Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen

Cryogenics ◽  
2003 ◽  
Vol 43 (10-11) ◽  
pp. 589-596 ◽  
Author(s):  
Ho-Myung Chang ◽  
Yeon Suk Choi ◽  
Steven W. Van Sciver ◽  
Kyeong Dal Choi
Keyword(s):  
Natural Convection ◽  
Liquid Nitrogen ◽  
Cooling System ◽  
Cryogenic Cooling ◽  
Subcooled Liquid

Experiment on natural convection of subcooled liquid nitrogen

2005 ◽  
pp. 861-864
Author(s):  
Yeon Suk Choi ◽  
Ho-Myung Chang ◽  
Steven W. Van Sciver
Keyword(s):  
Natural Convection ◽  
Liquid Nitrogen ◽  
Subcooled Liquid

scholarly journals Numerical Study of the Effects of Injection Fluctuations on Liquid Nitrogen Spray Cooling

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 564 ◽  
Author(s):  
Rong Xue ◽  
Yixiao Ruan ◽  
Xiufang Liu ◽  
Liang Chen ◽  
Liqiang Liu ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Cooling System ◽  
Numerical Study ◽  
Spray Cooling ◽  
Volume Averaging ◽  
Cryogenic Cooling ◽  
Droplet Distribution ◽  
Cooling Effects ◽  
Spray Field ◽  
Lower Temperature

Spray cooling with liquid nitrogen is increasingly utilized as an efficient approach to achieve cryogenic cooling. Effects of injection mass flow rate fluctuations on the evaporation, temperature distribution, and droplet distribution of a spray field were examined by employing a validated Computational Fluid Dynamics (CFD) numerical model. The numerical results indicated that injection fluctuations enhanced the volume-averaging turbulent kinetic energy and promoted the evaporation of the whole spray field. The strengthened mass and heat transfer between the liquid nitrogen droplets and the surrounding vapor created by the fluctuating injection led to a lower temperature of the whole volume. A relatively smaller droplet size and a more inhomogeneous droplet distribution were obtained under the unsteady inlet. The changes of the frequency and the amplitude of the fluctuations had little effects on the overall spray development. The results could enrich the knowledge of the relation between the inevitable fluctuations and the overall spray development and the cooling performance in a practical spray cooling system with cryogenic fluids.

Low Cost, Flow-Rate-Controllable Cryogenic Cooling System for Manufacturing Processes

2014 ◽  
Author(s):  
Louai Al Khawam ◽  
Ali Abu Haidar ◽  
Mohammad Mansour ◽  
Fadi El Dimassi ◽  
Ali Ammouri ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Cooling System ◽  
Low Cost ◽  
Minimum Quantity Lubrication ◽  
Cryogenic Cooling ◽  
Work Piece ◽  
Cooling Fluid ◽  
Valve Opening ◽  
Temperature And Pressure ◽  
Flexible Applications

In-process cryogenic cooling in fabrication processes is known to — among other benefits — extend tool life and improve the surface properties of a work-piece. To provide flexible applications of cryogenic cooling, control of the cooling fluid is required. The commercial availability of such a control system is limited and, if available, is rather expensive. This paper reports on the design and build of a low-cost controlled cryogenic cooling system. The system supplies an adjustable flow of liquid nitrogen to the work-piece under process. Flow control is accomplished by controlling the temperature and/or pressure of an intermediate actuator while controlling the flow via an actuated electronic valve. Using a custom code using LabVIEW, the user would specify the cooling parameters and the system will automatically adjust the temperature/pressure signal input to the actuator as well as the valve opening while monitoring both temperature and pressure of the actuator. Flow development of liquid nitrogen inside the system was modeled using ANSYS. The closed loop system will guarantee minimum use of liquid nitrogen in an as-needed basis similar to minimum quantity lubrication.

scholarly journals Development of cooling system for 66/6.9kV-20MVA REBCO superconducting transformers with Ne turbo-Brayton refrigerator and subcooled liquid nitrogen

2015 ◽  
Vol 101 ◽  
pp. 012026 ◽  
Author(s):  
M Iwakuma ◽  
K Adachi ◽  
K Yun ◽  
K Yoshida ◽  
S Sato ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Cooling System ◽  
Subcooled Liquid

A conduction-cooled stage for high-resolution Cryo-SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1282-1283
Author(s):  
John G. Sheehan
Keyword(s):  
High Resolution ◽  
Liquid Nitrogen ◽  
Mechanical Stability ◽  
Cooling System ◽  
Cold Trap ◽  
Nitrogen Gas ◽  
Particulate Suspensions ◽  
Advantages And Disadvantages ◽  
Convection Cooling ◽  
Styrene Butadiene

The goal is to examine with high resolution cryo-SEM aqueous particulate suspensions used in coatings for printable paper. A metal-coating chamber for cryo-preparation of such suspensions was described previously. Here, a new conduction-cooling system for the stage and cold-trap in an SEM specimen chamber is described. Its advantages and disadvantages are compared to a convection-cooling system made by Hexland (model CT1000A) and its mechanical stability is demonstrated by examining a sample of styrene-butadiene latex.In recent high resolution cryo-SEM, some stages are cooled by conduction, others by convection. In the latter, heat is convected from the specimen stage by cold nitrogen gas from a liquid-nitrogen cooled evaporative heat exchanger. The advantage is the fast cooling: the Hexland CT1000A cools the stage from ambient temperature to 88 K in about 20 min. However it consumes huge amounts of liquid-nitrogen and nitrogen gas: about 1 ℓ/h of liquid-nitrogen and 400 gm/h of nitrogen gas. Its liquid-nitrogen vessel must be re-filled at least every 40 min.

Experimental Evaluation of 1 kW-class Prototype REBCO Fully Superconducting Synchronous Motor Cooled by Subcooled Liquid Nitrogen for E-Aircraft

2021 ◽  
pp. 1-1
Author(s):  
Hiromasa Sasa ◽  
Masataka Iwakuma ◽  
Kohichi Yoshida ◽  
Seiki Sato ◽  
Teruyoshi Sasayama ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Experimental Evaluation ◽  
Synchronous Motor ◽  
Subcooled Liquid

The influence of machining parameters using cryogenic cooling system

2021 ◽  
Author(s):  
Arie Yudha Budiman ◽  
Amrifan Saladin Mohruni ◽  
Safian Sharif ◽  
Aneka Firdaus ◽  
Bima Satria Nugraha
Keyword(s):  
Cooling System ◽  
Cryogenic Cooling ◽  
Machining Parameters

Improvement of Temperature Evaluation Model of Biological Shielding Concrete for HTTR Test Simulating LOFC With VCS Inactive

2013 ◽  
Author(s):  
Shoji Takada ◽  
Shunki Yanagi ◽  
Kazuhiko Iigaki ◽  
Masanori Shinohara ◽  
Daisuke Tochio ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Thermal Radiation ◽  
Cooling System ◽  
Evaluation Model ◽  
Reactor Core ◽  
Reactor Power ◽  
Coolant Temperature ◽  
Water Cooling ◽  
Reactor Outlet

HTTR is a helium gas cooled graphite-moderated HTGR with the rated power 30 MWt and the maximum reactor outlet coolant temperature 950°C. The vessel cooling system (VCS), which is composed of thermal reflector plates, cooling panel composed of fins connected between adjacent water cooling tubes, removes decay heat from reactor core by heat transfer of thermal radiation, conduction and natural convection in case of loss of forced cooling (LOFC). The metallic supports are embedded in the biological shielding concrete to support the fins of VCS. To verify the inherent safety features of HTGR, the LOFC test is planned by using HTTR with the VCS inactive from an initial reactor power of 9 MWt under the condition of LOFC while the reactor shut-down system disabled. In this test, the temperature distribution in the biological shielding concrete is prospected locally higher around the support because of thermal conduction in the support. A 2-dimensional symmetrical model was improved to simulate the heat transfer to the concrete through the VCS support in addition to the heat transfer thermal radiation and natural convection. The model simulated the water cooling tubes setting horizontally at the same pitch with actual configuration. The numerical results were verified in comparison with the measured data acquired from the test, in which the RPV was heated up to around 110 °C without nuclear heating with the VCS inactive, to show that the temperature is locally high but kept sufficiently low around the support in the concrete due to sufficient thermal conductivity to the cold temperature region.

Cavitation flow instability of subcooled liquid nitrogen in converging–diverging nozzles

Cryogenics ◽  
2012 ◽  
Vol 52 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Katsuhide Ohira ◽  
Tadashi Nakayama ◽  
Takayoshi Nagai
Keyword(s):  
Liquid Nitrogen ◽  
Flow Instability ◽  
Cavitation Flow ◽  
Subcooled Liquid
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