Heat transfer and pressure drop of R-134a condensation in a coiled, double tube

Mosaad, M.; Al-Hajeri, M. H.; Alajmi, R.; Koliub, Abo. M.

doi:10.1007/s00231-009-0484-y

Cited by 55 publications

(2 citation statements)

References 20 publications

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“…There are a number of experimental works concerning the FPD in smooth coiled tubes 14 – 21 . Mosaad et al 22 studied the R134a pressure drop inside a coiled tube with vertical direction flows. They found that the refrigerant mass velocity has a significant influence on the two-phase pressure drop.…”

Section: Introductionmentioning

confidence: 99%

Robust and universal predictive models for frictional pressure drop during two-phase flow in smooth helically coiled tube heat exchangers

Moradkhani

Hosseini

Mansouri

et al. 2021

Sci Rep

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There is a lack of well-verified models in the literature for the prediction of the frictional pressure drop (FPD) in the helically coiled tubes at different conditions/orientations. In this study, the robust and universal models for estimating two-phase FPD in smooth coiled tubes with different orientations were developed using several intelligent approaches. For this reason, a databank comprising 1267 experimental data samples was collected from 12 independent studies, which covers a broad range of fluids, tube diameters, coil diameters, coil axis inclinations, mass fluxes, saturation temperatures, and vapor qualities. The earlier models for straight and coiled tubes were examined using the collected database, which showed absolute average relative error (AARE) higher than 21%. The most relevant dimensionless groups were used as models’ inputs, and the neural network approach of multilayer perceptron and radial basis functions (RBF) were developed based on the homogenous equilibrium method. Although both intelligent models exhibited excellent accuracy, the RBF model predicted the best results with AARE 4.73% for the testing process. In addition, an explicit FPD model was developed by the genetic programming (GP), which showed the AARE of 14.97% for all data points. Capabilities of the proposed models under different conditions were described and, the sensitivity analyses were performed.

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Section: Introductionmentioning

confidence: 99%

Robust and universal predictive models for frictional pressure drop during two-phase flow in smooth helically coiled tube heat exchangers

Moradkhani

Hosseini

Mansouri

et al. 2021

Sci Rep

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“…Alhajeri et al [35] compared the pressure drop in a helical tube using R-134a with the pressure drop in a micro-finned straight tube as reported by Eckels and Tesene [14]. It was concluded that the Massad et al [34] compared the helical tube with other tube geometries and found that the loss in pressure was greater than for straight tubes, due to the greater complexity of the flow patterns in the helical tube. For these different tube arrangements, the same mass flux in the helical tube will contain swirls and a higher turbulence intensity, which results in higher pressure loss.…”

Section: Resultsmentioning

confidence: 99%

Condensation Heat Transfer of R-407C in Helical Coiled Tube Heat Exchanger

et al. 2020

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The results of an experimental study to evaluate the characteristics of R-407C thermofluid during condensation in a helically coiled copper tube heat exchanger are presented. The effects of saturation temperature (Tsat), and mass and heat fluxes of refrigerant R-407C on thermal performance and pressure drop were determined. The relationship between the refrigerant wall subcooling and heat transfer coefficients was also investigated. This paper reports the effect of the temperature of the water used as cooling medium on the heat transfer rate of condensing R-407C. The study was conducted with mass flux of R-407C in the range of 100–450 kg/m2s, mass flux of the coolant water in the range of 500–5000 kg/m2s and Tsat of 31 °C, 35 °C, and 39 °C. Compared with a straight smooth tube, the use of the helical coiled (helicoidal) tube increased the condensation rate with a corresponding pressure drop that depended on the value of Tsat of the refrigerant and temperature of the coolant.

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