scholarly journals Concurrent studies of enhanced heat transfer and materials for ocean thermal heat exchangers. Semi-annual progress report, March 1--August 31, 1978. [OSCAR code; OTEC Steady-state and Control System Analysis Routines]

1978 ◽  
Author(s):  
R.R. Rothfus ◽  
A.W. Westerberg ◽  
S. Yao ◽  
N.H. Chao ◽  
S. Kuru
Keyword(s):  
Heat Transfer ◽  
Control System ◽  
Steady State ◽  
Heat Exchangers ◽  
System Analysis ◽  
Progress Report ◽  
Enhanced Heat Transfer ◽  
And Control ◽  
Annual Progress Report

scholarly journals Diamond-Shaped Extended Fins for Heat Transfer Enhancement in a Double-Pipe Heat Exchanger: An Innovative Design

2021 ◽  
Vol 11 (13) ◽  
pp. 5954
Author(s):  
Muhammad Ishaq ◽  
Amjad Ali ◽  
Muhammad Amjad ◽  
Khalid Saifullah Syed ◽  
Zafar Iqbal
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Exchangers ◽  
Adaptive Finite Element Method ◽  
Transfer Enhancement ◽  
Enhanced Heat Transfer ◽  
Frictional Loss ◽  
Special Cases ◽  
Double Pipe ◽  
Pipe Heat

Heat transfer enhancement in heat exchangers results in thermal efficiency and energy saving. In double-pipe heat exchangers (DPHEs), extended or augmented fins in the annulus of the two concentric pipes, i.e., at the outer surface of the inner pipe, are used to extend the surface of contact for enhancing heat transfer. In this article, an innovative diamond-shaped design of extended fins is proposed for DPHEs. This type of fin is considered for the first time in the design of DPHEs. The triangular-shaped and rectangular-shaped fin designs of DPHE, available in the literature, can be recovered as special cases of the proposed design. An h-adaptive finite element method is employed for the solution of the governing equations. The results are computed for various performance measures against the emerging parameters. The results dictate that the optimal configurations of the diamond-shaped fins in the DPHE for an enhanced heat transfer are recommended as follows: If around 4–6, 8–12, or 16–32 fins are to be placed in the DPHE, then the height of the fins should be 20%, 80%, or 100%, respectively, of the annulus width. If frictional loss of heat is also to be considered, then for fin-heights of 20–80% and 100% of the annulus width, the placement of 4 and 8 diamond-shaped fins, respectively, is recommended for an enhanced heat transfer. These recommendations are for the radii ratio (i.e., the ratio of the inner pipe radius to that of the outer pipe) of 0.25. The recommendations are be modified if the radii ratio is altered.

Developments in Enhanced Heat Transfer Technology From a Petroleum Industry Perspective in 2012

2012 ◽  
Author(s):  
Matthew P. Rudy ◽  
Thomas M. Rudy ◽  
Himanshu M. Joshi ◽  
Amar S. Wanni
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Petroleum Industry ◽  
Current Paper ◽  
Enhanced Heat Transfer ◽  
The Past

Within the past 30 years, many Enhanced Heat Transfer (EHT) technologies have become available in a number of forms for application in heat exchangers. These technologies are used in various industries to widely different extents. In 1999, H. Joshi, T. Rudy, and A. Wanni, former Ph.D. students of Dr. Ralph L. Webb and specialists in the application of EHTs in the Petroleum Industry prepared a paper for the Journal of Enhanced Heat Transfer that reviewed the extent of use of EHT Technologies in the Petroleum Industry [1]. The current paper reviews how the application of EHT in the Petroleum Industry has changed in the last 14 years.

scholarly journals VILNIUS ADVANCED-SURFACE MOVEMENT GUIDANCE AND CONTROL SYSTEM (A-SMGCS) SAFETY OBJECTIVES / VILNIAUS AERODROMO AUTOMATIZUOTOS ANTŽEMINIO EISMO STEBĖJIMO IR KONTROLĖS SISTEMOS SAUGOS TIKSLŲ ANALIZĖ

Aviation ◽  
2012 ◽  
Vol 16 (4) ◽  
pp. 130-135
Author(s):  
Vaidotas Kondroška ◽  
Jonas Stankūnas
Keyword(s):  
Control System ◽  
System Analysis ◽  
Flight Safety ◽  
Frequency Of Occurrence ◽  
Surface Movement ◽  
Safety Requirements ◽  
Methods Of Determination ◽  
Guidance And Control ◽  
System A ◽  
And Control

This work reviews the innovative and progressive methods of determination and analysis of safety objectives using Vilnius A-SMGCS example. The aim of the analysis is to determine how failures in this system could affect flight safety in Vilnius aerodrome. Identified safety objectives will limit the frequency of occurrence of hazards enough for the associated risk to be acceptable, and will ensure that appropriate mitigation means are reflected subsequently as Safety Requirements for the system. Analysis reflects aspects of A-SMGCS Safety objectives, which should be taken into consideration. Santrauka Darbe apžvelgiami progresyvūs saugos tikslų analizės metodai pagal Vilniaus aerodromo automatizuotos antžeminio eismo stebėjimo ir kontrolės sistemos veiklos pavyzdį. Analizuojama, kaip šios sistemos sutrikimai gali paveikti skrydžių saugą Vilniaus aerodrome. Remiantis galimų pavojų skrydžių saugai analize, tyrime nustatyti saugos tikslai, pagal kuriuos vėliau bus numatomos riziką mažinančios priemonės (galimų pavojų neutralizavimui ar kylančios rizikos sumažinimui iki priimtino lygio). Straipsnyje pateikiami veiksniai, kuriuos reikėtų įvertinti nustatant aerodromo automatizuotos antžeminio eismo stebėjimo ir kontrolės sistemos saugos tikslus.

scholarly journals Performance and Exergy Transfer Analysis of Heat Exchangers with Graphene Nanofluids in Seawater Source Marine Heat Pump System

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1762 ◽  
Author(s):  
Zhe Wang ◽  
Fenghui Han ◽  
Yulong Ji ◽  
Wenhua Li
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Transfer Model ◽  
Enhanced Heat Transfer ◽  
Pump System ◽  
Heat Pump System ◽  
Tube Heat Exchanger ◽  
Exergy Transfer

A marine seawater source heat pump is based on the relatively stable temperature of seawater, and uses it as the system’s cold and heat source to provide the ship with the necessary cold and heat energy. This technology is one of the important solutions to reduce ship energy consumption. Therefore, in this paper, the heat exchanger in the CO2 heat pump system with graphene nano-fluid refrigerant is experimentally studied, and the influence of related factors on its heat transfer enhancement performance is analyzed. First, the paper describes the transformation of the heat pump system experimental bench, the preparation of six different mass concentrations (0~1 wt.%) of graphene nanofluid and its thermophysical properties. Secondly, this paper defines graphene nanofluids as beneficiary fluids, the heat exchanger gains cold fluid heat exergy increase, and the consumption of hot fluid heat is heat exergy decrease. Based on the heat transfer efficiency and exergy efficiency of the heat exchanger, an exergy transfer model was established for a seawater source of tube heat exchanger. Finally, the article carried out a test of enhanced heat transfer of heat exchangers with different concentrations of graphene nanofluid refrigerants under simulated seawater constant temperature conditions and analyzed the test results using energy and an exergy transfer model. The results show that the enhanced heat transfer effect brought by the low concentration (0~0.1 wt.%) of graphene nanofluid is greater than the effect of its viscosity on the performance and has a good exergy transfer effectiveness. When the concentration of graphene nanofluid is too high, the resistance caused by the increase in viscosity will exceed the enhanced heat transfer gain brought by the nanofluid, which results in a significant decrease in the exergy transfer effectiveness.

scholarly journals Corrosion and corrosion prevention in heat exchangers

2019 ◽  
Vol 37 (2) ◽  
pp. 131-155 ◽  
Author(s):  
Willem Faes ◽  
Steven Lecompte ◽  
Zaaquib Yunus Ahmed ◽  
Johan Van Bael ◽  
Robbe Salenbien ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Prevention And Control ◽  
Metallic Materials ◽  
Corrosion Prevention ◽  
Design Considerations ◽  
Repair Costs ◽  
Anodic Protection ◽  
Different Types ◽  
And Control

AbstractIn many industries and processes, heat exchangers are of vital importance as they are used to transfer heat from one fluid to another. These fluids can be corrosive to heat exchangers, which are usually made of metallic materials. This paper illustrates that corrosion is an important problem in the operation of heat exchangers in many environments, for which no straightforward answer exists. Corrosion failures of heat exchangers are common, and corrosion often involves high maintenance or repair costs. In this review, an overview is given of what is known on corrosion in heat exchangers. The different types of corrosion encountered in heat exchangers and the susceptible places in the devices are discussed first. This is combined with an overview of failure analyses for each type of corrosion. Next, the effect of heat transfer on corrosion and the influence of corrosion on the thermohydraulic performances are discussed. Finally, the prevention and control of corrosion is tackled. Prevention goes from general design considerations and operation guidelines to the use of cathodic and anodic protection.

Corrective movements following refixation saccades: Type and control system analysis

1972 ◽  
Vol 12 (3) ◽  
pp. 467-475 ◽  
Author(s):  
Ronald B. Weber ◽  
Robert B. Daroff
Keyword(s):  
Control System ◽  
System Analysis ◽  
And Control
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