Exergy Analysis of Condensation of a Binary Mixture With One Noncondensable Component in a Shell and Tube Condenser

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Y. Haseli ◽  
I. Dincer ◽  
G. F. Naterer
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Temperature Difference ◽  
Control Volume ◽  
Cooling Water ◽  
Exergy Efficiency ◽  
Numerical Results ◽  
Dimensionless Temperature ◽  
Condensation Process

The exergy (second-law) efficiency is formulated for a condensation process in a shell and one-path tube exchanger for a fixed control volume. The exergy efficiency ηex is expressed as a function of the inlet and outlet temperatures and mass flow rates of the streams. This analysis is utilized to assess the trend of local exergy efficiency along the condensation path and evaluate its value for the entire condenser, i.e., overall exergy efficiency. The numerical results for an industrial condenser, with a steam-air mixture and cooling water as working fluids, indicate that ηex is significantly affected by the inlet cooling water and environment temperatures. Further investigation shows that other performance parameters, such as the upstream mixture temperature, air mass flow rate, and ratio of cooling water mass flow rate to upstream steam mass flow rate, do not have considerable effects on ηex. The investigations involve a dimensionless ratio of the temperature difference of the cooling water and environment to the temperature difference of condensation and the environment. Numerical results for various operational conditions enable us to accurately correlate both the local and overall exergy efficiency as linear functions of dimensionless temperature.

scholarly journals Modeling and PSO optimization of Humidifier-Dehumidifier desalination

2018 ◽  
Vol 7 (1) ◽  
pp. 59 ◽  
Author(s):  
Mohammad Hossein Ahmadi ◽  
Mohammad Ali Afshar ◽  
Ali Naseri ◽  
Mokhtar Bidi ◽  
H. Hadiyanto
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Temperature Difference ◽  
Cooling Water ◽  
Decision Variable ◽  
Solar Air Heater ◽  
Air Heater ◽  
Output Ratio ◽  
Optimum Productivity

The aim of this study is modeling a solar-air heater humidification-dehumidification unit with applying particle swarm optimization to find out  the maximum gained output ratio with respect to the mass flow rate of water and air entering humidifier, mass flow rate of cooling water entering dehumidifier, width and length of solar air heater and terminal temperature difference (TTD) of dehumidifier representing temperature difference of inlet cooling water and saturated air to dehumidifier as its decision variable. A sensitivity analysis, furthermore, is performed to distinguish the effect of operating parameters including mass flow rate and streams’ temperature. The results showed that the optimum productivity decreases by decreasing the ratio of mass flow rate of water entering humidifier to air ones.Article History: Received: July 12th 2017; Revised: December 15th 2017; Accepted: 2nd February 2018; Available onlineHow to Cite This Article: Afshar, M.A., Naseri, A., Bidi, M., Ahmadi, M.H. and Hadiyanto, H. (2018) Modeling and PSO Optimization of Humidifier-Dehumidifier Desalination. International Journal of Renewable Energy Development, 7(1),59-64.https://doi.org/10.14710/ijred.7.1.59-64

Experimental Investigation of a Pilot Compression Chiller With Alternatives Refrigerants R401a and R134a

2005 ◽  
Author(s):  
M. Fatouh
Keyword(s):  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Cooling Water ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Chilled Water ◽  
Water Mass Flow Rate

This paper reports the results of an experimental investigation on a pilot compression chiller (4 kW cooling capacity) working with R401a and R134a as R12 alternatives. Experiments are conducted on a single-stage vapor compression refrigeration system using water as a secondary working fluid through both evaporator and condenser. Influences of cooling water mass flow rate (170–1900 kg/h), cooling water inlet temperature (27–43°C) and chilled water mass flow rate (240–1150 kg/h) on performance characteristics of chillers are evaluated for R401a, R134a and R12. Increasing cooling water mass flow rate or decreasing its inlet temperature causes the operating pressures and electric input power to reduce while the cooling capacity and coefficient of performance (COP) to increase. Pressure ratio is inversely proportional while actual loads and COP are directly proportional to chilled water mass flow rate. The effect of cooling water inlet temperature, on the system performance, is more significant than the effects of cooling and chilled water mass flow rates. Comparison between R12, R134a and R401a under identical operating conditions revealed that R401a can be used as a drop-in refrigerant to replace R12 in water-cooled chillers.

Selecting the cooling water mass flow rate for a power plant under variable load with entropy generation rate minimization

Energy ◽  
2016 ◽  
Vol 107 ◽  
pp. 725-733 ◽  
Author(s):  
Rafał Laskowski ◽  
Adam Smyk ◽  
Janusz Lewandowski ◽  
Artur Rusowicz ◽  
Andrzej Grzebielec
Keyword(s):  
Power Plant ◽  
Mass Flow Rate ◽  
Entropy Generation ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Cooling Water ◽  
Entropy Generation Rate ◽  
Variable Load ◽  
Water Mass Flow Rate

Numerical Investigation on the Heat Transfer Enhancement Behavior Outside Longitudinal Finned Tubes

2018 ◽  
Author(s):  
Yujia Zhou ◽  
Hanliang Bo ◽  
Jingyu Du
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Transfer Process ◽  
Numerical Results ◽  
Transfer Model ◽  
Hydraulic Characteristics ◽  
Finned Tubes ◽  
Smooth Tubes

With the purpose of enhancement of heat transfer performance and reduction of the volume of steam generator (SG), a structure of longitudinal finned tubes was proposed to replace the smooth tubes of SG in this paper. Taking the SG smooth tubes of Daya bay Nuclear Power plant as a reference, the simplified heat transfer model of new longitudinal finned tubes was established by ANSYS CFX. Three-dimensional numerical model was developed to investigate the fluid-solid coupled thermal hydraulic characteristics of different types of the longitudinal finned tubes compared with the smooth tubes. Analysis of calculation results were sufficiently discussed for the effect of mass flow rate, fin array, solid thermal conductivity and frictional resistance. The numerical results revealed that the heat transfer coefficient increase with the increasing mass flow rate in the secondary side. The material of the tubes has significantly influence on the heat transfer process. Different flow conditions have different thermal hydraulic characteristics. The evaluated criterion to judge the enhancement of the heat transfer of the coupled process was also proposed. The numerical results can provide some useful guidance for design optimization of longitudinal finned tubes in SG.

First and second thermodynamic law analyses applied to a solar dish collector

2014 ◽  
Vol 39 (4) ◽  
Author(s):  
Vahid Madadi ◽  
Touraj Tavakoli ◽  
Amir Rahimi
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Flow Rates ◽  
Energy And Exergy ◽  
Mass Flow Rates

AbstractThe energy and exergy performance of a parabolic dish collector is investigated experimentally and theoretically. The effect of receiver type, inlet temperature and mass flow rate of heat transfer fluid (HTF), receiver temperature, receiver aspect ratio and solar radiation are investigated. To evaluate the effect of the receiver aperture area on the system performance, three aperture diameters are considered. It is deduced that the fully opened receivers have the greatest exergy and thermal efficiency. The cylindrical receiver has greater energy and exergy efficiency than the conical one due to less exergy destruction. It is found that the highest exergy destruction is due to heat transfer between the sun and the receivers and counts for 35 % to 60 % of the total wasted exergy. For three selected receiver aperture diameters, the exergy efficiency is minimum for a specified HTF mass flow rate. High solar radiation allows the system to work at higher HTF inlet temperatures. To use this system in applications that need high temperatures, in cylindrical and conical receivers, the HTF mass flow rates lower than 0.05 and 0.09 kg/s are suggested, respectively. For applications that need higher amounts of energy content, higher HTF mass flow rates than the above mentioned values are recommended.

scholarly journals Efficiency Enhancement in Double-Pass Perforated Glazed Solar Air Heaters with Porous Beds: Taguchi-Artificial Neural Network Optimization and Cost–Benefit Analysis

2021 ◽  
Vol 13 (21) ◽  
pp. 11654
Author(s):  
Roozbeh Vaziri ◽  
Akeem Adeyemi Oladipo ◽  
Mohsen Sharifpur ◽  
Rani Taher ◽  
Mohammad Hossein Ahmadi ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Exergy Efficiency ◽  
Wire Mesh ◽  
Double Pass ◽  
Artificial Neural

Analyzing the combination of involving parameters impacting the efficiency of solar air heaters is an attractive research areas. In this study, cost-effective double-pass perforated glazed solar air heaters (SAHs) packed with wire mesh layers (DPGSAHM), and iron wools (DPGSAHI) were fabricated, tested and experimentally enhanced under different operating conditions. Forty-eight iron pieces of wool and fifteen steel wire mesh layers were located between the external plexiglass and internal glass, which is utilized as an absorber plate. The experimental outcomes show that the thermal efficiency enhances as the air mass flow rate increases for the range of 0.014–0.033 kg/s. The highest thermal efficiency gained by utilizing the hybrid optimized DPGSAHM and DPGSAHI was 94 and 97%, respectively. The exergy efficiency and temperature difference (∆T) indicated an inverse relationship with mass flow rate. When the DPGSAHM and DPGSAHI were optimized by the hybrid procedure and employing the Taguchi-artificial neural network, enhancements in the thermal efficiency by 1.25% and in exergy efficiency by 2.4% were delivered. The results show the average cost per kW (USD 0.028) of useful heat gained by the DPGSAHM and DPGSAHI to be relatively higher than some double-pass SAHs reported in the literature.

scholarly journals Exergy Analysis of Modified Solar Still

2015 ◽  
Vol 10 (2) ◽  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Brackish Water ◽  
Solar Collector ◽  
Exergy Analysis ◽  
Cooling Tower ◽  
Volume Flow Rate ◽  
Exergy Efficiency ◽  
Solar Still

A new design of solar still consist of flat plate solar collector, heat exchanger and cooling tower, was built and tested under Iraq weather at March. The still was tested under different mass flow rate of brackish water entering the flate plate solar collector, ranging from 0.01 to 0.015 kg/s. The volume flow rate of air through cooling tower was 0.0195 m3 /s. A full details of overall system as well as for system components exergy analysis were achieved. It was found that the maximum daily exergy efficiency of the still is less than 1%. While the maximum hourly exergy efficiency and maximum productivity for such combination were 3.46 kg/day and 1.6% , respectively, when the mass flow rate of brackish water was 0.013 kg/s.

scholarly journals Calculation of Rotor Dynamic Coefficients for Labyrinth Seals

1998 ◽  
Vol 4 (4) ◽  
pp. 257-269 ◽  
Author(s):  
B. P. Williams ◽  
R. D. Flack
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Control Volume ◽  
Small Variation ◽  
Design Tool ◽  
Pressure Drops ◽  
Dynamic Coefficients ◽  
Rotor Dynamic

A single control volume, Iwatsubo based bulk flow method for the calculation of these coefficients is developed and implemented. The method herein uses a unique iterative technique to first identify the mass flow rate based on pressure drops across the individual teeth, which is then used in the governing sets of continuity and momentum equations. The method is applicable to different teeth geometries and arrangements. A parametric analysis of the effect of mass flow rate on rotor dynamic coefficients is performed and suggests that a small variation in mass flow rate does not significantly detract from the accuracy of the predicted dynamic coefficients; the mass flow rate calculation implemented in this paper is sufficiently accurate. Furthermore, the inclusion of some tangential momentum parameters has been previously proposed to improve the accuracy of the Iwatsubo method. However, from the current analysis the inclusion of such parameters is also shown to have little effect on the rotor dynamic coefficients and does not lead to improved correlation with experimental data. Comparisons to experimental data suggest that the method herein is reasonable for use as a design tool to predict the trends and actual values of cross-coupled stiffness, the most important seal parameter in rotor dynamic analyses. The method is also shown to be useful in predicting the order of magnitude of principal stiffness and damping coefficients.

Experimental and Numerical Study of Cavitation in Centrifugal Pumps

2010 ◽  
Author(s):  
Erfan Niazi ◽  
M. J. Mahjoob ◽  
Ardeshir Bangian
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Mass Flow Rate ◽  
Computer Simulations ◽  
Mass Flow ◽  
Flow Rate ◽  
Numerical Study ◽  
Numerical Results ◽  
Centrifugal Pumps ◽  
Cavitation Threshold

Cavitation in pumps is one of the most important causes of damage to pumps impellers/inducers. A numerical model is developed here to simulate the pump hydraulics in different conditions. Experiments are also conducted to validate the computer simulations. To verify the numerical model, the h–m˙ (head versus mass flow rate) of the model is compared with the experimental data. The system is then run under cavitation state. Two methods are applied to monitor the cavitation threshold: first by using stroboscope and observing cavitation bubbles through the transparent casing of the pump and second by checking the NPSHA value for cavitation based on ISO3555. The paper then compares the experimental and numerical results to find the strengths and weaknesses of the numerical model.

scholarly journals Determination of critical operating and geometrical parameters in diesel injectors through one dimensional modelling, design of experiments and an analysis of variance

2017 ◽  
Vol 232 (13) ◽  
pp. 1762-1781 ◽  
Author(s):  
Francisco J Salvador ◽  
Marcos Carreres ◽  
Marco Crialesi-Esposito ◽  
Alejandro H Plazas
Keyword(s):  
Design Of Experiments ◽  
Mass Flow Rate ◽  
Analysis Of Variance ◽  
Mass Flow ◽  
Flow Rate ◽  
Control Volume ◽  
Geometrical Parameters ◽  
One Dimensional ◽  
Injection Process ◽  
Rate Profile

In this paper, a design of experiments and a statistical analysis of variance (ANOVA) are performed to determine the parameters that have more influence on the mass flow rate profile in diesel injectors. The study has been carried out using a one dimensional model previously implemented by the authors. The investigation is split into two different parts. First, the analysis is focused on functional parameters such as the injection and discharge pressures, the energizing time and the fuel temperature. In the second part, the influence of 37 geometrical parameters, such as the diameters of hydraulic lines, calibrated orifices and internal volumes, among others, are analysed. The objective of the study is to quantify the impact of small variations in the nominal value of these parameters on the injection rate profile for a given injector operating condition. In the case of the functional parameters, these small variations may be attributed to possible undesired fluctuations in the conditions that the injector is submitted to. As far as the geometrical and flow parameters are concerned, the small variations studied are representative of manufacturing tolerances that could influence the injected mass flow rate. As a result, it has been noticed that the configuration of the inlet and outlet orifices of the control volume, together with the discharge coefficient of the inlet orifice, among a few others, play a remarkable role in the injector performance. The reason resides in the fact that they are in charge of controlling the behaviour of the pressure in the control volume, which importantly influences injector dynamics and therefore the injection process. Variations of only 5% in the diameter of these orifices strongly modify the shape of the rate of injection curve, influencing both the injection delay and the duration of the injection process, consequently changing the total mass delivered.

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