Design and Analysis of Thermoacoustic Refrigerators Using Air as Working Substance

2019 ◽  
Vol 27 (01) ◽  
pp. 1950008 ◽  
Author(s):  
B. G. Prashantha ◽  
S. Seetharamu ◽  
G. S. V. L. Narasimham ◽  
M. R. Praveen Kumar
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Low Cost ◽  
Design Strategies ◽  
Software Simulation ◽  
Design And Optimization ◽  
Theoretical Design ◽  
Resonator Design ◽  
Simulation Results ◽  
Thermoacoustic Refrigerators

In this paper, the design of 50 W thermoacoustic refrigerators operating with air as working substance at 10 bar pressure and 3% drive ratio for a temperature difference of 28 K is described. The design strategies discussed in this paper help in design and development of low cost thermoacoustic coolers compared to helium as the working substance. The design and optimization of spiral stack and heat exchangers, and the promising 0.2[Formula: see text] and 0.15[Formula: see text] resonator design with taper and divergent section with hemispherical end are discussed. The surface area, volume, length and power density of the hemispherical end design with air as working substance is found better compared to the published 10 and 50 W coolers using helium as the working substance. The theoretical design results are validated using DeltaEC software simulation results. The DeltaEC predicts 51.4% improvement in COP (1.273) at the cold heat exchanger temperature of [Formula: see text]C with air as working substance for the 50[Formula: see text]W 0.15[Formula: see text]TDH resonator design compared to the published 50[Formula: see text]W 0.25[Formula: see text]TDH resonator design with helium as working substance.

Geometrical optimization of bare tube heat exchangers for process industries

2005 ◽  
Vol 219 (2) ◽  
pp. 139-147
Author(s):  
T. Q. Ma ◽  
K. T. Ooi ◽  
T. N. Wong
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Optimization Design ◽  
Design Method ◽  
Outer Diameter ◽  
Process Industries ◽  
Performance Improvements ◽  
Geometrical Optimization ◽  
Simulation Results ◽  
Bare Tube

This paper presents simulation results on the geometrical optimization design of bare tube heat exchangers. By linking a mathematical model with an optimization alogorithm, it is possible to predict which combination of five geometrical variables would produce a given coil capacity of a heat exchanger, the minimum core volume size operating at the minimum pressure drop. A constrained multivariable direct search technique is used in which the five geometrical variables and a mixture of five explicit and implicit constraints are accommodated. Using this design method, three typical sizes of bare tube optimization cases have been studied. The simulation results predict significant performance improvements for heat exchanger design. The range of tube outer diameter in this optimization study is from 4.9 to 9.0 mm.

Oxygen Liquefier Using a Mixed Gas Refrigeration Cycle

2003 ◽  
Author(s):  
Vijayaraghavan Chakravarthy ◽  
Joe Weber ◽  
Abdul-Aziz Rashad ◽  
Arun Acharya ◽  
Dante Bonaquist
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Low Cost ◽  
Rankine Cycle ◽  
Small Scale ◽  
Refrigeration Cycle ◽  
Mixed Gas ◽  
Unit Power ◽  
Design Selection ◽  
Pressure Swing

This paper presents the design, selection of equipment, testing, and analysis of a 2 TPD (76 kg/hr) prototype oxygen liquefier that employs a mixed gas refrigeration cycle. Small scale oxygen plants (30–60 TPD) based on VPSA systems (Vapor Pressure Swing Adsorption) periodically require liquid back-up to provide uninterrupted supply of O2 gas to customers during planned plant maintenance. Supply of liquid for back-up, especially to customers in remote locations, is expensive and difficult. Economically designed MGR liquefiers will fulfill this market need. The 2 TPD prototype O2 liquefier is based on the dual loop MGR Rankine cycle (see Figure 1). The forecooler loop provides refrigeration at the warm end (233K). R507 is used as a refrigerant for the forecooler in the warm end loop. The main refrigeration loop uses a mixture of R218, R14 and N2. The main advantage of separating the refrigerants into two different loops is to avoid freezing of high boiling point refrigerants at liquid O2 temperatures in the main refrigeration loop. The process and mixture composition were optimized using the HYSYS process simulation package. Very useful insights were gained in terms of reducing the irreversibilities in the heat exchanger. Low cost innovative designs were adopted for the heat exchangers. For example: (1) plate-and-frame heat exchangers were successfully used for multiple gas streams, (ii) a spirally wound coiled heat exchanger was used to liquefy oxygen. Similarly, the compressors used in the forecooler and main cycle were low cost, off-the-shelf items used in conventional refrigeration systems. The liquefier unit was initially demonstrated and a liquid making capacity of 1.5 TPD at a unit power of 44 kW/TPD was achieved. Subsequent modifications to the heat exchangers resulted in meeting the design expectations at a unit power of 37 kW/TPD.

scholarly journals Study on the Forming Process and Deformation Behavior of Inner Ring in the Wheel Hub Bearing Based on Riveting Assembly

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3785
Author(s):  
Wei Xiong ◽  
You Wang ◽  
Xiao-Ping Li ◽  
Song Mei ◽  
Zhu-Xin Tian
Keyword(s):  
Deformation Behavior ◽  
High Efficiency ◽  
Low Cost ◽  
Clamping Force ◽  
Forming Process ◽  
Design And Optimization ◽  
Bearing Clearance ◽  
Riveting Process ◽  
Research Findings ◽  
Simulation Results

The orbital riveting process has been successively adopted in the assembly of wheel hub bearing, due to its special merits of high efficiency, low cost, and so on. The forming process and deformation behavior of the inner ring have significant influence on the axial clamping force and bearing clearance, however, which haven’t been addressed yet. In this study, a numerical simulation platform for the assembly of the hub bearing is established by the joint use of the static implicit and dynamic explicit algorithms. Based on the platform, the deformation process and deformation behavior of the inner ring are investigated, along with the interference assembly and riveting assembly on the loading process of the inner ring. Finally, relevant experimental verifications are carried out to consolidate the simulation results. The research findings could be used to guide the design and optimization of the axial clamping force and bearing clearance.

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.

scholarly journals Heat Transfer Enhancement by Using Different Types of Inserts

2014 ◽  
Vol 6 ◽  
pp. 250354 ◽  
Author(s):  
S. Tabatabaeikia ◽  
H. A. Mohammed ◽  
N. Nik-Ghazali ◽  
B. Shahizare
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Heat Exchangers ◽  
Low Cost ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Thermal Systems ◽  
Twisted Tapes ◽  
High Efficient

Heat transfer enhancement has been always a significantly interesting topic in order to develop high efficient, low cost, light weight, and small heat exchangers. The energy cost and environmental issue are also encouraging researchers to achieve better performance than the existing designs. Two of the most effective ways to achieve higher heat transfer rate in heat exchangers are using different kinds of inserts and modifying the heat exchanger tubes. There are different kinds of inserts employed in the heat exchanger tubes such as helical/twisted tapes, coiled wires, ribs/fins/baffles, and winglets. This paper presents an overview about the early studies on the improvement of the performance of thermal systems by using different kinds of inserts. Louvered strip insert had better function in backward flow compared to forward one. Modifying the shape of twisted tapes led to a higher efficiency in most of the cases excpet for perforated twisted tape and notched twisted tape. Combination of various inserts and tube with artificial roughness provided promising results. In case of using various propeller types, heat transfer enhancement was dependent on higher number of blades and blade angle and lower pitch ratio.

scholarly journals Investigation of а stress-strained state of a screw-shape tubes of heat exchangers

2020 ◽  
pp. 13-23
Author(s):  
Serhii Pyskunov ◽  
Serhii Trubachev ◽  
Oleksandr Baranyuk
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Strain State ◽  
Air Flow ◽  
Strained State ◽  
Test Task ◽  
Geometric Characteristics ◽  
Simulation Results ◽  
Brass Screw

Based on the results of the study of the parameters of the air flow inside of the brass screw-shape tube of the heat exchanger, the determination of their optimal geometric characteristics and further modeling of the stress-strain state was performed. Verification of simulation results is carried out on the basis of comparison with the test task.

scholarly journals A Review on Design and optimization of shell and tube heat exchanger by varying parameters

2020 ◽  
Vol 6 (6) ◽  
Author(s):  
Shiv Kumar ◽  
Dharamveer Singh
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Fluid Dynamic ◽  
Exchange Process ◽  
Cost Savings ◽  
Thermal Control ◽  
Tube Heat Exchanger ◽  
Design And Optimization ◽  
Compact Heat Exchangers ◽  
Computation Fluid Dynamic

In recent years, thermal control systems performance has improved in numerous ways due to developments in control theory and information technology. Efforts have been made to produce more efficient heat exchangers by employing various methods of heat transfer enhancement.  An increase in heat exchanger performance can lead to a more economical design of heat exchanger which can help to make energy, material & cost savings related to a heat exchange process. Compact heat exchangers (CHEs) technologies are expected to be one of the solutions for the new generation heat exchanger.  In this paper are presented of the compact heat exchanger, Plate-fin heat exchanger, and Printed Circuit Heat Exchanger. And computation fluid dynamic is used which offers an alternative to the quick and inexpensive solution for the design and optimization of compact heat exchangers.

scholarly journals Research of variable characteristics of heat exchange equipment

2019 ◽  
Vol 114 ◽  
pp. 07001
Author(s):  
Tatyana Rafalskaya ◽  
Valery Rudyak
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Variable Parameter ◽  
Simulation Method ◽  
Operating Modes ◽  
Mode Of Operation ◽  
Heat Exchange Equipment ◽  
Large Systems ◽  
Simulation Results

Heat exchangers used in various industries, most often work in conditions of variable flows and temperatures. At the same time, the existing theories of calculation of heat exchanger modes are based on the use of constant dimensionless parameters in any mode of operation. The purpose of this work is to obtain dependencies to determine the effect of coolant temperatures on the variable parameter of the heat exchanger. Using the simulation method, dependencies were found that describe the change in the heat exchanger parameter which made it possible to obtain a general formula for the change in the heat exchanger parameter at varying coolant temperatures. To test the applicability of the existing relations describing the change in the heat exchanger parameter and the formula obtained, a large number of heat exchangers were calculated in variable operating modes. Comparison with the simulation results showed that the ratios of the known theories of heat exchangers do not work in all modes and their application can lead to significant errors. A formula has been obtained allows one to find the effect of coolant temperatures on the variable parameter of the heat exchanger. The formula can be used to predict the modes of large systems.

Genetic Algorithm Based Design and Optimization of an Outer-Fins and Inner-Fins Tube Heat Exchanger

2007 ◽  
Author(s):  
G. N. Xie ◽  
M. Zeng ◽  
Q. W. Wang
Keyword(s):  
Heat Transfer ◽  
Genetic Algorithm ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Annual Cost ◽  
Total Annual Cost ◽  
Geometrical Parameters ◽  
Tube Heat Exchanger ◽  
Design And Optimization ◽  
Extended Surfaces

One of passive enhancement techniques, Extended Surfaces, are commonly employed in many heat exchangers to enlarge the heat transfer area on gases side because of the low heat transfer coefficients, which may be 10 to 100 times smaller than those of liquids side. The use of extended surfaces (or referred to as finned surfaces) will reduce the thermal resistance of gases side. Enhanced heat transfer coefficient will be achieved by using the basic surface geometries: plate-fin and tube-fin. With respect to the tube-fin type heat exchanger, fins may be employed outside tubes (herein called outer-fins) to enhance the heat transfer of shell-side, and alternatively fins may be also employed inside tubes (herein called inner-fins) to increase the intensity of heat transfer of tube-side. The desire to accomplish the gas-to-gas heat exchange through the tubular heat exchangers will lead to develop heat transfer enhancement techniques for outside and inside tubes. Therefore based on integration with such two mechanisms, namely, outer-fins and inner-fins of enhancement heat transfer techniques, a kind of outer-fins and inner-fins tube heat exchanger has been preliminary proposed (ASME-IGTI, Paper No.2006-90260 [20]). Such heat exchanger is potentially used in gas-to-gas heat exchangers, especially used for highpressure operating conditions, where the plate-fin heat exchangers might not be applicable. In general, the design task is a complex trial-and-error process and there is always the possibility that the design results such as geometrical parameters are not the optimum. Therefore, the motivation of this paper is to conduct optimum designs of such heat exchanger (hereafter called Outer-Fins and Inner-Fins tube Heat Exchanger, OFIF HE). A computational intelligent technique, Genetic Algorithm (GA) is applied to search and optimize geometrical parameters of the OFIF HE. The minimum total volume or minimum total annual cost of such OFIF HE is taken as an objective function in the GA respectively. The results show that the optimized OFIF HE provides lower total volume or lower total annual cost than those presented in previous work. The method is universal and may be used for design and optimization of OFIF HEs under different specified duties and design objectives.

scholarly journals Numerical Study of Compact Plate-Fin Heat Exchanger for Rotary-Vane Gas Refrigeration Machine

2017 ◽  
Vol 53 (2) ◽  
Author(s):  
V. V. Trandafilov ◽  
M. G. Khmelniuk
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Development Research ◽  
Aspen Hysys ◽  
Simulation Results ◽  
Refrigeration Machine

Plate-fin heat exchangers are widely used in refrigeration technique. They are popular because of their compactness and excellent heat transfer performance. Here we present a numerical model for the development, research and optimization of a plate-fin heat exchanger for a rotary-vane gas refrigeration machine. The method of analysis by graphic method of plate - fin heat exchanger is proposed. The model describes the effects of secondary parameters such as axial thermal conductivity through a metal matrix of the heat exchanger. The influence of geometric parameters and heat transfer coefficient is studied. Graphs of dependences of length, efficiency of a fin and pressure drop in a heat exchanger on the thickness of the fin and the number of fins per meter are obtained. To analyze the results of numerical simulation, the heat exchanger was designed in the Aspen HYSYS program. The simulation results show that the total deviation from the proposed numerical model is not more than 15%. 

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