Analytical Modeling and Performance Study of a Cross Flow Air Dehumidifier Using Liquid Desiccant

2014 ◽  
Vol 875-877 ◽  
pp. 1205-1213 ◽  
Author(s):  
Mohamed M. Bassuoni
Keyword(s):  
Numerical Solutions ◽  
Removal Rate ◽  
Cross Flow ◽  
Operating Conditions ◽  
Maximum Deviation ◽  
Performance Study ◽  
Liquid Desiccant ◽  
Mass Transfer Processes ◽  
And Performance ◽  
Air Conditioning Systems

The dehumidifier is a key component in liquid desiccant air conditioning systems. Various mathematical models of heat and mass transfer processes inside the dehumidifier are introduced and numerically solved in the literature. Analytical solutions have more advantages than numerical solutions in studying the dehumidifier performance parameters. This paper presents the results from an analytical model for the performance of an adiabatic cross flow liquid desiccant air dehumidifier. Calcium chloride is used as desiccant material in this investigation. Both humidity and temperature effectiveness of the dehumidifier are used to predict the performance of the device under various operating conditions. Good accuracy has been found between analytical solution and reliable experimental results with a maximum deviation of +6.63% and -5.65% in the moisture removal rate. The method developed here can be used in the quick prediction of the dehumidifier performance. The exit parameters from the dehumidifier are evaluated under the effects of variables such as air temperature and humidity, desiccant temperature and concentration and air to desiccant flow rates. The results show that hot humid air and desiccant concentration have the greatest impact on the performance of the dehumidifier.

Determination of cost-efficient cooling power range for improving the performance of internally cooled ultrasonic atomization liquid desiccant dehumidifiers

2020 ◽  
Vol 29 (9) ◽  
pp. 1260-1276
Author(s):  
Zili Yang ◽  
Lu-An Chen ◽  
Ruiyang Tao ◽  
Ke Zhong
Keyword(s):  
Power Efficiency ◽  
Removal Rate ◽  
Operating Conditions ◽  
Cooling Power ◽  
Internal Cooling ◽  
Liquid Desiccant ◽  
Improvement Rate ◽  
Ultrasonic Atomization ◽  
Internally Cooled ◽  
Cost Efficient

Liquid desiccant dehumidifiers (LDDs) can be improved by adding internal cooling. However, the addition of excessive cooling power may deteriorate the system‘s cost-efficiency, whereas the addition of insufficient cooling power leads to negligible performance improvements. The objective of this study is to determine the suitable cost-efficient cooling power range for improving the performance of internally cooled LDDs (IC-LDDs). A novel method and a set of criteria related to the moisture removal rate, cooling-power efficiency ( ηc) and coefficient of dehumidification performance from cooling power ( DCOPcooling) were proposed to determine cost-efficient cooling power. The internally cooled ultrasonic atomization liquid desiccant system (IC-UADS), together with a well-validated model based on the conservation laws of mass and energy and the sensible heat balance, was adopted to demonstrate the analysis. The results showed that, although the dehumidification performance improves with increasing cooling power, the improvement rate decreases, while ηcand DCOPcoolingdecline quickly (by 87.9%). For cost-efficient improvement, the necessary power proportion of internal cooling to the system‘s target dehumidification capacity tends to be stable, which was about 29% for the IC-UADS, and independent of the operating conditions. The results may help to determine the reasonable cooling power range for cost-efficient improvement of IC-LDDs.

scholarly journals Performance of Pure Crossflow Heat Exchanger in Sensible Heat Transfer Application

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5489
Author(s):  
Karthik Silaipillayarputhur ◽  
Tawfiq Al-Mughanam
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Research Work ◽  
Cross Flow ◽  
Operating Conditions ◽  
Sensible Heat ◽  
Process Industries ◽  
Flow Heat ◽  
And Performance ◽  
Marginal Improvement

All process industries involve the usage of heat exchanger equipment and understanding its performance during the design phase is very essential. The present research work specifies the performance of a pure cross flow heat exchanger in terms of dimensionless factors such as number of transfer units, capacity rate ratio, and heat exchanger effectiveness. Steady state sensible heat transfer was considered in the analysis. The matrix approach that was established in the earlier work was used in the study. The results were depicted in the form of charts, tables, and performance equations. It was observed that indeterminately increasing the number of transfer units past a threshold limit provided very marginal improvement in the performance of a pure cross flow heat exchanger. Likewise, flow pattern in a heat exchanger is usually assumed either as mixed or unmixed. However, due to various operating conditions, partially mixed conditions do exist. This work considers partially mixed conditions in the tube side of the heat exchanger. The correction factor for heat exchanger effectiveness was developed to accommodate partially mixed flow conditions in the pure cross flow heat exchanger.

scholarly journals Performance Prediction of Cross-Flow Fans Using Mean Streamline Analysis

2005 ◽  
Vol 2005 (2) ◽  
pp. 112-116 ◽  
Author(s):  
Jae-Won Kim ◽  
Eun Young Ahn ◽  
Hyoung Woo Oh
Keyword(s):  
Performance Prediction ◽  
Cross Flow ◽  
Prediction Method ◽  
General Purpose ◽  
Operating Conditions ◽  
Performance Predictions ◽  
Performance Curves ◽  
Mean Streamline Analysis ◽  
And Performance ◽  
Cross Flow Fan

This paper presents the mean streamline analysis using the empirical loss correlations for performance prediction of cross-flow fans. Comparison of overall performance predictions with test data of a cross-flow fan system with a simplified vortex wall scroll casing and with the published experimental characteristics for a cross-flow fan has been carried out to demonstrate the accuracy of the proposed method. Predicted performance curves by the present mean streamline analysis agree well with experimental data for two different cross-flow fans over the normal operating conditions. The prediction method presented herein can be used efficiently as a tool for the preliminary design and performance analysis of general-purpose cross-flow fans.

scholarly journals Feasibility of Liquid Desiccant Cooling (LDC) system under Mediterranean climate

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Seifennasr Sabek
Keyword(s):  
Air Conditioning ◽  
Mediterranean Climate ◽  
Removal Rate ◽  
Analytical Investigation ◽  
Liquid Desiccant ◽  
Humid Climate ◽  
Air Stream ◽  
Hot And Humid Climates ◽  
Mathematical Equations ◽  
Air Conditioning Systems

Contrary to the conventional air conditioning systems, the liquid desiccant cooling (LDC) systems are considered efficient systems to control the indoor air conditions. In addition, the LDC technologies are more adequate for the hot and humid climates. In this paper, we present an analytical investigation at assessing the feasibility of a LDC technology under Mediterranean climate. The mathematical equations including the sensible and latent heat transfer equations in both air stream and desiccant solution are presented. The impacts of climatic and operating parameters on the supplied air qualities, moisture removal rate (MRR) and sensible heat ratio (SHR) are evaluated. As a consequence, this study provides a solution to investigate the feasibility of this type of air conditioning technologies under hot and humid climate.

Experimental analysis and performance optimization of a counter-flow enthalpy recovery device using liquid desiccant

2018 ◽  
Vol 39 (6) ◽  
pp. 679-697 ◽  
Author(s):  
Xiaochen Liu ◽  
Xiaohua Liu ◽  
Tao Zhang ◽  
Ying Xie
Keyword(s):  
Performance Optimization ◽  
Air Conditioning ◽  
Cross Flow ◽  
Transfer Model ◽  
Liquid Desiccant ◽  
Air Velocity ◽  
Counter Flow ◽  
Packed Tower ◽  
Enthalpy Recovery ◽  
Air Conditioning Systems

The liquid desiccant enthalpy recovery is an efficient way to save energy in air-conditioning systems. In this study, a counter-flow liquid desiccant enthalpy recovery device was proposed and experimentally analyzed. Enthalpy transfer capacity, enthalpy efficiency and pressure drop per height of packing were used as indices to describe its performances. Based on the experiment results, the heat and mass transfer model of a packed tower was used to simulate and optimize the performance of this device. The maximum enthalpy efficiency and enthalpy transfer capacity were achieved when the optimal air velocity (1.9–2.1 m/s in this study) maintained to be slightly below the air velocity at the loading point and the thermal capacity ratio of air to desiccant ( m*) equaled to 1. These conclusions are valuable to both design and operation of such an enthalpy recovery device. Practical application: A counter-flow enthalpy recovery device with liquid desiccant was proposed and experimentally investigated. Based on the experiment results, a numerical model for this device was built and validated. The optimal air and desiccant mass fluxes were analyzed to maximize the enthalpy efficiency of this device, which could be higher than the conventional device with cross-flow pattern. These results could provide guidelines for both design and operation management of counter-flow enthalpy recovery devices in liquid desiccant-based air-conditioning systems.

scholarly journals Design, construction and performance study of a cascade impactor for reducing diesel particulate emission

1970 ◽  
Vol 39 (1) ◽  
pp. 26-29
Author(s):  
Md Shamim Akhter ◽  
SM Najmul Hoque ◽  
Md Nurun Nabi
Keyword(s):  
Collection Efficiency ◽  
Stokes Number ◽  
Cascade Impactor ◽  
Operating Conditions ◽  
Performance Study ◽  
Engine Emissions ◽  
Engine Exhaust ◽  
Particulate Emission ◽  
Brake Thermal Efficiency ◽  
And Performance

In this paper, the design and construction of a cascade impactor for reducing particulate emission from a diesel engine exhaust has been presented and experiments have been carried out to determine its collection efficiency. The cascade impactor designed in this work consists of four stages having successive decreasing nozzle diameter so as to capture successive smaller diameter particles in the stages. The successive nozzle diameters (D) were selected 2.1cm, 1.7cm, 1.3cm and 0.9cm. Also the distances between nozzle and impaction plate (S) were taken as 2.1cm, 1.4cm, 0.9cm and 0.45cm respectively so that S/D for succeeding stages becomes 1, 0.82, 0.7 and 0.5 respectively. In this investigation, collection efficiency of the cascade impactor based on different engine operating conditions has been determined. Effect of fitting the cascade impactor to engine exhaust on different engine parameters and engine emissions were also found out. At a constant speed of 1000 rpm, a maximum collection efficiency of about 85% of the impactor was obtained at a load of 6kg. A slight decrease in brake thermal efficiency of the engine with the cascade impactor was also noticed. However, by fitting the cascade impactor to the engine, CO and NOx emissions were found to decrease. Keywords: Real impactor, cascade impactor, Reynolds number, Stokes number, collection efficiency. doi:10.3329/jme.v39i1.1830 Journal of Mechanical Engineering, vol. ME39, No. 1, June 2008 26-29

scholarly journals Energy Performance Evaluation of a Ventilated Façade System through CFD Modeling and Comparison with International Standards

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 193
Author(s):  
Sofia Pastori ◽  
Riccardo Mereu ◽  
Enrico Sergio Mazzucchelli ◽  
Stefano Passoni ◽  
Giovanni Dotelli
Keyword(s):  
Solar Radiation ◽  
Energy Savings ◽  
Fluid Dynamic ◽  
Energy Performance ◽  
Operating Conditions ◽  
International Standards ◽  
Cfd Modeling ◽  
And Performance ◽  
Ventilated Facade ◽  
Air Conditioning Systems

Ventilated façades can help to reduce summer building thermal loads and, therefore, energy consumption due to air-conditioning systems thanks to the combined effect of the solar radiation reflection and the natural or forced ventilation into the cavity. The evaluation of ventilated façades behavior and performance is complex and requires a complete thermo-fluid dynamic analysis. In this study, a computational fluid dynamic (CFD) methodology has been developed for the complete assessment of the energy performance of a prefabricated timber–concrete composite ventilated façade module in different operating conditions. Global numerical results are presented as well as local ones in terms of heat flux, air velocity, and temperature inside the façade cavity. The results show the dependency of envelope efficiency on solar radiation, the benefits that natural convection brings on potential energy savings and the importance of designing an optimized façade geometry. The results concerning the façade behavior have been thoroughly compared with International Standards, showing the good accuracy of the model with respect to these well-known procedures. This comparison allowed also to highlight the International Standards procedures limits in evaluating the ventilated façade behavior with the necessary level of detail, with the risk of leading to design faults.

Economic Feasibility and Performance Study of a Solar-Powered Absorption Cycle Using Some Aqueous Salt Solutions

1997 ◽  
Vol 119 (1) ◽  
pp. 31-34 ◽  
Author(s):  
I. H. Malik ◽  
M. Altamush Siddiqui
Keyword(s):  
Economic Feasibility ◽  
Operating Conditions ◽  
The Other ◽  
Solar Collectors ◽  
Performance Study ◽  
Wide Range ◽  
And Performance ◽  
Solar Powered ◽  
Economic Analyses ◽  
Absorption Cycle

Economic analyses of solar collectors, for optimizing generator temperatures in the absorption cycle using aqueous solutions of LiBr, LiBr–ZnBr2, LiBr–ZnBr2LiCl, and LiBr–ZnCl2–CaBr2 salts, have been carried out for a wide range of the operating conditions. Ordinary collectors with two glass covers and evacuated-tubular collectors have been selected as the sources of energy for providing hot liquid in the generator of the absorption cycle. Of the four solutions, as the working fluids in the absorption cycles, those having better coefficients of performance are the LiBr/H2O at the low evaporator temperatures, and the (LiBr–ZnBr2–LiCl)/H2O as well as the (LiBr–ZnCl2–CaBr2)/H2O at the high evaporator temperatures. Similarly, costs of the solar collectors are low, at low evaporation temperatures for the LiBr/H2O and at high temperatures for the other two solutions; the (LiBr–ZnBr2)/H2O, on the other hand, have relatively low COP and high operating costs.

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