Critical Heat Balance Error for a General Imbalanced Heat Exchanger

2016 ◽  
Author(s):  
Zhifeng Zhang ◽  
Bofeng Bai
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Entropy Generation ◽  
Heat Balance ◽  
Thermal Capacity ◽  
Inlet Temperature ◽  
Positive Entropy ◽  
Temperature Ratio ◽  
Heat Exchanger Design ◽  
Balance Error

The reliability of experimental data are important for heat exchanger design and evaluation. In the present paper, we extended the concept of Critical Heat Balance Error (CHBE) to a general imbalanced heat exchanger with thermal capacity ratio great than 1. Based on the principle of positive entropy generation in experiment, were analytically expressed the CHBE under the influence of different thermal capacity ratios. Interestingly, we found the same analytical expression as previous research which is, CHBE = −(1 − τ)(1 − ε), where ε and τ are heat exchanger efficiency and inlet temperature ratio, respectively. Therefore, we claim this analytical filter can be used for a general heat exchanger with any thermal capacity configuration.

Critical heat balance error for heat exchanger experiment based on entropy generation method

2016 ◽  
Vol 94 ◽  
pp. 644-649 ◽  
Author(s):  
Zhifeng Zhang ◽  
Yanfeng Zhang ◽  
Wenxue Zhou ◽  
Bofeng Bai
Keyword(s):  
Heat Exchanger ◽  
Entropy Generation ◽  
Heat Balance ◽  
Balance Error

Correlation Investigation of Condensation Heat Exchanger Design for Secondary Passive Cooling System

2012 ◽  
Author(s):  
Hee Joon Lee ◽  
Han-Ok Kang ◽  
Tae-Ho Lee ◽  
Cheon-Tae Park
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Cooling System ◽  
Condensation Heat Transfer ◽  
Passive Cooling ◽  
Heat Transfer Correlation ◽  
Data Set ◽  
Heat Exchanger Design ◽  
Passive Cooling System

Recently vertical or horizontal type condensation heat exchangers are being studied for the application to secondary passive cooling system of nuclear plants. To design vertical condensation heat exchanger in water pool, a thermal sizing program of condensation heat exchanger, TSCON (Thermal Sizing of CONdenser) was developed in KAERI (Korea Atomic Energy Research Institute). In this study, condensation heat transfer correlation of TSCON is evaluated with the existing experimental data set to design condensation heat exchanger without non-condensable gas (pure steam condensation). From the investigation of the existing condensation heat transfer correlation to the existing experimental data, the improved Shah correlation showed most satisfactory results for the heat transfer coefficient and mass flow rate in a heat exchanger in both subcooled and saturated water pools without the presence of non-condensable gas.

Consideration of Uncertainties in Compact Cross-Flow Heat Exchanger Design for Gas Turbine Engine Application

2013 ◽  
Author(s):  
Randall D. Manteufel ◽  
Daniel G. Vecera
Keyword(s):  
Fluid Flow ◽  
Heat Exchanger ◽  
Gas Turbine ◽  
Flow Rate ◽  
Cross Flow ◽  
Inlet Temperature ◽  
Fluid Flow Rate ◽  
Heat Exchanger Design ◽  
Cold Fluid ◽  
Flow Heat

Recent experimental work characterized the performance of a unique cross-flow heat exchanger design for application of cooling compressor bleed air using liquid jet fuel before it is consumed in the gas turbine combustor. The proposed design has micro-channels for liquid fuel and cools air flowing in passages created using rows of intermittent fins. The design appears well suited for aircraft applications because it is compact and light-weight. A theoretical model is reported to be in good agreement with experimental measurements using air and water, thus providing a design tool to evaluate variations in the heat exchanger dimensions. This paper presents an evaluation of the heat exchanger performance with consideration of uncertainties in both model parameters and predicted results. The evaluation of the design is proposed to be reproduced by students in a thermal-fluids design class. The heat exchanger performance is reevaluated using the effectiveness–NTU approach and shown to be consistent with the method reported in the original papers. Results show that the effectiveness is low and in the range of 20 to 30% as well as the NTU which ranges from 0.25 to 0.50 when the heat capacity ratio is near unity. The thermal resistance is dominated by the hot gas convective resistance. The uncertainties attributed to fluid properties, physical dimensions, gas pressure, and cold fluid flow rate are less significant when compared to uncertainties associated with hot fluid flow rate, hot fluid inlet temperature, cold fluid inlet temperature, and convective correlation for gas over a finned surface. The model shows which heat transfer mechanisms are most important in the performance of the heat exchanger.

Heat Exchanger Design Methodology for Electronic Heat Sinks

2006 ◽  
Vol 129 (7) ◽  
pp. 899-901 ◽  
Author(s):  
Ralph L. Webb
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Transfer Rate ◽  
Design Methodology ◽  
Design Method ◽  
Heat Sinks ◽  
Inlet Temperature ◽  
Heat Exchanger Design ◽  
Electronic Heat

This paper discusses the “inlet temperature difference” (ITD) based heat-exchanger (and its variants) design methodology frequently used by designers of electronic heat sinks. This is at variance with the accepted methodology recommended in standard heat-exchanger textbooks—the “log-mean temperature difference,” or the equivalent ε-NTU design method. The purpose of this paper is to evaluate and discuss the ITD based design methodology. The paper shows that the ITD based method is an approximation at best. Variants of the method can lead to either under- or overprediction of the heat transfer rate. Its shortcomings are evaluated and designers are directed to the well established and accepted design methodology.

scholarly journals Heat exchanger design based on minimum entropy generation

2019 ◽  
Vol 595 ◽  
pp. 012020
Author(s):  
S Bucsa ◽  
D Dima ◽  
A Serban ◽  
M-F Stefanescu ◽  
V Popa ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Entropy Generation ◽  
Minimum Entropy ◽  
Heat Exchanger Design ◽  
Minimum Entropy Generation

The Second Law Quality of Energy Transformation in a Heat Exchanger

1990 ◽  
Vol 112 (2) ◽  
pp. 295-300 ◽  
Author(s):  
D. P. Sekulic
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Entropy Generation ◽  
Exchange Process ◽  
Quantitative Measure ◽  
Inlet Temperature ◽  
Energy Transformation ◽  
Two Fluids ◽  
Heat Exchange Process

This paper presents the entropy generation (irreversibility) concept as a convenient method for estimating the quality of the heat exchange process in heat exchanger analysis. The entropy generation caused by finite temperature differences, scaled by the maximum possible entropy generation that can exist in an open system with two fluids, is used as the quantitative measure of the quality of energy transformation (the heat exchange process). This measure is applied to a two-fluid heat exchanger of arbitrary flow arrangement. The influence of different parameters (inlet temperature ratio, fluid flow heat capacity rate ratio, flow arrangements) and the heat exchanger thermal size (number of heat transfer units) on the quality of energy transformation for different types of heat exchangers is discussed. In this analysis it is assumed that the contribution of fluid friction to entropy generation is negligible.

Second Law Analysis in a Partly Porous Double Pipe Heat Exchanger

2005 ◽  
Vol 73 (1) ◽  
pp. 60-65 ◽  
Author(s):  
Nadia Allouache ◽  
Salah Chikh
Keyword(s):  
Thermal Conductivity ◽  
Porous Medium ◽  
Heat Exchanger ◽  
Effective Thermal Conductivity ◽  
Entropy Generation ◽  
Inlet Temperature ◽  
Two Fluids ◽  
Annular Gap ◽  
Double Pipe ◽  
Pipe Heat

A combination of the first and second laws of thermodynamics has been utilized in analyzing the performance of a double pipe heat exchanger with a porous medium attached over the inner pipe. The goal of this work is to find the best conditions that allow the lowest rate of entropy generation due to fluid friction and heat transfer with respect to the considered parameters. Results show that the minimization of the rate of entropy generation depends on the porous layer thickness, its permeability, the inlet temperature difference between the two fluids, and the effective thermal conductivity of the porous substrate. An increase in the effective thermal conductivity of the porous medium seems to be thermodynamically advantageous. Unexpectedly, the fully porous annular gap yields the best results in terms of the rate of total entropy generation.

Optimization of the Thermodynamic Efficiency of a Recuperative Heat Exchanger

2000 ◽  
Author(s):  
George A. Adebiyi
Keyword(s):  
Heat Exchanger ◽  
Thermal Capacity ◽  
Thermodynamic Efficiency ◽  
Second Law ◽  
Inlet Temperature ◽  
Counter Flow ◽  
Cold Stream ◽  
Prandtl Numbers ◽  
Recuperative Heat Exchanger

Abstract A heat exchanger is strictly speaking a thermal exergy transfer device, and the proper measure of its efficiency is the second law efficiency. This article considers the efficiency of a single-pass, recuperative heat exchanger in which a given stream of hot fluid is available for heating a cold stream of fluid in a specified manner. The analysis takes cognizance of the required exergy input to overcome fluid friction in the flow passages, as well as the thermal exergy flow rates for the fluid streams, in the determination of the second-law efficiency. Maximization of the second-law efficiency is found to provide a basis for sizing the heat exchanger for optimum thermodynamic efficiency of operation. The key parameters that determine this optimum include the number of transfer units (NTU), the ratio of thermal capacity rates (Cr), a dissipation parameter which involves the Eckert and Prandtl numbers, and the flow configuration (whether parallel-flow, or counter-flow). Other parameters relevant to the performance of the heat exchanger are the tare capacity (εtare), and the ratio of the inlet temperature of the hot fluid to the ambient temperature.

scholarly journals Application of artificial neural network (ANN-MLP) for the prediction of fouling resistance in heat exchanger to MgO-water and CuO-water nanofluids

2021 ◽  
Author(s):  
Ahmed Benyekhlef ◽  
Brahim Mohammedi ◽  
Djamel Hassani ◽  
Salah Hanini
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Artificial Neural Network ◽  
Heat Exchanger ◽  
Coefficient Of Determination ◽  
Percentage Error ◽  
Inlet Temperature ◽  
Fouling Resistance ◽  
Data Points ◽  
Artificial Neural

Abstract In this work an artificial neural network model was developed with the aim of predicting fouling resistance for heat exchanger, the network was designed and trained by means of 375 experimental data points that were selected from the literature. This data points contains 6 inputs, including time, volumetric concentration, heat flux, mass flow rate, inlet temperature, thermal conductivity and fouling resistance as an output. The experimental data are used for training, testing and validation the ANN using multiple layer perceptron (MLP). The comparison of statistical criteria of different networks shows that the optimal structure for predicting the fouling resistance of the nanofluid is the MLP network with 20 hidden neurons, which has been trained with Levenberg–Marquardt (LM) algorithm. The accuracy of the model was assessed based on three known statistical metrics including mean square error (MSE), mean absolute percentage error (MAPE) and coefficient of determination (R2). The obtained model was found with the performance of {MSE = 6.5377 × 10−4, MAPE = 2.40% and R2 = 0.99756} for the training stage, {MSE = 3.9629 × 10−4, MAPE = 1.8922% and R2 = 0.99835} for the test stage and {MSE = 5.8303 × 10−4, MAPE = 2.57% and R2 = 0.99812} for the validation stage. In order to control the fouling procedure, and after conducting a sensitivity analysis, it found that all input variables have strong effect on the estimation of the fouling resistance.

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