scholarly journals Optimization of a New Design of Molten Salt-to-CO2 Heat Exchanger Using Exergy Destruction Minimization

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 883
Author(s):  
María José Montes ◽  
José Ignacio Linares ◽  
Rubén Barbero ◽  
Beatriz Yolanda Moratilla
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Molten Salt ◽  
High Heat ◽  
Exergy Destruction ◽  
Solar Thermal Energy ◽  
Heat Exchanger Design ◽  
Central Receiver ◽  
High Heat Transfer ◽  
Supercritical Phase

One of the ways to make cost-competitive electricity, from concentrated solar thermal energy, is increasing the thermoelectric conversion efficiency. To achieve this objective, the most promising scheme is a molten salt central receiver, coupled to a supercritical carbon dioxide cycle. A key element to be developed in this scheme is the molten salt-to-CO2 heat exchanger. This paper presents a heat exchanger design that avoids the molten salt plugging and the mechanical stress due to the high pressure of the CO2, while improving the heat transfer of the supercritical phase, due to its compactness with a high heat transfer area. This design is based on a honeycomb-like configuration, in which a thermal unit consists of a circular channel for the molten salt surrounded by six smaller trapezoidal ducts for the CO2. Further, an optimization based on the exergy destruction minimization has been accomplished, obtained the best working conditions of this heat exchanger: a temperature approach of 50 °C between both streams and a CO2 pressure drop of 2.7 bar.

Study on Condensation Behavior in Two-Phase Flow Through a Microchannel

2008 ◽  
Author(s):  
Genki Takeuchi ◽  
Akiko Fujiwara ◽  
Yutaka Abe ◽  
Yutaka Suzuki
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Capillary Tube ◽  
High Heat ◽  
Flow Patterns ◽  
Rate Condition ◽  
High Heat Transfer

It is requested to develop a small and high performance heat exchanger for small size energy equipments such as fuel cells and CO2 heat pumps, et.al... In author’s previous studies, a high pressure resistant microchannel layers stacked heat exchanger has been developed. The heat exchanger is manufactured by diffusion bond technique. It can be used under high pressure condition larger than 15 MPa. Due to the high pressure resistance, the device can be applied for high flow rate condition with boiling and condensation. The objectives of the present study are to estimate the heat transfer performance of the heat exchanger and to investigate the thermal hydraulic behavior in the microchannel. The flow pattern in a glass capillary tube is observed by fabricating visualization system. As the results, it is measured that the present device attained high heat transfer quantity of approximately 7000 W on steam condensation despite the weight is only 230 g. The measurement results clarified that the device achieves very high heat transfer rate of hundreds times larger than that of the existing heat exchanger. Furthermore, visualization experiment with single glass pipe is conducted to clarify the flow condensation behavior in the microchannel. In the experiment, the microchannel of Pyrex glass is surrounded by the subcooling water. The flow patterns can visualized from the side of the microchannel. Flow patterns observations are conducted for various inlet pressure and temperatures of the subcooling water. It is observed that the continuous flow transition from annular and injection flow to slug-bubble flow in the microchannel. The reason of large heat transfer rate per unit volume is discussed as relating to narrow interval of each microchannels and small thermal resistance.

Decreasing the Fouling of Heat Exchanger Plates Using Air Bubbles

2010 ◽  
Vol 297-301 ◽  
pp. 1199-1204 ◽  
Author(s):  
Seung Moon Baek ◽  
Won Sil Seol ◽  
Ho Saeng Lee ◽  
Jung In Yoon
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Environmental Pollution ◽  
High Heat ◽  
Air Bubbles ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Heat Exchanger Plate ◽  
Removal Equipment ◽  
Exchanger Plate

The heat transfer performance of heat exchanger plate decreases as time goes by. The main reason for this phenomenon is the fouling of the heat exchanger plates. To remove the fouling, we have usually cleaned the plate of heat exchanger using chemicals or polishing brush or cloth with hand after stopping the equipment and disassembling the heat exchanger. However, to clean the plate using these methods, the heat exchanger equipment needs to be stopped and disjointed. In addition, it must be re-jointed after cleaning. Especially, the concern of environmental pollution happens in case of using chemicals. Therefore, we need to develop an automatic fouling removal equipment which can continuously keep high heat transfer efficiency and solve the problem of environmental pollution. So, in this paper, we developed and tested the equipment which can clean the fouling on heat exchanger plates automatically per constant period and interval using air bubbles. The total heat transfer coefficient decreased with a slower tendency when using air bubbles compared to the existing methods. There was 10% higher heat transfer effect air bubbles every 10 minutes for 2 hours to remove the fouling ingredients on the heat transfer surface area concerned to the case without air bubbles after 192 hours.

Enhanced Heat Transfer in Single-Phase Forced Convection in Tubes due to Helical Swirl Generated by Twisted-Tape Inserts

2012 ◽  
Author(s):  
Arthur E. Bergles ◽  
Raj M. Manglik
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Single Phase ◽  
Fluid Motion ◽  
High Heat ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Heat Exchanger Design ◽  
High Heat Transfer

Very high heat transfer enhancement can be achieved in single-phase flows by using twisted-tape inserts in circular tubes. The primary convection mechanism is the generation of helical swirl or secondary fluid motion that is induced by the helical curvature of the tape insert. This promotes cross-stream mixing and sharper wall gradients, which are further aided by the increased flow velocity due to the tube partitioning and blockage along with an effectively longer helical flow length. These phenomena are scaled for both laminar and turbulent flow regimes, and an evaluation of the transition is also given to highlight the damping effects of tape-generated swirl. The nature of swirl and its dimensionless scaling, and concomitant development of predictive correlations for heat transfer coefficients and friction factors are discussed. Finally, a brief discussion of the quantification of heat transfer enhancement by means of twisted tapes is given so as to extend their application in heat exchanger design.

scholarly journals DEVELOPMENT OF A HEAT EXCHANGE DEVICE FOR COOLING RETAIL WATER WITH ATMOSPHERIC AIR

2020 ◽  
Vol 2020 (1) ◽  
pp. 9-10
Author(s):  
Aleksey Bal'chugov ◽  
Borislav Kustov
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
High Heat ◽  
Cooling Towers ◽  
Recycled Water ◽  
Transfer Rates ◽  
Atmospheric Air ◽  
Circulating Water ◽  
High Heat Transfer

A new design of a heat exchanger for cooling circulating water with atmospheric air is proposed. Compared to cooling towers, the new unit eliminates the loss of recycled water and ensures high heat transfer rates

Development of High Heat Transfer Titanium Sheet for Heat Exchanger

2016 ◽  
pp. 1825-1829
Author(s):  
Keitaro Tamura ◽  
Yoshio Itsumi ◽  
Hideto Oyama ◽  
Akio Okamoto ◽  
Hiroshi Arima ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
High Heat ◽  
Titanium Sheet ◽  
High Heat Transfer

scholarly journals NUMERICAL INVESTIGATION OF THERMOHYDRAULIC PERFORMANCE OF TRIPLE CONCENTRIC-TUBE HEAT EXCHANGER WITH LONGITUDINAL FINS

2021 ◽  
Vol 16 (8) ◽  
Author(s):  
Shafquat Hussain
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Crude Oil ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
High Heat ◽  
Diesel Oil ◽  
Engine Oil ◽  
Tube Heat Exchanger ◽  
High Heat Transfer

In this work, a triple concentric-tube heat exchanger (TCTH) with or without the application of longitudinal fins is numerically studied concerning its thermohydraulic performance. The computational fluid dynamics (CFD) program, Ansys FLUENT was used to perform the simulations to study the heat transfer enhancement using three different types of hot fluids, i.e. Crude oil, engine oil, and light diesel oil. The validated numerical model was first employed to investigate the heat transfer performance of unfinned TCTHE. Then, longitudinal fins were modeled and investigated for comparative analyses of the thermohydraulic performances of both constructions. To predict the heat exchanger performance, key parameters such as heat flux and temperature field distribution were evaluated. Results revealed that modifying the heat exchanger with longitudinal fins on the tube surface dramatically improves its heat transfer rate. Therefore, this research is designed to keep in view further exploring the potential of longitudinal fins in obtaining an improved performance from these types of heat exchanger devices. The results showed that the crude oil fluid has high heat transfer rate than the other two fluids light diesel oil and engine oil. With the application of fins on the tubes’ surfaces, a significant heat transfer exchange among the fluids streams is observed.

scholarly journals Study on Testing Methods for the Heat Transfer Performance of Plate Heat Exchangers

2021 ◽  
Vol 245 ◽  
pp. 01048
Author(s):  
Bin Ren ◽  
Xuchen Zhu ◽  
Yannan Du ◽  
Zhe Pu ◽  
Hongliang Lu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
High Heat ◽  
Plate Heat Exchanger ◽  
Transfer Performance ◽  
Plate Heat ◽  
High Heat Transfer ◽  
Wilson Plot

Plate heat exchangers are new-type compact heat exchangers with high heat transfer efficiency widely used in heating, food, medicine, shipbuilding and petrochemical industries. However, only the laboratory testing can accurately obtain the real heat transfer and flow resistance performance of plate heat exchanger. In this paper, the basic principles of modified Wilson plot method and equal velocity method are firstly introduced. Then the testing system including flow chart and testing instruments are discussed. Finally, contrast experiments using the different two methods are conducted. The results showed that for plate heat exchangers with equal channel, the equal velocity method and modified Wilson plot method can both be used to test the convective heat transfer performance of plate heat exchanger. The equal velocity method is recommended because the deformation of plate is relatively smaller.

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