On the Hydrodynamic Analysis and Heat Transfer Investigation of Forced Oscillated Vertical Annular Fluid Column

2016 ◽  
Author(s):  
Ersin Sayar
Keyword(s):  
Heat Transfer ◽  
Energy Balance ◽  
Water Column ◽  
Control Volume ◽  
Heat Convection ◽  
Measured Temperature ◽  
Cycle Space ◽  
Oscillating Flows ◽  
Radial Temperature ◽  
Hydrodynamic Analysis

Heat transfer from a forced oscillated water column is investigated experimentally and theoretically. Further details of the water flow can be given as mini-scale, vertical, annular, internal, reciprocating and single phase. The inner wall of the stationary concentric element is heated and water is oscillated through the annuli. The data is acquired from the measurements both in the initial transient period and in the pseudo-steady (cyclic) period from the experimental set-up. The effect of the oscillations is observed on the measured temperature field and heat transfer. There is minor radial temperature variation in the water column. Experimental study proved that the frequency, wall heat flux and related wall temperatures are important parameters affecting heat transfer. It is understood that, the effective heat transfer mechanism is enhanced in oscillating flows. Cycle and space-averaged heat convection coefficients are calculated for the present oscillating flows. The physical and mathematical behavior of the resulting heat convection coefficients are analyzed using the data acquired from the experiments. The predicted cycle-space averaged heat convection coefficients using the experimental data are shown to have a logical trend with the experimental observations. The analysis is carried out for different oscillation frequencies at various applied wall heat fluxes while the displacement amplitude remains constant. A novel control volume formulation is introduced in order to investigate pressure distribution and energy balance of water over a cycle for the present reciprocating flow and the formulations are reorganized in order to capture the cycle-averaged energy balance of the control volume. The present study is novel because it appears to be the first paper on the analytical hydrodynamic analysis of forced oscillated vertical annular fluid flow. The present investigation has possible applications in moderate sized wicked heat pipes, solid matrix compact heat exchangers compromising of metallic foams (in some other types of heat exchengers as well), possibly in boilers, filtration equipment, and steam generators.

scholarly journals CFD simulation of forced heat transfer of gas in pipe

2019 ◽  
Vol 112 ◽  
pp. 01008 ◽  
Author(s):  
Zhivko Kolev ◽  
Seher Kadirova
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Cfd Simulation ◽  
Geometric Model ◽  
Internal Surface ◽  
Heat Convection ◽  
Steel Pipe ◽  
Measured Temperature ◽  
Simulation Methodology ◽  
Transfer Processes

This paper presents results from CFD simulation of heat transfer processes in ABAQUS. The investigations are realized at forced convection of air in steel pipe. Verification of the computing mesh and validation of the model, have been done. The average heat convection coefficients have been determined by methodology based on criteria equations, and on simulation methodology. Heat transfer processes between air flow in a steel pipe and the environment, have been experimentally accomplished. In order to analyze the processes of heat convection between the fluid and the internal surface of the pipe, numerical modelling is applied. A geometric model of the fluid flowing in the pipe is built. The computing mesh has been verified by increasing the number of cells and nodes. The numerical model has been validated based on experimentally measured temperature values and the simulation data. The heat convection coefficients have been investigated by analogy of the above. The results demonstrate that the numerical model is adequate and can be used to study similar heat transfer processes.

Characteristics of Heat Transfer During Machining With Rotary Tools

2004 ◽  
Vol 126 (2) ◽  
pp. 404-407 ◽  
Author(s):  
H. A. Kishawy and ◽  
A. G. Gerber
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Rotational Speed ◽  
Measured Temperature ◽  
Tool Rotational Speed ◽  
Radial Temperature ◽  
Conservation Of Energy ◽  
Finite Volume Discretization ◽  
Heat Partitioning ◽  
Good Agreement

In this paper a model is developed to analyze heat transfer and temperature distribution resulting during machining with rotary tools. The presented model is based on a finite-volume discretization approach applied to a general conservation of energy statement for the rotary tool and chip during machining. The tool rotational speed is modeled and its effect on the heat partitioning between the tool and the chip is investigated. The model is also used to examine the influence of tool speed on the radial temperature distribution on the tool rake face. A comparison between the predicted and previously measured temperature data shows good agreement. In general the results show that the tool-chip partitioning is influenced dramatically by increasing the tool rotational speed at low to moderate levels of tool speed. Also, there is an optimum tool rotational speed at which further increase in the tool rotational speed increases the average tool temperature.

Experimental and Computational Study of Flow and Heat Transfer Around a Surrogate Engine Mount

2017 ◽  
Author(s):  
Navni N. Verma ◽  
Andrei Iacob ◽  
Sandip Mazumder ◽  
Ahmet Selamet
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Control Volume ◽  
Catalytic Converter ◽  
Engine Block ◽  
Measured Temperature ◽  
Ansys Fluent ◽  
Flow And Heat Transfer ◽  
Close Proximity ◽  
Engine Mount

An experimental and computational investigation is conducted on the flow and heat transfer characteristics on and around a surrogate engine mount. The engine mount in an automobile is often in the close proximity of the catalytic converter, and may be subjected to considerable thermal radiation, combined with thermal conduction from the engine block through its bracket. The objective of this study is to develop a validated model that is capable of accurately predicting the temperature distribution on the mount. Two sets of heaters were implemented in the present study, both with controllable temperatures: band heaters to approximate the catalytic converter and cartridge heaters to represent the effect of the engine block at the bracket base. Carefully controlled experiments were first conducted with fixed heater temperatures, air flow rates, and bracket (at the base of the mount) temperatures. The temperatures were recorded at 22 different locations along the mount surface and the mount bracket for all input conditions. A computational fluid dynamics (CFD) model was next developed to simulate the same experiments. The simulations were conducted using roughly 5–6 million control volume (cells). The mesh was generated using ANSA™ and parallel computations of the governing equations were conducted using Ansys-Fluent™. For the broad matrix of cases considered, average predicted temperatures were found to agree with experimentally measured temperature to within 10°C (out of 300°C total variation), while local temperatures were found to agree within 10%.

Control of heat transfer in a geysering water column by ultrasound emission

2002 ◽  
Author(s):  
Hideo Kimoto ◽  
Takashi Fujii ◽  
Kenta Fujiwara
Keyword(s):  
Heat Transfer ◽  
Water Column

AN EXPERIMENTAL AND NUMERICAL STUDY OF HEAT TRANSFER IN A SIMULATED COLLECTOR FOR A SOLAR DRYER

1993 ◽  
Vol 17 (2) ◽  
pp. 145-160
Author(s):  
P.H. Oosthuizen ◽  
A. Sheriff
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Local Heat Transfer ◽  
Lower Surface ◽  
Local Heat ◽  
Electrical Heating ◽  
Temperature Profiles ◽  
Measured Temperature ◽  
Transfer Rates ◽  
Thermocouple Probe

Indirect passive solar crop dryers have the potential to considerably reduce the losses that presently occur during drying of some crops in many parts of the “developing” world. The performance so far achieved with such dryers has, however, not proved to be very satisfactory. If this performance is to be improved it is necessary to have an accurate computer model of such dryers to assist in their design. An important element is any dryer model is an accurate equation for the convective heat transfer in the collector. To assist in the development of such an equation, an experimental and numerical study of the collector heat transfer has been undertaken. In the experimental study, the collector was simulated by a 1m long by 1m wide channel with a gap of 4 cm between the upper and lower surfaces. The lower surface of the channel consisted of an aluminium plate with an electrical heating element, simulating the solar heating, bonded to its lower surface. Air was blown through this channel at a measured rate and the temperature profiles at various points along the channel were measured using a shielded thermocouple probe. Local heat transfer rates were then determined from these measured temperature profiles. In the numerical study, the parabolic forms of the governing equations were solved by a forward-marching finite difference procedure.

Oscillatory Heat Transfer in a Pipe Subjected to a Laminar Reciprocating Flow

1996 ◽  
Vol 118 (3) ◽  
pp. 592-597 ◽  
Author(s):  
T. S. Zhao ◽  
P. Cheng
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Nusselt Number ◽  
Numerical Study ◽  
Temperature Cycle ◽  
Uniform Heat Flux ◽  
Fluid Temperature ◽  
Cycle Space ◽  
Reciprocating Flow

An experimental and numerical study has been carried out for laminar forced convection in a long pipe heated by uniform heat flux and subjected to a reciprocating flow of air. Transient fluid temperature variations in the two mixing chambers connected to both ends of the heated section were measured. These measurements were used as the thermal boundary conditions for the numerical simulation of the hydrodynamically and thermally developing reciprocating flow in the heated pipe. The coupled governing equations for time-dependent convective heat transfer in the fluid flow and conduction in the wall of the heated tube were solved numerically. The numerical results for time-resolved centerline fuid temperature, cycle-averaged wall temperature, and the space-cycle averaged Nusselt number are shown to be in good agreement with the experimental data. Based on the experimental data, a correlation equation is obtained for the cycle-space averaged Nusselt number in terms of appropriate dimensionless parameters for a laminar reciprocating flow of air in a long pipe with constant heat flux.

A New Calculation Approach to the Energy Balance of a Gas Turbine Including a Study of the Impact of the Uncertainty of Measured Parameters

2005 ◽  
Author(s):  
Helmer G. Andersen ◽  
Pen-Chung Chen
Keyword(s):  
Energy Balance ◽  
Gas Turbine ◽  
Control Volume ◽  
Ambient Air ◽  
Energy Balance Equation ◽  
Inlet Temperature ◽  
Exhaust Gas ◽  
Gas Composition ◽  
Intake Flow ◽  
The Impact

Computing the solution to the energy balance around a gas turbine in order to calculate the intake mass flow and the turbine inlet temperature requires several iterations. This makes hand calculations very difficult and, depending on the software used, even causes significant calculation times on PCs. While this may not seem all that important considering the power of today’s personal computers, the approach described in this paper presents a new way of looking at the gas turbine process and the resulting simplifications in the calculations. This paper offers a new approach to compute the energy balance around a gas turbine. The energy balance requires that all energy flows going into and out of the control volume be accounted for. The difficulty of the energy balance equation around a gas turbine lies in the fact that the exhaust gas composition is unknown as long as the intake flow is unknown. Thus, a composition needs to be assumed when computing the exhaust gas enthalpy. This allows the calculation of the intake flow, which in turn provides a new exhaust gas composition, and so forth. By viewing the exhaust gas as a flow consisting of ambient air and combusted fuel, the described iteration can be avoided. The study presents the formulation of the energy balance applying this approach and looks at the accuracy of the result as a function of the inaccuracy of the input parameters. Furthermore, solutions of the energy balance are presented for various process scenarios, and the impact of the uncertainty of key process parameter is analyzed.

Analysis and Modelling of Temperature at Lake’s Water – Atmosphere Interface

2021 ◽  
Author(s):  
Vassilis Z. Antonopoulos ◽  
Soultana K. Gianniou
Keyword(s):  
Heat Transfer ◽  
Energy Balance ◽  
Surface Temperature ◽  
Water Surface ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Net Radiation ◽  
Water Surface Temperature ◽  
Simulation Results ◽  
Input Variables

Abstract The knowledge of micrometeorological conditions on water surface of impoundments is crucial for the better modeling of the temperature and water quality parameters distribution in the water body and against the climatic changes. Water temperature distribution is an important factor that affects most physical, chemical and biological processes and reactions occurring in lakes. In this work, different processes of water surface temperature of lake’s estimation based on the energy balance method are considered. The daily meteorological data and the simulation results of energy balance components from an integrated heat transfer model for two complete years as well as the lake’s characteristics for Vegoritis lake in northern Greece were used is this analysis.The simulation results of energy balance components from a heat transfer model are considered as the reference and more accurate procedure to estimate water surface temperature. These results are used to compare the other processes. The examined processes include a) models of heat storage changes in relationship to net radiation (Qt(Rn) values, b) net radiation estimation with different approaches, as the process of Slob’s equation with adjusted coefficients to lake data, and c) ANNs models with different architecture and input variables. The results show that the model of heat balance describes the water surface temperature with high accuracy (r2=0.916, RMSE=2.422oC). The ANN(5,6,1) model in which Tsw(i-1) is incorporated in the input variables was considered the better of all other ANN structures (r2=0.995, RMSE=0.490oC). The use of different approaches for simulating net radiation (Rn) and Qt(Rn) in the equation of water surface temperature gives results with lower accuracy.

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