Effects of Nonuniform Passages on Deepfold Heat Exchanger Performance

1977 ◽  
Vol 99 (4) ◽  
pp. 657-663 ◽  
Author(s):  
J. R. Mondt
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Experimental Measurements ◽  
Convective Transfer ◽  
Deviation Parameter ◽  
Manufacturing Tolerances ◽  
Flow Pressure ◽  
Fin Spacing ◽  
Fin Shape

To realize the maximum convective transfer of heat or mass, the fins in a plate-fin type heat exchanger must be exactly spaced for an unsupported length at least eight times the fin spacing. Manufacturing tolerances cause imperfect fin spacing and fin shape. These imperfections have been statistically modeled as either nonuniform fin spacing or “bulginess.” By statistically combining nonuniform fin spacing and bulginess into a unique “total channel deviation” parameter, convective transfer penalties and flow pressure drop gains can be predicted. Predictions are supported by experimental measurements.

Two-Phase Flow Pressure Drop Model for a Shell Side of a Shell of Heat Exchanger

2013 ◽  
Vol 465-466 ◽  
pp. 613-616 ◽  
Author(s):  
Azmahani Sadikin ◽  
Nor Zelawati Asmuin
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Momentum Flux ◽  
Liquid Fraction ◽  
Tube Bundle ◽  
Shell Side ◽  
Two Phase ◽  
Flow Pressure ◽  
Shell And Tube ◽  
Phase Pressure

This paper present a two-phase pressure drop model for a in-line tube bundle for airwater mixtures flowing through an idealised shell and tube, in-line heat exchanger. The model used momentum flux and entrained liquid fraction to predict the acceleration pressure drop. The model predicts the pressure drop well using both accelaration and gravitational pressure drop deduced from data available in open literature. The model is shown to be mass flux dependence.

CFD Study on Laminar Flow Pressure Drop and Heat Transfer Characteristics in Toroidal and Spiral Coil System

2004 ◽  
Author(s):  
Anthony J. Bowman ◽  
Hyunjae Park
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Heat Transfer Characteristics ◽  
Spiral Coil ◽  
Coil System ◽  
Transfer Characteristics ◽  
Flow Pressure ◽  
Toroidal Coil

Most pressure drop and heat transfer correlations obtained from the toroidal geometric system have been applied to the analysis of helical and spiral tube systems. While toroidal (and helical) coils have a constant radius of curvature about the coil center point (and center-line), spiral coils have a continuously varying radius of curvature, in which the varying centrifugal forces contribute to further enhance the heat transfer (at the cost of additional pressure drop) over toroidal and helical tube heat exchangers of the same length. Due to lack of published analytical, numerical and experimental data on spiral coil systems, in this paper, the laminar flow pressure drop and heat transfer characteristics of spiral coil systems are investigated with a commercially available CFD package (Fluent 6). First, an isothermal flow CFD analysis for a toroidal coil system is performed to optimally predict the local flow field and compared with the available experimental, numerical and analytical results, in which various model assumptions and operating conditions are involved. As a consequence, the heat transfer analysis with constant wall temperature boundary condition has been performed on a toroidal coil. With the verified CFD modeling schemes such as curved geometry creation, mesh/gird density control and solution model selection, the work is extended to the spiral coil system. The effects of Reynolds number and tube diameter to coil curvature ratio on the average friction factor and heat transfer characteristics are investigated for specified coil geometries utilizing water as the heat transfer medium. The general correlations for laminar flow pressure drop and heat transfer applied in a toroidal coil system are compared with the CFD results obtained from the spiral coil systems. It was found that up to 10% of the additional pressure drop and 40% of the enhanced heat transfer characteristics are obtained from the spiral coil system over the toroidal. The heat exchanger effectiveness ratio for spirals and toroids are compared for a range of Dean number. It was found that the spiral heat exchanger effectiveness ratio was between 20 to 30 percent greater than for general toroidal heat exchanger systems.

Single-Phase Flow Pressure Drop Analysis in a Plate Heat Exchanger

2016 ◽  
Vol 38 (2) ◽  
pp. 256-264 ◽  
Author(s):  
Tariq S. Khan ◽  
Mohammad S. Khan ◽  
Zahid H. Ayub
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Single Phase ◽  
Plate Heat Exchanger ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Plate Heat ◽  
Flow Pressure

Derivation of an Anisotropic Model for the Pressure Loss Through a Heat Exchanger for Aero Engine Applications

2009 ◽  
Author(s):  
Kyros Yakinthos ◽  
Stefan Donnerhack ◽  
Dimitrios Missirlis ◽  
Olivier Seite ◽  
Paul Storm
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Pressure Loss ◽  
Pollutant Emissions ◽  
Experimental Measurements ◽  
Loss Model ◽  
Aero Engine ◽  
Porosity Model

We present an effort to model the pressure loss together with the heat transfer mechanism, in a heat exchanger designed for an integrated recuperative aero engine. The operation of the heat exchanger is focusing on the exploitation of the thermal energy of the turbine exhaust gas to pre-heat the compressor outlet air before combustion and to decrease fuel consumption and pollutant emissions. Two basic parameters characterize the operation of the heat exchanger, the pressure loss and the heat transfer. The derivation of the pressure loss model is based on experimental measurements that have been carried-out on a heat exchanger model. The presence of the heat exchanger is modeled using the concept of a porous medium, in order to facilitate the computational modeling by means of CFD. As a result, inside the integrated aero engine, the operation of the heat exchanger can be sufficiently modeled as long as a generalized and accurate pressure drop and heat transfer model is developed. Hence, the porosity model formulation should be capable of properly describing the overall macroscopic hydraulic and thermal behavior of the heat exchanger. The effect of the presence of the heat exchanger on the flow field is estimated from experimental measurements. For the derivation of the porous medium pressure loss model, an anisotropic formulation of a modified Darcy-Forchheimer pressure drop law is proposed in order to take into account the effects of the three-dimensional flow development through the heat exchanger. The heat transfer effects are taken also into account with the use of a heat transfer coefficient correlation. The porosity model is adopted by the CFD solver as an additional source term. The validation of the proposed model is performed through CFD computations, by comparing the predicted pressure drop and heat transfer with available experimental measurements carried-out on the heat exchanger model.

scholarly journals Flow Rate Dependence of Ventilation

1987 ◽  
Vol 14 (1) ◽  
pp. 11-19
Author(s):  
DE Mathis
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Continuous Flow ◽  
Quantitative Model ◽  
Rate Dependence ◽  
Experimental Measurements ◽  
Flow Rates ◽  
Flow Dependence ◽  
Wide Range ◽  
Flow Pressure

AbstractA quantitative model describing the effects of puffing conditions on the level of filter ventilation was developed and evaluated. The development of the model was based on a quadratic flow-pressure drop relationship which was validated with experimental measurements for numerous plug wraps, tipping papers, and combinations of the two. This relationship was used to derive an equation describing the level of filter ventilation as a function of the flow rate of air exiting the filter. This equation was shown to accurately predict the measured ventilations of six brands of commercial cigarettes over a range of continuous flow rates. The instantaneous ventilation values predicted by the equation were utilized to model ventilation during a puff by integrating the equation with respect to flow rate over the duration of the puff. This method for predicting the effects of specific puffing conditions on ventilation was demonstrated for sinusoidally shaped puffs spanning a wide range of volume and duration. Finally, the effects on the flow dependence of ventilation of different combinations of plug wrap and tipping papers were described qualitatively based on experimental measurements of paper flow-pressure drop linearity.

scholarly journals Heat Transfer and Pressure Drop Characteristics of Angled Spiralling Tape Inserts in a Heat Exchanger Annulus

2001 ◽  
Author(s):  
H. Coetzee ◽  
L. Liebenberg ◽  
J. P. Meyer
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Single Phase ◽  
Experimental Measurements ◽  
Tube Heat Exchanger ◽  
Normal Tube

Abstract The purpose of this paper was to determine the single phase heat transfer and pressure drop characteristics of an angled spiralling tape inserted into the annulus of a tube-in-tube heat exchanger. Experimental measurements were taken on four setups: a normal tube-in-tube heat exchanger used as a reference and three heat exchangers with different angled spiralling tape inserts. From the results correlations were developed that can be used to predict the heat transfer and pressure drop characteristics. It was concluded that the angled spiralling tape inserts resulted in an increase in the heat transfer and pressure drop characteristics as can be expected.

Numerical Simulation of Frosting on Fin-and-Tube Heat Exchanger Surfaces

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Xiaomin Wu ◽  
Qiang Ma ◽  
Fuqiang Chu
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Air Flow ◽  
Layer Growth ◽  
Windward Side ◽  
Transfer Model ◽  
Pressure Drops ◽  
Tube Heat Exchanger ◽  
Flow Pressure ◽  
Good Agreement

Frost on heat exchanger fin surfaces increases the thermal resistance and blocks the air flow passages, which reduce the system energy efficiency. Therefore, investigations of frost formation especially simulations of frosting on the heat exchanger surfaces are essential for designing heat exchangers that operate with frosting. In this paper, the frost growth and densification processes on fin-and-tube heat exchanger surfaces are numerically investigated using a mass transfer model implemented as a user-defined function (UDF) in fluent. The model predicts the frost distributions on the heat exchanger surfaces, the temperature distributions, and the air flow pressure drop. The results show that the frost is thicker and the frost density is higher on the fin surfaces on the windward side near the tubes, while the frost is thinner and the density is lower near the inlet. Very little frost appears in the tube wake region. Frost on the fin-and-tube heat exchanger surfaces restricts the airflow and about doubles the pressure drop after frosting for 50 min. The simulated frost distributions and pressure drops are in good agreement with experimental data, which means that the frosting model can be used to predict frost layer growth on heat exchanger surfaces and the resulting airflow resistance.

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