Significant Benefits of 3D Screen Printing for Manufacturing Micro-Channel Heat Exchangers

2018 ◽  
Vol 941 ◽  
pp. 2148-2153
Author(s):  
James Allen Zess ◽  
Martin Dressler
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
High Temperature ◽  
Heat Exchangers ◽  
Chemical Etching ◽  
Screen Printing ◽  
Micro Channel ◽  
Micro Channels ◽  
Nickel Based Alloy ◽  
Manufacturing Methods

Micro-channel heat exchangers (MCHXs) manufactured by Zess & Lin Industries provide highly effective heat transfer and are used in a growing number of critical applications. MCHXs consist of stainless steel or high temperature Nickel-based alloy plates with micro channels that are chemically etched or machined into each plate. These traditional extractive manufacturing methods of chemical etching and machining used in manufacturing MCHX plates are difficult and costly as a large percentage of expensive alloy is lost during manufacturing.

Design and Development of a Low-Cost, High Temperature Silicon Carbide Micro-Channel Recuperator

2005 ◽  
Author(s):  
Merrill A. Wilson ◽  
Kurt Recknagle ◽  
Kriston Brooks
Keyword(s):  
Heat Transfer ◽  
Silicon Carbide ◽  
High Temperature ◽  
Heat Exchanger ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Ceramic Materials ◽  
Micro Channel ◽  
Micro Channels ◽  
Micro Turbine

Typically, ceramic micro-channel devices are used for high temperature heat exchangers, catalytic reactors, electronics cooling, and processing of corrosive streams where the thermomechanical benefits of ceramic materials are desired. These benefits include: high temperature mechanical and corrosion properties and tailorable material properties such as thermal expansion, electrical conductivity and thermal conductivity. In addition, by utilizing Laminated Object Manufacturing (LOM) methods, inexpensive ceramic materials can be layered, featured and laminated in the green state and co-sintered to form monolithic structures amenable to mass production. In cooperation with the DOE and Pacific Northwest National Labs, silicon carbide (SiC) based micro-channel recuperator concepts are being developed and tested. The performance benefits of a high temperature, micro-channel heat exchanger are realized from the improved thermal efficiency of the high temperature cycles and the improved effectiveness of micro-channels for heat transfer. In designing these structures, the heat and mass transfer within the micro-channels are being analyzed with heat transfer models, computational fluid dynamics models and validated with experimental results. As an example, a typical micro-turbine cycle was modified and modeled to incorporate this ceramic recuperator and it was found that the overall thermal efficiency of the micro-turbine could be improved from about 27% to over 40%. Process improvements require technical advantages and cost advantages. These LOM methodologies have been based on well-proven industry standard processes where labor, throughput and capital estimates have been tested. Following these cost models and validation at the prototype scale, cost estimates were obtained. For the micro-turbine example, cost estimates indicate that the high-temperature SiC recuperator would cost about $200 per kWe. The development of these heat exchangers is multi-faceted and this paper focuses on the design optimization of a layered micro-channel heat exchanger, its performance testing, and fabrication development through LOM methodologies.

Design of a Ceramic Heat Exchanger for Sulfuric Acid Decomposition

2006 ◽  
Author(s):  
Merrill A. Wilson ◽  
Charles Lewinsohn ◽  
James Cutts ◽  
Valery Ponyavin
Keyword(s):  
Heat Transfer ◽  
Sulfuric Acid ◽  
High Temperature ◽  
Heat Exchanger ◽  
Ceramic Materials ◽  
Compact Heat Exchanger ◽  
Micro Channel ◽  
Micro Channels ◽  
Macro Scale ◽  
Chemical Cycle

It has been proposed that compact ceramic heat exchangers can be used for high temperature, corrosive applications. This paper discusses the design development of a micro-channel heat exchanger for the decomposition of sulfuric acid as part of the hydrogen producing sulfur iodine thermo-chemical cycle. Corrosion studies of candidate materials indicate that ceramic materials have superior corrosion and creep resistance under these high temperature, high acid concentration environments. This compact heat exchanger utilizes micro-channels to enhance the heat transfer while maintaining low pressure drops within the system. Through modular stacking of these micro-channel networks, a "shell and plate" configuration enables the processing of commercial-scale processes. The ceramic materials provide for long-life applications. The design of the micro-channel features captures the enhanced heat transfer characteristics at the micro-scale; the modular assembly permits the integration into macro-scale processes. As a case study, the thermal performance and the economics were investigated to determine the feasibility of this compact heat exchanger for the hydrogen producing sulfur iodine thermo-chemical cycle. The results of this design effort with its associated performance goals and development status will be reported.

Development and Analysis of Micro-Channel Heat Exchangers for Natural Gas Cooling

2015 ◽  
Author(s):  
S. Menon ◽  
H. Ganti ◽  
H. Wang ◽  
C. Hagen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Natural Gas ◽  
Heat Exchangers ◽  
System Performance ◽  
Ambient Air ◽  
Micro Channel ◽  
Cfd Models ◽  
Component Design ◽  
Micro Channels

Abundant availability and potential for lower CO2 emissions are drivers for increased utilization of natural gas in automotive engines for transportation applications. However scarce refueling resources for on-road vehicles impose an infrastructure limited barrier on natural gas use in transportation. A novel ‘bimodal’ engine which can operate in a compressor mode has been developed that allows on-board refueling of natural gas where available without the need for any supplemental device. Engine compression of natural gas however results in considerable heating of the gas which is undesirable from a system stand-point. Micro-channel heat exchangers have been developed to absorb heat from the natural gas using engine coolant and compressed air. This work presents the design and development of the micro-channel heat exchangers as well as a preliminary analysis of system performance. Design methodology for the heat exchanger was based on trade-off studies that correlated system performance with component design. Energy flows through the system are analyzed as a function of engine compression ratio, operating speed, charge flow rate, and ambient air and natural gas conditions. These results are further used to estimate heat transfer co-efficient and effectiveness of the micro-channel heat exchanger. Future work involves developing CFD models of the heat exchanger to obtain a detailed understanding of the conjugate heat transfer and fluid flow processes within the micro-channels.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Comparison of 30 Boiling and Condensation Correlations for Two-Phase Flows in Compact Plate-Fin Heat Exchangers

2017 ◽  
Author(s):  
Wenhai Li ◽  
Ken Alabi ◽  
Foluso Ladeinde
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Flow Boiling ◽  
Transfer Coefficients ◽  
Two Phase Flows ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
Heat Exchanger Design ◽  
Micro Channels ◽  
Vertical Tubes

Over the years, empirical correlations have been developed for predicting saturated flow boiling [1–15] and condensation [16–30] heat transfer coefficients inside horizontal/vertical tubes or micro-channels. In the present work, we have examined 30 of these models, and modified many of them for use in compact plate-fin heat exchangers. However, the various correlations, which have been developed for pipes and ducts, have been modified in our work to make them applicable to extended fin surfaces. The various correlations have been used in a low-order, one-dimensional, finite-volume type numerical integration of the flow and heat transfer equations in heat exchangers. The NIST’s REFPROP database [31] is used to account for the large variations in the fluid thermo-physical properties during phase change. The numerical results are compared with Yara’s experimental data [32]. The validity of the various boiling and condensation models for a real plate-fin heat exchanger design is discussed. The results show that some of the modified boiling and condensation correlations can provide acceptable prediction of heat transfer coefficient for two-phase flows in compact plate-fin heat exchangers.

A Study on the Strength under Pressure of Micro Heat Exchanger

2006 ◽  
Vol 326-328 ◽  
pp. 265-268
Author(s):  
Taek Joon Son ◽  
Young Shin Lee
Keyword(s):  
Stainless Steel ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Structural Analysis ◽  
Thin Plate ◽  
Thin Plates ◽  
Micro Channel ◽  
Design Guideline ◽  
Micro Heat Exchanger ◽  
Micro Channels

The strength of micro heat exchanger under pressure is studied in this paper. Micro heat exchanger is made with brazing technology. It is constructed of stainless steel thin plates with micro channels and in/out port for fluid flow. Micro channels in thin plates are formed by etching and all parts including thin plates are joined by brazing. The study on the strength under pressure is performed by structural analysis. For structural analysis, one layer of micro heat exchanger body is considered. It is composed of thin plate with micro channel and brazing filler which is used to join thin plates. This paper shows the tendency of stress behavior and gives design guideline of micro heat exchanger.

Coupled Heat Transfer and Hydraulic Modeling of an Experimental Printed Circuit Heat Exchanger Using Finite Element Methods

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Ian W. Jentz ◽  
Mark H. Anderson
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Heat Exchanger ◽  
Hydraulic Modeling ◽  
Design Tool ◽  
Micro Channel ◽  
Printed Circuit ◽  
Coupled Heat Transfer ◽  
Computational Overhead ◽  
Micro Channels

Abstract The Homogenized Heat Exchanger Thermohydraulic (HHXT) modeling environment has been developed to provide thermodynamic modeling of printed circuit heat exchangers (PCHEs). This finite element approach solves solid conduction and fluid thermohydraulics simultaneously, without the need to mesh the minuscule micro-channels of a PCHE. The model handles PCHE features such as headers, solid side walls, and channel inlet and outlet regions, in addition to the micro-channel core. The HHXT model resolves PCHE thermohydraulics using simple model definitions and minimum computational overhead, making it an ideal design tool. This work introduces the thermohydraulic model at the core of HHXT. The homogenization approach used in the model occupies a medium between simplified linear analyses of heat transfer within a PCHE and the brute force of a fully resolved finite element, or computational fluid dynamics, model. An example problem modeling an experimental PCHE is presented. The ability of the HHXT model to simulate fluid flow through a directional varying micro-channel core of two heat-exchanging streams is demonstrated. The HHXT model is being distributed for free within the research community.

Heat and Mass Transfer Design of a Silicon Carbide Micro-Channel Heat Exchanger

2003 ◽  
Author(s):  
Merrill A. Wilson ◽  
Michele Bullough ◽  
Kriston Brooks ◽  
Kurt Recknagle
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Unit Volume ◽  
Micro Channel ◽  
System Efficiency ◽  
Uniform Temperature ◽  
Power Cycles ◽  
Ceramic Recuperator ◽  
Improve Heat Transfer ◽  
Higher Temperature

Efficiency and emissions of advanced gas turbine power cycles can be improved by incorporating high-temperature ceramic heat exchangers. In cooperation with the DOE, a highly effective microchannel ceramic recuperator for a microturbine is under development. In this recuperator, the use of microchannel architecture will improve heat transfer and provide a more uniform temperature distribution. This will result in overall higher productivity per unit volume compared to conventional hardware. The use of ceramic for the recuperator will allow higher temperature operation than available in conventional microturbines. Based on a model for a typical microturbine, these changes may improve the overall system efficiency from about 27% to over 40%.

Numerical Analysis on Flow Characteristics of Anti-Gravity Flow

2011 ◽  
Author(s):  
Yan Li ◽  
Shuchao Zhang ◽  
Ning Mei
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Flow Characteristics ◽  
Gravity Flow ◽  
Radius Of Curvature ◽  
Micro Channel ◽  
Subcooled Boiling ◽  
Evaporation Heat ◽  
Micro Channels

Fluid flow phenomena in micro channels received wide attention due to its high heat transfer coefficient. As a new technique in the field of micro channel phase-change heat transfer, anti-gravity flow can drive fluid flow by capillary force and create enhanced evaporation heat transfer conditions by promoting the formation of an extended meniscus in the three-phase contact-line region. Resulting from the circumferential discrepancy of degree of superheat, the radius of curvature of intrinsic meniscus decreases rapidly as liquid rising up, leading to the formation of capillary pressure gradient. With the increase of heat flux, subcooled boiling occurs and micro-bubble appears at the bottom of the fluted tube. Under the action of buoyancy and drag force, the bubble rises along the channel and at the same time grows continually for the presence of superheat until its break. This paper focuses on the numerical study of flow characteristics of anti-gravity flow in the micro channel and the influence of bubble under the subcooled boiling circumstance. The results shows that bubble plays a positive role in the formation of anti-gravity flow and the analytical expressions are presented for the rising velocity of liquid, the contact angle and the curvature of the intrinsic meniscus, which are all influenced by heat flux, superheat temperature and the geometric parameters of the channel.

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