scholarly journals The Sandia National Laboratories Natural Circulation Cooler

2021 ◽  
Author(s):  
Bobby D. Middleton ◽  
Patrick V. Brady ◽  
Serafina Lawles
Keyword(s):  
Power Plants ◽  
Cooling System ◽  
Natural Circulation ◽  
Two Phase ◽  
Heat Rejection ◽  
Dry Heat ◽  
Current State ◽  
Hybrid Cooling ◽  
Single Temperature ◽  
Zeotropic Mixture

Abstract Sandia National Laboratories (SNL) is developing a cooling technology concept — the Sandia National Laboratories Natural Circulation Cooler (SNLNCC) — that has potential to greatly improve the economic viability of hybrid cooling for power plants. The SNLNCC is a patented technology that holds promise for improved dry heat rejection capabilities when compared to currently available technologies. The cooler itself is a dry heat rejection device, but is conceptualized here as a heat exchanger used in conjunction with a wet cooling tower, creating a hybrid cooling system for a thermoelectric power plant. The SNLNCC seeks to improve on currently available technologies by replacing the two-phase refrigerant currently used with either a supercritical fluid — such as supercritical CO2 (sCO2) — or a zeotropic mixture of refrigerants. In both cases, the heat being rejected by the water to the SNLNCC would be transferred over a range of temperatures, instead of at a single temperature as it is in a thermosyphon. This has the potential to improve the economics of dry heat rejection performance in three ways: decreasing the minimum temperature to which the water can be cooled, increasing the temperature to which air can be heated, and increasing the fraction of the year during which dry cooling is economically viable. This paper describes the experimental basis and the current state of the SNLNCC.

scholarly journals Calculations of the pressure drop in the natural circulation boiler evaporator

2018 ◽  
Vol 240 ◽  
pp. 05009 ◽  
Author(s):  
Slawomir Grądziel ◽  
Karol Majewski
Keyword(s):  
Pressure Drop ◽  
Power Plants ◽  
Graphical Method ◽  
Natural Circulation ◽  
Homogeneous Model ◽  
Phase Slip ◽  
Two Phase Flows ◽  
Two Phase ◽  
Pressure Losses

The paper presents different models used to determine pressure losses in two-phase flows: the homogeneous model, the Lockhart-Martinelli, the Friedel and the Chisholm phase-slip models and the Martinelli-Nelson graphical method. The pressure losses are calculated for the evaporator of an OP-210 boiler with the output of 210×103 kg/h operating in one of the Polish power plants. The results obtained by means of the presented models are compared to each other.

Economic Design of Hybrid Wet-Dry Cooling Systems

2013 ◽  
Author(s):  
R. W. Card
Keyword(s):  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Weather Data ◽  
Net Generation ◽  
Steam Turbines ◽  
Cooling Systems ◽  
Hybrid Cooling ◽  
Seasonal Basis ◽  
Dry Cooling

A hybrid wet-dry cooling system can be designed for a large combined-cycle power plant. A well-designed hybrid cooling system will provide reasonable net generation year-round, while using substantially less water than a conventional wet cooling tower. The optimum design for the hybrid system depends upon climate at the site, the price of power, and the price of water. These factors vary on a seasonal basis. Two hypothetical power plants are modeled, using state-of-the-art steam turbines and hybrid cooling systems. The plants are designed for water-constrained sites incorporating typical weather data, power prices, and water prices. The principles for economic designs of hybrid cooling systems are demonstrated.

Periodic Oscillations in Natural Circulation Boiling System

2017 ◽  
Author(s):  
Xianbing Chen ◽  
Puzhen Gao ◽  
Qiang Wang ◽  
Yinxing Zhang ◽  
Jiawei Liu
Keyword(s):  
Mass Flux ◽  
Nuclear Power ◽  
Power Plants ◽  
Two Phase Flow ◽  
Flow Instability ◽  
Natural Circulation ◽  
Flow Reversal ◽  
Phase Flow ◽  
Two Phase ◽  
Periodic Oscillations

Natural circulation has been widely used in some evolutionary and innovative nuclear power plants. Natural circulation systems are susceptible to flow instabilities which are undesirable in the nuclear power devices. An experimentally investigation of two phase flow instability in up-flow boing channel under natural circulation is presented in this paper. Flow instability with and without flow reversal have been found. A pulse signal of water temperature at the inlet of the test section can be detected when the channel suffers from flow reversal. Single phase and two phase flow alternate in the channel regardless of the occurrence of flow reversal. Periodic oscillations with multiple high-order harmonic waves are confirmed by applying Fast Fourier Transform to the time traces of flow rates. Period of flow instability which is the reciprocal of the frequency with the largest amplitude in the amplitude-frequency plane are obtained. Period of flow oscillation presents a nonlinear change with the increase of mass flux. Period of flow instability increases rapidly with the increase of mass flux and decreases slowly when it reaches the maximum value.

scholarly journals The development of a model for predicting the stability boundaries of natural circulation process

2020 ◽  
Author(s):  
Vyacheslav Andreev ◽  
Ekaterina Orekhova ◽  
Natalya Tarasova ◽  
Julia Perevezentseva
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Natural Circulation ◽  
Reactor Core ◽  
Passive Systems ◽  
Two Phase ◽  
Operating Personnel ◽  
Stability Boundaries ◽  
Operating Limits ◽  
The Stability

The concept of safety for facilities comprising nuclear power plants implies in large the use of passive systems. One of the main passive systems in a nuclear power plant is a system for cooling the reactor core with its action based on gravitational forces. In this regard, the importance of such a physical process as natural circulation is increasing with the development of nuclear power facilities. However, this system has not only advantages but some drawbacks as well. These are the emergence of instability in the two-phase coolant flow, pulsations of thermohydraulic parameters, possible circulation reversal and stagnation. This paper deals with the study of a generalized model of the natural circulation stability. The said model is designed to simplify the design engineering of power equipment. This model will also enable the operating personnel to predict the operating limits of the equipment and remain within the coolant stability bounds. This paper presents a model for predicting the stability boundaries of natural circulation process.

scholarly journals The Development of Models to Predict the Stability of Natural Circulation of Heatoolant

2018 ◽  
Vol 3 (3) ◽  
pp. 268
Author(s):  
Orekhova E.E. ◽  
Andreev V.V. ◽  
Tarasova N.P.
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Energy ◽  
Natural Circulation ◽  
Reactor Core ◽  
Passive Systems ◽  
Two Phase ◽  
Gravitational Forces ◽  
Temperature And Pressure ◽  
The Stability

Concept of safety of nuclear power plants involves in larger quantities the use of passive systems. One of the main passive systems in nuclear power plant – the system of cooling of the reactor core. This system is based on gravitational forces. In this regard, nuclear energy increases the significance of such physical process, as the natural circulation. In addition to the benefits of the system there are drawbacks. There is the instability of the two-phase coolant, pulsation temperature and pressure, rollover and stagnation of circulation. 

Evaluation of Potential to Air Ingestion From RWT Following RAS

2006 ◽  
Author(s):  
Young S. Bang ◽  
Ingoo Kim ◽  
Sweng W. Woo
Keyword(s):  
Water Level ◽  
Power Plants ◽  
Transient Flow ◽  
Cooling System ◽  
Check Valve ◽  
Transient Behavior ◽  
Piping System ◽  
Water Tank ◽  
Two Phase ◽  
Pipe Line

At the Recirculation Actuation Signal (RAS) when the Refueling Water Tank (RWT) water level decreased to a certain value following Loss-of-Coolant Accident (LOCA), the isolation valves of Containment Recirculation Sump (CRS) of the Korean Standard Nuclear Power Plants (KSNP) are open automatically while the RWT isolation valves would be closed manually. It was concerned whether the design has a potential to air ingestion to Emergency Core Cooling System (ECCS) pumps before completion of the manual action to close RWT isolation valves. To support the safety evaluation on this issue including the evaluation of design adequacy, an analysis of the hydraulic transient within the ECCS piping following the RAS in KSNP is performed. RELAP5/MOD3.3 code is used to calculate the transient behavior of the piping network. The code was known to have capability to calculate one-dimensional two-phase transient flow with noncondensible gas in the complex piping. Substantial portion of ECCS are modeled including RWT, CRS, each pipe line from RWT and CRS to connection point with its own isolation valve and check valve, a common pipe line to ECCS header, each pipe line from the header to High Pressure Safety Injection (HPSI) pump, Low Pressure Safety Injection (LPSI) pump, and Containment Spray (CS) pump. Transient hydraulic behavior in the piping system following RAS after LOCA is calculated. It is found that the RWT water level was always higher than the elevation of the check valve at the connecting point by more than 15 ft. It indicates the air intrusion to the check valve can be sufficiently prevented by this amount of water head.

A hybrid cooling system combining self-adaptive single-phase mechanically pumped fluid loop and gravity-immune two-phase spray module

2018 ◽  
Vol 176 ◽  
pp. 194-208 ◽  
Author(s):  
Ji-Xiang Wang ◽  
Yun-Ze Li ◽  
Yi Zhang ◽  
Jia-Xin Li ◽  
Yu-Feng Mao ◽  
...  
Keyword(s):  
Single Phase ◽  
Cooling System ◽  
Two Phase ◽  
Hybrid Cooling ◽  
Self Adaptive

Analysis of Operation Test Results of a High Temperature Phase Change Storage for Parabolic Trough Power Plants With Direct Steam Generation

2012 ◽  
Author(s):  
Doerte Laing ◽  
Markus Eck ◽  
Matthias Hempel ◽  
Wolf-Dieter Steinmann ◽  
Mirko Meyer-Grünefeldt ◽  
...  
Keyword(s):  
Phase Change ◽  
Power Plants ◽  
Natural Circulation ◽  
Heat Transfer Fluid ◽  
Test Results ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Two Phase ◽  
Direct Steam ◽  
Sliding Pressure

For future parabolic trough plants direct steam generation in the receiver pipes is a promising option for reducing the costs of solar thermal energy [1]. These new solar thermal power plants require innovative storage concepts, where the two phase heat transfer fluid poses a major challenge [2]. For the regions where the heat transfer fluid is in a single phase (water or steam), sensible heat storage using molten salt [3] or concrete [4] as storage material can be applied. However, efficient energy storage in the two-phase evaporation/condensation region requires heat storage operation within a narrow temperature range. For this two phase region, a high performance PCM storage technology was developed and demonstrated by DLR. A test module using 14 tons of PCM with 700 kWh capacity was built in 2009 and commissioned in 2010 in a direct steam test loop, set up at the power plant Litoral of Endesa in Carboneras, Spain [5]. The PCM-storage uses Sodium nitrate as phase change material with a melting temperature of 305 °C. Cycle testing has started end of 2010. Cycling tests have proven the expected discharge capacity of approx. 700 kWh for the PCM-storage module. System operation in constant pressure mode and sliding pressure mode has been conducted for the PCM-storage. While in the constant pressure mode a peak performance of the storage of more than 700 kW could be demonstrated, in the sliding pressure mode a constant power output over almost the whole charge and discharge period could be provided. The paper discusses the test results and evaluation for different operation modes for the phase change storage for discharge operation. Charging of the phase change storage is always in a once-through mode. However, for discharge, the steam can be generated either in forced or natural circulation mode or in once-through mode, leading to very different effects for the two-phase flow and filling level inside the heat exchanger pipes in the storage. The effects for forced and natural circulation discharge will be analysed and described in the paper.

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