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

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A3. Constants and Thermo-physical properties of air and water Table A.3: Constants and Thermo-physical properties of air and water Properties Water Air Units Thermal conductivity 0.62 0.0264 W/m.K Dynamic viscosity at 50 °C. 2.4 e-03 1.87 e-05 N.s/m 2 Density at 50 °C. 998 1.177 kg/m 3 Surface tension 6.6 e- 02 - N/m Molecular weight 18.015e- 28.97e-3 kg/mol 3 Specific heat 4180 1006 J/kg.K Specific heat of water vapour & Humid air 1872 1015.952 J/kg.K Kinematic viscosity - 1.53 E-05 m 2 /sec Coefficient of volumetric thermal expansion - 0.003193358 K -1 (average for 0-80 °C) Coefficient of concentration expansion - 0.0023 % -1 (average for 0-80 °C) Binary diffusion coefficient at 50 °C. 2.77e-5 2.77e-5 m 2 /s The universal gas constant - 8.31447 J/mol.K Reference temperature - 273 K Reference density of air at 273 °K - 1.29 kg/m 3 Reference humidity of air at 273 °K - 0.00376 kg /kg Reference water vapour pressure at 273 °K 618.9 - Pa Latent heat of evaporation 45050 J/mol 193
Appendix B B1. Pressure drop calculations (Stichlmair et al. [29]) Stichlmair et al. [29] shows the advantages of the particle model. In this model structure, the real packing is replaced by a system of spherical particles which have the same surface and void fraction as the original packing. With these equivalence conditions, the equivalent diameter of the particle d p is: d 6 1 p (B.1) a Thus, the originally random structure of the packing is made accessible to calculation. Stichlmair et al. [29] show that the correlations for fluidized beds can also be applied to a system of fixed particles. The analysis of the pressure drop on the air side in a packed column was based on the computation of the dry column pressure drop and a correction term to account for the effect of liquid flow rate. Equation (27) describes the basic equation of the particle model. The dry column pressure drop per unit height that utilizes the single particle friction factor as well as the bed porosity ε is given by the following correlation [29]: d 4.65 2 gVg d p P Z 3 4 f (B.2) 0 1 where V g is the air superficial velocity and f is the friction factor given by the following equation: f 0.5 0 C1 Re g C2 Re g C (B.3) 3 where the friction factor f 0 for a single particle is a function of gas Reynold’s number: Re V d (B.4) g g g p g The friction factor f 0 is derived from the dry pressure drop of the original packing. Therefore, it is one of the characteristic parameters of a random and structured packing, together with the geometric surface a and the void fraction ε. The constants C 1 , C 2 and C 3 in equation (B.3) are available in Stichlmair et al [29] for different packing elements other than spherical packing. As long as the friction factor can be expressed in the same form of equation (B.3), the model can be applied for spherical packing (or any other packing geometry). Bird et al. [19] provides a simple and useful empirical expression for the friction factor for creeping flow around a sphere that matches the form of equation (B.3): 24 Re 0. 2 f 0 g 5407 for Re < 6000 (B.5) 194
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Technische Universität München In
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It is my pleasure to thank Prof. Th
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Contents List of figures ..........
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5.3 Functional description ........
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List of Figures Figure 1.1: Cost br
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78cm; Top: Evaporator, Bottom: Cond
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xii
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m Mass flow rate; [kg.s -1 ] m eva
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ed c coll cond cw d d e or eff evap
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1 Introduction The first part of th
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summarized in figure (1.2). Thermal
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1.3.2 Selection criteria of desalin
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of energy storage or hybridization
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Desalination development focuses on
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Introduction of the indirect type s
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2 Literature Survey 2.1 Introductio
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There is actually a commercial prod
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Q m H c ( T T1) c ( T 2 T ) (2.2)
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(solid-liquid) have a storage densi
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(iii) a sharp melting temperature.
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melt and freeze without segregation
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However, the stored heat is less va
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parameters on the heat transfer and
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categories. The first category is b
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to 550 kWh/m 3 of distilled water a
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The enthalpy and humidity of the sa
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Air mass flow rate [kg/h] GOR [-] 1
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On the other hand, the efficiency o
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2.8.4.2 Effect of air to water mass
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distillate rate. The system was not
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were; EnviPac Gr.1, 32 mm, and VFF
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Figure 2.15: Height versus air temp
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The performance of the condenser is
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Klausner and Mei [136] described a
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The impact of the collector cost ca
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exchanger and energy storage in one
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3 Scope of the Study This chapter p
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packing where it gets in direct con
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In fact there is a tradeoff between
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The energy flow between all and eac
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4 Theoretical Analysis and Modeling
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The two-energy equation models whic
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solid-liquid phase change inside th
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assumed by conduction in both axial
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the air pressure drop ∆P per unit
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evaporation rate per unit volume of
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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
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4.2.3.3 Liquid and gas hold-ups Liq
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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
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1 exp NTU 1 C r, cond cond (4
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A HE QHE U T HE LM (4.81) Where Q
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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
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The product condensed water was mea
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operating limits. In light of the l
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In the last two cases, the inlet ho
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performance and its threshold value
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It could be interpreted that this p
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Evaporator Condenser Figure 5.8: Av
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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
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6 Model Implementation and Validati
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x t u x u 0 0 , (6.5) and for a s
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Next time step validation were the
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The evaporator and condenser both w
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Figure 6.2: Evolution of inlet and
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Figure 6.4: Evolution of inlet and
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temperature is at its maximum level
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Bottom Top Figure 6.7: Evolution of
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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
Page 166 and 167: 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
Page 176 and 177: the condensate rate, productivity f
Page 178 and 179: esult, rather than PCM media which
Page 180 and 181: Figure 7.18: Effect of PCM thermal
Page 182 and 183: 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
Page 196 and 197: 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 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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