Experimental and Numerical Analysis of a PCM-Supported ...

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m Mass flow rate; [kg.s -1 ] m evap Evaporation rate; [mol.s -1 ] m cond Condensation rate; [mol.s -1 ] N Evaporative mass flux; [mol.m -2 .s -1 ] n Evaporative mass flux; [mol.m -2 .s -1 ] Nu Nusselt number, dimensionless [= h L st /k] NTU Number of transfer units P& p Pressure; [N.m -2 ] Pr Prandtl number; dimensionless [μC p /k] Pe Péclet number; dimensionless Q Amount of heat transfer; [J] Q Heat flow; [W] q" Heat flux; [W.m -2 ] R universal gas constant; [8.314 J.mol -1 .K -1 ] r c Brine concentration factor; dimensionless Re Reynolds number; dimensionless [v D/ ν] Re o Superficial Reynolds number; dimensionless [= V d/ ν] Sh Sherwood number; dimensionless [= K L st /D] S Saturation S Shape factor Ste Stefan number, dimensionless T Temperature; [K] T a Ambient temperature; [K] T g_in Inlet gas temperature (evaporator or condenser); [K] T g_out Outlet gas temperature (evaporator or condenser); [K] T a1 Bottom air temperature; [K] T a2 Top air temperature; [K] T l_in Inlet water temperature (evaporator or condenser); [K] T l_out Outlet water temperature (evaporator or condenser); [K] T w1 Outlet brine water temperature from the evaporator; [K] T w2 Inlet hot water temperature to the evaporator; [K] T w3 Inlet cooling water temperature to the condenser; [K] T w4 Outlet cooling water temperature from the condenser; [K] T m Melting temperature; [K] T pcm1 Surface (wall) temperature of phase change material cell; [K] T 1 Initial temperature; [K] T 2 Final temperature; [K] t Time; [sec] ΔP Pressure drop ; [N.m -2 ] ΔT Temperature difference; [K] ΔT m , ΔT t Half width of melting temperatures range; [K] ΔT LM Logarithmic mean temperatures difference; [-] xiv
U Overall heat transfer coefficient between gas and liquid; [W.m -2 . K -1 ] U 0 Superficial velocity; [m.s -1 ] u, v Mean axial velocity in the packed bed; [m.s -1 ] v p Average pore velocity of the fluid (bulk mean velocity); [m.s -1 ] u D Darcian velocity of the fluid; [m.s -1 ] V Superficial velocity; [m.s -1 ] V Volume; [m 3 ] v Velocity; [m. s -1 ] v sup Superficial velocity; m.s -1 ] w Mass fraction of water vapor in air or absolute humidity ratio; [kg/kg air] y Mol fraction of water vapor in gas mixture Z Coordinate of the axial direction or packing height; [m] Greek Letter Symbols α Thermal diffusivity; [m 2 .s -1 ] β t Volumetric thermal expansion coefficient; [K −1 ] β c Volumetric diffusion expansion coefficient; [m 3 .mol −1 ] θ Phase fraction θ Relative humidity [%] μ Dynamic viscosity; [N . s.m -2 ] ν Kinematic viscosity; [m 2 .s -1 ] ρ Density; [kg .m -3 ] η Time; [s] ε Porosity, dimensionless ε l Liquid holdup, liquid fraction in a unit volume of packed column ε g Gas holdup, gas fraction in a unit volume of packed column ε s Solid fraction in a unit volume of packed column ζ Surface tension; [J .m -2 ] δ Liquid film thickness, [m] ψ Relative humidity; [%] ψ Accumulation parameter; dimensionless δ Liquid film thickness; [m] η Efficiency ζ Effectiveness Subscripts a act atm amb ball Air Actual Atmospheric Ambient The packing sphere or ball xv
Page 1: Technische Universität München In
Page 4 and 5: It is my pleasure to thank Prof. Th
Page 6 and 7: Contents List of figures ..........
Page 8 and 9: 5.3 Functional description ........
Page 10 and 11: List of Figures Figure 1.1: Cost br
Page 12 and 13: 78cm; Top: Evaporator, Bottom: Cond
Page 14 and 15: xii
Page 18 and 19: ed c coll cond cw d d e or eff evap
Page 20 and 21: 1 Introduction The first part of th
Page 22 and 23: summarized in figure (1.2). Thermal
Page 24 and 25: 1.3.2 Selection criteria of desalin
Page 26 and 27: of energy storage or hybridization
Page 28 and 29: Desalination development focuses on
Page 30 and 31: Introduction of the indirect type s
Page 32 and 33: 2 Literature Survey 2.1 Introductio
Page 34 and 35: There is actually a commercial prod
Page 36 and 37: Q m H c ( T T1) c ( T 2 T ) (2.2)
Page 38 and 39: (solid-liquid) have a storage densi
Page 40 and 41: (iii) a sharp melting temperature.
Page 42 and 43: melt and freeze without segregation
Page 44 and 45: However, the stored heat is less va
Page 46 and 47: parameters on the heat transfer and
Page 48 and 49: categories. The first category is b
Page 50 and 51: to 550 kWh/m 3 of distilled water a
Page 52 and 53: The enthalpy and humidity of the sa
Page 54 and 55: Air mass flow rate [kg/h] GOR [-] 1
Page 56 and 57: On the other hand, the efficiency o
Page 58 and 59: 2.8.4.2 Effect of air to water mass
Page 60 and 61: distillate rate. The system was not
Page 62 and 63: were; EnviPac Gr.1, 32 mm, and VFF
Page 64 and 65: Figure 2.15: Height versus air temp
Page 66 and 67:
The performance of the condenser is
Page 68 and 69:
Klausner and Mei [136] described a
Page 70 and 71:
The impact of the collector cost ca
Page 72 and 73:
exchanger and energy storage in one
Page 74 and 75:
3 Scope of the Study This chapter p
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packing where it gets in direct con
Page 78 and 79:
In fact there is a tradeoff between
Page 80 and 81:
The energy flow between all and eac
Page 82 and 83:
4 Theoretical Analysis and Modeling
Page 84 and 85:
The two-energy equation models whic
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solid-liquid phase change inside th
Page 88 and 89:
assumed by conduction in both axial
Page 90 and 91:
the air pressure drop ∆P per unit
Page 92 and 93:
evaporation rate per unit volume of
Page 94 and 95:
where β t , β c , ρ ref , c ref
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the viscous transport and introduce
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liquid and solid phases, respective
Page 100 and 101:
4.2.3.3 Liquid and gas hold-ups Liq
Page 102 and 103:
Several models and approaches for m
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where G=ρU d /ε g is the pore mas
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k k eff s 1 3 2 (4.55) This cor
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uncertainties associated with the f
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1 2 (4.62) d1 capp c2 c1 c2 1
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[58] evaluated the cooling tower ai
Page 114 and 115:
1 exp NTU 1 C r, cond cond (4
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A HE QHE U T HE LM (4.81) Where Q
Page 118 and 119:
c M f b (4.86) M b S S f where r
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that form the study logical foundat
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5 Experimental Analysis This chapte
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5.2 Measuring Techniques K-type the
Page 126 and 127:
The product condensed water was mea
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operating limits. In light of the l
Page 130 and 131:
In the last two cases, the inlet ho
Page 132 and 133:
performance and its threshold value
Page 134 and 135:
It could be interpreted that this p
Page 136 and 137:
Evaporator Condenser Figure 5.8: Av
Page 138 and 139:
within the inaccuracy margins. The
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The last two cases of boundary cond
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natural air flow in the system. In
Page 144 and 145:
6 Model Implementation and Validati
Page 146 and 147:
x t u x u 0 0 , (6.5) and for a s
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Next time step validation were the
Page 150 and 151:
The evaporator and condenser both w
Page 152 and 153:
Figure 6.2: Evolution of inlet and
Page 154 and 155:
Figure 6.4: Evolution of inlet and
Page 156 and 157:
temperature is at its maximum level
Page 158 and 159:
Bottom Top Figure 6.7: Evolution of
Page 160 and 161:
7 Parameters Analysis of the Evapor
Page 162 and 163:
Figure 7.1: Effect of packing size
Page 164 and 165:
e 0.45 kPa under natural convection
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aspect ratio under constant bed vol
Page 168 and 169:
Figure 7.7: Effect of inlet hot wat
Page 170 and 171:
well as the time required to reach
Page 172 and 173:
Figure 7.10: Effect of packing medi
Page 174 and 175:
40°C respectively. This gives flex
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the condensate rate, productivity f
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esult, rather than PCM media which
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Figure 7.18: Effect of PCM thermal
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8 Optimization of HDH plant In this
Page 184 and 185:
The MATLAB model describes how the
Page 186 and 187:
less steep than that of the distill
Page 188 and 189:
8.3.4 Effect of hot water flow rate
Page 190 and 191:
storage materials and thus it can h
Page 192 and 193:
for latent heat storage would be ob
Page 194 and 195:
When T m becomes sufficiently highe
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9 Summary and conclusions 9.1 Summa
Page 198 and 199:
productivities at any cooling water
Page 200 and 201:
[13] Vafai K., Sozen M. An investig
Page 202 and 203:
[48] Crone S., Bergins C., and Stra
Page 204 and 205:
[79] Tiwari G.N. and Yadav Y.P. (78
Page 206 and 207:
[109] Mehling H., Hiebler S. and Zi
Page 208 and 209:
[139] Belessiotis V, Delyannis E (2
Page 210 and 211:
Appendices Appendix A A1. PCM Therm
Page 212 and 213:
A3. Constants and Thermo-physical p
Page 214 and 215:
From the above correlation, the con
Page 216 and 217:
The Ergun analogy factor J h repres
Page 218 and 219:
Equation (C.7) represents an overal
Page 220 and 221:
Appendix D D1. Cooling tower theory
Page 222 and 223:
A m w = the plan or cross sectiona
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