Enhanced Gas-Side Heat Transfer in Rectangular Micro-Honeycombs

2012 ◽  
Author(s):  
Shankar Krishnan ◽  
Steve Leith ◽  
Terry Hendricks
Keyword(s):  
Heat Transfer ◽  
Power Systems ◽  
Heat Exchangers ◽  
High Performance ◽  
Heat Transfer Performance ◽  
Low Cost ◽  
Transfer Performance ◽  
Thermo Electric ◽  
Transfer Resistance ◽  
Heat Transfer Augmentation

Gas and air-side heat transfer is ubiquitous throughout many technological sectors, including HVAC (heating, ventilating, and air conditioning) systems, thermo-electric power generators and coolers, renewable energy, electronics and vehicle cooling, and forced-draft cooling in the petrochemical and power industries. The poor thermal conductivity and low heat capacity of air causes air-side heat transfer to typically dominate heat transfer resistance even with the use of extended area structures. In this paper, we report design, analysis, cost modeling, fabrication, and performance characterization of micro-honeycombs for gas-side heat transfer augmentation in thermoelectric (TE) cooling and power systems. Semi-empirical model aided by experimental validation was undertaken to characterize fluid flow and heat transfer parameters. We explored a variety of polygonal shapes to optimize the duct shape for air-side heat transfer enhancement. Predictions using rectangular micro-honeycomb heat exchangers, among other polygonal shapes, suggest that these classes of geometries are able to provide augmented heat transfer performance in high-temperature energy recovery streams and low-temperature cooling streams. Based on insight gained from theoretical models, rectangular micro-honeycomb heat exchangers that can deliver high performance were fabricated and tested. High- and low-cost manufacturing prototype designs with different thermal performance expectations were fabricated to explore the cost-performance design domain. Simple metrics were developed to correlate heat transfer performance with heat exchanger cost and weight and define optimum design points. The merits of the proposed air-side heat transfer augmentation approach are also discussed within the context of relevant thermoelectric power and cooling systems.

Comparison of Heat Transfer Performance Between Smooth and Enhanced Heat Transfer Tubes

2019 ◽  
Author(s):  
David J. Kukulka ◽  
Wei Li ◽  
Rick Smith
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
High Performance ◽  
Heat Transfer Performance ◽  
Industrial Applications ◽  
Material Surface ◽  
Transfer Performance ◽  
Enhanced Heat Transfer ◽  
Enhanced Tubes ◽  
Smooth Tubes

Abstract Heat transfer enhancement is an important factor in obtaining energy efficiency improvements in all heat transfer applications. A numeric study was performed that compares the performance of heat exchangers using the Vipertex enhanced heat transfer tubes (model 1EHT) to the performance of heat exchangers that use smooth surface tubes and other enhanced tubes. Surface enhancement of the 1EHT tube is accomplished through the use of the primary dimple enhancement and a secondary background pattern made up of petal arrays. Utilization of enhanced heat transfer tubes is an effective method that is utilized in the development of high performance thermal systems. Vipertex™ tubes, have been designed and produced through material surface modifications that produce flow optimized heat transfer tubes that increase heat transfer performance. Current energy demands and the desire to increase efficiencies of systems have prompted the development of optimized enhanced heat transfer surfaces. Enhanced heat transfer tubes are widely used in many areas (refrigeration, air-conditioning, process, petrochemical, chemical, etc.) in order to reduce cost, create a smaller application footprint or increase production. A new type of enhanced heat transfer tube has been created; therefore it is important to investigate relevant heat exchanger designs using the Vipertex enhanced surface tube in industrial applications and compare that performance to smooth tubes and other enhanced tubes. Results include design characteristics and performance predictions using the design simulations produced using HTRI Exchanger Suite (2016). Performance for all cases considered using the Vipertex tube predicted over design when compared to a smooth tube design. Vipertex 1EHT tubes produced enhanced heat transfer and cost efficient designs. In some of the case studies the 1EHT tubes produce an overdesign that is more than 35%, while smooth tubes produce an underdesign and other low fin tubes produce overdesign but not as large as the 1EHT tubes.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

The Curvature Effect on the Heat Transfer at the End of a Bayonet Tube With Laminar Flows

2004 ◽  
Author(s):  
F. Sun ◽  
H. Li ◽  
J. Drummond ◽  
G.-X. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Average Nusselt Number ◽  
Heat Transfer Performance ◽  
Laminar Flows ◽  
Transfer Performance ◽  
Curvature Effect ◽  
Flow And Heat Transfer ◽  
Cooling Agent ◽  
Annular Section

Bayonet tubes, simple refluent heat exchangers, are widely used to heat or cool a media when the heating/cooling agent is readily accessible from one side only. Many studies have been conducted to evaluate the heat transfer performance of bayonet tubes. The majority of these studies focus on the heat transfer in the annular section and little on the end surface. This paper presents a numerical simulation of the laminar flow and heat transfer in a bayonet tube. The simulation is first validated by the experimental data in the literature. The flow and heat transfer in bayonet tubes are then investigated with both flat and curved end surfaces. Both local and average Nusselt number on the end surfaces are calculated under various Re and geometry conditions. Effect of the end surface curvature is studied by comparing the performances of the flat and curved ended bayonet tubes.

Ultra-Compact Micro-Scale Heat Exchanger for Advanced Thermal Management in Datacenters

2020 ◽  
Author(s):  
Raffaele L. Amalfi ◽  
Todd Salamon ◽  
Filippo Cataldo ◽  
Jackson B. Marcinichen ◽  
John R. Thome
Keyword(s):  
Heat Transfer ◽  
Form Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Two Phase ◽  
Pressure Drops ◽  
Cooling Technology ◽  
Cooling Loop ◽  
Two Phase Cooling

Abstract The present study is focused on the experimental characterization of two-phase heat transfer performance and pressure drops within an ultra-compact heat exchanger (UCHE) suitable for electronics cooling applications. In this specific work, the UCHE prototype is anticipated to be a critical component for realizing a new passive two-phase cooling technology for high-power server racks, as it is more compact and lighter weight than conventional heat exchangers. This technology makes use of a novel combination of thermosyphon loops, at the server-level and rack-level, to passively cool an entire rack. In the proposed two-phase cooling technology, a smaller form factor UCHE is used to transfer heat from the server-level thermosyphon cooling loop to the rack-level thermosyphon cooling loop, while a larger form factor UCHE is used to reject the total heat from the server rack into the facility-level cooling loop. The UCHE is composed of a double-side-copper finned plate enclosed in a stainless steel enclosure. The geometry of the fins and channels on both sides are optimized to enhance the heat transfer performance and flow stability, while minimizing the pressure drops. These features make the UCHE the ideal component for thermosyphon cooling systems, where low pressure drops are required to achieve high passive flow circulation rates and thus achieve high critical heat flux values. The UCHE’s thermal-hydraulic performance is first evaluated in a pump-driven system at the Laboratory of Heat and Mass Transfer (LTCM-EPFL), where experiments include many configurations and operating conditions. Then, the UCHE is installed and tested as the condenser of a thermosyphon loop that rejects heat to a pumped refrigerant system at Nokia Bell Labs, in which both sides operate with refrigerants in phase change (condensation-to-boiling). Experimental results demonstrate high thermal performance with a maximum heat dissipation density of 5455 (kW/m3/K), which is significantly larger than conventional air-cooled heat exchangers and liquid-cooled small pressing depth brazed plate heat exchangers. Finally, a thermal performance analysis is presented that provides guidelines in terms of heat density dissipations at the server- and rack-level when using passive two-phase cooling.

Research on Chinese Codes and Standards of Heat Transfer Performance Testing for Heat Exchangers

2020 ◽  
Author(s):  
Bin Ren ◽  
Xiaoying Tang ◽  
Facai Ren ◽  
Jibing Wang ◽  
Bofeng Bai
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Performance Test ◽  
Heat Transfer Performance ◽  
Performance Testing ◽  
Test Methods ◽  
Transfer Performance ◽  
Factors Affecting ◽  
Nonlinear Fitting ◽  
Test Standards

Abstract Heat exchanger is a device that transfers heat between hot and cold fluids. Due to the different size and type, the actual heat transfer performance is usually not the same as the design value. Meanwhile, various heat exchangers using new types of heat transfer elements have emerged, bringing the difficulty to obtain the heat transfer performance by only theoretical calculation. Therefore, studying test methods and developing test standards for heat exchangers have become the research focus in many countries. In this paper, the basic principles of various performance test methods are firstly introduced, including Wilson plot method, equal Reynolds number method and nonlinear fitting method. Then the restrictions on the use of these methods and the factors affecting the test results are analyzed. Finally, the Chinese codes and standards of performance testing for heat exchangers are listed, including JB/T 10379-2002, GB/T 27698-2011 and TSG R0010-2019. The test methods used in GB/T 27698 are described in detail. The results show that GB 27698 mainly focus on the specification of testing systems and procedures and can test heat transfer performance of almost all types of heat exchangers in industry under different heat transfer modes. However, there are lack of formulas and methods for calculating uncertainty of testing results.

State of the art on flow and heat transfer performance of compact fin-and-tube heat exchangers

2019 ◽  
Vol 139 (4) ◽  
pp. 2739-2768 ◽  
Author(s):  
A. Y. Adam ◽  
A. N. Oumer ◽  
G. Najafi ◽  
M. Ishak ◽  
M. Firdaus ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
State Of The Art ◽  
Transfer Performance ◽  
Flow And Heat Transfer

Study on the Conical Spiral Tube Bundle Heat Exchangers with Pulsation Flow Generator Structure

2011 ◽  
Vol 143-144 ◽  
pp. 698-702 ◽  
Author(s):  
Meng Ran Ge ◽  
Ke Yan ◽  
Pei Qi Ge ◽  
Jun Gao
Keyword(s):  
Heat Transfer ◽  
Natural Frequency ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Tube Bundle ◽  
Elastic Tube ◽  
Transfer Performance ◽  
Spiral Tube ◽  
Flow Generator ◽  
Planar Elastic Tube Bundle

Elastic tube bundles are universally used in heat transfer enhancement by flow-induced vibration in heat exchangers, and the study of the heat transfer performance is of importance. The structure of conical spiral tube bundle heat exchanger was introduced first, and the structure of pulsation flow generator was also introduced. The frequency of pulsation flow was discussed. Finally, in condition of same shell side diameter, the heat transfer and natural frequency of the conical spiral tube bundle were compared with the planar elastic tube bundle. The results show that the natural frequency of conical spiral tube bundle was smaller, the heat transfer performance of conical spiral tube bundle was better than the planar elastic tube bundle.

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