Performance investigation of plain circular and oval tube evaporatively cooled heat exchangers
نویسنده
چکیده
The performance of two evaporatively cooled heat exchangers is analysed, one has plain circular tubes while the other one has plain oval tubes. Both are investigated under similar operating conditions in relation to airflow rates and inlet hot water temperatures. The circular tube is 10 mm o.d., and the oval tube (axes ratio 3.085) is formed from an 18 mm o.d. circular tube whose perimeter is preserved after forming. It is concluded that the average mass transfer Colburn factor ðjmÞ for the oval tube is 89% of that for the circular tube, while the average friction factor ðf Þ for the oval tube is 46% of that for the circular tube. The ratio ðjm=f Þ for the oval tube is 1.93–1.96 times that for the circular tube. This means that the oval tube has a better combined thermal–hydraulic performance. The heat-mass transfer analogy showed lower values for the mass transfer coefficient estimated from dry heat transfer correlations when compared with wet measurements. 2003 Elsevier Ltd. All rights reserved.
منابع مشابه
Pii: S1359-4311(02)00194-1
The performance of two evaporatively cooled heat exchangers is investigated under similar operating conditions of air flow rates and inlet hot water temperatures. The heat exchangers are plain and plate-finned circular tube types which occupy the same volume. Spray water, which is circulated in a closed circuit, is injected onto the exposed surfaces of the tubes and fins. The contact between ai...
متن کاملFull Analysis of Low Finned Tube Heat Exchangers
In this paper, first the governing parameters characterizing low-finned tubes are reviewed. Second, the more important of the available performance correlations are compared with the available experimental data. The most reliable one can be employed to develop a pressure drop relationship, which has already been used in an algorithm for exchanger sizing. Also a means for the identification of a...
متن کاملExperimental investigation of thermal and electrical performances of a nanofluid-cooled photovoltaic/thermal system equipped with a sheet-and-grooved serpentine tube collector
Introduction: In the present experimental investigation, the thermal and electrical performances of a photovoltaic/thermal system equipped with a sheet-and-grooved serpentine tube collector are investigated. The water-magnetite nanofluid is used as the heat transfer fluid. The effect of nanoparticle volume concentration (0-1%), nanofluid mass flow rate (10-40 kg/h) and groove pitch (0, 0.54 an...
متن کاملA numerical investigation of γ-Al2O3-water nanofluids heat transfer and pressure drop in a shell and tube heat exchanger
The effect of γ-Al2O3 nanoparticles on heat transfer rate, baffle spacing and pressure drop in the shell side of small shell and tube heat exchangers was investigated numerically under turbulent regime. γ-Al2O3-water nanofluids and pure water were used in the shell side and the tube side of heat exchangers, respectively. Since the properties of γ-Al2O3-water nanofluids were variable, they were ...
متن کاملThermal Design Considerations and Performance Evaluation of Cryogenic Tube in Tube Heat Exchangers
Heat exchangers are the most important equipment in refrigeration processes. Design and modeling of heat exchangers operating at low temperatures are different from other regular heat exchangers. This study includes two sections. In the first section, design and modeling considerations needed for evaluating the real thermal behavior of heat exchangers at low temperatures were discussed. The...
متن کامل