scholarly journals Evaluation of simultaneous effects of inlet stagnation pressure and heat transfer on condensing water-vapor flow in a supersonic Laval nozzle

2013 ◽  
Vol 20 (1) ◽  
pp. 141-151 ◽  
Author(s):  
E. Amiri Rad ◽  
M.R. Mahpeykar ◽  
A.R. Teymourtash
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Laval Nozzle ◽  
Stagnation Pressure ◽  
Vapor Flow

scholarly journals An Experimental Investigation of Water Vapor Condensation from Biofuel Flue Gas in a Model of Condenser, (1) Base Case: Local Heat Transfer without Water Injection

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 844
Author(s):  
Robertas Poškas ◽  
Arūnas Sirvydas ◽  
Vladislavas Kulkovas ◽  
Povilas Poškas
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Flue Gas ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Water Injection ◽  
Vapor Condensation ◽  
Base Case ◽  
Water Vapor Condensation ◽  
Condensing Heat Exchanger

Waste heat recovery from flue gas based on water vapor condensation is an important issue as the waste heat recovery significantly increases the efficiency of the thermal power units. General principles for designing of this type of heat exchangers are known rather well; however, investigations of the local characteristics necessary for the optimization of those heat exchangers are very limited. Investigations of water vapor condensation from biofuel flue gas in the model of a vertical condensing heat exchanger were performed without and with water injection into a calorimetric tube. During the base-case investigations, no water was injected into the calorimetric tube. The results showed that the humidity and the temperature of inlet flue gas have a significant effect on the local and average heat transfer. For some regimes, the initial part of the condensing heat exchanger was not effective in terms of heat transfer because there the flue gas was cooled by convection until its temperature reached the dew point temperature. The results also showed that, at higher Reynolds numbers, there was an increase in the length of the convection prevailing region. After that region, a sudden increase was observed in heat transfer due to water vapor condensation.

Heat transfer intensification by increasing vapor flow rate in flat heat pipes

2015 ◽  
Author(s):  
Silviu Sprinceana ◽  
Ioan Mihai ◽  
Marius Beniuga ◽  
Cornel Suciu
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Pipes ◽  
Vapor Flow ◽  
Heat Transfer Intensification

scholarly journals Comparative Modeling of a Parabolic Trough Collectors Solar Power Plant with MARS Models

Energies ◽  
2017 ◽  
Vol 11 (1) ◽  
pp. 37 ◽  
Author(s):  
Jose Rogada ◽  
Lourdes Barcia ◽  
Juan Martinez ◽  
Mario Menendez ◽  
Francisco de Cos Juez
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Power Plant ◽  
Solar Radiation ◽  
Thermal Energy ◽  
Power Plants ◽  
Solar Power ◽  
Rankine Cycle ◽  
Heat Transfer Fluid ◽  
Solar Field

Power plants producing energy through solar fields use a heat transfer fluid that lends itself to be influenced and changed by different variables. In solar power plants, a heat transfer fluid (HTF) is used to transfer the thermal energy of solar radiation through parabolic collectors to a water vapor Rankine cycle. In this way, a turbine is driven that produces electricity when coupled to an electric generator. These plants have a heat transfer system that converts the solar radiation into heat through a HTF, and transfers that thermal energy to the water vapor heat exchangers. The best possible performance in the Rankine cycle, and therefore in the thermal plant, is obtained when the HTF reaches its maximum temperature when leaving the solar field (SF). In addition, it is necessary that the HTF does not exceed its own maximum operating temperature, above which it degrades. The optimum temperature of the HTF is difficult to obtain, since the working conditions of the plant can change abruptly from moment to moment. Guaranteeing that this HTF operates at its optimal temperature to produce electricity through a Rankine cycle is a priority. The oil flowing through the solar field has the disadvantage of having a thermal limit. Therefore, this research focuses on trying to make sure that this fluid comes out of the solar field with the highest possible temperature. Modeling using data mining is revealed as an important tool for forecasting the performance of this kind of power plant. The purpose of this document is to provide a model that can be used to optimize the temperature control of the fluid without interfering with the normal operation of the plant. The results obtained with this model should be necessarily contrasted with those obtained in a real plant. Initially, we compare the PID (proportional–integral–derivative) models used in previous studies for the optimization of this type of plant with modeling using the multivariate adaptive regression splines (MARS) model.

The Study on Flow Patterns of Condensation of Superheated Vapor in Nanochannels

2010 ◽  
Author(s):  
Hualing Zhang ◽  
Liu Chao
Keyword(s):  
Water Vapor ◽  
Flow Patterns ◽  
Vapor Condensation ◽  
Condensation Process ◽  
Vapor Flow ◽  
Bubble Flow ◽  
Superheated Water ◽  
Injection Flow ◽  
Two Phases ◽  
Solid Walls

The model of two phases of liquid and vapor flow and vapor condensation under the condition of exerted force was established in parallel nanochannel. Fluid was water molecular and the solid walls are composed of Pt atoms. The process of vapor condensation in nanochannel wall was simulated by molecular dynamic simulation. The different flow patterns of the condensation process of superheated water vapor, which mainly were annular flow, injection flow, slug flow, bubble flow and shrinking bubble flow, were observed under different conditions. For low pressure of water vapor, a new flow pattern which was named as fluctuation flow appeared during condensation process. The simulation results agreed very well with the experimental results provided by references.

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