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Abstract

This thesis presents the results of an experimental investigation into the forced convection evaporation behaviour of two organic fluids, monochlorobenzene and the eutectic of biphenyl-biphenyl oxide, which are suitable as working fluids for low output Rankine cycle systems. Details are given of a high pressure and temperature experimental loop which was constructed for the investigation, which incorporated an electrically heated tube, 12.65 mm i.d. with a heated length of 1.83 m in which the test fluid flowed vertically upwards. The range of experimental conditions investigated were as follows:

[Table in thesis.]

It was found that the heat transfer in both the single-phase and sub-cooled boiling regimes could be described by existing correlations. In the net boiling region, however, this was not the case, and none of five literature correlations considered for comparison purposes adequately represented the experimental data. A correlation of the net boiling data was derived using multiple linear regression analysis, which employed the heat flux and liquid-vapour density ratio as the correlating variables. Heat transfer in the post dry-out region could be represented by a standard single-phase correlation employing vapour phase thermophysical fluid properties. The heat flux at dry-out was correlated for a number of tests in terms of the mass velocity, latent heat and vapour quality at dry-out. The high wall temperatures caused by dry-out promoted thermal breakdown of the test fluids, which served to highlight the prime importance of thermal stability considerations in Rankine cycle working fluid selection.

Included as appendices are the data reduction computer program, a digest of the thermophysical properties of the test fluid, an error analysis and a listing of experimental and derived data for each test undertaken. Further appendices give details of exploratory investigations concerning the thermal stability of monochlorobenzene, employing a gas chromatographic method for the chemical analysis of fluid samples taken before and after heating, dissolved gas measurement, and test section exit void fraction determination.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QC Physics T Technology > TJ Mechanical engineering and machinery T Technology > TP Chemical technology
Departments:	School of Science & Technology > Department of Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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