, 8(5), 2017, pp. 681–693.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=5

1. INTRODUCTION

Fresh water is the key requirement for human presence on our planet. It is very important to

all activities of mankind. The lack of uncontaminated water causes the death of millions

annually (out of which 3900 infants [1]) either from famine, or from lack of sanitation. Future

wars are expected to be over water resources. Despite that earth is covered mainly by water,

fresh water represents only less than 3% [2]. In the light of this water sacristy, desalination

comes into the scene as the best solution to obtain fresh water. Several methods are used to

obtain fresh water. These methods are generally classified into membrane methods, and

thermal methods [3], [4].

Thermal methods such as multi-effect distillation (MED), multistage flash (MSF), and

vapor compression (VC) are the most known and widely used. These technologies were the

Effect of Some Design and Operation Parameters on the Performance of A Water Desalination Unit Using

Humidification – Dehumidification


interest of several researches in the past; these researches resulted in improved performance

that made them the main thermal technologies in the market.

Humidification dehumidification, HDH, is a modern technology that appeared in the

literature, in the last few decades. This method has the advantage of being suitable for Small

scale units. This advantage makes the HDH technology the subject of several investigations.

This method basically imitates the natural way of rain formation where air passes first over a

humidifier to gain water then it passes through a dehumidifier to reject this fresh water.

This Paper studies a humidification dehumidification cycle using an experimental setup to

investigate the effect of several parameters. The first parameter studied is the packing

material. Three different packings are used, namely: cellulose paper, fire clay balls, and saw

dust. The second factor studied is the temperature of inlet air. Air temperature is changed as

37, 65, and 90 ᵒC. Moreover, the effect of sprayed water temperature and quantity is tested.

The water temperatures used are: 27, 50, and 80 ᵒC. The water quantity varied from 150 m3/hr

to 600 m3/hr. This represents a water to air ratio of 8.88 to 14.48.

2. LITERATURE REVIEW

There are many previous papers that discussed this technology experimentally and

theoretically. The following paragraphs will review some of the recent works in this area.

Farid et. al [5]; constructed an HDH unit based on direct contact between air and solar

heated water. They found that the unit yielded 12 L/m2 of the collector which is 3 times the

production of a solar still. They found the best performance at water and air mass flow rates

of 80 and 50 kg/hr, respectively. At this ratio of 1.6 the GOR (called performance factor in

their paper) was 1.35.

Dai et. al [6]; constructed a solar HDH with a solar water collector. They found that the

perfect temperature range from 70 - 90 °C extracting fresh water from 30 to 105 (kg /hr).

They found that the GOR of the system is about 0.85 under optimal operating conditions.

Yamali et. al [7]; found that the productivity of the system increased with an increase of

feed water and air mass flow rates. They also found that the productivity of the system

increased with an increase in cooling water flow rate. Furthermore, they found that the

productivity of the system increased with an increase of initial water temperature.

Narayan et. al [8]; optimized the performance of HDH. They found that the varied

pressure systems have better performance than single pressure systems. Also, they found that

the air heated cycle is more efficient than even the water heated cycle. And they found that

the air heated cycles (GOR is roughly 2.5 times larger for the water heated case).

Farrag et.al [9]; used HDH unit with closed air open water. They found that efficient

contact between water and air will be accomplished by atomizing the hot saline water through

air stream. From the results, they found that the productivity of fresh water increases by

increasing air mass flow rate. Besides, the water productivity of the system increases with an

increase in the amount of water and inlet air temperatures. They calculated the GOR for the

system to be 4.2.

A. El-Haroun [10]; found that, using sponge as packing material will be better than

sawdust and clauses. Also, he found that, the productivity of the unit increased with the

enlargement in surface area of heat transfer of the humidifier. From the results, they also

found that the water productivity of the system decreases with an increase in the flow rate of

water.

Niroomand et. al [11]; found that increasing air flow rate has negative effect on the

production and energy consumption of the system. Also, they found that increasing the cold-



water flow rate will increase the water production. Also, by increasing the air flow rate the

amount of evaporation in the humidifier will increase. Additionally, by increasing the air flow

rate the amount of water production will decrease. They found that the optimum value of

water production is between 3 to 25 kg/hr.

Enaatollahi et. al [12]; found that, the water productivity of the system increases with an

increases in the inlet water temperature. Also, they found that the water production rate

initially increases with increasing air flow rate to an optimum value 1.7m3/sec, and beyond

that it decreases. In addition, they found that increases in the ambient air temperature increase

the desalinated water production up to an optimum value of 295 K, and beyond that a

reduction in the production was observed.

Khalil et. al [13];constructed an HDH unit. In humidifier, the air passes through the

orifices of a sieve plate at the bottom of a hot water pool to generate bubbles. They found that,

as inlet water temperature increases from 56.5 ᵒC to 62.2 ᵒC for air flow rate of 11 Kg/hr,

GOR values increases from 0.31 to 0.37. Furthermore, they found that as sieve hole's diameter

increased, the amount of extracting water decreased and a 5-mm orifice diameter gave the

check productivity. Increasing of air mass flow rate led to a slight increase in the amount of

extracted water.

Chehayeb et. al [14]; used a numerical model to simulate the operation of HDH at various

feed water flowrates. They compared between the performance of the single-stage system and

the two-stage system of the same size at different values of feed water. They found that, the

gain output ratio increases from 2.5 to 3.7. Also, they found that the two stage system results

in the highest GOR. Furthermore, they found the optimal water to air mass flow rate ratio

from 4.2 to 4.7.

J. S. Yassin [15]; found that the water productivity of the system increases with both the

increase in air to feed water mass ratio and with the increase of the air and water

temperatures. Also, they found that the water productivity of the system increase with an

increase the amount of water.

Table 1 shows a list of the packing materials used in HDH and Table 2 shows the range of

water to air mass ratio covered experimentally in several researches and it classifies their

findings according to the effect of mass ratio on the GOR. The last column titled comment

indicates whether increasing the mass ratio will increase or decrease. If an optimum was

found this is indicated and the optimum value is listed.

Table 1 Packing materials used in previous researches

Packing Type Author

Cellulose [16] , [17] , [18] , [19]

Ceramic Raschig Rings [20] , [21] , [22]

Wooden shaving [5] , [23] , [24]

Honey Comb Paper [6] , [25] ,[26]

Thorn Trees [27]

Canvas [28]

Wood covered with cotton textile [29]

Porous Plastic [30] , [31]

Plastic Rings [32]

Saw Dust [33]




Table 2 Effect of water flow rate on the unit performance

Reference m'w/m' air Optimum

Value GOR Comment

Farrag et al, [9] 0.1187 to 0.089 ---- 4.2 decrease

Narayan et al , [19] 1 to 7 ---- 2.6 - 4 increase

Thiel et al, [33] 1 to 3 ---- 4.84-5.65 increase

Kang et al, [34] 1.65 to 0.9 ---- 2.44 decrease

Khalil et al, [13] ---- ---- 0.53 ----

Hamed et al, [26] 0.000057 to 0.0266 ---- 1.85-2.1 Increase

Orfi et al, [29] 0.4 to 4 1.8 ----- Increase-then

decrease

3. SYSTEM DESCRIPTION

The current humidification–dehumidification desalination system consists of a blower, three

air heaters, humidifier, and two dehumidifiers. The first dehumidifier uses the incoming water

to cool the air the second is the evaporator of a 1/3 HP refrigeration unit. The system is based

on an open cycle for water and air stream. The unit is operated in a forced draft mode using

the blower. A packing material is used in to increase the mass transfer area in the humidifier

for efficient humidification of air. The saline water is pumped from saline water tank through

the dehumidifier tubes. Gaining sensible and latent heat of condensation of water vapor, the

saline water is preheated before entering the humidifier. In some experiments this water

passes through an auxiliary heater to reach a specified temperature before the humidifier. The

desalinated water is collected from the bottom of the dehumidifier, while the brine water is

rejected from the bottom of the humidifier. A schematic View of the experimental set up is

shown Fig (1) where three line types are used to illustrate the paths of air, water, and

refrigerant. Fig. (2) is a photograph of the setup to complement the description of the

experimental setup.



1 Compressor 2 Condenser

(refrigerant)

3 Cold Water

Pump

4 Saline Water

Tank

5 Dehumidifier I 6 Packing

Material

7 Humidifier 8 Electric Heaters 9 Blower

1 Humid Air 1 Hot Water Pump 1 Electric Water

Heater

1 Dehumidifier II 1 Desalinated Water

Tank

1 Expansion

device

Figure 1 A schematic View of the experimental set up Water desalination unit HDH




Figure 2 A photograph of the setup Water desalination unit HDH

4. RESULTS AND DISCUSSION

The experimental setup discussed in the previous section was used to perform experiments

using several packing materials. Also, an analytical estimation was implemented using EES.

Water temperature and water flow rates were recorded with and without the operation of

refrigeration cycle. The packing materials used were sawdust, clay balls and cellulose paper.

The water temperature introduced to the shower was 27 ᵒC, 50 ᵒC and 80 ᵒC. The temperature

of air was varied to be 37 ᵒC, 65 ᵒC and 90 ᵒC, using a set of heaters.

The water produced was plotted against time and the production rate was calculated at

steady state. The measured slope of the relation is the production rate. Figure 3 is an example

of the total production rate calculated in case of air at 27ᵒC, water at 50ᵒC at a rate of 300

L/hr, Clay balls as packing material, and with the operation of the refrigeration unit.

Results obtained were used to study the effect of four parameters on the performance of

the cycle. These parameters are the type of packing materials, the amount of water flow rate,

the temperature of water and the air flow rate. Each parameter is discussed in detail in the

remainder of this section.



Figure 3 Water production (L) with the time(min) as the experiment progress

4.1. Water to air mass ratio

Figure 4(a, b, and c) presents the effect of water to air mass ratio on the rate of production at

different air temperature for different packing materials. A general trend seen in the three

figures is that the desalinated water production rate decreases with the increase in the water to

air mass ratio. This inverse relation is almost linear. The production rate increases with the

increase in air temperature. This effect, of air temperature, is more pronounced at low

humidifier water flow rate (low mass ratios).

(A)

0

5

10

15

20

25

30

35

40

100 200 300 400 500 600

Pro

du

ctio

n r

ate

(L/

da

y)

Humidifier mass flowrate (L/hr)

TAir = 37 °C

TAir = 65 °C

TAir = 90 °C

Cellulose




(B )

(C )

Figure 4 Variation of the production rate of desalinated water with the flowrate of humidifier water

at different air temperatures a) for cellulose packing, b) for clay-balls packing, and c) for saw-dust

packing

4.2. Air temperature

To further discuss the effect of the air temperature, the variation of production rate (same

results of fig 4) are plotted against the air temperature in figure 5 for clay balls (as an

example). The graph shows the variation at all tested water flows. The results show the

positive impact of the air temperature on the production rate of potable water. The same trend

is witnessed with the other two packing materials.

0

5

10

15

20

25

30

35

40

100 200 300 400 500 600

Pro

du

ctio

n r

ate

(L/

da

y)


TAir = 37 °C

TAir = 65 °C

TAir = 90 °C

Clay balls

0

5

10

15

20

25

30

35

40

100 200 300 400 500 600

Pro

du

ctio

n r

ate

(L/

da

y)


TAir = 37 °C

TAir = 65 °C

TAir = 90 °C

Saw dust



Figure 5 Variation of water production with air temperature for a clay-balls packing at the extreem

water mass flow rate used

4.3. Packing material

Measurements clearly show that the cellulose packing is much superior than the other two

packing materials. The difference is more pronounced at high water mass flow rate, and low

temperatures. For example, at air temperature of 90 C and water flow of 150 L/hr: unit

production with cellulose, clay balls, and saw dust packings are 35 L/day, 28.8 L/day, and

21.1 L/day, respectively. While at air temperature of 37 °C and water flow rate of 600 L/hr

the production using the three packing are: 9, 9.6, and 7.2 L/day respectively. Figure 6 shows

samples of these variations. Figure 6 (a) shows the variation of water production with air

temperature for different packing materials at water flow of 150 L/hr, while Figure 6 (b)

shows the production variation with the water flux at 90 °C

(a)

5

10

15

20

25

30

25 35 45 55 65 75 85 95

Pro

du

ctio

n r

ate

L/d

ay

Air temperature °C

600 L/hr

450 L/hr

300 L/hr

150 L/hr

0

5

10

15

20

25

30

35

40

30 40 50 60 70 80 90 100

Pro

du

ctio

n r

ate

L/d

ay

Air temperature °C

Saw-dust

clay balls

cellulose




(b)

Figure 6 Comparizon between different humidifier packing material a) at different air temperature and

b) at different water mass flow rate

4.4. The operation of the refrigeration unit

As exiplained in the description of the setup, humid air passes over two consucative

condensing surfaces. The first is cooled by the feed water and the second is the evaporator of

a refrigeration unit. All the results displayed in the previous sections were obtained from

condensate collected from both surfaces. Due to the poor humidity content of the air leaving

the humidifier, the apparatus due point of the first condenser was not cold enough to

condensate water in some of the experiments. The operation of the refrigeration unit was key

to obtain most of the unit production of disalinated water because of the colder surface

temperature it provides. Figure 7 shows the produced desalinated rate with and without the

operation of the refrigeration unit at two different air temperatures (65°C and 90°C).

Figure 7 Effect of operation of the air conditioning unit on the production rate at different air

temperatures

0

5

10

15

20

25

30

35

40

100 200 300 400 500 600

Wa

ter

pro

du

ctio

n L

/da

y

water flow rate L/hr

Saw-dust

clay balls

cellulose

0

5

10

15

20

25

30

35

40

100 200 300 400 500 600

Wa

ter

pro

du

ctio

n (

L/d

ay

)

Humidifier water flow rate (L/hr)

Tair=65 C Refrigeration unit OFF Tair=90 C Refrigeration unit OFF

Tair=65 C Refrigeration unit ON Tair=90 C Refrigeration unit ON



6. CONCLUSION

This paper studied experimentally the performance of a desalination unit with refrigeration

unit integrated to enhance its production. Several design and operational parameters were

investigated. It is concluded that the production of desalinated water is inversely related to the

amount of water sprayed in the humidifier. The increase in the air temperature at the inlet of

the humidifier increases the water production. Cellulose paper proved to be superior to the

clay balls and saw dust as a packing material in such applications. Finally, the operation of the

refrigeration unit was essential to the production of desalinated water from the current setup.

For future work, we recommend redesigning the humidification tower to better humidify

the air. Besides, the refrigeration unit could be better integrated to the unit so that the

condenser is subjected to the inlet air to serve in heat addition. Moreover, this unit could be

integrated to large Air conditioning systems to condition the fresh air supply and obtain

desalinated water along with the cold dry fresh air.

REFERENCES

[1] M. Montgomery and M. Elimelech, “Water and sanitation in developing countries:

including health in the equation,” Environ. Sci. Technol., vol. 41, no.1, pp.17-24, 2007.

[2] W. Abdelmoez, M. S. Mahmoud, and T. E. Farrag, “Water desalination using

humidification / dehumidification (HDH) technique powered by solar energy: a detailed

review,” Desalin. Water Treat., vol. 52, no.25-27, pp.4622-4640, 2013.

[3] Y.B. Karhe and P. V. Walke, “A solar desalination system using humidification –

dehumidification process – A review of recent research,” IJMER, vol. 3, no.2, pp.962-969,

2013.

[4] S. Parekh, M. Farid, J. R. Selman, and S. AL-Hallaj, “Solar desalination with a

humidification – dehumidification technique – A comprehensive technical review,”

Desalination, vol. 160, pp.167-186, 2004.

[5] M. Farid, and A. W. AL-Hallaj, “Solar desalination with a humidification –

dehumidification cycle,” Desalination, vol. 106, no.1-3, pp.427-429, 1996.

[6] Y. J. Dai, and H. F. Zhang, “Experimental investigation of a solar desalination unit with

humidification and dehumidification,” Desalination, vol. 130, pp.169-175, 2000.

[7] C. Yamali, and I. Solmus, “A solar desalination system using humidification –

dehumidification process: experimental study and comparison with the theoretical

results,” Desalination, vol. 220, no.1-3, pp.538-551, 2008.

[8] G. P. Narayan, M. H. Sharqawy, John H. L. V. and S. M. Zubair, “Thermodynamics

analysis of humidification dehumidification desalination cycles,” Desalination, vol. 1078,

no.c, 2010.

[9] T. E. Farrag, M. S. Mahmoud and W. Abdelmoez, “Experimental validation for two

stages humidification – dehumidification (HDH) water desalination unit,” IWTC 17, pp.1-

16, 2013.

[10] A. A. El-Haroun, “Desalination system with humidification – dehumidification of air,”

Int. J. Pure Appl. Sci. Technol., vol. 14, no.1, pp.44-52, 2013.

[11] N. A. Niroomand, M. Zamen, and M. Amidpour, “Theoretical investigation of using a

direct contact dehumidifier in humidification – dehumidification desalination unit based

on an open air cycle,” Desalin. Water Treat., no.1, pp.1-11, 2014.

[12] R. Enayatollahi, T. Anderson, and R. Nates, “Mathematical modeling of a solar powered

humidification dehumidification desalination prototype,” The 52nd Annual Conference of

the Australian solar Council, 2014.

[13] A. Khalil, S. A. El-Agouz, Y. A. F. El-Samadony and A. I. Abdo, “Solar bubble

humidification – dehumidification desalination unit,” IWTC18, 2015.




[14] K. M. Chehayeb, and J. H. Lienhard V., “Effect of feed salinity on the performance of

humidification dehumidification desalination,” IDAWC, 2015.

[15] J. S. Yassin, “Performance evaluation of a solar humidification – dehumidification

desalination unit,” IJEIT, vol. 1, no.2, pp.15-22, 2015.

[16] E. Chafik, “A new type of seawater desalination plants using solar energy,” Desalination,

vol. 156, pp.333-348, 2003.

[17] E. Chafik, “Design of plants for solar desalination using the multi-stage heating /

humidifying technique,” Desalination, vol. 168, pp.55-71, 2004.

[18] G. Franchini, L. E. Padovan, and A. Perdichizzi, “Design and construction of a

desalination prototype based on HD (Humidification – Dehumidification) process,”

Energy Procedia, vol. 81, pp.472-481, 2015.

[19] G. Prakash Narayan, M. G. St. John, S. M. Zubair, and J. H. Lienhard, “Thermal design of

the humidification dehumidification desalination system: An experimental investigation,”

Int. J. Heat Mass Transf., vol. 58, no.1-2, pp.740-748, 2013.

[20] M. Khedr, “Techno-Economic investigation of an air humidification – dehumidification

desalination process,” Chem. Eng. Technol., vol. 16, no.4, pp.270-274, 1993.

[21] A. A. Shabaneh, P. Gandhidasan, M. A. Antar, and H. Baig, “Simulation of HDH

desalination system using tilted two-pass solar air heater,” IWTC15, 2011.

[22] A. E. Kabeel, T. A. Elmaaty, and E. M. S. El-Said, “Economic analysis of a small-scale

hybrid air HDH-SSF (humidification and dehumidification-water flashing evaporation)

desalination plant,” Energy., vol. 53, pp.306-311, 2013.

[23] M. M. Farid, S. Parekhb, J. R. Selmanb, and S. Al-Hallajb, “Solar desalination with a

humidification – dehumidification mathematical modeling of the unit cycle,”


[24] N. Kh. Nawayseh, M. M. Farid, Said Al-Hallaj, and A. R. Al-Timimi, “Solar desalination

based on humidification process – I. Evaluating the heat and mass transfer coefficients,”

Energy conversion & Management, vol. 40, pp.1423-1439, 1999.

[25] Y. J. Dai, R. Z. Wang, and H. F. Zhang, “Parametric analysis to improve the performance

of a solar desalination unit with humidification and dehumidification,” Desalination, vol.

142, no.2, pp.107-118, 2002.

[26] M. H. Hamed, A. E. Kabeel, Z. M. Omara, and S. W. Sharshir, “Mathematical and

experimental investigation of a solar humidification – dehumidification desalination unit,”


[27] H. Ben Bacha, T. E. Damak, M. Bouzuenda, and A. Y. Maalej, “Experimental validation

of the distillation module of a desalination state using the SMCEC principle,” Renew.

Energy, vol. 28, no.15, pp.2335-2354, 2003.

[28] A. S. Nafey, “Solar desalination using humidification – dehumidification part II. An

experimental investigation,” Energy conversion & Management, vol. 45, pp.1263-1277,

2004.

[29] J. Orfi, M. Laplante, H. Marmouch, N. Galanis, and B. Benhamou, S. Ben Nasrallah, and

C. T. Nguyen, “Experimental and theoretical study of a humidification – dehumidification

water desalination system using solar energy,” Desalination, vol. 168, pp.151-159, 2004.

[30] A. E. Kabeel, Emad M. S. El-said, “A hybrid solar desalination system of air

humidification dehumidification and water flashing evaporation part I. A numerical

investigation,” IWTC16, pp.1-35, 2012.

[31] Ghazi Al-Enezi, Hisham Ettouney, Nagla F., “Low temperature humidification

dehumidification desalination process,” Energy conversion & Management, vol. 47,

pp.470-484, 2006.

[32] M. Mehrgoo, and M. Amidpour, “Constructal design of humidification – dehumidification

desalination unit architecture,” Desalination, vol. 271, pp.62-71, 2011.



[33] G. P. Thiel, J. a. Miller, S. M. Zubair, and J. H. Lienhard, “Effect of mass extractions and

injections on the performance of a fixed – size humidification – dehumidification

desalination system,” Desalination, vol. 314, pp.50-58, 2013.

[34] Abdelhakim Hassaboua, Markus Spinnlerb And Wolfgang Polifkeb The Role Of

Conductive Packing In Direct Contact Humidification-Dehumidification Regenerators -

Part I: Theoretical Analysis. International Journal of Mechanical Engineering and

Technology, 5(12), 2015, pp.126-138.

[35] H. Kang, Y. Yang, Z. Chang, H. Zheng, and Z. Duan, “Performance of a two – stage

multi-effect desalination system based on humidification – dehumidification process,”


effect of some design and operation ......cite this article: hazem m. saleh, ehab m. mina, raouf n....

Documents