An apparatus of flow calorimetry for liquids and the measurements of ethanol


T. Miyazawa1, S. Kondo2, T. Suzuki3 and H. Sato2

1Graduate School of Science and Technolagy, Keio University, Japan
2Department of System Design Engineering, Keio University, Japan
3JX Nippon Oil & Energy Corporation

Keywords: flow calorimetry
property: isobaric heat capacity
material: ethanol

Accurate measurements of isobaric heat capacities (cp) are the fundamental information for calculating heat transfer and thermodynamic performances of many industrial applications including air conditioning and refrigeration systems. Ethanol is expected to be used for various thermal energy systems as a heat-transportation medium or bio-fuel. Our group constructed a previous flow-calorimeter in 1996 for measuring specific heat-capacity at constant pressure of liquid HFC refrigerants with the highest accuracy at that time. Although we used this apparatus in many years, it is still keeping its important role in science and engineering in these fields. We developed a new mass-flow-measurement system and reconstructed the apparatus. We confirmed that the apparatus is able to measure isobaric heat capacities with the minimum heat loss, which is confirmed by the repeatability within the uncertainty. We measured isobaric heat capacities of two different sample liquid-ethanol provided from two different manufactures. The measured conditions are; a pressure of 500 kPa and temperatures between 280 K and 348 K. The purity of two different sample ethanol is 99.5 %. In addition, heat capacities of liquid ethanol at pressures, 500 kPa, 750 kPa, and 1 MPa were measured at the temperature of 320 K in order to confirm the pressure dependency of the heat capacity. Based on the measurements at the same condition, we confirmed the reproducibility. Furthermore, we measured two different sample ethanol to confirm the reliability of measurements. As a result, the expanded uncertainty was expected as being 0.57 to 0.91 % in specific heat value. Our measurements give the information that existing measurements and derived specific-heat-capacity values from existing equation of state developed by Dillon and Penoncello[1], and the measurements of other many researchers[2] ~ [5] have some systematic error beyond the respective uncertainties, we can provide smallest values of measurements and estimated uncertainty among existing information.

References
  1. H. E. Dillon, S. G. Penoncello, Int. J. Thermophys. 25(2), 321 (2004)

  2. G. S. Parks, Thermal Data On Organic Compounds. 47, 338 (1924)

  3. S. Mitsukuri, K. Har, Bulletin Chem. Soc. Jap. 4, 77 (1929)

  4. E. F. Fiock, D. C. Ginnings, W. B. Holton, Bur. Stand. J. Res. 6, 881 (1931)

  5. M. J. Pedersen, B. K. Webster, H. C. Hershey, J. Chem. Thermodyn. 7, 1107(1975)

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