Optimizing Nh3-H2o Absorption System To Produce Water From Ambient Air

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1 Applied Science Reports E-ISSN: / P-ISSN: DOI: /PSCP.ASR App. Sci. Report. 10 (2), 2015: PSCIPublications Optimizing Nh3-H2o Absorption System To Produce Water From Ambient Air O Titlov, YU Baidak, M Khmelnyuk Odessa national academy of food technologies, 1/3, Dvoryanskaya str., 65082, Odessa, Ukraine Corresponding author titlow@mail.ru Paper Information Received: 11 February, 2015 Accepted: 24 April, 2015 Published: 20 May, 2015 Citation A B S T R A C T The prospects of heat-refrigeration machines application in the systems of producing water from the ambient air are shown in the paper. Powerefficient (for maximum numerical value of heat coefficient) operation regimes of absorption water-ammonia refrigeration machine with regenerative heat exchanger of solutions depending on the ambient air temperature, cooling object temperature, heating source temperature have been defined. The results are presented as analytical and graphical dependencies. Titlov O, Baidak YU, Khmelnyuk M Optimizing Nh3-H2o Absorption System To Produce Water From Ambient Air. Applied Science Reports, 10 (2), Retrieved from (DOI: /PSCP.ASR ) 2015 PSCI Publisher All rights reserved. Key words: water-ammonia absorption refrigeration machine, power efficiency, heat coefficient, operating conditions effect Introduction It is generally known that nowadays water has become the most valuable resource on the planet, and fight for water resources in the modern world is one of the prevailing factors in the armed conflicts, so this tendency will only grow in the visible future. Searching the possible ways of solving this problem, on 5 December 2014, at its 69 th session, the UN General Assembly (GA) approved a resolution on the International Decade for Action Water for Life About 70 percent of the surface of the globe is covered by water, but by 97.5 percent it consists of salt water. The remaining 2.5 percent is freshwater, almost two-thirds of that is frozen in ice caps. Meanwhile, most of the fresh water is in the 1 km layer of the atmosphere. Its overall volume is not less liters. According to Alekseev and Chekarev (1996) the mean absolute humidity near the Earth's surface is 11 g/m 3 and in the tropical regions it reaches 25 g/m 3 or even higher. A large number of tropical countries suffer from a lack of fresh water, although its content in the atmosphere is sufficient. For example, in Djibouti throughout the year there is virtually no rain, but the absolute humidity is g/m 3. The amount of water rushing over every square in 10 km 2 of the Arabian Desert or the Sahara is equal to the lake area of 1 km 2 with a depth of 50 m. Therefore, one of the most important tasks is the development of technology allowing extracting water from the air on the location where it is needed. Since ancient times, the fresh water in very limited quantities was obtained by collecting the condensed droplets from the air as a result of natural daily radiation cooling of the earth surface (porous stones cooling with dew formation at night). For example, in Nouakchott (Mauritania), the average monthly temperature in May and October is C, relative humidity is 60-80%. This means that every cubic meter of air has 20-24g of water. When the temperature is lowered on C, 10-14g of water can be isolated from each cubic meter. In Israel, for example, nights are characterized by favorable conditions for obtaining fresh water from atmospheric air (in Ashdod, Tel Aviv, humidity is usually 100 % in summer time). To increase the efficiency of water vapor condensation process in these conditions the intensifying elements accumulators of cold (gravel), heat pipes, providing heat transfer over long distances or system of sorbent, working in the "charge-discharge" cycle mode are utilized (Perelshtein, 2008). The greatest prospects have methods associated with the operation of independent generators of artificial cold refrigerating machines that are guaranteed to provide a temperature below the dew point temperature. It is known that for obtaining 1 liter of water it is required to spend about 1 kw h of electricity, and at the average from the air flow of 1kg s it is possible to allocate approximately 10g s of water. If refrigerating efficiency of compression refrigerating machine is equal to 3, for producing of 1 liter of water will be consumed approximately 0.33 kw h of energy.

2 Currently, the main volume of the equipment market for water separation from the air falls on the systems, having in its composition compression refrigeration machine with an electric drive. However, the utilization of compression machines is promising only for the performance up to 3-4 liters per hour. At higher performance there is a significant increase in the installation dimensions. A necessary condition for operation of the compression refrigeration machine is the presence of electricity. At the same time, the overwhelming number of countries affected by water scarcity is limited in energy resources. Almost the only available source of energy they have is the sun. Thus, the problem of obtaining water from the atmospheric air is the actual scientific and practical task, which has not been solved yet, and most of the technical proposals remain at the level of patents. Therefore, as the most promising direction we choose utilization of the upgraded absorption refrigerating machines (ARM), working from the low potential heat source solar energy. One of the most promising trend is the ability to use the existing infrastructure of solar water heaters, the total volume of collector area of which in the world is more than 110 million m 2. Analysis of ARM operation mode characteristics showed that the main problems that must be solved when they are used in the systems producing water are as follows: firstly, developing of ARM construction with air cooling of heat dissipating elements, and secondly, to offer a loop which can be implemented in tropical ambient temperatures and temperatures level of traditional water solar collectors ( C). In such circumstances, the greatest prospects have water-ammonia absorption refrigerating machines, which allow designating necessary modification of the cycle. In connection with the choice of water-ammonia absorption refrigerating machines it should be noted that in recent years due to the adverse technogenic impact of refrigeration machines on the environment, more and more attention is paid to the natural refrigerants. Ishchenko et al., (2010) pointed out that recent EU standards clearly regulate the use of specific natural refrigerants for different types of refrigerating machines: for domestic and commercial refrigerators propane; for medium-sized refrigerators carbon dioxide; for larger systems ammonia. Water-ammonia absorption refrigerating machines unlike analogues lithium bromide absorption and vapor jet water refrigerating machines, wherein the refrigerant is water, have a wider field of application, in particular, at negative temperatures down to minus 50 C. For their operation, a variety of heat sources, such as process vapor, hot water, furnace exhaust gases, the exhaust gases of internal combustion engines can be used. Besides tasks of air-conditioning, waterammonia absorption refrigerating machines can also be used in refrigerators during prolonged storage of frozen foods and agricultural products. Water-ammonia absorption refrigerating machines operating on renewable energy sources, in particular, on the solar radiation energy are also of particular interest. This interest comes from the solar collectors year-round utilization possibility, which are currently widely used for heating and hot water. Berchowitz (1996) had assumed that the part of the excess solar energy during the warm period can be sent to the water-ammonia absorption refrigerating machine generator to produce artificial cold. The obtained cold can be used in air-conditioning and refrigerators. Thermodynamic Analysis Of Water-Ammonia Absorption Refrigerating Machines Developing of the algorithm for calculation of pump type water-ammonia absorption refrigerating machine cycles Cycles of water-ammonia absorption refrigerating machines may be completed in the pump and pumpless diagrams. Pumping diagrams have higher power efficiency, but are incorporated with a circulating pump and are not autonomous. Pumpless diagrams are autonomous, but not effective enough. In this paper, we will consider the pumping diagram of water-ammonia absorption refrigerating machine. One feature of water-ammonia absorption refrigerating machine is the temperature interdependence in the cycle typical processes of the heating medium temperature t h, of the cooling medium temperature t W, of the cooling object temperature t ob. Only two of the three temperatures can be set arbitrarily (Sathyabhama, Ashok Babu, 2008; Galimova, 1997). As practice shows, the work of the refrigeration unit should provide a given level of cooling ( t ob C), and the unit itself should operate in the appropriate climatic conditions, i.e. at a given temperature of the cooling medium. Therefore, the actual parameter that can be changed is only the temperature of the heating source. Modern methods of calculation do not take into account such interdependence of temperatures in the absorption refrigeration cycle, because they allow presence of the thermal energy source with the required temperature potential (Ishchenko, 2010; Sathyabhama A., Ashok Babu T.P, 2008; Galimova, 2007). At the same time, analysis of the non-utilized and alternative thermal energy sources parameters shows that much of it can not be used to implement traditional cycles of water-ammonia absorption refrigerating machines due to insufficient high temperature potential. These sources include exhaust gases, geothermal and solar collectors. To work with low-potential sources of heat energy an algorithm for calculation of pump type water-ammonia absorption refrigerating machines cycles has been developed. Figure 1 shows a diagram of the pumping water-ammonia absorption refrigerating machine with two liquid suction heat interchangers (superheaters) of liquors and ammonia. To generator 1, which is filled with water-ammonia 91

3 liquor, low-potential heat is supplied, and a low-boiling component (ammonia) with minor particles of water vapor will preferably boil away from the liquor. Vapor enters the rectifier 2, wherein the water-ammonia liquor from the superheater of liquors 5 and absorber 4 it flows toward the vapor flow that comes from the generator 1. In this case, the less volatile water vapors condense first, at the same time increasing ammonia concentration in the flow. Then the vapors of waterammonia liquor get to rectifier 3. On its cold pipes, water vapors that remained after the analyser 2 condensed first. The presence of the analyser 2 and rectifier 3 in the scheme of water-ammonia absorption refrigerating machine allows to get rid of the water vapor in the ammonia vapor flow, which goes to the condenser 7. Further ammonia vapor enters condenser 7, liquefies with phase transition heat removing, enters the superheater of ammonia 8 wherein the cold ammonia vapor that comes from the evaporator 9 into the absorber 4 is preheated, thereby increasing the thermal efficiency of water-ammonia absorption refrigerating machine cycle. Figure 1. Diagram of the pumping water-ammonia absorption refrigerating machine with two liquid suction heat interchangers (superheaters): 1 generator; 2 analyser; 3 rectifier; 4 absorber; 5 superheater of liquor; 6 pump; 7 condenser; 8 superheater of ammonia; 9 evaporator; 10 cock-1, 11 cock-2. Liquid ammonia is throttled in the cock-1 and boils in the evaporator 9, at the same time developing artificial cold. Ammonia vapor is supplied from the evaporator 9 through superheater of ammonia 8 to the absorber 4, where it is absorbed and dissolved in the weak (with minimal ammonia composition) water-ammonia liquor, which comes from the generator 1 through the superheater of liquor 5, in which with the help of weak water-ammonia liquor heat the strong liquor which enters the generator 1is heated. Further saturated water-ammonia liquor is throttled in the cock-2 and enters the absorber 4. From absorber 4 by the pump 6 strong water-ammonia liquor flows into water-ammonia liquor analyser 2 and the cycle is repeated. Initial data for calculation are as follows: a) cooling medium temperature t W ; b) cooled object temperature t ob ; c) temperature differences on the elements that are not explicitly take into account the conditions of heat transfer and partial heat recovery: t h temperature difference between weak water-ammonia liquor and heating generator heat source; t WK, twa, trec temperature head in the condenser, absorber, rectifier with a cooling medium; t ТО temperature head between the flows of weak and strong water-ammonia liquor at the cold end of superheater of liquor; d) refrigerating capacity of the evaporator Q 0. 92

4 Variable parameter is the temperature of the heating source of heat t h. Stages of research On the first phase of research using the given above algorithm the search of heating source temperature ranges ( t h ), which would satisfy the water-ammonia absorption refrigerating machine operation conditions ( t W ) and t requirements to the cooled object ( ob ) was performed. The relevance of this study was associated with the fact that some water-ammonia absorption refrigerating machine operation modes can not be held due to insufficiently high temperature of heating source. For example, the cooling temperature level requires corresponding pressure level Po in the absorber. The equilibrium temperature of strong water-ammonia liquor in the absorber t кр. А should be higher than the temperature of the cooling medium in order to provide the removal of absorption heat. Mass fraction of ammonia in a strong water-ammonia liquor st. is determined by the values P o and t кр. А, and for the organization of the absorption process it is necessary some degassing zone the difference between the mass fraction of ammonia in strong st. and weak weak. water-ammonia liquor. In turn, the mass fraction of ammonia in the weak water-ammonia liquor weak. is determined by the values of the condensing-generation pressure P k and the temperature of the heating source t h. Search algorithm of water-ammonia absorption refrigerating machine operating modes was as follows. On the first stage the temperatures of the cooling object t o -30 C; minus 15 C; -5 C were set. For each value of tob calculations with a fixed value t W with a range of C in increments of 1 C were carried out. For given values tob and t W calculations of circulation ratio with variable t h in increments of 1 C was performed. If the multiplicity of circulation is a positive quantity, it was concluded that the water-ammonia absorption refrigerating machine operation mode could be implemented, and otherwise, when the value of the multiplicity of circulation was negative it was concluded that the mode of operation did not exist. The calculations results for the given algorithm presented in Figure 2. The obtained dependences are the minimum required values of heating medium temperatures for the operation conditions of real water-ammonia absorption refrigerating machine. Analysis of these results indicates that water-ammonia absorption refrigerating machine in a system with solar collector working on water as a coolant can be used only in air conditioning systems at a temperature of the cooling medium no higher than C. To work in cooling systems with temperatures down to minus 30 C, a temperature of the heating medium C is necessary. Figure 2. The results of the calculation of the minimum temperature of the heating source ( t h ) depending on the cooling temperature of the object ( t ob )and the cooling medium ( t W ) 93

5 η Figure 3. The results of calculation of the power characteristics: of the cycle heat coefficient (η) and power of the circulating pump ( L pump ) of pumping water-ammonia absorption refrigerating machine at various ambient temperatures ( t W ) and the heating medium ( t h ), at a cooled object temperature ( t ob ): a),b) t ob = -5 C; c), d) t ob = -15 C e), f) t ob = -25 C 94

6 Dependence has the form: On the second stage analysis of pumping water-ammonia absorption refrigerating machine cycles was carried out and cycles power characteristics heat coefficient and circulation pump operation, depending on the temperature of the heating source were determined. Cooling object temperature in the calculations was as follows: -5 C; - 15 C; - 25 C, cooling medium temperature: from 10 to 32 C. Temperature heads on the elements have been taken equal to 5 C, and the generator to 10 C. Minimum temperature of the heating medium in the analysis was 90 C, maximum 170 C. The value for the minimum temperature was chosen on the boundary of water-ammonia absorption refrigerating machine cycles realization, and the maximum in view of structural material active corrosion beginning. The results of calculation of water-ammonia absorption refrigerating machine pumping diagram is presented in the form of plots in Figure. 3. One of the key moments in the development of new power equipment is power efficiency of units. Analytical calculations for searching the power-saving operation modes of water-ammonia absorption refrigerating machine (on the maximum of heat coefficient of the refrigeration cycle that used heat) in a wide range of parameters have been carried out due to the fact that all three temperature sources(of heating medium, cooled object, cold source) affect on the power characteristics of water-ammonia absorption refrigerating machine. An analytical study of water-ammonia absorption refrigerating machine with superheater cycle has been performed and dependencies of the heating source temperature at different temperatures of the cooled object and cooling medium, which ensured maximum power efficiency under these conditions have been built (Figure 4). Analytical dependency between the cooling medium temperature ( t W ), temperature of the cooled object ( t ob ), and the heating source temperature ( t h ) provided with a maximum value of heat coefficient was defined and built. The maximum error of the analytical dependence is 5.3%. The average error is 1.1% Surface type, which analytical dependence describes is shown in Figure 4. Analysis of the results of calculation leads to the following conclusions. Firstly, in the range of design parameters occurs maximum power efficiency of water-ammonia absorption refrigerating machine. Most clearly is the presence of the maximum for the operation conditions at temperatures of cooling medium C and low temperatures of cooled object (-25 C). By reducing the temperature of the cooled object maximum power efficiency is shifted to the area of high temperatures of heating medium and its numerical values decrease. For example, at a temperature of the cooling medium 26 C and the temperature of the cooled object minus 5 C the maximum of cycle heat coefficient takes place at a temperature of cooled object 110 C, at minus 15 C at 120 C, at minus 25 C at 140 C, so correspondingly values of heat coefficient are: 0.53; 0.44; Analysis of calculation results showed that such a movement of dependencies is due to: a) in low-temperatures area of heating medium (up to a maximum heat coefficient) high magnification of waterammonia liquor circulation between the generator and the absorber (from 6 to 112), which is due to the narrow area of degassing ; b) in high temperature area of the heating medium (after the maximum of heat coefficient) increase of the water proportion in the water-ammonia mixture vapor flow exiting from the generator for example, at a temperature of the cooling medium 26 C and the temperature of cooled object minus 5 C, the increase of water vapor proportion in the mixture is from till 0.408, i.e. more than 10 times. In the first case, there are additional heat flows to generator with a strong flow of strong water-ammonia liquor. 95

7 Figure 4. The dependence between the temperatures of the heating source ( t h ), of the cooled object ( t ob ) and the environment ( t W ) with a maximum numerical value of water-ammonia absorption refrigerating machine cycle heat coefficient In the second case, despite a decrease in circulation ratio of water-ammonia liquor, thermal load in the generator increases due to additional costs for the evaporation of water-absorbent. Growth of rectifier heat load correspondingly also increases more than 10 times (at a temperature of cooling medium 26 C and the cooled object temperature minus 5 C from kj/kg to 2,200 kj/kg). Reducing of the water-ammonia absorption refrigerating machine cycle heat coefficient while reducing the cooling temperatures level is explained with a fact that for the low-temperature cycle realization it is required waterammonia absorption refrigerating machine with a high proportion of absorbent in the absorber, and this is connected with additional evaporation of water in the generator. For example, at a temperature of cooling medium 26 C, temperature reduction of the cooled object from minus 5 C to minus 25 C requires a reduction in the proportion of ammonia in the weak water-ammonia liquor from to At the same time, despite a decrease in the heat load of the generator because of reduced circulation ratio of water-ammonia liquor, advancing adverse impact has the process of additional evaporation of water vapor. In the estimated range in all cases an increase of the heating source temperature leads to a sharp decrease in the power of the circulating pump pumping strong liquor from the absorber to the generator. The calculations showed that at temperatures of the heating source from 90 C to 130 C (depending on the cooling medium temperature) the capacity of the circulation pump has maximum value. Then, with increasing of the heating source temperature its asymptotic reduction and slow decrease is observed. The biggest changes in this case occur at elevated temperatures of the cooling medium (32 C). Taking into account the above analysis of various types of refrigeration machines of absorption type and the results of the analysis of power characteristics of water-ammonia absorption refrigerating machine cycles, as well as the simplicity of design and implementation of a method for further development the variant of traditional water-ammonia absorption refrigerating machine with superheater of liquor and a booster compressor on the line to supply ammonia vapor to the condenser was selected (Figure 5). 96

8 Figure 5. Diagram of water-ammonia absorption refrigerating machine with a biasing booster compressor before condenser: 1 generator-boiler; 2 air condenser; 3 throttle of liquid ammonia; 4 air cooler; 5 absorber; 6 weak liquor air cooler; 7 pump of strong liquor; 8 throttle of weak liquor; 9 superheater of liquor; 10 booster compressor Operation of water-ammonia absorption refrigerating machine with booster compressor Operation of water-ammonia absorption refrigerating machine with booster compressor is as follows. Into the vapor generator 1, the heat load is applied. As the coolant we consider water as the most widespread case. The heated water is circulated through the heat exchanged inner tubes of generator 2, transfers the heat to the strong water-ammonia liquor. From the water-ammonia liquor at a pressure Р г the low-boiling component ammonia with some parts of absorbent water predominantly evaporates. Depleted in ammonia water-ammonia liquor weak waterammonia liquor, having a higher density is moved into the lower part of the generator 1, and the water-ammonia vapor mixture rises into the upper part of the generator 1. In the upper part of the vapor generator takes place the cleaning of vapor mixture due to the difference of the normal boiling temperatures of the water and ammonia by distillation and reflux. Purified ammonia vapor is input to the booster compressor 10, compressed and with the increased, in comparison with the pressure in the generator (Р г ), pressure Р к, is supplied to the air condenser 2. In the condenser 2 vapor liquefies with the removing of vaporization heat to the ambient air. Liquid ammonia after condenser 2 is passing through the throttle 3 loses pressure Р к till Р о and in the form of wet vapor (liquid and vapor mixture) enters the air cooler 4. In the air cooler liquid ammonia boils at a lower pressure Р о and temperature Т о with heat from the outside air removal. The constant pressure in the evaporator Р о is maintained by removing ammonia vapor into the absorber 5 where it is absorbed by the weak water-ammonia liquor supplied from the generator 1 via a throttle 8. From absorber 5 ammoniated strong waterammonia liquor using circulation pump 7 overcomes the pressure differential ΔР = Р г - Р о and flows into the generator 1 and the water-ammonia absorption refrigerating machine cycle is repeated. For power-efficient operation of waterammonia absorption refrigerating machine superheater of liquor 9 is set in the circuit, wherein the heated in generator 1 weak water-ammonia liquor changed with heat with a strong water-ammonia liquor coming from the absorber 5. To improve the efficiency of the absorber operation in the circuit there is a special weak liquor air cooler 6 in front of the absorber 5. Air cooling of heat dissipating elements is provided in the scheme, as the operation of water-ammonia absorption refrigerating machine is planned in the conditions of the water resources shortage. With an original algorithm for calculating of water-ammonia absorption refrigerating machine the analysis of water-ammonia absorption refrigerating machine with a biasing booster compressor before condenser cycles was also performed. The results of the calculations are shown in Figure 6 - effect of temperature on the heating source on the MCOP of cycle of water-ammonia absorption refrigerating machine cycle with a biasing booster compressor before condenser (cooled object temperature 0 C, the outside temperature 32 C) and Figure 7 -. Influence of ambient air temperature on MCOP of cycle of water-ammonia absorption refrigerating machine cycle with a biasing booster compressor before condenser and on the coefficient of performance (COP) of the ideal Carnot cycle of vapor-compression refrigerating machine:1, 3 - cycle of water-ammonia absorption refrigerating machine cycle with a biasing booster compressor before condenser ; 2 - vapor-compression refrigerating machine cycle;the temperature of the heating source of water-ammonia absorption refrigerating machine: 1 90 C; C. 97

9 The "modified coefficient of performance" (MCOP) of the water-ammonia absorption refrigerating machine cycle (η), which is the ratio of useful effect (artificial cold) with expended in the circulation pump 7 and booster compressor electric power is of great interest. Given the fact that the heat energy of the heating source comes from the solar collector, as a gift, we have not considered it. Analysis of Figure 6 shows that with the increase in temperature of the heating source from 80 C to 100 C the efficiency of water-ammonia absorption refrigerating machine is doubled. We have also compared water-ammonia absorption refrigerating machine with a biasing booster compressor before condenser cycle that works at the same range of parameters of cooled object and outdoor air temperatures. The results of the comparison of vapor-compression refrigerating machine cycle working on the ideal Carnot cycle and water-ammonia absorption refrigerating machine cycle with a biasing booster compressor before condenser are shown in Figure 7. Analysis of the plots shows that water-ammonia absorption refrigerating machine cycle with a biasing booster compressor before condenser have some power advantages even before the ideal Carnot refrigeration cycle, starting from the temperature level of the heating source 100 C. Power advantage in the considered range of temperature settings is ranging from 11 to 24%. Conclusions And Discussion An original search algorithm of the minimum required temperature of the heating medium, depending on the temperature of the cooled object and the cooling medium for the real water-ammonia absorption refrigerating machine. When implementing the traditional cycles of water-ammonia absorption refrigerating machine takes place the modes with a maximum power efficiency in the practical temperature range of the cooling medium (from 10 to 32 C) and cooled objects (from minus 25 to minus 5 C). To achieve these optimal modes an appropriate combination of strong waterammonia liquor and temperature of the heating source. Operation of pumping scheme of water-ammonia absorption refrigerating machine in the area of lowtemperatures heating source (from 90 to 120 C) presupposes the existence of a circulation pump with installation capacity of 2-3 orders higher than the capacity of the pump operating in the circuit in the temperature range of the heating source from 120 to 160 C. According to the results of calculations and analysis is was proposed the scheme of waterammonia absorption refrigerating machine cycle with a biasing booster compressor before condenser for operation in systems for receiving water from the atmosphere air with heat source from the solar collector with water heat transfer agent. These schemes, despite the extra energy expenses to drive the compressor, can provide water-ammonia absorption refrigerating machine operation with a heat source having temperature from 80 C, with an increase in temperature of the heating source from 80 C to 100 C power efficiency of water-ammonia absorption refrigerating machine is doubled. Analysis of the power characteristics shows that water-ammonia absorption refrigerating machine cycle with a biasing booster compressor before condenser have some power advantages even before the ideal Carnot refrigeration cycle, starting from the temperature level of the heating source 100 C. Power advantage in the considered range of temperature settings is ranging from 11 to 24%. Nomenclature t heating medium temperature; h t cooling medium temperature; W Figure 6 Figure 7 98

10 t ob cooling object temperature; t h temperature difference between weak water-ammonia liquor and heating generator heat source; t WK, twa, trec temperature head in the condenser, absorber, rectifier with a cooling medium; t ТО temperature head between the flows of weak and strong water-ammonia liquor at the cold end of superheater of liquor; Q 0 refrigerating capacity of the evaporator; t h temperature of the heating source of heat; t кр. А equilibrium temperature of strong water-ammonia liquor in the absorber; η cycle heat coefficient; L power of the circulating pump pump References Alekseev V, Chekarev K Obtaining fresh water from moist air, Arid ecosystems, 2 3: Berchowitz DM Stirling coolers for solar refrigerators, Presented at the International Appliance Technical Conference, May 13-15, 1996, Purdue University, West Lafayett, IN. Reproduced with permission Ischenko I Development of systems for receiving water from air-based heat-chillers, Modern problems of refrigeration engineering and technology, 4: Ischenko I Simulation of pumping cycles and pumpless absorption refrigeration units, Proceedings of Odessa National Academy of Food Technologies, 38(2): Perelshteyn V New Energy Systems, Kazan 244 p. Sathyabhama A, Ashok Babu TP.2008.Thermodynamic simulation of ammonia-water absorption refrigeration system, Thermal science. Vol.12 (3):45-53 Galimova L., 1997,Absorption refrigerating machine and heat pumps, Astrahan: 226 p. 99