Modeling of ethanol dehydration by diffusion distillation in consideration of the sensible heat transfer

1996 ◽  
Vol 13 (3) ◽  
pp. 275-281 ◽  
Author(s):  
Seong Cheol Kim ◽  
Dong Woo Lee ◽  
Won Hi Hong
Keyword(s):  
Heat Transfer ◽  
Sensible Heat ◽  
Ethanol Dehydration

Thermal Modeling of Unlooped and Looped Pulsating Heat Pipes

2001 ◽  
Vol 123 (6) ◽  
pp. 1159-1172 ◽  
Author(s):  
Mohammad B. Shafii ◽  
Amir Faghri ◽  
Yuwen Zhang
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Heat Pipes ◽  
Analytical Models ◽  
Charge Ratio ◽  
Sensible Heat ◽  
Governing Equations ◽  
Heating Wall ◽  
Heat Mode ◽  
Explicit Finite Difference

Analytical models for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs are presented in this study. The governing equations are solved using an explicit finite difference scheme to predict the behavior of vapor plugs and liquid slugs. The results show that the effect of gravity on the performance of top heat mode unlooped PHP is insignificant. The effects of diameter, charge ratio, and heating wall temperature on the performance of looped and unlooped PHPs are also investigated. The results also show that heat transfer in both looped and unlooped PHPs is due mainly to the exchange of sensible heat.

Solid Media Thermal Storage Development and Analysis of Modular Storage Operation Concepts for Parabolic Trough Power Plants

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Doerte Laing ◽  
Wolf-Dieter Steinmann ◽  
Michael Fiß ◽  
Rainer Tamme ◽  
Thomas Brand ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Heat Storage ◽  
Storage Systems ◽  
Storage System ◽  
Sensible Heat ◽  
Economic Optimization ◽  
Parabolic Trough ◽  
Solid Media ◽  
Exergetic Analysis

Cost-effective integrated storage systems are important components for the accelerated market penetration of solarthermal power plants. Besides extended utilization of the power block, the main benefits of storage systems are improved efficiency of components, and facilitated integration into the electrical grids. For parabolic trough power plants using synthetic oil as the heat transfer medium, the application of solid media sensible heat storage is an attractive option in terms of investment and maintenance costs. For commercial oil trough technology, a solid media sensible heat storage system was developed and tested. One focus of the project was the cost reduction of the heat exchanger; the second focus lies in the energetic and exergetic analysis of modular storage operation concepts, including a cost assessment of these concepts. The results show that technically there are various interesting ways to improve storage performance. However, these efforts do not improve the economical aspect. Therefore, the tube register with straight parallel tubes without additional structures to enhance heat transfer has been identified as the best option concerning manufacturing aspects and investment costs. The results of the energetic and exergetic analysis of modular storage integration and operation concepts show a significant potential for economic optimization. An increase of more than 100% in storage capacity or a reduction of more than a factor of 2 in storage size and therefore investment cost for the storage system was calculated. A complete economical analysis, including the additional costs for this concept on the solar field piping and control, still has to be performed.

scholarly journals Energy Recovery from an Industrial Clothes Dryer Using a Condensing Heat Exchanger

2021 ◽  
Author(s):  
Yousuf Farooq
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Exchanger ◽  
Heat Recovery ◽  
Cold Water ◽  
Waste Heat ◽  
Interface Temperature ◽  
Sensible Heat ◽  
Clothes Dryer ◽  
Condensing Heat Exchanger

The aim of this project was to design a condensing heat exchanger to recover waste heat from an industrial clothes dryer. Industrial cloth dryers are inefficient in their use of energy because almost all of the energy input in the dryer is wasted in the atmosphere, and thus there is great potential for heat recovery. This energy can be used to preheat the incoming cold water, and the conventional heater can then heat the water to a final temperature. The warm moist air from the dryer carries both sensible and latent heat, and in order to design this heat recovery condensing heat exchanger, the heat transfer by both mass and sensible heat has to be accounted for. The basis of this heat and mass transfer problem was the energy balance at the interface, and separate models for the calculation of latent and sensible heat transfer were used. The mass transfer coefficients were obtained from an analogy with heat transfer, and the unknown interface temperature was solved for iteratively. The data for this design was collected from a 20 kW dryer, and the heat recovery from that dryer was observed to be about 17.3%. This heat recovery condensing heat exchanger efficiency can be enhanced by the addition of more coils to the heat exchanger. An improvement in the overall results can be expected if a practical study is done on the condensation heat exchanger for an industrial cloth dryer.

Analysis on unsteady heat transfer and fluid flow through sensible heat storage system

2021 ◽  
Author(s):  
Sasikumar C ◽  
Sundaresan R ◽  
Rajaganapthy C ◽  
Nagaraj M ◽  
Radha Krishnan Beemaraj
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Storage ◽  
Storage System ◽  
Sensible Heat ◽  
Unsteady Heat Transfer ◽  
Flow Through

Diffusion Layer Theory for Turbulent Vapor Condensation With Noncondensable Gases

1993 ◽  
Vol 115 (4) ◽  
pp. 998-1003 ◽  
Author(s):  
P. F. Peterson ◽  
V. E. Schrock ◽  
T. Kageyama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mass Transfer ◽  
Vapor Condensation ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Noncondensable Gas ◽  
Noncondensable Gases ◽  
Vertical Tubes

In turbulent condensation with noncondensable gas, a thin noncondensable layer accumulates and generates a diffusional resistance to condensation and sensible heat transfer. By expressing the driving potential for mass transfer as a difference in saturation temperatures and using appropriate thermodynamic relationships, here an effective “condensation” thermal conductivity is derived. With this formulation, experimental results for vertical tubes and plates demonstrate that condensation obeys the heat and mass transfer analogy, when condensation and sensible heat transfer are considered simultaneously. The sum of the condensation and sensible heat transfer coefficients becomes infinite at small gas concentrations, and approaches the sensible heat transfer coefficient at large concentrations. The “condensation” thermal conductivity is easily applied to engineering analysis, and the theory further demonstrates that condensation on large vertical surfaces is independent of the surface height.

scholarly journals A Heat-Balance Study on Sørbreen, Jan Mayen

1965 ◽  
Vol 5 (42) ◽  
pp. 793-803
Author(s):  
P. C. Dibben
Keyword(s):  
Heat Transfer ◽  
Heat Balance ◽  
Summer Rainfall ◽  
Weather Conditions ◽  
Meteorological Station ◽  
Sensible Heat ◽  
Balance Study ◽  
Statistical Comparison ◽  
Air Temperatures ◽  
Frontal Activity

AbstractThe techniques and results of a heat-balance programme on Sørbreen, Jan Mayen, are presented and discussed. Estimates of 24 hr. heat-transfer totals under frontal and non-frontal weather conditions are then made. Transfer is found to be higher during frontal conditions, due to an increase in latent and to a lesser extent sensible heat transfer. Consideration of upper air temperatures and humidities suggests this higher transfer is experienced by the glacier as a whole. It is then proposed that summer rainfall totals will provide an index of frontal activity which may be used to indicate relative ablation from one summer to another. A statistical comparison of ablation measured on the glacier and rainfall recorded at the Jan Mayen meteorological station supports this suggestion.

Unsteady CHT analysis of a solid state, sensible heat storage for PHES system

2019 ◽  
Vol 30 (6) ◽  
pp. 3199-3209 ◽  
Author(s):  
Bartosz Ziegler ◽  
Jędrzej Mosiężny ◽  
Paweł Czyżewski
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Solid State ◽  
Conjugate Heat Transfer ◽  
Heat Storage ◽  
Sensible Heat ◽  
System Efficiency ◽  
Exergetic Efficiency ◽  
Key Factors ◽  
Content Type

Purpose The aim of this study is to identify key factors limiting efficiency of pumped heat energy storage systems and determine some general features of transient behavior of solid state, sensible heat storages. Moreover, it aimed at establishing a feasible approach to transient conjugate heat transfer (CHT) analyses for such applications. Design/methodology/approach A zero-dimensional analytical model is used to determine the system efficiency sensitivity to efficiency of its components. Analysis of argon gas flow in an exemplary configuration of layered bed thermal energy storage is presented. The analysis incorporates a unsteady reynolds averaged navier stokes model with conjugate heat transfer between gas and solid storage core. Findings It is established that exergetic efficiency of the heat storage is one of the key factors for the system’s overall performance. Three full cycles of storage charging and discharging having 17 h physical time in total are simulated, with calculation of exergetic efficiency for each of the cycles. From standpoint of the system efficiency, it is concluded that the presented heat storage kind has limited exergetic efficiency because of severe temperature drop at the solid–fluid interface in comparison to granular kind of heat storage devices. From the methodological standpoint, it is concluded that calculating the exergetic efficiency of the heat storage by direct computational fluid dynamics (CFD) analysis requires significant amount of walltime and computational resources. Originality/value The paper presents unconventional approach to using standard CFD tools by exploiting numerical diffusion to numerically suppress high-frequency solution oscillations. This strategy grants that the analysis, otherwise requiring impractically long computation walltime, is completed within a practical time.

Evaporative Heat Transfer From Ten-Micron Micro-Channels

2005 ◽  
Author(s):  
T. A. Quy ◽  
D. A. Carpenter ◽  
C. D. Richards ◽  
D. F. Bahr ◽  
R. F. Richards
Keyword(s):  
Heat Transfer ◽  
Electrical Power ◽  
Ccd Camera ◽  
Working Fluid ◽  
Sensible Heat ◽  
Silicon Membrane ◽  
Long Distance ◽  
Liquid Front ◽  
Micro Channels ◽  
Evaporative Heat Transfer

Evaporative heat transfer from ten-micron square open-top micro-channels is investigated experimentally. The channels are fabricated by spinning ten microns of SU-8 on a two micron thick silicon membrane and using a photolithography process to create micro channels in radial and annular patterns. The working fluid, FC77, is pumped by capillary forces into the channels from a reservoir at the edge of the silicon membrane. Electrical power is dissipated in a thin-film heater in the center of the membrane. The liquid front of working fluid in the channels is visualized with a long-distance microscope and CCD camera. Sensible heat conducted radially out of the membrane is measured with two concentric annular PRT’s. The mass of working fluid evaporated from the micro-channels is determined gravimetrically. A global energy balance including latent and sensible heat transfer out of the system is then tabulated. The study shows that only five to ten percent of the power going into the membrane is carried away by evaporation while the remaining ninety to ninety-five percent of the power is conducted out along the membrane.

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