Research on Simulation of Operation of DSG Collectors Based on Analysis of Scientific Materials

2011 ◽  
Vol 282-283 ◽  
pp. 710-715 ◽  
Author(s):  
Teng Gao ◽  
Jun Zhao ◽  
Bin Yang ◽  
Fu Wang
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Energy Balance Equation ◽  
Basic Program ◽  
Transfer Model ◽  
Fluid Temperature ◽  
Steam Generation ◽  
Collector Efficiency ◽  
Steady State Heat Transfer ◽  
Fluid Parameters

In this paper, a direct steam generation (DSG) collector is researched. To determinate the DSG collector efficiency, a simplified heat loss correlation is applied. A one-dimensional steady state heat transfer model and an energy balance equation for DSG collector are developed. A Visual basic program coupled with fluid parameters is compiled to compute fluid temperature, heat transfer coefficient and heat loss along the absorber tube by iterations for given accuracy. The variation trends of many kinds of fluid parameters along the absorber tube are revealed. The effect of length of dry steam region on collector efficiency is accounted for also.

scholarly journals Safe Duration Of A Person Soaking Inside A Hot Tub: Theoretical Prediction of Temperature Elevations in Human Bodies Using A Whole Body Heat Transfer Model

2020 ◽  
Author(s):  
Myo Min Zaw ◽  
Manpreet Singh ◽  
Ronghui Ma ◽  
Liang Zhu
Keyword(s):  
Heat Transfer ◽  
Human Body ◽  
Energy Balance Equation ◽  
The Body ◽  
Whole Body ◽  
Equation Modeling ◽  
Transient Temperature ◽  
Transfer Model ◽  
Bioheat Equation ◽  
Arterial Blood

In this study, we first develop a whole body model based on measurements of a human body, with realistic boundary conditions incorporated before and after a person jumps into a hot tub. For the transient heat transfer simulation, the initial condition is the established steady state temperature field of the human body with appropriate clothing layer to ensure the thermal equilibrium of the body with its surroundings. Once the person is inside a hot tub, the Pennes bioheat equation is used to simulate the transient temperature elevations of the body, and the rising of the arterial blood temperature is solved by an energy balance equation modeling thermal exchange between body tissue and the blood in the body. The safe duration of soaking in hot tubs is then determined as affected by the hot tub water temperatures.

scholarly journals Nonuniform Heat Transfer Model and Performance of Molten Salt Cavity Receiver

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1001
Author(s):  
Jianfeng Lu ◽  
Yarong Wang ◽  
Jing Ding
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Thermal Efficiency ◽  
Radiation Flux ◽  
Incident Radiation ◽  
Heat Transfer Model ◽  
Experimental Result ◽  
Transfer Model ◽  
Fluid Temperature ◽  
Primary Role

The temperature distribution and thermal efficiency of a molten salt cavity receiver are investigated by a nonuniform heat transfer model based on thermal resistance analysis. For the cavity receiver MSEE in Sandia National Laboratories, thermal efficiency in this experiment is about 87.5%, and the calculation value of 86.93–87.79% by a present nonuniform model fits very well with the experimental result. Different from the uniform heat transfer model, the receiver surface temperature in the nonuniform heat transfer model is remarkably higher than the backwall temperature. The incident radiation flux plays a primary role in thermal performance of cavity receiver, and thermal efficiency approaches to maximum under optimal incident radiation flux. In order to increase thermal efficiency, various methods are proposed and studied, including heat convection enhancement by an increase of flow velocity or the decrease of the tube diameter and number of tubes in the panel, and heat loss decline by a decrease of view factor, surface emissivity and insulation conductivity. According to calculation results by different modes of the nonuniform heat transfer model, the thermal efficiency of the cavity receiver is reduced by nonuniform heat transfer caused by variable fluid temperature or variable circumferential temperature, so thermal efficiency calculated by variable fluid temperature and variable circumferential temperature is lower than that calculated by average fluid temperature and bilateral uniform circumferential temperature for 0.86%.

scholarly journals Heat transfer in a low latitude flat-plate solar collector

2012 ◽  
Vol 16 (2) ◽  
pp. 583-591
Author(s):  
C.O.C. Oko ◽  
S.N. Nnamchi
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Solar Collector ◽  
Design Parameters ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Port Harcourt ◽  
Collector Efficiency ◽  
One Year ◽  
Flat Plate Solar Collector

Study of rate of heat transfer in a flat-plate solar collector is the main subject of this paper. Measurements of collector and working fluid temperatures were carried out for one year covering the harmattan and rainy seasons in Port Harcourt, Nigeria, which is situated at the latitude of 4.858oN and longitude of 8.372oE. Energy balance equations for heat exchanger were employed to develop a mathematical model which relates the working fluid temperature with the vital collector geometric and physical design parameters. The exit fluid temperature was used to compute the rate of heat transfer to the working fluid and the efficiency of the transfer. The optimum fluid temperatures obtained for the harmattan, rainy and yearly (or combined) seasons were: 317.4, 314.9 and 316.2 [K], respectively. The corresponding insolation utilized were: 83.23, 76.61 and 79.92 [W/m2], respectively, with the corresponding mean collector efficiency of 0.190, 0.205 and 0.197 [-], respectively. The working fluid flowrate, the collector length and the range of time that gave rise to maximum results were: 0.0093 [kg/s], 2.0 [m] and 12PM - 13.00PM, respectively. There was good agreement between the computed and the measured working fluid temperatures. The results obtained are useful for the optimal design of the solar collector and its operations.

A Semi-Empirical Heat Transfer Model for Forced Convection in Pin-Fin Heat Sinks Subjected to Nonuniform Heating

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
S. S. Feng ◽  
T. Kim ◽  
T. J. Lu
Keyword(s):  
Heat Transfer ◽  
Substrate Temperature ◽  
Analytical Model ◽  
Heat Sinks ◽  
Nonuniform Heating ◽  
Transfer Model ◽  
Substrate Thickness ◽  
Fluid Temperature ◽  
Pin Fin ◽  
Semi Empirical

This paper presents a cost effective semi-empirical analytical model for convective heat transfer in pin-fin heat sinks subjected to nonuniform heating set by a circular hot gas impinging jet. Based on empirical correlations taken from the open literature, temperature variations in the heat sink are obtained from the finite volume solution of the semi-empirical model. Based on a purpose-built experimental setup, measurements of a substrate temperature are performed using an infrared camera. These, along with the convective fluid temperature measured at the exit of the pin-fin array, are compared against analytical model predictions, with overall good agreement achieved. Subsequently, the influences of the convection Reynolds number, substrate thickness, and thermal conductivity of material on the distribution of substrate temperature are quantified by the validated model. It is demonstrated that the present model is capable of predicting local thermal behaviors such as the footprints of the pin fins. In addition, with the spreading resistance captured accurately, the model can be used for the design optimization of pin-fin/substrate systems subjected to nonuniform heating.

Heat Transfer in the Non-reacting Zone of a Cement Rotary Kiln

1996 ◽  
Vol 118 (1) ◽  
pp. 169-172 ◽  
Author(s):  
P. S. Ghoshdastidar ◽  
V. K. Anandan Unni
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Rotary Kiln ◽  
Gas Flow ◽  
Transfer Model ◽  
Temperature Profiles ◽  
Gas Temperature ◽  
Gas Flow Rate ◽  
Steady State Heat ◽  
Steady State Heat Transfer

This paper presents a steady-state heat transfer model for a rotary kiln used for drying and preheating of wet solids with application to the non-reacting zone of a cement rotary kiln. A detailed parametric study indicates that the influence of the controlling parameters such as percent water content (with respect to dry solids), solids flow rate, gas flow rate, kiln inclination angle and the rotational speed of the kiln on the axial solids and gas temperature profiles and the total predicted kiln length is appreciable.

The effect of heat loss on the performance of a solar-driven heat engine

2009 ◽  
Vol 223 (7) ◽  
pp. 1615-1621
Author(s):  
O S Sogut ◽  
A Durmayaz
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Loss ◽  
Transfer Process ◽  
Rankine Cycle ◽  
Heat Transfer Process ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Parabolic Trough ◽  
Thermal Reservoir

An optimal performance analysis of a parabolic-trough direct-steam-generation solar-driven Rankine cycle power plant at maximum power (MP) and under maximum power density (MPD) conditions is performed numerically to investigate the effects of heat loss from the heat source and working fluid. In this study, the ideal Rankine cycle of the solar-driven power plant is modified into an equivalent Carnot-like cycle with a finite-rate heat transfer. The main assumptions of this study include that: (a) the parabolic collector is the thermal reservoir at a high temperature, (b) the heat transfer process between the collector and the working fluid is through either radiation and convection simultaneously or radiation only, and (c) the heat transfer process from the working fluid to the low-temperature thermal reservoir is convection dominated. Comprehensive discussions on the effect of heat loss during the heat transfer process from the hot thermal reservoir to the working fluid in the parabolic-trough solar collector are provided. The major results of this study can be summarized as follows: (a) the working fluid temperature at the hot-side heat exchanger decreases remarkably whereas the working fluid temperature at the cold-side heat exchanger does not show any significant change with increasing heat loss, (b) the MP, MPD, and thermal efficiencies decrease with increasing heat loss, and (c) the effect of heat loss on the decrease of thermal efficiency increases when convection is the dominant heat transfer mode at the hot-side heat exchanger.

Heat Transfer and Thermal Balance Analysis of an Aluminum Electrolysis Cell Side Lines: A Heat Recovery Capability and Feasibility Study

2013 ◽  
Author(s):  
Yaser Mollaei Barzi ◽  
Mohsen Assadi
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Heat Recovery ◽  
Side Wall ◽  
Operating Conditions ◽  
Energy Utilization ◽  
Heat Extraction ◽  
Electrolysis Cell ◽  
Transfer Model ◽  
Side Walls

In this study, a preliminary investigation is carried out concerning the possibility and feasibility of recovering part of the side walls heat loss to use it in an energy utilization system. For this purpose, a simple smart heat transfer model is developed for the aluminum smelter side lines accounting for the dynamic ledge profile variations and phase change. Using the model, the total side wall heat loss is estimated and evaluated in different operating conditions of the cell. The system flexibility and self-adjustment ability are taken in to account to find the appropriate solution for the heat extraction system. Using the above-mentioned analysis, the heat recovery strategy and also the possible and applicable alternatives for the side walls heat collection and utilization system are investigated.

Boundary Design of Reflection Properties of a Steady-State Complex Heat Transfer Model

2016 ◽  
Vol 685 ◽  
pp. 90-93
Author(s):  
Alexander Yu. Chebotarev ◽  
Andrey E. Kovtanyuk
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Control Problem ◽  
Radiation Effects ◽  
Heat Transfer Model ◽  
Heat Radiation ◽  
Transfer Model ◽  
Multiplicative Control ◽  
Steady State Heat ◽  
Steady State Heat Transfer

A boundary multiplicative control problem for a nonlinear steady-state heat transfer model accounting for heat radiation effects is considered. The aim of control consists in obtaining a prescribed temperature or radiative intensity distributions in a part of the model domain by controlling the boundary reflectivity. The solvability of this control problem is proved, and optimality conditions are derived.

Sign in / Sign up

Export Citation Format

Share Document