Open AccessDesign and assessment of an experimental facility for the characterization of flow boiling of azeotropic refrigerants in horizontal tubes
Author(s) -
Luigi Pietro Maria Colombo,
Andrea Lucchini,
Thanh Nhat Khoa Phan,
Luca Molinaroli,
Alfonso Niro
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1224/1/012037
Subject(s) - refrigerant , pressure drop , heat transfer coefficient , thermodynamics , heat exchanger , nucleate boiling , mechanics , heat flux , materials science , heat transfer , boiling , chemistry , physics
An experimental facility was designed to measure pressure drop and heat transfer coefficient during flow boiling of azeotropic refrigerants in horizontal tubes. The apparatus is made of the refrigerant circuit, including the test section; the water circuit, to provide the power for evaporation; the glycol-water circuit, to fix the refrigerant pressure. The test section is a counterflow tube-in-tube heat exchanger (refrigerant inside, water outside). Plant assessment involved the measurement of pressure drop and heat transfer during R134a flow boiling in a smooth tube (outer diameter 9.56mm, inner diameter 8.92mm). Such a case study is a benchmark for the availability of a wide experimental database in the literature, which has been also summarized in many correlations. Then further tests involved a microfin tube. The experimental conditions were: evaporation temperature, 5°C; mass flux, 111÷333kg/m 2 s; average quality, 0.15÷0.93; heat flux, 8.8kW/m 2 and 17.6kW/m 2 . The uncertainty affecting the pressure drop and the heat transfer coefficient resulted lower than 1% and 5% respectively. The comparison with the literature shows satisfactory agreement with the major findings and enables using the data for the assessment of the existing models to predict both the pressure drop and the heat transfer coefficient.