Methodology for Estimation of Time-Dependent Surface Heat Flux due to Cryogen Spray Cooling

2002 ◽  
Vol 30 (1) ◽  
pp. 19-33 ◽  
Author(s):  
James W. Tunnell ◽  
Jorge H. Torres ◽  
Bahman Anvari
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Spray Cooling ◽  
Surface Heat ◽  
Time Dependent ◽  
Cryogen Spray Cooling ◽  
Estimation Of Time

scholarly journals Effects of mass flow rate and droplet velocity on surface heat flux during cryogen spray cooling

2002 ◽  
Vol 48 (1) ◽  
pp. N1-N6 ◽  
Author(s):  
Emil Karapetian ◽  
Guillermo Aguilar ◽  
Sol Kimel ◽  
Enrique J Lavernia ◽  
J Stuart Nelson
Keyword(s):  
Heat Flux ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Surface Heat Flux ◽  
Spray Cooling ◽  
Surface Heat ◽  
Droplet Velocity ◽  
Cryogen Spray Cooling

scholarly journals Thermally Forced Transients in the Thermohaline Circulation

2015 ◽  
Vol 45 (11) ◽  
pp. 2820-2835 ◽  
Author(s):  
Michael A. Spall
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Thermohaline Circulation ◽  
Numerical Models ◽  
Ocean Basin ◽  
Surface Heat ◽  
Meridional Overturning Circulation ◽  
Time Dependent ◽  
Boundary Current ◽  
Model Calculations

AbstractThe response of a convective ocean basin to variations in atmospheric temperature is explored using numerical models and theory. The results indicate that the general behavior depends strongly on the frequency at which the atmosphere changes relative to the local response time to air–sea heat flux. For high-frequency forcing, the convective region in the basin interior is essentially one-dimensional and responds to the integrated local surface heat flux anomalies. For low-frequency forcing, eddy fluxes from the boundary current into the basin interior become important and act to suppress variability forced by the atmosphere. A theory is developed to quantify this time-dependent response and its influence on various oceanic quantities. The amplitude and phase of the temperature and salinity of the convective water mass, the meridional overturning circulation, the meridional heat flux, and the air–sea heat flux predicted by the theory compare well with that diagnosed from a series of numerical model calculations in both strongly eddying and weakly eddying regimes. Linearized analytic solutions provide direct estimates of each of these quantities and demonstrate their dependence on the nondimensional numbers that characterize the domain and atmospheric forcing. These results highlight the importance of mesoscale eddies in modulating the mean and time-dependent ocean response to atmospheric variability and provide a dynamical framework with which to connect ocean observations with changes in the atmosphere and surface heat flux.

The Effect of Dissolving Salts in Water Sprays Used for Quenching a Hot Surface: Part 2—Spray Cooling

2003 ◽  
Vol 125 (2) ◽  
pp. 333-338 ◽  
Author(s):  
Qiang Cui ◽  
Sanjeev Chandra ◽  
Susan McCahan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Spray Cooling ◽  
Surface Heat ◽  
Water Sprays ◽  
Nucleate Boiling Heat Transfer ◽  
Hot Surface

The effect of adding one of three salts (NaCl, Na2SO4 or MgSO4) to water sprayed on a hot surface was studied experimentally. A copper test surface was heated to 240°C and quenched with a water spray. The variation of surface temperature during cooling was recorded, and the surface heat flux calculated from these measurements. Surface heat flux during cooling with pure water sprays was compared with that obtained using salt solutions. Dissolved NaCl or Na2SO4 increased nucleate boiling heat transfer, but had little effect on transition boiling during spray cooling. MgSO4 increased both nucleate and transition boiling heat flux. Enhanced nucleate boiling was attributed to foaming in the liquid film generated by the dissolved salts. MgSO4 produced the largest increase in nucleate boiling heat transfer, Na2SO4 somewhat less and NaCl the least. A concentration of 0.2 mol/l of MgSO4 produced the greatest heat flux enhancement; higher salt concentrations did not result in further improvements. During transition boiling particles of MgSO4 adhered to the heated surface, raising surface roughness and increasing heat transfer. Addition of MgSO4 reduced the time required to cool a hot surface from 240°C to 120°C by an order of magnitude.

scholarly journals The Fundamental and Application of Surface Heat Flux Estimation by Inverse Method in Cryogen Spray Cooling

2020 ◽  
Author(s):  
Bin Chen ◽  
Jia-Meng Tian ◽  
Zhi-Fu Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Global Warming ◽  
Global Warming Potential ◽  
Surface Heat Flux ◽  
Spray Cooling ◽  
Surface Heat ◽  
Flux Estimation ◽  
Filter Solution ◽  
2D Filter

Surface heat flux is an important parameter in various industrial applications, which is often estimated based on measured temperature by solving inverse heat conduction problem (IHCP). In this chapter, the available IHCP methods including sequential function specification (SFS), transfer function (TF) and Duhamel’s theorem were compared, taking the example of surface heat flux estimation during spray cooling. The Duhamel’s theorem was improved to solve 1D multi-layer ICHP. Considering the significant nonuniformity of heat transfer, the 2D filter solution method was proposed to estimate surface heat flux for 2D multi-layer mediums. The maximum heat flux calculated by the 1D method was underestimated by 60% than that calculated by 2D filter solution, indicating that the lateral heat transfer cannot be ignored. The cooling performances based on 2D filter solution demonstrated that substituting the environment friendly R1234yf for R134a can remarkably reduce global warming potential to <1, but its cooling capacity is insufficient. The effective heat flux of R1234yf can be enhanced by 18.8% by reducing the nozzle diameter and decreasing the back pressure, providing the theoretical basis for the clinical potential substitution of R1234yf with low global warming potential (GWP) for commercial R134a with high GWP in laser dermatology.

Heat wave phenomena in solids subjected to time dependent surface heat flux

2007 ◽  
Vol 44 (4) ◽  
pp. 381-392 ◽  
Author(s):  
G. Heidarinejad ◽  
R. Shirmohammadi ◽  
M. Maerefat
Keyword(s):  
Heat Flux ◽  
Heat Wave ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Time Dependent ◽  
Wave Phenomena

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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