Experimental Investigation of Isothermal VaporâLiquid Equilibrium

Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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Experimental Investigation of Isothermal Vapor−Liquid Equilibrium and Estimation of Excess Thermodynamic Properties (hE) of CHO2K− H2O from 278.15 to 423.15 K Gorakshnath D. Takalkar,*,†,‡ Rahul R. Bhosale,‡ Nilesh A. Mali,§ and Sunil S. Bhagwat*,† †

Department of Chemical Engineering, Institute of Chemical Technology, Matunga, Mumbai 400019, India Department of Chemical Engineering, College of Engineering, Qatar University, P.O. Box, 2713, Doha, Qatar § Chemical Engineering & Process Development Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune, 411008, India

J. Chem. Eng. Data Downloaded from pubs.acs.org by UNIV OF LOUISIANA AT LAFAYETTE on 03/18/19. For personal use only.

‡

S Supporting Information *

ABSTRACT: In this paper, vapor liquid equilibrium (VLE) of a binary mixture, potassium formate−water (CHO2K−H2O), was measured experimentally using a dynamic moving type VLE setup in the temperature range of 313.15 to 393.15 K. Overall, large vapor pressure data points generated for the mole fraction of CHO2K from 0.023 to 0.461 and the solution temperature up to 423.15 K were used to correlate the local composition-based activity coefficient model (NRTL model). The data obtained via the thermodynamic model fitting shows good agreement with the experimental VLE data with overall average relative deviation of 2.15% and root-mean-square deviation of 0.25%. The obtained results further indicate that the binary mixture exhibits a negative deviation from the Raoult’s law, which is an important characteristic of the working fluid used for a heat-activated vapor absorption system (VAS). Therefore, the CHO2K−H2O mixture can be considered as an alternative working pair that will overcome the limitations allied to the crystallization and corrosion of the commercial working fluids mainly lithium bromide− water (LiBr−H2O). The fitted nonrandom two-liquid model was further utilized to determine the excess thermodynamic properties, solution enthalpy, solution entropy, and equilibrium P−T−x (Duhring) plot.

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INTRODUCTION Heating, ventilation, air conditioning, refrigeration (HVAC&R) and related technologies are considerably expended to make our life comfortable. Moreover, these technologies have a very vital role in the food industries, cold storages, and air conditioning. Right now, the HVAC&R market is largely dominated by electricity driven vapor compression systems due to their inexpensive initial capital investment, requirement of smaller installation area, and the ease of operation, although vapor compression systems consume chemicals such as chlorofluorocarbon (CFC) and hydro-chloro-fluoro-carbon (HCFC) as refrigerants which results in hazardous environmental troubles such as global warming and reduction in the ozone layer. Even though the vapor compression cycle is well established in the HVAC&R field, the growing cost of electricity and requirement of diminishing the hazardous environmental © XXXX American Chemical Society

impacts and carbon footprint have motivated researchers to focus more toward the vapor absorption system (VAS).1 The VAS is one of the best alternatives to the vapor compression cycle, since it is operated with a supply of low grade thermal energy that can be obtained from various resources such as solar, biomass, geothermal, and industrial waste heat. Directly the VAS helps to overcome the issues associated with the shortage of high grade electricity, environmental pollution, electricity cost, and fossil fuels consumptions. Therefore, the VAS becomes a feasible and profitable option whenever low grade waste heat or renewable heat is abundantly available.2−4 Received: November 14, 2018 Accepted: March 6, 2019

A

DOI: 10.1021/acs.jced.8b01078 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

In addition, all the solutions were prepared using distilled water. Experimental Setup and Procedure. In this study, a moving type VLE setup (Figure 1) was exercised for the

Presently, the VASs are commercially operated in most of the industries by using lithium bromide-water (LiBr−H2O) and ammonia−water (NH3 − H2O) binary mixtures as working fluids. These binary mixtures possess characteristic drawbacks associated with the corrosion and crystallization of LiBr and high pressure operation, toxicity, and rectification of NH3.5,6 To overcome these issues associated with the LiBr−H2O mixture, researchers were led to investigate a state-of-the-art class of adsorbent-refrigerant combinations as potential alternative working fluids.6,7 The target is to utilize water as a green and natural refrigerant because it is nontoxic, environment friendly, economical, and has high latent vaporization energy. Due to the desirable properties such as less corrosion effect, good material compatibility, lower crystallization temperature, respectable thermal conductivity, suitable heat transfer rate, high solubility, and low viscosity,8 the aqueous solution of potassium formate (CHO2K) can be considered as an alternative for the LiBr−H2O mixture. The CHO2K−H2O mixtures have been extensively utilized as secondary fluids for indirect refrigeration,8−10 liquid desiccant for dehumidification of indoor air,11 in oil drilling industry, and as a deicer of road and runway, and as a liquid desiccant for solid oxide fuel cell in trigeneration12 and air craft.13,14 The complete list of thermo-physical properties of CHO2K−H2O such as density, heat capacity, thermal conductivity, and viscosity as desiccant for building applications was reported by Elmer.12 In addition thermo-physical properties such as viscosity, density, heat capacity, and vapor pressure of different ternary mixture of CHO2K was reported in the literature.15−18 However, based on the reported literature, the use of the CHO2K−H2O mixture toward VAS is rare. Furthermore, the published literature lacks a detailed thermodynamic study associated with the binary CHO2K−H2O solution.15,17,19,20 Reliable and accurate VLE data (for higher temperatures) are necessary for better understanding of the behavior of the CHO2K−H2O mixture toward VAS. Therefore, in this study, the thermodynamic properties of CHO2K−H2O solution were estimated by applying a vapor liquid equilibrium (VLE) state. The thermodynamic data obtained are valid for an extensive temperature range of 278.15 to 423.15 K and mole fraction of CHO2K in the range of 0.023 to 0.461. The data reported in this paper cover the operating region of the heat powered VAS for cooling purposes. This obtained equilibrium PTx VLE data were further correlated using an excess activity coefficient-based thermodynamic nonrandom two liquid (NRTL) model. Lastly, the thermodynamic properties such as enthalpy, entropy, equilibrium PTx plot were calculated by using NRTL and plotted for their utilization toward the VAS design.

Figure 1. Dynamic moving type VLE experimental setup with (1) sample vessel, (2) temperature sensor, (3) digital pressure gauge, (4) electric heating coil, (5) hot insulation, (6) external sampling vessel, (7) temperature indicator and controller, and (8) vacuum pump.

Table 2. Antoine Constants of Water for Temperature Range 278.15−342.15 K

EXPERIMENTAL SECTION Materials. Detail specifications of CHO2K used for the VLE experimentation are listed in Table 1. The CHO2K salt is Table 1. Component, Supplier, and Purity source

purity (mass%)

CAS no.

potassium formate (CHO2K) lithium bromide (LiBr)

590-29-4

SD Fine-Chem. Ltd.

99

7550-35-8

Thomas Baker (Chemicals) Pvt. Ltd.

99

values

A B C

16.26 3799.9 226.35

isothermal vapor pressure measurements at higher temperatures (in the range of 308.15−392.15 K). The VLE experimental setup comprises an equilibrium vessel (1) made up of SS 304a material with a total sample storage capacity of 350 mL. The equilibrium vessel was enclosed by an electrical heating coil and a 50 mm glass wool as a hot insulation material. The equilibrium sample volume was connected to a high capacity vacuum pump through isolation valves which are used to purge air from the sample space. The digital pressure gauge DVR 2 Vacuumbrand with a maximum operating pressure of 1080 mbar and measurement uncertainty of less than ±1 mbar was employed for the determination of the equilibrium isothermal vapor pressure. The rate of heating, utilized to maintain the sample set temperature, using a Pt 100 resistance type thermometer, was controlled by a PID temperature controller and indicator (accuracy ±0.1 K). First, the equilibrium vapor pressure measurement methodology was validated by determining the vapor pressure of the pure water and comparing the obtained data with the findings reported by “International Association for Properties of Water and Steam” called as IAPWS formulation 199721 (Table S1). The comparison yields an absolute relative deviation (in the case of water) equal to 1.06%, which confirmed that the methodology applied for the equilibrium vapor pressure measurement was appropriate. In addition, the vapor pressure of a binary mixture that is, LiBr−H2O for temperature of 313.15 to 373.15 K with molar fraction of LiBr of 0.0493 was measured and compared with the calculated vapor pressure by using the empirical formulations given by Patek and Klomfar.22 Comparison of equilibrium pressure shows a maximum ARD and RMSD of 0.88% and 0.92%, respectively, and likewise approves the reliability of the VLE experimental measurement for the binary mixture CHO2K−H2O. The experimental vapor pressure

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chemical name

Antoine constants

utilized for the VLE study without further purification. The digital weighing balance with 0.01 g resolution was employed. B



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Table 3. Physical Properties of CHO2K−H2O24 w2

crystallization temperature/K

viscosity/mPa

density/g/cm3

0.2 0.3 0.4 0.5 0.6 0.7

262.15 252.15 237.15 226.15 227.15 274.15

1.2 1.5 1.9 2.4 4.6 10

1.12 1.18 1.27 1.36 1.44 1.53

absorbent CHO2K in the liquid phase was utilized for the VLE study. Before each VLE measurement experiment, the VLE sample vessel was flushed by using distilled water and then dried twice by applying vacuum at room temperature for 30 min. In addition, before charging the specified CHO2K−H2O composition into the vessel, the VLE setup was evacuated with a minimum vacuum and then the equilibrium sample space was filled with the CHO2K−H2O mixture with the help of an external sampling vessel (80 mL). The isothermal VLE data was estimated by maintaining the temperature of the sample at the set point by using a thermostat. The temperature, pressure, and composition values were recorded once the thermal VLE was established. The isothermal experimental conditions employed in the case of the VLE measurements were decided based on the operating temperature range of the absorber and the generator in the VAS.

measurement is the mean of three independent equilibrium pressures for each temperature (Table S2). By using an electronic weighing scale (with an uncertainty of 0.01 g), the mass fraction of the CHO2K−H2O mixture was determined. The mass fraction of a known composition of the

Table 4. Experimentally Measured Equilibrium PTx Dataa for the CHO2K−H2O Binary Mixture from Solution Temperature (308.15 to 392.15 K) and Mole Fraction of Water (x1) from 0.539 to 0.824 x1

T/K

Pexpt/(kPa)

u(p)

0.824

308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 351.15 353.15 355.65 358.15 363.15 368.15 373.15 378.15 383.15 311.15 313.15 319.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 364.15 368.15 373.15 388.15 308.15 313.15 318.15 323.15 327.15 333.15 338.15 343.15 348.15 353.15 358.15

3.5 4.5 5.5 6.8 8.5 11 13.4 16.6 21.1 25.1 26.9 29.4 32.9 39.3 50 59.5 73 77.5 2.5 3.1 3.8 4.6 6.3 7.9 10 12.5 15.8 18.9 29 34 42 71 2 2.7 3.3 4.3 5 6.5 9 11.6 13.4 16.4 21

0.1 0.1 0.2 0.1 0.23 0.1 0.3 0.2 0.25 0.35 0.4 0.2 0.3 0.24 0.5 0.5 0.6 0.7 0.1 0.15 0.1 0.1 0.2 0.2 0.1 0.3 0.2 0.3 0.4 0.2 0.5 0.8 0.1 0.2 0.1 0.1 0.2 0.25 0.4 0.5 0.3 0.1 0.2

0.757

0.716

x1

0.667

0.609

0.539

T/K

Pexpt/(kPa)

u(p)

363.15 368.15 373.15 388.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15 392.15 323.15 333.15 338.15 343.15 348.15 350.15 353.15 358.15 363.15 369.15 373.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 373.15 380.65

26 31 36 60 1.6 2 2.8 3.6 4.4 5.5 6.8 8.4 10.8 13 17.4 21 24 30 54 3.1 4.5 5.5 6.8 9.8 11 11.8 15 16 20 22 1.1 1.3 2 2.7 3.5 4.8 6.5 7.65 10 12 21.3 28

0.3 0.3 0.3 0.6 0.1 0.1 0.2 0.1 0.2 0.1 0.1 0.2 0.1 0.3 0.3 0.2 0.2 0.3 0.4 0.1 0.1 0.2 0.2 0.2 0.2 0.2 0.3 0.4 0.2 0.1 0.1 0.1 0.1 0.1 0.2 0.15 0.2 0.2 0.1 0.2 0.3 0.2

a

Standard uncertainties are u(T) = 0.5K, u(x1) = 0.0023 and u(w) = 0.001. The standard uncertainties of pressure u(P) are given in the Table. C



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Table 5. Fitting Parameters of NRTL interaction parameter

α

a

b

c

d

% ARD

% RMSD

value

0.534

−2.7086

1816.259

−2.135

−144

2.15

0.25

Excess Thermodynamic Property. Margules and Van Laar, NRTL, universal quasichemical (UNIQUAC), and UNIQUAC functional-group activity coefficients (UNIFAC) are some of the several thermodynamic models used for the determination of the activity coefficients of the binary mixtures. The NRTL model is based on the local composition of the binary mixture, and it is applicable to partially miscible systems.23 In this investigation, the NRTL equations were considered to correlate the measured VLE data of CHO2K (2)−H2O (1) binary mixture (for x 2 of 0.023 to 0.461). The total and the partial pressure of water were equivalent and described as per following equation: p1 = P = P1satx1γ1

(1)

where γ1is the activity coefficient of water, x1is the mole fraction of water in the liquid phase, and P1sat is the saturation vapor pressure of pure water. Since the vapor pressure of CHO2K was negligible, the vapor pressure was equal to the vapor pressure H2O. By utilizing the NRTL model, the activity coefficient of water (γ1) has been correlated using eq 3 in terms of nonrandomness factor α, four temperature dependent (a, b, c, d) binary interaction parameters (τ12 and τ21) specific to the energy of the 1−2 interactions. ÑÉ ÅÄÅ G12τ12 ÑÑÑ Å G21τ21 ÑÑ GE = RTx1x 2ÅÅÅÅ + ÅÅÇ x1 + x 2G21 x 2 + x1G12 ÑÑÑÖ (2) ÄÅ É ÑÑ 2 ÅÅ i ÑÑ G21 G12τ12 jj zyz 2Å Å ÑÑ Å ln γ1 = x 2 ÅÅτ21jj + z 2Ñ ÑÑ ÅÅ jk x1 + x 2G21 zz{ ( + ) x x G ÑÑÖ 2 1 12 (3) ÅÇ ÄÅ ÉÑ 2 ÅÅ i ÑÑ y G G τ Å ÑÑ j z 12 21 21 zz + ÑÑ ln γ2 = x12ÅÅÅÅτ12jjj z 2 ÑÑ j z ÅÅ k x 2 + x1G12 { ( x + x G ) ÑÑÖ 1 2 21 ÅÇ

Figure 2. Vapor pressure parity plot of CHO2K−H2O mixture for x2 of 0.02 to 0.463 and the solution temperatures from 278.15 to 423.15 K.

RMSD =

The enthalpy (h) and the excess enthalpy (h ) of CHO2K− H2O solution was calculated by using eqs 11 and 12. Here, h1 and h2 were the enthalpies of water and CHO2K at the pure state. The enthalpy of pure CHO2K (h2) was calculated by using the specific heat capacity of pure solid CHO2K.9 h = x1h1 + x 2h2 + hE ÄÅ É Å d(GE /RT ) ÑÑÑ E 2Å Å ÑÑ h = −RT ÅÅÅ ÑÑ ÅÅÇ ÑÑÖ dT

G21 = exp( −ατ21)

(6)

τ12 = a +

b T

100 Np

(8)

ji |Pexpt − Pcal| zyz zz zz Pexpt k {

∑ jjjjj

(13)

Antoine constants required for computing the vapor pressure are listed in Table 2. The thermodynamic properties such as molar enthalpy and molar entropy of the refrigerant water were calculated by using the empirical equations reported in the IAPWS formulation 1997.21

The temperature independent model parameters a, b, c, d and nonrandomness factor α was obtained by fitting the NRTL equation to the measured experimental vapor pressure data14 for both lower and higher temperatures (from 278.15 to 423.15 K) and mole fraction of CHO2K from 0.023 to 0.461. The average deviation was predicted from the difference between the experimentally obtained vapor pressure and the vapor pressure calculated by using the thermodynamic NRTL model: %ARD =

(12)

i y B P sat /kPa = expjjjjA − ( )zzzz (T /°C) + C { k

(7)

τ21 = c + d /T

(11)

Thermodynamics Properties of Water. The vapor pressure of the water used in the VLE calculations was estimated by employing the Antoine equation:

in which G12 and G21 were (5)

(10) E

(4)

G12 = exp( −ατ12)

∑ [(Pcal − Pexpt)/Pexpt]2 /Np

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RESULTS AND DISCUSSION The precision of the activity coefficient model toward predicting the performance of the thermally activated VAS depends on the accuracy of predicting the thermodynamic properties (enthalpy, entropy) of the working fluid. The predicted thermodynamic properties are essential to determine the equilibrium steady state conditions in the absorber and generator of VAS. The physical properties, such as crystallization temperature, viscosity, and density of CHO2K−H2O mixture, as a function

(9) D



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Table 6. Comparison of Experimental and Predicted Equilibrium PTx VLE Data for Complete Solution Temperature (278.15 to 423.15 K) and Mole Fraction of Water x1 from 0.539 to 0.982 T/K 278.15

b

283.15b

288.15b

x1

Pexpt /kPa

0.982 0.968 0.954 0.943 0.924 0.920 0.910 0.891 0.879 0.870 0.861 0.845 0.825 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.982 0.968 0.954 0.943 0.924 0.920 0.910 0.891 0.879 0.870 0.861 0.845 0.825 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.982 0.968 0.954 0.943 0.924 0.920

0.843 0.817 0.789 0.766 0.719 0.709 0.984 0.635 0.606 0.583 0.563 0.525 0.48 0.44 0.418 0.386 0.35 0.344 0.311 0.293 0.268 0.259 0.24 0.222 0.217 0.212 0.193 1.187 1.15 1.111 1.077 1.011 1 0.963 0.896 0.855 0.824 0.796 0.741 0.679 0.623 0.592 0.547 0.497 0.487 0.443 0.416 0.381 0.369 0.343 0.317 0.311 0.303 0.277 1.648 1.596 1.543 1.495 1.404 1.389

Pcal /kPa 0.83 0.81 0.78 0.75 0.71 0.70 0.67 0.62 0.59 0.57 0.55 0.51 0.47 0.43 0.41 0.37 0.34 0.33 0.30 0.28 0.26 0.25 0.23 0.21 0.21 0.20 0.19 1.17 1.14 1.10 1.07 1.00 0.99 0.95 0.88 0.84 0.81 0.78 0.73 0.66 0.61 0.58 0.53 0.49 0.47 0.43 0.40 0.37 0.36 0.33 0.31 0.30 0.29 0.27 1.64 1.59 1.54 1.49 1.39 1.38 E

γexpt

γcal

Δ = |Pexpt − Pcal| /Pexpt

1.0 0.99 0.97 0.96 0.92 0.91 1.27 0.84 0.81 0.79 0.77 0.73 0.68 0.64 0.62 0.58 0.54 0.54 0.50 0.48 0.45 0.44 0.42 0.40 0.39 0.39 0.36 1.01 0.99 0.97 0.95 0.91 0.90 0.88 0.84 0.81 0.79 0.77 0.73 0.68 0.64 0.62 0.59 0.55 0.54 0.50 0.48 0.45 0.44 0.42 0.40 0.40 0.39 0.37 1.00 0.98 0.96 0.94 0.91 0.90

0.99 0.98 0.96 0.94 0.90 0.89 0.87 0.82 0.79 0.77 0.75 0.71 0.67 0.62 0.60 0.57 0.53 0.52 0.48 0.46 0.43 0.42 0.41 0.38 0.38 0.37 0.35 0.99 0.98 0.96 0.94 0.90 0.89 0.87 0.82 0.80 0.77 0.75 0.71 0.67 0.63 0.61 0.57 0.53 0.52 0.49 0.47 0.44 0.43 0.41 0.39 0.38 0.38 0.36 0.99 0.98 0.96 0.94 0.90 0.89

0.00 0.06 0.08 0.06 0.04 0.12 0.11 0.11 0.23 0.35 0.21 0.19 0.06 0.05 0.02 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.31 0.00 0.00 0.00 DOI: 10.1021/acs.jced.8b01078 J. Chem. Eng. Data XXXX, XXX, XXX−XXX


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Table 6. continued T/K

293.15b

298.15b

x1 0.910 0.891 0.879 0.870 0.861 0.845 0.825 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.982 0.968 0.954 0.943 0.924 0.920 0.910 0.891 0.879 0.870 0.861 0.845 0.825 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.982 0.968 0.954 0.943 0.924 0.920 0.910 0.891 0.879

Pexpt /kPa

Pcal /kPa

1.338 1.245 1.188 1.145 1.107 1.032 0.946 0.868 0.828 0.763 0.695 0.682 0.621 0.582 0.535 0.518 0.482 0.4454 0.437 0.426 0.391 0.381 0.381 2.259 2.188 2.115 2.05 1.926 1.905 1.835 1.709 1.632 1.573 1.521 1.419 1.302 1.196 1.14 1.051 0.959 0.941 0.857 0.805 0.74 0.718 0.668 0.617 0.606 0.59 0.542 0.528 0.53 3.06 2.964 2.865 2.777 2.609 2.582 2.487 2.318 2.213

1.33 1.23 1.17 1.13 1.09 1.02 0.93 0.85 0.81 0.75 0.68 0.67 0.61 0.57 0.52 0.51 0.47 0.43 0.43 0.42 0.38 0.37 0.37 2.25 2.19 2.11 2.05 1.92 1.90 1.82 1.70 1.62 1.56 1.50 1.40 1.29 1.18 1.12 1.04 0.95 0.93 0.84 0.79 0.73 0.70 0.66 0.60 0.59 0.58 0.53 0.52 0.52 3.06 2.97 2.87 2.78 2.61 2.57 2.48 2.30 2.20 F

γexpt

γcal


0.88 0.83 0.81 0.78 0.77 0.73 0.68 0.64 0.62 0.58 0.55 0.54 0.51 0.48 0.46 0.45 0.43 0.41 0.40 0.39 0.37 0.37 0.37 1.00 0.98 0.96 0.94 0.90 0.90 0.87 0.83 0.80 0.78 0.76 0.73 0.68 0.64 0.62 0.59 0.55 0.54 0.51 0.49 0.46 0.45 0.43 0.41 0.40 0.40 0.38 0.37 0.37 0.99 0.98 0.96 0.94 0.90 0.89 0.87 0.83 0.80

0.87 0.82 0.80 0.77 0.75 0.72 0.67 0.63 0.61 0.58 0.54 0.53 0.50 0.47 0.45 0.44 0.42 0.39 0.39 0.38 0.36 0.36 0.36 0.99 0.98 0.96 0.94 0.90 0.89 0.87 0.82 0.80 0.78 0.76 0.72 0.67 0.63 0.61 0.58 0.54 0.53 0.50 0.48 0.45 0.44 0.42 0.40 0.40 0.39 0.37 0.36 0.36 0.99 0.98 0.96 0.94 0.90 0.89 0.87 0.82 0.80

0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 DOI: 10.1021/acs.jced.8b01078 J. Chem. Eng. Data XXXX, XXX, XXX−XXX


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303.15b

308.15a,b

x1

Pexpt /kPa

0.870 0.861 0.845 0.825 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.982 0.968 0.954 0.943 0.924 0.920 0.910 0.891 0.879 0.870 0.861 0.845 0.825 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.589 0.982 0.968 0.954 0.943 0.924 0.920 0.910 0.891 0.879 0.870 0.861

2.135 2.065 1.927 1.769 1.627 1.552 1.431 1.307 1.283 1.169 1.099 1.01 0.98 0.913 0.844 0.829 0.808 0.743 0.724 0.726 4.099 3.97 3.839 3.72 3.495 3.459 3.333 3.108 2.969 2.865 2.77 2.587 2.377 2.187 2.088 1.926 1.761 1.728 1.577 1.482 1.365 1.323 1.233 1.141 1.121 1.092 1.005 0.98 0.983 0.878 5.43 5.26 5.086 4.929 4.634 4.585 4.418 4.122 3.94 3.802 3.676

Pcal /kPa 2.12 2.05 1.91 1.75 1.61 1.54 1.42 1.30 1.27 1.16 1.09 1.00 0.97 0.91 0.83 0.82 0.80 0.73 0.72 0.71 4.11 3.99 3.85 3.73 3.50 3.45 3.33 3.09 2.95 2.85 2.75 2.57 2.36 2.17 2.07 1.92 1.75 1.71 1.56 1.47 1.35 1.31 1.23 1.13 1.11 1.08 0.99 0.98 0.97 0.86 5.45 5.30 5.11 4.95 4.64 4.58 4.41 4.11 3.92 3.78 3.65 G

γexpt

γcal


0.78 0.76 0.73 0.68 0.64 0.62 0.59 0.55 0.54 0.51 0.49 0.46 0.45 0.43 0.41 0.41 0.40 0.38 0.37 0.37 0.99 0.97 0.95 0.94 0.90 0.89 0.87 0.83 0.80 0.78 0.76 0.73 0.68 0.64 0.62 0.59 0.55 0.55 0.51 0.49 0.46 0.45 0.43 0.41 0.41 0.40 0.38 0.37 0.38 0.35 0.99 0.97 0.95 0.93 0.90 0.89 0.87 0.83 0.80 0.78 0.76

0.78 0.76 0.72 0.68 0.64 0.61 0.58 0.55 0.54 0.50 0.48 0.46 0.45 0.43 0.40 0.40 0.39 0.37 0.37 0.37 0.99 0.98 0.96 0.94 0.90 0.89 0.87 0.82 0.80 0.78 0.76 0.72 0.68 0.64 0.62 0.58 0.55 0.54 0.51 0.49 0.46 0.45 0.43 0.41 0.40 0.40 0.38 0.37 0.37 0.34 0.99 0.98 0.96 0.94 0.90 0.89 0.87 0.82 0.80 0.78 0.76



Article


313.15a,b

318.15a,b

x1

Pexpt /kPa

0.845 0.825 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.589 0.824a 0.716a 0.667a 0.845 0.806 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.589 0.824a 0.757a 0.716a 0.667a 0.539a 0.795 0.777 0.757 0.752 0.731 0.716 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.589

3.435 3.161 2.91 2.779 2.564 2.347 2.305 2.102 1.978 1.821 1.766 1.648 1.527 1.5 1.461 1.345 1.311 1.315 1.172 3.5 2 1.6 4.507 3.825 3.652 3.374 3.089 3.034 2.769 2.608 2.402 2.33 2.175 2.016 1.98 1.929 1.777 1.732 1.736 1.551 4.5 3.1 2.7 2 1.1 4.755 4.395 4.027 3.957 3.612 3.403 3.136 3.043 2.842 2.635 2.59 2.522 2.325 2.267 2.272 2.03

Pcal /kPa 3.41 3.14 2.89 2.76 2.55 2.33 2.29 2.09 1.96 1.80 1.75 1.65 1.51 1.49 1.45 1.33 1.32 1.30 1.15 3.12 1.96 1.59 4.49 3.80 3.63 3.37 3.08 3.01 2.76 2.59 2.39 2.32 2.18 2.00 1.97 1.93 1.77 1.75 1.73 1.53 4.10 3.09 2.59 2.11 1.24 4.73 4.39 4.02 3.93 3.60 3.39 3.12 3.03 2.85 2.62 2.58 2.53 2.31 2.29 2.27 2.01 H

γexpt

γcal


0.73 0.68 0.64 0.62 0.59 0.55 0.55 0.51 0.49 0.47 0.46 0.44 0.42 0.41 0.40 0.38 0.38 0.38 0.36 0.76 0.50 0.43 0.72 0.65 0.62 0.59 0.56 0.55 0.52 0.49 0.47 0.46 0.44 0.42 0.41 0.41 0.39 0.38 0.38 0.36 0.74 0.56 0.51 0.41 0.28 0.63 0.59 0.56 0.55 0.52 0.50 0.47 0.46 0.44 0.42 0.42 0.41 0.39 0.38 0.38 0.36

0.72 0.68 0.64 0.62 0.59 0.55 0.54 0.51 0.49 0.46 0.45 0.44 0.41 0.41 0.40 0.38 0.38 0.38 0.35 0.68 0.49 0.43 0.72 0.64 0.62 0.59 0.55 0.55 0.51 0.49 0.47 0.46 0.44 0.42 0.41 0.41 0.38 0.38 0.38 0.35 0.68 0.55 0.49 0.43 0.31 0.62 0.59 0.56 0.55 0.52 0.49 0.47 0.46 0.44 0.42 0.41 0.41 0.39 0.39 0.38 0.36



Article


323.15a,b

328.15a

333.15a,c

338.15a

343.15a

348.15a

350.15a 351.15a 353.15a

355.65a

x1

Pexpt /kPa

Pcal /kPa

0.824a 0.716a 0.667a 0.539a 0.731 0.696 0.690 0.675 0.654 0.651 0.645 0.624 0.622 0.619 0.589 0.824a 0.757a 0.716a 0.667a 0.609a 0.539a 0.716 0.824 0.757 0.667 0.539 0.949c 0.875c 0.824 0.757 0.716 0.667 0.609 0.539 0.824 0.757 0.716 0.667 0.609 0.539 0.824 0.757 0.716 0.667 0.609 0.539 0.824 0.757 0.716 0.667 0.609 0.539 0.609 0.824 0.824 0.757 0.716 0.667 0.609 0.539 0.824

5.5 3.3 2.8 1.3 4.669 4.058 3.94 3.68 3.414 3.355 3.267 3.014 2.939 2.946 2.634 6.8 4.6 4.3 3.6 3.1 2 5 8.5 6.3 4.4 2.7 17.8 14.3 11 7.9 6.5 5.6 4.5 3.5 13.4 10 9 6.8 5.5 4.8 17.1 12.5 11.6 8.4 6.8 6.5 21.1 15.8 13.4 10.8 9.8 7.65 11 25.1 26.9 18.9 16.4 13 11.8 10 29.4

5.34 3.38 2.76 1.64 4.66 4.04 3.93 3.69 3.40 3.35 3.27 3.00 2.98 2.95 2.61 6.89 5.20 4.37 3.58 2.83 2.13 5.34 8.80 6.65 4.59 2.74 17.88 13.73 11.14 8.44 7.11 5.83 4.62 3.50 13.99 10.61 8.95 7.35 5.83 4.42 17.43 13.23 11.17 9.18 7.30 5.54 21.56 16.37 13.83 11.38 9.05 6.89 9.85 24.41 26.48 20.12 17.00 13.99 11.15 8.49 29.28 I

γexpt

γcal


0.70 0.48 0.44 0.25 0.52 0.47 0.46 0.44 0.42 0.42 0.41 0.39 0.38 0.39 0.36 0.67 0.49 0.49 0.44 0.41 0.30 0.47 0.66 0.53 0.42 0.32 0.94 0.82 0.67 0.52 0.46 0.42 0.37 0.33 0.65 0.53 0.50 0.41 0.36 0.36 0.67 0.53 0.52 0.40 0.36 0.39 0.66 0.54 0.49 0.42 0.42 0.37 0.43 0.70 0.69 0.53 0.48 0.41 0.41 0.39 0.68

0.68 0.49 0.43 0.32 0.52 0.47 0.46 0.44 0.42 0.42 0.41 0.39 0.39 0.39 0.36 0.68 0.56 0.50 0.44 0.38 0.32 0.50 0.68 0.56 0.44 0.32 0.95 0.79 0.68 0.56 0.50 0.44 0.38 0.33 0.68 0.56 0.50 0.44 0.38 0.33 0.68 0.56 0.50 0.44 0.38 0.33 0.68 0.56 0.50 0.44 0.39 0.33 0.39 0.68 0.68 0.56 0.50 0.44 0.39 0.33 0.68



Article

Table 6. continued T/K 358.15a

363.15a,c

364.15a 368.15a

373.15a

393.15a,c

423.15c

x1 0.824 0.716 0.667 0.609 0.539 0.949c 0.875c 0.757 0.824 0.716 0.667 0.609 0.757 0.824 0.757 0.716 0.667 0.609 0.824 0.757 0.716 0.667 0.609 0.539 0.667a 0.949 0.875 0.757 0.949 0.875 0.757

Pexpt /kPa

Pcal /kPa

32.9 21 17.4 15 12 66.7 54.5 36.2 39.3 26 21 16 29 50 34 31 24 20 59.5 42 36 30 22 21.3 54 192.7 151.5 78 450.2 363.3 186.2

32.31 20.75 17.09 13.62 10.39 62.90 48.24 29.77 39.18 25.17 20.74 16.54 30.92 47.22 35.88 30.34 25.00 20.69 56.58 42.99 36.34 29.95 23.91 18.27 56.63 178.10 136.50 83.98 427.44 327.66 200.51

γexpt

γcal


0.69 0.51 0.45 0.43 0.39 1.00 0.89 0.68 0.68 0.52 0.45 0.37 0.53 0.72 0.53 0.51 0.43 0.37 0.71 0.55 0.50 0.44 0.36 0.39 0.42 1.02 0.87 0.52 1.00 0.87 0.52

0.68 0.50 0.44 0.39 0.33 0.95 0.79 0.56 0.68 0.50 0.44 0.39 0.56 0.68 0.56 0.50 0.44 0.39 0.68 0.56 0.50 0.44 0.39 0.33 0.44 0.95 0.79 0.56 0.95 0.79 0.56

0.01 0.00 0.06 0.01 0.01 0.04 0.03 0.08 0.04 0.06 0.03 0.03 0.02 0.02 0.03 0.09 0.02 0.05 0.06 0.09 0.12 0.07 0.11 0.01 0.01 0.06 0.13 0.26 0.06 0.01 0.01

a

Present work. bLiterature data Beyer and Steiger.14 cLiterature data Atkinson.24

of CHO2K mass fraction (w2) are listed in Table 3.24 The data reported in Table 3 confirm that the crystallization temperature allied with the CHO2K−H2O binary mixture decreases from 262.12 to 227.15 K as the CHO2K mass fraction (w2) upsurges from 0.2 to 0.6. As the mass fraction of CHO2K further increases from 0.6 to 0.7, the crystallization temperature of the CHO2K−H2O binary mixture rises by 47 K. The presented data also indicates that the viscosity and density of the CHO2K−H2O binary mixture surges as a function of escalation in the mass fraction of CHO2K. For instance, as the mass fraction of CHO2K upswings from 0.2 to 0.7, the viscosity upturns by a factor of 8.34 and the density increases by 0.4 g/cm3. The information listed in Table 3 associated with the crystallization temperature of the CHO2K−H2O binary mixture shows that this mixture can overcome the crystallization limitations related to the LiBr−H2O.20 These remarkable properties of CHO2K−H2O binary mixture drive our interest toward predicting the performance of this mixture in the heat powered VAS for air-conditioning and refrigeration purposes. The suitability of the working pair, that is, the CHO2K− H2O binary mixture, can be determined by estimating the solubility of H2O in the CHO2K. The solubility of H2O in the CHO2K depends on the interaction between the H2O and CHO2K, and the reduction in the vapor pressure of H2O. In this investigation, the VLE associated with the CHO2K− H2O binary mixture was experimentally determined by

estimating the vapor pressure of the mixture in the high temperature range of 308.15 to 392.15 K (x1 from 0.539 to 0.824) as shown in Table 4. The combined vapor pressure data obtained after performing the experiments for a wide temperature range of 278.15 to 423.15 K are reported in the Supporting Information Table S3 and Table S4. This supporting document further enlists the vapor pressures of the CHO2K−H2O binary mixture for the temperature ranges of (a) 273.15 to 308.15 K (low temperature range) and (b) 393.15 to 423.15 K (high temperature range) experimentally determined by Beyer and Steiger14 and Atkinson.24 The high and low temperature VLE data (from 273.15 to 423.15 K) of the CHO2K−H2O binary mixture (reported in supporting document) was utilized to fit the NRTL model. By using open source software SCILAB 6,25 the computer program was developed for (a) the local composition NRTL model and (b) to estimate the thermodynamic properties of the CHO2K−H2O binary mixture and the pure water. The NRTL model constants (a, b, c, d and α) were obtained by fitting the experimental data to the local composition NRTL model by using the computer program developed via SCILAB 6. By utilizing the IAPWS formulation, the thermodynamic properties of the refrigerant water were estimated. Moreover, the activity coefficients of each component was evaluated by considering the local composition NRTL model. As the interaction parameters (τ12, τ21) of the NRTL model were considered J



Article

to be temperature dependent, the resulting parameters a, b, c, and d obtained in this work provide a better prediction of the vapor pressure and the activity coefficient over a wide range of temperatures and compositions. These fitting parameters validate the NRTL model for a wider range of the mole fraction of CHO2K (0.023 to 0.461) and mixture temperature ranging from 278.15 to 423.15 K. Table 5 lists the fitted NRTL model parameters a, b, c, d and nonrandomness factor α. The results reported in Figure 2 show that the vapor pressure of CHO2K−H2O binary mixture estimated with the help of the local composition NRTL model are in good agreement with the experimentally obtained data as presented in Table 6. Figure 3 depicts the % activity deviation [(ϒcal − ϒexpt)/ϒexpt]

Figure 4. Vapor pressure deviation at 303.15 K using NRTL model for CHO2K−H2O solution.

Figure 3. Percentage deviation of experimental data with the calculated activity coefficient using the NRTL model with mole fraction of water for a CHO2K−H2O mixture with solution temperatures from 278.15 to 423.15 K.

Figure 5. Vapor pressure validation using NRTL model at low temperatures from 278.15−323.15 K.

as a function of x1. Most of the data points reported in Figure 3 shows that the % deviation in case of the activity coefficient is in the range of ±5%. Figure 4 represents the deviation in the vapor pressure at 303.15 K for the real CHO2K−H2O binary mixture as compared to the ideal solution. It was observed that the binary mixture of CHO2K−H2O displays negative deviation from the ideal Raoult’s law. This leads to the enthalpy of solution being exothermic, which is the typical characteristic of the heat driven working fluids used in case of the VAS. The variations in the vapor pressure (both measured and correlated) as a function of the water mole fraction (x1) at different temperatures are shown in Figures 5 and 6. The plots reported in Figures 5 and 6 specify that the correlated vapor pressures obtained using a local composition NRTL model are in good agreement with the experimentally obtained vapor pressures for CHO2K−H2O binary mixtures. The average deviation was predicted based on the difference between the experimentally obtained and correlated (by using the NRTL model) vapor pressures. The percentage average relative deviation (ARD) and the root-mean-square deviation (RMSD) computed by comparing the predicted vapor pressures with the experimentally obtained vapor pressures are equal to 2.15 and 0.25, respectively as listed in Table 5.

The variation in the excess molar enthalpy (hE) as a function of composition was estimated by using eq 12 and trends are reported in Figure 7. Figure 8 represents the equilibrium relationship between P, T, and x (also called Duhring plot) which is mainly required to recognize the proximity of the crystallization possibility. By utilizing the Duhring plot the crystallization problem can be avoided by installing a control system for the operating cycle within the thermodynamic equilibrium limit. By using the excess properties, the enthalpy and the entropy of the CHO2K−H2O binary mixture were calculated and the variation in these properties is reported in Figures 9 and 10 (for temperature range of 273.15 to 373.15 K and mole fraction range of CHO2K from 0 to 0.55). The values reported in Figures 9 and 10 are useful for the prediction of performance and entropy generation in the VAS.

■

CONCLUSIONS The equilibrium vapor pressure measurement of the CHO2K− H2O binary mixture was carried out using a moving VLE setup in which the water mole fraction (x1) and the mixture temperature were varied from 0.53 to 0.824 and from 308.15−392.15 K, respectively. The theoretical vapor pressure was calculated K



Article

Figure 9. Enthalpy of CHO2K−H2O binary solution for 273.15 to 373.15 K with x2 from 0 to 0.55.

Figure 6. Vapor pressure validation using NRTL model at high temperatures from 328.15−373.15 K.

Figure 10. Entropy of CHO2K−H2O binary solution for 273.15 to 373.15 K with x2 from 0 to 0.55.

of experimental PTx data. Correlated activity coefficients were observed to be in good agreement with experimentally measured activity coefficients. Obtained results further show that the binary mixture exhibits a negative deviation from the Raoult’s law with an ARD of 2.15% and RMSD of .25% in between experimental and correlated VLE data. Finally the local composition NRTL model with the fitted five parameters was applied to evaluate the enthalpy and entropy of CHO2K−H2O binary mixture, and it can be useful toward the performance evaluation and design of VAS. Thus, the CHO2K−H2O binary mixture can meet the primary option as alternative working fluids in VAS and can found to be a more favorable alternative pair to LiBr−H2O. The application of the CHO2K−H2O binary mixture in VAS for cooling application needs to be further studied for different configurations using the reported enthalpy and entropy to evaluate the coefficient of performances.

Figure 7. Excess enthalpy of CHO2K−H2O binary mixtures with x1 for solution equilibrium temperature of T from 278.15−373.15 K.

■

ASSOCIATED CONTENT

S Supporting Information *

Figure 8. Equilibrium Duhring plot for CHO2K−H2O binary mixtures with weight fraction of CHO2K (w2) from 0 to 0.8.

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.8b01078. Experimentally measureda and calculated21 vapor pressure of H2O; experimentally measured and calculated equilibrium vapor pressure of LiBr−H2O solution for

using the NRTL model for which the four temperature dependency parameters were obtained by fitting a wide range L



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Article

Representation with an Ion Interaction (Pitzer) Model. J. Chem. Eng. Data 2010, 55, 830−838. (15) De Lucas, A.; Donate, M.; Rodríguez, J. F. Vapour Pressures, Densities, and Viscosities of the (Water + Lithium Bromide + Potassium Acetate) System and (Water + Lithium Bromide + Sodium Lactate) System. J. Chem. Eng. Data 2003, 48, 18−22. (16) Parab, P.; Bhagwat, S. Thermophysical Properties of Ternary Systems Potassium Formate + Propylene Glycol/Glycerol + Water. J. Chem. Eng. Data 2019, 64, 234−244. (17) Gao, N.; Chen, G.; Jiang, Y.; Fang, L.; He, Y. Heat Capacities of Four Promising Alternatives to Lithium Bromide Aqueous Solution in Absorption Refrigerators. J. Chem. Eng. Data 2013, 58, 3155−3159. (18) Dzuban, A. V.; Voskov, A. L.; Uspenskaya, I. A. Phase Diagram of HCOOK-(NH2)2CO-H2O System. J. Chem. Eng. Data 2013, 58, 2440−2448. (19) Riffat, S. B.; James, S. E.; Wong, C. W. Experimental Analysis of the Absorption and Desorption Rates of HCOOK/H2O and LiBr/ H2O. Int. J. Energy Res. 1998, 22, 1099−1103. (20) De Lucas, A.; Donate, M.; Molero, C.; Villaseñor, J.; Rodrıguez, J. F. Performance Evaluation and Simulation of a New Absorbent for an Absorption Refrigeration System. Int. J. Refrig. 2004, 27, 324−330. (21) Wagner, W.; Pruß, A. The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use. J. Phys. Chem. Ref. Data 2002, 31, 387−535. (22) Pátek, J.; Klomfar, J. A Computationally Effective Formulation of the Thermodynamic Properties of LiBr-H2O Solutions from 273 to 500 K over Full Composition Range. Int. J. Refrig. 2006, 29, 566−578. (23) Renon, H.; Prausnitz, J. M. Local Compositions in Thermodynamics Excess Functions for Liquids Mixtures. AIChE J. 1968, 14, 135−144. (24) Atkinson, S. Vapor Absorbent Compositions Comprising Potassium Formate. US Patent 5,846,450, 1998. (25) Scilab 6.0.1 Simulation & Modeling packaged open source Software, GNU General Public License (GPL) v2.0 https://www. scilab.org/about/scilab-open-source-software (accessed November, 15th 2018).

LiBr mass fraction of 0.2;22 literature equilibrium PTx data of CHO2K−H2O for the solution temperature (333.15 to 423.15 K) and mole fraction of water x1 from 0.757 to 0.949;24 literature equilibrium PTx data of CHO2K−H2O equilibrium PTx data for the solution temperature (278.15 to 423.15 K) and mole fraction of water x1 from 0.589 to 0.98214 (PDF)

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. Tel.: +91-2233612011. ORCID

Gorakshnath D. Takalkar: 0000-0002-0730-0845 Nilesh A. Mali: 0000-0001-6832-9230 Sunil S. Bhagwat: 0000-0002-1710-299X Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS G.D.T. gratefully acknowledge the British Petroleum (BP) International, UK, for providing fellowship during his Ph.D. research work.

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REFERENCES

(1) Dincer, I.; Mehmet, K. Refrigeration Systems and Applications, 2nd ed.; Wiley Publication: 2010. (2) Chen, H.; Goswami, D. Y.; Stefanakos, E. K. A Review of Thermodynamic Cycles and Working Fluids for the Conversion of Low-Grade Heat. Renewable Sustainable Energy Rev. 2010, 14, 3059− 3067. (3) Zeyghami, M.; Goswami, D. Y.; Stefanakos, E. A Review of Solar Thermo-Mechanical Refrigeration and Cooling Methods. Renewable Sustainable Energy Rev. 2015, 51, 1428−1445. (4) Siddiqui, M. U.; Said, S. A. M. A Review of Solar Powered Absorption Systems. Renewable Sustainable Energy Rev. 2015, 42, 93− 115. (5) Yokozeki, A.; Shiflett, M. B. Water Solubility in Ionic Liquids and Application to Absorption Cycles. Ind. Eng. Chem. Res. 2010, 49, 9496−9503. (6) Kalogirou, S. Recent Patents in Absoption Cooling Systems. Recent Patents on Mech. Eng. 2008, 1, 58−64. (7) Sun, J.; Fu, L.; Zhang, S. A Review of Working Fluids of Absorption Cycles. Renewable Sustainable Energy Rev. 2012, 16, 1899−1906. (8) Wang, K.; Eisele, M.; Hwang, Y.; Radermacher, R. Review of Secondary Loop Refrigeration Systems. Int. J. Refrig. 2010, 33, 212− 234. (9) Melinder, A. Thermophysical Properties of Aqueous Solutions Used as Secondary Working Fluids. Ph.D. Thesis, KTH Energy and Environmental Technology: 2007. (10) Aittomäki, A.; Lahti, A. Potassium Formate as a Secondary Refrigerant. Int. J. Refrig. 1997, 20, 276−282. (11) Sahlot, M.; Riffat, S. B. Desiccant Cooling Systems: A Review. Int. J. Low-Carbon Technol. 2016, 11, 489−505. (12) Elmer, T. A Novel SOFC Tri-Generation System for Building Applications. Ph.D. Thesis, University of Nottingham, 2017. (13) Hellstén, P. P.; Salminen, J. M.; Jørgensen, K. S.; Nystén, T. H. Use of Potassium Formate in Road Winter Deicing Can Reduce Groundwater Deterioration. Environ. Sci. Technol. 2005, 39, 5095− 5100. (14) Beyer, R.; Steiger, M. Vapor Pressure Measurements of NaHCOO + H2O and KHCOO + H2O from 278 to 308 K and M


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