scholarly journals Ground detector for a floating, high current dc system. [3. 6 MW dc resistance heater test loop in Heat Transfer Lab of Savannah River Lab]

1976 ◽  
Author(s):  
W.J. Woodward
Keyword(s):  
Heat Transfer ◽  
High Current ◽  
Savannah River ◽  
Dc System ◽  
Test Loop ◽  
Dc Resistance

Upgrade and Shakedown Test of a High Temperature Fluoride Salt Test Loop

2018 ◽  
Author(s):  
Xiangbo Kong ◽  
Yuan Fu ◽  
Jianyu Zhang ◽  
Huiju Lu ◽  
Naxiu Wang
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Storage Tank ◽  
Base Alloy ◽  
High Vacuum ◽  
Electric Heater ◽  
Batch Mode ◽  
Test Loop

A FLiNaK high temperature test loop, which was designed to support the Thorium Molten Salt Reactor (TMSR) program, was constructed in 2012 and is the largest engineering-scale fluoride loop in the world. The loop is built of Hastelloy C276 and is capable of operating at the flow rate up to 25m3/h and at the temperature up to 650°C. It consists of an overhung impeller sump-type centrifugal pump, an electric heater, a heat exchanger, a freeze valve and a mechanical one, a storage tank, etc. Salt purification was conducted in batch mode before it was transferred to and then stored in the storage tank. The facility was upgraded in three ways last year, with aims of testing a 30kW electric heater and supporting the heat transfer experiment in heat exchanger. Firstly, an original 100kW electric heater was replaced with a 335kW one to compensate the overlarge heat loss in the radiator. A pressure transmitter was subsequently installed in the inlet pipe of this updated heater. Finally, a new 30kW electric heater was installed between the pump and radiator, the purpose of which was to verify the core’s convective heat transfer behavior of a simulator design of TMSR. Immediately after these above works, shakedown test of the loop was carried out step by step. At first the storage tank was gradually preheated to 500°C so as to melt the frozen salt. Afterwards, in order to make the operation of transferring salt from storage tank to loop achievable, the loop system was also preheated to a relatively higher temperature 530°C. Since the nickel-base alloy can be severely corroded by the FLiNaK salt once the moisture and oxygen concentration is high, vacuum pumping and argon purging of the entire system were alternatively performed throughout the preheating process, with the effect of controlling them to be lower than 100ppm. Once the salt was transferred into the loop, the pump was immediately put into service. At the very beginning of operation process, it was found that flow rate in the main piping could not be precisely measured by the ultrasonic flow meter. Ten days later, the pump’s dry running gas seal was out of order. As a result, the loop had to be closed down to resolve these issues.

Flow and heat transfer in a closed loop thermosyphon Part II – experimental simulation

2007 ◽  
Vol 18 (4) ◽  
pp. 41-48 ◽  
Author(s):  
J.C. Ruppersberg ◽  
R.T. Dobson
Keyword(s):  
Heat Transfer ◽  
Closed Loop ◽  
Cooling System ◽  
Operating Conditions ◽  
Experimental Simulation ◽  
Theoretical Modelling ◽  
Working Fluid ◽  
Small Scale ◽  
System A ◽  
Test Loop

A closed loop thermosyphon is an energy transfer device that employs thermally induced density gra-dients to induce circulation of the working fluid thereby obviating the need for any mechanical moving parts such as pumps and pump controls. This increases the reliability and safety of the cool-ing system and reduces installation, operation and maintenance costs. These characteristics make it a particularly attractive option for the cavity cooling system of the Pebble Bed Modular Reactor (PBMR). Loop thermosyphons are however, known to become unstable under certain initial and operating conditions. It is therefore necessary to conduct an experimental and theoretical study of the start-up and transient behaviour of such a system. A small scale test loop was built representing a section of a concept cooling system. A number of representative yet typical experimental temperature and flow rate curves for a range of initial and boundary condi-tions were generated, plotted and are given as a function of time. These curves show that oscillatory temperature and flow occurred that was dependent on the differing design and operating conditions. A number of theoretical modelling and actual cooling system design problem areas were identified. These problem areas need to be addressed if more accu-racy is required to capture the erratic and ostensibly chaotic heat transfer behaviour of the loop.

Experimental Investigation on Heat Transfer and Pressure Drop of Supercritical Water Flows in 2×2 Bundle With Wire Wraps

2017 ◽  
Author(s):  
Li Hong-bo ◽  
Hu Zhen-xiao ◽  
Lu Dong-hua ◽  
Gu Han-yang
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Pressure Drop ◽  
Supercritical Water ◽  
Critical Conditions ◽  
Bulk Temperature ◽  
Experimental Conditions ◽  
Water Flows ◽  
Dc Power ◽  
Test Loop

An experimental investigation on heat transfer of supercritical water and transient heat transfer during pressure drop from supercritical to sub-critical conditions in a 2×2 bundle with two channels has been carried out on the supercritical water multipurpose test loop II (SWAMUP-II). The bundle consists of four heated rods with an O.D. of 10 mm and a pitch-to-diameter ratio of 1.18. The 2×2 bundle with wire wrap is installed into a square assembly box with rounded corners by which the test section is separated into two channels. Water flows downward in the first channel between the pressure tube and the assembly box, and then turns upward in the second channel inside the assembly box to cool the four heated rods, which are directly heated by DC power. The experimental conditions are as follows: pressure ranging from 16 to 26 MPa, mass flux from 400 to 1450 kg/m2s, heat flux from 250 to 1000 kW/m2, bulk temperature from 280 to 500 °C, and pressure drop rate of 1 and 2 MPa/min. The experimental data are obtained and heat transfer characteristics discussed.

Flow and Heat Transfer Characteristics of a Natural Circulation Evaporative Cooling System for Electronic Components

2004 ◽  
Vol 126 (3) ◽  
pp. 317-324 ◽  
Author(s):  
Hiroshi Honda ◽  
ZhengGuo Zhang ◽  
Nobuo Takata
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Test Section ◽  
Cooling System ◽  
Natural Circulation ◽  
Electronic Components ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Test Loop

Experiments were conducted to study the flow and heat transfer characteristics of a natural circulation liquid cooling system for electronic components. The test loop consisted of a horizontal test section, a horizontal evaporator, a vertical tube, a horizontal condenser, a rubber bag attached at the exit of the condenser, a downcomer, a mass flow meter, and a liquid subcooler. The loop height H was set at either 250 or 450 mm. FC-72 was filled in the test loop up to some level of loop height and the upper part was filled with air. During the operation of the cooling system, the rubber bag expanded and stored the mixture of generated vapor and air. Thus the inner pressure was maintained at atmospheric pressure. In the test section, a silicon chip with dimensions of 10×10×0.5 mm3 was attached at the bottom surface of a horizontal duct with dimensions of 10×14 mm2. A smooth chip and four chips with square micro-pin-fins with 150 to 300 μm in fin height were tested. The duct height s was set at 10 mm for most of the experiments. The cases of s=1 and 25 mm were also tested for one of the micro-pin-finned chips. For each H, the average flow rate of FC-72 was correlated well as a function of the static pressure difference between the two vertical tubes. All chips showed the boiling curve similar to that for pool boiling except that the critical heat flux was lower for the natural circulation loop. For all chips tested, the maximum allowable heat flux qmax increased monotonically with increasing liquid subcooling ΔTsub. Comparison of the results for s=1, 10 and 25 mm revealed that the highest qmax was obtained with s=10 mm. The values of qmax for s=1 and 25 mm were 36–46% and 87–90% of that for s=10 mm, respectively. The maximum value of qmax=56 W/cm2 was obtained by one of the micro-pin-finned chips at s=10 mm and ΔTsub=35 K.

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