The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Alberto Coronas - One of the best experts on this subject based on the ideXlab platform.
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Absorption of Organic Fluid mixtures in plate heat exchangers
International Journal of Thermal Sciences, 2003Co-Authors: Manel Vallès, Mahmoud Bourouis, Dieter Boer, Alberto CoronasAbstract:It is well known that the absorber is the key component in energy conversion systems that are based on absorption cycles. This paper describes an experimental investigation into the absorption process of Organic Fluid mixtures in an absorption system which has a spray and a plate heat exchanger. The absorber consists of an adiabatic mixing chamber with a spray, where the solution that is weak in refrigerant is sprayed into the refrigerant vapour. A two-phase mixture is formed and enters a plate heat exchanger, where the solution is cooled to complete the absorption process. We carried out experiments with different types of spray nozzles using the Organic Fluid mixtures methanol–tetraethyleneglycol dimethylether (TEGDME) and trifluoroethanol (TFE)–TEGDME. We analyse how the solution mass flow rate, absorber pressure and cooling water temperature affected the absorber performance and we discuss the results in terms of the absorber load, absorbed mass flux, degree of subcooling of the solution at the absorber outlet, solution film heat and mass transfer coefficients. The results indicate that the absorption system proposed is suitable for relatively low pressures. For water temperatures of 30 °C and absorber pressures between 2 and 6 kPa, the absorption rates for TFE–TEGDME were 1 to 2.5 g·s−1·m−2. The corresponding values for methanol–TEGDME with absorber pressures between 10 and 15 kPa were 0.4 to 1.2 g·s−1·m−2.
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Double-lift absorption refrigeration cycles driven by low-temperature heat sources using Organic Fluid mixtures as working pairs
Applied Energy, 2001Co-Authors: Marc Medrano, Mahmoud Bourouis, Alberto CoronasAbstract:At present, much interest is being shown in absorption refrigeration cycles driven by low temperature heat sources, such as solar energy or low-grade waste-heat. Double-lift absorption cycles working with ammonia-water have been recommended for refrigeration applications which require cold at 0°C and which are activated by waste heat between 70 and 100°C. This paper discusses the potential of the Organic Fluid mixtures trifluoroethanol (TFE)-tetraethylenglycol dimethylether (TEGDME or E181) and methanol-TEGDME as working pairs in series flow and vapour exchange double-lift absorption cycles. The ammonia-water mixture was used for comparison purposes. The results show that the performances of these cycles improve significantly when they have the above mentioned Organic Fluid mixtures as working pairs. For example, the coefficient of performance of the vapour exchange cycle working with TFE-TEGDME is 15% higher than with ammonia-water. In this study, we used a modular software package, which we developed for the thermodynamic properties and cycles simulation of absorption systems.
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Double-lift absorption refrigeration cycles driven by low–temperature heat sources using Organic Fluid mixtures as working pairs
Applied Energy, 2001Co-Authors: Marc Medrano, Mahmoud Bourouis, Alberto CoronasAbstract:At present, much interest is being shown in absorption refrigeration cycles driven by low temperature heat sources, such as solar energy or low-grade waste-heat. Double-lift absorption cycles working with ammonia-water have been recommended for refrigeration applications which require cold at 0°C and which are activated by waste heat between 70 and 100°C. This paper discusses the potential of the Organic Fluid mixtures trifluoroethanol (TFE)-tetraethylenglycol dimethylether (TEGDME or E181) and methanol-TEGDME as working pairs in series flow and vapour exchange double-lift absorption cycles. The ammonia-water mixture was used for comparison purposes. The results show that the performances of these cycles improve significantly when they have the above mentioned Organic Fluid mixtures as working pairs. For example, the coefficient of performance of the vapour exchange cycle working with TFE-TEGDME is 15% higher than with ammonia-water. In this study, we used a modular software package, which we developed for the thermodynamic properties and cycles simulation of absorption systems.
Akin Burak Etemoglu - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic investigation of low-temperature industrial waste-heat recovery in combined heat and power generation systems
International Communications in Heat and Mass Transfer, 2013Co-Authors: Akin Burak EtemogluAbstract:Abstract Performance analysis of an industrial waste heat-based combined heat and power systems (WHCHP) completely uses energy and exergy efficiency parameters. The effect of waste water mass flow rate, pressure and temperature, Organic Fluid types on both energy and exergy efficiencies and economical profit of the system is investigated by a computer simulation. The first step of the analysis is the selection of the suitable working Fluid. After that, in order to get the performance indicators, different scenarios are run by computer simulation for WHCHP. The most suitable working Fluid is found out as isopentane. The work output and economical profit increase while exergy destruction decreases with increasing turbine inlet pressure. On the other hand, with the increase in the energy of the process heater, the work output decreases but exergy destruction and utilization factor increase. Finally, these results clearly show that performance evaluation of WHCHP based on energy analysis is not adequate and hence more meaningful evaluation should include exergy analysis.
Chenn Q. Zhou - One of the best experts on this subject based on the ideXlab platform.
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Experimental studies on the enhanced flow boiling heat transfer and pressure drop of Organic Fluid with high saturation temperature in vertical porous coated tube
2013Co-Authors: Dong Yang, Tingkuan Chen, Zhi Shen, Chenn Q. ZhouAbstract:The characteristics of flow boiling heat transfer and pressure drop of Organic Fluid with high saturation temperature in a vertical porous coated tube are experimentally studied in this paper. The experiments are performed at evaporation pressure of 0.16-0.31MPa, mass flux of 390-790kg/m2s, and vapor quality of 0.06-0.58. The variations of heat transfer coefficient and pressure drop with vapor quality are measured and compared to the results of smooth tube. Boiling curves are generated at mass flux of 482 and 675kg/m2s. The experimental results indicate that the heat transfer coefficients of the porous tube are 1.8-3.5 times those of smooth tube, and that the frictional pressure drops of the porous tube are 1.1-2.9 times those of smooth tube. The correlations for heat transfer coefficient and frictional pressure drop are derived, in which the effect of Fluid molecular weight is included. The experiments show that significant heat transfer enhancement is accompanied by a little pressure drop penalty, the a...
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Experimental studies on the enhanced flow boiling heat transfer and pressure drop of Organic Fluid with high saturation temperature in vertical porous coated tube
2013Co-Authors: Dong Yang, Tingkuan Chen, Zhi Shen, Chenn Q. ZhouAbstract:The characteristics of flow boiling heat transfer and pressure drop of Organic Fluid with high saturation temperature in a vertical porous coated tube are experimentally studied in this paper. The experiments are performed at evaporation pressure of 0.16-0.31MPa, mass flux of 390-790kg/m2s, and vapor quality of 0.06-0.58. The variations of heat transfer coefficient and pressure drop with vapor quality are measured and compared to the results of smooth tube. Boiling curves are generated at mass flux of 482 and 675kg/m2s. The experimental results indicate that the heat transfer coefficients of the porous tube are 1.8-3.5 times those of smooth tube, and that the frictional pressure drops of the porous tube are 1.1-2.9 times those of smooth tube. The correlations for heat transfer coefficient and frictional pressure drop are derived, in which the effect of Fluid molecular weight is included. The experiments show that significant heat transfer enhancement is accompanied by a little pressure drop penalty, the application of the porous coated tube is promising in the process industries.
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Numerical simulation of flow boiling for Organic Fluid with high saturation temperature in vertical porous coated tube
International Journal of Heat and Fluid Flow, 2011Co-Authors: Dong Yang, Tingkuan Chen, Yanhua Wu, Chenn Q. ZhouAbstract:A semi-analytical model is developed for the prediction of flow boiling heat transfer inside vertical porous coated tubes. The model assumes that the forced convection and nucleate boiling coexist together in the annular flow regime. Conservations of mass, momentum, and energy are used to solve for the liquid film thickness and temperature. The heat flux due to nucleate boiling consists of those inside and outside micro-tunnels. To close the equations, a detailed analysis of various forces acting on the bubble is presented to predict its mean departure diameter. The active nucleation site density of porous layer is determined from the pool boiling correlation by introducing suppression factor. The flow boiling heat transfer coefficients of Organic Fluid (cumene) with high saturation temperature in a vertical flame-spraying porous coated tube are studied numerically. It is shown that the present model can predict most of the experimental values within ±20%. The numerical results also indicate that the nucleate boiling contribution to the overall heat transfer coefficient decreases from 50% to 15% with vapor quality increasing from 0.1 to 0.5.
Chao Liu - One of the best experts on this subject based on the ideXlab platform.
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Determining the optimal pinch point temperature difference of evaporator for waste heat recovery
Journal of the Energy Institute, 2014Co-Authors: Shu-meng Zhou, Lan Xiao, Chao LiuAbstract:Abstract From the perspective of exergy recovery, the pinch point temperature difference (PPTD) of evaporator for waste heat recovery has been optimized by exergo-economic principle using the annual net profit per transferred heat load as objective function. And for comparison, another criterion, the annual total cost per transferred heat load from the view of exergy destruction, is introduced. Taking Organic Fluid R600a as an example, the effects of thermodynamic and economic parameters on the optimal PPTD are examined. It is found that the optimal PPTD is closely related to the total investment costs of evaporator. Different trends on the optimal PPTD are provided with the variations of thermodynamic and economic parameters. And the flow exergy loss has little impact on the optimal PPTD of evaporator. The optimal PPTD from the perspective of exergy recovery is larger than that from the view of exergy destruction.
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Effect of the critical temperature of Organic Fluids on supercritical pressure Organic Rankine Cycles
Energy, 2013Co-Authors: Chao LiuAbstract:Abstract The thermal performance of supercritical pressure ORCs (Organic Rankine Cycles) is related to the critical temperature of the Organic Fluids. The heat source in this investigation was flue gas with an inlet temperature of 150 °C and an outlet temperature of 70 °C. The working Fluids were R218, R134a and R236fa. An integrated-average temperature difference was used to quantify the thermal match between the flue gas and the Organic Fluid in the evaporator. Three types of operating modes were identified: (1) a flexible operating mode for low T c (critical temperature) Fluids having operating states in a rectangular region in a plot of the turbine inlet pressures versus temperatures; (2) a bifurcated operating mode for moderate T c Fluids with one or two pressures corresponding to the turbine inlet temperature; (3) a restricted operating mode for high T c Fluids with only one turbine inlet pressure possible for the turbine inlet temperature. The high T c Organic Fluid has a small integrated-average temperature difference that yields large evaporator and system exergy efficiencies. Thus, the useful power is increased. The low T c Organic Fluid has a bad thermal match in the evaporator that leads to lower ORC (Organic Rankine Cycle) thermal performance.
Marc Medrano - One of the best experts on this subject based on the ideXlab platform.
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Double-lift absorption refrigeration cycles driven by low-temperature heat sources using Organic Fluid mixtures as working pairs
Applied Energy, 2001Co-Authors: Marc Medrano, Mahmoud Bourouis, Alberto CoronasAbstract:At present, much interest is being shown in absorption refrigeration cycles driven by low temperature heat sources, such as solar energy or low-grade waste-heat. Double-lift absorption cycles working with ammonia-water have been recommended for refrigeration applications which require cold at 0°C and which are activated by waste heat between 70 and 100°C. This paper discusses the potential of the Organic Fluid mixtures trifluoroethanol (TFE)-tetraethylenglycol dimethylether (TEGDME or E181) and methanol-TEGDME as working pairs in series flow and vapour exchange double-lift absorption cycles. The ammonia-water mixture was used for comparison purposes. The results show that the performances of these cycles improve significantly when they have the above mentioned Organic Fluid mixtures as working pairs. For example, the coefficient of performance of the vapour exchange cycle working with TFE-TEGDME is 15% higher than with ammonia-water. In this study, we used a modular software package, which we developed for the thermodynamic properties and cycles simulation of absorption systems.
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Double-lift absorption refrigeration cycles driven by low–temperature heat sources using Organic Fluid mixtures as working pairs
Applied Energy, 2001Co-Authors: Marc Medrano, Mahmoud Bourouis, Alberto CoronasAbstract:At present, much interest is being shown in absorption refrigeration cycles driven by low temperature heat sources, such as solar energy or low-grade waste-heat. Double-lift absorption cycles working with ammonia-water have been recommended for refrigeration applications which require cold at 0°C and which are activated by waste heat between 70 and 100°C. This paper discusses the potential of the Organic Fluid mixtures trifluoroethanol (TFE)-tetraethylenglycol dimethylether (TEGDME or E181) and methanol-TEGDME as working pairs in series flow and vapour exchange double-lift absorption cycles. The ammonia-water mixture was used for comparison purposes. The results show that the performances of these cycles improve significantly when they have the above mentioned Organic Fluid mixtures as working pairs. For example, the coefficient of performance of the vapour exchange cycle working with TFE-TEGDME is 15% higher than with ammonia-water. In this study, we used a modular software package, which we developed for the thermodynamic properties and cycles simulation of absorption systems.