scholarly journals Increasing the Thermal Efficiency of Double Tube Heat Exchangers by Using Nano Hybrid

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Mohamad Hosein Barzegar ◽  
Mohamad Fallahiyekta
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cold Water ◽  
Hybrid Nanoparticles ◽  
Hybrid Nanofluid ◽  
Twisted Tape ◽  
Overall Heat Transfer Coefficient ◽  
Turbulent Flow Regime ◽  
Double Pipe

In this study overall heat transfer in a double pipe heat exchanger fitted with twisted-tape elements and hybrid nanofluid were studied experimentally. Hybrid nanoparticles with a diameter of 20nm and a concentration of 1% (w/w) were prepared. The effects of temperature, mass flow rate, concentration of nanoparticles on the overall heat transfer coefficient and heat transfer changes in the turbulent flow regime were investigated. The results showed that when both of twisted tape and nanofluid have been used, heat transfer coefficient was about 40 percent higher than when they were not used. The experimental results also showed that 1% Al2O3/CuO nanofluid with twisted tape has slightly higher heat transfer when compared to 1% hybrid nanofluid without twisted tape. Neural networks used for modeling the system. The dependency of overall heat transfer coefficient of nanofluid (OHTCNF) on Reynolds number have depicted. The correlation coefficient for all data 0.98 is the successful prediction is shown. In this experimental work, nanoparticles were dispersed in hot current and cold water absorbed heat from hot nanofluid, so this system could be a good candidate for using in food industries, because at the end of this process there isn't any needs of extracting nanoparticles from the cold current. The heat transfer rate from the heating fluid was calculated by some known equations.

Energy Efficient Hybrid Nanofluids for Tubular Cooling Applications

2014 ◽  
Vol 592-594 ◽  
pp. 922-926 ◽  
Author(s):  
Devasenan Madhesh ◽  
S. Kalaiselvam
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Concentration ◽  
Thermal Characteristics ◽  
Hybrid Nanofluid ◽  
Tubular Heat Exchanger ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Hybrid Nanofluids

Analysis of heat transfer behaviour of hybrid nanofluid (HyNF) flow through the tubular heat exchanger was experimentally investigated. In this analysis the effects of thermal characteristics of forced convection, Nusselt number, Peclet number, and overall heat transfer coefficient were investigated.The nanofluid was prepared by dispersing the copper-titania hybrid nanocomposite (HyNC) in the water. The experiments were performed for various nanoparticle volume concentrations addition in the base fluid from the range of 0.1% to 1.0%. The experimental results show that the overall heat transfer coefficient was found to increases maximum by 30.4%, up to 0.7% volume concentration of HyNC.

scholarly journals Experimental and CFD analysis on heat transfer and fluid flow characteristic of a tube equipped with variable pitch twisted tape

2019 ◽  
Vol 116 ◽  
pp. 00058
Author(s):  
Sagar Paneliya ◽  
Parth Prajapati ◽  
Umang Patel ◽  
Ingit Trivedi ◽  
Anshu Patel ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Stainless Steel ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Twisted Tape ◽  
Variable Pitch ◽  
Overall Heat Transfer Coefficient ◽  
Constant Pitch ◽  
Computational Fluid Dynamics Cfd

In this paper, we report an experimental and Computational Fluid Dynamics (CFD) investigation on the overall heat transfer coefficient, friction factor and effectiveness of a tube equipped with classic and variable twisted tape inserts. Constant (Y = 4.0) and variable pitch twisted inserts (Y = 4-3-4) made of Stainless Steel and Aluminium were used during the experiments due to their ease in machinability. Resistance thermometers were used to measure temperature of the working fluid at the inlet and outlet of the test section. It was observed that the twisted tape in the tube imposes the turbulence in the fluid and enhances the heat transfer due to swirling flow. The results showed that the overall heat transfer coefficient and effectiveness of aluminium variable pitch twisted tape were higher than stainless steel inserts. The experimental data obtained were validated using Computational Fluid Dynamics (CFD) simulations. The constant pitch inserts for aluminium and stainless steel showed an enhancement of 67.54% and 66.65% as compared to plain tube. Whereas aluminium variable pitch inserts showed an enhancement of overall heat transfer coefficient by 18.15% as compared to constant pitch insert and stainless-steel variable pitch insert showed enhancement of 15.25% as compared to constant pitch insert.

Experimental Analysis on Heat Transfer Enhancement of Double Pipe Heat Exchanger Using Alumina/Water Nanofluid and Baffled Twisted Tape Inserts

2015 ◽  
Vol 752-753 ◽  
pp. 458-465
Author(s):  
P.C. Sreekumar ◽  
K. Krishnamoorthy ◽  
R. Ratheesh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Twist Ratio ◽  
Double Pipe ◽  
Pipe Heat

Heat transfer augmentation techniques ultimately results in the reduction of thermal resistance in a conventional heat exchanger by generating higher convective heat transfer coefficient. Present study with the use of Alumina (Al2O3)/water nanofluid and baffled twisted tape inserts in double pipe heat exchanger as compound augmentation technique. Experiments were conducted to evaluate the heat transfer coefficient and friction factor for the flow through the inner tube of heat exchanger in turbulent flow range (8000<Re<60000). The effect of rectangular, circular, triangular baffled twisted tape having twist ratio (y/w) 4.2 and twisted tapes without baffles of twist ratio (y/w) 4.2 and 5.2 were studied. Experiments were conducted for both water and 0.1% volume concentration Alumina/water nanofluid. It is found that the enhancement of heat transfer coefficient by using rectangular baffled twisted tape and nanofluid is about 20%. Performance evaluation criteria were found for water and nanofluid and it was observed that rectangular baffled twisted tape performs better than other twisted tapes.

scholarly journals Experimental Heat Transfer using Insert for Nusselt Number Enhancement

2020 ◽  
Vol 9 (8) ◽  
pp. 138-144
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Twisted Tape ◽  
Overall Heat Transfer Coefficient ◽  
Experimental Heat ◽  
Increase With Increase ◽  
Twist Ratio ◽  
Laminar And Turbulent Flow

Various heat transfer and its enhancement techniques are found in literature. Many researchers have focused on such topics typically in last decade of last century. The paper deals with experimental work of the passive techniques which do not require direct application of external power, whereas the active techniques require an. Exact method and system used for research from 1964 till around 2000 is presented. A case study of twisted tape of Y as 4.2 and 5.2. It is seen that overall heat transfer coefficient is a function of Reynolds number. .It is noticed that on the tube side the flow conditions have included both laminar and turbulent flow. Graph presents shows heat transfer data for both twisted tapes. It can be seen that the overall heat transfer coefficient in general increase with increase in Reynolds number. For a given Reynolds number the overall heat transfer coefficient increase with decrease in twist ratio i.e. tape with tighter twist. Also friction factor increase with decreases in the twist ratio

scholarly journals Effect of Twisted-Tape Turbulators and Nanofluid on Heat Transfer in a Double Pipe Heat Exchanger

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Heydar Maddah ◽  
Reza Aghayari ◽  
Morshed Farokhi ◽  
Shabnam Jahanizadeh ◽  
Khatere Ashtary
Keyword(s):  
Heat Transfer ◽  
Titanium Dioxide ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Flow Rate ◽  
Twisted Tape ◽  
Double Pipe ◽  
Pipe Heat

Heat transfer and overall heat transfer in a double pipe heat exchanger fitted with twisted-tape elements and titanium dioxide nanofluid were studied experimentally. The inner and outer diameters of the inner tube were 8 and 16 mm, respectively, and cold and hot water were used as working fluids in shell side and tube side. The twisted tapes were made from aluminum sheet with tape thickness (d) of 1 mm, width (W) of 5 mm, and length of 120 cm. Titanium dioxide nanoparticles with a diameter of 30 nm and a volume concentration of 0.01% (v/v) were prepared. The effects of temperature, mass flow rate, and concentration of nanoparticles on the overall heat transfer coefficient, heat transfer changes in the turbulent flow regimeRe≥2300, and counter current flow were investigated. When using twisted tape and nanofluid, heat transfer coefficient was about 10 to 25 percent higher than when they were not used. It was also observed that the heat transfer coefficient increases with operating temperature and mass flow rate. The experimental results also showed that 0.01% TiO2/water nanofluid with twisted tape has slightly higher friction factor and pressure drop when compared to 0.01% TiO2/water nanofluid without twisted tape. The empirical correlations proposed for friction factor are in good agreement with the experimental data.

scholarly journals Design and Construction of a Double Pipe Heat Exchanger for Laboratory Application

2020 ◽  
Vol 5 (11) ◽  
pp. 1301-1306
Author(s):  
C. E. Ebieto ◽  
R. R. Ana ◽  
O. E. Nyong ◽  
E. G. Saturday
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Engineering Students ◽  
Counter Flow ◽  
Flow Configuration ◽  
Overall Heat Transfer Coefficient ◽  
Double Pipe ◽  
Pipe Heat

Engineering education is incomplete without laboratory practices. One of such laboratory equipment necessary for all engineering students to have hands-on in the course of their undergraduate studies is the heat exchanger. This work presents the detailed design and construction of a laboratory type double pipe heat exchanger that can be used both in the parallel and counter flow configuration. The heat exchanger was constructed using galvanized steel for both the tube and shell. Experiments were designed and carried out to test the performance of the heat exchangers. The heat exchanger performance characteristics (logarithm mean temperature difference (LMTD), heat transfer rate, effectiveness, and overall heat transfer coefficient) were obtained and compared for the two configurations. The LMTD tends to be relatively constant as the flow rate was increased for both the parallel and counter-flow configuration but with a higher value for the parallel flow configuration. The heat exchanger has a higher heat transfer rate, effectiveness, and overall heat transfer coefficient and therefore has more performance capability for the counter-flow configuration. The overall heat transfer coefficient increased as the flow rate increased for both configurations. Importantly, as a result of this project, Mechanical Engineering students can now have hands-on laboratory experience on how the double pipe heat exchanger works.

scholarly journals Design, Fabrication and Performance Evaluation of a Shell and Tube Heat Exchanger for Practical Application

2020 ◽  
Vol 5 (8) ◽  
pp. 835-845
Author(s):  
Bashiru Abdulmumuni ◽  
Adedeji Mathew Ayoade ◽  
Ologunye Opeyemi Buhari ◽  
Azeez Rasheed Olatunde ◽  
Fanifosi Johnson Olaniyi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Cold Water ◽  
Hot Water ◽  
Feed Water ◽  
Capacity Ratio ◽  
Overall Heat Transfer Coefficient ◽  
Fouling Factor

A heat exchanger is a device used to transfer thermal energy between two or more fluids, at different temperatures in thermal contact. This paper focuses on a shell-and-tubes heat exchanger that involves two fluids (hot water and cold water) in contact with each other while the cold water flows through the tubes and hot water through the shell. Heat exchangers have special and practical applications in the feed water cooler in the process industries, power plants, chemical plants, refineries, process applications as well as refrigeration and air conditioning industry. The design calculations were carried out to determine the specifications of essential parameters for the development of the heat exchanger, data generated from the theoretical formulae were used to fabricate the heat exchanger using some locally available and durable materials, and the performance of the system was evaluated. Some of the parameters evaluated include heat duty, capacity ratio, effectiveness, overall heat transfer coefficient, and fouling factor. The heat exchanger was tested under various flow conditions and the results obtained were as follows; cold water inlet temperatures of (26, 26, 26, 27and 27) ºC increased to (59, 44, 39, 47 and 35) ºC after (10, 7½, 6½  8,  and 6) minutes and the hot water temperatures decreased from (100, 80, 75, 87 and 73) ºC to (73, 59, 55, 62 and 50) ºC, respectively. The design data and test data were compared in terms of the heat duty, capacity ratio, effectiveness, overall heat transfer coefficient, and fouling factor, the deviation is found to be 22.87%, 13.99%, 8.98%, 43.30%, and 43.30% respectively. The results obtained proved that the heat exchanger was effective, reliable and provides a good technical approach to evaluate the thermal performance of the heat exchanger and useful in conducting heat and mass transfer practical in thermodynamics laboratory.

scholarly journals A numerical model and validation of phase change material integrated thermoelectric radiant cooling panel

2019 ◽  
Vol 111 ◽  
pp. 01001
Author(s):  
Hansol Lim ◽  
Hye-Jin Cho ◽  
Seong-Yong Cheon ◽  
Soo-Jin Lee ◽  
Jae-Weon Jeong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Numerical Model ◽  
Surface Temperature ◽  
Phase Change ◽  
Transfer Coefficient ◽  
Phase Change Material ◽  
Overall Heat Transfer Coefficient ◽  
Radiant Cooling ◽  
Change Material

A phase change material based radiant cooling panel with thermoelectric module (PCM-TERCP) is proposed in this study. It consists of two aluminium panels, and phase change materials (PCMs) sandwiched between the two panels. Thermoelectric modules (TEMs) are attached to one of the aluminium panels, and heat sinks are attached to the top side of TEMs. PCM-TERCP is a thermal energy storage concept equipment, in which TEMs freeze the PCM during the night whose melting temperature is 16○C. Therefore, the radiant cooling panel can maintain a surface temperature of 16◦C without the operation of TEM during the day. Furthermore, it is necessary to design the PCM-TERCP in a way that it can maintain the panel surface temperature during the targeted operating time. Therefore, the numerical model was developed using finite difference method to evaluate the thermal behaviour of PCM-TERCP. Experiments were also conducted to validate the performance of the developed model. Using the developed model, the possible operation time was investigated to determine the overall heat transfer coefficient required between radiant cooling panel and TEM. Consequently, the results showed that a overall heat transfer coefficient of 394 W/m2K is required to maintain the surface temperature between 16○C to 18○C for a 3 hours operation.

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