Absorption Refrigeration Unit Research Articles

Thermodynamic analysis of a hybrid ammonia-water refrigeration cycle with low-temperature solar heat

The performance of a solar-driven single-effect ammonia absorption refrigeration unit was studied numerically and experimentally. The thermal performance and unit operation status of small refrigerators were studied under various designing and operating conditions. A thermodynamic cycle scheme of hybrid ammonia-water refrigeration (HAWR) is proposed to operate in parallel with the compressor and ammonia absorption refrigeration, and the performance of the thermodynamic circulation system is evaluated by considering the thermodynamic coefficient and thermodynamic refrigeration ratio as evaluation indexes. Aspen Plus simulation software was introduced to simulate the HAWR and optimise the operation strategy. The results indicate that adjusting the compressor outlet pressure can stabilise the refrigeration capacity of the ammonia refrigeration system. The optimised working point pressure is 600 kPa, while the corresponding evaporation, condensation, absorption, and generation temperatures are 15 °C, 40 °C, 42 °C, and 85 °C respectively, the thermodynamic coefficient is 0.307, and the thermodynamic refrigeration ratio is 0.443. Under the rated cooling conditions, 44.3 % of the cooling capacity is driven by solar energy, and 55.7 % is driven by electric energy in the optimal working state. Under non-optimal working conditions, the proportion of the cooling capacity driven by electric energy is as high as 79.5 %. Under the conditions of sunny weather and with the absence of the compressor, the cooling capacity increases from 2.5 to 7.5 kW as the radiation intensity increases from 600 to 950 W/m2, while the system performance tends to be stable and the coefficient of performance maintains around 0.738 as the irradiation intensity exceeds 800 W/m2.

Proposal of a geothermal-driven multigeneration system for power, cooling, and fresh water: Thermoeconomic assessment and optimization

The depletion of fossil fuel reserves and environmental challenges have prompted the exploration of alternative energy sources. Geothermal energy, extractable from within the Earth's crust, emerges as a reliable renewable option throughout the mentioned shift. In this regard, the presented study introduces a geothermal-powered multigeneration system designed to generate power, manage cooling loads, and produce fresh water. This comprehensive system incorporates an organic flash cycle, a half-effect absorption refrigeration unit, a Kalina cycle, and a humidification-dehumidification desalination unit. Evaluating the system's thermoeconomic performance involves considering input parameters and simplifying assumptions to determine the performance profitability of the presented system. Furthermore, a parametric examination is conducted which is followed by the employment of an optimization analysis across three diverse scenarios to identify the most favorable operating conditions. The results of the presented research reveal that the suggested system can deliver power, cooling capacity, and freshwater production at rates of 342.3 kW, 301.7 kW, and 0.233 kg/s, respectively. Additionally, the system demonstrates an exergy efficiency of 31.52 % and achieves a payback period of 5.85 years.

Designing energy-efficient hardware and technological structure of absorption refrigeration units for ammonia production

The object of research is the equipment and technological design of absorption refrigeration units (ARUs) for the technological system of secondary condensation of large-scale ammonia production. Improving the energy efficiency of ARU is an urgent problem in the general process of reducing operating costs for natural gas in these industries as a whole. Based on the results of analytical studies, the feasibility of combining absorption-refrigeration and vapor-ejector cycles was substantiated, which ensures a decrease in the boiling temperature of a weak water-ammonia solution in the cube of the generator-rectifier and an increase in the condensation pressure in the ARU cycle. Under such circumstances, it becomes possible to increase the concentration of the refrigerant due to the rectification of steam with a part of the liquid refrigerant without using a pump with the removal of the dephlegmator from the ARU circuit. Experimental studies and material-thermal calculations of ARU cycles were carried out to determine the basis of comparison and the proposed version of the ARU scheme. It has been proven that the new technological design of ARU provides an increase in cooling capacity from 3.22 MW to 3.6 MW (by 12 %), the thermal coefficient from 0.527 to 0.551 (by 4.6 %), a decrease in the circulation ratio from 7.77 to 7.1 (by 8 %), and a decrease in the secondary condensation temperature by 2.5 ℃. It is shown that for the proposed version of the technological design of ARU, there is a change in specific costs – an increase in electricity by 1.48 kWh/t NH3 and a decrease in natural gas by 0.41 nm3/t NH3. Taking into account existing cost indicators for natural gas and electricity, the application of the proposed technology ensures a decrease in annual operating costs by UAH 7 million (USD 185,000), and therefore an increase in the economy of ammonia production as a whole

Prospects for the use of a membrane refrigeration unit for the production of cold as an alternative to absorption

Objective. The purpose of the study is to determine the prospects for using a membrane refrigeration unit for the production of cold as an alternative to absorption. Method. The study was carried out using a numerical experiment and verification of the results obtained on an experimental bench. Result. An analysis was made of the use of a traditional absorption refrigeration machine and a membrane refrigeration machine from the point of view of energy efficiency and the number of working elements. Presented for comparison are methods for calculating the separation process of the “absorbent-refrigerant” mixture based on reverse osmosis processes and a water-ammonia absorption refrigeration unit. Conclusion. The use of separation processes in membrane apparatuses for the production of cold in mixed refrigeration machines, as an alternative to absorption refrigeration machines, will ensure a more stable process for obtaining refrigerant from the mixture, reduce material costs for the production of a refrigeration unit and increase the energy efficiency of a refrigeration unit operating on mixed components.

Analysis of the possibilities of increasing the energy efficiency of absorption refrigeration appliances through the use of refrigerating accumulators

One of the most important tasks of modern society is the solution of environmental and energy problems in power engineering and, in particular, refrigeration technology. At the same time, in the field of artificial cooling systems, it is necessary to solve the problems of reducing the impact on both the ozone layer and the greenhouse effect. An effective approach here can be absorption refrigeration systems with a natural working fluid (water-ammonia solution), which does not adversely affect the environment. For the effective use of absorption refrigeration systems, it is necessary to solve the problems of increasing their energy efficiency, in particular, through the use of cold accumulators. Thus, the object of research is absorption-type cooling systems with cold accumulators.
 The paper analyzes cold accumulators with different physical nature. It is shown that melting substances can be the most effective for solving problems of low-temperature cooling. An analysis of the thermal scheme of an absorption freezer of the «chest» type, which is the most problematic in terms of providing cooling modes at a level of (–18)–(–24) °С, was carried out. Optimization thermal calculations for typical absorption freezers up to 200 dm3 have been performed. It is shown that when the chamber is initially loaded with a product at an ambient temperature, the cooling capacity of the installed absorption refrigeration units is not enough – no more than 50 % of the required one. For an absorption freezer of the «chest» type, the most suitable cold-storage materials are a eutectic aqueous solution of sodium chloride or propylene glycol, since these solutions have the desired melting point of the order of –18 °C and a fairly high melting heat. The result of optimizing the weight and size characteristics of the internal volume of the absorption freezer is the following recommendations:
 – the optimal size of wire baskets for placing products is 315´370´240 mm;
 – the gaps between the basket and the cabinet wall, as well as between the baskets themselves, should be 10 mm to ensure normal convection conditions;
 – it is not advisable to place fans inside the volume of the freezer at this stage, since the freezing time is reduced by a maximum of 30 %, but this results in additional heat generation, energy consumption and increases the shrinkage of the products stored in the chamber.

Gas turbine-based system taking advantage of LNG regasification process for multigeneration purposes; Techno-economic-environmental analysis and machine learning optimization

It is viable for engineers to determine how thermodynamic systems can benefit from heat recovery in order to improve efficiency, reduce costs, and lower carbon dioxide emissions. The authors of the study propose a new energy system that incorporates various cycles and units, including gas turbines, Rankine and two organic Rankine cycles, an absorption refrigeration unit, a proton exchange membrane (PEM) electrolyzer, and a liquefied natural gas (LNG) unit. The hydrogen produced is stored and transferred for use as fuel. The system was modeled and optimized using MATLAB programming software, with a parametric study and sensitivity analysis conducted before employing a genetic algorithm optimization to find the most suitable performance conditions. Modifying the compressor's pressure ratio within the range of 6–18 caused a shift in the cooling load, ranging from 45 to 36 MW. Nonetheless, these adjustments in pressure ratio yielded a reduction of 0.4 Cent/kWh in levelized cost of electricity (LCOE) and 0.15 $/kg in levelized cost of hydrogen (LCOH). In the base design mode, the total cost rate is 5715.3 $/h, the exergy efficiency is 39.03%, and the normalized CO2 emissions are 335.89 kg/GJ. However, the optimization results showed a reduced total cost rate of 1884.50 $/h, along with an improved exergy efficiency from 39.03% to 40.32% and a decrease in annual CO2 emissions from 211,000 metric tons to 175,000 metric tons. The implementation of artificial neural networks (ANN) has significantly decreased the time required for optimization from 47 h to just 16 min.

Case study: Design of an absorption refrigeration system for milk preservation in Jalisco, Mexico

This article presents a case study focused on designing a refrigeration system for milk storage in a town of Jalisco, Mexico. An absorption refrigeration unit is proposed, activated with a geothermal heat source from an existing well. An economic analysis of the proposal and its comparison with a conventional system and a solar system is presented. The proposed system must provide refrigeration to the warehouse (cold room) with a cooling load of 5 kW, with a geothermal heat source temperature of 80 °C for the single effect system and 163 °C for the double effect system. For the design of the warehouse, the thermal loads were obtained through ceilings and walls, by lighting, infiltration, and by occupation, through the EnergyPlus software. The results show values of monthly thermal loads ranging between 0.94 and 1.1 kW. The single-effect system achieved a COP of 0.85 costing approximately $13,083, while the double-effect system reached a COP of 1.38 with a cost of $18,144.

Development of a new type of household appliances – refrigerators with a heating chamber

The object of this study is absorption-type refrigeration appliances, which allow to expand the functionality of household appliances without additional energy consumption.
 Investigated problem: The aim of this study: firstly, due to the novelty of the proposed technique, it was necessary to show the real possibility of obtaining the temperature level required for technological processes (up to 70 °C); secondly, taking into account the experience gained in experimental studies, it was necessary to propose new designs for solving the problems of refrigeration and heat treatment of food products and raw materials in domestic conditions.
 The main scientific results: It is shown that the development of devices that combine the functions of refrigeration storage and heat treatment of food products, semi-finished products and agricultural raw materials can become a promising area for energy saving in household appliances. In such household combined appliances, the heat released during the implementation of the refrigeration cycle is not immediately removed to the environment, but is transferred to a special heating chamber, while the temperature in the volume of the heating chamber is maintained higher than the air temperature in the room. The effect of energy saving is achieved by expanding the functionality of household appliances without attracting additional energy costs.
 The original designs of combined absorption-type household appliances are proposed, a description of their operation, advantages and disadvantages, and areas of application are given.
 The area of practical use of the research results: In the course of experimental studies, it was shown that the introduction of an additional heating chamber into the structure of household absorption refrigerators, thermally connected with the lifting section by the dephlegmator of the absorption refrigeration unit, does not lead to an increase in energy consumption (according to the test results below than in the standard version by 5 %) and does not impair the performance of the cooling chambers.
 The area of practical use of the research results: household energy-saving appliances.
 Innovative technological product: the use of an evaporation-condensation cycle that provides highly efficient heat transfer at a distance of up to 1 meter from the heat dissipation zone of the refrigeration unit to the usable volume of the heating chamber of the household appliance.

Analysis of the Energy Efficiency of the Air Conditioning System Based on Absorption Refrigeration Machine with Connection of Heat Pump and Solar Collectors

This article proposes and analyzes a circuit solution for providing heat supply to the generator of an absorption refrigeration machine (AHM) in centralized air conditioning systems using a heat pump unit (HPU) and solar collectors (SOL). Previously, such schemes have already been considered in the scientific works of Russian and foreign authors. The aim of the work is to propose new circuit solutions aimed at improving such systems, as well as confirming higher energy efficiency. This goal is achieved by solving the following problems: additional supply of the circuit with a common storage tank, operation of the absorption refrigeration machine generator and the condenser of the heat pump unit based on a common heat exchanger. Such a solution for the air conditioning complex based on an absorption refrigeration unit has been proposed for the first time. The most important results are the possibility of obtaining high values of the coefficient of performance, the possibility of achieving a number of technological advantages, increasing reliability and efficiency, as well as reducing the metal consumption of an absorption-type plant operating from solar collectors and a heat pump plant compared to similar systems. The significance of the obtained results lies in the fact that the use of a common storage tank and a combined heat exchanger (AHM generator / HPU heater) provides a significant increase in the coefficient of performance, a decrease in the metal consumption (reduction in costs) of the main equipment.

Thermodynamic and Economic Evaluation of a Novel Green Methanol Poly-Generation System

Methanol is considered a sustainable alternative energy source due to its ease of storage and high-octane rating. However, the conventional methanol production process is accompanied by resource consumption and significant greenhouse gas emissions. The electrochemical reaction of electrochemically reacted hydrogen (H2) with captured carbon dioxide (CO2) offers an alternative route to methanol production. This paper presents a new green poly-generation system consisting of a parabolic trough solar collector (PTC) unit, an organic Rankine cycle (ORC) unit, a CO2 capture unit, an alkaline electrolysis unit, a green methanol synthesis and distillation unit, and a double-effect lithium bromide absorption refrigeration (ARC) unit. The system mainly produced 147.4 kmol/h of methanol at 99.9% purity, 283,500 kmol/h of domestic hot water, and a cooling load of 1341 kW. A total 361.34 MW of thermal energy was supplied to the ORC by the PTC. The alkaline electrolysis unit generated 464.2 kmol/h of H2 and 230.6 kmol/h of oxygen (O2) while providing H2 for methanol synthesis. Thermodynamic and economic analysis of the system was carried out. The energy and exergy efficiency of the whole system could reach 76% and 22.8%, respectively. The internal rate of return (IRR) for the system without subsidies was 11.394%. The analysis for the methanol price showed that the system was economically viable when the methanol price exceedsed$363.34/ton. This new proposed poly-generation system offers more options for efficiently green methanol production.

Energy, exergy, energy-saving, economic and environmental analysis of a micro-gas turbine-PV/T combined cooling, heating and power (CCHP) system under different operation strategies: Transient simulation

A micro-gas turbine (MGT) combined cooling, heating and power system coupled with low concentrating photovoltaic/thermal-heat hump (LCPV/T-HP) and absorption chiller is proposed in this study. LCPV/T is used as the heat source of HP to realize mutual promotion. The performance of CCHP system under different operation strategies is dynamically simulated and analyzed by TRNSYS software from energy, exergy, energy-saving, economy and environment. The results demonstrate that both high temperature water source heat pump (HWHP) and low temperature water source heat pump (LWHP) achieved better COP in following electric load (FEL) mode. The average COP of HWHP and LWHP are 22.69% and 4.75% higher than the rated COP, respectively. Annual total cost per unit building area (ATCUBA) and carbon dioxide emissions per unit building area (CDEUBA) are also more advantageous in FEL mode, while primary energy consumption per unit building area (PECUBA), ATCUBA and CDEUBA seems less preferable in following thermal load (FTL) mode. The exergy efficiency and energy efficiency of the system in FEL mode are 19.96% and 41.90% in summer, and 25.13% and 59.36% in winter. Additionally, the equipment with higher exergy loss is mainly LCPV/T, gas-fired boiler, absorption refrigeration unit, MGT and hot water generator under the three operation strategies.

Exergoeconomic appraisement, sensitivity analysis, and multi-objective optimization of a solar-driven generation plant for yielding electricity and cooling load

Solar energy-driven generation units can assist in moderating energy-linked environmental issues. For this target, a new solar heliostat-based generation unit is suggested for electricity generation as the crucial product. A heliostat-based solar unit with a closed Brayton cycle and thermal energy storage unit is coupled with a Kalina cycle and an absorption refrigeration unit through a single-effect absorption chiller as an inimitable series of power plants. Exergy, economic, and energy investigations are carried out to scrutinize the efficiency of the introduced unit, and a thorough parametric evaluation is performed. Multi-aspect optimization is implemented to identify the optimum decision values, regarding four various scenarios, namely exergy performance/ sum unit cost of the product, exergy performance/ coefficient of performance, NPV/exergy performance, and exergy performance/ cooling load. In this regard, The Grey Wolf Optimizer is the multi-objective optimization method, and TOPSIS, LINMAP, and Shannon entropy approaches assist the optimization procedure in acquiring the optimal solution in each scenario. The results indicate that the optimized exergy performance, coefficient of performance, and sum unit cost of the product are computed as 33.48 %, 0.817, and 3.44 $/GJ, respectively.

A geothermal-biomass powered multi-generation plant with freshwater and hydrogen generation options: Thermo-economic-environmental appraisals and multi-criteria optimization

In the current article, a novel geothermal-biomass-powered multi-generation plant was introduced and probed through thermo-economic-environmental aspects plus multi-criteria optimization. To produce various outcomes, like electricity, heating, cooling, as well as hydrogen and freshwater, the plant took advantage of the Rankine cycle, a dual-effect absorption refrigeration unit, a proton exchange membrane water electrolyzer, and a biomass combustor. The plant's environmental consequences were reviewed based on NOx and CO2 emitting to mark the environmental advantages of burning municipal solid waste as biomass rather than coal. Owing to the investigation, the plant provided 31.68 MW direct power, 39.85 MW heating, 126.36 MW cooling, 23.3 m3/h freshwaters, and 88.12 kg/h hydrogen, besides 58.54% and 16.45% calculated as plant energetic and exergetic efficiencies. By applying the SPECO approach, the total product cost rate was attained at 1.629 $/s. As well, this plant had an exergo-environmental impact factor of 0.9. Moreover, a parametric study was brought out to comprehend the consequences of chief parameter changes. Eventually, a multi-criteria optimization was employed for the plant for the enhancement of the techno-economic operations. In the optimum status, the total cost rate of the product and exergetic efficiency of 1.57 $/s and 17.26% were attainable.

4E assessment and 3D parametric analysis of an innovative liquefied natural gas production process assisted by a diffusion–absorption refrigeration unit

4E assessment and 3D parametric analysis of an innovative liquefied natural gas production process assisted by a diffusion–absorption refrigeration unit

An innovative hybrid system for the polygeneration of power, heat, and liquid carbon dioxide using solid oxide fuel cell/electrolyzer technology and oxyfuel power generation cycle

An innovative polygeneration structure is proposed based on the oxyfuel power generation (OPG) system integration with carbon dioxide (CO2) capture, CO2 power system, NH3/H2O absorption refrigeration (AR) unit, and organic Rankine power (ORP) cycle. In this regard, a combination of solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) is applied to produce the required pure oxygen for the OPG system. The proposed system simultaneously produces 7204 kmol/h hot water, 149.3 kmol/h liquid CO2, and 102.4 MW power in different cycles. Energy and exergy analyses are performed to evaluate the proposed system. The thermodynamic modeling and simulation of power and refrigeration cycles are performed in Aspen HYSYS software, and verified with high accuracy. Also, an integrated SOEC/SOFC simulation has been done using developed computer code in MATLAB programming. The overall electrical efficiency and the AR coefficient of performance are calculated at 31.55% and 0.4803, respectively. In addition, the thermal and exergy efficiencies of the proposed system are 65.10% and 70.60%, respectively. The exergy analysis indicates the combustion chamber's highest exergy destruction with a share of 35.26%. In the next rank, the heat exchangers (26.42%) and turbines (16.98%) have the largest share of degraded exergy among other devices. The sensitivity analysis demonstrates that when the oxygen productivity increases from 9050 to 9275 kg/h, the electrical efficiency in the total integrated structure and the liquid CO2 productivity rise to 34.57% and 6480 kg/h, respectively. Also, by increasing the natural gas entering the proposed structure from 2375 to 2550 kg/h, the exergy efficiency of the structure increases to 71.19% and its thermal efficiency decreases to 58.70%. Highlights A novel polygeneration system to produce power, liquid CO2, and heat is introduced. Integration of oxyfuel/ORC/CO2 power plants and absorption cooling unit is applied. A solid oxide fuel cell/electrolyzer technology is used to produce pure oxygen. The electrical and exergy efficiencies of the overall system are 31.55% and 70.60%. The exergy analysis indicates the combustion chamber has the highest exergy destruction.

Design and Application of Lithium Bromide Absorption Refrigeration Unit in RTO Flue Gas Recovery in Printing Industry

Design and Application of Lithium Bromide Absorption Refrigeration Unit in RTO Flue Gas Recovery in Printing Industry

An idea to efficiently recover the waste heat of Data Centers by constructing an integrated system with carbon dioxide heat pump, mechanical subcooling cycle and lithium bromide-water absorption refrigeration cycle

As a perennial stable heat source, Data Centers release a continuous increasing amount of waste heat. Besides rejecting it into atmosphere by traditional refrigeration ways, how to effectively utilize the waste heat is still an open question. Thus, an idea is proposed to integrate carbon dioxide heat pump with mechanical subcooling cycle and lithium bromide-water absorption refrigeration cycle for the waste heat recovery of Data Centers. The carbon dioxide heat pump is firstly used for upgrading the low-temperature heat of Data Centers, and then the hot water from heat pump is employed to supply heat in winter, drive lithium bromide-water absorption refrigeration cycle in summer for surrounding office buildings. The main function of mechanical subcooling cycle is to increase the cooling capacity of carbon dioxide heat pump, and decrease the required mass flow of carbon dioxide in the Data Centers cooling. For this integrated system, energy, exergy and economic models are respectively established with the help of MATLAB and REFPROP 10 to obtain the corresponding performance. Eight high-temperature mixtures, namely R600a/R601a, R600a/R134a, R600a/R1234yf, R600a/R152a, R600a/R1233zd, R600a /R1234ze and R600a/R236ea, are considered in the mechanical subcooling cycle. The obtained results indicate that the optimum mixture is R600a/R601a (0.4/0.6) with the highest coefficient of performance 2.12 under the discussed conditions, but R600a/R134a (0.5/0.5) with coefficient of performance 2.01 is more recommended out of security. On this basis, exergy destruction and economic analysis are conducted for the use of R134a, R600a and R600a/R134a (0.5/0.5) in mechanical subcooling cycle. Compared with pure fluids R600a and R134a, the exergy destruction of mixture R600a/R134a (0.5/0.5) could be reduced by 593.1 kW ∼ 1114 kW. Besides, the required heat exchanging area of condenser could be diminished by 19.20%∼23.16%. As for the economy, the cost of lithium bromide-water absorption refrigeration unit takes up over the half of the integrated system cost. For different working fluids in mechanical subcooling cycle, the payback period of developed system ranges from 2.04 to 2.46 years.

Experimental study on absorption characteristics of a falling film absorber with micro-scale NH3/LiNO3 liquid film

This work proposed a non-adiabatic absorber with micro-scale falling film with the working pair of ammonia/lithium nitrate. The manufacturing and structure features of the novel absorber has been presented, as well as the experimental facilities of complete absorption refrigeration system. Evaluations and characteristics of mass tansfer process of this novel absorber have been analyzed. Relationships between working conditions such as absorption pressure and cooling water temperature and absorption parameters such as absorption rate, mass transfer coefficents have also been revealed and discussed. Results of this novel micro-scale falling film absorber indicated that, it owns a relatively good performance under high-temperature cooling working condition. Regular working parameters such as absorption rates and mass transfer coefficients are much larger than previous studied adiabatic absorber with structured packing. Moreover, correlations of significant dimensionless parameters have also been concluded for the future research of this micro-scale falling film absorber. • Absorption performances of micro-scale NH 3 /LiNO 3 liquid film is proposed. • Factors of enhancements on absorption process have been comprehensively studied. • Correlations of dimensionless parameters have been established for the novel absorber. This study proposed a novel micro-scale falling film absorber with its experimental data on a complete absorption refrigeration system. Micro-scale liquid-distributor has been carefully designed and manufactured by special techniques. An experimental system for absorption refrigeration has been established to test the novel absorber. This unique absorber applies ammonia/lithium nitrate as working pair which is considered to own application potential for small-scale absorption refrigeration units. Experimental analysis has been done under various of working conditions for making contrasts. Relationships between significant working parameters and absorption parameters have been discussed. Under series of working conditions, absorption rates ranging from 1.2 to 2.6 × 10 −3 kg/(m 2 ·s) have been obtained. Approach to equilibrium factor which characterize the perfection of absorption process ranges from 0.5 to 0.98 while absorption ratio ranges from 0.02 to 0.12. With the increase of Reynolds number from 3 to 52, the mass transfer coefficient rises from 12 to 98 × 10 −6 m/s and Sherwood number ranges from about 30 to 60 respectively. According to the analysis, absorption pressure potential and cooling water temperature are two major factors which enhance the absorption intensity. Absorption pressure potential and inlet solution subcooling degree owns nearly linear relationship with parameters such as absorption rate, absorption ratio and approach to equilibrium factor. However, normalized absorption rate and approach to equilibrium factor gain negative correlations with absorption pressure potential and Reynolds number respectively. Effects of inlet solution flowing features on absorption performance are distinguished under different working condition series. In general, solution flowing intensity inside absorber is a positive factor for absorption process. All the experimental results reveal that, this micro-scale falling film absorber has its priority on absorption perfection and absorption rate for per unit of mass transfer area. Compact structure makes it more valuable for further research and application on small-scale absorption refrigeration unit with the working pair of ammonia/lithium nitrate.

ALGORITHMIC SUPPORT FOR DECISION-MAKING ON THE EFFICIENCY OF OPERATION OF ABSORPTION AND REFRIGERATION PLANTS OF AMMONIA PRODUCTION

The features of the hardware and technological design of the AM-1360 series ammonia synthesis units operating in Ukraine are established, the main of which is the use of heat-using ammonia-water absorption and refrigeration units in the secondary condensation complex. The analysis of the functioning of the absorption and refrigeration units has been carried out. A significant dependence of their efficiency on external disturbances, such as temperature and humidity of atmospheric air, has been established. This causes significant fluctuations in the cooling temperature of the circulating gas in the evaporators of absorption-refrigeration units, which significantly affects the efficiency of ammonia production in general. Based on the results of the analysis of the existing information system, implemented on the basis of the TDC-3000 microprocessor complex, recommendations for its improvement were developed, the presence of which makes it possible to abandon daily analyzes and carry out only control ones to check measuring instruments.
 Algorithmic support has been developed, implemented in the MATLAB package and tested according to the data of industrial operation of absorption and refrigeration units of the ammonia synthesis unit. This allows the operator, in real production conditions, to obtain operational information on the numerical indicators of the efficiency of operation of absorption and refrigeration units, which characterize their operation to the greatest extent (circulation rate, cooling capacity, circulating gas cooling temperature and thermal coefficient) and make a decision on the possibility of reducing the cooling temperature. of circulation gas in evaporators by changing the frequency of circulation of solutions The created algorithmic software in the MATLAB environment allows embedding a client module, the so-called OPC client. The latter provides technology for free programming of access to current data.

Economic and Environmental Analyses of Multi-Generation Renewable Energy System for Dairy Farms

In the present work, economic and environment analyses of multi-generational micro gas turbine systems are reported for a grid-independent dairy farm in Ontario, Canada. Onsite anaerobic digesters utilize farm waste to produce carbon neutral biogas for combustion in the micro gas turbine modules. A range of micro gas turbines coupled with absorption refrigeration units and an organic Rankine cycle are driven by the recovered waste heat to meet the cooling and electrical needs of farm sizes between 250 and 6000 cows. Farms of these sizes are observed to be capable of having their cooling and electricity needs met with micro gas turbines ranging in capacity from 100 to 1000 kW output. Environmental performance is maximized when the net output of the system just matches the energy requirement of the farm, and produces no excess electricity. Thus to minimize the environmental impact, but remain financially viable, various configurations are suggested for farm sizes under 2000 cows.