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.

Numerical study on the performance of a two-nozzle spray cooling system under different conditions

2020 ◽  
Vol 152 ◽  
pp. 106291 ◽  
Author(s):  
Zhiyu Zhang ◽  
Suoying He ◽  
Mingxuan Yan ◽  
Ming Gao ◽  
Yuetao Shi ◽  
...  
Keyword(s):  
Cooling System ◽  
Numerical Study ◽  
Spray Cooling

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

An experimental and numerical study on liquid nitrogen spray cooling for cryotherapy

Cryobiology ◽  
2018 ◽  
Vol 80 ◽  
pp. 179 ◽  
Author(s):  
Chandrika Kumari ◽  
Amitesh Kumar ◽  
Sunil Kumar Sarangi ◽  
A. Thirugnanam
Keyword(s):  
Liquid Nitrogen ◽  
Numerical Study ◽  
Spray Cooling

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.

Design and analysis of a cooling system for a supersonic exhaust diffuser

2019 ◽  
Vol 233 (14) ◽  
pp. 5253-5263 ◽  
Author(s):  
M Farahani ◽  
N Fouladi ◽  
AR Mirbabaei
Keyword(s):  
High Altitude ◽  
Cooling System ◽  
Numerical Study ◽  
Numerical Technique ◽  
Spray Cooling ◽  
Space Mission ◽  
Test Facility ◽  
Navier Stokes ◽  
Phase Method ◽  
Plume Temperature

High-altitude test facilities are usually used to evaluate the performance of space mission engines. The supersonic exhaust diffuser, a main part of high-altitude test facility, provides the required test cell vacuum conditions by self-pumping the nozzle exhaust gases to the atmosphere. However, the plume temperature is often much higher than the temperature the diffuser structure is able to withstand, usually above 2500 K. In this study, an efficient cooling system is designed and analyzed to resolve the thermal problem. A water spray cooling technique is preferred among various existing techniques. Here, a new algorithm is developed for a spray cooling system for a supersonic exhaust diffuser. This algorithm uses a series of experimental and geometrical relationships to resize the governing parameters and remove the required heat flux from the diffuser surface. The efficiency of the newly designed cooling system is evaluated via numerical simulations. The utilized numerical technique is based on the discrete-phase method. Various computational studies are accomplished to enhance the accuracy of numerical prediction and validation. The present numerical study is validated using experimental results. The results show that the realizable k-ɛ method is superior compared to other Reynolds-averaged Navier–Stokes models.

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.

Spray Cooling for Time Resolved Emission Measurements of ICs

2004 ◽  
Author(s):  
Rama R. Goruganthu ◽  
David Bethke ◽  
Shawn McBride ◽  
Tom Crawford ◽  
Jonathan Frank ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Performance ◽  
Flip Chip ◽  
Cooling System ◽  
Spray Cooling ◽  
Junction Temperature ◽  
Maximum Temperature ◽  
Uniform Heat Flux ◽  
High Heat Flux ◽  
Time Resolved

Abstract Spray cooling is implemented on an engineering tool for Time Resolved Emission measurements using a silicon solid immersion lens to achieve high spatial resolution and for probing high heat flux devices. Thermal performance is characterized using a thermal test vehicle consisting of a 4x3 array of cells each with a heater element and a thermal diode to monitor the temperature within the cell. The flip-chip packaged TTV is operated to achieve uniform heat flux across the die. The temperature distribution across the die is measured on the 4x3 grid of the die for various heat loads up to 180 W with corresponding heat flux of 204 W/cm2. Using water as coolant the maximum temperature differential across the die was about 30 °C while keeping the maximum junction temperature below 95 °C and at a heat flux of 200 W/cm2. Details of the thermal performance of spray cooling system as a function of flow rate, coolant

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

Sign in / Sign up

Export Citation Format

Share Document