Adsorption Transformation of Heat : The Applicability in Various Climatic Zones of the Russian Federation

Adsorption heat transformation (AHT) is energy and environment saving technology that allows the effective utilization of renewable and waste heat with low-temperature potential. For the enhancement of AHT efficiency, properties of the working pair “adsorbent–adsorbate” have to be intelligently adapted to the operating conditions of the specific AHT cycle. In this work, the applicability of ATH technology in the Russian Federation (RF) was analyzed. For various geographic zones of the RF, the proper AHT application (cooling, heating, heat amplification, or storage) was selected depending on the zone climatic conditions. Data on the adsorption equilibrium for more than 40 “adsorbent–adsorbate” pairs collected from the literature were analyzed to select the most suitable pairs for the particular application/zone. Recommendations on AHT applications and the proper working pairs for the considered RF climatic zones are made.


Introduction
Because of the danger posed by the ever-worsening environmental situation on the planet (global warming, depletion of fossil fuels, etc.), initiatives need to be taken to alleviate the current ambiance.The key to solving this problem is to work out the following scientific and technical goals: (1) the decrease in energy consumption through energy efficiency measures including reducing the share of waste heat (thermal waste from industry, transport, etc.) dissipated to the environment; and (2) the use of alternative energy sources (solar energy, geothermal, waste heat, etc.).These thermal energy sources are characterized by a significantly lower temperature potential than that achieved by burning fossil fuels, which opens up broad prospects for the use of adsorption heat transformation (AHT) systems [1].AHT is an environmentally friendly technology, which allows the utilization of waste or renewable heat and reduction in the consumption of fossil fuels.Contrary to conventional compression heat pumps and chillers, AHT is characterized by low consumption of electricity, production of which is currently dominated by coal and is expected to remain so.Consequently, the broader dissemination of AHT technology will promote the reduction of indirect emissions of greenhouse gases [2,3].Moreover, this technology is non-freon because benign liquids, such as water and alcohols, are used as working fluids.Significant progress has been achieved in AHT over the past decades [4,5].
AHT is based on reversible exothermal adsorption and endothermal desorption processes and can be used for various applications, namely cooling, heating, heat storage and amplification, and their combinations.It is well known that the adsorbent that is optimal for AHT must exchange a large amount of adsorbate under the conditions of the cycle under consideration [6].A high affinity of the adsorbent to the adsorbate is favorable for obtaining a high adsorption capacity.However, such a strong interaction leads to high desorption temperatures (>200-300 • C), as in the case of zeolites.On the other hand, the low affinity of the adsorbent to the adsorbate favors desorption, but it cannot efficiently convert heat during the sorption phase.Temperature lift in this case will be low.Thus, the optimal adsorbent should provide a moderate affinity for the sorbate, which depends on the boundary conditions of the cycle.In other words, the efficiency of the specific AHT cycle depends mainly on the agreement between the operating conditions of the cycle and the adsorption equilibrium of the employed working pair.The operating conditions of an AHT cycle are determined by the boundary temperatures of evaporator, condenser, and external heat source.They, in turn, depend on the climatic conditions of the region in which the AHT cycle is realized, the application (cooling, heating, heat storage, or amplification), and heat source used for the adsorbent regeneration.Therefore, for effective AHT cycle realization, a working pair "adsorbent-adsorbate" should be intelligently selected in accordance with the mentioned boundary conditions of the cycle [6].
There is a fairly large amount of research summarizing data on the adsorption equilibrium of existing working pairs for AHT [7][8][9][10][11].Taking into account the importance of harmonization between the operating conditions of the AHT cycle and the properties of the employed working pair, the performance of an AHT cycle is usually evaluated considering the specific climatic conditions of the region where it is realized [12][13][14].For example, the authors of [15] investigated adsorption cooling for storage of vaccines in the Sahara climate.The work [16] considered the organization of the cycle of sorption cooling in Tokyo's climatic conditions.The authors of [17] discussed sorption cooling and the production of warm water in the conditions of the city Dhaka.Thus, detailed analysis of the applicability of various working pairs for specific AHT applications and climatic conditions will promote the advancement of this energy and environment saving technology.
As the Russian Federation (RF) is one of the top CO 2 emitters, such an analysis performed for the RF is of primary importance.In this work, for the first time, the feasibility analysis of AHT technology under the climatic conditions of the RF is carried out.First, the climatic conditions of selected RF regions are analyzed and the proper AHT applications are defined for each zone.Then, specific requirements to properties of the adsorbent optimal for the selected zones and applications are considered in terms of the Polanyi-Dubinin adsorption potential, corresponding to the adsorption and desorption stages of the analyzed cycle.Finally, the most promising working pairs are selected for the specific application/zone.This selection is based on an analysis of literature data on the adsorption equilibrium of numerous common and innovative adsorbents with water and methanol vapors.These adsorbates are considered as working fluids because of their promise for AHT [6].Water can be utilized for AHT applications at above-zero temperature, e.g., air conditioning and warm water production in the summer time.For seasonal heat storage and amplification of temperature potential, methanol should be used because of its low freezing temperature and high operating vapor pressure.

Methodology of the Analysis
A common AHT cycle consists of two isobars and two isosteres in the Clausius-Clapeyron coordinates ln(P) vs. (−1/T) (Figure 1a).The temperatures of evaporator Tev, condenser Tcon, adsorption Tads, and regeneration Treg completely define this four temperature (4T) cycle.The efficiency of the adsorbent use in a particular AHT cycle is higher if the amount of adsorbate exchanged under the conditions of the cycle is larger [6].To estimate the mass of adsorbate that the adsorbent will exchange in a specific cycle the following route is suggested: (1) measurement of adsorption isobar at the pressure Pev, and determination of the equilibrium adsorbate uptake wmax at the temperature Tads, (2) measurement of the isobar at the pressure Pcon and determination of the equilibrium adsorbate uptake wmin at the temperature Tdes as well as the amount of exchanged adsorbed ∆w = wmax − wmin.This difference has to be maximized.Such measurements are time and labor consuming.On the other hand, for the same working pairs, the adsorption equilibrium data has already been reported in the literature, however, they were measured at temperatures and pressures different from those in the cycle studied.In this case, the equilibrium uptakes can be evaluated from the universal adsorption curve "the adsorption capacity w-the adsorption potential ∆F" plotted on the basis of the already available experimental data.The Polanyi adsorption potential ∆F = −RT ln[P/P o (T)], where P o is the saturated vapor pressure at temperature T, was introduced in 1914, considering the adsorption process similar to the compression of adsorbate vapor in a certain field of adsorption forces near the adsorbent surface [18].Later, it was shown that the adsorption potential ∆F can be used as a universal measure of the adsorbent affinity to the adsorptive [19].It was found in [20] that for many adsorbents, both micro-and mesoporous, there is a one-to-one correspondence between the equilibrium uptake w and the ∆F-value w = f (∆F) (Figure 1b).In other words, adsorption curves measured at different conditions coincide in the coordinates "w vs. ∆F "(Figure 1b).
Appl.Sci.2019, 9, x FOR PEER REVIEW 3 of 13 at the temperature Tads, (2) measurement of the isobar at the pressure Pcon and determination of the equilibrium adsorbate uptake wmin at the temperature Tdes as well as the amount of exchanged adsorbed Δw = wmax − wmin.This difference has to be maximized.Such measurements are time and labor consuming.On the other hand, for the same working pairs, the adsorption equilibrium data has already been reported in the literature, however, they were measured at temperatures and pressures different from those in the cycle studied.In this case, the equilibrium uptakes can be evaluated from the universal adsorption curve "the adsorption capacity w-the adsorption potential ΔF" plotted on the basis of the already available experimental data.The Polanyi adsorption potential ΔF = −RT ln[P/Po(T)], where Po is the saturated vapor pressure at temperature T, was introduced in 1914, considering the adsorption process similar to the compression of adsorbate vapor in a certain field of adsorption forces near the adsorbent surface [18].Later, it was shown that the adsorption potential ΔF can be used as a universal measure of the adsorbent affinity to the adsorptive [19].It was found in [20] that for many adsorbents, both micro-and mesoporous, there is a one-to-one correspondence between the equilibrium uptake w and the ΔF-value w = f(ΔF) (Figure 1b).In other words, adsorption curves measured at different conditions coincide in the coordinates "w vs. ΔF "(Figure 1b).The weak adsorption isostere (line 3-4 on Figure 1a) corresponds to the adsorption potential ΔF1 at the end of desorption stage (point 3) and to the minimal uptake wmin = w (ΔF1).The rich isostere (line 1-2) corresponds to the end of adsorption stage (point 1) and to the maximal uptake wmax = w (ΔF2), where Therefore, the requirements for the adsorbent optimal for the specific AHT cycle can be formulated in terms of the boundary adsorption potentials ΔF1 and ΔF2: the adsorbent should exchange as much adsorbate as possible in the ΔF-interval between ΔF1 and ΔF2.The boundary potentials are defined by the operating temperature Treg, Tcon, Tads, and Tev.These temperatures, in turn, depend on the climate of the place where the AHT unit is used, regeneration temperature, and temperature of the required useful heat/cold.
In adsorption technologies, both traditional (activated carbons, zeolites, silica gels) and innovative materials (aluminophosphates, metal organic frameworks, composites "salt in a porous matrix"-CSPM) are used as sorbents.Pure (AlPO) and substituted aluminophosphates (MeAPO) at the temperature Tads, (2) measurement of the isobar at the pressure Pcon and determination of the equilibrium adsorbate uptake wmin at the temperature Tdes as well as the amount of exchanged adsorbed Δw = wmax − wmin.This difference has to be maximized.Such measurements are time and labor consuming.On the other hand, for the same working pairs, the adsorption equilibrium data has already been reported in the literature, however, they were measured at temperatures and pressures different from those in the cycle studied.In this case, the equilibrium uptakes can be evaluated from the universal adsorption curve "the adsorption capacity w-the adsorption potential ΔF" plotted on the basis of the already available experimental data.The Polanyi adsorption potential ΔF = −RT ln[P/Po(T)], where Po is the saturated vapor pressure at temperature T, was introduced in 1914, considering the adsorption process similar to the compression of adsorbate vapor in a certain field of adsorption forces near the adsorbent surface [18].Later, it was shown that the adsorption potential ΔF can be used as a universal measure of the adsorbent affinity to the adsorptive [19].It was found in [20] that for many adsorbents, both micro-and mesoporous, there is a one-to-one correspondence between the equilibrium uptake w and the ΔF-value w = f(ΔF) (Figure 1b).In other words, adsorption curves measured at different conditions coincide in the coordinates "w vs. ΔF "(Figure 1b).The weak adsorption isostere (line 3-4 on Figure 1a) corresponds to the adsorption potential ΔF1 at the end of desorption stage (point 3) and to the minimal uptake wmin = w (ΔF1).The rich isostere (line 1-2) corresponds to the end of adsorption stage (point 1) and to the maximal uptake wmax = w (ΔF2), where Therefore, the requirements for the adsorbent optimal for the specific AHT cycle can be formulated in terms of the boundary adsorption potentials ΔF1 and ΔF2: the adsorbent should exchange as much adsorbate as possible in the ΔF-interval between ΔF1 and ΔF2.The boundary potentials are defined by the operating temperature Treg, Tcon, Tads, and Tev.These temperatures, in turn, depend on the climate of the place where the AHT unit is used, regeneration temperature, and temperature of the required useful heat/cold.
In adsorption technologies, both traditional (activated carbons, zeolites, silica gels) and innovative materials (aluminophosphates, metal organic frameworks, composites "salt in a porous matrix"-CSPM) are used as sorbents.Pure (AlPO) and substituted aluminophosphates (MeAPO) at the temperature Tads, (2) measurement of the isobar at the pressure Pcon and determination of the equilibrium adsorbate uptake wmin at the temperature Tdes as well as the amount of exchanged adsorbed Δw = wmax − wmin.This difference has to be maximized.Such measurements are time and labor consuming.On the other hand, for the same working pairs, the adsorption equilibrium data has already been reported in the literature, however, they were measured at temperatures and pressures different from those in the cycle studied.In this case, the equilibrium uptakes can be evaluated from the universal adsorption curve "the adsorption capacity w-the adsorption potential ΔF" plotted on the basis of the already available experimental data.The Polanyi adsorption potential ΔF = −RT ln[P/Po(T)], where Po is the saturated vapor pressure at temperature T, was introduced in 1914, considering the adsorption process similar to the compression of adsorbate vapor in a certain field of adsorption forces near the adsorbent surface [18].Later, it was shown that the adsorption potential ΔF can be used as a universal measure of the adsorbent affinity to the adsorptive [19].It was found in [20] that for many adsorbents, both micro-and mesoporous, there is a one-to-one correspondence between the equilibrium uptake w and the ΔF-value w = f(ΔF) (Figure 1b).In other words, adsorption curves measured at different conditions coincide in the coordinates "w vs. ΔF "(Figure 1b).The weak adsorption isostere (line 3-4 on Figure 1a) corresponds to the adsorption potential ΔF1 at the end of desorption stage (point 3) and to the minimal uptake wmin = w (ΔF1).The rich isostere (line 1-2) corresponds to the end of adsorption stage (point 1) and to the maximal uptake wmax = w (ΔF2), where ΔF1 = −RTregln[P(Tcon)/P(Treg)], (1) Therefore, the requirements for the adsorbent optimal for the specific AHT cycle can be formulated in terms of the boundary adsorption potentials ΔF1 and ΔF2: the adsorbent should exchange as much adsorbate as possible in the ΔF-interval between ΔF1 and ΔF2.The boundary potentials are defined by the operating temperature Treg, Tcon, Tads, and Tev.These temperatures, in turn, depend on the climate of the place where the AHT unit is used, regeneration temperature, and temperature of the required useful heat/cold.
In adsorption technologies, both traditional (activated carbons, zeolites, silica gels) and innovative materials (aluminophosphates, metal organic frameworks, composites "salt in a porous matrix"-CSPM) are used as sorbents.Pure (AlPO) and substituted aluminophosphates (MeAPO) at the temperature Tads, (2) measurement of the isobar at the pressure Pcon and determination of the equilibrium adsorbate uptake wmin at the temperature Tdes as well as the amount of exchanged adsorbed Δw = wmax − wmin.This difference has to be maximized.Such measurements are time and labor consuming.On the other hand, for the same working pairs, the adsorption equilibrium data has already been reported in the literature, however, they were measured at temperatures and pressures different from those in the cycle studied.In this case, the equilibrium uptakes can be evaluated from the universal adsorption curve "the adsorption capacity w-the adsorption potential ΔF" plotted on the basis of the already available experimental data.The Polanyi adsorption potential ΔF = −RT ln[P/Po(T)], where Po is the saturated vapor pressure at temperature T, was introduced in 1914, considering the adsorption process similar to the compression of adsorbate vapor in a certain field of adsorption forces near the adsorbent surface [18].Later, it was shown that the adsorption potential ΔF can be used as a universal measure of the adsorbent affinity to the adsorptive [19].It was found in [20] that for many adsorbents, both micro-and mesoporous, there is a one-to-one correspondence between the equilibrium uptake w and the ΔF-value w = f(ΔF) (Figure 1b).In other words, adsorption curves measured at different conditions coincide in the coordinates "w vs. ΔF "(Figure 1b).The weak adsorption isostere (line 3-4 on Figure 1a) corresponds to the adsorption potential ΔF1 at the end of desorption stage (point 3) and to the minimal uptake wmin = w (ΔF1).The rich isostere (line 1-2) corresponds to the end of adsorption stage (point 1) and to the maximal uptake wmax = w (ΔF2), where ΔF1 = −RTregln[P(Tcon)/P(Treg)], (1) Therefore, the requirements for the adsorbent optimal for the specific AHT cycle can be formulated in terms of the boundary adsorption potentials ΔF1 and ΔF2: the adsorbent should exchange as much adsorbate as possible in the ΔF-interval between ΔF1 and ΔF2.The boundary potentials are defined by the operating temperature Treg, Tcon, Tads, and Tev.These temperatures, in turn, depend on the climate of the place where the AHT unit is used, regeneration temperature, and temperature of the required useful heat/cold.
In adsorption technologies, both traditional (activated carbons, zeolites, silica gels) and innovative materials (aluminophosphates, metal organic frameworks, composites "salt in a porous matrix"-CSPM) are used as sorbents.Pure (AlPO) and substituted aluminophosphates (MeAPO) The weak adsorption isostere (line 3-4 on Figure 1a) corresponds to the adsorption potential ∆F 1 at the end of desorption stage (point 3) and to the minimal uptake wmin = w (∆F 1 ).The rich isostere (line 1-2) corresponds to the end of adsorption stage (point 1) and to the maximal uptake wmax = w (∆F 2 ), where ∆F 1 = −RTregln[P(Tcon)/P(Treg)], (1) Therefore, the requirements for the adsorbent optimal for the specific AHT cycle can be formulated in terms of the boundary adsorption potentials ∆F 1 and ∆F 2 : the adsorbent should exchange as much adsorbate as possible in the ∆F-interval between ∆F 1 and ∆F 2 .The boundary potentials are defined by the operating temperature Treg, Tcon, Tads, and Tev.These temperatures, in turn, depend on the climate of the place where the AHT unit is used, regeneration temperature, and temperature of the required useful heat/cold.

Analysis of the AHT Cycles Demanded in the RF and Appropriate Working Pairs
Seven settlements from different climatic zones of the RF are chosen for further detailed analysis (Figure 2), namely, Astrakhan (I zone), Moscow (II zone, western part of the RF), Vladivostok (II zone, eastern part of the RF), Omsk (III zone), Arkhangelsk (IV zone, northern part of the RF), Yakutsk (IV zone, eastern part of the RF), and Oymyakon (special zone).Using the METEONORM database [42], the following climatic indices are collected for each month of the year and for each settlement selected, namely, the average day and night temperatures as well as the average monthly temperature (Figure 3).These data are used for further analysis of the relevant AHT applications for each climatic zone.The climate in the RF is quite cold, therefore, the most demanded AHT applications are heating, seasonal heat storage, and amplification of the ambient heat [38,43].The heating applications can be realized during winter time only if a free heat source with a temperature of 2-20 • C is available to drive the evaporation process, which can be underground water, waste heat, non-freezing natural water basins, etc.Another opportunity is the use of highly effective solar collectors, which can provide heat at 10-20 • C even under cold climatic conditions.

Analysis of the AHT Cycles Demanded in the RF and Appropriate Working Pairs
Seven settlements from different climatic zones of the RF are chosen for further detailed analysis (Figure 2), namely, Astrakhan (I zone), Moscow (II zone, western part of the RF), Vladivostok (II zone, eastern part of the RF), Omsk (III zone), Arkhangelsk (IV zone, northern part of the RF), Yakutsk (IV zone, eastern part of the RF), and Oymyakon (special zone).Using the METEONORM database [42], the following climatic indices are collected for each month of the year and for each settlement selected, namely, the average day and night temperatures as well as the average monthly temperature (Figure 3).These data are used for further analysis of the relevant AHT applications for each climatic zone.The climate in the RF is quite cold, therefore, the most demanded AHT applications are heating, seasonal heat storage, and amplification of the ambient heat [38,43].The heating applications can be realized during winter time only if a free heat source with a temperature of 2-20 °C is available to drive the evaporation process, which can be underground water, waste heat, non-freezing natural water basins, etc.Another opportunity is the use of highly effective solar collectors, which can provide heat at 10-20 °C even under cold climatic conditions.

Refrigeration/Air Conditioning
Since the average daily temperature in the summer time for the analyzed regions (except Astrakhan) does not exceed 25 °C, the air conditioning application is demanded only for zone I, located in the South of Russia.For all other regions, adsorption refrigeration is considered for

Refrigeration/Air Conditioning
Since the average daily temperature in the summer time for the analyzed regions (except Astrakhan) does not exceed 25 • C, the air conditioning application is demanded only for zone I, located in the South of Russia.For all other regions, adsorption refrigeration is considered for food/drugs storage.The boundary adsorption potentials ∆F 1 and ∆F 2 are calculated (Table 1) according to Equations ( 1) and ( 2).For each location, the condenser/adsorber temperature, Tcon = Tads, is assumed to be equal to the maximum day temperature Td.max of the hottest month of a year (July).The useful effect is produced in the evaporator, and the evaporator temperature Tev equals the temperature Tuh of the required cold, namely, 3 • C for refrigeration and 10 • C for air-conditioning.The operating conditions of the refrigeration cycle are presented in Figure 4 as the colored areas confined between the boundary potentials ∆F 1 and ∆F 2 for the climatic zones analyzed with water as refrigerant.
Table 1.The boundary conditions of cooling cycles analyzed and the amount of water exchanged under the discussed conditions for the adsorbents optimal for each zone.

Refrigeration/Air Conditioning
Since the average daily temperature in the summer time for the analyzed regions (except Astrakhan) does not exceed 25 °C, the air conditioning application is demanded only for zone I, located in the South of Russia.For all other regions, adsorption refrigeration is considered for food/drugs storage.The boundary adsorption potentials ΔF1 and ΔF2 are calculated (Table 1) according to Equations ( 1) and ( 2).For each location, the condenser/adsorber temperature, Tcon = Tads, is assumed to be equal to the maximum day temperature Td.max of the hottest month of a year (July).The useful effect is produced in the evaporator, and the evaporator temperature Tev equals the temperature Tuh of the required cold, namely, 3 °C for refrigeration and 10 °C for air-conditioning.The operating conditions of the refrigeration cycle are presented in Figure 4 as the colored areas confined between the boundary potentials ΔF1 and ΔF2 for the climatic zones analyzed with water as refrigerant.1).The refrigerant is water vapor.
Table 1.The boundary conditions of cooling cycles analyzed and the amount of water exchanged under the discussed conditions for the adsorbents optimal for each zone.

Heating
We consider the adsorptive heating cycle for the domestic production of warm water with the temperature Tuh = 45 • C suitable for dishwashing, cooking, and showering during the warm season (May-September).This is relevant for countryside summer houses, which are very popular in Russia.At heating mode, Tev equals the daily temperature Td.av averaged over each month.The useful heat is produced in a condenser during regeneration and in an adsorber during adsorption stage.The condenser and adsorption temperatures equal the temperature of the useful heat required to the consumer (Tcon = Tads = Tuh).The boundary adsorption potentials ∆F 1 and ∆F 2 are calculated for water as the working fluid by Equations ( 1) and ( 2) for Treg varying from 75 to 90 • C (Table 2).Composites-LiCl/Verm and LiCl/MWCNT, MOFs-MIL-125-NH 2 and CAU-10, and FAM-Z01 appear to be the most promising for the heating mode, with the amount of cycled water ∆w varying from 0.1 to 0.9 g/g for different locations and months (Table 2).For Vladivostok, water heating up to the temperature Tuh = 45 • C is realistic from May to October, but for other zones, only during the summer months (Table 2).The minimum regeneration temperature Treg depends on the conditions during adsorption stage and the ∆F 2 -value.For example, in Oimyakon (zone IV), with low ambient temperature (Tev), an adsorbent with quite strong affinity is required (∆F 2 = 4.2-4.8kJ/mol (Table 2)) to get useful heat at Tuh = 45 • C. A temperature of 75 • C is not enough to drive the cycle, even in summer (Figure 5), because the calculated potential during the adsorption stage is higher than the potential during desorption stage (∆F 2 > ∆F 1 ).This means that regeneration of any studied adsorbent under such conditions is impossible.

Heat Storage
We consider seasonal heat storage when the heat absorbed in summer is used for heating during the cold period.For the RF, providing heating throughout the whole winter using only heat stored in the summer seems not to be realistic due to the cold climate and huge demand for heating.However, the heat storage cycle can be utilized for heating detached or semi-detached houses during a moderately cold autumn and spring, which could lead to the reduction of fossil fuel consumption.At the heat release stage during autumn and spring time, the evaporator is at the ambient temperature, and Tev equals the average night temperature Tn.av.The condenser is at the ambient temperature in summer, when the heat is stored, and Tcon is the average day temperature Td.av during July.The useful heat is produced in an adsorber during the adsorption stage, and the adsorption temperature Tads equals the temperature of useful heat Tuh supplied to a consumer.We consider Tuh = 35 °C, which can be used for floor heating systems.The regeneration temperature is fixed at 90 °C.The adsorption potentials ΔF1 and ΔF2 are calculated using Equations ( 1) and ( 2) with methanol as the working fluid and presented in Table 3.For each location, the optimal adsorbent is proposed based on the amount of methanol cycled (Table 3, Figure 6).

Heat Storage
We consider seasonal heat storage when the heat absorbed in summer is used for heating during the cold period.For the RF, providing heating throughout the whole winter using only heat stored in the summer seems not to be realistic due to the cold climate and huge demand for heating.However, the heat storage cycle can be utilized for heating detached or semi-detached houses during a moderately cold autumn and spring, which could lead to the reduction of fossil fuel consumption.At the heat release stage during autumn and spring time, the evaporator is at the ambient temperature, and Tev equals the average night temperature Tn.av.The condenser is at the ambient temperature in summer, when the heat is stored, and Tcon is the average day temperature Td.av during July.The useful heat is produced in an adsorber during the adsorption stage, and the adsorption temperature Tads equals the temperature of useful heat Tuh supplied to a consumer.We consider Tuh = 35 • C, which can be used for floor heating systems.The regeneration temperature is fixed at 90 • C. The adsorption potentials ∆F 1 and ∆F 2 are calculated using Equations ( 1) and ( 2) with methanol as the working fluid and presented in Table 3.For each location, the optimal adsorbent is proposed based on the amount of methanol cycled (Table 3, Figure 6).If groundwater or domestic waste water at 10 °C can be used as the heat source for evaporation during the cold period, the heat can be produced during winter as well, and the best material for all locations is the LiCl/MWCNT composite.

Heat Amplification Cycle "Heat from Сold" (HeCol)
In the heat amplification cycle "Heat from Cold" (HeCol), recently suggested for upgrading the temperature of the environment heat in cold countries [43], two natural heat reservoirs, namely, the ambient air at low temperature ТL and non-freezing water basins (or underground water) at middle temperature TM, are used as the heat sink and heat source, respectively, to get a useful heat at higher temperature TH suitable for heating (Figure 7) [43].The initial adsorbent state (point 1 in Figure 7) corresponds to the temperature ТM and the pressure of the adsorbate vapor РL = Р0(ТL), where Р0(ТL) is the adsorbate saturation pressure at temperature ТL.Under these conditions, the equilibrium adsorbate content wmin = w(ТM, РL) is low due to the low adsorbate pressure РL.Then, the adsorbent is heated up to temperature TH (stage 1-2) at constant uptake wmin.At point 2, the adsorber is connected to an evaporator maintained at ТM which generates the constant pressure РM = Р0(ТM) of adsorbate.This pressure jump causes the vapor adsorption that leads to an increase in the equilibrium uptake to wmax = w(TH, РM) (point 3 in If groundwater or domestic waste water at 10 • C can be used as the heat source for evaporation during the cold period, the heat can be produced during winter as well, and the best material for all locations is the LiCl/MWCNT composite.

Heat Amplification Cycle "Heat from Cold" (HeCol)
In the heat amplification cycle "Heat from Cold" (HeCol), recently suggested for upgrading the temperature of the environment heat in cold countries [43], two natural heat reservoirs, namely, the ambient air at low temperature T L and non-freezing water basins (or underground water) at middle temperature T M , are used as the heat sink and heat source, respectively, to get a useful heat at higher temperature T H suitable for heating (Figure 7) [43].If groundwater or domestic waste water at 10 °C can be used as the heat source for evaporation during the cold period, the heat can be produced during winter as well, and the best material for all locations is the LiCl/MWCNT composite.

Heat Amplification Cycle "Heat from Сold" (HeCol)
In the heat amplification cycle "Heat from Cold" (HeCol), recently suggested for upgrading the temperature of the environment heat in cold countries [43], two natural heat reservoirs, namely, the ambient air at low temperature ТL and non-freezing water basins (or underground water) at middle temperature TM, are used as the heat sink and heat source, respectively, to get a useful heat at higher temperature TH suitable for heating (Figure 7) [43].The initial adsorbent state (point 1 in Figure 7) corresponds to the temperature ТM and the pressure of the adsorbate vapor РL = Р0(ТL), where Р0(ТL) is the adsorbate saturation pressure at temperature ТL.Under these conditions, the equilibrium adsorbate content wmin = w(ТM, РL) is low due to the low adsorbate pressure РL.Then, the adsorbent is heated up to temperature TH (stage 1-2) at constant uptake wmin.At point 2, the adsorber is connected to an evaporator maintained at ТM which generates the constant pressure РM = Р0(ТM) of adsorbate.This pressure jump causes the vapor adsorption that leads to an increase in the equilibrium uptake to wmax = w(TH, РM) (point 3 in The initial adsorbent state (point 1 in Figure 7) corresponds to the temperature T M and the pressure of the adsorbate vapor P L = P 0 (T L ), where P 0 (T L ) is the adsorbate saturation pressure at temperature T L .Under these conditions, the equilibrium adsorbate content wmin = w(T M , P L ) is low due to the low adsorbate pressure P L .Then, the adsorbent is heated up to temperature T H (stage 1-2) at constant uptake wmin.At point 2, the adsorber is connected to an evaporator maintained at T M which generates the constant pressure P M = P 0 (T M ) of adsorbate.This pressure jump causes the vapor adsorption that leads to an increase in the equilibrium uptake to wmax = w(T H , P M ) (point 3 in Figure 7).For cycles with the useful heat temperature TH = 30 °C, the composite sorbent LiCl/MWCNT appears to be the most promising.LiCl/SiO2 and MaxSorbIII allow the useful heat at TH = 35 °C to be produced.While the LiBr/SiO2 composite with the highest affinity to methanol vapor can be employed for HeCol cycles with the highest useful heat temperature TH = 50 °C (Table 4).

Conclusions
The paper addresses the preliminary feasibility analysis of AHT technology under the climatic conditions of the RF.For each of the seven RF climatic zones selected for the analysis, the most demanded AHT applications, among cooling, heating, heat storage, or amplification, are identified by the analysis of the climatic conditions.For a wide range of conventional and innovative adsorbents (activated carbons, silica gels, MeAPOs, MOFs, composites "salt in porous matrix", etc.), the literature data on their adsorption equilibrium with water and methanol vapors are collected and analyzed.Based on these data, the promising working pairs for the demanded applications for each climatic RF zone are selected.Thus, the analysis carried out demonstrates that AHT technology might have good potential for the RF.The most demanded applications are heating, heat storage, and cooling for food/drug storage.The promising working pairs are selected for each application and each climatic zone.We believe that the obtained results will promote the dissemination of energy and environmentally saving AHT technology in the Russian Federation.For cycles with the useful heat temperature T H = 30 • C, the composite sorbent LiCl/MWCNT appears to be the most promising.LiCl/SiO 2 and MaxSorbIII allow the useful heat at T H = 35 • C to be produced.While the LiBr/SiO 2 composite with the highest affinity to methanol vapor can be employed for HeCol cycles with the highest useful heat temperature T H = 50 • C (Table 4).

Conclusions
The paper addresses the preliminary feasibility analysis of AHT technology under the climatic conditions of the RF.For each of the seven RF climatic zones selected for the analysis, the most demanded AHT applications, among cooling, heating, heat storage, or amplification, are identified by the analysis of the climatic conditions.For a wide range of conventional and innovative adsorbents (activated carbons, silica gels, MeAPOs, MOFs, composites "salt in porous matrix", etc.), the literature data on their adsorption equilibrium with water and methanol vapors are collected and analyzed.Based on these data, the promising working pairs for the demanded applications for each climatic RF zone are selected.Thus, the analysis carried out demonstrates that AHT technology might have good potential for the RF.The most demanded applications are heating, heat storage, and cooling for food/drug storage.The promising working pairs are selected for each application and each climatic zone.We believe that the obtained results will promote the dissemination of energy and environmentally saving AHT technology in the Russian Federation.

Figure 1 .
Figure 1.The P-T diagram of four temperature (4T) absorption heat transformation (AHT) cycle (a), and the universal adsorption curve plotted from experimental isobars of methanol sorption on the composite sorbent LiBr/MWCNT [21] measured at different pressures P 1 = 72.8 (

Figure 2 .
Figure 2. Climatic zones of the Russian Federation (RF) [44] selected for the present analysis.Figure 2. Climatic zones of the Russian Federation (RF) [44] selected for the present analysis.

Figure 2 .
Figure 2. Climatic zones of the Russian Federation (RF) [44] selected for the present analysis.Figure 2. Climatic zones of the Russian Federation (RF) [44] selected for the present analysis.

13 Figure 3 .
Figure 3. Average day (a) and night (b) temperatures for the climatic RF regions selected.

Figure 3 .
Figure 3. Average day (a) and night (b) temperatures for the climatic RF regions selected.

Figure 3 .
Figure 3. Average day (a) and night (b) temperatures for the climatic RF regions selected.

Figure 4 .
Figure 4.The operating ranges of the adsorption potential (colored areas) which correspond to the refrigeration cycle (Tev = 3 °C, Tcon = Tads = Td.max) for the climatic zones analyzed and the universal curves of water adsorption on the adsorbents, optimal for each zone (Table1).The refrigerant is water vapor.

Figure 4 .
Figure 4.The operating ranges of the adsorption potential (colored areas) which correspond to the refrigeration cycle (Tev = 3• C, Tcon = Tads = Td.max) for the climatic zones analyzed and the universal curves of water adsorption on the adsorbents, optimal for each zone (Table1).The refrigerant is water vapor.

Table 2 .
The boundary conditions of the heating cycles, the promising adsorbents, and the amount of exchanged water.

Table 3 .
The boundary adsorption potentials, the promising adsorbents, and the specific mass of methanol exchanged for the tested heat storage cycle (Treg = 90 °C).

Table 3 .
The boundary adsorption potentials, the promising adsorbents, and the specific mass of methanol exchanged for the tested heat storage cycle (Treg = 90 • C).