scholarly journals Absorption Refrigeration Systems Based on Ammonia as Refrigerant Using Different Absorbents: Review and Applications

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 48
Author(s):  
Alvaro A. S. Lima ◽  
Gustavo de N. P. Leite ◽  
Alvaro A. V. Ochoa ◽  
Carlos A. C. dos Santos ◽  
José A. P. da Costa ◽  
...  
Keyword(s):  
Solar Energy ◽  
Energy Demand ◽  
Low Cost ◽  
Lithium Bromide ◽  
Industrial Sector ◽  
Lithium Nitrate ◽  
Absorption Refrigeration ◽  
Absorption Chiller ◽  
Absorption Chillers ◽  
Private And Public

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 their main advantage over the conventional vapor compression system. Currently, the solution pairs used in commercial absorption chillers are lithium bromide/water and ammonia/water. The latter pair has been used in air conditioning and industrial processes due to the ammonia operation’s low temperature. Few review papers on absorption chillers have been published, discussing the use of solar energy as the input source of the systems, the evolution of the absorption refrigeration cycles over the last decades, and promising alternatives to increase the performance of absorption refrigeration systems. There is a lack of consistent studies about designing requirements for absorption chillers, so an updated review covering recent advances and suggested solutions to improve the use and operation of those absorption refrigeration systems using different working fluids is relevant. Hence, this presents a review of the state-of-the-art of ammonia/absorbent based absorption refrigeration systems, considering the most relevant studies, describing the development of this equipment over the years. The most relevant studies in the open literature were collected to describe this equipment’s development over the years, including thermodynamic properties, commercial manufacturers, experimental and numerical studies, and the prototypes designed and tested in this area. The manuscript focuses on reviewing studies in absorption refrigeration systems that use ammonia and absorbents, such as water, lithium nitrate, and lithium nitrate plus water. As a horizon to the future, the uses of absorption systems should be rising due to the increasing values of the electricity, and the environmental impact of the synthetic refrigerant fluids used in mechanical refrigeration equipment. In this context, the idea for a new configuration absorption chiller is to be more efficient, pollutant free to the environment, activated by a heat substantiable source, such as solar, with low cost and compactness structure to attend the thermal needs (comfort thermal) for residences, private and public buildings, and even the industrial and health building sector (thermal processes). To conclude, future recommendations are presented to deal with the improvement of the refrigeration absorption chiller by using solar energy, alternative fluids, multiple-effects, and advanced and hybrid configurations to reach the best absorption chiller to attend to the thermal needs of the residential and industrial sector around the world.

scholarly journals Performance Study of a Novel Integrated Solar Combined Cycle System

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3400 ◽  
Author(s):  
Liqiang Duan ◽  
Zhen Wang
Keyword(s):  
Solar Energy ◽  
Meteorological Data ◽  
Lithium Bromide ◽  
Combined Cycle ◽  
Air Cooling ◽  
Absorption Refrigeration ◽  
Performance Study ◽  
Levelized Cost Of Electricity ◽  
Cycle System ◽  
New System

Based on a traditional integrated solar combined cycle system, a novel integrated solar combined cycle (ISCC) system is proposed, which preferentially integrates the solar energy driven lithium bromide absorption refrigeration system that is used to cool the gas turbine inlet air in this paper. Both the Aspen Plus and EBSILON softwares are used to build the models of the overall system. Both the thermodynamic performance and economic performance of the new system are compared with those of the traditional ISCC system without the inlet air cooling process. The new system can regulate the proportions of solar energy integrated in the refrigerator and the heat recovery steam generator (HRSG) based on the daily meteorological data, and the benefits of the solar energy integrated with the absorption refrigeration are greater than with the HRSG. The results of both the typical day performance and annual performance of different systems show that the new system has higher daily and annual system thermal efficiencies (52.90% and 57.00%, respectively), higher daily and annual solar photoelectric efficiencies (31.10% and 22.31%, respectively), and higher daily and annual solar photoelectric exergy efficiencies (33.30% and 23.87%, respectively) than the traditional ISCC system. The solar energy levelized cost of electricity of the new ISCC system is 0.181 $/kW·h, which is 0.061 $/kW·h lower than that of the traditional ISCC system.

The Modeling of Air-Cooled Absorption Chiller Integration in CHP System

2004 ◽  
Author(s):  
Xiaohong Liao ◽  
Patricia Garland ◽  
Reinhard Radermacher
Keyword(s):  
Control Strategies ◽  
Lithium Bromide ◽  
Absorption Chiller ◽  
Absorption Chillers ◽  
Operation Conditions ◽  
Bromide Solution ◽  
Exhaust Heat ◽  
Lithium Bromide Solution ◽  
Prime Movers ◽  
Chp System

Absorption chillers are well suited for the use of exhaust heat from prime movers, and they improve the heat utilization of Cooling, Heating, and Power (CHP) systems. An air-cooled absorption chiller eliminates the cooling tower and brings considerable advantages as compared to water-cooled chillers. However, the expensive capital cost and crystallization of LiBr (Lithium Bromide) solution in certain operation conditions restrict the commercialization of air-cooled LiBr absorption machines. This paper discusses the feasibility of air-cooled absorption in CHP systems, where the control strategies based on the application can avoid the occurrence of crystallization. By using the fundamental thermodynamic principle, steady-state thermodynamic modeling and simulation have been done in Engineer Equation Solver (EES) to predict the operation of air-cooled absorption chiller integration in CHP systems with special consideration of the crystallization limits. The data of field operation acquired from a CHP system at UMD are used for validation.

Modeling an Integral Dual Solar/Gas Fired Generator for a Water-Lithium Bromide Absorption Chiller

1999 ◽  
Author(s):  
Jiming Cao ◽  
Richard N. Christensen
Keyword(s):  
Heat Transfer ◽  
Natural Gas ◽  
Solar Energy ◽  
Current Flow ◽  
Lithium Bromide ◽  
Absorption Chiller ◽  
Transfer Resistance ◽  
Subcooled Liquid ◽  
Bromide Solution ◽  
Lithium Bromide Solution

Abstract This paper presents a design process for a dual solar/gas fired generator. A generator fired by solar energy and/or natural gas for a water-lithium bromide absorption chiller of 25 refrigeration tons (RT) was modeled. The natural gas is considered as the backup heat when the solar energy is unavailable or insufficient. The flue gas and the water-lithium bromide solution are in co-current flow, while the solar fluid and the water-lithium bromide solution are in counter-current flow. Fifty fluted tubes were installed vertically between two concentric cylindrical tubes. A solid ceramic insert was used to enhance heat transfer on the gas side that is considered as having the dominant heat transfer resistance. The burner is installed inside the smaller cylindrical tube. The solar fluid from the solar collector enters the generator through the fluted tubes while the water-lithium bromide mixture flows in the annular channel around the fluted tubes as a subcooled liquid. The generator is divided into two regions according to the heat transfer mechanism: subcooled liquid region and desorption region. In this model, a simultaneous solar and gas fired desorption process was investigated. The amount of makeup heat needed from natural gas was determined as a function of the solar fluid flow rate. Local temperature profiles were predicted by the model.

Performance Evaluation of a 4.5 kW (1.3 Refrigeration Tons) Air-Cooled Lithium Bromide/Water Hot-Water-Fired Absorption Unit

2007 ◽  
Author(s):  
Abdolreza Zaltash ◽  
Andrei Petrov ◽  
Randall Linkous ◽  
Edward Vineyard ◽  
David Goodnack ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Air Conditioning ◽  
Cooling Tower ◽  
Lithium Bromide ◽  
Cooling Capacity ◽  
Hot Water ◽  
Next Generation ◽  
Absorption Chiller ◽  
Flow Rates ◽  
Absorption Chillers

During the summer months, air-conditioning (cooling) is the single largest use of electricity in both residential and commercial buildings with the major impact on peak electric demand. Improved air-conditioning technology has by far the greatest potential impact on the electric industry compared to any other technology that uses electricity. Thermally activated absorption air-conditioning (absorption chillers) can provide overall peak load reduction and electric grid relief for summer peak demand. This paper describes an innovative absorption technology based on integrated rotating heat exchangers to enhance heat and mass transfer resulting in a potential reduction of size, cost, and weight of the “next generation” absorption units. This absorption chiller (RAC) is a 4.5 kW (1.3 refrigeration tons or RT) air-cooled lithium bromide (LiBr)/water unit powered by hot water generated using the solar energy and/or waste heat. Typically LiBr/water absorption chillers are water-cooled units which use a cooling tower to reject heat. Cooling towers require a large amount of space and increase start-up and maintenance costs. However, RAC is an air-cooled absorption chiller which requires no cooling tower. The purpose of this evaluation is to verify RAC performance by comparing the Coefficient of Performance (COP or ratio of cooling capacity to thermal energy input) and the cooling capacity results with those of the manufacturer. The performance of the RAC was tested at Oak Ridge National Laboratory (ORNL) in a controlled environment at various hot and chilled water flow rates, air handler flow rates, and ambient temperatures. Temperature probes, mass flow meters, rotational speed measuring device, pressure transducers, and a web camera mounted inside the unit were used to monitor the RAC via a web control-based data acquisition system using Automated Logic Controller (ALC). Results showed a COP and cooling capacity of approximately 0.58 and 3.7 kW respectively at 35°C (95°F) design condition for ambient temperature with 40°C (104°F) cooling water temperature. This is in close agreement with the manufacturer data of 0.60 for COP and 3.9 kW for cooling capacity. Future work will use these performance results to evaluate the potential benefits of rotating heat exchangers in making the “next-generation” absorption chillers more compact and cost effective without any significant degradation in the performance. Future studies will also evaluate the feasibility of using rotating heat exchangers in other applications.

Heat Current Method Based Modeling and Optimization of a Solar-Driven Absorption Chiller for Residential Houses

2019 ◽  
Author(s):  
Qun Chen ◽  
Tian Zhao
Keyword(s):  
Solar Energy ◽  
Current Method ◽  
Global Constraints ◽  
Storage Device ◽  
Optimized Design ◽  
Heat Current ◽  
Refrigeration System ◽  
Absorption Chiller ◽  
Absorption Chillers ◽  
Operation Cost

Abstract The utilization of solar energy is attracting rapidly increasing researches due to its many advantages, and an important application is to satisfy the refrigeration demand of residents with the solar-assisted absorption chillers. However, the simple solar-assisted refrigeration system cannot always meet the cooling demand of residents due to the mismatch between solar power and the refrigeration load. Therefore, the thermal energy storage device is introduced into the solar-assisted system to increase the stability of the refrigeration system and reduce the waste of solar energy. In this contribution, a solar-assisted absorption chiller system together with the TES device is presented and optimized to minimize the operation cost of the system. The system is modeled using the newly proposed heat current method and its global constraints are constructed, which largely reduces the number of the constraints comparing to the traditional equation-oriented approach. Optimization results present that the optimized design of the system reduces the total operation cost effectively.

Design and Commissioning of an Experimental Set-Up to Evaluate the Performance of a Solar Absorption Chiller With Thermal Storage

2015 ◽  
Author(s):  
Christopher Baldwin ◽  
Cynthia A. Cruickshank ◽  
Daniel Bowie
Keyword(s):  
Energy Demand ◽  
Complete System ◽  
Thermal Storage ◽  
Absorption Chiller ◽  
Solar Absorption ◽  
Residential Sector ◽  
Absorption Chillers ◽  
Peak Loads ◽  
Thermally Driven ◽  
Set Up

As the demand for cooling increases in Canada, it creates a greater energy demand on the utility grid by placing peak loads during the summer months. As a result, air conditioning in the residential sector is responsible for a disproportionately large and increasing amount of CO2 emissions in Canada. One potential solution is the use of solar thermally driven absorption chillers, however before their widespread use in Canada is possible, extensive testing and optimization of the systems must be conducted to determine their feasibility in the Canadian climate. This paper discusses a full scale experimental test rig that has been recently constructed and commissioned to experimentally evaluate the performance of a commercially available solar absorption chiller with integrated thermal storage. The complete system is described, including the system’s test capabilities, the instrumentation installed, the control system developed, and the calibration and uncertainty analysis completed on each individual sensor and the system as a whole. Additionally, the paper examines the charge cycle of the solar absorption chiller being studied, and compares the results to simulation results obtained from a TRNSYS model of the test apparatus.

Thin Film Solar Cell: Characteristics and Characterizations

2015 ◽  
Vol 1116 ◽  
pp. 51-58 ◽  
Author(s):  
Mohammad Kamal Hossain
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Solar Energy ◽  
Thin Film Solar Cell ◽  
Energy Demand ◽  
Low Cost ◽  
Clean Energy ◽  
Manufacturing Cost ◽  
Human Society

In recent decades, due to some urgent and unavoidable issues, such as increasing energy demand, climate change, global warming, etc., the R&D of renewable energies have become inevitable to pave way the sustainable development of human society. In this regard, solar power is widely considered as the most appealing clean energy since there is no other one being as abundant as the sun. The amount of solar energy reaching our earth within one hour equals to the total annual energy need of all of humankind. Since the energy resources on Earth are being exhausted, solar energy have to serve as the main energy source in coming century and beyond. The photovoltaic solar cells developed so far have been based on silicon wafers, with this dominance likely to continue well into the future. The surge in manufacturing volume as well as emerging technologies over the last decade has resulted in greatly decreased costs. Therefore, several companies are now well below the USD 1 W−1 module manufacturing cost benchmark that was once regarded as the lowest possible with this technology. Thin-film silicon, such as hydrogenated amorphous silicon (a-Si), microcrystalline silicon (mc-Si) and related alloys, are promising materials for very low-cost solar cells. Here in this article, a brief description of thin film solar cell technologies followed by deferent state-of-art tools used for characterizing such solar cells are explored. Since characteristics of thin-film solar cells are the main ingredient in defining efficiency, the inherent properties are also mentioned alongside the characterizations.

Modeling an Integral Dual Solar/Gas-Fired Generator for a Water-Lithium Bromide Absorption Chiller

2000 ◽  
Vol 122 (4) ◽  
pp. 217-223 ◽  
Author(s):  
J. Cao ◽  
R. N. Christensen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Solar Energy ◽  
Lithium Bromide ◽  
Design Procedure ◽  
Absorption Chiller ◽  
Convective Boiling ◽  
Desorption Process ◽  
The Heat Transfer Coefficient ◽  
Driving Source

This paper presents a design procedure for a dual solar/gas-fired generator of an absorption chiller. The solar energy is the primary driving source for the generator, while the natural gas serves as the backup heat when the solar energy is unavailable or insufficient. Saturated forced convective boiling for binary mixtures has been considered to account for the reduction in the heat transfer coefficient observed for most mixtures. The simultaneous solar and gas-fired desorption process was investigated. The generator constructed based on modeling results yielded good performance in the experiment. [S0195-0738(00)00704-4]

Design and Testing of an Augmented Generator for Solar Fired Absorption Chillers

Solar Energy ◽  
2003 ◽  
Author(s):  
James Bergquam ◽  
Joseph Brezner ◽  
Andrew Jensen
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Lithium Bromide ◽  
Double Effect ◽  
Coefficient Of Performance ◽  
Solar Collectors ◽  
Absorption Chiller ◽  
Pressurized Water ◽  
Absorption Chillers ◽  
Design And Testing

This paper presents results from a project sponsored by the California Energy Commission that involved the design and testing of an augmented generator for a solar fired, double effect absorption chiller. Solar powered absorption chillers use water heated by an array of solar collectors to boil a solution of lithium bromide and water. The energy transfer process between pressurized water heated by the solar collectors and the LiBr/H2O solution is the focus of this study. A method of augmenting the heat transfer in the generator was developed, bench tested and implemented in an operating 70kW solar HVAC system. The augmented design involved installing twisted stainless steel inserts in the tubes where the LiBr/H2O solution boils and refrigerant vapor is generated. The inserts increased the overall heat transfer coefficient between the heat medium in the shell side of the generator and the LiBr/H2O solution in the tubes. A solar-fired, double effect absorption chiller requires the collector array and storage tank to operate at temperatures in excess of 150°C. At these temperatures, the heating water must be at a pressure of about 700kPa to prevent it from boiling. This combination of high temperature and high pressure requires that the collectors, storage tanks, pumps, valves and piping be designed according to pressure vessel codes. This increases the initial cost of the system and also requires significant maintenance. The main objective of this work is to develop a method of lowering the requirements for a 150°C heating medium. The ultimate goal is to operate at about 120°C while maintaining the Coefficient of Performance and cooling capacity of the absorption chiller. The results presented in this paper show that the generator with twisted inserts can operate with an average log mean temperature difference of 10°C. The average COP of the chiller is about 1.0 and the chiller provided all of the cooling required by a 743 m2 building. Without the twisted inserts, the generator operated with a temperature difference of 22 to 28°C. The inserts provide significant reduction in the operating temperature of the solar collectors and do not adversely affect the performance of the double effect absorption chiller.

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