Heat Transfer Enhancement Using Laminar Gas-Liquid Segmented Fluid Streams

2009 ◽  
Author(s):  
Y. S. Muzychka ◽  
E. J. Walsh ◽  
P. Walsh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Liquid Fraction ◽  
Phase Flow ◽  
Fluid Circulation ◽  
Transfer Enhancement ◽  
Enhanced Heat Transfer ◽  
Two Phase ◽  
Internal Fluid ◽  
Existing Data

Heat transfer enhancement using segmented non-boiling gas-liquid streams is examined. Segmentation results in a two phase flow of liquid/gas having a constant liquid fraction, i.e. no phase change occurs. In this flow configuration, enhanced heat transfer occurs as a result of a shorter effective thermal length and internal fluid circulation in the liquid plugs. A simple theory for laminar segmented flows is developed based on Graetz theory and comparisons made with existing data from the literature and new data obtained in a companion study.

Heat Transfer Enhancement Using Laminar Gas-Liquid Segmented Plug Flows

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Y. S. Muzychka ◽  
E. J. Walsh ◽  
P. Walsh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Liquid Fraction ◽  
Tube Length ◽  
Published Data ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Internal Fluid ◽  
Proposed Model ◽  
Gas Liquid Flow

Heat transfer enhancement using segmented nonboiling gas-liquid flow is examined. Segmentation results in a two phase flow of liquid/gas having a constant liquid fraction; i.e., no phase change occurs. In this flow configuration, enhanced heat transfer occurs as a result of a shorter effective thermal length due to internal fluid circulation in the liquid plugs. A simple theory for laminar segmented flows is developed based on scaled Graetz theory and comparisons made with existing published data from the literature and new experimental data obtained in a companion study. The proposed model is valid for an isothermal tube wall provided that the axial residence time of the flow is such that dimensionless tube length L⋆<0.1.

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

scholarly journals Convective Heat Transfer of Ethanol/Polyalphaolefin Nanoemulsion in Mini- and Microchannel Heat Exchangers for High Heat Flux Electronics Cooling

2021 ◽  
Author(s):  
Jaime Rios ◽  
Mehdi Kabirnajafi ◽  
Takele Gameda ◽  
Raid Mohammed ◽  
Jiajun Xu
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Phase Flow ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Flow And Heat Transfer

The present study experimentally and numerically investigates the flow and heat transfer characteristics of a novel nanostructured heat transfer fluid, namely, ethanol/polyalphaolefin nanoemulsion, inside a conventionally manufactured minichannel of circular cross section and a microchannel heat exchanger of rectangular cross section manufactured additively using the Direct Metal Laser Sintering (DMLS) process. The experiments were conducted for single-phase flow of pure polyalphaolefin (PAO) and ethanol/PAO nanoemulsion fluids with two ethanol concentrations of 4 wt% and 8 wt% as well as for two-phase flow boiling of nanoemulsion fluids to study the effect of ethanol nanodroplets on the convective flow and heat transfer characteristics. Furthermore, the effects of flow regime of the working fluids on the heat transfer performance for both the minichannel and microchannel heat exchangers were examined within the laminar and transitional flow regimes. It was found that the ethanol/PAO nanoemulsion fluids can improve convective heat transfer compared to that of the pure PAO base fluid under both single- and two-phase flow regimes. While the concentration of nanoemulsion fluids did not reflect a remarkable distinction in single-phase heat transfer performance within the laminar regime, a significant heat transfer enhancement was observed using the nanoemulsion fluids upon entering the transitional flow regime. The heat transfer enhancement at higher concentrations of nanoemulsion within the transitional regime is mainly attributed to the enhanced interaction and interfacial thermal transport between ethanol nanodroplets and PAO base fluid. For two-phase flow boiling, heat transfer coefficients of ethanol/PAO nanoemulsion fluids were further enhanced when the ethanol nanodroplets underwent phase change. A comparative study on the flow and heat transfer characteristics was also implemented between the traditionally fabricated minichannel and additively manufactured microchannel of similar dimensions using the same working fluid of pure PAO and the same operating conditions. The results revealed that although the DMLS fabricated microchannel posed a higher pressure loss, a substantial heat transfer enhancement was achieved as compared to the minichannel heat exchanger tested under the same conditions. The non-post processed surface of the DMLS manufactured microchannel is likely to be the main contributor to the augmented heat transfer performance. Further studies are required to fully appreciate the possible mechanisms behind this phenomenon as well as the convective heat transfer properties of nanoemulsion fluids.

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

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 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

Heat transfer enhancement of droplet two-phase flow in cylindrical microchannel

2021 ◽  
Vol 186 ◽  
pp. 116474
Author(s):  
Xinlong Li ◽  
Liqun He ◽  
Peng Qian ◽  
Zizhen Huang ◽  
Chengyuan Luo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Cylindrical Microchannel
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