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Institute for Thermodynamics and Thermal Engineering

University of Stuttgart

Performance of CQM's SRS System

Subjected To Severe Crystallization Fouling of

CaSO4 Institute for Thermodynamics and Thermal Engineering (ITW) Prof. Dr.-Ing. habil. Hans Müller-Steinhagen Dr.-Ing. Mohammad Reza Malayeri University of Stuttgart Pfaffenwaldring 6 70550 Stuttgart, Germany Tel +49 (0) 711/685-63536 Fax +49 (0) 711/685-63503

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About the Institute for Thermodynamics and Thermal Engineering (ITW): The Institute for Thermodynamics and Thermal Engineering (ITW), University of Stuttgart was founded in 1962 and later by Prof. Dr.-Ing. Emil Theodor Schmidt (1962-1973) and Prof. Dr.-Ing. Erich Hahne (1973-2000) directed. Since April 2000, the Institute headed by Prof. Dr.-Ing. habil. Hans Müller-Steinhagen. For many years, the Institute has focused its research activities on the two areas of advanced heat transfer processes and solar thermal systems for domestic applications. At present, the institute employs 35 staff out of which 25 are research scientists and engineers. Senior staff of ITW have been involved in fouling research since 1980 and have published more than 200 papers and several books on fouling fundamentals and mitigation. They have been organising and chairing the bi-yearly International Fouling Conferences since 2001 and been involved in numerous research and consultancy projects with industry. The second line of research of ITW is in the area of solar thermal water and space heating, where it operates Europe´s largest research and testing centre for solar thermal collector and heat storage systems. The Institute for Thermodynamics and Thermal Engineering has extensive laboratory infrastructure with modern instrumentation and equipment. Through a joined directorship it is closely linked to the Institute of Technical Thermodynamics of the German Aerospace Centre, which is located on the same campus in Stuttgart. April, 2008 Dear Mr. Livni, Please find attached the report on the performance of SRS system subjected to severe crystallization fouling of CaSO4. The report is rather comprehensive and a result of 6 months intensive full experiment at ITW. Report Conclusions: The test results show that the SRS water treatment significantly reduces the water's CaSO4 propensity for crystallization in roughened stainless steel surfaces, reducing fouling resistance as a function of time by up to 95% depending on the surface's roughness.

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1. The SRS System CQM SRS – Water Treatment System is a chemical-free solution for removing scale and for elimination of algae and bacteria to keep water circuits clean.

How it Works CQM SRS uses the electrolytic process, implementing a large cathode area that creates a high PH environment that encourages scale formation inside the device. A hydro cyclone structure ensures that all the water within the chamber is treated. The water flows through the electrolytic chamber and functions as a medium that closes the electric cycle enabling the DC current to flow between the anode and cathode of the system. Two disinfecting processes occur on the surface of the anode (+): v Anode oxidation reaction v Acidic catalytic reaction

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Chemical Reactions at Work in the SRS The anode oxidation reaction is a series of reactions that produce gases and free radicals with high oxidation potential that disinfects the water. Electrolysis works as follows: v Water in the cycle is pumped into the electrolysis chamber. v The water pH level is raised slightly increasing the alkaline environment

and preventing corrosive processes. v Free chlorine is produced which helps to destroy bacteria. v Higher pH causes corrosion to aggregate into suspended solids that can be

removed with a sand filter. As a result of the basic pH conditions on the cathode surface the following reactions occur: Mg(HCO3)2+4OH-→Mg(OH) 2↓+2H2O+2CO3-² Ca(HCO3)2+2OH-→ CaCO3↓+2H2O + CO3-² Mg(HCO3)2→MgCO3↓+2H2O + CO2↑ (SiO2)aq →SiO2)↓ The main ingredients of scale in water systems (MgCO3, CaCO3, Mg(OH)2, SiO2) are almost completely removed from the water in this process. The following reactions occur on the face of the anodes: OH- - e→OH° Radical OH° OH° →H2O + O° Radical Oxygen 2OH° →H2O2 Peroxide Cl- - e→Cl° Radical chlorine 2Cl° → Cl2 Molecular chlorine In addition, this process produces Active Chloride that works to purify the water naturally, without harmful chemical additives.

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2. Test Results

Fig. 1 Variation of fouling resistance with time as a function of SRS system of 0.55 μm roughened surface

Fig. 2 Variation of fouling resistance with time as a function of SRS system of 0.955 μm

roughened surface

0 50 100 150 200-5.0x10-5

0.0

5.0x10-5

1.0x10-4

1.5x10-4

2.0x10-4

2.5x10-4

3.0x10-4

3.5x10-4

4.0x10-4

q. = 120 kWm2

v= 0.27 m/sc

b = 3.5 g/L

Ts= 63oCR

a = 0.55 µm

ISRS

= 5 Amp

Bulk

tem

prea

ture

effe

ct

Rf,

m2 K

W-1

time, min

dRf/dt= 2.5e-6 m2K W-1min-1

tind = 100 minR

ough

ness

per

iod

indution period

SRS-effect

0 20 40 60 80 100 120 140 160-5.0x10-5

0.0

5.0x10-5

1.0x10-4

1.5x10-4

2.0x10-4

2.5x10-4

q. = 120 kWm2

v= 0.27 m/sc

b = 3.5 g/L

Ts= 63oC

Ra = 0.955 µm

ISRS

= 5 Amp

tind

= 60 min

indution period

SRS-effect

Bulk

tem

prea

ture

effe

ct

Rou

ghne

ss p

erio

d

dRf/dt= 1.31e-6 m2K W-1min-1

time, min

Rf,

m2 K

W-1

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Fig. 3 Variation of fouling resistance with time as a function of SRS system of 1.35 μm roughened surface

Fig. 4 Variation of bulk temperature with time

0 20 40 60 80 100 120 140 160-5.0x10-5

0.0

5.0x10-5

1.0x10-4

1.5x10-4

2.0x10-4

2.5x10-4

SRS-effect

tind

= 60 min

indution period

Rou

ghne

ss p

erio

d

Bulk

tem

prea

ture

effe

ct

dRf/dt= 1.51e-6 m2K W-1min-1

Rf, m

2 K W

-1

time, min

q. = 120 kWm2

v= 0.27 m/scb = 3.5 g/L

Ts= 63oCR

a = 1.35 µm

ISRS

= 5 Amp

0 25 50 75 100 125 15010

20

30

40

50

60

70q. = 120 kWm2

v= 0.27 m/sISRS

= 5 Amp

bulk

tem

pera

ture

,o C

time, min

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Fig. 5 Variation of bulk velocity with time

Fig. 6 Fouling resistance as a function of time of 0.54 μm roughened stainless steel

surfaces with and without SRS

0 50 100 1500.05

0.10

0.15

0.20

0.25

0.30

q. = 120 kWm2

v= 0.27 m/sISRS

= 5 Amp

flow

rate

, l/s

time, min

0 50 100 150 200 250

0.0000

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

dRf/dt= 4.25e-6 m2K W-1min-1

time, min

dRf/dt= 1.31e-6 m2K W -1min-1

Rf, m

2 K W

-1

q. = 120 kWm2

Ra = 0.55 µm

without SRS with SRS

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Fig.7 Fouling layer of stainless steel roughened surfaces at q. = 120 kW/m2, v = 0.27 m/s,

and ISRS = 5 Amp

1.35 μm

0.55 μm

0.95 μm

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Fig. 8 Variation of fouling resistance with time as a function of SRS system of 0.54 μm roughened surface

Fig. 9 Variation of fouling resistance with time as a function of SRS system of 1.1 μm roughened surface

0 200 400 600 800 1000 1200

0.0

1.0x10-5

2.0x10-5

3.0x10-5

4.0x10-5

tind

= 126 min dRf/dt= 2.11e-8 m2K W-1min-1

time, min

Rf,

m2 K

W-1

q. = 120 kWm2

v= 0.15 m/sc

b = 3.6 g/L

Ts= 75oC

Ra = 1.05 µm

ISRS

= 5 Amp

0 100 200 300 400 500

0.0

2.0x10-5

4.0x10-5

6.0x10-5

8.0x10-5

tind

= 153 min

dRf/dt= 2.95e-7 m2K W-1min-1

time, min

Rf, m

2 K W

-1q. = 120 kWm2

v= 0.15 m/sc

b = 3.5 g/L

Ts= 82.5oC

Ra = 0.56 µm

ISRS

= 5Amp

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Fig. 10 Fouling resistance as a function of time of 0.54 μm roughened stainless steel

surfaces with and without SRS

Fig. 11 Fouling resistance as a function of time of 1.1 μm roughened stainless steel

surfaces with and without SRS

0 100 200 300 400 500 600 700

0.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

dRf/dt= 2.5e-6 m2K W-1min-1

Rf, m

2 K W

-1

q. = 120 kWm2

v= 0.15 m/sT

s= 82oC

Ra = 0.54 µm

time, min

dRf/dt= 2.95e-7 m2K W-1min-1

with SRS, 5Amp without SRS

0 200 400 600 800 1000 1200 1400-1.0x10-4

0.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

7.0x10-4 with SRS, 5 Amp without SRS

Rf,

m2 K

W-1

time, min

dRf/dt= 1.02e-6 m2K W-1min-1

dRf/dt= 2.11e-8 m2K W-1min-1

q. = 120 kWm2

v= 0.15 m/sTs= 75oCR

a = 1.1 µm

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Fig. 12 Fouling layer of stainless steel roughened surfaces a) without SRS and b) with SRS at q. = 120 kW/m2, v = 0.15 m/s, and ISRS = 5 Amp

Ra= 0.56 μm, Ts = 82oC

a) without SRS b) with SRS

Ra= 1.05 μm, Ts = 75oC

Ra= 0.54 μm, Ts = 82oC

Ra= 1.1 μm, Ts = 75oC

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Fig. 13 Fouling resistance as a function of time of 0.54 μm roughened stainless steel

surfaces at 5 and 10 Amp

Fig. 14 Fouling resistance as a function of time of 1.55 μm roughened stainless steel

surfaces at 5 and 10 Amp

0 50 100 150 200 250 300 350 400

0.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

time, min

Rf,

m2 K

W-1

tind

= 45 min

dRf/dt= 6.21e-6 m2K W-1min-1

tind = 180 min

dRf/dt= 4.78e-6 m2K W-1min-1

q. = 120 kWm2

v= 0.15 m/sc

b = 4 g/L

Ts= 84oC

ISRS

= 5 Amp I

SRS = 10 Amp

0 50 100 150 200 250 300 350 400

0.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

time, min

Rf,

m2 K

W-1

ISRS = 5 Amp I

SRS = 10 Amp

q. = 120 kWm2

v= 0.15 m/scb = 4 g/L

Ts= 84oC

tind = 115 min

dRf/dt= 4.78e-6 m2K W-1min-1

tind

= 30 min

dRf/dt= 8.51e-6 m2K W-1min-1