Francisco J. Uhía

Laboratory practices with the wilson plot method

The Wilson plot method is a well-known tool used in practical applications and research activities that involve the analysis of different heat exchanger devices. Therefore, it is of interest to researchers and engineers working on heat transfer and related fields. Moreover, the application of this method is simple enough to be taught in laboratory practices with students. Taking into account the reasons cited above, a simple experimental apparatus has been designed and built at our laboratory. In this article, the calculation procedure to apply the Wilson plot method is explained and characteristic experimental results for a smooth tube and a spirally corrugated tube are reported. Moreover, the experimental results are compared with different correlations proposed in the literature.

Experimental apparatus for measuring heat transfer coefficients by the wilson plot method

The Wilson plot is a technique to estimate the film coefficients in several types of heat transfer processes and to obtain general heat transfer correlations. This method is an outstanding tool in practical applications and in laboratory research activities that involve analysis of heat exchangers. Moreover, the application of this method is simple enough to be taught in laboratory practices for students at university and doctoral level of physics and engineering. Therefore, an experimental apparatus has been designed and built in our laboratory that allows the students to carry out experiments based on the application of the Wilson plot method. In this note, the principles of the method are explained, the experimental apparatus is described and representative results of the experimental data taken from the apparatus and the application of the Wilson plot method are shown.

Condensation of R22 Retrofit Substitutes R417A, R422A, and R422D on Horizontal Smooth Tubes

This article reports on the experimental research conducted to study the condensation of R22 retrofit refrigerants R417A, R422A, and R422D on Cu smooth tubes of 18.85 mm outside diameter. These retrofit substitutes are three-component mixtures. Experiments were carried out at vapor saturation temperature of 40°C and wall subcooling from around 1.8 to 16.7°C. The results clearly show the difference in behavior of the mixtures during condensation from that of a pure substance. A rapid increase of the heat transfer coefficients for low wall subcoolings was found. Comparisons of the condensation performance among the different refrigerant mixtures are also shown in the article.