Hydrodynamic and Thermal Performance of a Vapor-Venting Microchannel Copper Heat Exchanger

2008 ◽  
Author(s):  
Milnes P. David ◽  
Amy Marconnet ◽  
Kenneth E. Goodson
Keyword(s):  
Heat Exchanger ◽  
Carbon Fiber ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Single Phase ◽  
Two Phase ◽  
Microchannel Heat Exchanger ◽  
Large Pressure ◽  
Dry Out

Two-phase microfluidic cooling has the potential to achieve low thermal resistances with relatively small pumping power requirements compared to single-phase heat exchanger technology. Two-phase cooling systems face practical challenges however, due to the instabilities, large pressure drop, and dry-out potential associated with the vapor phase. Our past work demonstrated that a novel vapor-venting membrane attached to a silicon microchannel heat exchanger can reduce the pressure drop for two-phase convection. This work develops two different types of vapor-venting copper heat exchangers with integrated hydrophobic PTFE membranes and attached thermocouples to quantify the thermal resistance and pressure-drop improvement over a non-venting control. The first type of heat exchanger, consisting of a PTFE phase separation membrane and a 170 micron thick carbon-fiber support membrane, shows no improvement in the thermal resistance and pressure drop. The results suggest that condensation and leakage into the carbon-fiber membrane suppresses venting and results in poor device performance. The second type of heat exchanger, which evacuates any liquid water on the vapor side of the PTFE membrane using 200 ml/min of air, reduces the thermal resistance by almost 35% in the single-phase regime in comparison. This work shows that water management, mechanical and surface properties of the membrane as well as its attachment and support within the heat exchanger are all key elements of the design of vapor-venting heat exchangers.

Numerical Simulation of Manifold Microchannel Heat Exchanger

2016 ◽  
Author(s):  
Muhammad Ansab Ali ◽  
Tariq S. Khan ◽  
Ebrahim Al Hajri
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Water Mixture ◽  
Microchannel Heat Exchanger ◽  
Compact Size

The quest to achieve higher heat transfer rate, smaller size and minimum pressure drop is a main area of focus in the design of heat exchangers. Plate heat exchangers are one of viable candidates to deliver higher heat duties but still have a drawback of higher pressure drop due to long restricted flow path. Motivated by demand of miniaturization and cost reduction, a novel design of tubular microchannel heat exchanger for single phase flow employing ammonia water mixture is proposed. Numerical simulation of unit fluid domain is conducted in ANSYS Fluent. Parametric study of the different flow geometries is evaluated in terms of Nusselt number and pressure drop. The salient features of the design include ultra-compact size with higher heat transfer rate and acceptable pressure drop.

Development of a Microchannel Heat Exchanger for Aerospace Applications

2012 ◽  
Author(s):  
Hal Strumpf ◽  
Zia Mirza
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
State Of The Art ◽  
Design And Optimization ◽  
Microchannel Heat Exchanger ◽  
Aerospace Applications ◽  
Accurate Design ◽  
Adjustment Factors

Honeywell Aerospace has been developing microchannel heat exchangers for aerospace use. These heat exchangers offer significant reduction in volume and some reduction in weight compared to state-of-the-art aerospace heat exchangers constructed using offset plate and fin interupted surfaces. A microchannel heat exchanger was designed based on the requirements and available envelope for an aerospce liquid-to-air heat exchanger presently in service. The new micochannel heat exchanger was fabricated and a full testing campaign was undertaken to validate the design approach and generate appropriate adjustment factors for pressure drop and heat transfer. Based on this correlated model, the heat exchanger was re-sized for the required conditions. This updated design shows a significant reduction in size compared to the existing heat exchanger. In addition, Honeywell now has a validated approach enabling accurate design and optimization of microchannel heat exchangers for diverse problem conditions.

Single phase pressure drop and two-phase distribution in an offset strip fin compact heat exchanger

2012 ◽  
Vol 49 ◽  
pp. 99-105 ◽  
Author(s):  
Selma Ben Saad ◽  
Patrice Clément ◽  
Jean-François Fourmigué ◽  
Caroline Gentric ◽  
Jean-Pierre Leclerc
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Single Phase ◽  
Phase Distribution ◽  
Compact Heat Exchanger ◽  
Two Phase ◽  
Offset Strip Fin ◽  
Phase Pressure

A Relation Between Two-Phase Pressure Drop and Flow Distribution in a Compact Heat Exchanger Header

2004 ◽  
Author(s):  
Jong-Soo Kim ◽  
Ki-Taek Lee ◽  
Jae-Hong Kim ◽  
Soo-Jung Ha ◽  
Yong-Bin Im
Keyword(s):  
Experimental Study ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Single Phase ◽  
Small Diameter ◽  
Flow Distribution ◽  
Compact Heat Exchanger ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Pressure

In this paper an experimental study was performed for relation between two-phase pressure drop and flow distribution in compact heat exchanger using small diameter tubes. We performed the experimental study in non-heating mode. A test section was consisted of the horizontal header (circular tube: φ 5 mm × 80 mm) and 10 upward circular channels (φ 1.5 mm × 850 mm) using acrylic tube. Three different types of tube insertion depth were tested for the mass flux and inlet quality ranging from of 50–200 kg/m2s and 0.1–0.3, respectively. Air and water were used as the test fluids. Two-phase pressure drop of each channel and three type of distribution header was measured. As whole, single-phase and two-phase, pressure drop in rear channel is found to be lower than that in front channel. In conclusion, we can claim that principle of distribution is almost same pressure drop in each channel. Comparing pressure drop in branch tube with correlation equation, it was found that in single-phase flow, experimental value was 10% lower than Hagen-Poiseuille, Blasius equation (Eq. 40) in two-phase flow.

Numerical simulation of the fluid flow and heat transfer characteristics of microchannel heat exchangers with different reentrant cavities

2019 ◽  
Vol 29 (11) ◽  
pp. 4334-4348
Author(s):  
Minqiang Pan ◽  
Hongqing Wang ◽  
Yujian Zhong ◽  
Tianyu Fang ◽  
Xineng Zhong
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Content Type ◽  
Microchannel Heat Exchanger ◽  
Flow And Heat Transfer

Purpose With the increasing heat dissipation of electronic devices, the cooling demand of electronic products is increasing gradually. A water-cooled microchannel heat exchanger is an effective cooling technology for electronic equipment. The structure of a microchannel has great impact on the heat transfer performance of a microchannel heat exchanger. The purpose of this paper is to analyze and compare the fluid flow and heat transfer characteristic of a microchannel heat exchanger with different reentrant cavities. Design/methodology/approach The three-dimensional steady, laminar developing flow and conjugate heat transfer governing equations of a plate microchannel heat exchanger are solved using the finite volume method. Findings At the flow rate range studied in this paper, the microchannel heat exchangers with reentrant cavities present better heat transfer performance and smaller pressure drop. A microchannel heat exchanger with trapezoidal-shaped cavities has best heat transfer performance, and a microchannel heat exchanger with fan-shaped cavities has the smallest pressure drop. Research limitations/implications The fluid is incompressible and the inlet temperature is constant. Practical implications It is an effective way to enhance heat transfer and reduce pressure drop by adding cavities in microchannels and the data will be helpful as guidelines in the selection of reentrant cavities. Originality/value This paper provides the pressure drop and heat transfer performance analysis of microchannel heat exchangers with various reentrant cavities, which can provide reference for heat transfer augmentation of an existing microchannel heat exchanger in a thermal design.

The Influence of Header Design on Two-Phase Flow Distribution in Plate-Fin Heat Exchangers

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Zhe Zhang ◽  
Sunil Mehendale ◽  
Shengnan Lv ◽  
Hui Yuan ◽  
JinJin Tian
Keyword(s):  
Heat Exchanger ◽  
Water Flow ◽  
Heat Exchangers ◽  
Water Distribution ◽  
Single Phase ◽  
Two Phase Flow ◽  
Flow Distribution ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

Abstract Fluid flow maldistribution causes deterioration of heat transfer as well as pressure drop penalty in heat exchangers. A test bench was set up to investigate the effect of different header designs on air-water flow distribution in plate-fin heat exchangers (PFHX). Two-phase flow distribution was examined for air Reynolds numbers (ReG) of 28293542 and inlet qualities (x) of 46.3–64.0%. Two-phase flow distribution was seen to be more uneven in the heat exchanger in comparison with single-phase flow, the water distribution being more uneven than that of the air. For a fixed inlet quality, as the air flowrate was increased, the distribution of two-phase flow became increasingly nonuniform, showing a pattern similar to single-phase flow. Furthermore, the air distribution became more even, while the water flow became more unevenly distributed as the inlet quality increased. To mitigate the maldistribution, perforated plates were incorporated in the heat exchanger header. The improved headers significantly aided in distributing the two-phase flow more evenly. At ReG = 2829 and x = 46.3%, the heat exchanger effectiveness was expressed in terms of the unevenness in quality, Sx. The effectiveness decreased as the unevenness of the flow distribution was exacerbated, emphasizing the significance of uniform phase and flow distribution as a key element of heat exchanger design.

Multi-Physics Topology Optimization for Thermal-Flow Problems Applied to Additively Manufactured Heat Exchangers

2021 ◽  
Author(s):  
Tsz Ling Elaine Tang ◽  
Songtao Xia ◽  
Peter Rop ◽  
Steven de Wispelaere ◽  
Ramesh Subramanian ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Single Phase ◽  
Performance Metrics ◽  
Coupled Flow ◽  
Adjoint Sensitivity ◽  
Flow Topology ◽  
Two Phase ◽  
Manufacturing Technologies

Abstract Heat exchangers are often subjected to increasing demands on their efficiency with a reduced volumetric footprint. With the advancement in additive manufacturing technologies, topology optimization can be a viable strategy to derive novel designs to improve product performance. Topology optimization has been vastly investigated in the past few decades for structural designs. In this presentation, a thermo-flow topology optimization workflow was developed for heat exchanger applications which performs a multi-physics analysis (e.g. with coupled flow dynamics and heat transfer). In the thermo-flow topology optimization workflow, thermo-flow solver in STAR-CCM+ was utilized to evaluate thermal and flow performance metrics. Adjoint sensitivity was computed with the adjoint solver based on a defined objective function. The adjoint sensitivity was then used as an input to a method of moving asymptotes (MMA) optimizer to identify new designs. This integrated workflow is demonstrated through the design optimization for application to heat exchangers with single phase fluids in a dual flow arrangement. The multi-physics topology optimization enables objectives of different physics to be evaluated in a single optimization run. The major complicating factor compared to earlier optimization work on the gas turbine components, is the dual flow character of the problem that requires optimization on both sides of the heat exchanger. Future efforts on several individual flows involved in the heat exchange problem, as well as single phase versus two-phase flow phenomena will be discussed.

Numerical Simulation of a Microchannel Heat Exchanger Using Steady-State and Time-Dependent Solvers

2010 ◽  
Author(s):  
Thanhtrung Dang ◽  
Jyh-tong Teng
Keyword(s):  
Steady State ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Electronic Devices ◽  
Time Dependent ◽  
The Finite Element Method ◽  
Counter Flow ◽  
Microchannel Heat Exchanger ◽  
Good Agreement

Microchannel heat exchangers are employed for thermal management of electronic devices, IC circuits, etc. Simulation of microchannel heat exchangers using solver with the capability of dealing with steady-state and time-dependent conditions is carried out. The solver — COMSOL — was developed by COMSOL Multiphysics, Inc. using the finite element method. The pressure drop and heat transfer are two of the most important parameters in these devices. In this study, the results obtained from the numerical analyses were in good agreement with those obtained from the papers. In addition, using the same heat exchanger configuration, results obtained from numerical simulations of pressure drop and overall thermal resistance using the COMSOL indicated that those parameters are lower for the cases with parallel-flow than those with the counter-flow.

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