Water-lithium Bromide Absorption Research Articles

Design and thermo-economic comparisons of large scale solar absorption air conditioning cycles

Sustainable cooling absorption technologies, using renewable energy sources, and climate-friendly cooling liquids gain more and more attention. In this work, design and thermo-economic analyses are presented to compare between two different collector types (parabolic trough and evacuated tube) by Water-Lithium Bromide absorption systems. Generally, the main component of the entire system is the absorption refrigeration chiller, the plant will then consist of three subsystems. The first subsystem is the solar system for thermal power conversion. The second subsystem is represented by the condenser and chiller absorber that need to be cooled, using a cooling tower. The third subsystem is represented by the cold circuit and the terminals of the useful cooling power produced. A case study for a sports arena with 700–800 kW total cooling load is also presented. Results reveal that parabolic trough collector combined with H2O–LiBr (PTC/H2O–LiBr) gives lower design aspects and minimum rates of hourly costs (5.2$/h), while ETC/H2O–LiBr configuration (5.6$/h). H2O–LiBr thermo-economic product cost is (0.14$/GJ). The cycle coefficient of performance COP was in the range of 0.5–0.9.

Parametric Study of a Single Effect Lithium Bromide-Water Absorption Chiller Powered by a Renewable Heat Source

Parametric Study of a Single Effect Lithium Bromide-Water Absorption Chiller Powered by a Renewable Heat Source

Design and Thermo-Economic Comparisons of an Absorption Air Conditioning System Based on Parabolic Trough and Evacuated Tube Solar Collectors

Solar absorption cycles for air conditioning systems have recently attracted much attention. They have some important advantages that aid in reducing greenhouse gas emissions. In this work, design and thermo-economic analyses are presented in order to compare between two different collector types (parabolic trough and evacuated tube) by water–lithium bromide absorption systems, and to select the best operating conditions. Generally, the system consists of three major parts. The first part is the solar field for thermal power conversion. The second part is the intermediate cycle, which contains a flashing tank and pumping system. The third part is the water lithium bromide absorption chiller. A case study for a sports arena with 700–800 kW total cooling load is also presented. Results reveal that a parabolic trough collector combined with H2O–LiBr (PTC/H2O–LiBr) gives lower design aspects and minimum rates of hourly costs (USD 5.2/h), while ETC/H2O–LiBr configuration give USD 5.6/h. The H2O–LiBr thermo-economic product cost is USD 0.14/GJ. The cycle coefficient of performance COP was in the range of 0.5 to 0.9.

Design and Thermo-Economic Comparisons of an Absorption Air Conditioning System Based on Parabolic Trough and Evacuated Tube Solar Collectors

Solar absorption cycles for air conditioning systems have recently attracted much attention. They have some important advantages that aid in reducing greenhouse gas emissions. In this work, design and thermo-economic analyses are presented in order to compare between two different collector types (parabolic trough and evacuated tube) by water–lithium bromide absorption systems, and to select the best operating conditions. Generally, the system consists of three major parts. The first part is the solar field for thermal power conversion. The second part is the intermediate cycle, which contains a flashing tank and pumping system. The third part is the water lithium bromide absorption chiller. A case study for a sports arena with 700–800 kW total cooling load is also presented. Results reveal that a parabolic trough collector combined with H2O–LiBr (PTC/H2O–LiBr) gives lower design aspects and minimum rates of hourly costs (USD 5.2/h), while ETC/H2O–LiBr configuration give USD 5.6/h. The H2O–LiBr thermo-economic product cost is USD 0.14/GJ. The cycle coefficient of performance COP was in the range of 0.5 to 0.9.

Potential Study of Solar Thermal Cooling in Sub-Mediterranean Climate

Air conditioning is becoming increasingly important in the energy supply of buildings worldwide. There has been a dramatic increase in energy requirements for cooling buildings in the Middle East and North Africa (MENA) region. This is before taking the effects of climate change into account, which will also entail a sharp increase in cooling requirements. This paper presents the potential of using a solar thermal absorption cooling system in Sub-Mediterranean Climate. Four sites in Jordan are now equipped with water-lithium bromide (H2O-LiBr) absorption chillers with a total nominal capacity of 530 kW. The focus of the paper was on the pilot system at the German Jordanian University (GJU) campus with a cooling capacity of 160 kW. The system was designed and integrated in order to support two existing conventional compression chillers with a nominal cooling capacity of 700 kW. The system was economically evaluated based on the observed cooling capacity results with a Coefficient of Performance (COP) equals 0.32, and compared with the values observed for a COP of 0.79 which is claimed by the manufacturer. Several techniques were implemented to evaluate the overall economic viability in-depth such as present worth value, internal rate of return, payback period, and levelized cost of electricity. The aforementioned economic studies showed that the absorption cooling system is deemed not feasible for the observed COP of 0.32 over a lifespan of 25 years. The net present value was equal to −137,684 JD and a payback period of 44 years which exceeds the expected lifespan of the project. Even for an optimal operation of COP = 0.79, the discounted payback period was equal to 23 years and the Levelized Cost of Electricity (LCOE) was equal to 0.65 JD/kWh. The survey shows that there are several weaknesses for applying solar thermal cooling in developing countries such as the high cost of these systems and, more significantly, the lack of experience for such systems.

Charging and discharging characteristics of absorption energy storage integrated with a solar driven double-effect absorption chiller for air conditioning applications

The operation of solar driven air conditioning systems is limited to the availability of solar radiation. Consequently, to achieve extended cooling period, energy storage is necessary. This study presents performance evaluation and charging and discharging characteristics of an absorption energy storage coupled with solar driven double-effect water-lithium bromide (H2O-LiBr) absorption system through thermodynamic modeling and simulation. The absorption energy storage stores the solar heat in the form of chemical energy during the day and discharges later for cooling application. The integrated system achieved effective cooling for about fourteen hours on daily basis. The results indicate an average coefficient of performance (COP) of 1.35 for the integrated absorption chiller-storage unit and exergy efficiency of 25%. Furthermore, the overall COP of the integrated solar cooling system is 0.99 and the overall exergy efficiency is 6.8%, while the energy storage density for typical climatic conditions of Dhahran, Saudi Arabia is found to be 444.3 MJ/m3. The energy storage density obtained from the integrated solar driven H2O-LiBr double-effect absorption system is found to be higher by 13–54% compared to other integrated systems based on single-effect configuration.

Forecasting the performance of a district solar thermal smart network in desert climate – A case study

The present paper investigates the performance of a district solar thermal smart network capable of providing the cooling, heating, and domestic hot water needs for a group of 100 villas in the desert climate of Riyadh, Saudi Arabia. Evacuated tube solar collectors are distributed over the villas’ roofs, while the hot water Lithium Bromide absorption chillers and hot phase change material thermal storage tanks are located in a centralized plant. Electrical heating elements embedded in the thermal storage tanks are considered as back up auxiliary sources in case of shortages. Using the “Design Builder” energy simulation program, a typical villa constructed as per the local thermal standard has been modeled to calculate the hourly thermal loads. These hourly profiles are the initial inputs for a Transient System Simulation (TRNSYS) model integrated with the Generic Optimization Program (GenOpt). The interaction between these two programs is used to find the optimized sizing of the solar collectors’ area and the hot thermal storage volume which could achieve the maximum thermo-economic performance with a 100% solar fraction. The hourly transient simulations over a one-year period show that this system can achieve up to 82.67% reduction in the annual electrical consumption as well as carbon dioxide emissions if compared to conventional district thermal plants. Furthermore, the smart network benefits have been revealed from three different aspects: generation source, transmission loop network, and end-user consumer. The feasibility analysis performed shows that adopting the smart network can enhance the profitability of the project by 34.89% if compared to central solar plants. Also, it gives the end-user the opportunity to participate in energy production through buying the solar collectors installed on their roofs, and thus further enhancing the reduction in their annual thermal bills from 23.13% to 82.88% in a payback period of 4 years and 11 months.

Hybrid systems based on gas turbine combined cycle for trigeneration of power, cooling, and freshwater: A comparative techno-economic assessment

The objective of this study is to develop and thoroughly evaluate several feasible hybrid trigeneration configurations based on a gas turbine combined cycle (GTCC) for generating electricity, freshwater, and cooling. Six hybrid configurations are developed by integrating different desalination and chiller systems to the GTCC. Desalination systems include multi effect distillation (MED) and reverse osmosis (RO) with pressure exchanger (PEX) and chiller systems include double effect and half effect water-lithium bromide absorption chillers (DEABC and HEABC) and a vapor compression chiller (VCC) with different working fluids. The specific goal is to identify the optimal hybridization scheme and parameters among different configurations. The economic results show that implementation of RO is more economical than a hybrid MED-RO system in which the power cycle’s condenser is replaced by a MED. Also, the use of DEABC is more economical than a HEABC and a VCC. The results demonstrate that configuration 1 in which GTCC with the wet cooling tower is integrated with DEABC and RO is the most economical configuration. For this system, the levelized costs of electricity, water, and cooling (LCOE, LCOW, LCOC) are $0.0648/kWh, $0.7219/m3 and $0.0402/ton-hr, respectively, of which LCOE and LCOC are not the lowest values among different configurations.

Сопоставление эффективности термодинамических циклов абсорбционных бромисто-литиевых холодильных машин

The energy efficiency analysis of the actual thermodynamic cycles of lithium bromide-water absorption refrigeration machines with single- and multi-stage processes of absorption and generation and with associated mass flow is carried out. The temperature influence analysis of the heating and cooling sources on the heat coefficient is performed. Parameters of external sources that allow implementation of these thermodynamic cycles are determined. Meanwhile, for cycles with two-stage absorption and generation processes, a heating source with temperature (20 ÷ 24)°C lower in comparison with the basic single-stage cycle, and for a cycle with three-stage processes – lower by (27 ÷ 30)°C is required. It has been established that with the accepted parameters of external sources, the actual coefficient of performance is within the limits: for a single-stage, lithium bromide-water absorption refrigeration machine (LBWARM) it is 0.68 ÷ 0.74, for a two-stage LBWARM, it is 0.36 ÷ 0.39 and for a three-stage LBWARM, it is 0.24 ÷ 0.26.

A detailed parametric study of a solar driven double-effect absorption chiller under various solar radiation data

Abstract This article presents simulation results of a solar cooling system that consists of a parallel-flow double-effect water-lithium bromide absorption chiller and parabolic trough solar collector. Parametric study of the cooling system is carried out considering a reference double-effect absorption chiller from Broad Company with nominal cooling capacity of 1163 kW. The aim for the analysis is to properly size the solar collector field and study the interaction of different operating conditions and parameters on the operation and performance of the system. Based on the operational constrains of the reference chiller, such as the minimum chilled water temperature and the cooling power, a solar collector field of 1350 m2 (1.16 m2/kW) is obtained from the range of 800–1800 m2. The reference system is then optimized where the exergy efficiency (second law efficiency) is maximized considering the flow rates of the external working fluid and solution distribution ratio of the parallel-flow double-effect absorption chiller as the decision variables. The system optimization is performed considering the risk of solution crystallization at various locations within the chiller. The optimum parameters together with other operating conditions are normalized per unit chiller nominal cooling capacity so that these values can be applied to other similar system configurations with different chiller nominal capacities. The reference system is simulated at optimum condition using a typical day climate data of Kuala Lumpur, Malaysia. The system achieved cooling effect in the range of 798–1223 kW under solar radiation levels of 600–944 W/m2. The procedure presented in this paper can be applied in sizing the solar collector field and evaluating the performance of similar systems under various climatic conditions having minimum solar radiation around 500 W/m2.

Thermodynamic and economic analysis of different cogeneration and trigeneration systems based on carbon dioxide vapor compression refrigeration systems

Carbon dioxide vapor compression refrigeration cycles operating at low evaporator temperatures represent a substantial waste energy recovery potential to generate useful products using the high-temperature carbon dioxide leaving the compressor. Despite this remarkable potential, there are limited investigations about waste energy recovery from these cycles for different applications. Using this as a motivation, in this work, different novel integrated cogeneration and trigeneration configurations are proposed based on a carbon dioxide parallel compression economization-vapor compression refrigeration cycle with a 1000 kW capacity and evaporator temperatures of −35 °C to −45 °C. The major originality of this work is the proposal and detailed techno-economic evaluation of several feasible cogeneration and trigeneration configurations for different practical applications. Different cycles and components are integrated into the carbon dioxide cycle including single and double stages water-lithium bromide absorption chillers, a single stage ammonia-water absorption refrigeration, a carbon dioxide-water heat exchanger and an organic Rankine cycle. The thermo-economic findings demonstrate that recovering the available thermal energy of carbon dioxide exiting the compressor would be very attractive both thermodynamically and economically to produce several useful outputs. More than 478 kW and 147 kW cooling (air conditioning) and refrigeration effects can be generated using the cogeneration configurations. Also, between 59.52 kW and 185.8 kW power can be generated depending on the configurations and organic fluid used, improving the coefficient of performance up to 18.0%. Moreover, 7763–9360 m3/year of domestic hot water can be generated by the trigeneration configurations, reducing the levelized cost of cooling up to 13%.

Energy and economic analysis of a solar-assisted multi-commodity cold storage

Most of the existing cold storages of the developing countries are dedicated toward storage of a single commodity due to which they remain underutilized for a considerable part of a year. In this paper, a conceptual design of multi-commodity cold storage has been discussed to store three high-value perishable commodities for different periods of a calendar year for round the year utilization of the cold storage facility. A cooling system based on the lithium bromide–water absorption system has been designed to maintain a favorable inside microclimate. A solar thermal–photovoltaic-based hybrid power system has been designed to meet the thermal and electrical loads of the system. The performance of the cold storage system has been analyzed using a thermal model for a complete calendar year for the climatic condition of Kolkata, India. A life-cycle cost analysis of the power system has also been carried out. The study revealed that the product load contributes toward 70% of the cooling load during the months of product loading. It is also observed that forty-six numbers of parabolic trough collectors along with two hundred seventy-five numbers of SPV modules of 150 Wp each can meet the major fraction of the load on an annual basis. The economic analysis revealed that the payback period of the integrated power system is only 6.22 years. The study thus reinforces the viability of solar-powered multi-commodity cold storages for the developing countries of the world both from the technical and economic point of view.

Investigations on water–LiBr‐based absorption refrigerator with solar parabolic dish in cogeneration mode

Here, performance of 11 kW solar-powered lithium bromide water absorption chillers in cogeneration mode is investigated. A 40 m 2 solar parabolic dish of 19 kW th capacity is used for both processes heating and cooling. Extensive thermodynamic design and analysis are carried out, and the results obtained are validated. Parabolic dish and cavity receiver are sized for Chennai (13°N, 80.18°E), India. In the present analysis, a new performance parameter COP WE is introduced by replacing the thermal input component in the calculation of COP, by an equivalent amount of high-grade energy. Both physical and chemical exergy at all state points of the chiller are estimated and found that total irreversibility is about 2.37 kW in desorber followed by absorber which is 0.41 kW. The developed model estimates solution concentration at the exit of solution expansion valve (SEV) that is important since it affects absorption of refrigerant in the absorber.

Optimization and dynamic analysis of a novel polygeneration system producing heat, cool and fresh water

This paper presents the integration of the evacuated tube solar collectors into a novel solar polygeneration plant. The analysis is performed by evaluating the energy and economic performance of the plant, coupled to a multi-effect distillation unit for seawater desalination, a single effect water lithium bromide absorption chiller, a biomass auxiliary heater, heat exchangers, tanks and balance-of-plant devices. Solar collectors produce heat, at about 90 °C, used for space heating and domestic hot water production, driving the absorption chiller (used for space cooling). Solar heat, combined the heat produced by the biomass auxiliary heater, also drives the multi-effect distillation unit producing desalinated water. The plant is simulated by means of a zero-dimensional dynamic model, developed in TRNSYS environment, which considers several control strategies, for the plant management. The economic analysis shows that the economic profitability significantly improves in case of feed-in tariffs, achieving a payback period of about 3.5 years. The optimization procedure performed by using the Design of Experiment method, returned a payback period of 2.4 years, by selecting the solar field area equal to 1200 m2, the tank dead band temperature to 2 °C, the summer/winter outlet set point temperature from the solar field equal to 95 °C/50 °C.

Optimization and comprehensive exergy-based analyses of a parallel flow double-effect water-lithium bromide absorption refrigeration system

In this paper, a parallel flow double-effect water-lithium bromide absorption refrigeration cycle is investigated using comprehensive exergy-based analyses. The exergy destruction of each device is calculated and used for further analysis. The performance of the system is optimized for maximum coefficient of performance and exergy efficiency, considering the distribution ratio as a variable using the Golden Section method. The maximum coefficient of performance, i.e. 1.295, is obtained at a high pressure generator temperature of 169.6 °C, and the maximum exergy efficiency, i.e. 0.225, is obtained at a high pressure generator temperature of 142.7 °C. Advanced exergy analysis, a state of the art thermodynamic method, is employed for diagnosing equipment and cycle malfunctions. Not only can the aforementioned analysis pinpoint the source of irreversibility, it also provides the avoidable irreversibility as well. The results show that the endogenous part of the exergy destruction is much larger than the exogenous part, implying it is better to focus on component efficiencies to improve system performance. Moreover, the unavoidable part of the total exergy destruction is much larger than the avoidable portion, indicating that exergy destruction cannot be decreased owing to technical limitations of equipment.

Comments on “Multi-objective optimization of double effect series and parallel flow water–lithium chloride and water–lithium bromide absorption refrigeration systems” by Konwar et al. [Energy Convers. Manage. 180 (2019) 425–441

The paper, “Multi-objective optimization of double effect series and parallel flow water–lithium chloride and water–lithium bromide absorption refrigeration systems” by Konwar et al. [Energy Convers. Manage. 180 (2019) 425–441], presented a genetic algorithm based multi-objective optimization tool along with its applications, which are found highly erroneous and conveying wrong information. Such issues are explained here in detail in order to prevent readers from misleading.

Reply to Comment on Multi-objective optimization of double effect series and parallel flow water-lithium chloride and water-lithium bromide absorption refrigeration systems“ [Energy Convers. Manage. 2019;180:425–441] by Konwar et al.

Reply to Comment on Multi-objective optimization of double effect series and parallel flow water-lithium chloride and water-lithium bromide absorption refrigeration systems“ [Energy Convers. Manage. 2019;180:425–441] by Konwar et al.

The development and assessment of solar-driven Tri-generation system energy and optimization of criteria comparison

In this research, the thermodynamic investigation of the tri-generation system is performed by the first and second law of Thermodynamics. The trigeneration system under study consists of three subsystems including the solar subsystem, Kalina subsystem and lithium bromide-water absorption chiller subsystem. The proposed system generates power, cooling and hot water using solar energy. The system considered is designed and evaluated based on the climate condition in Zahedan, Iran. The calculation results show that the most exergy destruction rate takes place in the solar cycle. The assessment of system is used dynamic and static forms. In dynamic form, that maximum total cost rate, energy and exergy efficiency are equal to 15.1 dollars per hour,by 33% and 36.47%, respectively. The results base-case demonstrate that energy and exergy efficiencies and total cost rates are equal to 9.63 dollars per hour by 17.37% and 18.82% , respectively in static analysis. Furthermore, optimization criteria comparison such as energy efficiency, exergy efficiency and power are discussed in static form. The results of static evaluation revealed that the power is the best criteria for thermodynamics. Moreover, optimization results based on maximum power criterion show that produced power, energy efficiency, exergy efficiency and total cost rate increase by 28%, 12.32%, of 13.97% and 7.68%, respectively in comparison with the base case.

Multi-objective optimization of double effect series and parallel flow water–lithium chloride and water–lithium bromide absorption refrigeration systems

In this study, multi-objective optimization of the series and parallel flow type double effect absorption refrigeration systems is presented. Genetic algorithm is used to find the optimal solutions and the Pareto-optimal fronts. First, a thermodynamic model is developed to simulate the double effect series and parallel flow configurations with water–lithium chloride and water–lithium bromide solution pairs. Energy and exergy balances are applied to evaluate coefficient of performance, exergy efficiency and irreversible losses in the system components separately for the two working fluid pairs. Next, optimization is done considering coefficient of performance, exergy efficiency and the total system irreversibility rate as objective functions. The low and high pressure generator temperatures are taken as decision variables in the series configuration while for the parallel system; additionally the distribution ratio is also taken as a decision parameter. The optimization is done for four different cases of fixed evaporator, absorber and condenser temperatures. For each case, the optimal decision parameter values are determined for both the water–lithium chloride and water–lithium bromide operated double effect series and parallel configurations. The optimized coefficients of performance were found slightly lower for water–lithium chloride. Contrary to this, the optimal exergy efficiencies were more and the total system irreversibility were less for water–lithium chloride. Further, the optimal performances of the double effect water–lithium chloride systems were obtained comparatively at lower generator temperatures than those of the water–lithium bromide systems.

Performance analysis and optimization of new double effect lithium bromide–water absorption chiller with series and parallel flows

In this paper the effect of some key parameters on coefficient of performance (COP) in two novel arrangements of double effect lithium bromide–water absorption chillers with series and parallel flow have been studied. The main components of these cycles are generators, absorber, condensers, evaporator and heat exchangers. The mass, concentration, and energy balance equations are used for both cycles and performances of the systems are analyzed at different conditions with the condition of no formation of lithium bromide crystal. Also, the effects of temperatures and mass flow rates of inlet vapor of generator and inlet water of absorber on evaporator cooling capacity, absorber heat transfer rate and COP are investigated. In addition, two new parameters based on mass ratio of solution splitters are defined (R1 and R2) and their effects on the system performance are analyzed. The results show that the series cycle at inlet vapor temperature to the high temperature generator (HTG) below 150 °C has higher COP than the parallel cycle. In addition, with increase of inlet vapor temperature to HTG and rise of mass flow rate of inlet water to absorber, the COP increases in both parallel and series cycles. In addition, with increase of R1, the COP increases at first and reaches to a maximum value, and then decreases. Furthermore, the Genetic Algorithm (GA) method has been used to optimization of the system COP at series and parallel cycles.