Hydrodynamic Analysis of Direct Steam Generation Solar Collectors

1999 ◽  
Vol 122 (1) ◽  
pp. 14-22 ◽  
Author(s):  
S. D. Odeh ◽  
M. Behnia ◽  
G. L. Morrison
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Operating Conditions ◽  
Tube Length ◽  
Solar Collectors ◽  
Flow Conditions ◽  
Steam Generation ◽  
Frictional Pressure Drop ◽  
Wide Range ◽  
Direct Steam

Direct steam generation collectors are considered with the aim to improve the performance of a parabolic trough collector leading to a reduction of operating costs of solar electric generation systems. In this study a hydrodynamic steady state model is developed and linked with a thermal model to optimize the performance of once-through direct steam generation solar collectors. The hydrodynamic model includes flow pattern classification and a pressure drop model. Flow pattern maps for typical DSG collectors with horizontal and inclined absorber tubes are generated to investigate the variation of flow conditions with radiation level, tube diameter, tube length and flow rate. Two-phase flow frictional pressure drop correlations for the range of operating conditions in a DSG collector are selected from the wide range of published correlations by comparison with experimental data for typical steam-water flow conditions in a DSG collector. Pressure drop is calculated for different operating conditions for both horizontal and inclined solar absorber tubes. Alternative operational strategies are evaluated to achieve optimum performance of a direct steam generation collector at different radiation levels. [S0199-6231(00)00101-5]

An Experimental Investigation of Pressure Drop During Partial Condensation of Low Pressure Steam

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Jacques du Plessis ◽  
Michael Owen
Keyword(s):  
Pressure Drop ◽  
Cooling System ◽  
Thermal Power ◽  
Steam Pressure ◽  
Tube Length ◽  
Condenser Tube ◽  
Cooling Systems ◽  
Frictional Pressure Drop ◽  
Wide Range ◽  
Experimental Apparatus

Abstract As direct dry-cooling systems are becoming more popular for thermal power plants, there is a demand to increase the flexibility of the application and performance of these cooling systems. A novel hybrid (dry/wet) dephlegmator (HDWD) cooling system is being developed, and at this stage in the development of the HDWD, the performance analysis and optimization of the HDWD is currently subject to uncertainties in a number of parameters. One of the parameters is the confidence in the correlations to predict the steam-side pressure drop over the wide range of full to partial condensation conditions expected in the system as a result of the design. This study makes use of an experimental apparatus to measure steam pressure drop over a range of partial to full condensation inside a circular horizontal tube. The experiment is conducted by measuring the steam flow and steam pressure drop in a horizontal primary condenser tube with the presence of a secondary condenser tube. The primary condenser has a tube length of 2.5 m and an inside tube diameter of 19.3 mm similar to the proposed HDWD design. Existing correlations for pressure drop in condensing flow are compared with the results to assess the applicability of the correlations for the HDWD case. It was found that the correlation of Lockhart and Martinelli’s with the Chisholm parameter fits the experimental data the best with a mean error of ±15.6%. A parametric study also indicated that there is a prominent increase in the frictional pressure drop at low partial condensation ratios (i.e., high steam through flow) as expected with wave drag at the vapor and condensate interface due to the difference in velocity.

scholarly journals A Direct-Steam Linear Fresnel Performance Model for NREL’S System Advisor Model

2012 ◽  
Author(s):  
Michael J. Wagner ◽  
Guangdong Zhu
Keyword(s):  
Heat Loss ◽  
Mathematical Formulation ◽  
Model Performance ◽  
Performance Model ◽  
Electricity Production ◽  
Steam Generation ◽  
Time Step ◽  
Wide Range ◽  
Direct Steam ◽  
Solar Field

This paper presents the technical formulation and demonstrated model performance results of a new direct-steam-generation (DSG) model in NREL’s System Advisor Model (SAM). The model predicts the annual electricity production of a wide range of system configurations within the DSG Linear Fresnel technology by modeling hourly performance of the plant in detail. The quasi-steady-state formulation allows users to investigate energy and mass flows, operating temperatures, and pressure drops for geometries and solar field configurations of interest. The model includes tools for heat loss calculation using either empirical polynomial heat loss curves as a function of steam temperature, ambient temperature, and wind velocity, or a detailed evacuated tube receiver heat loss model. Thermal losses are evaluated using a computationally efficient nodal approach, where the solar field and headers are discretized into multiple nodes where heat losses, thermal inertia, steam conditions (including pressure, temperature, enthalpy, etc.) are individually evaluated during each time step of the simulation. This paper discusses the mathematical formulation for the solar field model and describes how the solar field is integrated with the other subsystem models, including the power cycle and optional auxiliary fossil system. Model results are also presented to demonstrate plant behavior in the various operating modes.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

Experimental Investigation on Flow Patterns and Frictional Pressure Drop of Downward Air-Water Two-Phase Flow in Vertical Pipes

2013 ◽  
Author(s):  
Yuqing Xue ◽  
Huixiong Li ◽  
Tianyou Sheng ◽  
Changjiang Liao
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Oil Recovery ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Vertical Pipe ◽  
Two Phase Flows ◽  
Two Phase ◽  
Frictional Pressure Drop

A large amount of air need be transported into the reservoir in the deep stratum to supply oxygen to some microbes in Microbial Enhanced Oil Recovery (MEOR). Air-water two-phase flows downward along vertical pipeline during the air transportation. Base on the experiment data described in this paper, the characteristics of air-water two phase flow patterns were investigated. The flow pattern map of air-water two phase flows in the pipe with inner diameter of 65 mm was drawn, criterions of flow pattern transition were discussed, and the dynamic signals of the pressure and the differential pressure of the two phase flow were recorded to characterize the three basic flow regimes indirectly. The frictional pressure drop of downward flow in vertical pipe must not be disregarded contrast with upward two phase flow in the vertical pipe because the buoyancy must be overcame when the gas flows downward along pipe, and there would be a maximum value of frictional when the flow pattern translated from slug flow to churn flow.

A Flow Model for Two-Phase Slug Flow in Horizontal Tubes

1961 ◽  
Vol 83 (4) ◽  
pp. 613-618 ◽  
Author(s):  
E. S. Kordyban
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Slug Flow ◽  
Flow Model ◽  
Simplified Model ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Horizontal Tubes

The paper presents a construction of a simplified model approximating the actual observed flow pattern. The resulting expressions for frictional pressure drop are found to agree fairly well with the author’s data for steam and water and the data for air and water of other investigators. The similarity with a portion of the Chenoweth-Martin correlation appears to present a logical explanation for the applicability of that correlation to slug flow.

Evaluation of Frictional Pressure Drop Correlations During Flow Boiling of Refrigerants in Micro-Fin Tubes

2020 ◽  
Author(s):  
Weiyu Tang ◽  
Wei Li ◽  
Jianxin Zhou
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Predictive Ability ◽  
Operating Conditions ◽  
Commercial Application ◽  
Equivalent Diameter ◽  
Specific Work ◽  
Frictional Pressure Drop ◽  
Data Points ◽  
Fin Tubes

Abstract Due to the widely commercial application of micro-fin tube and eco-friendly refrigerants, more general frictional pressure drop correlations is demanded for better prediction, and this study is aimed at compared existing correlations and provide guides for the furthermore improvement. Experimental data points for frictional pressure drop during flow boiling of refrigerants in horizontal micro-fin tubes were extracted from literature and our previous experimental work to evaluate numerous existing frictional pressure drop correlations and specify their applicability to meet the urgent demand of extensive application of eco-friendly refrigerants. The database consists of 949 data points covering eleven refrigerants (R1233zd(Z), R410A, R1234ze(E), R410A, R22, R32, R1234ze(Z), R22, R134a, R245fa and R1234yf included), and the involved operation conditions are as follows: mass velocity 94–888 kg m−2s−1, vapor quality 0.04–0.99, heat flux 3.9–85.2 kW m−2, and equivalent diameter 2.12–11.84mm. Eight existing general frictional pressure drop correlation including Cavallini et al., Kuo and Wang, Wongsangam et al. and Rollman and Spindler correlation were evaluated against the present database. In addition, the Churchill et al. model was employed in several correlation to improve their performance. It was found that none of these correlations was capable of providing a satisfactory prediction for a general operation condition. A detailed predictive ability of these correlation against specific work fluids were given for reference, and their individual parametric-trend predictive ability were also compared under varied operating conditions using several datasets.

Experimental Study of Thermal Performance and Pressure Drop in Compact Heat Exchanger Installed in Automotive

2006 ◽  
Author(s):  
M. H. Saidi ◽  
A. A. Mozafari ◽  
A. R. Esmaeili Sany ◽  
J. Neyestani
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Operating Conditions ◽  
Design Stage ◽  
Practical Usefulness ◽  
Experimental Prediction ◽  
Wide Range

In this Study, radiator performance for passenger car has been studied experimentally in wide range of operating conditions. Experimental prediction of Nusselt number and heat transfer coefficient for coolant in radiator tubes are also performed with ε–NTU method. The total effectiveness coefficient of radiator and heat transfer coefficient in air side is calculated via try and error method considering experimental data. The Colburn factor and pressure drop are also estimated for this heat exchanger. Examples of application demonstrate the practical usefulness of this method to provide empirical data which can be used during the design stage.

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