Power Plant Testing of Ultrasonic Measurements of Temperature Distributions and Heat Fluxes to Heat Exchange Surfaces

2021 ◽  
Author(s):  
Kenneth Walton ◽  
Mason John ◽  
Mikhail Skliar
Keyword(s):  
Heat Exchange ◽  
Power Plant ◽  
Heat Fluxes ◽  
Temperature Distributions ◽  
Ultrasonic Measurements

scholarly journals Challenges in Modeling Turbulent Heat Fluxes to Snowpacks in Forest Clearings

2018 ◽  
Vol 19 (10) ◽  
pp. 1599-1616 ◽  
Author(s):  
Jonathan P. Conway ◽  
John W. Pomeroy ◽  
Warren D. Helgason ◽  
Nicholas J. Kinar
Keyword(s):  
Heat Exchange ◽  
Surface Temperature ◽  
Latent Heat ◽  
Turbulent Fluxes ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Snow Surface ◽  
Turbulent Heat Exchange ◽  
Uncertainty Estimates ◽  
Model Tuning

Abstract Forest clearings are common features of evergreen forests and produce snowpack accumulation and melt differing from that in adjacent forests and open terrain. This study has investigated the challenges in specifying the turbulent fluxes of sensible and latent heat to snowpacks in forest clearings. The snowpack in two forest clearings in the Canadian Rockies was simulated using a one-dimensional (1D) snowpack model. A trade-off was found between optimizing against measured snow surface temperature or snowmelt when choosing how to specify the turbulent fluxes. Schemes using the Monin–Obukhov similarity theory tended to produce negatively biased surface temperature, while schemes that enhanced turbulent fluxes, to reduce the surface temperature bias, resulted in too much melt. Uncertainty estimates from Monte Carlo experiments showed that no realistic parameter set could successfully remove biases in both surface temperature and melt. A simple scheme that excludes atmospheric stability correction was required to successfully simulate surface temperature under low wind speed conditions. Nonturbulent advective fluxes and/or nonlocal sources of turbulence are thought to account for the maintenance of heat exchange in low-wind conditions. The simulation of snowmelt was improved by allowing enhanced latent heat fluxes during low-wind conditions. Caution is warranted when snowpack models are optimized on surface temperature, as model tuning may compensate for deficiencies in conceptual and numerical models of radiative, conductive, and turbulent heat exchange at the snow surface and within the snowpack. Such model tuning could have large impacts on the melt rate and timing of the snow-free transition in simulations of forest clearings within hydrological and meteorological models.

scholarly journals The influence of the charge shape on heat exchange of a recessed nozzle

2021 ◽  
Vol 2057 (1) ◽  
pp. 012013
Author(s):  
B Ya Benderskiy ◽  
A A Chernova
Keyword(s):  
Heat Exchange ◽  
Power Plant ◽  
Combustion Products ◽  
Triangular Form ◽  
Topological Features ◽  
Exchange Processes ◽  
Charge Shape ◽  
Intensification Of Heat Exchange ◽  
Thermally Conductive ◽  
Control Volumes

Abstract The paper deals with the numerical simulation of the flow of thermally conductive viscous gaseous combustion products in the flow paths of a power plant. The influence of the shape of the mass supply surface on the gas dynamics and heat exchange near the recessed nozzle of the power plant is investigated. The coupled problem of heat exchange is solved by the method of control volumes. It is shown that the compensator geometry determines the localization of both the topological features of the flow near the recessed nozzle and the position of local maximums of the heat transfer coefficient. It has been revealed that The use of a channel with a star-shaped cross section and a triangular form of compensator rays leads to an intensification of heat exchange processes near a recessed nozzle.

scholarly journals HYDRODYNAMICS, DISTRIBUTION OF FLOWS AND THERMAL EFFICIENCY OF COIL HEAT EXCHANGERS IN UNITS OF HEAT-USING APPARATUS OF TUBE FURNACES

2019 ◽  
Vol 62 (4) ◽  
pp. 143-151
Author(s):  
Stanislav P. Sergeev ◽  
Faddey F. Nikiforov ◽  
Sergey V. Afanasiev ◽  
Juliya N. Shevchenko
Keyword(s):  
Heat Exchange ◽  
Turbulent Flow ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Heat Fluxes ◽  
Hydrodynamic Characteristics ◽  
Technological Problem ◽  
Tube Furnaces ◽  
Suction Or Injection ◽  
Coil Heat

The theoretical foundations of construction, mathematical description and engineering calculation of heat exchangers of the serpentine type in blocks of heat-using equipment of tube furnaces and other types of reactors designed for carrying out endothermic reactions (in particular, reforming of natural gas with water vapor) are considered. It is shown that the thermal efficiency of heat exchangers of the coil type is significantly affected by the correct choice of parameters ensuring a uniform distribution of energy flows over the surface of heat-resistant heat exchange tubes. This technological problem is solved by compiling the heat balance and selecting the system of the corresponding equations, which allows to calculate the temperature contour of the coil heat exchanger, its hydrodynamic characteristics and the distribution of mass and heat flows through the heat exchange tubes. The use of the tensor form of the Boussinesq hypothesis is considered, with which the Reynolds equation describing a turbulent flow is transformed to a partial differential equation for a single unknown function and its averaged form is obtained. In relation to the problem under consideration, the correctness of the chosen approach was confirmed both theoretically and experimentally. It is shown that in the core of a turbulent flow with an intense suction or injection, the liquid behaves almost as ideal and the well-known Helmholtz – Friedmann theorem holds with the necessary accuracy. From the aforementioned averaged equation, expressions are obtained that are suitable for describing heat fluxes in channels with suction or injection. According to this theoretical model, thermal calculations of coil-type heat exchangers were carried out, a more accurate assessment of the temperature of the heated medium in each coil tube was made, and the temperature gradient of the external heat carrier over the cross section of the gas duct was found. For the first time in the practice of calculations when choosing the parameters of coils, a number of boundary conditions were taken into account, such as the condition of the coil layout, the necessary heat exchange surface, permissible restrictions on hydraulic resistance, etc.

scholarly journals A Three-Dimensional, Time-Dependent Circulation Model of Utah Lake

2009 ◽  
Author(s):  
Robert E. Spall ◽  
Brandon Wilson ◽  
Eric Callister
Keyword(s):  
Thermal Stratification ◽  
Three Dimensional ◽  
Circulation Model ◽  
Short Wave ◽  
Heat Fluxes ◽  
Environmental Forcing ◽  
Temperature Distributions ◽  
Northern Utah ◽  
Wind Events ◽  
Utah Lake

The thermal behavior of Utah Lake, situated in northern Utah, is modeled over a spring-to-fall period using environmental forcing data from the year 2007. Results compare favorably with previously obtained data for temperature distributions around the lake during midsummer 2007. During the spring months, when experimental data is not available, the model predicts strong and rapid variations in the water temperature, which correlate well with significant storms on the lake. A heat balance shows that the largest components of heat fluxes into and out of the lake are due to short wave solar and evaporative cooling, respectively. Both numerical and experimental results also indicate that, due to the shallow nature of the lake and occurrence of significant wind events, thermal stratification is never achieved.

Numerical Simulation on Fouling of the Steam Cooler in a Power Plant

2013 ◽  
Vol 291-294 ◽  
pp. 1969-1974
Author(s):  
Wei Liang Cheng ◽  
An Di ◽  
Li Chao Liu ◽  
Lian Guang Liu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchange ◽  
Power Plant ◽  
Power Plants ◽  
Engineering Application ◽  
Flow State ◽  
Equipment Safety ◽  
Heat Exchange Tube ◽  
Reasonable Model

The fouling in the heat transfer devices of power plants, not only changes the fluid flow state designed, but also counteracts the heat transfer, so the equipment safety and economy are reduced. The adsorption and deposition about fouling is a quite complicated chemical and physical process, and it is difficult to obtain an accurate and reasonable model and its engineering application. Therefore, under some different conditions such as velocity, temperature and concentration of fouling and pipe position, the numerical simulation is obtained in the power plant steam cooler. The temperature inside the pipe is gradually decreased with the velocity. At the same time, the fouling increases in the first half of the exchanger pipe, and easily appears near regions of entrance more and more. The fouling may occurs at the outlet position of the heat exchange tube. Under the same conditions the heat exchange tube near centre line is easier to bring the fouling.

scholarly journals Analogy in the processes of heat exchange of capillary-porous coatings in energy installations

2019 ◽  
Vol 85 ◽  
pp. 05003
Author(s):  
Alexander Genbach ◽  
David Bondartsev ◽  
Iliya Iliev ◽  
Angel Terziev
Keyword(s):  
Heat Exchange ◽  
High Heat ◽  
Heat Fluxes ◽  
Porous Coating ◽  
Heat Conducting ◽  
Porous System ◽  
Experimental Conditions ◽  
Limiting State ◽  
Combined Action ◽  
System Operating

A model of the dynamics of steam bubbles generating on a solid surface in porous structures and a steam-generating wall (substrate) is developed. The model is based on the filming and photography with speed camera SKS-1M. The removal of high heat fluxes (up to 2х106 W/m2) is provided by the combined action of capillary and mass forces with application of intensifiers. An analytical model is developed based on the theory of thermoelasticity. The limiting state of a poorly heat-conducting porous coating and a metal substrate has been determined. The heat fluxes were calculated from the time of spontaneous appearance of the steam nucleation (10-8) up to the time of material destruction (102 ÷ 103 s). The destruction of the coating under the action of compression forces occurs in much earlier time than the tension forces. The intervals of the heat flux within which such destruction occurs are different for the quartz coating qmax ≈ 7х107 W/m2, qmin ≈ 8х104 W/m2 and for granite coating qmax ≈ 1х107 W/m2, qmin ≈ 21х104 W/m2. Experimental units, experimental conditions, the results of the heat exchange crisis and the limiting state of the surface are presented, and critical heat fluxes are calculated. The investigated capillary-porous system, operating under the combined action of capillary and mass forces, has the advantage over pool boiling, thin-film evaporators and heat pipes.

Sign in / Sign up

Export Citation Format

Share Document