Design of Adsorptive Heat Storage Devices

2021 ◽  
pp. 89-123
Keyword(s):  
Silica Gel ◽  
Heat Supply ◽  
Sodium Acetate ◽  
Heat Storage ◽  
Sodium Sulphate ◽  
Silica Gels ◽  
Storage Devices ◽  
Composite Adsorbents ◽  
Supply Systems

The chapter is devoted to prospects of application of adsorptive heat storage devices, principles of operating the adsorptive heat storage systems, design of adsorptive storage devices and main factors determining the design of adsorptive heat storage unit. Perspectives of application of adsorptive heat storage devices in heat supply systems were analyzed. Basic principles of operating of heat storage devices were considered. Adsorptive heat storage units operating in close and open modes were compared. Constructions of adsorptive heat storage units operating in open and close mode were described. An efficient algorithm for calculating the volume of the adsorptive thermal energy storage device for a decentralised heat supply system of a private house is suggested by authors. The following procedure of computation is proposed to involve: calculation of thermal load for heating including the determination of thermal losses through external fences, thermal losses due to infiltration and internal heat dissipation, the evaluation of maximal adsorption, adsorption heat, and determination of adsorbent mass and adsorbent volume. The maximal adsorption value is suggested to be calculated by the characteristics of the adsorbent, that is, its maximal adsorption or in the absence of data for a composite adsorbent, as a linear superposition for a mechanical mixture. The adsorbent mass is suggested to calculate as a ratio of a thermal load for heating and heat of adsorption. The adsorbent volume is calculated as ratio of mass and density of adsorbent. An evaluative calculation of the heat load for a private house was carried out with the proposed algorithm. Mass and volumes of conventional silica gels were compared with composite adsorbents ‘silica gel – sodium sulphate' and ‘silica gel – sodium acetate' obtained by sol gel method developed by authors. Mass and volume of silica gels occur to surpass the suggested composite at least by 1.5 – 5 times. This is shown to result from higher maximal adsorption and heat of adsorption of suggested composite adsorbents. The optimal composition of the composite adsorbents ‘silica gel – sodium sulphate' and ‘silica gel – sodium acetate' was determined according to the minimal volume of the layer of heat storage material. Both the lowest volume values and the highest efficiency of a composite adsorbents with a mass ratio of silica gel and Na2SO4 or CH3COONa 20: 80 are explained by the maximum value of adsorption heat. Suggested composite adsorbent ‘silica gel – sodium sulphate' and ‘silica gel – sodium acetate' are shown to be promising for heat supply systems.

Design and Performance of Adsorptive Heat Pumps

2021 ◽  
pp. 223-250
Keyword(s):  
Heat Pump ◽  
Silica Gel ◽  
Heat Supply ◽  
Sodium Acetate ◽  
Energy Performance ◽  
Heat Pumps ◽  
Sodium Sulphate ◽  
Heat Supply Systems ◽  
And Performance ◽  
Supply Systems

The chapter is devoted to design and performance of adsorptive heat pumps. In the first sub-division, state-of-the-art of the adsorptive heat pumping is analyzed. It involves analysing operating principle of adsorptive heat pumps, comparing of the properties of adsorbents used, bed specifications, and operating conditions. Original construction of the adsorptive heat pump is designed by authors for independent heat supply systems or hot water supply of buildings and other structures for various purposes. The composites ‘silica gel – sodium sulphate' or ‘silica gel – sodium acetate' were used as adsorbents. Discharging was performed in a daytime, when heat pump supplied heating system with water warmed to 45 – 35°C. The regeneration mode proceeded at night from 0.00 to 8.00 a.m. Efficiency of suggested adsorptive heat pump is estimated by two methods: as ratio of adsorption heat to sum of desorption heat and external heat supplied to sorbent during its heating up to regeneration temperature (coefficient of performance of cycle) and as ratio of heat of adsorption to heat supplied by solar collector (net coefficient of performance). Suggested heat pump coefficients of energy performance of cycle are stated to be 2.084 when composite ‘silica gel – sodium sulphate' used and 2.021 when ‘silica gel – sodium acetate' used. Seasonal dependence of net coefficient energy performance for suggested adsorptive heat pump based on composites ‘silica gel – sodium sulphate' and ‘silica gel – sodium acetate' is revealed. Correlation of coefficients of energy performance of adsorptive heat pump and composite sorbents properties (sorption capacity and regeneration temperature) is stated. Insignificant decreasing of coefficients of energy performance when ‘silica gel – sodium acetate' used is explained by lower sorptive capacity as compared to ‘silica gel – sodium sulphate'. Suggested heat pump application perspectives are shown for heat supply systems to result from traditional energy sources independence and environmental advantages. Adsorptive heat pumps development challenges, major limitations for commercialization of adsorptive heat pumping, and requirements to ongoing innovations are analysed. The present chapter can be useful for energy efficient decentralized heat supply systems based on adsorptive heat pump unit.

Performance of Adsorptive Heat Storage Devices for Heat Supply

2021 ◽  
pp. 124-173
Keyword(s):  
Silica Gel ◽  
Heat Supply ◽  
Heat Storage ◽  
Sodium Sulphate ◽  
Storage Device ◽  
Efficiency Coefficient ◽  
Composite Adsorbent ◽  
Open Type ◽  
Storage Devices ◽  
Closed Type

The chapter is focused on modelling of performance of adsorptive heat storage devices and estimation of performance of heat storage devices. Two groups of models of adsorptive heat storage units suggested previous researchers are analyzed. The first one is focused on predicting the heat energy storage density, it being based on Dubinin-Polanyi theory. The second one is devoted to analyzing the kinetic of adsorption processes and performance of the adsorber or adsorptive-desorptive reactor filled with traditional adsorbent or salt which forms crystalline hydrates. The key drawback of both groups of models concerns with considering only one stage of exploitation of adsorptive heat storage device in spite of its operating in two-stage mode, that is, alternating discharge (adsorption) and charge (regeneration). It inhibits estimation of efficiency of adsorptive heat storage device basing on full operating cycle and its involving in heat supply system. Two algorithms for estimation of operating parameters are proposed by authors for closed-type and open-type heat storage devices. The algorithm for calculation of operating parameters of closed type adsorptive heat storage device is proposed: calculation of the mass transfer coefficient, adsorption, useful heat, that is, heat of adsorption, determination of the heat input, it being calculated as heat inputs for heating the adsorbent, device housing, water in the tank, evaporation of water in the tank, heating of the adsorbed water and desorption. Then efficiency factor is calculated. The operating characteristics of a closed-type heat energy storage device were studied when the composite adsorbent ‘silica gel – sodium sulphate' used. The effect of the humid airflow velocity on the efficiency factor is taken into account by introducing a coefficient equal to the value of the adsorption. An increase in the efficiency coefficient was stated when the velocity and relative humidity of the airflow. It is shown that the humid air flow temperature practically does not affect its value. Having been used the suggested algorithm, the optimal operating characteristics of an adsorptive heat storage device of a closed type based on a composite adsorbent ‘silica gel – sodium sulphate' for a private house heating system are revealed to be humid air velocities of 0.6 – 0.8 m/s and relative humidity 40 – 60%. When these operational data applied, the efficiency coefficient is shown to reach the maximum values (about 55%). Algorithm of calculation of operating parameter of open-type heat storage device includes computation of mass transfer coefficient, adsorption, useful heat (heat of adsorption), heat input for heating the adsorbent, device casing, water in the humidifier, evaporation of water, heating the adsorbed water, desorption, and calculating efficiency coefficient. Performance of open-type heat storage device based on the composite adsorbent ‘silica gel – sodium sulphate' is estimated. The optimal operating conditions of the heat accumulating device which allow operating with maximal magnitudes of efficiency coefficients 53 – 57% are stated to be humid airflow speed of 0.6 – 0.8 m/s and relative humidity of 40 – 60%. Correlation between efficiency factors obtained by experiments and calculated with suggested algorithm is confirmed. The possibility of reducing the power consumption when heat storage devices applied in 2,4 – 90 times versus decentralized heating systems on basis of solid fuel boiler, gas boiler and electric boiler is stated when open-type sorptive heat storage device used. Results of the study can be used to develop adsorptive storage devices in decentralized heat supply and ventilation systems and adsorption units for utilization of low-temperature waste heat.

scholarly journals PERFORMANCE EVALUATION OF ADSORPTIVE REFRIGERATORS BASED ON COMPOSITE ADSORBENTS "SILICA GEL – SODIUM SULPHATE" AND "SILICA GEL – SODIUM ACETATE"

2019 ◽  
Vol 2 (83) ◽  
Author(s):  
Олена Анатоліївна Бєляновська ◽  
Григорій Миколайович Pustovoy ◽  
Михайло Порфирович Сухий ◽  
Костянтин Михайлович Сухий ◽  
Роман Дмитрович Литовченко
Keyword(s):  
Surface Area ◽  
Silica Gel ◽  
Solar Collector ◽  
Sodium Acetate ◽  
Sodium Sulphate ◽  
Coefficient Of Performance ◽  
Operational Parameters ◽  
Composite Adsorbents ◽  
Operational Characteristics ◽  
Cold Box

Abstract. Performance of adsorptive refrigerators based on composite adsorbents  ‘silica gel – sodium sulphate’ and ‘silica gel – sodium acetate’ was evaluated. The main characteristics of adsorbents which affect the structural parameters of the adsorptive chilling device are revealed. The method of determining operational characteristics of adsorptive refrigerator has been developed. The main factors affecting the mass of adsorbent are confirmed to be maximal adsorption and the amount of heat required to be taken from the cold box during the day. The advantages of ‘salt in the porous silica gel matrix’ composites are exhibited as compared with conventional silica gels and zeolites. Operational parameters of adsorptive refrigerators based on the composites ‘silica gel – sodium sulphate’ and 'silica gel – sodium acetate' are compared. The calculation procedure to determine the design and operational characteristics is suggested. Proposed procedure includes the calculation of the amount of heat required to be taken from the cold box during the day, water mass, mass of the adsorbent, heat required for regeneration of the adsorbent, computing the surface area of the solar collector, heat supplied by solar collector and net coefficient of performance. The efficiency of operating processes of adsorptive refrigerators based on composites 'silica gel - sodium sulphate' and 'silica gel-sodium acetate' was compared. The correlation between adsorbent composition and design and operational parameters was stated. The surface area of solar collector is stated to be of 9.46 – 9.93. The highest net coefficients of performance of 0.358 and 0.368 are revealed for devices based on composites containing, wt. %: silica gel – 20 and salt (sodium sulphate or sodium acetate) – 80. The influence of meteorological conditions on the net coefficient of performance of the adsorptive refrigerator has been confirmed. The higher efficiency of adsorptive chilling devices based on composites 'silica gel - sodium acetate' is explained by lower values of regeneration temperature, which leads to the decreasing the heat of regeneration. The results of the research can be used for the development of adsorptive chilling devices for domestic needs and warehouse premises.

Technology of Heat and Moisture Regeneration for Ventilation Systems

2021 ◽  
pp. 174-222
Keyword(s):  
Silica Gel ◽  
Air Temperature ◽  
Sodium Acetate ◽  
Temperature Drop ◽  
Sodium Sulphate ◽  
Efficiency Factor ◽  
Cold Air ◽  
Temperature Efficiency ◽  
Heat And Moisture ◽  
Ventilation Systems

The chapter is focused on technology of heat and moisture regeneration for ventilation systems. In the first sub-division recent progress in adsorptive technologies for air dehumidification, heating and conditioning is analyzed. In the next sub-divisions results of original researches of authors on adsorptive heat and moisture regeneration are given. The design of adsorptive heat-moisture regenerator for ventilation systems is shown. Its operation and the results of field tests are described. The technology of regeneration of low-potential heat and moisture by composite sorbent ‘silica gel – sodium sulphate' is suggested. Experimental plots of temperature, absolute and relative humidity at the inlet and the outlet of the apparatus and between cassettes with the composite are given. Correlation of flows switch-over time, airflow rate and temperature drop is stated. The relationships temperature efficiency factor vs. dimensionless temperature drop and moisture efficiency factor vs. absolute humidity dimensionless drop are derived with fair accuracy for engineering calculation. Ability of purposeful modification of the above-mentioned characteristics within broad ranges by changing the half-cycle time, the size of the granules of the adsorbent and its amount is revealed. The mathematical model and algorithm for determining the basic parameters of adsorptive regenerator operating processes are developed. The proposed algorithm involves calculating the volume of air passed through the layer of adsorptive heat-storage material, the concentration of water in the airflow at the outlet of the regenerator, the adsorption, the heat of adsorption, the final temperature of the cold air, the air temperature after mixing the cold air from the street and the warm air in the room at the warm end of the regenerator during inflow, calculation of the final concentration of water in the flow at the cold end of the regenerator, the volume of air passing through the layer of heat-accumulating material, adsorption and heat of adsorption, the final temperature of the air at the cold end of the regenerator, the air temperature after mixing of the cold air from the street and the warm air from the room at the cold end of regenerator during outflow, determining the temperature efficiency coefficient, summarized adsorption and maximal adsorption time. The correlation of air temperatures near the warm and cold end of the regenerator, as well as the temperature efficiency factors calculated according to the proposed algorithm and obtained by experimental way is confirmed. The mathematical modeling of the processes of operation of adsorption regenerators based on composites ‘silica gel – sodium sulphate' and ‘sodium acetate' in the conditions of the typical ventilation system of residential premises is carried out. The dependences of the temperature efficiency factor vs. the time of switching air flows and the velocity of air flow, as well as the temperatures of external and internal air under stationary conditions are shown. An optimal composition of composite adsorbents is stated to be 20% of silica gel and 80% of salt, that is, sodium sulphate or sodium acetate. Due to higher value of maximal adsorption composite ‘silica gel – Na2SO4' is shown to be required in half as much as compared with ‘silica gel – CH3COONa'. The results of the research can be used in the development of energy-efficient ventilation systems and devices for residential and warehouse premises.

Structure and Properties of Composite Adsorbents Salt Inside Porous Matrix

2021 ◽  
pp. 43-87
Keyword(s):  
Silica Gel ◽  
Sol Gel ◽  
Salt Content ◽  
Porous Matrix ◽  
Sodium Sulphate ◽  
Crystalline Hydrate ◽  
Host Matrix ◽  
Gel Method ◽  
Composite Adsorbents ◽  
Silicon Oxygen

The chapter is devoted to structure and properties of composite adsorbents ‘salt inside porous matrix'. Characteristics of adsorbents ‘salt inside porous matrix', such as ‘zeolite – crystalline hydrate', ‘vermiculite – crystalline hydrate', ‘silica gel – crystalline hydrate' were analysed. Main advantages of composite adsorbents are shown to be higher adsorptive capacity and lower regeneration temperature as compared with host matrix. Adsorptive capacities of composite materials are shown to be significantly enhanced by introduction of salts in host matrix such as zeolite, vermiculite, or silica gel. Water uptake by composite adsorbent is shown to be increased by rising the salt content in it. The drawback of most of existing impregnation technologies is shown to be impossibility of obtaining composite with salt content more than 40 – 60% along with complexity. Sol gel method is shown to be an alternative for conventional impregnation methods. Properties of adsorbents ‘silica gel – sodium sulphate' synthesized according to sol gel method developed by authors were considered. The composite ‘silica gel – sodium sulphate' composition and structure were studied by IR-spectroscopy and wide-angle x-ray scattering. Adsorptive properties of crystalline Na2SO4 when allocated in silicon oxygen matrix are shown to result from dispersion up to nanoscale. Adsorptive capacities and heat of adsorption of composites ‘silica gel – sodium sulphate' and ‘silica gel – sodium acetate' surpass almost by 30% the value calculated from the linear superposition of the sorption capacities of the sorbent and massive salt. Their adsorption properties are shown to be not a linear combination of properties of silica gel and salt. The formation of a unique structure promoting an increase in the rate of reaction between crystalline hydrates and water vapor in the developed pores of the silicon-oxygen matrix is confirmed. It leads to increasing the heat of adsorption and the heat energy storage density. Strong difference of water sorption kinetic curves of composite ‘silica gel – sodium sulphate' and massive sodium sulphate is revealed. The correlation of their composition, structure, water adsorption kinetic, and operating characteristic as heat storage material is stated.

scholarly journals Determination of additional factors in assessing the reliability of heat supply systems

2019 ◽  
Vol 288 ◽  
pp. 012076 ◽  
Author(s):  
I G Akhmetova ◽  
A A Kalyutik ◽  
A V Fedukhin ◽  
O V Derevianko ◽  
L R Mukhametova
Keyword(s):  
Heat Supply ◽  
Heat Supply Systems ◽  
Supply Systems

scholarly journals Energy efficient operational processes of adsorptive heat storage device based on composite “silica gel – sodium sulphate”

2019 ◽  
Vol 3(477) ◽  
pp. 27-34
Author(s):  
Olena A. Bielianovska ◽  
Roman D. Lytovchenko ◽  
Kostiantyn M. Sukhyi ◽  
Anton E. Buzov ◽  
Mykhailo P. Sukhyi
Keyword(s):  
Silica Gel ◽  
Energy Efficient ◽  
Heat Storage ◽  
Sodium Sulphate ◽  
Storage Device ◽  
Operational Processes

scholarly journals IDENTIFICATION OF SOME CARCINOGENIC POLYCYCLIC AROMATIC HYDROCARBONS IN BANGLADESHI VEHICLES EXHAUST TAR BY GAS CHROMATOGRAPHY-MASS SPECTROPHOTOMETER

2010 ◽  
Vol 8 (3) ◽  
pp. 353-355 ◽  
Author(s):  
M. Amzad Hossain ◽  
S. M. Salehuddin
Keyword(s):  
Gas Chromatography ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Glass Fiber ◽  
Silica Gel ◽  
Aromatic Hydrocarbons ◽  
Solvent Mixture ◽  
Sodium Sulphate ◽  
Glass Fiber Filter ◽  
Polycyclic Aromatic

A more sensitive GC-MS method has been established for the determination of some carcinogenic polycyclic aromatic hydrocarbons (PAHs) in vehicles exhaust tar samples. The tar samples were extracted using dichloromethane (DMC): n-hexane solvent mixture. A multi-layer clean-up (silica gel/sodium sulphate) column was used, followed by glass fiber filter (GFF) paper. The method was successfully applied to determine a number of PAHs present in exhaust tar sample of different vehicles of the Atomic Energy Centre, Dhaka, Bangladesh.   Keywords: Carcinogenic polycyclic aromatic hydrocarbons, vehicles tar samples, identification, GC-MS/MS

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