4.11 Beyond the Large LOCA: Current Heat Transfer Aspects of LWR Safety Analysis

1980 ◽  
Author(s):  
S. P. Kalra ◽  
Romney B. Duffey ◽  
M. Merilo ◽  
K. H. Sun ◽  
Yoram Zvirin
Keyword(s):  
Heat Transfer ◽  
Safety Analysis ◽  
Current Heat

Numerical Simulation of Bubble Growth During Nanofluid Flow Boiling in a Microchannel

2014 ◽  
Author(s):  
Arman Khalighi ◽  
Matthew Blomquist ◽  
Abhijit Mukherjee
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Heat Dissipation ◽  
Flow Boiling ◽  
Contact Angles ◽  
Electronic Systems ◽  
Simulation Based ◽  
Fluid Media ◽  
Thermo Physical Properties ◽  
Current Heat

In recent years, heat dissipation in micro-electronic systems has become a significant design limitation for many component manufactures. As electronic devices become smaller, the amount of heat generation per unit area increases significantly. Current heat dissipation systems have implemented forced convection with both air and fluid media. However, nanofluids may present an advantageous and ideal cooling solution. In the present study, a model has been developed to estimate the enhancement of the heat transfer when nanoparticles are added to a base fluid, in a single microchannel. The model assumes a homogeneous nanofluid mixture, with thermo-physical properties based on previous experimental and simulation based data. The effect of nanofluid concentration on the dynamics of the bubble has been simulated. The results show the change in bubble contact angles due to deposition of the nanoparticles has more effect on the wall heat transfer compared to the effect of thermo-physical properties change by using nanofluid.

A Novel Gas-Water Heat Exchanger With Minichannels

2008 ◽  
Author(s):  
Yang Chen ◽  
Per Lundqvist ◽  
Bjo¨rn Palm
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Low Pressure ◽  
Shell Side ◽  
Hot Air ◽  
Drop Flow ◽  
Counter Current ◽  
Good Heat ◽  
Current Heat

In the current study, a novel gas water heat exchanger with minichannels is designed, built and tested. The heat exchanger is mainly composed of a number of concentric ring shaped plates, which are made up of several heat exchanger tubes. The ring shaped plates are arranged in parallel and placed in a shell. The heat exchanger is designed as a counter current heat exchanger with laminar flow on the heat exchanger’s shell-side (gas side) and therefore has a very low pressure drop on the shell side. The heat exchanger was tested with water and hot air on its tube-side and shell-side respectively. All the necessary parameters like inlet and outlet temperatures on tube-side and shell-side as well as the pressure drop, flow rate of fluids, etc. were measured. Different existing correlations were used to calculate the overall heat transfer coefficient and the results were compared with the measured value. The measured results show that the new designed heat exchanger can achieve a good heat transfer performance and also maintain a low pressure drop on shell-side (gas side).

Assessment of Heat Transfer Effectiveness: Application to Shell Bitumen Plant, Takoradi, Ghana

2008 ◽  
Author(s):  
Anthony Simons ◽  
Solomon Nunoo
Keyword(s):  
Heat Transfer ◽  
Heat Losses ◽  
Heat Energy ◽  
Fuel Oil ◽  
High Rate ◽  
Liquefied Petroleum Gas ◽  
Temperature Range ◽  
The Face ◽  
Selection Of ◽  
Current Heat

At Shell Bitumen Plant, Takoradi, Beverley Thermal Fluid Heater (BTFH) generates heat energy to heat thermal fluid (Thermia B) which flows through heat exchanger and then heats bitumen which is to be maintained at temperature range of 140 °C to 160 °C before it is discharged. High rate of heat losses have been observed and in order to maintain the temperature range of bitumen at (140 °C to 160 °C), a lot of heat energy is needed to be generated which means higher fuel consumption for BTFH. Industrial fuel oil is used to fuel the BTFH. This paper assesses the existing insulation system on the plant and seeks to improve on it so as to cut down heat losses. Consequently, the work looked at the estimation of heat losses, selection of materials for heat transfer and lagging purposes. In this wise, the existing laggings were modified by introducing fibreglass between the asbestos and masonry and thus reducing the current heat lost by 78%. Heat from the exhaust gas which would have otherwise, gone wasted, was utilised by redesigning the chimney and this yielded 0.868 kW of heat energy to aid the heating of the bitumen. In the face of rising cost of fuel and taking cognizance of the fact that cheaper natural gas and liquefied petroleum gas could be produced in Ghana, it is recommended that the heater should be fueled by either of these gases.

scholarly journals Assessment of CHF and Post-CHF Heat Transfer Models for High-Pressure Condition

2021 ◽  
Vol 9 ◽  
Author(s):  
Meiqi Song ◽  
Xiaojing Liu
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Literature Review ◽  
Prediction Models ◽  
Safety Analysis ◽  
Pressure Condition ◽  
Predictive Capability ◽  
The World ◽  
Transfer Models

Supercritical heat transfer systems may undergo trans-critical procedures and work at subcritical conditions during startup, shutdown, or some accidents. However, well-validated heat transfer models for the high-pressure condition (P/Pc>0.7) are still missing. In the present work, with exhaustive literature review, extensive experimental databanks of CHF and post-dryout heat transfer under high-pressure condition are established, respectively. Existing prediction models for the high-pressure condition are also summarized from all over the world. Thereby, with the aid of the high-pressure experimental databank, prediction models get evaluated. It has been demonstrated that CHF correlation developed by Song et al. shows good predictive capability. Post-dryout heat transfer could get well predicted by the Song correlation. These recommended prediction models could be implemented to upgrade safety analysis codes for simulation of trans-critical transients.

Poisson Conduction Shape Factors for “Mixed Case” Counter-Current Heat Transfer Applications

2004 ◽  
Author(s):  
Devashish Shrivastava ◽  
Robert B. Roemer
Keyword(s):  
Heat Transfer ◽  
Vessel Wall ◽  
Source Term ◽  
The Other ◽  
Tissue Temperature ◽  
Shape Factors ◽  
Mixed Case ◽  
Boundary Temperature ◽  
Counter Current ◽  
Current Heat

The effects of a source term and geometry on vessel-vessel and vessel-tissue Poisson conduction shape factors (VVPCSFs and VTPCSFs) are studied for uniformly heated, finite, non-insulated tissues for the ‘mixed case’ i.e., when the tissue boundary temperature lies in between the two vessel wall temperatures. In addition, two alternative formulations for the VTPCSFs are compared; while both formulations use the vessel wall temperature, one uses the tissue boundary temperature, and the other the area averaged tissue temperature. Results show that the VVPCSFs are only geometry dependent and do not depend on the applied power or the two vessel wall and tissue boundary temperatures. Conversely, the VTPCSFs are strong functions of these variables.

Design of Condensation Heat Transfer Experiment to Evaluate Scaling Distortion in Small Modular Reactor Safety Analysis

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
Palash K. Bhowmik ◽  
J. P. Schlegel ◽  
V. Kalra ◽  
C. Mills ◽  
S. Usman
Keyword(s):  
Heat Transfer ◽  
Test Data ◽  
Cooling System ◽  
Safety Analysis ◽  
Nuclear Industry ◽  
Condensation Heat Transfer ◽  
Saturated Steam ◽  
Test Facility ◽  
Working Fluid ◽  
Different Diameters

Abstract Designing a novel scaled modular test facility as a part of an experiment for condensation heat transfer (CHT) in small modular reactors (SMRs) is the main focus of this study. This facility will provide data to evaluate models' scalability for predicting heat transfer in the passive containment cooling system (PCCS) of SMR. The nuclear industry recognizes SMRs as future candidates for clean, economic, and safe energy generation. However, licensing requires proper evaluation of the safety systems such as PCCS. The knowledge gap from the literature review showed a lack of high-resolution experimental data for scaling of PCCS and validation of computational fluid dynamics tools. In addition, the presently available test data are inconsistent due to unscaled geometric and varying physics conditions. These inconsistencies lead to inadequate test data benchmarking. To fill this research gap, this study developed three scaled (different diameters) condensing test sections with annular cooling for scale testing and analysis. This facility considered saturated steam as the working fluid with noncondensable gases like nitrogen and helium in different mass fractions. This facility also used a precooler unit for inlet steam conditioning and a postcooler unit for condensate cooling. The high fidelity sensors, instruments, and data acquisition systems are installed and calibrated. Finally, facility safety analysis and shakedown tests are performed.

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