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Accurate estimation of the isosteric heat of adsorption is mandatory for a good modeling of adsorption processes. In this paper a thermodynamic formalism on adsorbed phase volume which is a function of adsorption pressure and temperature has been proposed for the precise estimation of the isosteric heat of adsorption. The estimated isosteric heat of adsorption using the new correlation has been compared with measured values of prudently selected several adsorbent-refrigerant pairs from open literature. Results showed that the proposed isosteric heat of adsorption correlation fits the experimentally measured values better than the Clausius-Clapeyron equation. [ABSTRACT FROM AUTHOR]

In the present study, water vapor adsorption onto silica-gel, activated carbon powder (ACP) and activated carbon fiber (ACF) has been experimentally measured at 20 °C, 30 °C and 50 °C. The adsorption data is fitted with Guggenheim–Anderson–De Boer and Dubinin–Astakhov adsorption models for silica-gel and ACP/ACF, respectively. Steady-state moisture cycled (MC SS ) is determined for greenhouse demand category-I, II and III which are based on 60%, 40% and 20% relative humidity of dehumidified air, respectively. The ACP and ACF enable maximum MC SS for demand category-I and II, respectively. However, the silica-gel is found the only applicable adsorbent for demand category-III. [ABSTRACT FROM AUTHOR]

The study investigates the effect of mass recovery process on the performance of a conventional two bed solar adsorption cooling system with direct solar coupling mathematically. In an adsorption refrigeration system, the pressure in adsorber and desorber are different. The mass recovery scheme utilizes this pressure difference to enhance the refrigerant mass circulation. Average Cooling Capacity (ACC) and Coefficient of Performance (COP) were calculated by computer simulation to analyze the influences of operating conditions. The results show that the average cooling capacity of mass recovery system is superior to that of conventional system. It is also seen that mass recovery process enhances the overall performances of solar driven chiller and there is an optimum mass recovery time for an adsorption cooling system with direct solar coupling [ABSTRACT FROM AUTHOR]

This paper presented a theoretical framework for precise determination of the isosteric heat of adsorption for non-ideal gases. The derived equation had been applied for various adsorbent–refrigerant pairs. Highly porous activated carbon powder, namely Maxsorb III and activated carbon fiber of type (A-20) were used as adsorbents with HFC-134a and HFC-410a as refrigerants. The isosteric heat of adsorption data showed lower values comparing to the isosteric heat of adsorption without the consideration of non-ideality of gases. An empirical formula to perceive the isosteric heat of adsorption of HFCs gases on to activated carbons had been extracted. Effect of the proposed isosteric heat of adsorption on the performance of adsorption cooling system based on activated carbon powder/HFC-134a had also been discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: An adsorption cooling system has been designed and built employing granular activated carbon (GAC)–R134a as adsorbent–refrigerant pair. The performance of the system has been determined using a cycle simulation computer program written in Fortran. The performance of the system has been determined varying driving heat source inlet temperatures and delivered evaporator temperatures. The maximum driving heat source temperature is kept below 100 °C to utilize solar thermal energy or waste heat sources. The results showed good agreement between the theoretical and experimental data. The maximum theoretical coefficient of performance (COP) is obtained as 0.35. The experimental specific cooling energy (SCE) is reached up to 70 kJ kg−1 whereas the maximum theoretical SCE of the system is 83 kJ kg−1. The pressurized-bed adsorption cooling system can effectively utilize low grade waste heat of temperature below 100 °C. [Copyright &y& Elsevier]

Abstract: With sharp rising global energy demand posing a rapid development in sustainable cooling systems is required. Hybrid adsorption cooling cycle is considered as one of the sustainable cooling systems. The present study introduces a survey of hybrid adsorption cooling systems in order to stand on its fact and clarify the future trend. The survey sectioned the hybrid adsorption systems into three sections; (i) assisted technology, (ii) application, and (iii) heat source type. The hybrid system which uses vapor compression with adsorption employing activated carbon/CO2 pair was found to have the highest value of the coefficient of performance (COP). On the contrary, vapor compression-hybrid cooling system using activated carbon/R134a as the adsorbent/refrigerant pair has the lowest COP value and substantial research development and demonstration (RD&D) is required to meet the global challenge of energy conservation. [Copyright &y& Elsevier]

Abstract: The objective of this article is to evaluate adsorption kinetics of R134a and R507A on pitch based activated carbon experimentally by a constant volume variable pressure method at different adsorption temperatures ranging from 20 to 60 °C. These data are useful for the design of adsorption cooling and refrigeration systems and are unavailable in the literature. Data obtained from the kinetic studies were analyzed with various kinetic models and the Fickian diffusion model is found to be the most suitable overall. Guided by the experimental measurements, the surface diffusion is also estimated and is found that it follows the classical Arrhenius law within the experimental range. [Copyright &y& Elsevier]

Abstract: This paper presents adsorption isotherms of R-134a (HFC-134a) on highly porous pitch based activated carbon (Maxsorb III) in the temperature range of 5–70°C and pressures up to 12bar, using desorption method. The experimental data have been fitted with the Dubinin–Astakhov (D–A) isotherm equation. The adsorption isotherms of R-134a on Maxsorb III obtained from the present study are compared with the adsorption isotherm results of R-134a on similar type of adsorbents obtained by other researchers and they are found to be fairly consistent. The isosteric heat of adsorption of the assorted adsorbent–refrigerant pair has also been extracted from the present experimental data. [Copyright &y& Elsevier]

Abstract: The purpose of this paper is to provide empirical correlations for isosteric heats of adsorption on carbon based adsorbents for two refrigerants namely ethanol and HFC 134a. A non-dimensional correlation which partitions the contributions of the concentration and temperature dependence is proposed. The correlation is tested out against data obtained from experimental isotherms of ethanol adsorption on activated carbon fibers [ACF (A-20) and ACF (A-15)] and HFC 134a on two specimens of activated carbon powders and one specimen of carbon granules. It is expected that the suggested correlation will be useful for designers of adsorption chillers where indenting heat inventories fulcrums on the magnitude of isosteric heat of adsorption. [Copyright &y& Elsevier]

Abstract: In this paper, a detailed parametric study on a dual-mode silica gel–water adsorption chiller is performed. This advanced adsorption chiller utilizes effectively low-temperature solar or waste heat sources of temperature between 40 and 95°C. Two operation modes are possible for the advanced chiller. The first operation mode will be to work as a highly efficient conventional chiller where the driving source temperature is between 60 and 95°C. The second operation mode will be to work as an advanced three-stage adsorption chiller where the available driving source temperature is very low (between 40 and 60°C). With this very low driving source temperature in combination with a coolant at 30°C, no other cycle except an advanced adsorption cycle with staged regeneration will be operational. In this paper, the effect of chilled-water inlet temperature, heat transfer fluid flow rates and adsorption–desorption cycle time effect on cooling capacity and COP of the dual-mode chiller is performed. Simulation results show that both cooling capacity and COP values increase with the increase of chilled water inlet temperature with driving source temperature at 50 and 80°C in three-stage mode, and single-stage multi-bed mode, respectively. However, the delivered chilled-water temperature increases with chilled-water inlet temperature in both modes. [Copyright &y& Elsevier]

Significant efforts have been done in order to improve adsorption desalination systems by developing advanced adsorbents. Silica-supported ionic liquid (SIL) has been recently proposed as a promising adsorption material for water desalination due to its relatively high adsorption capacity around 1 kg water.kg SIL −1. Such achieved performance can be considered as an initial cornerstone that requires further important additional data before reaching a successful practical application. In this paper, experimental measurements of water adsorption kinetics in the SIL named EMIM-AC/Syloid 72FP are presented. The kinetics is interpreted using a linear driving force (LDF) model that shows good harmony with experimental data. Depending on a former study on adsorption isotherms and the current kinetics data, the performance of an adsorption water desalination system (ADS) is predicted using a dynamic lumped parameter model. The results show a bright future for this SIL material in water desalination application with high theoretical pure water production achieving 47 m3 day−1ton−1, 0.85 coefficient of performance with 600 W kg SIL −1 specific cooling power. Furthermore, system working with the EMIM-AC/Syloid 72FP can theoretically be powered by as low as 40 °C heat source. • Adsorption kinetics of silica supported ionic liquid/water are measured. • Adsorption desalination system using SIL is modeled. • A specific daily water production of 47 m3 day−1ton−1 is reached. • The system could be driven by low temperature heat (40 °C). [ABSTRACT FROM AUTHOR]

This study introduces a new adsorbent/refrigerant pair to be used in adsorption cooling applications. Adsorption isotherms and kinetics of Difluoroethane (HFC-152a) onto highly porous activated carbon Maxsorb III at temperatures ranging from 25 to 75°C have been investigated. Experimental data of adsorption uptake have been fitted with Dubinin–Astakhov (D–A) and Tóth equations. D–A equation is found to be more suitable than Tóth equation for fitting the adsorption uptake. Experimental results showed that Maxsorb III can adsorb up to 1.3 kg of HFC-152a per kg of adsorbent. Experimental data of adsorption kinetics have been fitted with linear driving force (LDF) and Fickian diffusion (FD) models. Both LDF and FD models are found to be able to simulate the adsorption kinetics of the proposed pair. Isosteric heat of adsorption has been estimated considering the real gas case. Pressure–temperature–concentration (P–T–C) diagram of the pair has been also presented. [ABSTRACT FROM AUTHOR]

Abstract: This study is a survey for working adsorbent–refrigerant pairs and the new pairs for potential applications. The study introduces a classification for the adsorption cooling systems and a comparison between them based on the employed adsorption pairs. The comparison is on the basis of the limits of use such as coefficient of performance (COP), driving temperature, evaporation temperature and specific cooling power (SCP). The study also introduces a review of the most promising new adsorption pairs. The new pairs are introduced from the point of view of its adsorption characteristics. Finally, the study concluded that the future of adsorption cooling could be more popular as it will offer answers for the existing challenges. [Copyright &y& Elsevier]