Double-effect Absorption Chiller Research Articles

Performance enhancement and multi-objective optimization of a solar-driven setup with storage process using an innovative modification

The main objective of this study is to propose and design a novel modification process of a combined cooling, heating, and power production setup using parabolic trough solar collectors, contributing a higher performance. The base setup consists of a solar subsystem, an organic Rankine cycle for electricity generation, a heat exchanger and a single-effect absorption chiller that produce heating and cooling utilizing the organic Rankine cycle waste heat. The base setup is modified by adding two regenerative organic Rankine cycles, three heating process heat exchangers, and a double-effect absorption chiller. Both systems are studied and compared in three different modes, embracing solar mode (low radiation), solar and storage mode (high radiation), and storage mode (no radiation). Compared to the base setup, for the modified system, electricity production improves by 10.4%, 18.4% and 3.0% in the aforementioned operational modes, respectively. Also, for these modes, the electrical efficiency of the modified system is found to be 1.4 percent-point, 0.9 percent-point, and 0.3 percent-point higher than those of the base one, correspondingly. Eventually, a multi-objective optimization is conducted to optimize the modified system using a genetic algorithm.

The use of waste heat recovery (WHR) options to produce electricity, heating, cooling, and freshwater for residential buildings

In recent years, there is a growing attention drawn to the area of building-integrated CCHP systems, due to its high capability in cost and energy saving. In this study, a residential scale multigenerational system is proposed to generate power by using solid oxide fuel cell and gas turbine (hybrid SOFC/GT), heating (by using HRSG), cooling (by using a double-effect absorption chiller) and freshwater (by using a Revers osmose plant). The system is modeled in engineering equation solver and studied from energy, exergy, economic and environmental standpoints. A parametric study is conducted in order to define the crucial decision variables in the system, and their effect on the overall exergy efficiency and unit product cost, along with the rate of freshwater production is observed. Results of the parametric study demonstrated that fuel utilization factor, stack temperature difference, current density, and the pressure ratio of air compressor have the most substantial influence on the behavior of the proposed system. Moreover, obtained results revealed that the energy and exergy efficiency of the system reaches 86.32% and 69.06%, respectively. In addition, the rate of freshwater production and unit product cost of the entire system becomes 256 L/day and 37.78 $/GJ.hr. Furthermore, the emission of the proposed system becomes 0.225 ton/MW.hr, which faces a 31% reduction compared to the standalone power generation system.

Design parameters and dynamic performance analysis of a high efficient solar-ground source cooling system using parabolic trough collector

ABSTRACT This paper takes the independent-developed special parabolic trough collector for the air-conditioning and the double-effect absorption chiller to build a solar cooling system, and simultaneously utilizes the ground heat exchanger(so-called SGAC system) to replace the traditional cooling tower as the heat exhausted side(so-called SAC system) in summer. The simulation model of SGAC is established on TRNSYS. The simulation calculation is performed for the building cooling during the whole cooling season in Beijing. The research results indicate that SGAC has a good stability and high efficiency during the whole cooling season. The performance comparison of SGAC and SAC has been carried out. The economy of SGAC system should also be considered in the determination of the main design and operating parameters.

Energy, exergy, exergo-economic and exergo-environmental analyses of solar based hydrogen generation system

The present study focuses on the energy, exergy, exergo-economic, and exergo-environmental analyses of the solar-assisted multi-generation system. The multi-generation system consists of parabolic trough solar collector, regenerative power plant, double-effect absorption chiller system, proton exchange membrane electrolyzer, and multi-stage flash desalination plant. In the regenerative power plant, liquid petroleum gas (LPG) based boiler is implemented. The propane (C3H8) is used as the fuel in the boiler combustion chamber. The thermal and exergetic efficiencies of the power cycle are observed to be 41.08% and 23.26%, respectively. The electrical power of 1.384 MW is produced by the low-pressure turbine. Whereas, the thermal COP and exergetic COP are observed and maintained in the range of 1.28 to 0.22, respectively. The liquid hydrogen is produced by the PEM electrolyzer with the thermal and exergetic efficiencies of 60.83% and 64.65%, respectively. Furthermore, the exergo-economics and exergo-environmental analyses have also been conducted and all the parameters have been analyzed and concluded through graphs and tables.

A novel multi-objective spiral optimization algorithm for an innovative solar/biomass-based multi-generation energy system: 3E analyses, and optimization algorithms comparison

A novel multi-generation energy system is proposed consisting of a solar gas turbine system, multi-effect seawater desalination, LNG cold energy recovery unit, and a double effect absorption chiller. In addition, different working fluids of the ORC system are examined to select the suitable working fluid in terms of global warming potential and exergy efficiency of the system. Subsequently, energy, exergy, and economic (3E) analyses are performed to comprehensively evaluate the energy system. Besides, a parametric study is conducted to assess the effect of the most influential decision variables on the proposed system. Afterward, the novel multi-objective spiral optimization (MOSPO) algorithm is introduced to minimize total cost rate of the system while maximizing the exergy efficiency as the conflicting objective functions. The proposed algorithm is developed to optimize the decision variables effectively. To ascertain the final optimum solution point, three conventional methods i.e. TOPSIS, LINMAP and Shannon’s entropy are implemented. The results revealed that exergy efficiency and total cost rate of the system at the baseline are 60.05%, and 36.75 $/h, respectively. Furthermore, the net power output of the system would be 106.5 kW in addition to 0.7703 kW heating load, 56.01 kW cooling capacity, and 35.74 kg/h fresh water production capacity. The eco-environmental assessment revealed the fact that the proposed renewable-based energy system is capable of avoiding 485 tons CO2 emissions annually, and product cost rate reduction up to 6 $/hr in comparison to coal and natural gas-based energy systems. Besides, the proposed MOSPO algorithm is compared with common optimization methods; accordingly, the conventional algorithms are selected for the comparison including non-dominated sorting genetic algorithm II (NSGA-II), the multiple objective particle swarm optimization (MOPSO) algorithm, the Pareto envelope-based selection algorithm II (PESA-II), and the strength Pareto evolutionary algorithm II (SPEA-II). The comparison results show that the proposed MOSPO algorithm is preferable according to the Taylor Diagrams showing the performance of the algorithms.

Energy and exergy analysis of a new combined concentrating solar collector, solid oxide fuel cell, and steam turbine CCHP system

In the present study, energy, exergy and thermodynamic analysis of a novel integrated system in form of combined cooling heating and power process is investigated. The proposed system consists of solid oxide fuel cell to produce electrical and thermal power, steam power turbine to generate additional electrical power, concentrating solar collector to provide a part of the process thermal energy and double effect absorption chiller to provide cooling demand. In this process, the fuel cell’s high temperature exhaust gases are used to run the absorption chiller. In addition, the concentrating solar collector is a kind of parabolic trough solar collector that acts as a heat exchanger. In order to evaluate the solar field performance, the climates of the three cities in Iran are considered. The results showed acceptable values for system efficiency and overall performance. Finally, the sensitivity analysis of the various components of the process such as fuel cell, steam turbine, solar collector and air compressor and the effect of input fuel and oxidation flow are presented to investigate their impact on the performance of the proposed process.

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.

Thermodynamic analysis and multi-objective optimization of a new biomass-driven multi-generation system for zero energy buildings

The current study presents and evaluates a new biomass-driven multi-generation system for zero energy building (ZEB) purpose. The system is aimed at providing a sample building’s electric power, hot water, heating, and cooling requirements throughout the year. The presented system is comprised of a biomass gasifier, an internal combustion engine, a water-lithium bromide double-effect absorption chiller, a backup boiler for hot water production, gas and hot water storage tanks, and heat exchangers. After introducing a pair of objective functions (namely, annual actual benefit, and loss of building requirements supply probability), the proposed system is optimized by using the modified non-dominated sorting Genetic Algorithm (NSGA-II). The results reveal that the proposed system is able to fully satisfy the building’s requirements and reach ZEB goal with the levelized cost of energy (LCOE) of about 0.19 $/kWh. A cost breakdown analysis shows that the highest and the lowest costs of the system are related to the purchase of the internal combustion engine (about 50% of total cost) and the purchase of heat exchangers (about 1% of total cost), respectively. Furthermore, a comprehensive sensitivity analysis is carried out to figure out the influence of some major economic factors on the systems annual benefit and LCOE. This analysis identifies generated electricity price conversion factors as the most influential parameters, and buying electricity cost as the least influential factor.

A novel solar system integrating concentrating photovoltaic thermal collectors and variable effect absorption chiller for flexible co-generation of electricity and cooling

Traditional single effect and double effect absorption chillers have relatively narrow working temperature ranges, which limits their application of solar systems. This study proposes a novel solar system integrating concentrating photovoltaic and thermal collectors, and a variable effect absorption chiller, for more flexible and efficient co-generation of electricity and cooling. In this study, variable effect chiller was optimized, showing that three working modes, combined with optimized control, make variable effect chillers a superior choice to the single effect and double effect types. Then, dynamic simulations of the solar co-generation system were performed, in order to study the effects of temperature control on system performance. The results showed that, a high turn-off temperature for the chiller generally results in higher cooling power, shorter working hours for the chiller, and in some cases, a frequent on–off cycling of chiller. With the increase in working temperature level, the cooling exergy efficiency increases, but total exergy efficiency decreases due to the photovoltaic cell’s degraded performance. The total exergy efficiency is approximately 32%–33%. A larger difference between turn-on and turn-off temperatures delays the start time of the chiller while ensuring the full use of solar energy. By adjusting the temperature control strategy, the novel solar co-generation system can offer a cooling-electricity ratio from 1.4 to 2.0, which is capable of meeting the demands in many cases. The proposed system offers flexible co-generation of cooling and electricity.

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.

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.

New configurations of district heating and cooling system based on absorption and compression chillers driven by waste heat of flue gas from coke ovens

To recover waste heat for space heating and cooling, three new district heating and cooling systems based on absorption and compression chillers driven by waste heat of flue gas from coke ovens are proposed, and their significant differences are located in the energy station. The energy station of the first proposed scheme mainly consists of a double-effect absorption chiller, a single-effect absorption chiller, a water-to-water plate heat exchanger, a compression chiller for ice thermal energy storage, and a liquid desiccant regenerator. Compared with the first proposed scheme, the second proposed scheme has no liquid desiccant regenerator in the energy station. Compared with the second proposed scheme, the third proposed scheme has no single-effect absorption chiller in the energy station. The three proposed schemes are analyzed from the perspective of thermodynamic performance and financial benefit. The results show that among the three proposed schemes, the first proposed scheme has the highest thermodynamic performance, and the best financial benefit, and thus its configuration is optimal. The annual system coefficient of performance and annual product exergy efficiency of the first proposed scheme are about 19.8 and 44.1%, and its cost-effective transportation distance of waste heat can be up to 41.5 km.

Development of a novel flow control system with arduino microcontroller embedded in double effect absorption chillers using the LiBr/H2O pair

The purpose of this work is the development and implementation of a flow control strategy for the LiBr/H2O saline recirculation system in double effect absorption chillers to guarantee an optimum operating range. The control strategy was developed using the PID (Proportional-Integral-Derivative) controller hosted on the Arduino prototyping platform. Structural aspects of the double-effect absorption chiller as well as updating the thermophysical properties of the solution LiBr/H2O in real time to better suit the operation of the absorption cooling system were also considered. The proposed strategy enables a low-cost embedded system for gauging, controlling flow and maintaining optimal operating conditions. An experimental analysis was performed using initially pure water for calibration and control strategy testing, followed by the LiBr/H2O solution to show its versatility and operating accuracy in refrigeration absorption chiller. As a main result, the proposed system offers control of flow rates with a resolution of 0.60 L/min for 67% of the flow range provided by the conventional magnetic centrifugal pump recirculation system.

Introducing an integrated SOFC, linear Fresnel solar field, Stirling engine and steam turbine combined cooling, heating and power process

A new integrated combined cooling, heating and power system which includes a solid oxide fuel cell, Stirling engine, steam turbine, linear Fresnel solar field and double effect absorption chiller is introduced and investigated from energy, exergy and thermodynamic viewpoints. In this process, produced electrical power by the fuel cell and steam turbines is 6971.8 kW. Stirling engine uses fuel cell waste heat and produces 656 kW power. In addition, absorption chiller is driven by waste heat of the Stirling engine and generates 2118.8 kW of cooling load. Linear Fresnel solar field produces 961.7 kW of thermal power as a heat exchanger. The results indicate that, electrical, energy and exergy efficiencies and total exergy destruction of the proposed system are 49.7%, 67.5%, 55.6% and 12560 kW, respectively. Finally, sensitivity analysis to investigate effect of the different parameters such as flow rate of inputs, outlet pressure of the components and temperature changes of the solar system on the hybrid system performance is also done.

Energy Analysis for the Solar Thermal Cooling System in Universitas Indonesia

The objective of this study is to analyze all the energy used in the solar cooling system in Universitas Indonesia. This system uses three energies at the same time, namely, solar, gas and electricity energies, which are used to provide a required cooling capacity from the mechanical research center (MRC) building in Universitas Indonesia. The single–double-effect absorption chiller is the main component of the solar thermal cooling system to provide the chilled water that is circulated between the system and MRC building. In this system, heat from solar energy is absorbed by the evacuated tube solar collector and then transferred to the hot water that is used to generate vapor together with the gas at the absorption machine. On the other hand, electricity is mostly consumed by the pumps to circulate the hot, cooling and chilled water, also the working fluids inside the absorption machine. Finally, all the energies used to create a thermal comfort zone in the MRC building based on the Indonesia weathers are reported in this paper.

Mathematical modeling and performance analysis of an integrated solar heating and cooling system driven by parabolic trough collector and double-effect absorption chiller

With the increasing concerns on energy conservation and environmental protection, solar heating and cooling (SHC) system represents an attractive candidate in building sector. In this paper, an integrated SHC system driven by parabolic trough collector (PTC) and double-effect H2O/LiBr absorption chiller was presented. The energy generated by solar collectors was supplied to the absorption chiller during the cooling period, and was directly used for space heating with the integration of plate heat exchanger during the heating period. The mathematical models of the whole system including the collector, the double-effect absorption chiller and the plate heat exchanger were established and were validated by field tests. Based on the proposed models, comparison of the SHC system and the conventional gas-driven absorption heating and cooling system was carried out by case study. The annual performances as well as energetic, economic and environmental assessments of the proposed system were investigated. Results show that, 21.3% of the primary energy consumption and 18.8% of the CO2 emission can be reduced in SHC system. Therefore, the proposed integrated solar heating and cooling system has a promising application prospect in sustainable development in view of its considerable energy saving benefits, potential economic viability and environmental friendly characteristics.

Optimization of a novel solar-based multi-generation system for waste heat recovery in a cement plant

Abstract This article presents a novel renewable-based multi-generation energy system. The system is based on a double effect absorption chiller, an ejector refrigeration cycle, a proton exchange membrane electrolyzer, an amine-based CO2 capture system, an organic Rankine cycle, and a heater. The proposed integrated system is fueled by a biomass combustor, a photovoltaic thermal solar panels, and a waste heat recovery from a cement plant located in Abyek, Iran. This innovative configuration of energy system can produce electricity, cooling, heating, and hydrogen in summer and winter modes, in addition to removing CO2 from the flue gas of the cement plant. The system is analyzed in energetic, exergetic and thermoeconomic terms. The performance of the system is investigated parametrically by examining the effect of variation of selected key parameters. To perform comprehensive modeling, the system is assessed thermoeconomically through estimating unit cost of each product and total cost rate of the product. Finally, single and multi-objective optimizations are performed by an evolutionary algorithm and illustrated on a Pareto frontier in order to achieve the optimum scheme of the multi-generation system regarding technical and economic viewpoints. According to the results, the studied integrated system produces 17.4 MW and 18.4 MW electricity in summer and winter, 4.1 MW heating power, 1.2 MW cooling power, 5.8 kg/h and 11.3 kg/h hydrogen in summer and winter. Moreover, the system captures 234.1 kg/s CO2 with 90% removal factor from the cement plant. The result of the optimization indicates in winter product cost rate of the Combined Cooling, Heating and Power (CCHP) subsection can reduce 24%. However, in summer for a 0.47% increase in product cost rate, the exergy efficiency is capable of increase by 39%.

Assessment and multi-criteria optimization of a solar and biomass-based multi-generation system: Thermodynamic, exergoeconomic and exergoenvironmental aspects

In the present work, a new design of a multi-generation system based on biomass and solar energy with the purpose of generating electric power, heating, cooling, hydrogen, and potable water is introduced. The system comprises a steam Rankine cycle, double effect absorption chiller, proton exchange membrane electrolyzer, multi-effect desalination, and parabolic trough solar collector. A thermodynamic analysis is carried out to present the thermodynamic feasibility and deficiencies by calculating the irreversibilities occurring in the components. Exergoeconomic modeling yields the product cost rate of different products and cost flow in the studied system. Also in order to determine the amount of environmental effect of the suggested system, the exergoenvironmental study is performed and discussed. Results demonstrate that energy efficiency, exergy efficiency, total product cost rate and exergoenvironmental impact improvement of 82.4%, 14%, 0.84 $/s and 0.15 are achievable for the multi-generation system respectively. Finally, multi-criteria optimization approach based on a genetic algorithm is applied to specify the optimum design of the system considering the improvement of thermodynamic and thermoeconomic performance. By extracting the Pareto frontier, a design scheme related to exergy efficiency of 16.53% and product cost rate of 0.71 $/s is selected as an optimal design.

The study of a seasonal solar CCHP system based on evacuated flat-plate collectors and organic Rankine cycle

The demands of cooling, heating and electricity in residential buildings are varied with seasons. This article presented a seasonal solar combined cooling heating and power (CCHP) system based on evacuated flat-plate collectors and organic Rankine cycle. The heat collected by evacuated flat-plate collectors is used to drive the organic Rankine cycle unit in spring, autumn and winter, and drive the double-effect lithium bromide absorption chiller in summer. The organic Rankine cycle condensation heat is used to yield hot water in spring and autumn, whereas supply heating in winter. The system thermodynamic performance was analyzed. The results show that the system thermal efficiency in spring, autumn and winter, ?sys,I, increases as organic Rankine cycle evaporation temperature, T6, and evacuated flat-plate collectors outlet temperature, T2, decrease. The maximum ?sys,I of 67.0% is achieved when T6 = 80?C and T2 =100?C. In summer, the system thermal efficiency, ?sys,II, increases first and then decreases with the increment of T2. The maximum ?sys,II of 69.9% is obtained at T2 =136?C. The system output performance in Beijing and Lanzhou is better than that in Hefei. The average output power, heating capacity, hot water and cooling capacity are 50-72 kWh per day, 989-1514 kWh per day, 49-57 ton per day and 1812-2311 kWh per day, respectively. The system exergy efficiency increases from 17.8-40.8% after integrating the organic Rankine cycle unit.

Thermodynamic diagnosis of a novel solar-biomass based multi-generation system including potable water and hydrogen production

In this study, a new proposed multi-generation system as a promising integrated energy conversion system is studied, and its performance is investigated thermodynamically. The system equipped with parabolic trough collectors and biomass combustor to generate electricity, heating and cooling loads, hydrogen and potable water. A double effect absorption chiller to provide cooling demand, a proton exchange membrane electrolyzer to split water into hydrogen and oxygen and a multi-effect desalination system to provide potable water by recovering the waste heat of biomass combustion is combined with a steam Rankine cycle. The results of the thermodynamic analysis indicate that thermal efficiency of 82.5% and exergy efficiency of 14.6% is achievable for the proposed system. Hydrogen and potable water production rates are 88.1 kg/h and 3.9 m3/h, respectively. The proposed system generates 26.3 MW electricity, 26.3 MW heating load, and 137.2 MW cooling load. Parabolic trough solar collector, double effect absorption chiller and biomass combustor are the primary sources of thermodynamic irreversibilities in comparison to other components. The mass flow rate of biomass fed to the system and aperture area of parabolic trough solar collector is calculated to be 6.2 ton/h and 188,000 m2. Besides conventional analyses, to conclude the concept of multiplicity six different cases for the studied multi-generation system are modeled and evaluated regarding thermal and exergy efficiencies. Finally, the parametric study is performed to identify the consequential parameters on the thermodynamic performance of the system.