Derive The NTU-Effectiveness Formula For The Double Pipe Heat Exchanger In Parallel Flow Arrangement

2017 ◽  
pp. 1
Author(s):  
Elmuataz Moftah ◽  
Ahmad Abdelaly ◽  
Ali Gebriel ◽  
Wahbe Pohwess
Keyword(s):  
Heat Exchanger ◽  
Parallel Flow ◽  
Double Pipe ◽  
Pipe Heat

scholarly journals Thermal Performance Evaluation of a Double Pipe Heat Exchanger Installed in a Biomass Gasification System

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Nwabunwanne Nwokolo ◽  
Patrick Mukumba ◽  
KeChrist Obileke
Keyword(s):  
Heat Exchanger ◽  
Heat Recovery ◽  
Cooling Water ◽  
Biomass Gasification ◽  
Industrial Applications ◽  
Parallel Flow ◽  
Operating Conditions ◽  
Exit Point ◽  
Double Pipe ◽  
Pipe Heat

Heat exchangers are widely used for heat recovery purposes in many industrial applications such as gasification systems. In a biomass gasification system situated at Melani village in Eastern Cape of South Africa, a significant quantity of heat energy is lost during syngas cooling. Thus, a heat exchanger was constructed and installed in the gasification system for the purpose of heat recovery. Therefore, the aim of this study is to evaluate the performance of the heat exchanger under variable operating conditions for counterflow and parallel flow configurations. The experimental investigation was carried out on a double pipe heat exchanger as the downdraft gasifier system operated on a wood consumption rate of 180 kg/h. The heat exchanger was installed at the exit point of the syngas in the gasifier, and water served as the cooling fluid. Inlet and outlet temperatures of the hot syngas and cooling water (fluids) were measured using thermocouples at variable flow rates. Experimental data were processed using energy equations to determine vital performance parameters (overall heat transfer coefficient, effectiveness, and log mean temperature difference). The findings showed that optimum heat exchanger effectiveness of 0.55 was determined at a mass flow rate of 0.07 kg/s. In addition, counterflow configuration was found to be approximately 14% more effective than the parallel flow configuration. This is attributed to the relative direction of the fluids in the configurations of both flows. The study recommends that double pipe heat exchanger is suitable for recovering heat from the gasification system.

scholarly journals Experimental and CFD Analysis of GW70 based Cu Nanofluids in a Parallel Flow Heat Exchanger

2021 ◽  
Vol 10 (4) ◽  
pp. 106-110
Author(s):  
M.L.R. Chaitanya Lahari ◽  
◽  
P.H.V. Sesha Talpa Sai ◽  
K.V. Sharma ◽  
K.S. Narayanaswamy ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Mass Flow ◽  
Parallel Flow ◽  
Hot Water ◽  
Cfd Analysis ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Double Pipe ◽  
Pipe Heat

The Nusselt number, overall heat transfer, and convective heat transfer coefficients of glycerol-water-based Cu nanofluids flowing in a parallel flow double pipe heat exchanger are estimated using CFD analysis. Single-phase fluid approach technique is used in the analysis. Ansys 19.0 workbench was used to create the heat exchanger model. Heat transfer tests with nanofluids at three flow rates (680<Re<1900) are carried out in a laminar developing flow zone. For testing, a 500 mm long concentric double pipe heat exchanger with tube dimensions of ID=10.2 mm, OD= 12.7 mm, and annulus dimensions of ID=17.0 mm, OD= 19.5 mm is employed. Copper is utilized for the tube and annulus material. This study employed three-particle volume concentrations of 0.2 percent, 0.6 percent, and 1.0 percent. The mass flow rates of hot water in the tube are 0.2, 0.017, and 0.0085 kg/s, while the mass flow rates of nanofluids in the annulus are 0.03, 0.0255, and 0.017 kg/s. The average temperature of nanofluids is 36°C, whereas hot water is 58°C. In comparison to base liquid, the overall heat transfer coefficient and convective HTC of 1.0 percent copper nanofluids at 0.03 kg/s are raised by 26.2 and 46.2 percent, respectively. The experimental findings are compared to CFD values, and they are in close agreement.

scholarly journals Numerical and experimental investigation of alumina-based nanofluid effects on double-pipe heat exchanger thermal performances

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
A. Bendaraa ◽  
My. M. Charafi ◽  
A. Hasnaoui
Keyword(s):  
Heat Exchanger ◽  
Volume Fraction ◽  
Convective Heat Transfer Coefficient ◽  
Deionized Water ◽  
Comsol Multiphysics ◽  
Exchange Coefficient ◽  
The Subject ◽  
Double Pipe ◽  
Pipe Heat ◽  
Thermoelectric Power Plant

AbstractIn this study, we investigate the thermal behaviour of nanofluids in a double-pipe heat exchanger. It is about a counterflow configuration, designed to cool a lubrication unit of a thermoelectric power plant. The subject of this work is to evaluate the thermal performances of the exchanger by using a nanofluid based on alumina suspension comparing with deionized water. In order to evaluate the thermal performance of the studied configuration, we carried out numerical experiments in an application developed on COMSOL Multiphysics environment, these experiments are utilized to show the feasibility of this application. As result, we found that the nanofluid with an increase in its volume fraction leads to an increase in the overall exchange coefficient, the convective heat transfer coefficient, as well as the efficiency and the power of the exchanger. It is noted that an increase of 1% in volume fraction, can enhance the overall exchange coefficient, the power and the effectiveness of the exchanger by 17.62%, 1.473% and 10.80% respectively. Besides, it is noted that the increase in the concentration of nanofluids leads to a narrowing of the pinch points of the inlet and outlet temperatures, which means that nanofluids are more efficient in cooling temperatures than conventional fluids.

scholarly journals Investigation of Overlapped Twisted Tapes Inserted in a Double-Pipe Heat Exchanger Using Two-Phase Nanofluid

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1656 ◽  
Author(s):  
Mehdi Ghalambaz ◽  
Hossein Arasteh ◽  
Ramin Mashayekhi ◽  
Amir Keshmiri ◽  
Pouyan Talebizadehsardari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Evaluation Criterion ◽  
Twisted Tape ◽  
Performance Evaluation Criterion ◽  
Twisted Tapes ◽  
Double Pipe ◽  
Pipe Heat

This study investigated the laminar convective heat transfer and fluid flow of Al2O3 nanofluid in a counter flow double-pipe heat exchanger equipped with overlapped twisted tape inserts in both inner and outer tubes. Two models of the same (co-swirling twisted tapes) and opposite (counter-swirling twisted tapes) angular directions for the stationary twisted tapes were considered. The computational fluid dynamic simulations were conducted through varying the design parameters, including the angular direction of twisted tape inserts, nanofluid volume concentration, and Reynolds number. It was found that inserting the overlapped twisted tapes in the heat exchanger significantly increases the thermal performance as well as the friction factor compared with the plain heat exchanger. The results indicate that models of co-swirling twisted tapes and counter-swirling twisted tapes increase the average Nusselt number by almost 35.2–66.2% and 42.1–68.7% over the Reynolds number ranging 250–1000, respectively. To assess the interplay between heat transfer enhancement and pressure loss penalty, the dimensionless number of performance evaluation criterion was calculated for all the captured configurations. Ultimately, the highest value of performance evaluation criterion is equal to 1.40 and 1.26 at inner and outer tubes at the Reynolds number of 1000 and the volume fraction of 3% in the case of counter-swirling twisted tapes model.

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