Experimental Investigation of Nanofluid Heat Transfer in a Plate Heat Exchanger

2012 ◽  
Author(s):  
Matthew Taws ◽  
Cong Tam Nguyen ◽  
Nicolas Galanis ◽  
Iulian Gherasim
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Hydraulic Characteristics ◽  
Transfer Enhancement ◽  
Cold Side ◽  
Particle Volume ◽  
Nusselt Numbers ◽  
Turbulent Transition ◽  
Corrugated Plates ◽  
Two Fluid

An experimental study was carried out to determine the forced convective heat transfer and hydraulic characteristics of a chevron-type two-channel industrial PHE when used with a nanofluid. The PHE is composed of two fluid passages formed by three corrugated plates, which have a herringbone pattern and the corrugations are of a trapezoidal shape. Heated water is used on the hot side. On the cold side a mixture of 29nm-diameter CuO nanoparticles in suspension in water is forced. Collected data for the nanofluid side covers two particle volume fractions, 2% and 4.65%, and the range of Reynolds number up to 1000. Results have shown that, for a given Reynolds number, CuO-water nanofluid clearly exhibits a higher friction factor compared to that of water. Calculated Nusselt numbers have shown no significant heat transfer enhancement when using the 2% nanofluid. A decrease of heat transfer was even observed with the 4.65% nanofluid. The laminar-turbulent transition was also observed for the nanofluids studied.

Endwall Heat Transfer Enhancement Around Cylinders With a Wall-Mounted Vortex Generator Pair

2017 ◽  
Author(s):  
Safeer Hussain ◽  
Jian Liu ◽  
Lei Wang ◽  
Bengt Sundén
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Vortex Generator ◽  
Diameter Ratio ◽  
Upstream Region ◽  
Spanwise Direction ◽  
Transfer Enhancement ◽  
Nusselt Numbers

Measurement of endwall heat transfer around a circular cylinder with a vortex generator pair has been investigated. Steady state liquid crystal thermography is adopted. Cylinders having two different height to diameter ratios have been employed. In one case, the cylinder has one end free in the flow and in the other case it has both ends attached on the walls. Local Nusselt numbers both upstream and downstream of the cylinder with and without the vortex generator pair are calculated. Nusselt numbers in streamwise and spanwise directions for both cases with vortex generator are compared with each other as well as with corresponding base cases. It is found from the experiments that the vortex generator influences the endwall heat transfer significantly downstream of the cylinder but has a small effect in the upstream region. Moreover, for different height to diameter ratio of the cylinder different heat transfer patterns are observed downstream of the cylinder. The vortex generator pair plays its major role on the endwall heat transfer enhancement in the spanwise direction and it expands as one moves from the upstream to downstream direction. To fully understand the advantage of the vortex generator pair, thermal performance is calculated for each case and it was found that in presence of the vortex generator pair, the cylinder with shorter height to diameter ratio shows higher thermal performance. Reynolds number dependence has also been investigated and it was found that the thermal performance decreases with increasing Reynolds number for both cases having a vortex generator pair.

Visualization of Flow Phenomena Near Enhanced Surfaces

1994 ◽  
Vol 116 (1) ◽  
pp. 54-57 ◽  
Author(s):  
T. S. Ravigururajan ◽  
A. E. Bergles
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchangers ◽  
Working Fluid ◽  
Hydraulic Characteristics ◽  
Transfer Enhancement ◽  
Flow Phenomena ◽  
Augmentation Techniques ◽  
Simultaneous Existence ◽  
Physical Phenomena

Passive augmentation techniques such as surface disruptions are being increasingly used in heat exchangers. Although many working correlations have been suggested to predict their thermal-hydraulic characteristics, the physical phenomena governing the heat transfer enhancement have not been clearly understood. The paper describes a qualitative study on the flow phenomena near an enchanced surface. Water was used as the working fluid. Experiments were conducted for different coil wire diameters and for a Reynolds number of 150-2600. The results show the simultaneous existence of different flow patterns in enhanced flow. Also, the study confirmed that the developing length is very much smaller than that of a smooth tube, even for laminar flow.

scholarly journals Experimental Investigation of Heat Transfer Rate Using Twisted Tape with Elliptical Holes

2017 ◽  
Vol 7 (2 (S)) ◽  
pp. 105
Author(s):  
K. R. Gawande ◽  
A. V. Deshmukh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Experimental Investigation ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Test Section ◽  
Smooth Tube ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Nusselt Numbers

An experimental investigation was carried for measuring tube-side heat transfer coefficient, friction factor, heat transfer enhancement efficiency of water for turbulent flow in a circular tube fitted with rectangular-cut twisted tape insert. A copper tube of 26.6 mm internal diameter and 30 mm outer diameter and 900 mm test length was used. A stainless steel rectangular-cut twisted tape insert of 5.25 twist ratio was inserted into the smooth tube. The rectangular cut had 8 mm depth and 14 mm width. A uniform heat flux condition was created by wrapping nichrome wire around the test section and fiber glass over the wire. Outer surface temperatures of the tube were measured at 5 different points of the test section by T-type thermocouples. Two thermometers were used for measuring the bulk temperatures. At the outlet section the thermometer was placed in a mixing box. The Reynolds numbers were varied in the range 10000-19000 with heat flux variation 14 to 22 kW/m2 for smooth tube, and 23 to 40 kW/m2 for tube with insert. Nusselt numbers obtained from smooth tube were compared with Gnielinski correlation and errors were found to be in the range of -6% to -25% with r.m.s. value of 20%. At comparable Reynolds number, Nusselt numbers in tube with rectangular-cut twisted tape insert were enhanced by 2.3 to 2.9 times at the cost of increase of friction factors by 1.4 to 1.8 times compared to that of smooth tube. Heat transfer enhancement efficiencies were found to be in the range of 1.9 to 2.3 and increased with the increase of Reynolds number.

scholarly journals What dominates heat transfer performance of a double-pipe heat exchanger

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 863-866
Author(s):  
Dan Zheng ◽  
Zhenwei Hu ◽  
Liting Tian ◽  
Jin Wang ◽  
Bengt Sundén
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Enhancement ◽  
Nusselt Numbers ◽  
Corrugated Tube ◽  
Helical Corrugation ◽  
Double Pipe ◽  
Pipe Heat

Abstract ZnO–water nanofluid in an inner pipe was experimentally investigated to improve the thermal efficiency of double-pipe heat exchangers. In this work, a 57.6% increase in the Nusselt number was obtained at Re = 14,340 when the ZnO–water nanofluid flowed through a helically corrugated tube. It was found that helical corrugation played a more important role in heat transfer enhancement than thermophysical properties of the nanofluid at the Reynolds number below 10,221. In addition, with the increase of the Reynolds number, the advantages of nanofluids in thermal performance become obvious, and Nusselt numbers increase by 28.5 and 30.6% with the effects of helical corrugation and ZnO–nanofluid, respectively, at Re = 14,349.

Heat transfer enhancement from inline and staggered arrays of cylinders in a heat exchanger using alumina-water nanofluid

2020 ◽  
pp. 1-31
Author(s):  
Mohd. Asif ◽  
Rashi Chaturvedi ◽  
Amit Dhiman
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Nanoparticle Concentration ◽  
Transfer Enhancement ◽  
Particle Volume ◽  
Circular Tubes ◽  
Heat Transfer Augmentation

Abstract The flow of alumina-water nanofluid across heated circular tubes arranged in inline and staggered arrays in a heat exchanger has been studied. The thermophysical properties of the nanofluid are determined using Corcione correlations, which are based on several experiments. The nanoparticle diameter dp is between 10 and 50 nm, with particle volume fraction ϕ varying from 0.01 to 0.05 and Reynolds number Re ranging from 10 to 200. Heat transfer augmentation takes place when nanoparticle concentration is increased. Mean Nusselt number NuM is increased by 31% when ϕ is increased from 0.01 to 0.05 at Re = 200 and dp = 10 nm in an inline array and by 25% in a staggered array. The use of smaller nanoparticles significantly promotes the thermal performance of the heat exchange arrays; NuM is enhanced by 20% for the inline array and by 16% for the staggering array when dp decreases from 50 nm to 10 nm at Re = 200 and ϕ = 0.05. NuM of the staggering array of cylinders at Re = 200, dp = 10 nm and ϕ = 0.05 is 60% greater than NuM of an inline array of cylinders. Finally, correlations are derived for the calculation of NuM of inline as well as staggered arrays.

scholarly journals Effect of Integrating Metal Wire Mesh with Spray Injection for Liquid Piston Gas Compression

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3723
Author(s):  
Barah Ahn ◽  
Vikram C. Patil ◽  
Paul I. Ro
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Metal Wire ◽  
Wire Mesh ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Gas Compression ◽  
Liquid Piston

Heat transfer enhancement techniques used in liquid piston gas compression can contribute to improving the efficiency of compressed air energy storage systems by achieving a near-isothermal compression process. This work examines the effectiveness of a simultaneous use of two proven heat transfer enhancement techniques, metal wire mesh inserts and spray injection methods, in liquid piston gas compression. By varying the dimension of the inserts and the pressure of the spray, a comparative study was performed to explore the plausibility of additional improvement. The addition of an insert can help abating the temperature rise when the insert does not take much space or when the spray flowrate is low. At higher pressure, however, the addition of spacious inserts can lead to less efficient temperature abatement. This is because inserts can distract the free-fall of droplets and hinder their speed. In order to analytically account for the compromised cooling effects of droplets, Reynolds number, Nusselt number, and heat transfer coefficients of droplets are estimated under the test conditions. Reynolds number of a free-falling droplet can be more than 1000 times that of a stationary droplet, which results in 3.95 to 4.22 times differences in heat transfer coefficients.

Effects of Insulated and Isothermal Baffles on Pseudosteady-State Natural Convection Inside Spherical Containers

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Yuping Duan ◽  
S. F. Hosseinizadeh ◽  
J. M. Khodadadi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Numerical Procedure ◽  
Boussinesq Approximation ◽  
Transfer Enhancement ◽  
Nusselt Numbers ◽  
Extended Surface ◽  
Parametric Studies ◽  
Thermal Layer

The effects of insulated and isothermal thin baffles on pseudosteady-state natural convection within spherical containers were studied computationally. The computations are based on an iterative, finite-volume numerical procedure using primitive dependent variables. Natural convection effect is modeled via the Boussinesq approximation. Parametric studies were performed for a Prandtl number of 0.7. For Rayleigh numbers of 104, 105, 106, and 107, baffles with three lengths positioned at five different locations were investigated (120 cases). The fluid that is heated adjacent to the sphere rises replacing the colder fluid, which sinks downward through the stratified stable thermal layer. For high Ra number cases, the hot fluid at the bottom of the sphere is also observed to rise along the symmetry axis and encounter the sinking colder fluid, thus causing oscillations in the temperature and flow fields. Due to flow obstruction (blockage or confinement) effect of baffles and also because of the extra heating afforded by the isothermal baffle, multi-cell recirculating vortices are observed. This additional heat is directly linked to creation of another recirculating vortex next to the baffle. In effect, hot fluid is directed into the center of the sphere disrupting thermal stratified layers. For the majority of the baffles investigated, the Nusselt numbers were generally lower than the reference cases with no baffle. The extent of heat transfer modification depends on Ra, length, and location of the extended surface. With an insulated baffle, the lowest amount of absorbed heat corresponds to a baffle positioned horizontally. Placing a baffle near the top of the sphere for high Ra number cases can lead to heat transfer enhancement that is linked to disturbance of the thermal boundary layer. With isothermal baffles, heat transfer enhancement is achieved for a baffle placed near the bottom of the sphere due to interaction of the counterclockwise rotating vortex and the stratified layer. For some high Ra cases, strong fluctuations of the flow and thermal fields indicating departure from the pseudosteady-state were observed.

Heat Transfer Enhancement in a Rectangular (AR = 3:1) Channel With V-Shaped Dimples

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
C. Neil Jordan ◽  
Lesley M. Wright
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Liquid Crystal ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Secondary Flows ◽  
Transfer Enhancement ◽  
Reduced Pressure

An alternative to ribs for internal heat transfer enhancement of gas turbine airfoils is dimpled depressions. Relative to ribs, dimples incur a reduced pressure drop, which can increase the overall thermal performance of the channel. This experimental investigation measures detailed Nusselt number ratio distributions obtained from an array of V-shaped dimples (δ/D = 0.30). Although the V-shaped dimple array is derived from a traditional hemispherical dimple array, the V-shaped dimples are arranged in an in-line pattern. The resulting spacing of the V-shaped dimples is 3.2D in both the streamwise and spanwise directions. A single wide wall of a rectangular channel (AR = 3:1) is lined with V-shaped dimples. The channel Reynolds number ranges from 10,000–40,000. Detailed Nusselt number ratios are obtained using both a transient liquid crystal technique and a newly developed transient temperature sensitive paint (TSP) technique. Therefore, the TSP technique is not only validated against a baseline geometry (smooth channel), but it is also validated against a more established technique. Measurements indicate that the proposed V-shaped dimple design is a promising alternative to traditional ribs or hemispherical dimples. At lower Reynolds numbers, the V-shaped dimples display heat transfer and friction behavior similar to traditional dimples. However, as the Reynolds number increases to 30,000 and 40,000, secondary flows developed in the V-shaped concavities further enhance the heat transfer from the dimpled surface (similar to angled and V-shaped rib induced secondary flows). This additional enhancement is obtained with only a marginal increase in the pressure drop. Therefore, as the Reynolds number within the channel increases, the thermal performance also increases. While this trend has been confirmed with both the transient TSP and liquid crystal techniques, TSP is shown to have limited capabilities when acquiring highly resolved detailed heat transfer coefficient distributions.

Local Heat Transfer Distribution in a Rotating Serpentine Rib-Roughened Flow Passage

1993 ◽  
Vol 115 (3) ◽  
pp. 560-567 ◽  
Author(s):  
N. Zhang ◽  
J. Chiou ◽  
S. Fann ◽  
W.-J. Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Performance ◽  
Height Ratio ◽  
Nusselt Numbers ◽  
Rayleigh Numbers ◽  
Rib Roughened

Experiments are performed to determine the local heat transfer performance in a rotating serpentine passage with rib-roughened surfaces. The ribs are placed on the trailing and leading walls in a corresponding posited arrangement with an angle of attack of 90 deg. The rib height-to-hydraulic diameter ratio, e/Dh, is 0.0787 and the rib pitch-to-height ratio, s/e, is 11. The throughflow Reynolds number is varied, typically at 23,000, 47,000, and 70,000 in the passage both at rest and in rotation. In the rotation cases, the rotation number is varied from 0.023 to 0.0594. Results for the rib-roughened serpentine passages are compared with those of smooth ones in the literature. Comparison is also made on results for the rib-roughened passages between the stationary and rotating cases. It is disclosed that a significant enhancement is achieved in the heat transfer in both the stationary and rotating cases resulting from an installation of the ribs. Both the rotation and Rayleigh numbers play important roles in the heat transfer performance on both the trailing and leading walls. Although the Reynolds number strongly influences the Nusselt numbers in the rib-roughened passage of both the stationary and rotating cases, Nuo and Nu, respectively, it has little effect on their ratio Nu/Nuo.

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