Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

Flow Boiling in Horizontal Tubes: Part 3—Development of a New Heat Transfer Model Based on Flow Pattern

1998 ◽  
Vol 120 (1) ◽  
pp. 156-165 ◽  
Author(s):  
N. Kattan ◽  
J. R. Thome ◽  
D. Favrat
Keyword(s):  
Heat Transfer ◽  
Annular Flow ◽  
Flow Boiling ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Two Phase ◽  
Horizontal Tubes ◽  
High Vapor ◽  
Coefficient Versus ◽  
The Heat Transfer Coefficient

A new heat transfer model for intube flow boiling in horizontal plain tubes is proposed that incorporates the effects of local two-phase flow patterns, flow stratification, and partial dryout in annular flow. Significantly, the local peak in the heat transfer coefficient versus vapor quality can now be determined from the prediction of the location of onset of partial dryout in annular flow. The new method accurately predicts a large, new database of flow boiling data, and is particularly better than existing methods at high vapor qualities (x > 85 percent) and for stratified types of flows.

Lower Bound Estimate for Droplet Size in Two-Phase Dispersed Flow

1980 ◽  
Vol 102 (3) ◽  
pp. 501-507 ◽  
Author(s):  
C. F. Delale
Keyword(s):  
Heat Transfer ◽  
Lower Bound ◽  
Droplet Diameter ◽  
Transfer Model ◽  
Two Phase ◽  
Dispersed Flow ◽  
One Dimensional ◽  
Droplet Sizes ◽  
Using Data ◽  
Lower Bound Estimate

A theoretical post-dryout heat transfer model is developed based on one-dimensional two-phase dispersed flow and is applied to calculate the wall temperatures in the post-CHF regime. The model is also applied to reason the existence of a lower bound for average droplet diameter in two-phase dispersed flow. Results obtained using data by Bennett, et al. show lower droplet sizes than the experimentally measured values.

A Mechanistic Heat Transfer Model for Vertical Two-Phase Flow

2003 ◽  
Author(s):  
Ryo Manabe ◽  
Qian Wang ◽  
Hong-Quan Zhang ◽  
Cem Sarica ◽  
James P. Brill
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Phase Flow ◽  
Two Phase

Two-phase heat transfer model for multiprobe cryosurgery

2017 ◽  
Vol 113 ◽  
pp. 47-57 ◽  
Author(s):  
Xin Zhang ◽  
S.M. Chapal Hossain ◽  
Gang Zhao ◽  
Beisheng Qiu ◽  
Xiaoming He
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Two Phase ◽  
Two Phase Heat Transfer

scholarly journals DEVELOPMENT AND VALIDATION OF A CONJUGATE HEAT TRANSFER MODEL FOR THE TWO-PHASE CFD CODE NEK-2P

2019 ◽  
Author(s):  
Prasad Vegendla ◽  
Adrian Tentner ◽  
Dillon Shaver ◽  
Aleks Obabko ◽  
Elia Merzari
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Two Phase ◽  
Development And Validation

scholarly journals Optimal selection of two-phase tube-side heat transfer model for small-scale LNG spiral wound heat exchanger

2019 ◽  
Vol 25 (1) ◽  
pp. 47-55
Author(s):  
Chongzheng Sun ◽  
Yuxing Li ◽  
Hui Han ◽  
Jianlu Zhu
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Natural Gas ◽  
Gas Production ◽  
Heat Transfer Model ◽  
Small Scale ◽  
Transfer Model ◽  
Two Phase ◽  
S Model ◽  
Spiral Wound

Small-scale devices of liquefied natural gas (LNG) have been widely applied in the natural gas industries, especially for stranded gas production. As the key equipment of LNG plants, the performance of the spiral wound heat exchanger (SWHE) influences operating costs, reliability and safety of the whole system. In order to obtain the accurate two-phase tube-side heat transfer model for small-scale LNG SWHE and analyze its thermal performance, an experimental device of dual mixed refrigeration (DMR) is constructed. A multi-phase multi- -stream calculation code for SWHE is developed to solve the energy balance equations among tube-side feed gas, tube-side refrigerant and shell-side refrigerant, based on experimental results and thermal property calculation. The results show that the homogeneous flow model can be applied to two-phase tube-side heat transfer calculation of feed gas and Bell and Ghaly?s model and Shah?s model can be both applied to the mixed refrigerant. The relative errors between the results of the experiment and program are all within the range of ?12%.

scholarly journals A Numerical Method for Analysing Heat Conduction in Composites Containing Encapsulated Phase Change Materials

2018 ◽  
Vol 237 ◽  
pp. 02012
Author(s):  
Hui Wang ◽  
Qing-Hua Qin
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Composite System ◽  
Matrix Material ◽  
Heat Transfer Model ◽  
Transient Heat Transfer ◽  
Cement Matrix ◽  
Transfer Model ◽  
Two Phase ◽  
Three Phase

In this study, a three-dimensional transient heat transfer model in a three-phase composite system is established to investigate effects of temperature reduction in a composite system due to the use of encapsulated phase change material (PCM). The entire composite system is composed of cement matrix material, PCM, and hollow metal microspheres (HMSs) which are introduced to accelerate the phase change efficiency of the PCM and to simultaneously hold the liquid phase of the PCM. The present transient heat transfer model is numerically solved via finite element technique for investigating the transient thermal performance of the three-phase composite system. The temperature distribution on the specific area is compared to that in the pure cement material and the two-phase composite system without metal shell for demonstrating the ability of temperature adjustment of the PCM. Finally, effects of the spatial distribution of HMS on the temperature variation in the three-phase composite system is further investigated to provide comprehensive understanding on energy adjustment of this composite system.

A New Thermodynamic and Heat Transfer Model for Nanolubricants and Refrigerant Heat Transfer Processes in Smooth Copper Tubes

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Pratik S. Deokar ◽  
Lorenzo Cremaschi ◽  
Andrea A. M. Bigi
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Single Phase ◽  
Flow Boiling ◽  
Heat Transfer Model ◽  
Forced Flow ◽  
Transfer Model ◽  
Phase Flow ◽  
Two Phase

Abstract In air conditioning systems, lubricating oil leaves the compressor and circulates through the other system components. This lubricant acts as a contaminant affecting heat transfer in heat exchangers. The literature indicated that mixtures of refrigerants and nanolubricants, that is, nanoparticles dispersed in the lubricant oils, have potentials to augment heat transfer exchange effectiveness. However, the nanoparticle mechanisms leading to such heat transfer changes are still unclear and not well included in the models. In this work, an existing single-phase forced flow convective heat transfer model, originally developed for water-based nanofluids, was modified to include the effects of diffusion and mass balance of different shape nanoparticles within the laminar sublayer and turbulent layer of the flow. A new physics-based superposition heat transfer model for saturated two-phase flow boiling of refrigerant and nanolubricants was also developed by integrating the modified forced flow convective heat transfer model and a semi-empirical pool boiling model for nanolubricants. The new model included the several physical effects that influenced heat transfer, such as slip mechanisms at the nanoparticles and base fluid interface and its influence on the laminar sublayer thickness, momentum transfer from the nanoparticles to the growing bubbles, and formation of lubricant excess concentration at the tube surface and its influence on bubble growth and tube wetting. The new model was validated for single-phase convective heat transfer and two-phase flow boiling of refrigerant R410A with two nanolubricants, having nonspherical ZnO nanoparticles and spherical Al2O3 nanoparticles.

Sign in / Sign up

Export Citation Format

Share Document