Advantages and disadvantages of ammonia/absorbent working fluids for absorption systems.

Advantages and disadvantages of ammonia/absorbent working fluids for absorption systems.

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The interest in employing absorption refrigeration systems is usually related to electricity’s precariousness since these systems generally use thermal rejects for their activation. The application of these systems is closely linked to the concept of energy polygeneration, in which the energy demand to operate them is reduced, which represents thei...

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... 3 summarizes works found on the thermodynamic properties of the ternary mixture NH 3 /(LiNO 3 + H 2 O). Table 4 shows the advantages and disadvantages of ammonia/absorbent working fluids for absorption systems. ...

Citations

... Zacarias et al. [12] explored the thermodynamic properties of binary mixtures containing ammonia, and they reached the efficiency of the cycles [13]. Lima et al. [14] proposed the functional properties of the new working fluid as a substitute for H 2 O/Li-Br in an absorption refrigeration cycle. Researchers conducted a simulation to investigate the optimal cooling air absorption operating conditions and design [15]. ...
Article
This research paper aims to perform dynamics analysis, 3E assessment including energy, exergy, exergoeconomic, and the multi-objective evolutionary optimization on a novel solar Li-Br absorption refrigeration cycle. The research is time-dependent, owing to solar radiation variability during different timelines. Theoretically, all the necessary thermodynamic, energy, and exergy equations are applied initially. This is followed by the thermoeconomic analysis, which takes place after defining the designing variables during the thermoeconomic optimization process and is presented together with the economic relations of the system and its thermoeconomic characteristics. Furthermore, the sensitivity analysis is undertaken, the source of system inefficiency is determined, the multi-objective evolutionary optimization of the whole system is carried out, and the optimal values are compared with the primary stage. Engineering Equation Solver (EES) software has been used to accomplish comprehensive analyses. As part of the validation process, the results of the research are compared with those published previously and are found to be relatively consistent.
... In this study, a numerical model was developed for single-stage ammonia/water absorption chillers. The system was composed of Plate Heat Exchangers (PHEs), making the overall structure compact [3,7]. The off-design cycle model integrated detailed heat exchanger models. ...
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Ammonia/water absorption chillers are driven by low-grade heat and cover wide refrigeration temperatures. This paper analyses single-stage ammonia/water absorption chillers. A numerical model was developed based on the heat exchanger performance. The model captures variational heat exchanger performances and describes the actual cycle with varying boundary conditions. The detrimental effects of refrigerant impurity were analysed quantitatively under different operating conditions. The model was validated with experimental data. A basic cycle and three advanced cycles were analysed for sub-zero refrigeration by comparing the thermodynamic performances. A compression-assisted cycle extended the activation temperature from 80 to 60 °C. At the heat source of 120 °C, when a counter-current desorber or bypassed rich solution was used, the COP increased from 0.51 to 0.58 or 0.57, respectively. The operating parameters included the heat source temperatures, heat sink temperatures, the mass flow rates and mass concentrations of rich solutions. Higher heat source temperatures increase cooling capacity. The increase was around 20 kW for the basic cycle of sub-zero refrigeration. There is an optimum heat source temperature maximising the COP. Higher heat source temperatures increased the refrigerant mass flow rate and reduced the mass concentration. The mass concentration can decrease from 0.999 to 0.960.
... The refrigeration system is divided into two major parts, namely the absorption and compression/mechanical systems (Alrwashdeh et al., 2019). Nowadays absorption systems are rarely used, because of the weaknesses that exist in the system, therefore a compression system was developed, one of which was tested in this study (Alrwashdeh & Ammari, 2019;Lima et al., 2021;Pan et al., 2020;Redhwan et al., 2016). In the compression system, the cold process begins with the compressor working to compress the refrigerant vapor, condensed in the condenser, accommodated in the holding tank, lowered the pressure in the expansion valve, evaporated in the evaporator, and sucked back in by the compressor for the next cycle. ...
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Since each refrigerant has different vaporization and condensation temperature and pressure, the capacity and working conditions of each system depend on the type of refrigerant used. The criteria for a suitable refrigerant for a refrigeration system are determined by its thermodynamic, chemical, and other factors. This research aims to analyze the capacity and scope of work of refrigerator components that use R-22 refrigerant to be replaced with HCR-22 in a 1.7 TR refrigeration fish refrigerator without having to replace components. This research was carried out from December to March, on a regular fishing vessel, Alalunga Vessel. The research was conducted by reviewing and analyzing the application of refrigerant HCR-22 and R-22 in the refrigerator unit. The results of the analysis of the capacity and scope of work of the components show that HCR-22 refrigerant has a higher advantage than R-22. These high advantages have a positive reaction to the refrigeration effect and refrigerant workload, which include an increase in heat absorption capability, a decrease in compressor and electric motor energy, a decrease in the compression ratio, an increase in the compressor coefficient achievement.
... e thermodynamic characteristics of coolants, such as liquid density, vapor density, enthalpy of evaporation, and vapor pressure, are critical to developing commercially viable low-temperature chilling circuits [7][8][9]. Research on coolants throughout the publications is extensive, but there is still a lack of empirical evidence available, and also, the data collections are often incongruent [10][11][12]. ...
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A robust machine learning algorithm known as the least-squares support vector machine (LSSVM) model was used to predict the liquid densities of 48 different refrigerant systems. Hence, a massive dataset was gathered using the reports published previously. The proposed model was evaluated via various analyses. Based on the statistical analysis results, the actual values predicted by this model have high accuracy, and the calculated values of RMSE, MRE, STD, and R2 were 0.0116, 0.158, 0.1070, and 0.999, respectively. Moreover, sensitivity analysis was done on the efficient input parameters, and it was found that CF2H2 has the most positive effect on the output parameter (with a relevancy factor of +50.19). Furthermore, for checking the real data accuracy, the technique of leverage was considered, the results of which revealed that most of the considered data are reliable. The power and accuracy of this simple model in predicting liquid densities of different refrigerant systems are high; therefore, it is an appropriate alternative for laboratory data.
... In this study, a numerical model was developed for single-stage ammonia/water absorption chillers. The system was composed of Plate Heat Exchangers (PHEs), making the overall structure compact [3,7]. The off-design cycle model integrated detailed heat exchanger models. ...
... The results revealed that as the input temperature rises, the system's performance increased. Lima et al. [12] carried out an updated evaluation of recent advancements and recommendations for improving the operation of absorption refrigeration systems using various working fluids. Because of the low temperature of the ammonia operation, ammonia-water pair is used in air conditioning and industrial processes. ...
... The evaporator collects the heat from the refrigerator and directs the saturated ammonia vapour to it. The ammonia vapour (11) is absorbed into the water by the absorber after passing through the heat exchanger a second time (12). To restart the process, the generator delivers the ammonia-water vapour mixture to the rectifier (13), and the rectifier sends the water liquid back to the generator (14). ...
... The percentage of weak solutions in states 1-3 will stay unchanged, as will the percentage of strong solutions in states 4-6. "Temperatures at Thermodynamic States 11,12,13,14,15,16,17, and 18 represent the external water circuit used to give heat to the system's components", as shown in Figure 1. The inlet and outlet temperatures of the major components of the absorption system is illustrated in Table 2. ...
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Experiments on an enhanced “Generator-Absorber-Heat Exchanger” (GAX) Vapour Absorption System (VAS) for cooling purposes were carried out using water-ammonia in present study. The new experimental setup was fabricated using modern and complex technologies for the GAX absorption system which includes tiny heat exchangers, allowing the system to be both compact and efficient. The coefficient of performance (COP) of a system was analyzed for different temperatures of Generator, Condenser, Evaporator and Absorber. The results show that the maximum performance (COP=0.63) is achieved at 25℃ Generator temperature. The system has a low carbon footprint because it does not use effluent water or tower electricity and invention enables the recovery of hot air, which may then be used for several drying applications, including agricultural drying, resulting in a fully cascaded system with a three-fold increase in Coefficient of Performance (COP). A modified VAS-GAX absorption system in present analysis be a good fit for high-performance modern cooling applications.
... In this context, the use of absorption refrigeration systems has increased over the years, thanks to its economic and environmental advantages arising mainly from the possibility that these systems have to use renewable energy for their activation [2][3][4][5]. Moreover, the application of this equipment is closely linked to the application of more efficient systems, such as polygeneration energy systems [6][7][8][9], where the energy demand to operate them is reduced, and also for applications with low-temperature heat sources [10,11]. ...
... The analysis of these systems, whether operating in the steady-state or transient regime is not so simple, since this type of simulation requires various information, such as internal temperatures, global heat coefficients, mass flows, and other parameters that are usually not easy to find and/or estimate. A widely used method to facilitate the simulation of these types of systems is the characteristic equation method, which allows the thermal loads of the components to be calculated using simple linear functions [10,[12][13][14][15][16]. Ochoa et al. [14] compared the results of theoretical modeling of an absorption cooling chiller with the results obtained from the characteristic equation, finding errors of less than 4% for most of the operating conditions examined. ...
... The use of this mixture as a working fluid in absorption refrigeration systems is based on common problems found in commercial type absorption chillers that use LiBr/H 2 O and NH 3 /H 2 O mixtures for operation [10,18,23,44,45]. The LiBr/H 2 O mixture has corrosion problems, vacuum operation, toxicity problems, and solution crystallization, limiting operation under certain conditions [10]. ...
Article
This work presents a quasi-dynamic approach to an absorption refrigeration system that uses NH3/LiNO3 as the working fluid. The goal is linked to the development and validation of a mathematical model, based on the characteristic equation method, to simulate the quasi-dynamic behavior of absorption chillers. The mathematical model was developed using the first law of thermodynamics through the conservation of mass and energy and the integration of the characteristic equation method, considering external parameters such as temperatures and flow rates of hot, cold, and chilled water circuits as the global heat transfer coefficients. The computational model was built using the F-Chart EES® software, the initial part, to facilitate the resolution of the equations (characteristic equation method). Finally, MATLAB software was used to perform the simulation with the characteristic equation and the transient model. The comparison between the experimental results found in the literature and those obtained by the developed model showed good agreement with relative errors lower than 5% within the values found in the measurement uncertainties. A sensitivity analysis was performed to verify the dynamic behavior of the absorption chiller, considering the activation, cooling, and thermal load temperatures and the products of the global heat transfer coefficients, checking the temperature, pressure, profiles, heat fluxes, and the COP of the chiller. The results showed a coherent behavior when the system was disturbed by varying activation, cooling, and chilled water temperature.
... In this context, the use of absorption refrigeration systems has increased over the years, thanks to its economic and environmental advantages arising mainly from the possibility that these systems have to use renewable energy for their activation [2][3][4][5]. Moreover, the application of this equipment is closely linked to the application of more efficient systems, such as polygeneration energy systems [6][7][8][9], where the energy demand to operate them is reduced, and also for applications with low-temperature heat sources [10,11]. ...
... The analysis of these systems, whether operating in the steady-state or transient regime is not so simple, since this type of simulation requires various information, such as internal temperatures, global heat coefficients, mass flows, and other parameters that are usually not easy to find and/or estimate. A widely used method to facilitate the simulation of these types of systems is the characteristic equation method, which allows the thermal loads of the components to be calculated using simple linear functions [10,[12][13][14][15][16]. Ochoa et al. [14] compared the results of theoretical modeling of an absorption cooling chiller with the results obtained from the characteristic equation, finding errors of less than 4% for most of the operating conditions examined. ...
... The use of this mixture as a working fluid in absorption refrigeration systems is based on common problems found in commercial type absorption chillers that use LiBr/H 2 O and NH 3 /H 2 O mixtures for operation [10,18,23,44,45]. The LiBr/H 2 O mixture has corrosion problems, vacuum operation, toxicity problems, and solution crystallization, limiting operation under certain conditions [10]. ...
Article
This work presents a quasi-dynamic approach to an absorption refrigeration system that uses NH3/LiNO3 as the working fluid. The goal is linked to the development and validation of a mathematical model, based on the characteristic equation method, to simulate the quasi-dynamic behavior of absorption chillers. The mathematical model was developed using the first law of thermodynamics through the conservation of mass and energy and the integration of the characteristic equation method, considering external parameters such as temperatures and flow rates of hot, cold, and chilled water circuits as the global heat transfer coefficients. The computational model was built using the F-Chart EES® software, the initial part, to facilitate the resolution of the equations (characteristic equation method). Finally, MATLAB software was used to perform the simulation with the characteristic equation and the transient model. The comparison between the experimental results found in the literature and those obtained by the developed model showed good agreement with relative errors lower than 5% within the values found in the measurement uncertainties. A sensitivity analysis was performed to verify the dynamic behavior of the absorption chiller, considering the activation, cooling, and thermal load temperatures and the products of the global heat transfer coefficients, checking the temperature, pressure, profiles, heat fluxes, and the COP of the chiller. The results showed a coherent behavior when the system was disturbed by varying activation, cooling, and chilled water temperature.
... In this context, the use of absorption refrigeration systems has increased over the years, thanks to its economic and environmental advantages arising mainly from the possibility that these systems have to use renewable energy for their activation [2][3][4][5]. Moreover, the application of this equipment is closely linked to the application of more efficient systems, such as polygeneration energy systems [6][7][8][9], where the energy demand to operate them is reduced, and also for applications with low-temperature heat sources [10,11]. ...
... The analysis of these systems, whether operating in the steady-state or transient regime is not so simple, since this type of simulation requires various information, such as internal temperatures, global heat coefficients, mass flows, and other parameters that are usually not easy to find and/or estimate. A widely used method to facilitate the simulation of these types of systems is the characteristic equation method, which allows the thermal loads of the components to be calculated using simple linear functions [10,[12][13][14][15][16]. Ochoa et al. [14] compared the results of theoretical modeling of an absorption cooling chiller with the results obtained from the characteristic equation, finding errors of less than 4% for most of the operating conditions examined. ...
... The use of this mixture as a working fluid in absorption refrigeration systems is based on common problems found in commercial type absorption chillers that use LiBr/H 2 O and NH 3 /H 2 O mixtures for operation [10,18,23,44,45]. The LiBr/H 2 O mixture has corrosion problems, vacuum operation, toxicity problems, and solution crystallization, limiting operation under certain conditions [10]. ...
Article
Full-text available
This work presents a quasi-dynamic approach to an absorption refrigeration system that uses NH3/LiNO3 as the working fluid. The goal is linked to the development and validation of a mathematical model, based on the characteristic equation method, to simulate the quasi-dynamic behavior of absorption chillers. The mathematical model was developed using the first law of thermodynamics through the conservation of mass and energy and the integration of the characteristic equation method, considering external parameters such as temperatures and flow rates of hot, cold, and chilled water circuits as the global heat transfer coefficients. The computational model was built using the F-Chart EES® software, the initial part, to facilitate the resolution of the equations (characteristic equation method). Finally, MATLAB software was used to perform the simulation with the characteristic equation and the transient model. The comparison between the experimental results found in the literature and those obtained by the developed model showed good agreement with relative errors lower than 5% within the values found in the measurement uncertainties. A sensitivity analysis was performed to verify the dynamic behavior of the absorption chiller, considering the activation, cooling, and thermal load temperatures and the products of the global heat transfer coefficients, checking the temperature, pressure, profiles, heat fluxes, and the COP of the chiller. The results showed a coherent behavior when the system was disturbed by varying activation, cooling, and chilled water temperature.
... For this reason, they are also experimentally studied [6,7]. An absorption refrigerator uses two fluids, which change phases, and concentration flowing through the absorber, generator, evaporator, and condenser [8,9]. The change of phase or concentration occurs due to heat and mass transfer in thin liquid layers, which flow down a solid surface (cf. Figure 3 in [4]). ...
Article
Full-text available
Refrigeration and air conditioning consume 15% of the total generated electricity. Vapor condensation devices need a heat sink which may come in the form of absorption cycles devices. Two fluids, which change phase and concentration, flow through these devices. These changes take place amid a two-phase flow in contact with a solid phase. Hence, an extended study of the velocity profiles across the thin liquid layer is necessary, which is assumed to be conducted by a laser Doppler anemometer. The preliminary studies concerning the calibration of this anemometer are reported.