International Research Journal of Engineering and Technology (IRJET) Volume: 04 Issue: 02 | Feb -2017
e-ISSN: 2395 -0056
www.irjet.net
p-ISSN: 2395-0072
Heat transfer enhancement in fire tube boiler using hellically ribbed tubes Miss Simantini Balasaheb Kute
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Keywords- Heat transfer enhancement, Fire tube boiler, Plain tube, Helically ribbed tube.
the near critical pressure region. In this experiment, smooth tube and rifled tube were tested to study their heat transfer characteristic. The experiment result shows that when pressure exceeds 20.6MPa, the swirl effect will diminishes and CHF condition appears even in the sub cooled region. However, the wall temperature rise is suppressed to a comparatively lower lever. Dirar, S. et al [5] studied the CFD analysis of normal and rifled tube with a convergence check. As a result of CFD analysis, the maximum outlet temperature in rifled tube is higher than the normal tube.
1. Introduction
2. Theoretical analysis
Recently the energy drives the economy which leads to enhancement of energy efficiency. The researchers are interested in power generation field to control the use of energy and the economy as well. This study is about improving the heat transfer coefficient in tubes of fire tube boiler. The increase of heat transfer coefficient is occurred by change the internal geometry of the tube by helically ribbed shape. This helically ribbed shape generates a centrifugal force on the fluid and forces the flow to be turbulence. A plain tube has a problem which is the excessive time to heat the tube and this problem needs to be tackled. The objective of this study is to determine the heat transfer rate for both helically ribbed tube and plain tube. Smith, J. W. et al. [1] studied the turbulent heat transfer and temperature profiles in a rifled pipe. The rifled pipe was made by fitting snugly the continuous spiral rib inside a smooth brass tube which had the inner diameter of 2.058 inch. The continuous spiral rib was created from 0.25 inch x 0.25 inch copper bar with pitch to diameter ratio of 2.58. Zarnett, G. D. & Charles, M. E. et al. [2] studied the flow patterns of two phase flow in horizontal tubes fitted with internal spiral tubes (rifled tube) which their pitch to diameter ratios is 1.57 and 2.79 respectively. Webb, R. L. et al. [3] studied the heat transfer and friction correlations for turbulent flow in repeated-rib roughness tube. The correlation which was proposed by the authors specifically apply to ribs of rectangular cross-section, whose thickness is small relative to the rib spacing. Iwabuchi, M. et al. [4] studied the heat transfer characteristics of rifled tube in
In the nucleate boiling regime, the rate of heat transfer strongly depends on the nature of nucleation, which is difficult to predict. The type and the condition of the heated surface also affect the heat transfer. These complications made it difficult to develop theoretical relations for heat transfer in the nucleate boiling regime, and we had to rely on relations based on experimental data. The most widely used correlation for the rate of heat transfer in the nucleate boiling regime was proposed in 1952 by Rohsenow, and expressed as;
Abstract Computational fluid dynamics were used to simulate and study the heat transfer of both plain tube and helically ribbed tube for fire tube boiler. The operation condition was taken from Thermax Limited and used in a boundary condition accordingly. The result indicates the helically ribbed tube has higher heat transfer rate than plain tube.
Š 2017, IRJET
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3. CFD Analysis 3.1 Definition of Geometry The following section includes the design or the geometry of the Plain Tube and Helically Ribbed Tube. The CAD model is designed in CATIA V5R19 according to the specifications mentioned in the following Table 1. Table 1. Geometry parameters of the plain tube and helically ribbed tube.
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