Experimental Investigation on Heat Transfer Mechanism of Air-Blast-Spray-Cooling System with a Two-Phase Ejector Loop for Aeronautical Application

This paper presents an air-oriented spray cooling system (SCS) integrated with a two-phase ejector for the thermal management system. Considering its aeronautical application, the spray nozzle in the SCS is an air-blast one. Heat transfer performance (HTP) of air-water spray cooling was studied experimentally on the basis of the ground-based test. Factors including pressure difference between water-inlet-pressure (WIP) and spray cavity one (PDWIC) and the spray volumetric flow rate (SVFR) were investigated and discussed. Under a constant operating condition, the cooling capacity can be promoted by the growth factors of the PDWIC and SVFR with the values from 51.90 kPa to 235.35 kPa and 3.91 L ⋅ h − 1 to 14.53 L ⋅ h − 1 , respectively. Under the same heating power, HTP is proportional to the two dimensionless parameters Reynolds number and Weber number due to the growth of droplet-impacting velocity and droplet size as the increasing of PDWIC or SVFR. Additionally, compared with the factor of the droplet size, the HTP is more sensitive to the variation in the droplet-impacting velocity. Based on the experimental data, an empirical experimental correlation for the prediction of the dimensionless parameter Nusselt number in the non-boiling region with the relative error of only ± 10 % was obtained based on the least square method.

Download Full-text

Peristaltic Carreau-Yasuda nanofluid flow and mixed heat transfer analysis in an asymmetric vertical and tapered wavy wall channel

Reports in Mechanical Engineering ◽

10.31181/rme200101128h ◽

2020 ◽

Vol 1 (1) ◽

pp. 128-140 ◽

Cited By ~ 1

Author(s):

Mohammad Hatami ◽

◽

D Jing ◽

Keyword(s):

Heat Transfer ◽

Least Square Method ◽

Weissenberg Number ◽

Least Square ◽

Heat Transfer Analysis ◽

Phase Method ◽

Nanofluid Flow ◽

Two Phase ◽

Nanoparticles Concentration ◽

The Right

In this study, two-phase asymmetric peristaltic Carreau-Yasuda nanofluid flow in a vertical and tapered wavy channel is demonstrated and the mixed heat transfer analysis is considered for it. For the modeling, two-phase method is considered to be able to study the nanoparticles concentration as a separate phase. Also it is assumed that peristaltic waves travel along X-axis at a constant speed, c. Furthermore, constant temperatures and constant nanoparticle concentrations are considered for both, left and right walls. This study aims at an analytical solution of the problem by means of least square method (LSM) using the Maple 15.0 mathematical software. Numerical outcomes will be compared. Finally, the effects of most important parameters (Weissenberg number, Prandtl number, Brownian motion parameter, thermophoresis parameter, local temperature and nanoparticle Grashof numbers) on the velocities, temperature and nanoparticles concentration functions are presented. As an important outcome, on the left side of the channel, increasing the Grashof numbers leads to a reduction in velocity profiles, while on the right side, it is the other way around.

Download Full-text

Experimental Investigation of Spray Cooling Heat Transfer on Circular Grooved Surface

Volume 2: Heat Transfer Equipment; Heat Transfer in Multiphase Systems; Heat Transfer Under Extreme Conditions; Nanoscale Transport Phenomena; Theory and Fundamental Research in Heat Transfer; Thermophysical Properties; Transport Phenomena in Materials Processing and Manufacturing ◽

10.1115/ht2017-4928 ◽

2017 ◽

Cited By ~ 2

Author(s):

Azzam S. Salman ◽

Jamil A. Khan

Keyword(s):

Heat Transfer ◽

Flow Rate ◽

Cooling System ◽

Volumetric Flow Rate ◽

Target Surface ◽

Spray Cooling ◽

Operating Conditions ◽

Low Flow ◽

Inlet Temperature ◽

Flow Rates

An experimental study was conducted in a closed loop spray cooling system working with deionized water as a cooling medium, to investigate the effects of surface modification on the spray cooling heat transfer enhancement in the single-phase region. Plain copper surface with diameter 1.5 cm and an enhanced surface with circular grooves were tested under different operating conditions. The volumetric flow rate of the coolant ranged from 115 mL/min to 177 mL/min., and the water inlet temperature was kept between 21–23 °C. Also, the distances between the nozzle and the target surface were varied at 8, 10, and 12 mm respectively. The results show that the distance between the nozzle and the target surface did not have a significant effect on the heat transfer performance for the low flow rates, while it has a slight effect on high flow rates for both surfaces. Also, increasing the liquid volumetric flow rate increases the amount of heat removed, and the heat transfer coefficient for both surfaces. Moreover, the maximum enhancement ratios achieved were 23.4% and 31% with volumetric flow rates of 153 mL/min, and 177 mL/min respectively.

Download Full-text

Two-phase nanofluid condensation and heat transfer modeling using least square method (LSM) for industrial applications

Heat and Mass Transfer ◽

10.1007/s00231-016-1964-5 ◽

2017 ◽

Vol 53 (6) ◽

pp. 2061-2072 ◽

Cited By ~ 11

Author(s):

M. Hatami ◽

S. Mosayebidorcheh ◽

D. Jing

Keyword(s):

Heat Transfer ◽

Least Square Method ◽

Industrial Applications ◽

Least Square ◽

Two Phase ◽

Heat Transfer Modeling

Download Full-text

Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side

Archives of Thermodynamics ◽

10.2478/v10173-010-0027-4 ◽

2010 ◽

Vol 31 (4) ◽

pp. 51-59 ◽

Cited By ~ 3

Author(s):

Henryk Bieliński ◽

Jarosław Mikielewicz

Keyword(s):

Heat Transfer ◽

Personal Computer ◽

Two Phase Flow ◽

Cooling System ◽

Cooling Capacity ◽

Phase Flow ◽

Two Phase ◽

Vertical Side ◽

Horizontal Side ◽

Energy Balances

Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical sideIn the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.

Download Full-text

HEAT TRANSFER PERFORMANCE OF A ROOF-SPRAY COOLING SYSTEM EMPLOYING THE TRANSFER FUNCTION METHOD

Proceeding of International Heat Transfer Conference 10 ◽

10.1615/ihtc10.40 ◽

1994 ◽

Author(s):

J. A. Clements ◽

S.A. Sherif

Keyword(s):

Heat Transfer ◽

Transfer Function ◽

Function Method ◽

Heat Transfer Performance ◽

Cooling System ◽

Spray Cooling ◽

Transfer Performance ◽

Transfer Function Method

Download Full-text

Development of Cooling System for a Large Area at High Heat Flux by Using Flow Boiling in Narrow Channels

ASME 2009 7th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2009-82279 ◽

2009 ◽

Author(s):

Shinichi Miura ◽

Yukihiro Inada ◽

Yasuhisa Shinmoto ◽

Haruhiko Ohta

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Flow Rate ◽

Mass Velocity ◽

Cooling System ◽

Volumetric Flow Rate ◽

High Heat ◽

High Heat Flux ◽

Gap Size ◽

Heated Channel

Advance of an electronic technology has caused the increase of heat generation density for semiconductors densely integrated. Thermal management becomes more important, and a cooling system for high heat flux is required. It is extremely effective to such a demand using flow boiling heat transfer because of its high heat removal ability. To develop the cooling system for a large area at high heat flux, the cold plate structure of narrow channels with auxiliary unheated channel for additional liquid supply was devised and confirmed its validity by experiments. A large surface of 150mm in heated length and 30mm in width with grooves of an apex angle of 90 deg, 0.5mm depth and 1mm in pitch was employed. A structure of narrow rectangular heated channel between parallel plates with an unheated auxiliary channel was employed and the heat transfer characteristics were examined by using water for different combinations of gap sizes and volumetric flow rates. Five different liquid distribution modes were tested and their data were compared. The values of CHF larger than 1.9×106W/m2 for gap size of 2mm under mass velocity based on total volumetric flow rate and on the cross section area of main heated channel 720kg/m2s or 1.7×106W/m2 for gap size of 5mm under 290kg/m2s were obtained under total volumetric flow rate 4.5×10−5m3/s regardless of the liquid distribution modes. Under several conditions, the extensions of dry-patches were observed at the upstream location of the main heated channel resulting burnout not at the downstream but at the upstream. High values of CHF larger than 2×106W/m2 were obtained only for gap size of 2mm. The result indicates that higher mass velocity in the main heated channel is more effective for the increase in CHF. It was clarified that there is optimum flow rate distribution to obtain the highest values of CHF. For gap size of 2mm, high heat transfer coefficient as much as 7.4×104W/m2K were obtained at heat flux 1.5×106W/m2 under mass velocity 720kg/m2s based on total volumetric flow rate and on the cross section area of main heated channel. Also to obtain high heat transfer coefficient, it is more useful to supply the cooling liquid from the auxiliary unheated channel for additional liquid supply in the transverse direction perpendicular to the flow in the main heated channel.

Download Full-text

Parametric study of heat transfer characteristics of enhanced surfaces in a spray cooling system: An experimental investigation

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2020.115824 ◽

2021 ◽

Vol 183 ◽

pp. 115824

Author(s):

Azzam S. Salman ◽

Nabeel M. Abdulrazzaq ◽

Amitav Tikadar ◽

Saad K. Oudah ◽

Jamil A. Khan

Keyword(s):

Heat Transfer ◽

Experimental Investigation ◽

Parametric Study ◽

Cooling System ◽

Spray Cooling ◽

Heat Transfer Characteristics ◽

Transfer Characteristics

Download Full-text

The Effects of Spraying Parameters on Spray Cooling Heat Transfer Performance in the Non-Boiling Regime

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2017-71449 ◽

2017 ◽

Author(s):

Azzam S. Salman ◽

Jamil A. Khan

Keyword(s):

Heat Transfer ◽

Cooling System ◽

Target Surface ◽

Spray Cooling ◽

Operating Conditions ◽

Droplet Velocity ◽

Inlet Pressure ◽

Working Fluid ◽

Inlet Temperature ◽

Spraying Parameters

Experiments were conducted in a closed loop spray cooling system working with deionized water as a working fluid. This study was performed to investigate the effect of the spraying parameters, such as Sauter mean diameter (SMD), the droplet velocity, and the residual velocity on the spray cooling heat transfer in the non-boiling region. Thermal effects on plain and modified surfaces with circular grooves were examined under different operating conditions. The inlet pressure of the working fluid was varied from 78.6 kPa to 183.515kPa, and the inlet temperature was kept between 21–22 °C. The distance between the nozzle and the target surface 10 mm. The results showed that increasing the coolant inlet pressure increases the droplet velocity and the number of droplets produced while decreasing the droplet size. As a consequence of these changes, increasing inlet pressure improved the heat transfer characteristics of both surfaces.

Download Full-text

On Efficient Passive Cooling of Control Rod Drivers

Volume 2: Plant Systems, Construction, Structures and Components; Next Generation Reactors and Advanced Reactors ◽

10.1115/icone21-16449 ◽

2013 ◽

Author(s):

A. N. Gershuni ◽

A. P. Nishchik ◽

V. G. Razumovskiy ◽

I. L. Pioro

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

High Performance ◽

Cooling System ◽

Vertical Channel ◽

Passive Cooling ◽

Primary Circuit ◽

Two Phase ◽

Primary Coolant ◽

Control Rod

Experimental research of natural convection and the ways of its suppression in an annular vertical channel to simulate the conditions of cooling the control rod drivers of the reactor protection system (RPS) in its so-called wet design, where the drivers are cooled by primary circuit water supplied due to the system that includes branched pipelines, valves, pump, heat exchanger, etc., is reported. Reliability of the drivers depends upon their temperature ensured by operation of an active multi-element cooling system. Its replacement by an available passive cooling system is possible only under significant suppression of natural convection in control rod channel filled with primary coolant. The methods of suppression of natural convection proposed in the work have demonstrated the possibility both of minimization of axial heat transfer and of almost complete elimination of temperature non-uniformity and oscillation inside the channel under the conditions of free travel of moving element (control rod) in it. The obtained results widen the possibilities of substitution of the active systems of cooling the RPS drivers by reliable passive systems, such as high-performance heat-transfer systems of evaporation-condensation type with heat pipes or two-phase thermosyphons as heat-transferring elements.

Download Full-text