This work presents the experimental and numerical investigations on the effectiveness of a small shell and tube heat exchanger for different coolant combinations. A numerical investigation is done ...using commercial computational tool, Fluent, to analyze heat transfer characteristics for the selected coolant combinations. The coolant combinations used consists of ethylene glycol (EG) and deionized water (DW) with varied percentages of the former. Accordingly, combination of ethylene glycol (EG) and deionized water viz, 60EG:40DW, 30EG:70DW and 20EG:80DW were used. The base fluids of EG and DW were used for the comparison of heat transfer characteristics, respectively with the selected coolant combination. For the numerical investigations, the CAD model of counter flow heat exchanger with 0 degree inclined baffles; with cold liquid flowing through the shell at the rate of 0.3 kg/s while hot liquid flows through the copper tubes at a flow rate of 0.3 kg/s was considered. Different combinations of shell-tube liquid are analyzed for identical initial and boundary conditions, keeping all other Fluent parameters the same. The temperature contours are generated for all the five cases. The temperature distribution for different shell-tube liquid combinations are compared for evaluating the effectiveness of heat exchange.
Improved heat exchange is ensured with higher temperature difference between inlet and outlet of shell/tube, and respective combination of shell and tube fluid is selected for industrial cooling applications. Results of CFD approach are validated with the experimental results and results are acceptable. From the results it is found that 60EG:40DW combination showed improved heat transfer characteristics compared to other combinations used. Among the different coolant combinations, 60EG:40DW showed higher heat transfer as indicated by higher temperature difference across both shell and tube sections followed by other combinations when compared to pure ethylene glycol. Shell outlet and Tube outlet temperature with 60EG:40DW increased by 227% and 105% respectively when compared with pure EG, due to improved heat exchange. Heat transfer rate, heat transfer coefficient with 60EG:40DW increased when compared to pure EG.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the past few decades, water and air were commonly used as working fluid to evaluate shell and tube heat exchanger (STHE) performance. This study was undertaken to estimate heat transfer ...coefficients and evaluate performance in the pilot-scale twisted tube-based STHE using the flue gas from biomass co-combustion as working fluid. Theoretical calculation along with experimental results were used to calculate the specific heat of flue gas. A simplified model was then developed from the integration of two heat transfer methods to predict the overall heat transfer coefficient without tedious calculation of individual heat transfer coefficients and fouling factors. Performance including water and trailer temperature, heat load, effectiveness, and overall heat transfer coefficient were jointly investigated under variable operating conditions. Results indicated that the specific heat of flue gas from co-combustion ranging between 1.044 and 1.338 kJ/kg·K while specific heat was increased by increasing flue gas temperature and decreasing excess air ratio. The developed mathematical model was validated to have relatively small errors to predict the overall heat transfer coefficient. A flue gas mass flow rate of 61.3–98.8 kg/h, a water flow rate of 13.7–14.1 L/min, and a parallel arrangement of two water-to-air heaters in an empty trailer were found to be optimal conditions for space heating purpose. In addition, a lower poultry litter feeding rate decreased heat loss of flue gas and increased heat gain of water, while a lower water flow rate also provided a lower maximum possible heat transfer rate with a higher actual heat transfer rate to quickly achieve heat equilibrium that ultimately improves the performance. This study demonstrates the possibility of collecting residual heat from the flue gas using the pilot-scale STHE system while outlining a systematic approach and process for evaluating its performance.
In this paper, fluid flow and heat transfer in the laboratory (small size) shell tube heat exchanger are analysed by computational fluid dynamic software. In this type of shell tube heat exchanger ...baffles with different angles of rotation: 00 (horizontal segmental baffle), 150 (from horizontal), 300, 450, 600, 750, 900 (vertical segmental baffle) is used. Effect of baffle orientation on shell tube heat exchanger performance is investigated. The flow domain is meshed by three-dimensional tetrahedral elements. The obtained result has a good agreement with the analytical method (Bell method) and experimental data in the literature. By comparing the pressure drop, heat transfer and heat transfer versus pressure drop (Q/ P) at same flow rate, the shell tube heat exchanger with orientation of (900) have better performance than other angles of baffle orientation. decrease pressure drop 26%, 4.1%, 17.6%, 24.42%, 14% rather than 150, 300, 450 ,600,750 ,00 angle of orientation respectively. That show have better performance than other angles of baffle orientation. So by reducing pressure drop with maintaining heat transfer rate, the operating cost reducing that can be best choice among other models.
An automated based-vision quality inspection system for Shell-Tube welding is presented in this paper in order to achieve nondestructive weld defect detection. The vision sensor is developed on the ...basis of the principle of laser triangulation. First, the composition and working principle of the vision-based quality inspection system are introduced, and meanwhile various defects may occur are described in detail. Then the image processing algorithm, as the most important part of online quality inspection system, is also represented. The image processing algorithm includes two parts: preprocessing and defect detection. In defect detection section, a novel method for determining and describing the position of undercut, which is based on the parameter equation of the circle to represent the position of the undercut, is presented. Last, two experiments are carried out for Shell-Tube heat exchanger and the experiments show that the image algorithm has high precision, strong robustness and can detect the defect accurately.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The vertical fixed shell–tube heat exchanger failed to work in one chemical plant, and the leakage of the heat exchanger tubes were found after the examination. To figure out the failure mechanism of ...the tubes, a series of investigations were performed including the specification verification, the visual examination, the analysis of the chemical composition, metallographic, scale layer composition, and the work fluid examination. The pits and cracks were observed on the tube end, which was welded to the upper sheet. It could be classified as the pitting corrosion and stress corrosion cracking of authentic stainless steel. Due to the substandard expansion process on the tube end, the crevices between the tube end and the upper tube sheet holes were not eliminated thoroughly. The high-temperature steam, mixed with the chloride ion and salts, entered into the crevices, and the chloride ion sufficiently gathered and absorbed on the surface of the tube end. Additionally, the stress was generated on the tube end from the operating pressure and welding process. The stress condition and high-temperature chloride condition on the tube end eventually led to the pitting corrosion and stress corrosion cracking.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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