Computational study of Staggered and Double Cross Flow Heat Exchanger

2017 ◽  
Vol 67 (4) ◽  
pp. 396
Author(s):  
Annur Srinivasan Krishnan ◽  
Palanivelu Gowtham
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Transfer Rate ◽  
Cross Flow ◽  
Flow Reynolds Number ◽  
Flow Heat ◽  
Shell And Tube ◽  
Double Cross

The preliminary findings of a comparative study of heat transfer rate and pressure drop between conventional staggered flow and double cross flow heat exchanger is reported. Excepting for the tube arrangements, the shell and tube dimensions, materials and inlet conditions are retained the same for the two configurations. While in the conventional arrangement, adjacent rows of tubes are normal only to the fluid flow in the shell, in the double cross-flow arrangement, they are normal to both fluid flow direction in the shell as well as to each other. Shell dimensions are 100 cm × 20 cm × 20 cm and tube outside and inside diameters are 1 cm and 0.8 cm. The shell and tube materials are steel and copper. Water and air were considered as tube and shell side fluids respectively, with an overall arrangement of parallel flow. The tube flow Reynolds number was fixed at 2200 and the shell flow Reynolds number was varied from 20 to 120 in the laminar regime and 360 to 600 in the turbulent zone. The study reveals that the proposed configuration gives a maximum increase of about 27 per cent in the heat transfer rate per unit pressure drop over the conventional one.

scholarly journals Investigation on fluid flow heat transfer and frictional properties of Al2O3 nanofluids used in shell and tube heat exchanger

2020 ◽  
Author(s):  
sreejesh S R chandran ◽  
Debabrata Barik ◽  
ANSALAM RAJ T G ◽  
Reby ROY
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Transfer Rate ◽  
Working Fluid ◽  
Flow Properties ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Frictional Properties ◽  
Flow Heat ◽  
Shell And Tube

Abstract Nanofluids are generally utilized in providing cooling, lubrication phenomenon, controlling the thermophysical properties of the working fluid. In this work, nanoparticles of Al2O3 are added to the base fluid which flows through the counter flow arrangement in a turbulent flow condition. The hot and cold fluids used are ethylbenzene and water respectively and have different velocities on both shell and tube side. This study emphasizes the analysis of flow properties, friction loss, and energy transfer in terms of heat using nanofluid in the heat exchanger. The heat transfer rate of present investigation with nanoparticle addition is 4.63% higher in comparision to Dittus Boelter correlation. Apart from this, the obtained friction factor is 0.0376 very much closer to Gnielinski and Blasius correlations. This investigation proved that appropriate nanoparticle additions and baffle inclinations have fabulous impact upon the performance of heat exchanger and its effectiveness.

scholarly journals Fluid flow consideration in fin-tube heat exchanger optimization

2010 ◽  
Vol 31 (3) ◽  
pp. 87-104 ◽  
Author(s):  
Piotr Wais
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Mass Flow ◽  
Cross Flow ◽  
Finned Tube ◽  
Tube Heat Exchanger ◽  
Flow Heat ◽  
The Cross ◽  
Fin Tube

Fluid flow consideration in fin-tube heat exchanger optimizationThe optimization of finned tube heat exchanger is presented focusing on different fluid velocities and the consideration of aerodynamic configuration of the fin. It is reasonable to expect an influence of fin profile on the fluid streamline direction. In the cross-flow heat exchanger, the air streams are not heated and cooled evenly. The fin and tube geometry affects the flow direction and influences temperature changes. The heat transfer conditions are modified by changing the distribution of fluid mass flow. The fin profile impact also depends on the air velocity value. Three-dimensional models are developed to find heat transfer characteristics between a finned tube and the air for different air velocities and fin shapes. Mass flow weighted average temperatures of air volume flow rate are calculated in the outlet section and compared for different fin/tube shapes in order to optimize heat transfer between the fin material and air during the air flow in the cross flow heat exchanger.

Thermal Efficiency of the Cross Flow Heat Exchangers

2006 ◽  
Author(s):  
Ahmad Fakheri
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Cross Flow ◽  
Algebraic Expression ◽  
Counter Flow ◽  
Optimum Heat ◽  
Flow Heat

The heat exchanger efficiency is defined as the ratio of the actual heat transfer in a heat exchanger to the optimum heat transfer rate. The optimum heat transfer rate, qopt, is given by the product of UA and the Arithmetic Mean Temperature Difference, which is the difference between the average temperatures of hot and cold fluids. The actual rate of heat transfer in a heat exchanger is always less than this optimum value, which takes place in an ideal balanced counter flow heat exchanger. It has been shown that for parallel flow, counter flow, and shell and tube heat exchanger the efficiency is only a function of a single nondimensional parameter called Fin Analogy Number. The function defining the efficiency of these heat exchangers is identical to that of a constant area fin with an insulated tip. This paper presents exact expressions for the efficiencies of the different cross flow heat exchangers. It is shown that by generalizing the definition of Fa, very accurate results can be obtained by using the same algebraic expression, or a single algebraic expression can be used to assess the performance of a variety of commonly used heat exchangers.

The Shell and Tube Heat Exchanger Efficiency and Its Relation to Effectiveness

2003 ◽  
Author(s):  
Ahmad Fakheri
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Optimum Heat ◽  
Flow Heat ◽  
Shell And Tube

The heat exchanger efficiency is defined as the ratio of the actual heat transfer in a heat exchanger to the optimum heat transfer rate. The optimum heat transfer rate, qopt, is given by the product of UA and the Arithmetic Mean Temperature Difference, which is the difference between the average temperatures of hot and cold fluids. The actual rate of heat transfer in a heat exchanger is always less than this optimum value, which takes place in a balanced counter flow heat exchanger. It is shown that for parallel flow, counter flow, and shell and tube heat exchanger the efficiency is only a function of a single nondimensional parameter called Fin Analogy Number. Remarkably, the functional dependence of the efficiency of these heat exchangers on this parameter is identical to that of a constant area fin with an insulated tip. Also a general algebraic expression as well as a generalized chart is presented for the determination of the efficiency of shell and tube heat exchangers with any number of shells and even number of tube passes per shell, when the Number of Transfer Units (NTU) and the capacity ratio are known. Although this general expression is a function of the number of shells and another nondimensional group, it turns out to be almost independent of the number of shells over a wide range of practical interest. The same general expression is also applicable to parallel and counter flow heat exchangers.

Experimental Study on Air Cooling via a Multiport Mesochannel Cross-Flow Heat Exchanger

2011 ◽  
Author(s):  
Sarbadaman Dasgupta ◽  
Faisal A. Siddiqui ◽  
Md. Abdul Quaiyum ◽  
Serena A. Al-Obaidi ◽  
Amir Fartaj
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Uniform Temperature ◽  
Flow Channels ◽  
Flow Heat

Researchers are moving forward to provide energy efficient, compact and inexpensive heat exchangers. Main focus is being deployed to the heat exchangers comprising narrow size flow channels such as mesochannels and microchannels for their augmented heat transfer characteristics, compactness and energy efficiency compared to conventional heat exchangers with the same heat exchange duty. Air to water cross-flow heat exchangers are encountered in many engineering applications. While numerous investigations were performed to characterize the heat transfer and fluid flow in mesochannels and microchannels, the literatures examining the air side heat transfer and flow behaviors in the cross-flow mesochannel heat exchangers are inadequate. In the current study air side heat transfer and flow characteristics of cross-flow cooling of air through a multiport slab mesochannel heat exchanger were investigated experimentally. The major components of experimental setup are the closed loop integrated thermal wind tunnel, liquid circulation network with heat add or removal system arrangement, sets of measuring instruments, data acquisition system, and multiport slab mesochannel heat exchanger as the test specimen. The multiport slab mesochannel heat exchanger consists of 15 finned aluminum slabs with 304 mm × 304 mm size frontal area and 100 mm flow length across the direction of air flow. Each slab contains 68 flow channels of 1mm circular diameter. Cold deionized (DI) water at a constant mass flow rate (0.0196 kg/s) was forced to flow through the mesochannels whereas the hot air at different velocities was allowed to pass through the finned passages of the heat exchanger core in cross-flow orientation. The inlet air temperature was changed in three levels (28°C, 33°C and 38°C) while maintaining a constant inlet water temperature of 8° C. The air velocity was varied in four steps (3.5m/s, 5.5m/s, 7.5m/s, and 9.5 m/s) at each temperature level. In the present study heat transfer and fluid flow key parameters such as heat transfer rate (Q˙), number of transfer units (NTU), effectiveness (ε), overall thermal resistance (Rtotal), and the air side Nusselt number (Nua) as well as Reynolds number (Rea) were examined in the region of the air side Reynolds number at the range of 972–2758, with a constant water side Reynolds number of 135. Heat balance performance of the experiment was found to be 4% for all operating conditions. The air side thermal resistance was found to be dominating over the overall thermal resistance ranging from 85% to 91% of the overall thermal resistance. The effect of air side Reynolds number on air side Nusselt number was examined and a general correlation of Nusselt number with Reynolds number was obtained as Nua = 0.3972(Rea)0.3766. The Nusselt number value was found to be higher in comparison with other research works for the corresponding Reynolds number range. The multiport mesochannel flat slab has offered uniform temperature distribution into the core. This uniform temperature distribution leads to higher heat transfer over standalone inline flow tube bank.

Numerical Investigation on Heat Transfer of Al2O3/Water Nanofluid in a Shell and Tube Heat Exchanger

2014 ◽  
Vol 591 ◽  
pp. 3-6
Author(s):  
M. Raja ◽  
R. Vijayan ◽  
R. Vivekananthan ◽  
M.A. Vadivelu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Numerical Investigation ◽  
Volume Concentration ◽  
Heat Transfer Characteristics ◽  
Tube Heat Exchanger ◽  
Transfer Characteristics ◽  
Shell And Tube ◽  
Suspended Nanoparticles

In the present work, the effect of nanofluid in a shell and tube heat exchanger was studied numerically. The effects of Reynolds number, volume concentration of suspended nanoparticles on the heat transfer characteristics were investigated using CFD software. Finally, the effect of the nanofluid on Shell and tube heat exchanger performance was studied and compared to that of a conventional fluid (i.e., water).

scholarly journals The Effect of Flowrate and Effectiveness on Theoretical Design and Thermal Characteristic of a GHE

2018 ◽  
Vol 225 ◽  
pp. 01023
Author(s):  
T.M. Yusof ◽  
M.F. Basrawi ◽  
A. Shahrani ◽  
H. Ibrahim
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Characteristic ◽  
Variable Parameter ◽  
Cross Flow ◽  
Outlet Temperature ◽  
Performance Study ◽  
Commercial Unit ◽  
Hot Climate ◽  
Flow Heat

Ground heat exchanger is an exciting technique to reduce energy consumption in building especially in hot climate countries. Implementation of GHE for commercial unit in Malaysia is almost none in record. Thus, performance study of the GHE in Malaysia is crucial to be conducted either experimentally or numerically. Therefore, this paper presents the performance of GHE in term of effectiveness, outlet temperature and rate of heat transfer based on mathematical model. The model is developed based on cross flow heat exchanger with one fluid unmixed. There are two variable parameter used in the analysis which is effectiveness and flowrate of the air for 25 meter length of a PVC pipe. Three effectiveness values which is 0.8, 0.9 and 0.99 have been analysed in this study. Meanwhile, flowrate of air is ranging from 0.02 to 0.2 kg/s. Results show that flowrate at 0.02 kg/s gives great temperature reduction in the pipe compared with higher flowrate. However, flowrate of 0.2 kg/s produces higher cooling potential. Characteristic of the GHE for the rate of heat transfer with 80, 90 and 99 percent effectiveness also have been developed and it has been found that effectiveness of 0.9 provide good combination between flowrate and the rate of heat transfer for 25 meter length of the pipe

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