Experimental Investigation of Condensation Heat Transfer and Adiabatic Pressure Drop Characteristics Inside a Microfin and Smooth Tube

2017 ◽  
Vol 25 (03) ◽  
pp. 1750027 ◽  
Author(s):  
M. Mostaqur Rahman ◽  
Keishi Kariya ◽  
Akio Miyara
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Vapor Quality ◽  
Transfer Coefficients ◽  
Frictional Pressure Drop

Experiments on condensation heat transfer and adiabatic pressure drop characteristics of R134a were performed inside smooth and microfin horizontal tubes. The tests were conducted in the mass flux range of 50[Formula: see text]kg/m2s to 200[Formula: see text]kg/m2s, vapor quality range of 0 to 1 and saturation temperature range of 20[Formula: see text]C to 35[Formula: see text]C. The effects of mass velocity, vapor quality, saturation temperature, and microfin on the condensation heat transfer and frictional pressure drop were analyzed. It was discovered that the local heat transfer coefficients and frictional pressure drop increases with increasing mass flux and vapor quality and decreasing with increasing saturation temperature. Higher heat transfer coefficient and frictional pressure drop in microfin tube were observed. The present experimental data were compared with the existing well-known condensation heat transfer and frictional pressure drop models available in the open literature. The condensation heat transfer coefficient and frictional pressure drop of R134a in horizontal microfin tube was predicted within an acceptable range by the existing correlation.

Comparison of Evaporation and Condensation Characteristics Among Three Enhanced Tubes

2018 ◽  
Author(s):  
Kunrong Shen ◽  
Zhichuan Sun ◽  
Xiaolong Yan ◽  
Wei Li ◽  
David J. Kukulka ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Heat Transfer Performance ◽  
Saturation Temperature ◽  
Transfer Performance ◽  
Vapor Quality ◽  
Enhanced Tubes

With the current ozone depletion and global warming issues, it is critical to develop systems with better heat transfer performance and nontoxic refrigerants. An experimental investigation was performed to evaluate convective condensation and evaporation heat transfer characteristics using R410A at low mass fluxes. Experiments were conducted in a 12.0-mm O.D. horizontal smooth tube, and three enhanced tubes: 2EHT1 tube, 2EHT2 tube and 1EHT1 tube (O.D. 12.7 mm), with different sizes and shapes of dimple/protrusion and petal arrays. Refrigerant inlet quality varied in this study. Single phase experiment was conducted before the two-phase flow measurement. In-tube evaporation measurements of R410A were reported for saturation temperature at 6°C with vapor quality in the range of 0.2 to 0.9, and mass flux varied from 60 to 200 kg/m2s. Condensation tests were performed at saturation temperature of 45°C, vapor quality of 0.9 to 0.2, and mass flux of 60 to 260 kg/m2s. For evaporation with mass flux less than 200 kg/m2s, heat transfer coefficient of the 2EHT2 tube, 2EHT1 tube and 1EHT1 tube were greater than the experimental HTC (heat transfer coefficient) of smooth tube results by an average factor of 1.71, 1.69 and 1.87, respectively. Pressure drop in the 2EHT2 tube was 5% higher than the 2EHT1 tube and 1EHT1 tube. For condensation, when mass flux was less than 200 kg/m2s, the 1EHT1 tube showed obvious enhancement in heat transfer coefficient, while the pressure drop in the 1EHT1 tube was slightly 3–5% higher than that of the 2EHT1 tube and the 2EHT2 tube. In conclusion, for mass flux below 200 kg/m2s, the 1EHT1 tube presented the best heat transfer performance among others with R410A as the refrigerant.

Numerical Simulation of Forced Convective Condensation of Propane in a Spiral Tube

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
G. D. Qiu ◽  
W. H. Cai ◽  
Z. Y. Wu ◽  
Y. Yao ◽  
Y. Q. Jiang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Vapor Quality ◽  
Spiral Tube ◽  
Frictional Pressure Drop ◽  
Convective Condensation

A numerical simulation of forced convective condensation of propane in an upright spiral tube is presented. In the numerical simulations, the important models are used: implicit volume of fluid (VOF) multiphase model, Reynolds stress (RS) turbulence model, Lee's phase change model and Ishii's concentration model, and also the gravity and surface tension are taken into account. The mass flux and vapor quality are simulated from 150 to 350 kg·m−2·s−1 and from 0.1 to 0.9, respectively. The numerical results show that in all simulation cases, only the stratified flow, annular flow, and mist flow are observed. The heat transfer coefficient and frictional pressure drop increase with the increase of mass flux and vapor quality for all simulation cases. Under different flow patterns and mass flux, the numerical results of void fraction, heat transfer coefficient, and frictional pressure drop show good agreement with the experimental results and correlations from the existing references.

Shell-Side Condensation Characteristics of R410A on Horizontal Enhanced Tubes

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Weiyu Tang ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Diffusion Resistance ◽  
Outer Diameter ◽  
Vapor Quality ◽  
Enhanced Tubes ◽  
The Heat Transfer Coefficient

Abstract An experimental investigation into heat transfer characteristics during condensation on two horizontal enhanced tubes (EHTs) was conducted. All the tested EHTs s have similar geometries with an outer diameter of 12.7 mm, and a plain tube was also tested for comparison. Investigated enhanced surfaces consist of dimples, protrusions, and grooves, which may produce more flow turbulence and enhanced the liquid drainage effect. The effects of mass fluxes and vapor quality were compared and analyzed. Test conditions were as follows: saturation temperature fixed at 45 °C, mass flux varying from 100 to 200 kg m−2 s−1, and vapor quality ranging from 0.3 to 0.8. The heat transfer coefficient was presented, and the results show that the proposed enhanced surfaces seem to have worse performance than the conventional tubes when the mass flux is less than 150 kg m−2 s−1, while one of the enhanced tubes (2EHT-1) produce an enhanced ratio of 1.03–1.14 when G = 200 kg m−2 s−1. Besides, it was found that the heat transfer coefficient increases with increasing vapor quality, which can be attributed to the increasing diffusion resistance. Mass flux seems to have little effect on the heat transfer performance of smooth tubes, while that of 1EHT increases obviously with increasing mass flux, especially for high vapor qualities.

Experimental Apparatus for Measuring in Tube Condensation Heat Transfer Coefficient and Pressure Drop Using Smooth and Micro-Fin Tubes for HFC Refrigerants

2008 ◽  
Author(s):  
Pradeep A. Patil ◽  
S. N. Sapali
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Condensation Heat Transfer ◽  
Test Facility ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Fin Tube ◽  
Condensation Heat Transfer Coefficient

An experimental test facility is designed and built to calculate condensation heat transfer coefficients and pressure drops for HFC-134a, R-404A, R-407C, R-507A in a smooth and micro-fin tube. The main objective of the experimentation is to investigate the enhancement in condensation heat transfer coefficient and increase in pressure drop using micro-fin tube for different condensing temperatures and further to develop an empirical correlation for heat transfer coefficient and pressure drop, which takes into account the micro-fin tube geometry, variation of condensing temperature and temperature difference (difference between condensing temperature and average temperature of cooling medium). The experimental setup has a facility to vary the different operating parameters such as condensing temperature, cooling water temperature, flow rate of refrigerant and cooling water etc and study their effect on heat transfer coefficients and pressure drops. The hermetically sealed reciprocating compressor is used in the system, thus the effect of lubricating oil on the heat transfer coefficient is taken in to account. This paper reports the detailed description of design and development of the test apparatus, control devices, instrumentation, and the experimental procedure. It also covers the comparative study of experimental apparatus with the existing one from the available literature survey. The condensation and pressure drop of HFC-134a in a smooth tube are measured and obtained the values of condensation heat transfer coefficients for different mass flux and condensing temperatures using modified Wilson plot technique with correlation coefficient above 0.9. The condensation heat transfer coefficient and pressure drop increases with increasing mass flux and decreases with increasing condensing temperature. The results are compared with existing available correlations for validation of test facility. The experimental data points have good association with available correlations except Cavallini-Zecchin Correlation.

Experiment study on condensation heat transfer and pressure drop of steam flow inside rectangular tube with different aspect ratio

2020 ◽  
pp. 095765092097222
Author(s):  
Yan Yan ◽  
Jixian Dong ◽  
Tong Ren ◽  
Shiyu Feng
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Condensation Heat Transfer ◽  
Aspect Ratios ◽  
Rectangular Tubes ◽  
Condensation Heat Transfer Coefficient

In this study, the condensation heat transfer coefficient and pressure drop of steam are obtained in small rectangular tubes with different aspect ratios. The experiments were carried out on three rectangular tubes with aspect ratios of 1:2, 1:3 and 1:5, with mass flux between 25 and 45 kg/m2s, and vapor qualities between 0.1 and 0.8. The experimental data were analyzed to determine the effect of vapor quality, mass flux, and aspect ratio on the heat transfer coefficient and pressure drop. The results showed that the effect of aspect ratio on condensation heat transfer coefficient appears to be dependent on the flow pattern. For stratified flow, the condensation heat transfer coefficient increases as the mass flux increases. For annular flow, the condensation heat transfer coefficient hardly changed. The pressure drop always increases as the aspect ratio increases. Previous studies on round tube heat transfer and pressure drop correlations have not successfully predicted the small rectangular tube data; therefore, modified Shah correlation and Lockhart & Martinelli correlation are proposed, which predict the data with 20% and 23% RMS error, respectively.

An Experimental Investigation of Condensation Heat Transfer Coefficients and Pressure Drops of Refrigerants Inside Multiport Mini-channel Tubes

2017 ◽  
Vol 25 (02) ◽  
pp. 1750013 ◽  
Author(s):  
Pham-Quang Vu ◽  
Kwang-Il Choi ◽  
Jong-Taek Oh ◽  
Honggi Cho
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Condensation Heat Transfer ◽  
Working Fluid ◽  
Vapor Quality ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients

The condensation heat transfer coefficients and pressure drops of R410A and R22 flowing inside a horizontal aluminum multiport mini-channel tube having 18 channels are investigated. Experimental data are presented for the range of vapor quality from 0.1 to 0.9, mass flux from 50 to 500[Formula: see text]kg/m2s, heat flux from 3 to 15[Formula: see text]kW/m2 and the saturation temperature at 48[Formula: see text]C. The pressure drop across the test section was directly measured by a differential pressure transducer. At a small scale, the noncircular cross-sections can enhance the effect of the surface tension. The average heat transfer coefficient increased with the increase of vapor quality, mass flux and heat flux. Under the same test conditions, the heat transfer coefficients of R22 are higher than those for R410A, the pressure drops for R410A are 7–19% lower than those of R22. The lower pressure drop of R410A has an important advantage as an alternative working fluid for R22 in air-conditioning and heat pump systems.

Effects of Pitch and Depth on the Condensation Heat Transfer of R-134a Flowing Through Corrugated Tubes

2011 ◽  
Author(s):  
Suriyan Laohalertdecha ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
Maximum Heat ◽  
Frictional Pressure Drop ◽  
R 134A

The effects of pitch and depth on the condensation heat transfer of R-134a flowing inside corrugated tubes are experimentally investigated. The test section is a horizontal tube-in-tube heat exchanger. The refrigerant flows in the inner tube and the water flows in the annulus. The length of heat exchanger is 2 m. A smooth tube and corrugated tubes having inner diameters of 8.7 mm are used as an inner tube. The corrugation pitches used in this study are 5.08, 6.35, and 8.46 mm. Similarly, the corrugation depths are 1, 1.25, and 1.5 mm. The effects of corrugation pitch and depth on tube wall temperature, heat transfer coefficient and frictional pressure drop are discussed. The results illustrate that the maximum heat transfer coefficient and frictional pressure drop obtained from the corrugated tube are up to 50% and 70% higher than those obtained from the smooth tube, respectively.

Experimental Investigation of Evaporation and Condensation in Herringbone, Smooth and EHT Tubes

2015 ◽  
Author(s):  
Xiao-peng Zhou ◽  
Jian-jun Sun ◽  
Si-pu Guo ◽  
Sun Zhichuan ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
Evaporation And Condensation ◽  
Condensation Heat Transfer Coefficient

An experimental investigation was performed for evaporation and condensation characteristics inside smooth tube, herringbone tube and EHT tube with the same outer diameter 12.7 mm, refrigerant are R22 and R410a. Mass flux are 60–140 kg/m2s, 81–178.5 kg/m2s, for evaporation and condensation respectively. The evaporation saturation temperature is 6°C, with inlet and outlet vapor qualities of 0.1 and 0.9, respectively. The condensation saturation temperature is 47°C, with inlet and outlet vapor qualities of 0.8 and 0.2, respectively. EHT tube has best evaporating performance for both R22 and R410a. Herringbone tube is also batter than smooth tube. Evaporation heat transfer coefficient increases with mass flux increasing obviously. Pressure drop of R22 evaporation in EHT tube is the highest, herringbone tube is a little higher than in smooth tube. Herringbone tube has highest condensation heat transfer coefficient, about 3 and 2.3 times that of smooth tube for R22 and R410a respectively. EHT tube has heat transfer coefficient about 2 and 1.8 times that of smooth tube for R22 and R410a respectively. Condensation heat transfer coefficient increases with increasing of mass flux, but very slowly, R410a flow in micro-fin tube even decreases with mass flux increasing.

Hydrocarbon Refrigerant Vaporization Inside a Brazed Plate Heat Exchanger

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Giovanni A. Longo
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Transfer Coefficients ◽  
Frictional Pressure Drop ◽  
Heat Transfer Coefficients ◽  
Experimental Heat ◽  
Fluid Properties

This paper presents the experimental heat transfer coefficients and pressure drop measured during HC-600a (isobutane), HC-290 (propane), and HC-1270 (propylene) vaporization inside a brazed plate heat exchanger (BPHE): the effects of heat flux, refrigerant mass flux, saturation temperature (pressure), evaporator outlet condition, and fluid properties are investigated. The experimental tests include 172 vaporization runs carried out at three different saturation temperatures (10, 15, and 20 °C) and four different evaporator outlet conditions (outlet vapor quality around 0.80 and 1.00, outlet vapor super-heating around 5 and 10 °C). The refrigerant mass flux ranges from 6.6 to 23.9 kg m−2 s−1 and the heat flux from 4.3 to 19.6 kW m−2. The heat transfer and pressure drop measurements have been complemented with IR thermography analysis in order to quantify the portion of the heat transfer surface affected by vapor super-heating. The heat transfer coefficients show great sensitivity to heat flux, evaporator outlet condition and fluid properties and weak sensitivity to saturation temperature (pressure). The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on refrigerant mass flux. HC-1270 exhibits heat transfer coefficients 6–12% higher than HC-290 and 35–50% higher than HC-600a and frictional pressure drops 5–10% lower than HC-290 and 60% lower than HC-600a. The experimental heat transfer coefficients are compared with two well-known correlations for nucleate boiling and a linear equation for frictional pressure drop is proposed.

scholarly journals Correlation for Condensation Heat Transfer in a 4.0 mm Smooth Tube and Relationship with R1234ze(E), R404A, and R290

2018 ◽  
Vol 8 (11) ◽  
pp. 2267 ◽  
Author(s):  
Norihiro Inoue ◽  
Masataka Hirose ◽  
Daisuke Jige ◽  
Junya Ichinose
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Small Diameter ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
General Correlation ◽  
Condensation Heat Transfer Coefficient

In this study, the condensation heat transfer coefficient and pressure drop characteristics of a 4 mm outside diameter smooth tube, using R32, R152a, R410A, and R1234ze(E) refrigerants, were examined. Condensation heat transfer coefficients and pressure drops were measured at a saturation temperature of 35 °C, in the region of mass velocities from 100 to 400 kg m−2s−1. The frictional pressure drop, and the condensation heat transfer from the new measurements, using R1234ze(E) as a refrigerant, were compared with those of R32, R152a, and R410A, in the smooth tube. Experimental values of condensation heat transfer coefficient of smooth tube were also compared to the predicted values obtained using the previously established correlations. The previous correlation from Cavallini et al., for the condensation heat transfer coefficient of small-diameter smooth tube, was estimated to be within ±30%. However, the general correlation, which can be easily predicted, for condensation heat transfer inside small-diameter smooth tubes, was suggested, and the relationship of the general correlation was compared with data for R1234ze(E) obtained by us, and R404A and R290 obtained by other researchers.

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