Heat transfer coefficients and pressure drops of highly viscous fluids in plate heat exchangers.

The plate and concentric tube heat exchangers are tested by using the water-water and nanofluid-water streams. The ZnO/Water (0.5%v/v) nanofluid has been used as the hot stream. The heat transfer rate omitted of hot stream and overall heat transfer coefficients in both heat exchangers are measured as a function of hot and cold streams mass flow rates. The experimental results show that the heat transfer rate and heat transfer coefficients of the nanofluid in both of the heat exchangers is higher than that of the base liquid (i.e., water) and the efficiency of plate heat exchange is higher than concentric tube heat exchanger. In the plate heat exchanger the heat transfer coefficient of nanofluid at mcold = mhot = 10 gr/sec is about 20% higher than base fluid and under the same conditions in the concentric heat exchanger is 14% higher than base fluid. The heat transfer rate and heat transfer coefficients increases with increase in mass flow rates of hot and cold streams. Also the CFD1 code is used to simulate the performance of the mentioned heat exchangers. The CFD results are compared to the experimental data and showed good agreement. It is shown that the CFD is a reliable tool for investigation of heat transfer of nanofluids in the various heat exchangers.

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Experimental heat transfer coefficients during refrigerant vaporisation and condensation inside herringbone-type plate heat exchangers with enhanced surfaces

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2004.05.001 ◽

2004 ◽

Vol 47 (19-20) ◽

pp. 4125-4136 ◽

Cited By ~ 52

Author(s):

G.A Longo ◽

A Gasparella ◽

R Sartori

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Transfer Coefficients ◽

Plate Heat ◽

Heat Transfer Coefficients ◽

Experimental Heat ◽

Experimental Heat Transfer

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A numerical study on condensation heat transfer and pressure drop characteristics of low-pressure vapor in a plate heat exchanger

Thermal Science ◽

10.2298/tsci190914095z ◽

2020 ◽

pp. 95-95

Author(s):

Zhongbin Zhang ◽

Tianyu Zhang ◽

Hao Zhang

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Mass Flow ◽

Numerical Study ◽

Flow Direction ◽

Condensation Heat Transfer ◽

Transfer Coefficients ◽

Pressure Drops ◽

Plate Heat ◽

Heat Transfer Coefficients

In this work, the condensation heat transfer and pressure drop characteristics of plate heat exchangers were simulated, and the threedimensional temperature, pressure, and velocity fields were obtained. From the flow field, we can see that the velocity of vapor is higher than that of condensate. From the pressure field, we can see that the pressure shows a downward trend along the flow direction, and there is, the more pressure drop in the first half of the plate. From the temperature field, we can see that the temperature gradient increases with the increase of velocity and pressure gradient. Meanwhile, the effect of vapor mass flow, dryness and superheat on condensation heat transfer coefficients and pressure drops were investigated. The results show that the pressure drop and heat transfer coefficient both increase with the increase of dryness, degree of superheat and mass flow. In addition, the correlation equations developed to predict the condensation heat transfer and friction factor perfectly agree with the experimental results.

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Experimental quantification of air-side row-by-row heat transfer coefficients on fin-and-tube heat exchangers

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2021.06.012 ◽

2021 ◽

Author(s):

Min Che ◽

Stefan Elbel

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Transfer Coefficients ◽

Heat Transfer Coefficients

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Heat Transfer Enhancement in Triangular Ducts With an Array of Side-Entry Wall/Impinged Jets

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/99-gt-195 ◽

1999 ◽

Author(s):

J.-J. Hwang ◽

C.-S. Cheng ◽

Y.-P. Tsia

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Leading Edge ◽

Local Heat Transfer ◽

Local Heat ◽

Transfer Enhancement ◽

Transfer Coefficients ◽

Pressure Drops ◽

Heat Transfer Coefficients ◽

Inclined Angle

An experimental study has been performed to measure local heat transfer coefficients and static well pressure drops in leading-edge triangular ducts cooled by wall/impinged jets. Coolant provided by an array of equally spaced wall jets is aimed at the leading-edge apex and exits from the radial outlet. Detailed heat transfer coefficients are measured for the two walls forming the apex using transient liquid crystal technique. Secondary-flow structures are visualized to realize the mechanism of heat transfer enhancement by wall/impinged jets. Three right-triangular ducts of the same altitude and different apex angles of β = 30 deg (Duct A), 45 deg (Duct B) and 60 deg (Duct C) are tested for various jet Reynolds numbers (3000≦Rej≦12600) and jet spacings (s/d = 3.0 and 6.0). Results show that an increase in Rej increases the heat transfer on both walls. Local heat transfer on both walls gradually decreases downstream due to the crossflow effect. At the same Rej, the Duct C has the highest wall-averaged heat transfer because of the highest jet center velocity as well as the smallest jet inclined angle. Moreover, the distribution of static pressure drop based on the local through flow rate in the present triangular duct is similar to that that of developing straight pipe flows. Average jet Nusselt numbers on the both walls have been correlated with jet Reynolds number for three different duct shapes.

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Experimental Study of Evaporation Heat Transfer Characteristics and Pressure Drops of R410A and R134a in a Multiport Mini-Channel

ASME 2009 7th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2009-82209 ◽

2009 ◽

Cited By ~ 1

Author(s):

Jatuporn Kaew-On ◽

Somchai Wongwises

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Pressure Drop ◽

Transfer Coefficient ◽

Transfer Coefficients ◽

Pressure Drops ◽

Heat Transfer Coefficients ◽

Evaporation Heat ◽

Evaporation Heat Transfer ◽

R 134A

The evaporation heat transfer coefficients and pressure drops of R-410A and R-134a flowing through a horizontal-aluminium rectangular multiport mini-channel having a hydraulic diameter of 3.48 mm are experimentally investigated. The test runs are done at refrigerant mass fluxes ranging between 200 and 400 kg/m2s. The heat fluxes are between 5 and 14.25 kW/m2, and refrigerant saturation temperatures are between 10 and 30 °C. The effects of the refrigerant vapour quality, mass flux, saturation temperature and imposed heat flux on the measured heat transfer coefficient and pressure drop are investigated. The experimental data show that in the same conditions, the heat transfer coefficients of R-410A are about 20–50% higher than those of R-134a, whereas the pressure drops of R-410A are around 50–100% lower than those of R-134a. The new correlations for the evaporation heat transfer coefficient and pressure drop of R-410A and R-134a in a multiport mini-channel are proposed for practical applications.

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