Roller Profiling for Shaping Corrugated Profiles on the Heat Exchanger Tape for Wind Tunnels

2021 ◽  
pp. 16-27
Author(s):  
Yu.V. Shchipkova ◽  
A.Yu. Popov
Keyword(s):  
Plastic Deformation ◽  
Heat Exchanger ◽  
Contact Pressure ◽  
Heat Exchangers ◽  
Wind Tunnels ◽  
Regenerative Heat ◽  
Elastic Aftereffect ◽  
Study Results ◽  
Profile Correction ◽  
Profiling Techniques

The efficiency of regenerative heat exchangers with heat-accumulating nozzles made of rolled corrugated tapes depends on the profile of their corrugation. It is technologically difficult to obtain corrugations of a given shape by copying --- stamping. It is technically more expedientto form such a profile by rolling between two rollers. The contact area is smaller, and the contact pressure is significantly higher. In this case, the shape and accuracy of the tape profile are determined by the accuracy of calculation and manufacturing of the profile of the rollers. The length of the profiling zone and the contact pressure depend on the diameter of the rollers. To apply the known profiling techniques when calculating the corrugated profile of the rollers, it is necessary to find the position of the centroid. However, the difficulty is in the tape between the rollers whose thickness cannot be neglected. Therefore, the problem is solved by rolling the roller and the rail smooth, where the tape with a profile formed on it is considered as a rail. The paper introduces a technique of roller profiling taking into account the above factors. When profiling the rollers, the springing of the tape, i.e., elastic aftereffect of plastic deformation, is taken into account. The suitable diameter of the rollers has been determined. The study results in a method developed for calculating the rollers corrugation profile, taking into account the established parameters, i.e., diameters of the centroids and rollers, and the rollers teeth profile correction value, depending on the tape springing during rolling

scholarly journals The influence of main parameters of regenerative heat exchanger on its energy efficiency

2020 ◽  
Vol 178 ◽  
pp. 01024
Author(s):  
Nikolay Monarkin ◽  
Anton Sinitsyn ◽  
Mikhail Pavlov ◽  
Timur Akhmetov
Keyword(s):  
Energy Efficiency ◽  
Heat Capacity ◽  
Heat Exchanger ◽  
Wall Thickness ◽  
Thermal Energy ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Regenerative Heat ◽  
Flow Through ◽  
Geometric Length

The influence of various parameters of stationary switching regenerative heat exchangers used for ventilation on its thermal efficiency was studied. Considered are the geometric (length, diameter and wall thickness of a single equivalent nozzle channel), thermophysical (density and heat capacity of the nozzle material) and operation (air flow through the regenerator and the time of one stage of accumulation/regeneration of thermal energy) parameters.

Assessment of ASME Code Examinations on Regenerative, Letdown and Residual Heat Removal Heat Exchangers

2005 ◽  
Author(s):  
S. R. Gosselin ◽  
F. A. Simonen ◽  
S. E. Cumblidge ◽  
G. A. Tinsley ◽  
B. Lydell ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Power Plants ◽  
National Laboratory ◽  
Operating Experience ◽  
Heat Removal ◽  
Pacific Northwest National Laboratory ◽  
Regenerative Heat ◽  
Asme Code ◽  
Residual Heat

Inservice inspection requirements for pressure retaining welds in the regenerative, letdown, and residual heat removal heat exchangers are prescribed in Section XI Articles IWB and IWC of the ASME Boiler and Pressure Vessel Code. Accordingly, volumetric and/or surface examinations are performed on heat exchanger shell, head, nozzle-to-head, and nozzle-to-shell welds. Inspection difficulties associated with the implementation of these Code-required examinations have forced operating nuclear power plants to seek relief from the U.S. Nuclear Regulatory Commission. The nature of these relief requests are generally concerned with metallurgical factors, geometry, accessibility, and radiation burden. Over 60% of licensee requests to the NRC identify significant radiation exposure burden as the principal reason for relief from the ASME Code examinations on regenerative heat exchangers. For the residual heat removal heat exchangers, 90% of the relief requests are associated with geometry and accessibility concerns. Pacific Northwest National Laboratory was funded by the NRC Office of Nuclear Regulatory Research to review current practice with regard to volumetric and/or surface examinations of shell welds of letdown heat exchangers, regenerative heat exchangers, and residual (decay) heat removal heat exchangers. Design, operating, common preventative maintenance practices, and potential degradation mechanisms were reviewed. A detailed survey of domestic and international PWR-specific operating experience was performed to identify pressure boundary failures (or lack of failures) in each heat exchanger type and NSSS design. The service data survey was based on the PIPExp® database and covers PWR plants worldwide for the period 1970–2004. Finally a risk assessment of the current ASME Code inspection requirements for residual heat removal, letdown, and regenerative heat exchangers was performed. The results were then reviewed to discuss the examinations relative to plant safety and occupational radiation exposures.

Effects of Partial Cooling on Tightness of Heat Exchanger Girth Flange

2017 ◽  
Author(s):  
Kyohei Takahashi ◽  
Toshikazu Miyashita ◽  
Shunji Kataoka ◽  
Yoshiaki Uno ◽  
Takuya Sato
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Temperature Distribution ◽  
Contact Pressure ◽  
Heat Exchangers ◽  
Liquid Level ◽  
Design Codes ◽  
Key Characteristics ◽  
Present Design

For the girth flange of heat exchangers, the circumferential temperature distribution of shell and connecting flange due to inside fluid will affect tightness of the girth flange, however this effect is not considered in present design codes. It is important to know the key characteristics of flange tightness to minimize the risk of leakage. In past studies, the effects of circumferential temperature distribution on flange tightness were investigated at high temperature operations. The effects of partial cooling on flange tightness might be severer than circumferential high temperature distribution. In this paper, the effects of partial cooling on flange tightness were studied. The flange tightness was evaluated by wideness of partially cooled region (liquid level) of heat exchanger and gasket recovery characteristics parametrically. Based on these studies, it was concluded that the gasket contact pressure was decreased by the partial cooling of heat exchanger and the effects of the above mentioned factors were summarized quantitatively.

Limitations of Additive Manufacturing on Microfluidic Heat Exchanger Components

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Yenny Rua ◽  
Russell Muren ◽  
Shanon Reckinger
Keyword(s):  
Plastic Deformation ◽  
Natural Convection ◽  
Additive Manufacturing ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Structural Integrity ◽  
Microfluidic Channel ◽  
Microfluidic Channels ◽  
And Performance

This work describes the testing of microfluidic components created using additive manufacturing. An Objet Eden 250 was used to create microfluidic channel test coupons with passages ranging from 0.5 to 3.0 mm and wall thicknesses ranging from 0.032 to 0.5 mm. Coupons were cleaned and tested under flow to examine structural integrity. Microfluidic channels with wall thicknesses down to 0.032 mm could be printed, cleaned, and tested successfully, although plastic deformation was observed in coupons with wall thicknesses below 0.1 mm. Given these limits, additive manufacturing based microfluidic heat exchangers (HXs) offer cost and performance benefits in natural convection HX applications.

Technical Basis for Revision of Inspection Requirements for Regenerative and Residual Heat Exchangers

2006 ◽  
Author(s):  
Warren Bamford ◽  
Bruce Bishop ◽  
Richard Haessler ◽  
Mark Bowler
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Ultrasonic Inspection ◽  
Regenerative Heat ◽  
Flaw Tolerance ◽  
Nuclear Plants ◽  
History Of ◽  
Technical Basis ◽  
Very High ◽  
Residual Heat

Section XI imposed volumetric inservice inspection requirements on heat exchangers in nuclear plants after most of this equipment was designed and installed. Consequently the equipment was not designed for ultrasonic examination, and in some cases such volumetric examination is not justified. The man-rem dose received from the ultrasonic inspection of some of these components is very high, and there are no known mechanisms of degradation; thus, the volumetric inspection serves no useful purpose. With the use of the newly approved code case, N706, volumetric and surface inspection of the regenerative and residual heat exchangers in PWR plants may be replaced with a visual inspection. These two heat exchangers have high irradiation fields, and both have a number of complicated weld geometries that are difficult to inspect. The regenerative heat exchanger provides preheat for the normal charging water going into the reactor coolant system (RCS). The residual heat exchanger is designed to cool the RCS during plant shut down operations. The technical basis for changing these inspection requirements was derived from four fundamental arguments: 1. The heat exchangers were carefully constructed to nuclear quality requirements. 2. They were inspected during construction, and then during service, and there is no history of degradation. 3. The flaw tolerance of the components is very high, since their duty cycle is mild, and they are constructed of stainless steel. 4. The risk is not significantly changed by replacement of the examinations with visual examinations. This paper will describe in detail the technical arguments under each of these topics, which together form the basis for the code case.

scholarly journals Review of Design and Modeling of Regenerative Heat Exchangers

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 759
Author(s):  
Bohuslav Kilkovský
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Fixed Bed ◽  
Packed Bed ◽  
Regenerative Heat ◽  
Adequate Accuracy ◽  
Proper Design ◽  
Bed Material ◽  
The Heat Transfer Coefficient

Heat regenerators are simple devices for heat transfer, but their proper design is rather difficult. Their design is based on differential equations that need to be solved. This is one of the reasons why these devices are not widely used. There are several methods for solving them that were developed. However, due to the time demands of calculation, these models did not spread too much. With the development of computer technology, the situation changed, and these methods are now relatively easy to apply, as the calculation does not take a lot of time. Another problem arises when selecting a suitable method for calculating the heat transfer coefficient and pressure drop. Their choice depends on the type of packed bed material, and not all available computational equations also provide adequate accuracy. This paper describes the so-called open Willmott methods and provides a basic overview of equations for calculating the regenerative heat exchanger with a fixed bed. Based on the mentioned computational equations, it is possible to create a tailor-made calculation procedure of regenerative heat exchangers. Since no software was found on the market to design regenerative heat exchangers, it had to be created. An example of software implementation is described at the end of the article. The impulse to create this article was also to broaden the awareness of regenerative heat exchangers, to provide designers with an overview of suitable calculation methods and, thus, to extend the interest and use of this type of heat exchanger.

Effect of Face-Area Ratio on Heat-Exchanger Pressure Drops, Size and Weight

2009 ◽  
Author(s):  
David Gordon Wilson
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Short Circuit ◽  
Design Guidelines ◽  
Area Ratio ◽  
Regenerative Heat ◽  
Pressure Drops ◽  
Face Area ◽  
Significant Difference

Designers of heat exchangers of all types normally have several degrees of freedom even while meeting the specified effectiveness exactly. One freedom is that of choosing the face-area ratios for the two (or more) fluids. A principal reason for choosing face-area ratio is to arrive at desired pressure drops for the fluids. The lowest pressure drop is not always beneficial: a low pressure drop can produce highly non-uniform flow that would degrade heat-exchanger performance. Obviously a high pressure drop penalizes system performance directly. In this paper it is shown that choosing face-area ratio is a good tool up to a point, one at which penalties in the form of increased size and cost of the overall heat exchanger begin to outweigh the benefits. This paper reports studies on the effects of choosing face-area ratios on rotary regenerative heat exchangers, but most results are applicable to fixed-surface recuperative heat exchangers also. However, one significant difference between the two types is that gas-turbine regenerators have short flow lengths, the thickness of the disk or drum. A short flow length is a virtue, because it reduces the regenerator disk volume and mass. But the disk thickness must not be allowed to be reduced to the point where there is substantial “short-circuit” thermal conduction between the hot and cold faces of a regenerator. These and other aspects of heat-exchanger design are explored in general and by means of examples, and design guidelines are suggested.

scholarly journals Determination of rolling forces of corrugated profiles on stainless belt of heat exchanger for wind tunnels

2021 ◽  
Vol 5 (2) ◽  
pp. 106-112
Author(s):  
Yu. V. Shchipkova ◽  
◽  
A. Yu. Popov ◽  
Yu. A. Rogoza ◽  
D. A. Kormakov ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Storage ◽  
Wind Tunnels ◽  
Milling Machine ◽  
Force Measurements ◽  
Regenerative Heat ◽  
Steel Strips ◽  
Effective Form ◽  
Excessive Load

The efficiency of regenerative heat exchangers with heat storage nozzles made of rolled corrugated tapes depends on the type of their corrugation profile. The most effective form is a triangular one with sharp peaks and troughs. It is technically advisable to get corrugations of a given shape by rolling between two rollers. Determining the required contact load and forces is one of the main tasks when rolling corrugated belts. Insufficient load leads to incomplete formation of the profile, and excessive load leads to warping of the belt. The article presents the results of an experimental study aimed at determining the required load when rolling a corrugated heat exchanger belt for wind tunnels. Experiments and force measurements are carried out on a standard milling machine with a spring dynamometer. The results of the experiment are applied to stainless steel strips with a thickness of 0,3 to 0,4 mm and triangular fluting

Review of Computer Simulations of Regenerative Heat Exchangers

1978 ◽  
Vol 11 (8) ◽  
pp. 309-312
Author(s):  
A. J. Willmott
Keyword(s):  
Heat Exchanger ◽  
Recent Work ◽  
Computer Simulations ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Design Criteria ◽  
Regenerative Heat ◽  
Regenerative Heat Exchanger ◽  
Fuel Savings

Early models of the stationary performance of the regenerative heat exchanger are discussed together with more recent work in which the behaviour under chronologically varying operating conditions is simulated. The need is presented for better control facilities and possibly new design criteria if fuel savings in regenerative heat exchanger non-stationary operations are to be effected.

scholarly journals Comparing ways of calculation efficiency of regenerative heat exchanger

2021 ◽  
Vol 5 (3) ◽  
pp. 39-44
Author(s):  
A. A. Serov ◽  
◽  
A. V. Tsygankov ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Computational Methods ◽  
Heat Balance ◽  
Heat Exchangers ◽  
Computational Study ◽  
Ventilation System ◽  
Cfd Model ◽  
Regenerative Heat ◽  
Air Ventilation

This article contains information on various methods for calculating the efficiency of regenerative heat exchangers in an air ventilation system. The equations of heat balance and heat transfer are described. The results obtained on the CFD model are compared with the results obtained by various mathematical calculations. The obtained results of the computational study can give an assessment of the accuracy of computational methods to obtain the value of the efficiency of regenerative heat exchangers.

Sign in / Sign up

Export Citation Format

Share Document