CFD optimization of photochemical UV reactors for VOC degradation

(1)

CFD optimization of photochemical

UV reactors for VOC degradation

Anna Andersson

Sustainable Process Engineering, master's level

2017

Luleå University of Technology

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

V̇



(12)

       

(13)

(14)

(15)

(16)

(17)

(18)

(19)

𝑂3+ ℎ𝑣 (243 − 310 𝑛𝑚) → 𝑂(1𝐷)+ 𝑂2

𝑂2+ ℎ𝑣 (< 243 𝑛𝑚) → 𝑂(1𝐷)+ 𝑂(3𝑃)

(20)

 𝑂𝐻+ 𝑃 → 𝑃+ 𝐻2𝑂 𝑃+ 𝑂2→ 𝐶𝑂2+ 𝐻2𝑂 𝑂𝐻+ 𝑝𝑜𝑙𝑙𝑢𝑡𝑎𝑛𝑡 + 𝑂2 → 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑠 (𝐶𝑂2, 𝐻2𝑂 𝑒𝑡𝑐. ) 𝑂(1_𝐷)_{+ 𝐻} 2𝑂 → 2𝑂𝐻   

(21)

(22)

𝑇𝑖𝑂2+ ℎ𝑣 → ℎ++ 𝑒− ℎ+_{+ 𝑂𝐻}−_{→ 𝑂𝐻} ℎ+_{+ 𝐻} 2𝑂 → 𝑂𝐻+ 𝐻+ 𝑂3+ 𝑒−→ 𝑂3 − 𝐻++ 𝑂3 −→ 𝐻𝑂3 𝐻𝑂3 → 𝑂2+ 𝑂𝐻

(23)

(24)

(25)

 

(26)

𝑂2+ ℎ𝑣 (< 243 𝑛𝑚) → 𝑂(1𝐷)+ 𝑂(3𝑃)

𝑂(1_𝐷)_{+ M → 𝑂(}3_𝑃)_{+ 𝑀}

𝑂(3_𝑃)_{+ 𝑀 + 𝑂}

(27)

(28)

(29)

V̇ 

(30)

𝑝2_{= (𝐻 − ℎ)}2_{+ 𝑥}2 1 (𝑝2₎ 𝑑(𝑝2_𝐼) 𝑑𝑝 = −𝜎𝐼 

(31)

𝐼 = 𝐼𝑠 𝑑ℎ 4 𝜋 𝑝2𝑒−𝜎𝑝 𝐼𝐸= 𝐼𝑠 𝑑ℎ 4 𝜋 𝑝2 𝐼𝐸= ∫ 𝑃_{𝑙𝑎𝑚𝑝} 𝐸𝑓𝑓_{𝑖𝑟𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛} 𝑑ℎ 4 𝜋 (𝑥2_{+(𝐻−ℎ)}2₎ 𝐿/2 −𝐿/2 = 𝑃_{𝑙𝑎𝑚𝑝} 𝐸𝑓𝑓_{𝑖𝑟𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛} 4 𝜋 ∫ 1 (𝑥2_{+(𝐻−ℎ)}2₎ 𝑑ℎ 𝐿/2 −𝐿/2 𝐼𝐸= 𝑃_{𝑙𝑎𝑚𝑝} 𝐸𝑓𝑓_{𝑖𝑟𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛} 4 𝜋 𝐿 𝑥 [arctan ( 𝐿/2+𝐻 𝑥 ) + arctan ( 𝐿/2−𝐻 𝑥 )] 𝐼𝑇 185 𝑛𝑚= 𝐼𝐸 𝑒−𝜎𝑂2 𝐶𝑂2 𝑥 σO2 CO2=

Absair (absorption air)

(32)

𝐼𝑇 254 𝑛𝑚= 𝐼𝐸 𝑒−𝜎𝑂3 𝐶𝑂3 𝑥 𝐼𝑇 = ∫ ( 𝑃_{𝑙𝑎𝑚𝑝} 4 𝜋 𝐿 [( 1 𝐻+𝐿₂) 2 + 𝑥2− (𝐿1 2−𝐻 ) 2 + 𝑥2] 𝑒 −𝐴𝑏𝑠𝐴𝑖𝑟 √( 1 𝐻+𝐿₂) 2 +𝑥2₋₍ 1 𝐿 2−𝐻 ) 2 +𝑥2 ) 𝐻 𝑚𝑎𝑥 𝐻 𝑚𝑖𝑛 𝐼𝑇 185 𝑛𝑚= 𝐼𝐸 𝑒−𝐴𝑏𝑠𝑎𝑖𝑟 𝑥 𝑘𝑠𝑖𝑧𝑒 𝐼𝑇 254 𝑛𝑚= 𝐼𝐸 𝑒−𝜎 𝐶𝑂3 𝑥 𝑘𝑠𝑖𝑧𝑒

(33)

𝑂3 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑖𝑜𝑛= 2 𝐴𝑏𝑠𝑝ℎ𝑜𝑡𝑜𝑛 𝑁𝐴 𝐴𝑏𝑠𝑝ℎ𝑜𝑡𝑜𝑛= 𝐴𝑏𝑠185 𝐸𝑛185 𝐴𝑏𝑠185= 𝐼𝐸− 𝐼𝑇 185 𝑛𝑚 𝑅𝑂3 𝑑𝑒𝑐 [𝑂𝐻] 𝑅𝑉𝑂𝐶 𝑑𝑒𝑐 𝑅𝑉𝑂𝐶 𝑑𝑒𝑐 = 𝑘𝑝𝑎𝑟 [𝑉𝑂𝐶] [𝑂𝐻] = 𝑘𝑝𝑎𝑟 [𝑉𝑂𝐶] 𝑅𝑂3 𝑑𝑒𝑐

(34)

𝑅𝑂3 𝑑𝑒𝑐 𝐼𝐸− 𝐼𝑇 254 𝑛𝑚 𝑅𝑂3 𝑑𝑒𝑐 𝐼𝐸− 𝐼𝐸 𝑒−𝜎 𝐶𝑂3 𝑥 𝑘𝑠𝑖𝑧𝑒 = 𝐼𝐸 (1 − 𝑒−𝜎 𝐶𝑂3 𝑥 𝑘𝑠𝑖𝑧𝑒) 𝑅𝑉𝑂𝐶 𝑑𝑒𝑐 = 𝑘𝑝𝑎𝑟 [𝑉𝑂𝐶] (𝐼𝐸 (1 − 𝑒−𝜎 𝐶𝑂3 𝑥))



  

(35)

𝜌(𝑈 ∙ ∇𝑈) + ∇ ∙ (𝜇𝑇(∇𝑈 + (∇𝑈)𝑇) −2₃𝜇𝑇(∇ ∙ 𝑈)𝐼) = −∇𝑃 + ∇ ∙ (𝜇(∇𝑈 + (∇𝑈)𝑇) −2₃𝜇(∇ ∙ 𝑈)𝐼) + 𝐹     ∇ ∙ 𝑈 = 0 𝜕𝐶𝑖 𝜕𝑡 + ∇ ∙ 𝑁𝑖 = 𝑅𝑖

(36)

∂Ci ∂t

(37)

(38)

(39)

(40)

   

(41)

(42)

(43)

(44)

0% 20% 40% 60% 80% 100% 5 cm 6 cm 8 cm 9 cm 10 cm 12 cm 14 cm 16 cm 18 cm 20 cm Con ve rs ion Lamp distance

Conversion for lamp distance trials

COMSOL results Normalized results

(45)

0% 20% 40% 60% 80% 100% 3 4e 5 6 7 8 9 N o rm aliz ed con ve rs ion Case number

(46)

(47)

(48)

(49)

(50)

0% 20% 40% 60% 80% 100% 120% 140% 1 10a 10b 4e 11a 11b 11c N o rm aliz ed con ve rs ion Case number

(51)

(52)

0% 20% 40% 60% 80% 100% 120% A1 A2 B1 B2 C N o rm aliz ed con ve rs ion Case number

(53)

0% 20% 40% 60% 80% 100% 120% A1 D B1 E C F1 F2 N o rm aliz ed con ve rs ion Case number

(54)

(55)

0% 20% 40% 60% 80% 100% A1 G H I J N o rm aliz ed con ve rs ion Case number

(56)

0% 20% 40% 60% 80% 100% 120% 140% 160% C K L M N o rm aliz ed con ve rs ion Case number

(57)

(58)

(59)

(60)

(61)

 o   o o o o o

(62)

(63)

(64)

(65)

(66)

(67)

(68)

(69)