Specific Heat Capacity at Constant Pressure of Ethanol by Flow

Article pubs.acs.org/jced

Specific Heat Capacity at Constant Pressure of Ethanol by Flow Calorimetry Taishi Miyazawa,*,† Satoshi Kondo,† Takuya Suzuki,‡ and Haruki Sato§ †

Graduate School of Science and Technology, ‡Former Graduate School of Science and Technology, and §Department of System Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan ABSTRACT: Specific heat capacities at a constant pressure of liquid ethanol in a temperature range from (265 to 348) K at a pressure of 500 kPa were measured by using flow calorimetry. The expanded uncertainty evaluated is from (0.55 to 0.89) % including the repeatability. Existing measurements by other researchers and derived specific heat capacity values from the existing equation of state provide greater values beyond the uncertainty. To confirm the reliability of our measurements, we measured the heat capacities under the same conditions for different liquid ethanol samples provided from different manufacturers. The measurements almost perfectly agree each other. The measurements obtained for two different samples of liquid ethanol are reported.

■

INTRODUCTION Accurate measurements of specific heat capacity at constant pressure (cp) are the important fundamental information for calculating heat transfer and thermodynamic performances of many industrial applications. Ethanol is an important fluid in chemical industries and increasingly promising to be used in energy industries such as biomass and low-temperature heattransportation media. Our group developed an apparatus of a flow calorimeter in 1985 for measuring cp of liquid hydrofluorocarbon (HFC) refrigerants.1−4 The improvement of the apparatus is continuously conducted. In 2008, we reconstructed the apparatus, having a new mass-flow-measurement system. The reliability of the massflow rate is improved, and simpler treatment of the apparatus was approved. The flow calorimetry apparatus can measure cp with negligible heat loss, which is confirmed by the repeatability among the measurements at different mass flow rates as discussed later. On the other hand, existing measurements by other researchers and derived specific heat capacity values from the equation of state developed by Dillon and Penoncello5 provide greater values of cp. To confirm the reliability very carefully, we measured cp for two different samples of liquid ethanol provided from two different manufacturers. The purities of the samples are reported as being better than (99.95 and 99.9) % in mass fraction by respective manufacturers. The measurement range is from (265 to 348) K at a pressure of 500 kPa. The expanded uncertainty is from (0.55 to 0.89) % in the cp value.

Table 1. List of Components in Ethanol from Wako Pure Chemical Industries, Ltd. component purity H2O nonvolatile component CH3COOH NH3 CH3COOH CH3OH (CH3)2CHOH CH3CH2CH2OH CH3(CH2)2CH2OH

better below below below below below below below below below

than 99.95 0.05 0.0005 0.002 0.0001 0.001 0.02 0.01 0.005 0.005

Table 2. List of Components in Ethanol from Ueno Chemical Industries, Ltd. component purity H2O nonvolatile component CH3COOH NH3 CH3COOH C6H6 CH3OH Cl Cu Fe Pb Ni

■

EXPERIMENTAL SECTION Sample Liquids. One of the sample liquids (sample A) was provided by Wako Pure Chemical Industries, Ltd. with a purity higher than 0.9995 in mass fraction. Another sample (sample B) © 2012 American Chemical Society

mass fraction in %

mass fraction in % better below below below below below below below below below below below below

than 99.90 0.3 0.0005 0.001 0.0001 0.0005 0.005 0.02 0.00004 0.000001 0.00001 0.000001 0.000001

Received: December 20, 2011 Accepted: April 23, 2012 Published: May 7, 2012 1700

dx.doi.org/10.1021/je2013473 | J. Chem. Eng. Data 2012, 57, 1700−1707

Journal of Chemical & Engineering Data

Article

was provided by Ueno Chemical Industries Ltd. with a purity higher than 0.999 in mass fraction. Tables 1 and 2 show the results of composition analysis of each ethanol. Experimental Procedure. Figure 1 shows a schematic of the most simple principle of flow calorimetry. A sample liquid of a constant temperature, pressure, and mass flow rate flows in the calorimeter. A sheathed thermometer and a microheater are installed in the calorimeter. A sample is given heat by the microheater. Temperatures before heating (T0) and after heating (Th) are measured by the thermometer. The temperature increment (ΔT) is determined from the difference between T0 and Th.

Figure 1. Principle of flow calorimetry.

Figure 2. Closed circuit of sample liquid flow. A = accumulator 1, B = accumulator 2, C = accumulator 3, D = pump, E = calorimeter, F = needle valve, G = three-way solenoid valve.

Figure 3. Circuit for measuring the mass flow rate. A = accumulator 1, B = accumulator 2, C = accumulator 3, D = pump, E = calorimeter, F = needle valve, G = three-way solenoid valve. 1701



Article

Figure 4. Overall view of the apparatus. A = pump, B = accumulator 1, C = constant temperature bath, D = calorimeter, E1 and E2 = crystal oscillation pressure gauges, F = constant temperature circulator, G = needle valve, H1 and H2 = digital pressure gauges, I = three-way solenoid valve, J = timer, K = electronic balance, L = accumulator 2, M = accumulator 3, N = differential pressure gauge, O = constant temperature bath, P = sample liquid bomb, Q1−Q3 = nitrogen gas buffers, R = nitrogen cylinder, S1 and S2 = Bourdon pressure gauges, T = mantle heater, U = temperature controller, V1−V34 = valves, W = digital multimeter, X = personal computer, Z = standard resistor, AA = DC power supply, AB = switch.

Figure 5. Constant temperature bath including a calorimeter. A = adiabatic material, B = calorimeter, C = standard platinum resistance thermometer, D1 and D2 = sheathed platinum resistance thermometers.

Figure 2 shows a sample liquid flow in the case of circulation. The sample liquid circulates in a closed loop including the calorimeter. Figure 3 shows a sample liquid flow while the mass flow rate is measured. When the mass flow rate is measured, flow channel is changed for two different lengths of time about (10 and 60) s by a three-way solenoid valve.

Figure 6. Calorimeter. a = radiation shield, b = microheater, D1 and D2 = sheathed platinum resistance thermometers.

The mass flow rate is determined from the difference between two different weights of sample liquid measurements 1702



Article

Table 3. Calibration among Three Thermometers

Table 6. Specific Heat Capacity of Ethanol Measured in 2009

average temperature

standard deviation

T

cp

U(cp)

T

cp

U(cp)

K

mK

K

kJ·kg−1·K−1

%

K

kJ·kg−1·K−1

%

318.428 318.425 318.426

1.6 1.4 3.2

300.011 305.021 310.000 315.008 320.003 325.003 330.004

2.376 2.417 2.443 2.480 2.542 2.602 2.638

61 69 67 75 75 74 58

333.008 335.003 338.013 339.990 342.997 345.001 348.003

2.668 2.692 2.746 2.767 2.823 2.841 2.867

0.89 0.66 0.68 0.68 0.61 0.63 0.67

entrance temperature exit temperature heating medium temperature

Table 7. Specific Heat Capacity of Ethanol Measured in 2010

Figure 7. Calibration of three thermometers: △, entrance temperature; ○, exit temperature; □, heating medium temperature.

T

cp

U(cp)

T

cp

U(cp)

K

kJ·kg−1·K−1

%

K

kJ·kg−1·K−1

%

265.005 270.007 273.004 275.013 280.000 285.007

2.215 2.234 2.247 2.265 2.287 2.312

0.59 0.55 0.56 0.57 0.60 0.58

290.009 294.986 300.028 305.003 310.006 320.006

2.337 2.356 2.381 2.417 2.451 2.545

0.65 0.63 0.66 0.61 0.64 0.58

Table 4. Measurements under Different Inverse of Mass Flow Rates at 345 K and 500 kPa ṁ −1

T

cp

s·g−1

K

kJ·kg−1·K−1

%

7.373 7.827 8.312 8.861 9.363 10.025

344.998 345.004 345.003 345.000 345.000 345.003

2.835 2.842 2.839 2.852 2.835 2.846

0.67 0.68 0.64 0.63 0.55 0.61

U(cp)

Figure 9. Comparison of data measured in 2008 to 2010: ×, this work (2008); ○, this work (2009); ●, this work (2010) with the uncertainty bars.

Table 8. cp of Liquid Ethanol at 320 K and (500, 1000, and 1500) kPa p

Figure 8. Measurements under different inverse of mass flow rates at 345 K and 500 kPa: ○, this work; ···, average of these six data.

K 300.004 310.022 315.006

cp −1

kJ·kg ·K 2.377 2.437 2.495

U(cp) −1

T

%

K

0.61 0.58 0.61

320.006 325.003 329.999

cp −1

kJ·kg ·K 2.533 2.606 2.656

U(cp) −1

kPa

K

500.3 997.9 1494.1

320.009 319.996 320.010

cp −1

kJ·kg ·K 2.549 2.553 2.538

U(cp) −1

% 0.61 0.58 0.62

in accumulator 3 which canceled the effect by changing the circuits. cp is obtained from the following equation. Q̇ cp = (1) ΔT ·ṁ −1 where Q̇ is the heat rate in J·s , ΔT is Th − T0 in K, and ṁ is the mass flow rate in g·s−1, respectively. Experimental Apparatus. Figure 4 shows an overall view of the apparatus, which consists of sample liquid circulatory and

Table 5. Specific Heat Capacity of Ethanol Measured in 2008 T

T

% 0.70 0.64 0.58 1703



Article

Table 9. Uncertainty of Sheathed Platinum Resistance Thermometer uncertainty factor of uncertainty

Figure 10. Pressure dependence in cp of liquid ethanol at 320 K: ○, this work; ···, average of these three data.

mK

note

standard platinum resistance

0.2

thermometer sheathed platinum resistance thermometer correlating equation of resistancetemperature temperature detector bridge

1.0 0.2

from proofreading result of NRLMa from experiment from specifications

3.0

from experimental data

0.27 1.0 3.3 6.6

from specifications from experiment

combined standard uncertainty expanded uncertainty (k = 2) a

Japanese National Research Laboratory of Metrology.

Table 10. Uncertainty of Temperature Measurements uncertainty factor of uncertainty

Figure 11. Comparison of the results with other measurements and an equation of state: , Dillon and Penoncello;5 □, Parks;6 ■, Mitsukuri and Har;7 ◊, Fiock et al.;8 ⧫, Pedersen et al.;9 △, Haida et al.;10 ▲, Al'per et al.;11 ×, this work (2008); ○, this work (2009); ●, this work (2010).

mK

combined standard uncertainty of sheathed platinum resistance thermometer temperature detector bridge standard deviation of measurement temperature

3.3

combined standard uncertainty expanded uncertainty (k = 2)

below 2.7 below 5.5

0.27 below 2

note

from experiment

Suppose Q̇ loss takes a constant value; the influence of heat loss is related to the flow rate. The measurements of heat capacities were performed by changing the flow rate at a temperature of 345 K and a pressure of 500 kPa. Table 4 and Figure 8 show the results. The measurements at different flow rates agree with each other within the uncertainty. So we could believe that our apparatus is able to measure isobaric heat capacities with negligibly small heat loss in this flow rate range. Furthermore, the repeatability could be confirmed by six times of measurement. Measurement of Heat Capacity for Liquid Ethanol. The cp of liquid ethanol at a temperature range from (265 to 348) K at a pressure of 500 kPa was obtained. Furthermore, to confirm the reliability, we measured isobaric heat capacities of two different liquid ethanol samples provided from two different manufacturers. So sample A ethanol was replaced by sample B ethanol in 2010. Tables 5, 6, and 7 show the results of cp of liquid ethanol measured from 2008 to 2010. Both samples A and B were commonly measured at temperatures between (300 and 320) K. Figure 9 shows the comparison of the measurements in this temperature range. The vertical uncertainty bars are attached to the measurements in 2010. As shown in Figure 9, all measurements are within the uncertainty. So, the repeatability is confirmed for two different samples. In addition, the cp of liquid ethanol at pressures of 500 kPa, 1 MPa, and 1.5 MPa were measured at a temperature of 320 K to confirm the pressure dependency of cp. Table 8 and Figure 10 show the result. As can be seen, based on the measurements at the same conditions, the reproducibility could be confirmed. Figure 11 shows comparison of the results with other existing measurements and the existing equation of state by Dillon

pressure-control systems with three accumulators, a calorimeter, and temperature-measurement systems. Figures 5 and 6 show the constant temperature bath including the calorimeter and the calorimeter itself, respectively. The sample liquid and heating medium come to a thermal equilibrium state in the constant temperature bath. After that, the sample liquid flows into a calorimeter, the temperature of the liquid at entrance is measured by a platinum resistance thermometer, D1, the liquid receives heat from a microheater, and then the temperature is measured by a thermometer D2. We could confirm that all temperatures of heating medium at the entrance and exit agree each other within an uncertainty. Table 3 and Figure 7 show the results. The uncertainty is discussed later. For calculating cp, temperatures measured before and after heating by the thermometer of D2 were used.

■

RESULTS AND DISCUSSION Reliability of Apparatus. To evaluate the reliability of the apparatus, heat loss from the calorimeter was examined. If measurements of heat capacities are affected by heat loss, these are expressed in the following equation. Q̇ + Q̇ loss Q̇ loss cp ,exp = = cp + (2) ΔT ·ṁ ΔT ·ṁ In this experiment, heat capacities are measured with the temperature increment (ΔT) as a constant value of 3 K. 1704



Article

Table 11. Details of Uncertainty in Table 4 T

P

cp

U(p)

U(T)

U(ΔT)

U(Q)

U(m)

U(cp)

K

kPa

kJ·kg−1·K−1

kPa

mK

%

%

%

%

344.998 345.004 345.003 345.000 345.000 345.003

499.4 499.7 501.4 502.0 501.2 500.9

2.835 2.842 2.839 2.852 2.835 2.846

6.6 6.6 6.6 6.6 6.6 6.6

4.9 4.9 4.9 4.9 4.9 4.8

0.33 0.33 0.33 0.33 0.33 0.32

0.21 0.01 0.03 0.01 0.01 0.01

0.54 0.59 0.55 0.54 0.44 0.52

0.67 0.68 0.64 0.63 0.55 0.61

U(p)

U(T)

U(ΔT)

U(Q)

U(m)

U(cp)

kPa

mK

%

%

%

%

6.6 6.6 6.6 6.6 6.6 6.6

5.0 5.1 5.1 5.1 4.9 5.0

0.32 0.33 0.33 0.34 0.32 0.34

0.01 0.16 0.01 0.04 0.01 0.01

0.39 0.45 0.51 0.61 0.40 0.46

0.61 0.58 0.61 0.70 0.64 0.58

U(p)

U(T)

U(ΔT)

U(Q)

U(m)

U(cp)

kPa

mK

%

%

%

%

6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6

4.9 4.8 4.8 5.1 5.0 4.9 4.9 5.1 5.1 5.0 5.0 5.0 4.9 5.0

0.32 0.31 0.32 0.33 0.33 0.33 0.33 0.34 0.34 0.33 0.34 0.34 0.33 0.33

0.18 0.04 0.01 0.03 0.01 0.01 0.01 0.05 0.04 0.04 0.13 0.01 0.05 0.02

0.56 0.62 0.59 0.68 0.67 0.66 0.48 0.82 0.57 0.59 0.57 0.51 0.53 0.59

0.67 0.69 0.67 0.75 0.75 0.74 0.58 0.89 0.66 0.68 0.68 0.61 0.63 0.67

U(cp)


P

K

kPa

300.004 310.022 315.017 320.006 325.003 329.999

505.7 503.1 505.7 501.2 503.6 501.7

cp −1

kJ·kg ·K

−1

2.377 2.437 2.495 2.533 2.606 2.656


P

K

kPa

300.011 305.021 310.000 315.008 320.003 325.003 330.004 333.008 335.003 338.013 339.990 342.997 345.001 348.003

505.1 498.7 498.6 498.3 498.9 503.4 506.9 504.1 505.7 502.2 501.8 501.6 500.8 502.2

cp −1

kJ·kg ·K

−1

2.376 2.417 2.443 2.480 2.542 2.602 2.638 2.668 2.692 2.746 2.767 2.823 2.841 2.867


P

cp

U(p)

U(T)

U(ΔT)

U(Q)

U(m)

K

kPa

kJ·kg−1·K−1

kPa

mK

%

%

%

%

265.005 270.007 273.004 275.013 280.000 285.007 290.009 294.986 300.028 305.003 310.006 320.006

500.7 500.2 499.9 499.8 499.6 501.4 502.6 503.7 502.5 500.7 500.1 502.1

2.215 2.234 2.247 2.265 2.287 2.312 2.337 2.356 2.381 2.417 2.451 2.545

6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6

5.2 4.9 5.0 5.0 4.8 4.8 5.1 4.8 4.9 4.8 4.9 4.8

0.35 0.33 0.33 0.34 0.32 0.31 0.33 0.32 0.31 0.32 0.32 0.32

0.02 0.04 0.04 0.07 0.02 0.09 0.02 0.04 0.05 0.02 0.03 0.02

0.47 0.44 0.44 0.44 0.51 0.48 0.56 0.54 0.58 0.52 0.56 0.48

0.59 0.55 0.56 0.57 0.60 0.58 0.65 0.63 0.66 0.61 0.64 0.58

1705



Article


P

cp

U(p)

U(T)

U(ΔT)

U(Q)

U(m)

U(cp)

K

kPa

kJ·kg−1·K−1

kPa

mK

%

%

%

%

320.009 319.996 320.010

500.3 997.9 1494.1

2.549 2.553 2.538

6.6 6.6 6.6

4.8 4.9 4.9

0.32 0.32 0.32

0.02 0.08 0.01

0.53 0.48 0.53

0.61 0.58 0.62

it could be concluded that our measurements are reliable enough, while those are the lowest values among available information.

and Penoncello. Currently the existing equation of state developed by Dillon and Penoncello is widely used to calculate thermodynamic properties of ethanol. The equation is stated as being valid in a single-phase region from (250 to 650) K and at pressures below 650 kPa. The dotted lines attached to the equation values are stated uncertainties of ± 3 %. The equation provides greater specific heat values about 10 % from our measurements at higher temperatures. Although a slope of our measurements and other existing measurements is getting smaller at lower temperatures, the equation shows a straight line from the lowest valid temperature of 260 K. The uncertainty of the specific heat vale calculated from existing equation of state by Dillon and Penoncello can be assessed about 10 %. Our measurements take the lowest values at higher temperatures. The developed apparatus can measure isobaric heat capacities with negligible small heat loss, and measurements of temperature and mass flow rate are almost completely stable within the sensitivities of measuring devices. We could confirm the repeatability of data measured by our group in 2008 to 2010. The purities of the samples used are better than 99.9 %. From the above facts, we believe that our measurements are reliable enough within the predicted uncertainty summarized below. On the other hand, our measurements are getting close to other measurements at lower temperatures. Uncertainty. All uncertainties of our measurements are examined based on the evaluation method of “Guide to the Expression of Uncertainty in Measurement” by ISO. Tables 9 and 10 show the details of uncertainty prediction for temperature measurements. Because heat capacity is determined from eq 1, the uncertainty of heat capacity is expressed by components of ΔT and Q̇ and ṁ . The uncertainty is principally calculated from the following equation under the coverage factor of k = 2. Uc(cp) =

⎛ U (Q̇ ) ⎞2 ⎛ U (ṁ ) ⎞2 ⎛ U (ΔT ) ⎞2 ⎟ +⎜ ⎟ ·c ⎜ ⎟ +⎜ ⎝ ṁ ⎠ ⎝ ΔT ⎠ p ⎝ Q̇ ⎠

■

APPENDIX All raw data which are included in pressure and inverse of mass flow rate discussions are listed (Table A1, A2, and A3). Table A1. Specific Heat Capacity of Ethanol Measured in 2008 p

T

ṁ −1

cp

kPa

K

s·g−1

kJ·kg−1·K−1

%

505.7 503.1 504.1 500.1 501.2 501.6

300.004 310.022 315.006 320.001 325.003 329.999

7.732 7.756 7.743 7.743 7.743 7.719

2.377 2.437 2.495 2.533 2.606 2.656

0.61 0.58 0.61 0.70 0.64 0.58

U(cp)

Table A2. Specific Heat Capacity of Ethanol Measured in 2009

(3)

Tables 11 to 15 show the predicted uncertainty for each measurement given in Tables 4 to 8, respectively. All experimental data with uncertainty are listed in the Appendix, Tables A1 to A3, for measurements in 2008 to 2010, respectively.

■

CONCLUSION Isobaric heat capacity of liquid ethanol at a temperature range from (265 to 348) K at a pressure of 500 kPa was obtained. The expanded uncertainty was evaluated as being (0.55 to 0.89) %. Our measurements are the lowest values in comparison with other existing measurements or existing equation of state by Dillon and Penoncello. We confirmed that our apparatus can measure isobaric heat capacities with negligible small heat loss. It was confirmed that the same cp values can be obtained for two different samples provided from two different manufactures. The repeatability of data measured in 2008 to 2010 is completely confirmed within the uncertainty. From these facts, 1706

p

T

ṁ −1

cp

kPa

K

s·g−1

kJ·kg−1·K−1

%

505.1 498.7 493.0 500.0 501.2 500.1 498.3 494.4 500.3 500.4 500.4 503.4 506.9 504.1 505.7 502.2 501.8 503.6 499.7 500.9 501.2 502.0 501.4 499.7 499.4 501.4 503.0

300.011 305.021 310.016 309.999 309.993 309.992 315.008 320.006 320.003 319.997 320.005 325.003 330.004 333.008 335.003 338.013 339.990 343.000 342.995 345.003 345.000 345.000 345.003 345.004 344.998 348.003 348.003

7.805 7.817 7.805 7.756 7.805 7.817 7.780 7.767 7.841 7.829 7.816 7.804 7.767 7.803 7.803 7.865 7.827 7.839 7.802 10.025 9.363 8.861 8.312 7.827 7.373 7.790 7.814

2.376 2.417 2.457 2.426 2.440 2.448 2.480 2.541 2.531 2.548 2.548 2.602 2.638 2.668 2.692 2.746 2.767 2.831 2.815 2.846 2.835 2.852 2.839 2.842 2.835 2.853 2.882

0.67 0.69 0.64 0.80 0.60 0.64 0.75 0.69 0.69 0.83 0.80 0.74 0.58 0.89 0.66 0.68 0.68 0.62 0.60 0.61 0.55 0.63 0.64 0.68 0.67 0.70 0.65

U(cp)



Article

(8) Fiock, E. F.; Ginnings, D. C.; Holton, W. B. Calorimetric determinations of thermal properties of methanol, ethyl alcohol and benzene. Bur. Stand. J. Res. 1931, 6, 881−900. (9) Pedersen, M. J.; Webster, B. K.; Hershey, H. C. Excess enthalpies, heat capacities, and excess heat capacities as a function of temperature in liquid mixtures of ethanol + toluene, ethanol + hexamethyldisiloxane, and hexamethyldisiloxane + toluene. J. Chem. Thermodyn. 1975, 7, 1107−1118. (10) Haida, O.; Suga, H.; Seki, S. Calorimetric study of the glassy state. XII. Plural glass-transition phenomena of ethanol. J. Chem. Thermodyn. 1977, 9, 1133−1144. (11) Al'per, G. A.; Peshekhodov, P. B.; Nikiforov, M. Y.; Krestov, G. A. Relation of the structural characteristics and the character of the variation of the excess heat capacity in binary solutions based on chloroform. Zh. Fiz. Khim. 1990, 64, 652−655.

Table A3. Specific Heat Capacity of Ethanol Measured in 2010

■

p

T

ṁ −1

cp

kPa

K

s·g−1

kJ·kg−1·K−1

%

500.7 500.7 497.8 502.1 501.4 500.5 497.9 501.9 497.6 499.2 500.3 499.4 501.4 502.6 503.7 502.5 501.5 500.2 500.3 499.7 500.5 502.1 499.7 500.8 994.6 1001.2 1497.7 1490.5

265.005 270.009 270.005 270.012 273.001 272.997 273.013 275.022 275.004 279.994 280.001 280.006 285.007 290.009 294.986 300.028 305.007 305.003 304.999 310.005 310.007 320.006 320.017 320.001 319.998 319.993 320.008 320.012

7.843 7.807 7.844 7.819 7.819 7.856 7.881 7.869 7.894 7.852 7.790 7.815 7.816 7.831 7.806 7.805 7.805 7.793 7.817 7.780 7.842 7.792 7.903 7.816 7.858 7.820 7.774 7.812

2.215 2.229 2.239 2.233 2.242 2.247 2.251 2.270 2.260 2.300 2.279 2.283 2.312 2.337 2.356 2.381 2.414 2.414 2.422 2.447 2.454 2.545 2.546 2.551 2.558 2.549 2.534 2.542

0.59 0.53 0.56 0.57 0.59 0.52 0.56 0.56 0.57 0.72 0.52 0.57 0.58 0.65 0.63 0.66 0.57 0.58 0.68 0.56 0.72 0.58 0.66 0.57 0.57 0.60 0.61 0.63

U(cp)

AUTHOR INFORMATION

Corresponding Author

*Tel.: +81-45-566-1729. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

■

REFERENCES

(1) Saitoh, A.; Sato, H.; Watanabe, K. A new apparatus for the measurement of the isobaric heat capacity of liquid refrigerants. Int. J. Thermophys. 1989, 10, 649−659. (2) Saitoh, A.; Nakagawa, S.; Sato, H.; Watanabe, K. Isobaric heat capacity data for liquid HFC-134a. J. Chem. Eng. Data 1990, 35, 107− 110. (3) Nakagawa, S.; Sato, H.; Watanabe, K. Measurement of isobaric specific heat of dichlorotrifluoroethane (HCFC-123) in the liquid phase. Thermochim. Acta 1990, 163, 203−210. (4) Nakagawa, S.; Sato, H.; Watanabe, K. Isobaric heat capacity data for liquid HCFC-123 (CHCl2CF3, 2,2-dichloro-1,1,1-trifluoroethane). J. Chem. Eng. Data 1991, 36, 156−159. (5) Dillon, H. E.; Penoncello, S. G. A fundamental equation for calculation of the thermodynamic properties of ethanol. Int. J. Thermophys. 2004, 25, 321−335. (6) Parks, G. S. Thermal data on organic compounds I. The heat capacities and free energies of methyl, ethyl and normal-butyl alcohols. J. Am. Chem. Soc. 1924, 47, 338−345. (7) Mitsukuri, S.; Har, K. Specific heats of aceone, methyl-, ethyl-, and n-propyl-alcohols at low temperatures. Bull. Chem. Soc. Jpn. 1929, 4, 77−81. 1707


Specific Heat Capacity at Constant Pressure of Ethanol by Flow

Recommend Documents