Coupled Heat and Mass Transfer Analysis of an Adiabatic Dehumidifier – Unique Approach 1876 6102 © 2016 The Authors Published by Elsevier Ltd This is an open access article under the CC BY NC ND licen[.]
Available online at www.sciencedirect.com ScienceDirect Energy Procedia 90 (2016) 305 – 315 5th International Conference on Advances in Energy Research, ICAER 2015, 15-17 December 2015, Mumbai, India Coupled Heat and Mass Transfer Analysis of an Adiabatic Dehumidifier – Unique Approach B Kiran Naika, Ankit Sonia, Amit kumara, P Muthukumara*, C Somayajia a Deparment of Mechanical Engineering, Indian Institue of technology Guwahati, Guwahati-781039, India Abstract Liquid desiccant dehumidifier is one of the most desirable systems for dehumidification of air when compared to conventional refrigeration system and solid desiccant based dehumidifier In the present study, a finite difference model is developed to simulate the coupled heat and mass transfer processes occur in a counter flow adiabatic dehumidifier employing lithium chloride (LiCl) as a desiccant solution Mat-lab R13 is used as a simulation package for solving the aforementioned model This model has taken into the consideration of thermal effectiveness, effective height and moisture effectiveness as variable parameters for obtaining the correlation of the desired operating parameters The predicted numerical parameters for absorption process have good agreement with the experimental data reported in the literature This model is unique and can be extended to any type of liquid desiccant solution by changing the solution properties The performance analysis of adiabatic counter flow dehumidifier is also carried out by varying the operating parameters and the detailed results are presented in the full manuscript © 2016 The Authors Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license © 2016 The Authors Published by Elsevier Ltd (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the organizing committee of ICAER 2015 Peer-review under responsibility of the organizing committee of ICAER 2015 Keywords: Desiccant; dehumidification; heat and mass transfer; moisture effectiveness; condensation rate; Introduction In the traditional vapour compression or vapour absorption refrigeration system, process air is dehumidified by cooling below its dew point temperature and then reheating to the desired comfort temperature (required indoor * Corresponding Author Tel.: (+91) 361-2582673; Fax: (+91) 361-2690762 E-mail address: pmkumar@iitg.ernet.in 1876-6102 © 2016 The Authors Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the organizing committee of ICAER 2015 doi:10.1016/j.egypro.2016.11.198 306 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 conditions) This method is more energy consuming and is limited to lower cooling load capacity The best and economical way of dehumidification is by means of liquid desiccant solution This method is very popular due to its capability of removing latent load thereby minimizing the energy demand Dehumidifier is one of the important component of a liquid desiccant air conditioning system in which the concentrated solution is diluted The schematic of heat and mass transfer process that occurs across the dehumidifier is shown in Fig Initially, the concentrated solution is sprayed from the top of the packed tower and air (high RH) is circulated from bottom of the tower (in a counter flow direction) When the process air comes in contact with concentrated solution, desorption of moisture present in the process air occurs During this process, latent heat is released due to condensation of water vapor to solution side and chemical heat is released due to exothermic reaction (water vapor absorption by desiccant solution) Therefore remarkable rise in temperature of both air and desiccant solution takes place Nomenclature at cp G h T z specific surface area per unit volume (m2/ m3) specific heat at constant pressure (kJ/kg-K) specific mass flow rate (kg/m2-s) specific enthalpy (kJ/kg) temperature (°C) height of the tower (m) Greek letters β γ ξ λ δ ω m h concentration of the desiccant by mass (%) solution to air flow rate ratio effectiveness condensation rate (kg/m2-s) latent heat of vaporization (kJ/kg) air specific humidity ratio (kgv /kgda) mass transfer coefficient (kg/m2-s) heat transfer coefficient (W/m2-K) Subscripts a e i m o s T v air equilibrium inlet moisture outlet liquid desiccant solution thermal water vapour During absorption (dehumidification) process, heat and mass interactions occur between the air and the liquid desiccant solution The driving force for heat transfer is due to temperature difference whereas for mass transfer is their vapour pressure difference [1] The complicity of heat and mass transfer dealt way back from 1969 and Treybal [2] was the first person to describe the heat and mass transfer process occurred during dehumidification process by proposing a simple mathematical model From then, many researchers have developed various mathematical models for predicting the coupled heat and mass transfer characteristics occurred during dehumidification process using finite difference model [3-5], ɛ-NTU model [6-7] and simplified models [8-9] Fumo and Goswami [3], Babakhani et al [4] and Liu et al [5] compared their analytical solution with the experimental data and concluded that their B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 307 models were valid only with some reasonable assumptions Gandhidasan [8] introduced the dimensionless parameters such as moisture and thermal effectiveness and formulated the condensation rate in terms of heat exchanger effectiveness, mass flow rate of air and thermal effectiveness The proposed model has been compared with the experimental findings and found that the prediction matched within 10.5% with the experimental data Chung et al [10] developed a model for obtaining dimensionless heat and mass transfer correlations for both structured and random packing’s They found that the heat transfer coefficients were stronger function of the air flow rate than the solution flow rate Also, increasing the desiccant concentration reduces the heat transfer coefficients Fig Energy and mass balance across the dehumidifier Many researchers developed the finite difference model for predicting the coupled heat and mass transfer characteristics of an adiabatic dehumidifier [2-5] The uniqueness of the proposed model is the development of a correlation between the heat transfer coefficient and thermal effectiveness as well as for mass transfer coefficient and moisture removal effectiveness No one has correlated the moisture effectiveness and thermal effectiveness with the height of the dehumidifier which defines the performance as well as desired design conditions of a dehumidifier Also, using these correlations one can predict the exit parameters with known operating conditions very precisely Heat and mass transfer analysis of liquid desiccant dehumidifier A schematic of a counter flow heat and mass transfer processes occurred between air and desiccant solution is represented in Fig.1 To simplify the analysis, the following assumptions are made; • Dehumidification process is adiabatic • Change in mass flow rate of air is negligible • Properties of desiccant solution and ambient air is assumed to be constant with respect to the temperature • Heat and mass transfer interaction at the interface area are equal to the specific area of packing 308 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 2.1 Air side The enthalpy on air side is given by = C p ,aTa + ω (C p ,vTa + δ ) (1) On differentiation Eq dha = (C p ,a + ωC p ,v )dTa + d ω (C p ,vTa + δ ) (2) Energy balance across the air side flow is written as Ga (ha + dha ) − Ga = αh at (Ts − Ta )dZ + Ga dω (C p ,vTa + δ ) (3) Combining Eqs (2) & (3), the air temperature gradient is obtained as dTa α h at (Ts − Ta ) = dZ Ga (C pa + ωC pv ) (4) Eq can be integrated as Ta ,o ∫ Ta ,i z dTa −α h at =∫ dZ (Ta − Ts ) Ga (C pa + ωC pv ) (5) After integrating Eq 5, final equation can be obtained as (Ta ,i − Ta ,o ) ⎛ ⎞ −α h at z = − exp ⎜ ⎜ G (C + ωC ) ⎟⎟ (Ta ,i − Ts ,i ) pv ⎠ ⎝ a pa (6) The most common performance measures for evaluating the dehumidifier potential to dehumidify the ambient air are thermal and moisture effectiveness 2.1.1 Thermal effectiveness A dimensionless parameter given by Gandhidasan [8] in terms of outlet air temperature and inlet temperatures of ambient air and solution is ξT = (Ta ,i − Ta ,o ) (Ta ,i − Ts ,i ) (7) From Eqs.6 & 7, the thermal effectiveness (ξT) in terms of heat transfer coefficient (αh), height (h) and flow rate of air is formulated as ⎛ ⎞ −α h at z ⎜ G (C + ωC ) ⎟⎟ pv ⎠ ⎝ a pa ξT = − exp ⎜ (8) 309 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 2.1.2 Heat transfer coefficient From Eq.8, heat transfer coefficient in terms of thermal effectiveness and height is introduced as αh = Ga (c p ,a + ωC p ,v ) at z ⎛ ⎞ ln ⎜ ⎟ ⎝ − ξT ⎠ (9) 2.1.3 Mass balance for air side The mass transfer rate across the interface is equal to the change in humidity ratio and the equation is written as Ga dω = α m at (ωe − ω )dZ (10) Eq 10 is integrated as ωa ,o ∫ ω a ,i z α a dω = ∫ m t dZ (ωe − ω ) Ga (11) After integrating Eq.11, final equation can be obtained as ⎛ −α m at z ⎞ (ωi − ωo ) = − exp ⎜ ⎟ (ωi − ωe ) ⎝ Ga ⎠ (12) 2.1.4 Moisture effectiveness The moisture effectiveness based on specific humidity difference across the dehumidifier is given as follows [8] ξm = (ωi − ωo ) (ωi − ωe ) (13) From Eqs 12 & 13 the moisture effectiveness (ξm) in terms of mass transfer coefficient (αm), height (h), specific surface area of packing (at) and flow rate of air (Ga) is formulated as ⎛ −α m at z ⎞ ⎟ ⎝ Ga ⎠ ξm = − exp ⎜ (14) 2.1.5 Mass transfer coefficient From Eq.14, mass transfer coefficient in terms of moisture effectiveness and height is introduced as αm = ⎛ ⎞ Ga ln ⎜ ⎟ at z ⎝ − ξm ⎠ 2.2 Solution side Energy balance across the solution side flow is written as (15) 310 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 (Gs + dGs )( hs + dhs ) − Gs hs = α h at (Ta − Ts )dZ − Ga d ω (C p ,vTa + δ ) (16) The enthalpy on the solution side is given by dhs = C p , s dTs (17) 2.2.1 Condensation rate The rate of water vapour condensed (absorbed) from the ambient air to the solution side is referred as condensation rate (λ) and is given by d λ = −Ga dω (18) The change in the solution side flow rate is equal to the rate of water vapour condensed from the ambient air, it is written as (19) dGs = d λ By combining Eqs (16), (17) & (19) the solution side temperature gradient is obtained as dTs =− γ C p,s dZ dTa dω ⎛ − (C p,sTs − (C p,vTa + δ ) ) ⎞⎟ ⎜ (C p ,a + ωC p ,v ) dZ dz ⎝ ⎠ (20) where γ = Gs Ga 2.2.2 Mass balance for solution side Since the mass of the desiccant is constant during the desorption process, the mass balance across the solution side is written as Gs ,i β i = Gs ,o β o (21) The rate of water vapour condensed from the ambient air is transferred to the desiccant solution by a process known as absorption Simply, the condensation rate represents the amount by which the desiccant solution diluted So, Eq 21 can be formulated as Gs ,i βi = (Gs ,i + Ga (ωi − ωo )) β o (22) From Eq.22, the solution concentration at the outlet in terms of inlet flow rate, solution concentration and condensation rate is given by ⎛ ⎞ ⎜ ⎟ ⎟ βi βo = ⎜ ⎛ Ga (ωi − ωo ) ⎞⎟ ⎜ ⎟ ⎜ 1+ ⎜ ⎟ Gs ,i ⎠ ⎠ ⎝ ⎝ (23) Validation of model In order to use the developed mathematical model, with confidence, a proper validation is essential A comparison is made between the predicted values calculated from the developed mathematical model and experimental values 311 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 presented by the Chung and Gosh [10] During the experimental studies, a packed column of height 0.41m with the specific area of 223 m2/m3 was considered Table lists the inlet parameters considered for validating the developed model [10] and a comparison of typical experimental data for 16 cases [10] with the results obtained from the present study is presented in Table With reference to the results presented in Table 2, it is found that the predicted results obtained from the present model match well with the experimental data reported by Chung and Gosh [10] for the desiccant solution outlet temperature, the ambient air outlet temperature and humidity ratio and the water condensation rate In all the cases, the present mathematical model yields the air outlet temperature and specific humidity ratio and the desiccant solution outlet temperature slightly less than the experimental values The maximum and mean difference for air outlet temperature are -0.92 °C and -0.4 °C The specific humidity of air at the outlet and the solution outlet temperature differ as much as -4.35 % and -0.78 °C, whereas the average difference is about -1.84 % and -0.41 °C Developed model can’t be applied for predicting the desired outlet parameters when the inlet temperature of the solution and the process air are equal Table Inlet parameters that are used for validating the developed mathematical model [10] ṁa,i (kg/s) 0.0231 0.0260 0.0289 0.0318 0.0318 0.0318 0.0318 0.0318 0.0231 0.0260 0.0289 0.0318 0.0318 0.0318 0.0318 0.0318 Ta,i (°C) 21.8 21.6 20.4 21 24.1 23.4 23.3 24.1 23.3 22.9 20.9 20.8 21.1 20.9 20.8 20.7 ωi (kgwv/kgda) 0.0112 0.0111 0.0115 0.0117 0.0149 0.0147 0.0147 0.0147 0.0127 0.0126 0.0101 0.0105 0.0103 0.0103 0.0103 0.0103 ṁs,i (kg/s) 0.3071 0.3071 0.3071 0.3071 0.1919 0.2303 0.2687 0.3071 0.3071 0.3071 0.3071 0.3071 0.1919 0.2303 0.2687 0.3071 Ts,i (°C) 16.8 16.6 16.4 17.0 16.9 17.5 17.7 17.1 19.5 18.9 19.4 19.1 17.6 17.5 17.5 17.7 βi (% by mass) 31 31 31 31 31 31 31 31 37 37 37 37 38 38 38 38 Table Comparison of present outlet parameters with the predicted outlet parameters of Chung and Gosh [10] Exp 17.8 17.6 17.3 17.8 19.1 19.1 19.1 18.9 20.6 19.9 19.8 19.5 18.9 18.6 18.5 18.4 Ta,o (°C) Present 18.130 18.170 17.430 18.072 19.533 19.426 19.320 19.128 21.199 20.075 20.126 19.829 19.521 19.091 19.418 19.017 diff -0.33 -0.57 -0.13 -0.27 -0.43 -0.33 -0.22 -0.23 -0.60 -0.18 -0.33 -0.33 -0.62 -0.49 -0.92 -0.62 Exp 16.9 16.6 16.6 17.2 18.3 18.6 18.5 18.0 19.8 19.0 19.4 19.2 18.4 18.2 18.1 18.0 Ts,o (°C) Present 16.982 17.172 16.715 17.429 18.604 18.748 18.675 18.578 20.168 19.218 20.126 19.616 19.133 18.981 18.623 18.699 diff -0.29 -0.57 -0.12 -0.23 -0.31 -0.15 -0.18 -0.58 -0.37 -0.22 -0.73 -0.42 -0.73 -0.78 -0.52 -0.70 Exp 0.0064 0.0063 0.0066 0.0067 0.0080 0.0077 0.0075 0.0073 0.0058 0.0058 0.0051 0.0052 0.0049 0.0047 0.0046 0.0045 ωo (kgwv/kgda) Present 0.0065 0.0064 0.0067 0.0068 0.0081 0.0078 0.0076 0.0074 0.0059 0.0059 0.0052 0.0053 0.0050 0.0048 0.0048 0.0046 % Error -1.56 -1.59 -1.52 -1.49 -1.25 -1.30 -1.34 -1.37 -1.72 -1.72 -1.96 -1.92 -2.04 -2.13 -4.35 -2.23 Exp 0.1109 0.1248 0.1495 0.1649 0.2210 0.2226 0.2290 0.2353 0.1551 0.1768 0.1445 0.1685 0.1697 0.1751 0.1813 0.1831 λ (g/s) Present 0.1086 0.1222 0.1387 0.1558 0.2162 0.2194 0.2258 0.2321 0.1571 0.1742 0.1416 0.1654 0.1685 0.1749 0.1749 0.1813 % Error 2.07 2.08 7.22 5.51 2.17 1.44 1.40 1.36 -1.29 1.47 2.01 1.84 0.71 0.11 3.53 0.98 Fumo & Goswami [3], Gandhidasan [8] and Babakhani & Soleymani [4] studied the effects of various design parameters such as the inlet air temperature and humidity ratio, the inlet desiccant temperature and concentration, the air and the desiccant flow rate on the condensation rate in detail Hence, in this paper, the influences of air flow rate and the inlet temperature on both thermal effectiveness and moisture effectiveness during the dehumidification 312 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 process is presented in Figs 2(a) & 2(b) and 3(a) & 3(b), respectively A comparison between the experimental results presented by Chung and Gosh [10] and the present model is shown in aforementioned Figs Further, the effects of moisture effectiveness and thermal effectiveness and relative humidity on the condensation rate as well as the influence of solution to air flow ratio on the desiccant solution concentration are investigated using the present model Slope of thermal effectiveness and moisture effectiveness curve provides an estimation of the influence of these variables on the thermal and moisture effectiveness The thermal effectiveness and moisture effectiveness increase with the decrease in air flow rate with a slope of -1.0 & -0.9 (Figs 2(a) & 2(b)) It may be noted that at high flow rate, the air will be in contact with the desiccant solution for a shorter period of time, giving a lower change in temperature and specific humidity difference ratio (Figs 2(a) & 2(b)) The thermal effectiveness and moisture effectiveness enhance with the decrease of air inlet temperature with a slope of -0.42 & -0.6 (Figs 3(a) & 3(b)) and there is a linear increment of air inlet temperature for lower temperature and specific humidity difference ratio Since the temperature of the air and solution are highly dependent on the vapour pressures, at lower air inlet temperatures, the difference in vapour pressure of ambient air and desiccant solution is high therefore higher tendency of heat transfer from the ambient air to the solution side Fig Comparison of present model with the experimental data of Chung and Gosh [10]: a) Influence of thermal effectiveness on air flow rate and b) Influence of moisture effectiveness on air flow rate Fig.3 Comparison of present model with the experimental data of Chung and Gosh [10]: a) Influence of thermal effectiveness on air inlet temperature and b) Influence of moisture effectiveness on air inlet temperature 313 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 Results and discussions The operating parameters that are kept constant during the analysis are listed in Table Fig illustrates the moisture effectiveness obtained for different mass transfer coefficients at different tower height from 0.1 to 0.6 m In Fig 4, the variation of moisture effectiveness is determined using a new correlation developed in terms of mass transfer coefficient, tower height, air mass flow rate and specific area (Eq 14) For the given operating conditions, as the mass transfer coefficient increases, the moisture effectiveness is also found to increase Low the mass transfer from the ambient air to the solution side yields the lower value of moisture effectiveness This is due to the fact that as the mass transfer coefficient decreases the change in the solution concentration is also decrease and hence there is a decrease in the moisture effectiveness From Fig 4, it is also observed that the moisture effectiveness increases exponentially as a function of mass transfer coefficient with the increase in tower height This may be explained, as the height increases, contact time between the ambient air and solution side increases Hence, increase in moisture effectiveness takes place For a given αm of 0.4 g/m2-s, increasing the tower height from 0.1 to 0.6 m, increases the moisture effectiveness by 69 % Table Dehumidifier parameters used in the analysis Operating parameters Unit Operating range Air inlet temperature Specific humidity Air flow rate °C kgv/kgda Kg/s 22 0.012 0.0296 °C kg/s 17.7 0.2783 % by mass g/m2s W/ m2K m2/m3 m - 34 0.444 0.4 223 0.1-0.6 0.70 0.70 Desiccant inlet temperature Desiccant flow rate at the inlet 100 100 90 90 80 80 Moisture effectiveness Thermal effectiveness Desiccant concentration Mass transfer coefficient Heat transfer coefficient Specific area Tower height Moisture effectiveness Thermal effectiveness 70 60 50 40 h - 0.6 (W/m2K) h - 0.5 (W/m2K) h - 0.4 (W/m2K) 30 20 0.14 0.24 0.34 0.44 Tower height (m) 60 50 40 m - 0.6 (g/m2s) m - 0.5 (g/m2s) m - 0.4 (g/m2s) 30 20 10 10 0.04 70 0.54 0.64 Fig Effect of heat transfer coefficient on thermal effectiveness 0.04 0.14 0.24 0.34 0.44 Tower height (m) 0.54 0.64 Fig Effect of mass transfer coefficient on moisture effectiveness The effect of heat transfer coefficient on the thermal effectiveness is illustrated in Fig 5, by varying the tower height (0.1 to 0.6 m) for different heat transfer rates (0.4 to 0.6 W/m2-K) A new correlation which has been developed for thermal effectiveness (Eq 8) in terms of heat transfer coefficient, air mass flow rate, specific area and tower height is used for determining the variation of temperature difference ratio across the height of the 314 B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 dehumidifier Two defined tendencies have been observed from Fig One tendency is the apparent exponential increment of the thermal effectiveness for an increase in the tower height This is due to the fact that, as the tower height increases, the ambient air temperature (function of vapour pressure) increases, giving a lower change in heat transfer rate For a given αh of 0.6 W/m2-K, increasing the tower height from 0.1 to 0.6 m, increases the thermal effectiveness by 61 % The second defined tendency is the apparent increase in thermal effectiveness with increase in heat transfer rate This can be explained from Fig that lower the thermal effectiveness, lower the change in ambient air temperature and hence there is an apparent decrease in heat transfer coefficient The influence of relative humidity (R.H.) on the condensation rate (λ) is shown in Fig To investigate this effect, the relative humidity is varied from 70 % to 90 % that can be obtained during the peak summer seasons in a humid climate As illustrated, when the relative humidity is increased, the condensation rate is increased It happens because higher the R.H implies a higher air vapour pressure and consequently higher potential mass transfer From Fig 6, it is also observed that for a length 0.5 m, the condensation rate is constant in case of a relative humidity 90 % or 80 % or 70 % This is due to the fact that as the height increases, the difference in humidity ratio approaches to zero, which results in apparent decrease of heat and mass interactions between the ambient air and the desiccant solution and hence there is a constant condensation rate beyond a particular tower height for different relative humidity’s Therefore, it is advisable to have an optimum tower height depending upon the operating conditions Figure shows the results obtained for the concentration at different solution to air flow rate (L/G ratio) ratios, by varying the tower height from 0.1 to 0.6 m For any given flow rate ratio, as the height increases the solution concentration decreases Since the concentration is highly dependent on vapour pressure, the higher the solution vapour pressure, the lower the condensation rate and consequently gives the lower potential for mass transfer interaction From Fig 7, it is also observed that as the flow rate ratio increases desiccant solution concentration decreases This happens because as the flow rate ratio increases, the solution to air contact will be for shorter period of time, giving a lower change in concentration For a given γ = 0.5, increasing the tower height from 0.1 to 0.6 m, decreases the solution concentration by 3.3 % 0.25 34.3 Concentration (kgLiCl/kgsolution) 0.2 Condensation rate (g/m2s) 34.5 R.H - 90 % R.H - 80 % R.H - 70 % 0.15 0.1 0.05 0.04 0.14 0.24 0.34 0.44 0.54 0.64 Tower height (m) Fig Influence of relative humidity on condensation rate γ - 1.5 γ-1 γ - 0.5 34.1 33.9 33.7 33.5 33.3 33.1 32.9 32.7 32.5 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Tower height (m) Fig.7, Effect of concentration on solution to air flow ratio Conclusions Ambient air dehumidification process using strong desiccant solution (LiCl- H2O) has been studied by proposing a unique mathematical model using dimensionless parameters such as thermal effectiveness and moisture effectiveness in terms of heat and mass transfer coefficient The developed mathematical model has been shown very good agreement with the available experimental data [10] It is observed that operating variables such as solution to air flow rate ratio, air inlet temperature, relative humidity and heat and mass transfer coefficients have greater impact on dehumidifier performance It is also found that for a constant area beyond a certain tower height, the condensation rate for any relative humidity is nearly the same For a detailed study of absorption process across B Kiran Naik et al / Energy Procedia 90 (2016) 305 – 315 an adiabatic dehumidifier, this model gives more accurate prediction reducing computational time with some reasonable assumptions References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Killion JD, Garimella S A critical review of models of coupled heat and mass transfer in falling-film absorption J Ref 2001; 24: p.755–97 Treybal RE Mass transfer operations 3rd ed New York: McGraw-Hill; 1969 p 186–211 Fumo N, Goswami DY Study of an aqueous lithium chloride desiccant system: Air dehumidification and desiccant regeneration Solar Energy 2002; 72: p.351–61 Babakhani D, Soleymani M An analytical solution for air dehumidification by liquid desiccant in a packed column Int Comm Heat and Mass Transfer 2009; 36: p 969–77 Liu X, Jiang Y, Xia J, Chang X Analytical solutions of coupled heat and mass transfer processes in liquid desiccant air dehumidifier/regenerator Energy Conversion and Management 2010; 48: p 2221–32 Stevens DI, Braun JE, Klein SA An effectiveness model of liquid-desiccant system heat/mass exchangers Sol Energy 1989; 42: p 449–455 Chengqin R, Yi J, Yianpin Z Simplified Analysis of Coupled Heat and Mass Transfer Processes in Packed Bed Liquid DesiccantAir Contact System Sol Energy 2006; 80: p 121-9 Gandhidasan P A simplified model for air dehumidification with liquid desiccant Solar Energy 2004; 76: p 409–416 Ren C, Jiang Y, Zhang Y Simplified analysis of coupled heat and mass transfer processes in packed bed liquid desiccant-air contact system Sol Energy 2006; 80: p 121–31 Chung TW, Ghosh TK Comparison between random and structured packings for dehumidification of air by lithium chloride solutions in a packed column and their heat and mass transfer correlations Inds & Eng Chem Research 1996; 35: p 192-198 315 ... desiccant in a packed column Int Comm Heat and Mass Transfer 2009; 36: p 96 9–7 7 Liu X, Jiang Y, Xia J, Chang X Analytical solutions of coupled heat and mass transfer processes in liquid desiccant... coupled heat and mass transfer characteristics of an adiabatic dehumidifier [2-5] The uniqueness of the proposed model is the development of a correlation between the heat transfer coefficient and. .. transfer analysis of liquid desiccant dehumidifier A schematic of a counter flow heat and mass transfer processes occurred between air and desiccant solution is represented in Fig.1 To simplify the analysis,