Experimental investigation on thermal behavior of non-boiling slug and bubbly two phase-flow in helical tube with spiral

2021 ◽  
pp. 095440622110420
Author(s):  
Reza Rezazadeh ◽  
Samad Jafarmadar ◽  
Saleh Khorasani ◽  
Seyed Reza Amini Niaki
Keyword(s):  
Heat Transfer ◽  
Thermal Behavior ◽  
Two Phase Flow ◽  
Glass Tube ◽  
Constant Heat Flux ◽  
Phase Flow ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Helical Tube ◽  
The Heat Transfer Coefficient

The present study provides experimental results of the flow pattern and thermal behavior of a none-boiling air-water two-phase flow in a helical tube with a turbulator. In order to evaluate the thermal behavior, a glass tube was put under constant heat flux. The inlet, outlet, and surface temperature of the helical tube were measured to calculate the heat transfer coefficient. The results showed that the addition of the turbulator in the helical tube leads to a rapid conversion from bubble flow to slug flow. Also, the formed bubbles are much smaller and spread radially throughout the pipe. Findings showed that the turbulator significantly improved the heat transfer of the two-phase flow, in which ratios of heat transfer enhancement with and without turbulator is 28% and 19%, respectively. Finally, cost-to-benefit ratio (C.B.R) analysis confirmed that when air-water two-phase flow transits through the helical tube are not affected by the presence or absence of turbulator.

scholarly journals Two-Phase Flow and Heat Transfer Enhancement

2013 ◽  
Vol 5 ◽  
pp. 256839
Author(s):  
Somchai Wongwises ◽  
Afshin J. Ghajar ◽  
Kwok-wing Chau ◽  
Octavio García Valladares ◽  
Balaram Kundu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Flow And Heat Transfer

Boiling heat transfer enhancement of two phase flow in lunate channel

Cryogenics ◽  
1994 ◽  
Vol 34 ◽  
pp. 353-356 ◽  
Author(s):  
Wu Yuyuan ◽  
Lu Yu ◽  
Chen Liufang ◽  
Sun Changhai
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Boiling Heat Transfer ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Transfer Enhancement ◽  
Two Phase

Impact of Channel Geometry on Two-Phase Flow Heat Transfer Characteristics of Refrigerants in Microchannel Heat Exchangers

1998 ◽  
Vol 120 (2) ◽  
pp. 485-491 ◽  
Author(s):  
T. S. Ravigururajan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Heat ◽  
The Heat Transfer Coefficient

Microchannel surfaces, often machined to 20 to 1000 μm in width and depth, are employed in high-heat-flux applications. However, a large number of variables, control the two-phase flow heat transfer coefficient. The pressure, the surface heat flux, and the mass flux significantly affect the thermal transport. Experiments were conducted on a setup that was built for testing microchannel heat exchanges. The parameters considered in the study are power input: 20 to 300 W, volume flow rate: 35 to 300 ml/min, quality: 0 to 0.5, inlet subcooling: 5 to 15°C. The results indicate that the heat transfer coefficient and pressure drop are functions of the flow quality, the mass flux, and, of course, the heat flux and the related surface superheat. The heat transfer coefficient decreases from a value of 12,000 W/m2-K to 9000, W/m2-K at 80°C, when the wall superheat is increased from 10 to 80°C. The coefficient decreases by 30 percent when the exit vapor quality is increased from 0.01 to 0.65.

Two-Phase Flow Patterns During Microchannel Vaporization of CO2 at Near-Critical Pressures

2003 ◽  
Author(s):  
Jostein Pettersen
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Bubble Formation ◽  
Glass Tube ◽  
Flow Patterns ◽  
High Mass ◽  
Phase Flow ◽  
Two Phase

Carbon dioxide (CO2 / R-744) is receiving renewed interest as a refrigerant, in many cases based on systems with microchannel heat exchangers that have high pressure capability, efficient heat transfer, and compact design. A good understanding of two-phase flow of evaporating CO2 in microchannels is needed to analyze and predict heat transfer. A special test rig was built in order to observe two-phase flow patterns, using a horizontal quartz glass tube with ID 0.98 mm, externally coated by a transparent resistive film. Heat flux was obtained by applying DC power to the film, and flow patterns were recorded at 4000 or 8000 frames per second by a digital video camera. Flow patterns were recorded for temperatures 20°C and 0°C, and for mass flux ranging from 100 to 580 kgm−2s−1. The observations showed a dominance of intermittent (slug) flow at low x, and wavy annular flow with entrainment of droplets at higher x. At high mass flux, the annular/entrained flow pattern could be described as dispersed. The aggravated dryout problem reported from heat transfer experiments at high mass flux could be explained by increased entrainment. Stratified flow was not observed in the tests with heat load. Bubble formation and growth could be observed in the liquid film, and the presence of bubbles gave differences in flow pattern compared to adiabatic flow. The flow pattern observations did not fit generalized maps or transition lines showed in the literature.

Numerical investigation of EHD effects on heat transfer enhancement and flow pattern of R-134a two phase flow

2016 ◽  
Vol 82 ◽  
pp. 63-71 ◽  
Author(s):  
Pedram Hanafizadeh ◽  
Mahla Gharahasanlo ◽  
Sadegh Ahmadi ◽  
Shahab Zeraati ◽  
M.A. Akhavan-Behabadi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Flow Pattern ◽  
Numerical Investigation ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Transfer Enhancement ◽  
Two Phase ◽  
R 134A

scholarly journals Evaluation of Heat Transfer Coefficient of Two-Phase Flow Boiling with R290 in Horizontal Mini Channel

2021 ◽  
Vol 88 (3) ◽  
pp. 88-95
Author(s):  
Ronald Akbar ◽  
Jong Taek Oh ◽  
Agus Sunjarianto Pamitran
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Phase Flow ◽  
Two Phase ◽  
The Heat Transfer Coefficient

Various experiments have been conducted on the heat transfer coefficient of two-phase flow boiling in mini channel tubes. In addition to obtaining data on the heat transfer coefficients through experiments, many researchers have also compared their experimental data using existing correlations. This research aims to determine the characteristics of the heat transfer coefficient of refrigerant R290 from the data used by processing and knowing the best heat transfer coefficient correlation in predicting the experimental data so that the results are expected to be a reference for designing a heat exchanger or for further research. The experimental data predicted is the two-phase flow boiling in a horizontal tube 3 mm diameter, with the mass flux of 50-180 kg/m2s, heat flux of 5-20 kW/m2, saturation temperature of 0-11 °C, and vapor quality of 0-1. The correlation used in this research is based on the asymptotic flow model, where the model is a combination of the nucleate and convective flow boiling mechanisms. The results show an effect of mass flux and heat flux on the experimental heat transfer coefficient and the predicted R290 heat transfer coefficient with asymptotic correlations had a good and similar result to the experimental data.

scholarly journals Heat Transfer Enhancement Using R1234yf Refrigerants in Micro-Ribbed Tubes in a Two-Phase Flow Regime

2020 ◽  
Vol 16 (6) ◽  
pp. 1259-1272
Author(s):  
Daoming Shen ◽  
Xia Zhang ◽  
Wei He ◽  
Jinhong Xia ◽  
Songtao Xue
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Flow Regime ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Transfer Enhancement ◽  
Two Phase

Experimental Study of Heat Transfer, Pressure Drop, and Dryout for Flow Boiling of Water in an Oil Heated Minichannel

2004 ◽  
Author(s):  
Levi A. Campbell ◽  
Satish Kandlikar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Test Section ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Small Diameter ◽  
Constant Heat Flux ◽  
Phase Flow ◽  
Two Phase ◽  
Mass Fluxes

Heat transfer and pressure drop, are experimentally recorded for flow boiling water in a single 706 μm circular copper channel 158.75 mm long. Heat is supplied by heat transfer oil at specified temperatures to a helical channel in the test section. In contrast to other current experimental techniques for flow boiling in small diameter tubes, a uniform temperature boundary condition is employed rather than a constant heat flux condition. The principal results of these experiments are two-phase flow boiling heat transfer rates and an analysis of the time-dependent pressure drop signature during two-phase flow in a minichannel. The range of experiments includes mass fluxes of 43.8–3070 kg/m2s and wall temperatures of 100°C–171.2°C. In all cases the test section water inlet is subcooled to between 72.9°C and 99.6°C. The inlet pressures used are 1.1–230.5 kPa (gage).

Sign in / Sign up

Export Citation Format

Share Document