Fluid Flow and Heat Transfer at Micro- and Meso-Scales With Application to Heat Exchanger Design

2000 ◽  
Vol 53 (7) ◽  
pp. 175-193 ◽  
Author(s):  
S. S. Mehendale ◽  
A. M. Jacobi ◽  
R. K. Shah
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermal Systems ◽  
Structured Surfaces ◽  
Compact Heat Exchangers ◽  
Heat Exchanger Design ◽  
Flow And Heat Transfer ◽  
The Status ◽  
Material Volume ◽  
Modern Technologies

By their very nature, compact heat exchangers allow an efficient use of material, volume, and energy in thermal systems. These benefits have driven heat exchanger design toward higher compactness, and the trend toward ultra-compact designs will continue. Highly compact surfaces can be manufactured using micro-machining and other modern technologies. In this paper, unresolved thermal-hydraulic issues related to ultra-compact designs are discussed, and the status of the technologies required for the production of ultra-compact structured surfaces is summarized. This review article includes 67 references.

A Heuristic for Designing Hybrid Compact Heat Exchangers for Nuclear Applications

2021 ◽  
Author(s):  
Venkata Rajesh Saranam ◽  
Peter Carter ◽  
Kyle Rozman ◽  
Ömer Dogan ◽  
Brian K. Paul
Keyword(s):  
Heat Exchanger ◽  
Diffusion Bonding ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
Nuclear Industry ◽  
Compact Heat Exchangers ◽  
Bonding Parameters ◽  
Heat Exchanger Design ◽  
Creep Fatigue ◽  
Gen Iv

Abstract Hybrid compact heat exchangers (HCHEs) are a potential source of innovation for intermediate heat exchangers in nuclear industry, with HCHEs being designed for Gen-IV nuclear power applications. Compact heat exchangers are commonly fabricated using diffusion bonding, which can provide challenges for HCHEs due to resultant non-uniform stress distributions across hybrid structures during bonding, leading to variations in joint properties that can compromise performance and safety. In this paper, we introduce and evaluate a heuristic for determining whether a feasible set of diffusion bonding conditions exist for producing HCHE designs capable of meeting regulatory requirements under nuclear boiler and pressure vessel codes. A diffusion bonding model for predicting pore elimination and structural analyses are used to inform the heuristic and a heat exchanger design for 316 stainless steel is used to evaluate the efficacy of the heuristic to develop acceptable diffusion bonding parameters. A set of diffusion bonding conditions were identified and validated experimentally by producing various test coupons for evaluating bond strength, ductility, porosity, grain size, creep rupture, creep fatigue and channel deviation. A five-layer hybrid compact heat exchanger structure was fabricated and tensile tested demonstrating that the bonding parameters satisfy all criteria in this paper for diffusion bonding HCHEs with application to the nuclear industry.

Air Cooled Compact Heat Exchanger Design for Avionics Thermal Management Using Published Test Data

2003 ◽  
Author(s):  
George Hall ◽  
James Marthinuss
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Thermal Management ◽  
Test Data ◽  
Heat Exchangers ◽  
Optimized Design ◽  
Compact Heat Exchanger ◽  
Compact Heat Exchangers ◽  
Heat Exchanger Design

This paper will discuss air-cooled compact heat exchanger design using published data. Kays & London’s “Compact Heat Exchangers” [1] contains measured heat transfer and pressure drop data on a variety of circular and rectangular passages including circular tubes, tube banks, straight fins, louvered fins, strip or lanced offset fins, wavy fins and pin fins. While “Compact Heat Exchangers” is the benchmark for air cooled heat exchanger test data it makes no attempt to summarize the results or steer the thermal designer to an optimized design based on the different factors or combination of heat transfer, pressure drop, size, weight, or even cost. Using this reduced data and the analytical solutions provided highly efficient compact heat exchangers could be designed. This paper will guide a thermal engineer toward this optimized design without having to run trade studies on every possible heat exchanger design configuration. Typical applications of published fin data in the aerospace and military electronics include electronics cold plates, card rack walls and air-to-air heat exchangers using fan driven and ECS driven air. Airborne electronics often require extremely dense packaging techniques to fit all the required functions into the available volume. While leaving little room for cooling hardware this also drives power densities up to levels (20 W/sq-cm) that require highly efficient heat transfer techniques. Several design issues are discussed including pressure drop, heat transfer, compactness, axial conduction, flow distribution and passage irregularities (bosses). Comparisons between fin performance are made and conclusions are drawn about the applicability of each type of fin to avionics thermal management.

Development of a Compact Primary Heat Exchanger for a Molten Salt Reactor

2011 ◽  
Author(s):  
Matthew Lippy ◽  
Mark Pierson
Keyword(s):  
Heat Exchanger ◽  
Molten Salt ◽  
Heat Exchangers ◽  
Nuclear Industry ◽  
Hydrodynamic Performance ◽  
Molten Salt Reactor ◽  
Compact Heat Exchangers ◽  
Heat Exchanger Design ◽  
Fuel Salt ◽  
Shell And Tube

The first Molten Salt Reactor (MSR) was designed and tested at Oak Ridge National Laboratory (ORNL) in the 1960’s, but recent technological advancements now allow for new components, such as heat exchangers, to be created for the next generation of MSR’s and molten salt-cooled reactors. The primary (fuel salt-to-secondary salt) heat exchanger (PHX) design has been largely ignored up to this point; however, it is shown here that modern compact heat exchangers have the potential to make dramatic improvements over traditional shell-and-tube designs. Compact heat exchangers provide a higher effectiveness and more efficient use of material that offer a more cost-effective alternative to the massive, more expensive heat exchangers planned for the MSR. While this paper focuses on the application of compact heat exchangers on a Molten Salt Reactor, many of the analyses and results are similarly applicable to other fluid-to-fluid heat exchangers. The heat exchanger design in this study seeks to find a middle-ground between the dependable shell-and-tube design and the ultra-efficient, ultra-compact designs such as the Printed Circuit Heat Exchanger being developed today. Complex channel geometries and micro-scale dimensions in modern compact heat exchangers do not allow routine maintenance to be performed by standard procedures, so extended surfaces will be omitted and hydraulic diameters will be kept in the minichannel regime (minimum channel dimension between 200 μm and 3 mm) to allow for high-frequency eddy current inspection methods to be developed. Rather than using a “checkerboard” channel pattern, which requires complex header designs among other design challenges, row composition is homogeneous, and the borders between adjoining channels are removed to provide high aspect ratio rectangular channel cross-sections. Various plant layouts of smaller heat exchanger banks in a “modular” design are introduced, and the feasibility of casting such modules is assumed to be possible for the purposes of this research. FLUENT was used within ANSYS Workbench to find optimized heat transfer and hydrodynamic performance for straight-channel designs with two molten salts acting in pure counter-flow. Limiting the pressure drop to roughly that of ORNL’s Molten Salt Breeder Reactor’s shell-and-tube design, the compact heat exchanger design of interest in this study will lessen volume requirements, lower fuel salt volume, and decrease material usage. Compact heat exchangers have shown commercial feasibility in several industries but have yet to be assimilated into the nuclear industry. This intermediately-sized compact minichannel heat exchanger demonstrates that such a heat exchanger is viable for further testing. The original design of the MSR was an engineering marvel over 60 years ago, but several of its key components, namely the intermediate heat exchanger, must be updated in order for the MSR to reach its full potential.

scholarly journals A Review on The CFD Analysis of Nano Water Fluid On Helically Coiled Double Tube Heat Exchanger

2019 ◽  
Vol 5 (10) ◽  
pp. 3
Author(s):  
Sunil Kumar ◽  
Ravindra Mohan
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Future Research ◽  
Thermal Systems ◽  
Tube Heat Exchanger ◽  
Compact Heat Exchangers ◽  
Shell And Tube ◽  
Double Pipe ◽  
Nano Fluids ◽  
Pipe Heat

Heat exchanger is an important device which is used in thermal systems in many industrial fields. Nano fluids are recently employed as coolants to improve the efficacy of heat exchangers. Regarding unique characteristics of Nano fluids, research studies in this area have witnessed a remarkable growth. Latest investigations conducted on use of Nano fluids in heat exchangers including those carried out on plate heat exchangers, double pipe heat exchangers, shell and tube heat exchangers, and compact heat exchangers are reviews and summarized. Meanwhile, some very interesting aspects of Nano fluids in combination with heat exchangers are presented.  The challenges and prospects for future research are presented in this paper.

scholarly journals Study of the Performance of a Novel Radiator with Three Inlets and One Outlet Based on Topology Optimization

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 594
Author(s):  
Tao Zhou ◽  
Bingchao Chen ◽  
Huanling Liu
Keyword(s):  
Topology Optimization ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Exchange Capacity ◽  
Numerical Results ◽  
Fluid Temperature ◽  
Channel Depth ◽  
Goal Model ◽  
Flow And Heat Transfer

In recent years, in order to obtain a radiator with strong heat exchange capacity, researchers have proposed a lot of heat exchangers to improve heat exchange capacity significantly. However, the cooling abilities of heat exchangers designed by traditional design methods is limited even if the geometric parameters are optimized at the same time. However, using topology optimization to design heat exchangers can overcome this design limitation. Furthermore, researchers have used topology optimization theory to designed one-to-one and many-to-many inlet and outlet heat exchangers because it can effectively increase the heat dissipation rate. In particular, it can further decrease the hot-spot temperature for many-to-many inlet and outlet heat exchangers. Therefore, this article proposes novel heat exchangers with three inlets and one outlet designed by topology optimization to decrease the fluid temperature at the outlet. Subsequently, the effect of the channel depth on the heat exchanger design is also studied. The results show that the type of exchanger varies with the channel depth, and there exists a critical depth value for obtaining the minimum substrate temperature difference. Then, the flow and heat transfer performance of the heat exchangers are numerically investigated. The numerical results show that the heat exchanger derived by topology optimization with the minimum temperature difference as the goal (Model-2) is the best design for flow and heat transfer performance compared to other heat sink designs, including the heat exchanger derived by topology optimization having the average temperature as the goal (Model-1) and conventional straight channels (Model-3). The temperature difference of Model-1 can be reduced by 37.5%, and that of Model-2 can be decreased by 62.5% compared to Model-3. Compared with Model-3, the thermal resistance of Model-1 can be reduced by 21.86%, while that of Model-2 can be decreased by 47.99%. At room temperature, we carried out the forced convention experimental test for Model-2 to measure its physical parameters (temperature, pressure drop) to verify the numerical results. The error of the average wall temperature between experimental results and simulation results is within 2.6 K, while that of the fluid temperature between the experimental and simulation results is within 1.4 K, and the maximum deviation of the measured Nu and simulated Nu was less than 5%. This indicated that the numerical results agreed well with the experimental results.

Basis of the Tubesheet Heat Exchanger Design Rules Used in the French Pressure Vessel Code

1992 ◽  
Vol 114 (1) ◽  
pp. 124-131 ◽  
Author(s):  
F. Osweiller
Keyword(s):  
Heat Exchanger ◽  
Pressure Vessel ◽  
Heat Exchangers ◽  
Tube Bundle ◽  
Outer Edge ◽  
Design Rules ◽  
Effective Elastic Constants ◽  
Heat Exchanger Design ◽  
Solid Plate ◽  
Main Basis

For about 40 years most tubesheet exchangers have been designed according to the standards of TEMA. Partly due to their simplicity, these rules do not assure a safe heat-exchanger design in all cases. This is the main reason why new tubesheet design rules were developed in 1981 in France for the French pressure vessel code CODAP. For fixed tubesheet heat exchangers, the new rules account for the “elastic rotational restraint” of the shell and channel at the outer edge of the tubesheet, as proposed in 1959 by Galletly. For floating-head and U-tube heat exchangers, the approach developed by Gardner in 1969 was selected with some modifications. In both cases, the tubesheet is replaced by an equivalent solid plate with adequate effective elastic constants, and the tube bundle is simulated by an elastic foundation. The elastic restraint at the edge of the tubesheet due the shell and channel is accounted for in different ways in the two types of heat exchangers. The purpose of the paper is to present the main basis of these rules and to compare them to TEMA rules.

Numerical Investigation on the Characteristic of the Reverse Flow Phenomenon in a Z-Type Parallel Compact Heat Exchanger With Large Number of Tubes

2018 ◽  
Author(s):  
Jian Zhou ◽  
Ming Ding ◽  
Haozhi Bian ◽  
Yinxing Zhang ◽  
Zhongning Sun
Keyword(s):  
Heat Exchanger ◽  
Pressure Distribution ◽  
Coming Out ◽  
Heat Exchangers ◽  
Cooling System ◽  
Reverse Flow ◽  
Flow Distribution ◽  
Flow Phenomenon ◽  
Compact Heat Exchangers ◽  
Geometry Design

The parallel compact heat exchangers have been widely applied in the various fields such as heat exchangers in chemical engineering, the solar collector, fuel cells and the passive removal heat exchanger in passive containment cooling system (PCCS), etc. The heat exchangers in the PCCS removes out the heat brought by the steam coming out from the broken reactor or primary cooling system. Therefore, the performance of the passive containment cooling system heat exchanger (PCCS HX) will greatly influence the safety and integrity of the containment. In previous investigations on the parallel compact heat exchangers, attentions are focused on the pressure distribution and flow distribution in the heat exchangers. A bad flow distribution in the heat exchanger will reduce the heat performance. More seriously, the coolant in some tubes may boils and the tubes will be overheated, resulting in explosion of tubes. Therefore, the characteristic of pressure distribution and the flow distribution should be investigated for a uniform flow distribution. In the past studies of the compact heat exchangers, the numbers of tube are almost under 72 which is relatively small, while the number of tubes PCCS HX is usually over than 100. And the pressure distribution in compact heat exchangers is assumed that the pressure recovery plays a leading role. However, the more numbers of tube will bring more flow maldistribution, if the geometry design is selected inappropriately. The reverse flow may occur in the heat exchanger, which means that in some tubes, the coolant flows from the tube outlet to the inlet. This phenomenon of reverse flow have never been mentioned in previous studies. The occurrence of the reverse flow will significantly decrease the performance of the heat exchanger and cause a bad influence on the safety of the containment. In the PCCS, the Z-type heat exchanger is one of the choice of PCCS HX (heat exchanger) design. Therefore, the present study focus on the characteristic of reverse flow phenomenon in Z-type heat exchangers. The pressure distribution and the flow distribution have been separately investigated deeply. The conclusion of this study will provide a guide to the geometry design of the PCCS HX with large number of tubes.

A Survey of Important Auxiliary Equations for Selected Compact Heat Exchanger

2005 ◽  
Author(s):  
Richard G. Carranza
Keyword(s):  
Heat Exchanger ◽  
Surface Area ◽  
Heat Exchangers ◽  
Volume Ratio ◽  
Compact Heat Exchanger ◽  
Fin Efficiency ◽  
Compact Heat Exchangers ◽  
Central Location

Important auxiliary equations are presented that are typically used in compact heat exchanger research. These relationships are presented only for selected compact heat exchangers — bare pipe, helically finned pipe, plate finned pipe, spined pipe, and plate exchangers. The equations primarily address issues relating to heat exchanger geometry, surface area to volume ratio, and fin efficiency. Furthermore, they are organized in a systematic manner and consolidated in one central location for easy reference.

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