The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Moh’d A. Al-nimr - One of the best experts on this subject based on the ideXlab platform.
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MHD free convection flow in open-ended vertical porous channels
Chemical Engineering Science, 1999Co-Authors: Moh’d A. Al-nimr, M. A. HaderAbstract:Abstract Analytical solutions for fully developed MHD natural convection flow in open-ended vertical porous channels are presented. Four fundamental boundary conditions have been investigated and the corresponding fundamental solutions are obtained. These four fundamental boundary conditions are obtained by combining each of the two conditions of having one boundary maintained at uniform heat flux or at uniform wall Temperature with each of the conditions that the opposite boundary is kept isothermal at the Inlet Fluid Temperature or adiabatic. Expressions for the flow and heat transfer parameters are given for each case. These fundamental solutions may be used to obtain solutions satisfying more general thermal boundary conditions.
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Dynamic behaviour of baffled solar air heaters
Renewable Energy, 1998Co-Authors: Moh’d A. Al-nimr, Rebhi A. DamsehAbstract:A mathematical model describes the dynamic thermal behaviour of a baffled solar air heater is presented. The transient behaviour of the heater results from sudden changes in the intensity of the incident solar radiation and the Inlet Fluid Temperature. In terms of the presented model, analytical solutions for the Fluid and solid domains are derived. Also, expression for the thermal efficiency of the heater is presented. The effects of different design parameters on the thermal performance of the heater are investigated. The validity of the theoretical model is verified experimentally where it is found that both theoretical and experimental results are in a good agreement.
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Dynamic behaviour of a packed bed energy storage system
Energy Conversion and Management, 1996Co-Authors: Moh’d A. Al-nimr, Moh'd Abu-qudais, M.d. MashaqiAbstract:A mathematical model describing the dynamic thermal behaviour of a packed bed energy storage column is presented. The model predicts the Temperature distribution in the column for a variable Inlet Fluid Temperature. In terms of the presented model, analytical solutions for the Fluid and rock domains are derived. The analytical solutions are verified experimentally, where it is found that both theoretical and experimental results are in a good agreement.
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A THEORETICAL AND EXPERIMENTAL STUDY
International Journal of Solar Energy, 1996Co-Authors: Moh'd Abu-qudais, Moh’d A. Al-nimrAbstract:A Iheoreticat and experimental model which describes the transient behaviour of a matrix solar air heater is presented. The transient behaviour of the heater results from sudden changes in the intensity of the incident solar radiation and the Inlet Fluid Temperature. The Temperature distributions in both the Fluid and the solid matrix domains are given exactly, and experiments are conducted to verify the validity of the theoretical model. There was good agreement between the measured and predicted values.
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MHD free-convection flow in open-ended vertical concentric porous annuli
Applied Energy, 1995Co-Authors: Moh’d A. Al-nimrAbstract:Abstract Analytical solutions for fully developed MHD natural-convection flow in open-ended vertical concentric porous annuli are presented. Four fundamental boundary conditions have been investigated and the corresponding fundamental solutions are obtained. These four fundamental boundary conditions are obtained by combining each of the two conditions of having one boundary maintained at uniform heat flux or at uniform wall Temperature with each of the conditions that the opposite boundary is kept isothermal at the Inlet Fluid Temperature or adiabatic. Expressions for the flow and heat-transfer parameters are given for each case. These fundamental solutions may be used to obtain solutions satisfying more general thermal boundary conditions.
Donggen Peng - One of the best experts on this subject based on the ideXlab platform.
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an improved evaluation method for thermal performance of borehole heat exchanger
Renewable Energy, 2015Co-Authors: Changxing Zhang, Ping Chen, Donggen PengAbstract:Thermal performance of vertical U-pipe borehole heat exchanger (BHE) is an important research subject for the design and application of ground-coupled heat pump system (GCHPs). This paper presents an improved evaluation method for thermal performance of BHE based on analytical solution model, which is validated by comparing with duct storage system (DST) model and field experiment. Using the evaluation method, impacts of Inlet Fluid Temperature, Fluid flow rate and borehole depth on thermal performance of two types of U-pipe BHEs are studied. The study provides a good alternative of the experimental method for thermal performance test (TPT) and a useful thermal performance evaluation tool for BHEs in GCHPs.
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an improved evaluation method for thermal performance of borehole heat exchanger
Renewable Energy, 2015Co-Authors: Changxing Zhang, Ping Chen, Donggen PengAbstract:Thermal performance of vertical U-pipe borehole heat exchanger (BHE) is an important research subject for the design and application of ground-coupled heat pump system (GCHPs). This paper presents an improved evaluation method for thermal performance of BHE based on analytical solution model, which is validated by comparing with duct storage system (DST) model and field experiment. Using the evaluation method, impacts of Inlet Fluid Temperature, Fluid flow rate and borehole depth on thermal performance of two types of U-pipe BHEs are studied. The study provides a good alternative of the experimental method for thermal performance test (TPT) and a useful thermal performance evaluation tool for BHEs in GCHPs.
Chin Pan - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation in the pressure drop characteristics of supercritical carbon dioxide in the uniformly heated horizontal miniature tubes
The Journal of Supercritical Fluids, 2020Co-Authors: Lei Wang, Yu Cheng Pan, Jin Der Lee, Yan Wang, Chin PanAbstract:Abstract This study investigates experimentally the pressure drop characteristics of supercritical carbon dioxide uniformly heated in horizontal circular smooth tubes. The results illustrate that channel pressure drop would be enlarged with increases in mass flux and Inlet Fluid Temperature, while it would decrease with increases in outlet pressure and tube diameter. Frictional pressure drop is the most dominant contributor (51%–85%) for total pressure drop, while accelerational pressure drop, up to 28%, and form loss, up to 24%, would contribute substantially with the increase of tube diameter due to significant reduction of Fluid density at the channel outlet. Several classic correlations for turbulent flow and non-isothermal correlations for supercritical Fluids are examined in smooth tubes. In overall, the existing empirical correlations could reasonably predict the frictional pressure drop within a relative error of about 30% against the present data set under uniform heating conditions.
Juan C. Ordonez - One of the best experts on this subject based on the ideXlab platform.
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Dynamic 3D volume element model of a parabolic trough solar collector for simulation and optimization
Applied Energy, 2018Co-Authors: Sam Yang, Tugba S. Sensoy, Juan C. OrdonezAbstract:Abstract This paper presents a dynamic three-dimensional volume element model of a parabolic trough solar collector coupled to an existing semi-finite optical model for simulation and optimization. The spatial domain in the volume element model is discretized with lumped control volumes (i.e., volume elements) in cylindrical coordinates according to the predefined collector geometry. The spatial dependency of the model is therefore taken into account without the need to solve partial differential equations. The proposed model combines the laws of thermodynamics and heat transfer as well as empirical correlations to simplify the modeling and expedite the computations, and the resulting system of ordinary differential equations is integrated in time for Temperature. The model was validated with the experimental data provided in the literature, and was employed to evaluate the sensitivity of the collector performance described by the first and second law efficiencies to receiver length, annulus gap spacing, concentration ratio, incidence angle, Inlet Fluid Temperature and flow rate. This work also examined the effects of Inlet Fluid Temperature and Temperature differential on dynamic collector performance in the transient case study. Results showed that the first law efficiency was most sensitive to the Inlet Fluid Temperature with the maximum variation of 30%, whereas the incidence angle and concentration ratio affected the second law efficiency the most with the maximum variations of 375% and 300%, respectively. The remaining parameters featured trivial effects in all cases. In the transient analysis, higher Temperature differential and lower Inlet Fluid Temperature yielded higher total heat gain while the total exergy gain was insensitive to both parameters. The first law efficiency should therefore be of greater importance than the second law efficiency in the control of dynamic collector performance based on these two parameters.
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Heat transfer Fluids for parabolic trough solar collectors - a comparative study
2016 IEEE Conference on Technologies for Sustainability (SusTech), 2016Co-Authors: Reuben Buehler, Sam Yang, Juan C. OrdonezAbstract:In this work we compared three heat transfer Fluids (HTFs) for parabolic trough solar collectors (PTCs), namely, Syltherm 800, Therminol VP-1, and Dowtherm Q. For the assessment, we adopted and simplified a previously developed mathematical model of a parabolic trough solar receiver comprising an outer cover, annular space, abosrber, and heat transfer Fluid, and discretized the governing equations using the finite difference method. Subsequently, we validated the model with the experimental data available in the literature and employed it to study the following: (1) the effects of annular pressure on the collector performance for the three HTFs and (2) collector performance subject to different concentration ratios (i.e., aperture area) and Inlet HTF Temperatures. Simulation results demonstrate the meager thermal performance of Syltherm 800 compared to Therminol VP-1 and Dowtherm Q that achieve similar performance. In addition, we show that there is an optimal aperture area and Inlet Fluid Temperature for Syltherm 800 that yield maximum collector efficiency. Henceforth, we anticipate this work to provide a rough guideline on the selection of an appropriate HTF for future PTCs from the thermal standpoint.
Ahmad Kamandi - One of the best experts on this subject based on the ideXlab platform.
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exergy efficiency investigation and optimization of an al2o3 water nanoFluid based flat plate solar collector
Energy and Buildings, 2015Co-Authors: Ehsan Shojaeizadeh, Farzad Veysi, Ahmad KamandiAbstract:Abstract The present study aims to investigate exergy efficiency of a Flat-plate solar collector containing Al2O3–water nanoFluid as base Fluid. The effect of various parameters like mass flow rate of Fluid, nanoparticle volume concentration, collector Inlet Fluid Temperature, solar radiation, and ambient Temperature on the collector exergy efficiency is investigated. Also, the procedure to determine optimum values of nanoparticle volume concentration, mass flow rate of Fluid, and collector Inlet Fluid Temperature for maximum exergy efficiency delivery has been developed by means of interior-point method for constrained optimization under the given conditions. According to the results, each of these parameters can differently affect the collector exergy by changing the value of the other parameters. The optimization results indicate that under the actual constraints, in both pure water and nanoFluid cases the optimized exergy efficiency is increased with increasing solar radiation value. By suspending Al2O3 nanoparticles in the base Fluid (water) the maximum collector exergy efficiency is increased about 1% and also the corresponding optimum values of mass flow rate of Fluid and collector Inlet Fluid Temperature are decreased about 68% and 2%, respectively.
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Exergy efficiency investigation and optimization of an Al2O3–water nanoFluid based Flat-plate solar collector
Energy and Buildings, 2015Co-Authors: Ehsan Shojaeizadeh, Farzad Veysi, Ahmad KamandiAbstract:Abstract The present study aims to investigate exergy efficiency of a Flat-plate solar collector containing Al2O3–water nanoFluid as base Fluid. The effect of various parameters like mass flow rate of Fluid, nanoparticle volume concentration, collector Inlet Fluid Temperature, solar radiation, and ambient Temperature on the collector exergy efficiency is investigated. Also, the procedure to determine optimum values of nanoparticle volume concentration, mass flow rate of Fluid, and collector Inlet Fluid Temperature for maximum exergy efficiency delivery has been developed by means of interior-point method for constrained optimization under the given conditions. According to the results, each of these parameters can differently affect the collector exergy by changing the value of the other parameters. The optimization results indicate that under the actual constraints, in both pure water and nanoFluid cases the optimized exergy efficiency is increased with increasing solar radiation value. By suspending Al2O3 nanoparticles in the base Fluid (water) the maximum collector exergy efficiency is increased about 1% and also the corresponding optimum values of mass flow rate of Fluid and collector Inlet Fluid Temperature are decreased about 68% and 2%, respectively.
