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R Best - One of the best experts on this subject based on the ideXlab platform.
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characteristics of an ammonia Lithium Nitrate double effect heat pump transformer
Applied Thermal Engineering, 2016Co-Authors: Christopher Heard, W Rivera, R BestAbstract:Abstract The modelled operating characteristics of an ammonia/Lithium Nitrate double effect absorption heat pump-transformer (Type III absorption heat pump) are presented and compared to other working pair options and absorption heat pump cycles. Heat and mass balance equations are given. The effect of sub-optimal cycle design is shown on cycle thermal efficiency and solution pump power. It is shown that the ammonia/Lithium Nitrate working pair would achieve a performance a little less efficient than a water/Lithium bromide system but is somewhat more tolerant of less than optimum operating conditions with respect to cycle thermal efficiency and solution pump power. Ratios of useful heat delivered to driving heat of nearly four are shown to be achievable with this system.
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experimental results of a direct air cooled ammonia Lithium Nitrate absorption refrigeration system
Applied Thermal Engineering, 2014Co-Authors: S U Llamasguillen, R Cuevas, R Best, V H GomezAbstract:Abstract Absorption thermal cooling systems driven by renewable energy are a viable option in order to reduce fossil fuel consumption and the associated emissions. This work shows the results of an air cooled absorption cooling prototype working with an ammonia–Lithium Nitrate mixture at high ambient temperatures. An absorption refrigeration system was designed and built. The prototype is a one stage ammonia–Lithium Nitrate air cooled chiller. The experimental system was instrumented to evaluate each component. This paper shows the operation conditions in the experimental unit as well as some of the heat loads encountered at different operating conditions. The system was operated successfully at ambient temperatures in the range of 25–35 °C. A series of test showed that even at ambient temperatures it can be operated at evaporator temperatures below 10 °C producing chilled water for air conditioning applications such as radiative cooling panels. The system proved to stabilize very quickly and no risk of crystallization was encountered so the first results are promising in order to continue with the development of a more advanced prototype.
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comparison of the experimental evaluation of a solar intermittent refrigeration system for ice production operating with the mixtures nh3 lino3 and nh3 lino3 h2o
Renewable Energy, 2012Co-Authors: G Morenoquintanar, W Rivera, R BestAbstract:A solar powered intermittent absorption refrigeration system has been developed and evaluated with the ammonia/Lithium Nitrate (NH3/LiNO3) and ammonia/Lithium Nitrate/water (NH3/LiNO3/H2O) mixtures. The system, designed to produce up to 8 kg/day of ice, was developed in the Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico. It consists of a Compound Parabolic Concentrator (CPC) with a cylindrical receiver acting as the generator/absorber during the generation and evaporation stages respectively, a condenser, an evaporator and an expansion device. The system operates solely with solar energy and no moving parts are required. Several test runs were carried out at different solution concentrations for both mixtures under study. Evaporator temperatures as low as −8 °C were obtained for a time period of 8 h. Comparing the performance of the system operating with the two mixtures, it was found that with the ternary mixture the solar coefficients of performance can be up to 24% higher than those obtained with the binary mixture, varying from 0.066 to 0.093. In addition, with the ternary mixture the initial generation temperatures resulted to be up to 5.5 °C lower than those obtained with the ammonia/Lithium Nitrate mixture, at the same time the maximum operating pressures were around 1.5 bar higher.
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evaluation of a solar intermittent refrigeration system for ice production operating with ammonia Lithium Nitrate
Solar Energy, 2011Co-Authors: W Rivera, R Best, G Morenoquintanar, C O Rivera, F MartinezAbstract:Abstract A novel solar intermittent refrigeration system for ice production developed in the Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico is presented. The system operates with the ammonia/Lithium Nitrate mixture. The system developed has a nominal capacity of 8 kg of ice/day. It consists of a cylindrical parabolic collector acting as generator–absorber. Evaporator temperatures as low as −11 °C were obtained for several hours with solar coefficients of performance up to 0.08. It was found that the coefficient of performance increases with the increment of solar radiation and the solution concentration. A dependency of the coefficient of performance was not founded against the cooling water temperature. Also it was found that the maximum operating pressure increases meanwhile the generation temperature decreases with an increase of the solution concentration.
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boiling heat transfer coefficients inside a vertical smooth tube for water ammonia and ammonia Lithium Nitrate mixtures
International Journal of Heat and Mass Transfer, 1999Co-Authors: W Rivera, R BestAbstract:Abstract This paper describes the experimental results obtained on the heat transfer in forced convective boiling for the water/ammonia and ammonia/Lithium Nitrate mixtures flowing upward in a vertical tube uniformly heated. The concentration range for both mixtures was 38–48 wt%. Correlations were proposed to correlate the experimental local heat transfer coefficients with a mean deviation of ±16% for the ammonia/Lithium Nitrate mixture and ±25% for the ammonia/water mixture. The results showed that the local heat transfer coefficients are strongly dependent on Bo for the ammonia/Lithium Nitrate mixture and more dependent on quality and 1/ X tt for the ammonia/water mixture at the analysed conditions. Comparing the heat transfer coefficient values for both mixtures, it was observed that the lowest values were obtained with the ammonia/Lithium Nitrate mixture.
Alberto Coronas - One of the best experts on this subject based on the ideXlab platform.
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part load characteristics of a new ammonia Lithium Nitrate absorption chiller
International Journal of Refrigeration-revue Internationale Du Froid, 2015Co-Authors: M. Zamora, Mahmoud Bourouis, Alberto Coronas, Marta VallèsAbstract:Abstract A pre-industrial prototype of a new water-cooled ammonia/Lithium Nitrate absorption chiller was characterised at part-load operation mode. The chiller was built using brazed plate heat exchangers in all its components, including the absorber and the generator. A test campaign was carried out varying the thermal load in the chilled water circuit and keeping the hot and cooling water temperatures constant. Part-load curves of the thermal and electrical coefficients of performance were obtained, plotted and compared with data from the literature on small capacity absorption chillers with conventional working pairs, namely ammonia/water and water/Lithium bromide. The experimental results showed that to achieve a higher electrical coefficient of performance at part-load operation, it was much more convenient to use an ON-OFF control than to modify the hot water temperature. Furthermore, using a simple ON-OFF control strategy, the behaviour of the new absorption chiller was more agile and responded more quickly. The part-load curve of the electrical coefficient of performance was obtained by adjusting the experimental data to the shape of the curve proposed in the standard prEN-14825:2011 for air-to-water chillers. The Cc coefficient was 0.7985 matching the value obtained dividing the remaining electrical consumption measured during the OFF half cycles by the total energy consumption generated.
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pre industrial development and experimental characterization of new air cooled and water cooled ammonia Lithium Nitrate absorption chillers
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Miguel Zamora, Mahmoud Bourouis, Alberto Coronas, Manel VallesAbstract:Abstract Two pre-industrial prototypes of a new ammonia/Lithium Nitrate absorption chiller, a water-cooled one and an air-cooled one, have been built and experimentally characterized. The single-effect configuration of the absorption refrigeration cycle was selected for both prototypes in which brazed plate heat exchangers were used in all thermal components. These prototypes, designed for air conditioning applications, were tested under various operating conditions to assess their performance. The water-cooled prototype yields 12.9 kW of cooling capacity and an electrical COPelec of 19.3, when operating at a 15 °C chilled water temperature, 90 °C hot water temperature and a 35 °C cooling water temperature. In the case of the air-cooled prototype, at a 15 °C chilled water temperature, 90 °C hot water temperature and a 35 °C ambient air temperature, the cooling capacity is 9.3 kW and the electrical COPelec is 6.5.
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densities viscosities and heat capacities of ammonia Lithium Nitrate and ammonia Lithium Nitrate water solutions between 293 15 and 353 15 k
Journal of Chemical & Engineering Data, 2008Co-Authors: Simona Libotean, Daniel Salavera, Xavier Esteve, Manel Valles, Andreu Martin, Alberto CoronasAbstract:The density, dynamic viscosity, and heat capacity of ammonia + Lithium Nitrate and ammonia + Lithium Nitrate + water mixtures were measured between (293.15 and 353.15) K at 1.8 MPa, using a vibrating-tube densimeter, a piston-style viscosimeter, and a heat flux Calvet-type calorimeter, respectively. The measured data were correlated as a function of temperature and composition using simple polynomial equations. Kinematic viscosity data of binary and ternary mixtures were also determined.
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vapor liquid equilibrium of ammonia Lithium Nitrate water and ammonia Lithium Nitrate solutions from 293 15 to 353 15 k
Journal of Chemical & Engineering Data, 2007Co-Authors: Simona Libotean, Daniel Salavera, Manel Valles, And Xavier Esteve, Alberto CoronasAbstract:The vapor pressure of ammonia + Lithium Nitrate + water and ammonia + Lithium Nitrate mixtures was measured by a static method from (293.15 to 353.15) K in ammonia mass fractions ranging from 0.2 to 0.6. The experimental vapor pressure data were correlated with the temperature and the liquid-phase composition using an analytical polynomial equation. The capability of the electrolyte nonrandom two liquid (E-NRTL) model to predict the vapor−liquid equilibrium (VLE) of the ternary mixture was evaluated by comparing predicted and experimental data of the ammonia + Lithium Nitrate + water solutions. The binary interaction parameters of ammonia + Lithium Nitrate needed for the prediction of ternary VLE were determined from binary experimental data.
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solubility heat capacity and density of Lithium bromide Lithium iodide Lithium Nitrate Lithium chloride aqueous solutions at several compositions and temperatures
Journal of Chemical & Engineering Data, 2004Co-Authors: Daniel Salavera, Xavier Esteve, Kashinath R Patil, Ana M Mainar, Alberto CoronasAbstract:The Lithium bromide + Lithium iodide + Lithium Nitrate + Lithium chloride (mole ratio 5:1:1:2) aqueous solution is a potential working fluid for air-cooled absorption chillers. Three important thermophysical properties were measured: solubility, heat capacity, and density. The solubilities were measured, in the temperature range (276.04 to 353.21) K, using visual polythermal and calorimetric methods. Heat capacities were measured in the range of temperatures from (312.63 to 372.08) K and a range of total salt mass fraction of (0.4953 to 0.6394). Liquid densities were measured at 1.0 MPa from (303.15 to 423.15) K and total salt mass fraction from (0.5150 to 0.6594). In addition, the Young's rule was checked for density predictions in the reported system at (305.15 and 323.15) K and 0.1 MPa. For this purpose, densities of the quaternary salt and Lithium iodide aqueous solutions were measured at 0.1 MPa and several temperatures and concentrations. All the experimental data were correlated using empirical po...
W Rivera - One of the best experts on this subject based on the ideXlab platform.
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characteristics of an ammonia Lithium Nitrate double effect heat pump transformer
Applied Thermal Engineering, 2016Co-Authors: Christopher Heard, W Rivera, R BestAbstract:Abstract The modelled operating characteristics of an ammonia/Lithium Nitrate double effect absorption heat pump-transformer (Type III absorption heat pump) are presented and compared to other working pair options and absorption heat pump cycles. Heat and mass balance equations are given. The effect of sub-optimal cycle design is shown on cycle thermal efficiency and solution pump power. It is shown that the ammonia/Lithium Nitrate working pair would achieve a performance a little less efficient than a water/Lithium bromide system but is somewhat more tolerant of less than optimum operating conditions with respect to cycle thermal efficiency and solution pump power. Ratios of useful heat delivered to driving heat of nearly four are shown to be achievable with this system.
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experimental assessment of an absorption cooling system operating with the ammonia Lithium Nitrate mixture
Energy, 2014Co-Authors: J A Hernandezmagallanes, L A Dominguezinzunza, G Gutierrezurueta, P Soto, C Jimenez, W RiveraAbstract:This paper reports the experimental results of a single effect absorption cooling system of 3 kW of nominal cooling capacity operating with ammonia–Lithium Nitrate solution. The system was designed and built in the Instituto de Energias Renovables of the Universidad Nacional Autonoma de Mexico and can be used for food conservation or air conditioning. The absorber and generator are falling film heat exchangers. The condenser, evaporator and solution heat exchanger are compact plate heat exchangers. The heat was supplied to the generator at temperatures between 85 °C and 105 °C, while the cooling water temperatures to remove the heat produced during the condensation and absorption varied between 18 °C and 36 °C. The results showed that the system can produce up to 2.7 kW of cooling capacity at heating water temperatures of 95 °C and can achieve evaporator temperatures as low as 1 °C. The experimental coefficients of performance varied between 0.45 and 0.70. Because of the developed system do not need a rectifier and reasonable good coefficients of performance were achieved, the developed system seems to be a good alternative to be used for food conservation or air conditioning.
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comparison of the experimental evaluation of a solar intermittent refrigeration system for ice production operating with the mixtures nh3 lino3 and nh3 lino3 h2o
Renewable Energy, 2012Co-Authors: G Morenoquintanar, W Rivera, R BestAbstract:A solar powered intermittent absorption refrigeration system has been developed and evaluated with the ammonia/Lithium Nitrate (NH3/LiNO3) and ammonia/Lithium Nitrate/water (NH3/LiNO3/H2O) mixtures. The system, designed to produce up to 8 kg/day of ice, was developed in the Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico. It consists of a Compound Parabolic Concentrator (CPC) with a cylindrical receiver acting as the generator/absorber during the generation and evaporation stages respectively, a condenser, an evaporator and an expansion device. The system operates solely with solar energy and no moving parts are required. Several test runs were carried out at different solution concentrations for both mixtures under study. Evaporator temperatures as low as −8 °C were obtained for a time period of 8 h. Comparing the performance of the system operating with the two mixtures, it was found that with the ternary mixture the solar coefficients of performance can be up to 24% higher than those obtained with the binary mixture, varying from 0.066 to 0.093. In addition, with the ternary mixture the initial generation temperatures resulted to be up to 5.5 °C lower than those obtained with the ammonia/Lithium Nitrate mixture, at the same time the maximum operating pressures were around 1.5 bar higher.
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evaluation of a solar intermittent refrigeration system for ice production operating with ammonia Lithium Nitrate
Solar Energy, 2011Co-Authors: W Rivera, R Best, G Morenoquintanar, C O Rivera, F MartinezAbstract:Abstract A novel solar intermittent refrigeration system for ice production developed in the Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico is presented. The system operates with the ammonia/Lithium Nitrate mixture. The system developed has a nominal capacity of 8 kg of ice/day. It consists of a cylindrical parabolic collector acting as generator–absorber. Evaporator temperatures as low as −11 °C were obtained for several hours with solar coefficients of performance up to 0.08. It was found that the coefficient of performance increases with the increment of solar radiation and the solution concentration. A dependency of the coefficient of performance was not founded against the cooling water temperature. Also it was found that the maximum operating pressure increases meanwhile the generation temperature decreases with an increase of the solution concentration.
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modeling of an intermittent solar absorption refrigeration system operating with ammonia Lithium Nitrate mixture
Solar Energy Materials and Solar Cells, 2003Co-Authors: C Rivera, W RiveraAbstract:Abstract The theoretical performance of an intermittent absorption refrigeration system operating with ammonia–Lithium Nitrate mixture is presented. The analysis was done for representative days of each season of 2001. Meteorological data were taken from a local meteorological station installed in the Energy Research Centre of the National University of Mexico in Temixco, Morelos, Mexico. The system consists of a generator-absorber, a condenser, a valve and an evaporator. A compound parabolic concentrator (CPC) with a glass cover, operates as the generator-absorber of the cooling system. Since Lithium Nitrate does not evaporate during the generation, it is not necessary to use a rectifier. The theoretical efficiencies of the CPC varied from 0.78 to 0.33 depending on the time of the day and the season. Also, the results showed that with the proposed system it is possible to produce up to 11.8 kg of ice at generation temperatures around 120°C and condensation temperatures between 40°C and 44°C. These temperatures allow the system to be chilled with air or water. The overall efficiencies of the systems were between 0.15 and 0.4 depending on the generation and condenser temperatures. The efficiencies are satisfactory considering the simplicity of the system.
Hristo Iglev - One of the best experts on this subject based on the ideXlab platform.
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icelike vibrational properties of strong hydrogen bonds in hydrated Lithium Nitrate
Journal of Physical Chemistry A, 2020Co-Authors: Daniel Hutzler, Klara Stallhofer, Reinhard Kienberger, Eberhard Riedle, Hristo IglevAbstract:The hydrogen bond network accounts for many of the extraordinary physical properties of liquid water and ice. Its vibrational dynamics are quite complex in their entirety but can be accessed in det...
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dynamics of weak bifurcated and strong hydrogen bonds in Lithium Nitrate trihydrate
Journal of Physical Chemistry Letters, 2011Co-Authors: Jasper C Werhahn, Stanislav Pandelov, Sotiris S Xantheas, Hristo IglevAbstract:The properties of three distinct types of hydrogen bonds, namely a weak, a bifurcated, and a strong one, all present in the LiNO3·(HDO)(D2O)2 hydrate lattice unit cell are studied using steady-state and time-resolved spectroscopy. The lifetimes of the OH stretching vibrations for the three individual bonds are 2.2 ps (weak), 1.7 ps (bifurcated), and 1.2 ps (strong). For the first time, the properties of bifurcated H bonds can thus be unambiguously directly compared to those of weak and strong H bonds in the same system. The values of their OH stretching vibration lifetime, anharmonicity, red shift, and bond strength lie between those for the strong and weak H bonds. The experimentally observed inhomogeneous broadening of their spectral signature can be partly attributed to the coupling with a low frequency intermolecular wagging vibration.
R Ventas - One of the best experts on this subject based on the ideXlab platform.
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performance analysis of an absorption double effect cycle for power and cold generation using ammonia Lithium Nitrate
Applied Thermal Engineering, 2017Co-Authors: R Ventas, Agustina Lecuona, C Vereda, M C RodriguezhidalgoAbstract:Abstract The performance of a two-stage double-effect absorption machine for combined power and cold generation is proposed and studied theoretically, generating innovative schemes. The ammonia/Lithium Nitrate solution allows this cycle, consuming either solar thermal or residual heat. The machine is represented by means of a thermodynamic steady-state cycle. First, only power generation and only cold production are separately studied as function of the main internal temperatures, introducing the concepts of mixed and unmixed vapour and of virtual temperatures for allowing comparison. The results indicate that for producing power the efficiency of the cycle increases when rising the maximum pressure while for producing cold is the contrary. The maximum efficiency obtained for only power production with no superheating is 19.5% at a high generation temperature of 173 °C and at a moderate 20.3 bars of maximum pressure. The solution crystallization avoids a higher efficiency. The combined power and cooling cycle allows adapting the energy production to cold demand or to power demand by splitting the vapour generated. At a generation temperature of 132 °C, when splitting the vapour generated into half for power and half for cooling, the cycle obtains an electric efficiency of 6.5% and a COP of 0.52. This cycle is compared to a conventional double-effect cycle configured in parallel flow, obtaining the same electric efficiency but with a 32% higher COP .
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two stage double effect ammonia Lithium Nitrate absorption cycle
Applied Thermal Engineering, 2016Co-Authors: R Ventas, Agustina Lecuona, C Vereda, Mathieu LegrandAbstract:Abstract The two-stage configuration of a double-effect absorption cycle using ammonia/Lithium Nitrate as working fluid is studied by means of a thermodynamic model. The maximum pressure of this cycle configuration is the same as the single-effect cycle, up to 15.8 bars, being an advantage over the double-effect conventional configuration with three pressure levels that exhibits much higher maximum pressure. The performance of the cycle and the limitation imposed by crystallization of the working fluid is determined for both adiabatic and diabatic absorber cycles. Both cycles offer similar COP ; however the adiabatic variant shows a larger margin against crystallization. This cycle can produce cold for external inlet evaporator temperatures down to −10 °C, but for this limit the crystallization could happen at high inlet generator temperatures. The maximum COP can be 1.25 for an external inlet generator temperature of 100 °C. This cycle shows a better COP than a typical double effect cycle with in-parallel configuration for the range of the moderate temperatures under study and using the same working fluid. Comparisons with double effect cycles using H 2 O/LiBr and NH 3 /H 2 O as working fluids are also offered, highlighting the present configurations advantages regarding COP , evaporation and condensation temperatures as well as crystallization.
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experimental evaluation of ammonia adiabatic absorption into ammonia Lithium Nitrate solution using a fog jet nozzle
Applied Thermal Engineering, 2013Co-Authors: Alejandro Zacarias, Agustina Lecuona, M Venegas, R VentasAbstract:Abstract This paper presents the experimental assessment of the adiabatic absorption of ammonia vapour into an ammonia–Lithium Nitrate solution using a fog jet nozzle. The ammonia mass fraction was kept constant at 46.08% and the absorber pressure was varied in the range 355–411 kPa. The nozzle was located at the top of the absorption chamber, at a height of 205 mm measured from the bottom surface. The diluted solution flow rate was modified between 0.04 and 0.08 kg s −1 and the solution inlet temperature in the range 25.9–30.2 °C. The influence of these variables on the approach to adiabatic equilibrium factor, outlet subcooling, absorption ratio and mass transfer coefficient is analysed. The approach to adiabatic equilibrium factor for the conditions essayed is always between 0.82 and 0.93. Pressure drop of the solution entering the absorption chamber is also evaluated. Correlations for the approach to adiabatic equilibrium factor and the Sherwood number are given.
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subcooled and saturated boiling of ammonia Lithium Nitrate solution in a plate type generator for absorption machines
International Journal of Heat and Mass Transfer, 2012Co-Authors: M Venegas, Alejandro Zacarias, Agustina Lecuona, C Vereda, R VentasAbstract:Abstract This paper presents the experimental heat transfer evaluation during subcooled and saturated boiling of ammonia–Lithium Nitrate solution in a fusion plate heat exchanger, acting as a vapor generator under operating conditions representative of single-effect absorption machines. The solution flow rate and outlet temperature were modified in the ranges of 0.041–0.083 kg/s and 78–97 °C, respectively. The region where vapor bubbles begin to arise is estimated using a correlation for the wall superheat required for the onset of nucleate boiling. Results show that subcooled boiling is present in the generator. The initial boiling temperature is about 3.1 °C lower than the saturation temperature. The influence of the heat and mass fluxes on the boiling heat transfer coefficient is analyzed. The paper offers a correlation for the Nusselt number, including the subcooled and saturated boiling regions.
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Experimental assessment of ammonia adiabatic absorption into ammonia-Lithium Nitrate solution using a flat fan nozzle.
Applied Thermal Engineering, 2011Co-Authors: A. Zacarías, R Ventas, M Venegas, Agustina LecuonaAbstract:This paper presents the experimental evaluation of the adiabatic absorption of ammonia vapour into ammonia-Lithium Nitrate solution using a flat fan nozzle and an upstream single-pass subcooler. Data are representative of the working conditions of adiabatic absorbers in absorption chillers. The nozzle was located at the top of the absorption chamber, separated 205 mm from the bottom surface. The diluted solution mass flow rate was modified between 0.04 - 0.08 kg/s and the solution inlet temperature between 24.5 - 29.7 °C. The influence of these variables on the absorption ratio, mass transfer coefficient, outlet subcooling and approach to equilibrium factor is analysed in the present paper. A linear relation between the inlet subcooling and the absorption ratio is observed. The approach to equilibrium factor for the conditions essayed is always between 0.81 and 0.89. Mass transfer coefficients and correlations for the approach to equilibrium factor and the Sherwood number are obtained. Results are compared with other ones reported in the literature.