scholarly journals Thermal Analysis and Performance Evaluation of Triple Concentric Tube Heat Exchanger

2019 ◽  
Vol 8 (6) ◽  
pp. 3898-3905
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Rate Variation ◽  
Tube Heat Exchanger

Triple concentric-tube exchanger (TCTHE) is an improved version of double concentric tube heat exchanger (DCTHE). Introducing an intermediate tube to a DCTHE provides TCTHE and enhances the heat transfer performance. Recognizing the need of experimental results, extremely scarce in the literature and essential to validate theoretical analyses, the aim of this work is to investigate thermal behavior of TCTHE. The present study includes design, development and experimental analysis of TCTHE for oil (ISO VG 22) cooling application required for industrial purposes. It comprises of water (cooling fluid) flowing through innermost tube as well as outer annulus and oil (hot fluid) flows through inner annulus. The experimental studies of the temperature distribution for three fluids along the length and heat transfer characteristics for TCTHE under insulated condition for counter current flow mode are carried out and discussed. The effect of change in oil (hot fluid) temperatures is analyzed keeping water inlet temperatures same at various operating conditions. The experiments have been conducted by varying flow rate of one of the fluids at a time and keeping other two fluid flow rates constant. The results are expressed in terms of temperature variation for all three fluids along the length. The effect of change in hot fluid inlet temperature is expressed in terms of heat transfer rate variation with respect to Reynolds number. The variation of non-dimensional parameters as temperature effectiveness and thermal conductance with respect to Reynolds number is also presented in this paper. Theoretical studies are carried out for evaluation of heat transfer rate using empirical correlations. Experimental validation is carried out for degree of cooling at different Reynolds numbers with theoretical analysis

Performance Evaluation of Tube-in-Tube Heat Exchanger Using Nanofluids

2015 ◽  
Vol 787 ◽  
pp. 72-76 ◽  
Author(s):  
V. Naveen Prabhu ◽  
M. Suresh
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Element Analysis ◽  
Tube Heat Exchanger

Nanofluids are fluids containing nanometer-sized particles of metals, oxides, carbides, nitrides, or nanotubes. They exhibit enhanced thermal performance when used in a heat exchanger as heat transfer fluids. Alumina (Al2O3) is the most commonly used nanoparticle due to its enhanced thermal conductivity. The work presented here, deals with numerical simulations performed in a tube-in-tube heat exchanger to study and compare flow characteristics and thermal performance of a tube-in-tube heat exchanger using water and Al2O3/water nanofluid. A local element-by-element analysis utilizing e-NTU method is employed for simulating the heat exchanger. Profiles of hot and cooling fluid temperatures, pressure drop, heat transfer rate along the length of the heat exchanger are studied. Results show that heat exchanger with nanofluid gives improved heat transfer rate when compared with water. However, the pressure drop is more, which puts a limit on the operating conditions.

Numerical Study of Shellside Performance of Heat Transfer and Flow Resistance for Heat Exchanger with Trefoil-Hole Baffles

2012 ◽  
Vol 557-559 ◽  
pp. 2141-2146
Author(s):  
Yong Hua You ◽  
Ai Wu Fan ◽  
Chen Chen ◽  
Shun Li Fang ◽  
Shi Ping Jin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Pressure Loss ◽  
Transfer Rate ◽  
Numerical Study ◽  
Shell Side ◽  
Tube Heat Exchanger

Trefoil-hole baffles have good thermo-hydraulic performances as the support of heat pipes, however the published research paper is relatively limited. The present paper investigates the shellside thermo-hydraulic characteristics of shell-and-tube heat exchanger with trefoil-hole baffles (THB-STHX) under turbulent flow region, and the variations of shellside Nusselt number, pressure loss and overall thermo-hydraulic performance (PEC) with Reynolds number are obtained for baffles of varied pitch with the numerical method. CFD results demonstrate that the trefoil-hole baffle could enhance the heat transfer rate of shell side effectively, and the maximal average Nusselt number is augmented by ～2.3 times that of no baffle, while average pressure loss increases by ～9.6 times. The PEC value of shell side lies in the range of 16.3 and 73.8 kPa-1, and drops with the increment of Reynolds number and the decrement of baffle pitch, which indicates that the heat exchanger with trefoil-hole baffles of larger pitch could generate better overall performance at low Reynolds number. Moreover, the contours of velocity, turbulent intensity and temperature are presented for discussions. It is found that shellside high-speed jet, intensive recirculation flow and high turbulence level could enhance the heat transfer rate effectively. Besides good performance, THB-STHXs are easily manufactured, thus promise widely applied in various industries.

scholarly journals CFD Study Based on Effect of Employing the Single-Walled Carbon Nanotube (SWCNT) and Graphene Quantum Dots (GQD) Nanoparticles and a Particular Fin Configuration on the Thermal Performance in the Shell and Tube Heat Exchanger

CFD letters ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 37-60
Author(s):  
Mohammadreza Hasandust Rostami ◽  
Barat Ghobadian ◽  
Gholamhassan Najafi ◽  
Ali Motevali ◽  
Nor Azwadi Che Sidik
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Concentration ◽  
Working Fluid ◽  
Tube Heat Exchanger ◽  
Average Temperature

In this research, the thermal attributes of shell and finned tube heat exchanger such as thermal efficiency, pressure drop, heat transfer rate and average temperature in the tube side of heat exchanger with using the different volume concentration of nanoparticles (SWCNT and Graphene quantum dot) at the various Reynolds number by applying either fin blades and without fin blades have been conducted numerically. In this heat exchanger the hot fluid or nanofluid flows in the tube section and cold fluid or pure water moves in the shell side. As regarding to results obtained the majority of thermal characteristics like heat transfer rate, pressure drop and effectiveness enhanced with augmentation of Reynolds number and increasing of volume concentration of nanofluids to 1% volumetric of working fluid whereas at the higher volume concentrations of nanoparticles (upper from 1% volumetric) the thermal properties of heat exchanger decreased generally. Also pressure drop intensifies with increment of Reynolds number and volume concentration of nanoparticles that at higher Reynolds number the effects of nanoparticles on the pressure drop were more noticeable. The average temperature of heat exchanger in the end section of inside tubes increased with augmentation of Reynolds number and nanoparticles. Finally, according to the results obtained in this study, most impression on the thermal attributes enhancement was found by employing of finned tubes compared to other factor which this factor increased heat transfer rate of heat exchanger by almost 188% also the effects of nanoparticles at the high levels of volume concentration especially for 5% of SWCNT nanoparticle on the pressure drop obtained about 80% compared to the base fluid.

Prediction of Non-Uniform Frost Distribution on a Fin Tube Heat Exchanger

2013 ◽  
Author(s):  
Jieun Hwang ◽  
Keumnam Cho
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Heat Pump ◽  
Transfer Rate ◽  
Volume Flow Rate ◽  
Local Data ◽  
Tube Heat Exchanger ◽  
Side Pressure ◽  
Fin Tube

Heat exchanger experiences frost on its surface when it operates below 0°C under heating condition of the heat pump. Since frost blocks air flow through the fin tube heat exchanger, it increases air-side pressure drop and deteriorates heat transfer rate of the heat exchanger. Prediction of the frost profiles on the heat exchanger is needed to minimize the unfavorable effect on the heat exchanger by frost. The present study predicts non-uniform frost distribution on the surface of fin-tube heat exchanger and shows its accuracy by comparing with measured profiles. Fin and tube heat exchanger for heat pump was considered for the frost prediction under practical refrigerant and air conditions. Non-uniform frost pattern was predicted by using segment by segment method of the heat exchanger. Heat transfer rate and exit temperature of air and refrigerant for each segment were calculated by applying ε-NTU method. Air volume flow rate in the front of the heat exchanger was decreased as frost goes on. It was utilized for the prediction of the frost formation. Numerically predicted results were compared with measured local data. They agreed within ±10.4% under the ISO 5151 condition.

scholarly journals Enhancing Heat Transfer in Tube Heat Exchanger by Inserting Discrete Twisting Tapes with Different Positions

2019 ◽  
Vol 25 (8) ◽  
pp. 39-51
Author(s):  
Nassr Fadhil Hussein ◽  
Abdulrahman Shakir Mahmood
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Constant Heat Flux ◽  
Vertical Position ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Twisted Tapes ◽  
Maximum Heat Transfer

Enhancement of heat transfer in the tube heat exchanger is studied experimentally by using discrete twisted tapes. Three different positions were selected for inserting turbulators along tube section (horizontal position by α= 00, inclined position by α= 45 0 and vertical position by α= 900). The space between turbulators was fixed by distributing 5 pieces of these turbulators with pitch ratio    PR = (0.44). Also, the factor of constant heat flux was applied as a boundary condition around the tube test section for all experiments of this investigation, while the flow rates were selected as a variable factor (Reynolds number values vary from 5000 to 15000). The results show that using discrete twisted tapes enhances the heat transfer rate by about 60.7-103.7 % compared with plane tube case. Also, inserting turbulators with inclined position offers maximum heat transfer rate by 103.7%.  

scholarly journals Design and Analysis of double- stacked Heat Exchanger for Brewery Application

2020 ◽  
Vol 9 (1) ◽  
pp. 1793-1798
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Working Fluid ◽  
Support Weight ◽  
Tube Heat Exchanger ◽  
Shell And Tube

A heat exchanger is a device intensively used for enhancing the transfer of heat energy between two or more working fluids at different temperature, which are in thermal contact. The optimal design and efficient operation of heat exchanger and heat transfer network are of a great significance in any of the process industry. The heat transfer efficiency depends on both design of heat exchanger and property of working fluid. From various types of heat exchanger, the double stacked shell and tube heat exchanger with straight tube and single pass is to be under study. Here the redesign of heat exchanger takes place with the key objectives of optimizing the pressure drop, optimizing the heat transfer rate and reducing the saddle support weight used for cooling purpose in brewery application. The design calculations are carried out using the Kerns and Bell Delwar method and other important parameters dealing with material selection and geometries are also taken into consideration. FEA analysis for optimizing the saddle support weight is carried out using Dassault systeme’s Solidworks while the CFD analysis for optimizing pressure drop and heat transfer rate is carried out using Dassault systeme’s Solidworks analysis software and the design and working of Shell and tube heat exchanger is determined in terms of variables such as pressure ,temperature ,mass flow rate ,flow rate ,energy input output that are of particular interest in Shell and tube heat exchanger analysis.

Heat Transfer Enhancement in a Double Pipe Heat Exchanger by Insertion of Propeller-Type Swirl Generators

2010 ◽  
Author(s):  
Khwanchit Wongcharee ◽  
Somsak Pethkool ◽  
Chinaruk Thianpong
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Friction Factor ◽  
Operating Conditions ◽  
Interval Length ◽  
Tube Heat Exchanger ◽  
Nusselt Numbers ◽  
Plain Tube

This paper describes an experimental study of turbulent convective heat transfer and flow friction characteristics in a double tube heat exchanger equipped with propellers (2 blade-type). The propellers are used as the decaying swirl generators in the inner tube. The experiments were performed using the propellers with four different interval lengths (l = 1D, 2D, 3D and 4D where D is diameter of the inner tube), for the Reynolds number ranging from 5000 to 32,000, using water with temperature of 27°C and 70°C as cold and hot working fluids, respectively. The data of the tube equipped with the propellers are reported together with those of the plain tube, for comparison. The obtained results demonstrate that the heat transfer rate in term of Nusselt number (Nu) and friction factor (f) in the tube with propellers are higher than those in the plain tube at the similar operating conditions. This is due to the chaotic mixing and efficient interruption of thermal boundary layer caused by the propellers. In addition, the Nusselt number and friction factor in the tube fitted with the propellers increase as the interval length decreases. Depending on Reynolds number and interval length, Nusselt numbers and friction factors in the tube fitted with the propellers are augmented to 1.95 to 2.3 times and 5.8 to 13.2 times of those in the plain tube. In addition, the correlations of the Nusselt number (Nu) and the friction factor (f) for tube fitted with the propellers are reported and the performance evaluation to access the real benefits of using the turbulators is also determined.

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