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Comfort cooling is a growing demand in summer outdoor activities and work. Adsorption cold storage (ACS) can achieve long-term cold storage without insulation measures and release cold without requiring electricity input. However, the challenges, including unstable cooling output and huge volume, hinder its wide applications. In this study, a small-scale silica gel-water ACS prototype for off-grid cooling is developed and experimentally investigated under typical summer conditions. The heat pipe structure is employed in the adsorption bed for heat transfer enhancement and volume reduction. Valve opening control is utilized for cooling output stabilization and adjustment. The experimental results show that the prototype achieves 6.36 h of cooling output with the outlet air temperature of 25 °C and the average cooling power of 107.67 W under the environment conditions of 35 °C and 40 % RH, indicating an effective cold storage capacity of 685 Wh and an operating efficiency of 0.30. Furthermore, the stable output air temperature can be flexibly adjusted from 19 °C to 27 °C while maintaining the inlet air temperature at 35 °C during the discharging process. Notably, the charging environment temperature shows a minimal influence on the cooling output performance. The prototype's design is novel and applicable for portable cooling in outdoor off-grid scenarios. • A portable cooling solution for summer off-grid scenarios based on adsorption cold storage is proposed. • A small-scale silica gel-water adsorption cold storage prototype is developed. • The heat pipe structure is employed for adsorption bed volume reduction. • Stable cooling output is realized through valve opening control. • The prototype achieves a cold storage capacity of 685 Wh and a stable cooling power exceeding 100 W. [ABSTRACT FROM AUTHOR]

Tests of adsorption cooling prototypes with solar energy that use the silica gel–water​ pair have been reported in the literature; however, there is no work that analyzes, compares and integrates them to generate new knowledge from their data and results. In this context, our proposal consists comparing thermodynamic results, determining the characteristics of their parts and functions, and analyzing technical contradictions through the TRIZ methodology, for twelve identified adsorption refrigeration prototypes (including one where a co-author of this paper participated). The results and characteristics of the analyzed prototypes have been systematized, also a diversity of constructive forms was found in the studied prototypes, as well as in the non-standardized results and tests because some aspects were emphasized in each test. The results and simulations are compared using COP and refrigeration capacity as parameters to extrapolate new results consisting of a hybridized conceptual model and projected test results based on those found in the literature.

An adsorption refrigeration system can be driven by low grade heat and uses natural refrigerant with the advantage of reducing the greenhouse gases emission. However, one of the weaknesses is its low efficiency and more importantly its high cost. The recovery of internal waste heat becomes therefore very important in order to improve the coefficient of performance (COP). Analysis based on pinch technology can be helpful to optimal heat recovery operation. In this paper, temperature-heat diagrams and problem tables for adsorption refrigeration systems are proposed and analyzed using Pinch Technology. The results show that pinch point is located between beds and the main waste heat needs to be recovered between beds. Dynamic characteristic (time factor) of adsorption refrigeration system is the main resistance for heat recovery. The effect of pinch point temperature difference on the system COP is not distinct. Furthermore, when the driving temperature is 90°C, the COP of adsorption refrigeration via optimization of pinch analysis is 0.73 which is fairly comparable to LiBr-water absorption refrigeration system. Pinch Technology can be adopted in different types of adsorption refrigeration systems (two-bed, four-bed, mass recovery, et al.). [ABSTRACT FROM AUTHOR]

The half-cycle time effect on the performance of a solar single-stage dual-bed adsorption chiller, in Athens, Greece, in July, is investigated. The adsorption chiller coupled with the solar system is simulated, in real time, during the day for a) constant and b) adjusted half-cycle times and the system performance is monitored. In the former case, the half-cycle time is fixed, while in the latter one is dynamically adjusted according to the varying solar radiation intensity. Using a wide range of constant half-cycle times it is found that the maximum daily cooling capacity is obtained at some constant half-cycle time, which is larger than the optimum one of a single adsorption cycle. Similarly, using a wide range of adjusted half-cycle times, the one, providing the maximum cooling capacity is defined. The analysis is performed in a systematic manner through a proposed algebraic expression. It is found that the dynamically optimized adjusted half-cycle time operation mode provides about 12% higher daily and monthly cooling capacities than the corresponding maximum constant ones. This significant increase has been also confirmed for various incident solar radiation intensities. • The solar thermal system coupled with the adsorption chiller is simulated in real time. • Constant and adjusted half-cycle time scenarios are investigated. • The performance of the solar thermal adsorption chiller is parametrized. • Maximum daily cooling capacity with optimized constant half-cycle time is obtained. • Maximum daily cooling capacity is further increased with adjusted half-cycle time. [ABSTRACT FROM AUTHOR]

In this study, a lumped parameter simulation model has been developed for analysis of the thermal performance of a single-stage two-bed adsorption chiller. Since silica gel has low regeneration temperature and water has high latent heat of vaporisation, silica gel–water pair has been chosen as the working pair of the adsorption chiller. Low-grade waste heat or solar heat at around 70–80°C can be used to run this adsorption chiller. In this model, the effects of operating parameters on the performance of the chiller have been studied. The simulated results show that the cooling capacity of the chiller has an optimum value of 5.95 kW for a cycle time of 1600 s with the hot, cooling, and chilled water inlet temperatures at 85°C, 25°C, and 14°C, respectively. The present model can be utilised to investigate and optimise adsorption chillers.

A small-scale silica gel-water adsorption system with modular adsorber, which utilizes solar energy to achieve the cogeneration of domestic air conditioning and water heating effect, is proposed and investigated in this paper. A heat recovery process between two adsorbers and a mass recovery process between two evaporators are adopted to improve the overall cooling and heating performance. First, the adsorption system is tested under different modes (different mass recovery, heat recovery, and cogeneration time) to determine the optimal operating conditions. Then, the cogeneration performance of domestic cooling and water heating effect is studied at different heat transfer fluid temperatures. The results show that the optimal time for cogeneration, mass recovery, and heat recovery are 600 s, 40 s, and 40 s, respectively. When the inlet temperature of hot water is around 85°C, the largest cooling power and heating power are 8.25 kW and 21.94 kW, respectively. Under the condition of cooling water temperature of 35°C, the obtained maximum COPc, COPh, and SCP of the system are 0.59, 1.39, and 184.5 W/kg, respectively. [ABSTRACT FROM AUTHOR]

• A waste heat driven cooling scheme for data center utilizing adsorption chiller is proposed. • A compact silica gel-water adsorption chiller is developed and experimentally studied under data center waste heat recovery scenario. • The adsorption chiller achieves the cooling power of 4.9 kW and the COP of 0.50 with the hot/cooling/chilled water inlet temperatures of 50 °C/30 °C/23 °C. • The compact adsorption chiller achieves a two-fold increase in volumetric cooling power compared with previous studies. In recent years, data centers have experienced rapid construction, leading to a significant surge in energy consumption, and cooling systems have emerged as prominent energy consumers of data centers. Among the cooling technologies, liquid cooling allows higher cooling circuit temperatures and provides potential for heat recovery. As a thermally driven cooling technology, adsorption refrigeration systems offer an alternative way to compression refrigeration systems by utilizing low-grade waste heat from liquid-cooled circuits to produce chilled water for air-cooled components. In this study, a compact silica gel-water adsorption chiller is developed for a small modular data center and experimentally investigated under extremely low driving temperatures. Under the typical summer conditions with the hot/cooling/chilled water inlet temperatures of 50 °C/30 °C/23 °C, the adsorption chiller achieves the cooling power of 4.9 kW and the COP of 0.50. When the cooling water inlet temperature changes from 32 °C to 24 °C, both the cooling power and COP show significant improvements, from 3.04 kW to 10.50 kW and from 0.44 to 0.66, respectively. Moreover, the increase of the hot water inlet temperature from 48 °C to 56 °C can enhance the cooling power to some extent, while the chilled water inlet temperature has little influence on the performance. The experimental results demonstrate the feasibility and performance of the developed adsorption chiller in data center waste heat driven cooling. Besides, potential adsorbents and possible optimization strategies are presented for performance improvement based on adsorption potential method. [ABSTRACT FROM AUTHOR]

• Propose composite adsorbent with improved heat and mass transfer. • Establish the effect of three types of composite adsorbent on the adsorption refrigeration. • Clarify the impacts of operation parameters on the system with composite adsorbent. Adsorption refrigeration is a typical environmental protection and energy-saving waste heat utilization refrigeration technology. However, improving the heat and mass transfer performance of adsorption beds is crucial to the wide-spread applications of adsorption refrigeration systems. In this paper, three types of composite adsorbents are proposed: adsorbents with improved heat transfer, improved mass transfer, and simultaneously improved heat and mass transfer. Both characteristics of adsorption and heat transfer are tested and compared. Based on the experimental results, the use of these three types of composite adsorbents in the adsorption refrigeration system is further examined. The results indicate that the silica gel (SG)/MIL-100/CF (SGMC) composite outputs the highest cooling capacity and exhibits a coefficient of performance (COP) comparable to that of a composite adsorbent with improved mass transfer. The cooling capacity and COP of the proposed SGMC system compared with those of the traditional SG–water system increase by 22% and 12.8%, respectively, and the refrigeration cycle time is shortened by 16.7%. Based on the optimal SGMC system, the impact of operation parameters is further investigated, and optimum parameters are selected to enhance the overall system performance. [ABSTRACT FROM AUTHOR]

• A 3 kW silica gel-water adsorption air-conditioner is designed and manufactured. • Cooling power and COP can reach 3.98 kW and 0.632, respectively. • Small hot water flow rate can reduce unmatching between heating and cooling operation of adsorption bed. • Adsorption air-conditioner can be used for cooling and heating cogeneration. • Adsorption air-conditioner is suitable for residential solar cooling application. Compared to adsorption chiller, adsorption air-conditioner can get significant benefit of less cost and complexity when it directly provides chilled air for air-conditioning. Hence, adsorption air-conditioner is suitable for residential solar cooling application. A 3 kW adsorption air-conditioner using silica gel-water working pair is designed and manufactured and its performance is fully tested under different conditions. The experimental results show that cooling power and COP can reach 3.98 kW and 0.632, respectively, without obvious periodic fluctuation of chilled air outlet temperature and relative humidity. Smaller hot water flow rate can help to reduce unmatching between heating and cooling operation of adsorption bed. Optimal half cycle time of this adsorption air-conditioner is found to be 750 s. COP of adsorption air-conditioner is generally larger than that of adsorption chiller which provides chilled water because of higher evaporation temperature. Besides, cooling water outlet temperature can reach 39.9 °C which can meet the requirement of domestic hot water use. So that adsorption air-conditioner can be used for cooling and heating cogeneration in a residential solar cooling application and achieve good performance. [ABSTRACT FROM AUTHOR]

Highlights • Developed a prototype for adsorption based cooling for storage. • Cooling performance varied with adsorption/regeneration cycles. • Maximum cooling of 19.8 W was achieved with heating silica gel at 80 °C. • Lowest temperature achieved was 13 °C for storage of fresh mangoes. Abstract Refrigeration is generally recognised as a key tool for successful marketing of fresh produce. However, such sophisticated cooling systems are unavailable or non-existent for African smallholder farmers due to financial constraints and lack of electricity supply. The application of low cost silica gel-water adsorption based cooling systems has attracted attention for on-farm storage. However, the drawback till now was low cooling performance. Therefore, this work focused on evaluating the cooling performance of adsorption based cooling refrigerator (prototype) at different cooling cycle times of 30, 60, 90 and 120 min with regeneration cycles fixed to 30 min and various hot water regeneration temperatures of 60, 70 and 80 °C. The study reveals that the cooling cycle time influences the reduction in storage temperature most, while both increasing hot water temperature and cooling cycle time enhance the cooling capacity of the prototype. Additionally, the adsorption based cooling system prototype was examined on its capability of storing fresh mangoes which resulted in 3% mass loss of fruits at average inside air temperature of 15 °C and relative humidity of 90%. These results suggest that the new energy saving storage technology, can be adopted for storage of fresh commodities in Sub-Saharan African countries. [ABSTRACT FROM AUTHOR]

Highlights • A cascaded mass recovery cycle using multiple mass recovery process is proposed. • Performance of AHP can be significantly improved by cascaded mass recovery cycle. • Cascaded mass recovery cycle is suitable for strict conditions. • Combined system of multi-stage and cascaded mass recovery cycle is efficient. Abstract Using mass recovery process can significantly improve the adsorption heat pump (AHP) system performance. A cascaded mass recovery cycle using multiple mass recovery process is proposed and studied. A theoretical calculation of silica gel–water AHP using different kinds of AHP cycle is performed and the results based on silica gel–water AHPs show that COP/CAQ of cascaded mass recovery cycle is superior to that of basic cycle or conventional mass recovery cycle. In other words, performance of AHP can be significantly improved by cascaded mass recovery cycle. Besides, cascaded mass recovery cycle is suitable for strict conditions of low heat source temperature, high heat sink temperature and low evaporation temperature, and its stage number of mass recovery is suggested to be less than 4 for convenient uses. Combined system of multi-stage and cascaded mass recovery cycle can overcome the disadvantages of high complexity and equipment cost and make the system more efficient and convenient. [ABSTRACT FROM AUTHOR]

In this study, a lumped parameter simulation model has been developed for analysis of the thermal performance of a single-stage two-bed adsorption chiller. Since silica gel has low regeneration temperature and water has high latent heat of vaporisation, silica gel–water pair has been chosen as the working pair of the adsorption chiller. Low-grade waste heat or solar heat at around 70–80°C can be used to run this adsorption chiller. In this model, the effects of operating parameters on the performance of the chiller have been studied. The simulated results show that the cooling capacity of the chiller has an optimum value of 5.95 kW for a cycle time of 1600 s with the hot, cooling, and chilled water inlet temperatures at 85°C, 25°C, and 14°C, respectively. The present model can be utilised to investigate and optimise adsorption chillers. [ABSTRACT FROM AUTHOR]

Combined use of heat and mass recovery processes in adsorption refrigeration is an efficient way to improve the system performance. Several kinds of heat and mass recovery processes have been proposed. In this study, a serial heat recovery process between two adsorbers and a mass recovery-like process between two evaporators is selected. Their operating features in a practical silica gel-water adsorption refrigeration system are experimentally studied. Operating features and performances of heat and mass recovery process can be presented in terms of inlet and outlet temperatures and transferred heat of two adsorbers and two evaporators. The results show that residual heat transfer fluid in the adsorbers and evaporators significantly influences the heat and mass recovery processes, respectively. In the case of this study, optimal ranges of heat and mass recovery time is 25–45 s and 5–50 s, respectively. Heat recovery process can produce negative effect when heat recovery time is beyond 45 s and it is inefficient when heat recovery time is below 25 s. Cooling effect is remarkably yielded when mass recovery time is within the range of 5–50 s. [ABSTRACT FROM AUTHOR]

This paper concerns the issue of the proper selection of the operating parameters of the fluidised desiccant cooler. Despite the fact that fluidised desiccant cooling technology is being reported in the literature as an efficient way to provide cooling for the purposes of air-conditioning, the improper control of its operation can lead to a significantly worse performance than expected. The objective of the presented theoretical study is to provide guidelines on the proper selection of such operating parameters of a fluidized desiccant cooler, such as superficial air velocity, desiccant particle diameter, bed switching time, and desiccant filling height. The influence of the chosen operating parameters on the performance of fluidised desiccant cooling technology is investigated based on their impact on electric and thermal coefficients of performance (COP) and specific cooling power (SCP). Moreover, the influence of the outlet air temperature, humidity, and desiccant water uptake on the adsorption/desorption characteristics was investigated, contributing to better understanding of sorption processes.

This article presents the thermodynamic assessment of an advanced adsorption chiller with an aim towards entropy generation minimization through the selection of appropriate operating strategies, temperatures, and design modifications. The present study carries out a second law analysis of a two-bed silica gel water pair-based adsorption cooling system, with a focus on the under-explored aspects of a heat recovery strategy and auxiliary consumption-reducing measures. A second law performance index, viz. specific irreversibility, is introduced for effectively incorporating the entropy generation, auxiliary electricity consumption, and cooling capacity, and it has been further verified to be an indicator of second law efficiency. The performance of the system has been numerically evaluated under the normal and passive heat recovery strategies, where it is found that the passive heat recovery strategy offers a lower entropy generation by 63%. The study further investigates the second law efficiency impact of adopting a capillary-assisted evaporator for auxiliary electricity consumption reduction. It is observed that the specific irreversibility could reduce by up to 22% over a conventional falling film design. The analysis and results presented in this study are anticipated to increase the effectiveness of adsorption chillers for heat recovery applications. • Entropy generation analysis of a 10 kW adsorption chiller with passive heat recovery • Specific irreversibility is presented for optimum operating point determination • A hot water temperature of 65 °C is optimal for an effective waste heat utilization • Up to 63% reduction is noted on employing passive heat recovery strategy • Specific irreversibility could reduce by 22% with capillary assisted evaporator [ABSTRACT FROM AUTHOR]

A silica gel-water adsorption chiller driven by low-grade heat is developed. System configuration without any vacuum valves includes two sorption chambers, a 4-valve hot/cooling water coupled circuit and a 4-valve chilled water circuit. Each sorption chamber is composed of one adsorber, one condenser and one evaporator. The design of this chiller, especially the design of modular adsorber, is suitable for low-cost industrial production. Efficient and reliable heat and mass recovery processes are also adopted. This chiller is tested under different conditions and it features the periodic variations of temperatures and cooling power. Through the experimental study, the optimal cooling time, mass recovery time and heat recovery time are 720 s, 40 s and 24 s, respectively. Besides, the obtained cooling power, COP and SCP are 42.8 kW, 0.51 and 125.0 W kg −1 , respectively, under typical conditions of 86/30/11 °C hot water inlet/cooling water inlet/chilled water outlet temperatures, respectively. [ABSTRACT FROM AUTHOR]

The performance of adsorption (AD) chillers or desalination cycles is dictated by the rates of heat and mass transfer of adsorbate in adsorbent-packed beds. Conventional granular-adsorbent, packed in fin-tube heat exchangers, suffered from poor heat transfer in heating (desorption) or cooling (adsorption) processes of the batch-operated cycles, with undesirable performance parameters such as higher footprint of plants, low coefficient of performance (COP) of AD cycles and higher capital cost of the machines. The motivation of present work is to mitigate the heat and mass “bottlenecks” of fin-tube heat exchangers by using a powdered-adsorbent cum binder coated onto the fin surfaces of exchangers. Suitable adsorbent–binder pairs have been identified for the silica gel adsorbent with pore surface areas up to 680 m 2 /g and pore diameters less than 6 nm. The parent silica gel remains largely unaffected despite being pulverized into fine particles of 100 μm, and yet maintaining its water uptake characteristics. The paper presents an experimental study on the selection and testing processes to achieve high efficacy of adsorbent–binder coated exchangers. The test results indicate 3.4–4.6 folds improvement in heat transfer rates over the conventional granular-packed method, resulting a faster rate of water uptake by 1.5–2 times on the suitable silica gel type. [ABSTRACT FROM AUTHOR]

This paper presents the thermodynamic frameworks to describe the dynamic uptakes of water vapor on various sizes and layers of silica gels for adsorption cooling applications. The proposed kinetic formulation is developed from the rigor of the partition function of each adsorptive sites and the kinetics theory of adsorbate molecules with the analogy of Langmuir kinetics. The simulation results calculated from the proposed formulation are compared with experimentally measured kinetics data of various single and multi layers configuration of silica gels–water systems. An interesting and useful finding has been established that the proposed model is thermodynamically consistent from the Henry's region to the saturated pressure, and also is connected with the surface structural heterogeneity factors of adsorbents. [ABSTRACT FROM AUTHOR]

This article deals with the experimental investigation of a four-bed adsorption desalination (AD) plant working at a relatively high evaporation temperature. The effect of heat source temperature and adsorption/desorption cycle time on the system performance in terms of specific daily water production (SDWP) and performance ratio (PR) is experimentally studied. Owing to the higher evaporation temperature, SDWP of the plant is increased by two folds, to about 8.2 m³ of water/ton-adsorbent per day. Further improvement is also achieved by using mass recovery scheme without significant changes to the AD plant. [ABSTRACT FROM AUTHOR]

Abstract: The silica gel–water adsorption refrigeration has attracted much attention especially in the last two decades, due to its environmentally friendly refrigeration that can be powered by low grade heat source. In this paper, we reviewed the research about silica gel–water adsorption technology, cooling systems as well as heat pumps. The technological developments of silica gel–water adsorption refrigeration, including working pairs, heat and mass transfer, cycle and system design, simulation work, prototypes and applications, were discussed. The advantages of silica gel–water adsorption refrigeration technology as well as its disadvantages were elucidated. Finally, the prospect of this refrigeration method was analyzed. The weak heat and mass transfer performance of the adsorbent material was the main bottleneck of the silica gel–water adsorption refrigeration technology and resulting in large size, low performance and high cost. [Copyright &y& Elsevier]

Abstract: The potential to use waste heat to co-generate cooling and fresh water from saline water using adsorption on silica is attracting increasing attention. A variety of different thermodynamic cycles of such an adsorption desalination (AD) system arise as the temperature of the saline water evaporator is varied relative to temperature of the water used to cool the adsorbent as it adsorbs the evaporated water. In this paper, all these possible thermodynamic cycles are enumerated and analysed to determine their relative performances in terms of specific energy consumption and fresh water productivity. [Copyright &y& Elsevier]

The potential to use waste heat to co-generate cooling and fresh water from saline water using adsorption on silica recently prompted a detailed study of the performance of adsorption-based desalination (AD) using a thermodynamic model (Wu et al., 2010). Further study has now revealed that the nature of the cycles and the performance are significantly influenced by the evaporator temperature relative to the cooling water temperature. This paper reports this study. Following an enumeration of all possible thermodynamic cycles for an AD system that arise from varying the evaporator temperature relative to the cooling water temperature, the effects of operating water temperatures and the silica gel water vapour capacity on the fresh water productivity and cycle energy consumption are presented and discussed. [ABSTRACT FROM AUTHOR]

Abstract: A lumped parameter model of a silica gel–water adsorption chiller driven by solar energy was introduced for the operating characteristics investigation. Matlab–Simulink, as a high-performance computing and programming tool, was used to simulate the operating characteristics of the chiller. Effects of the hot water tank capacity, the cycle time and the initial hot water temperature on the performance of the chiller were analyzed when the chiller was driven by a stable heat source and solar energy respectively. The simulation results indicated that when the chiller was driven by solar energy, the open circulation of the hot water with a short cycle time and the closed circulation of hot water with a longer cycle time were better. A proposal was also provided for the chiller driven by solar energy to work under the optimum working conditions, such as hot water circulation mode, cycle time and initial temperature. [Copyright &y& Elsevier]

Abstract: A novel silica gel–water adsorption chiller with two chambers has been built in Shanghai Jiao Tong University (SJTU). This chiller combines two single bed systems (basic system) without any vacuum valves. One adsorber, one condenser and one evaporator are housed in the same chamber to constitute one adsorption/desorption unit. In this work, the chiller is developed and improved. The improved chiller is composed of three vacuum chambers: two adsorption/desorption vacuum chambers (the same structure as the former chiller) and one heat pipe working vacuum chamber. The evaporators of these two adsorption/desorption units are combined by a heat pipe. So, no valves are installed in the chilled water sub system and one vacuum valve connects the two adsorption/desorption chambers together to improve its performance. The performance of the chiller is tested. As the results, the refrigerating capacity and the COP of the chiller are, respectively, 8.69kW and 0.388 for the heat source temperature of 82.5°C, the cooling water temperature of 30.4°C and the chilled water outlet temperature of 11.9°C. For a chilled water outlet temperature of 16.5°C, the COP reaches 0.432, while the refrigerating capacity is near 11kW. There is an improvement of at least 12% for the COP compared with the former chillers. [Copyright &y& Elsevier]

Abstract: A silica gel–water adsorption chiller has been developed in recent years and has been applied in an air conditioning system driven by solar energy. The heat source used to drive the adsorption chiller is variable at any moment because the solar radiation intensity or the waste heat from engines varies frequently. An adsorption cooling system may be badly impacted by a variable heat source with temperature variations in a large range. In this work, a silica gel–water adsorption chiller driven by a variable heat source is experimentally studied. The influences of the variable heat source on the performance of the chiller are analyzed, especially for a continuous temperature increase process and a continuous temperature decrease process of the heat source. As an example, the dynamic characteristics of the heat source are also analyzed when solar energy is taken as the heat source of the adsorption chiller. According to the experimental results for the adsorption chiller and the characteristics of the heat source from solar energy, control strategies of the adsorption chiller driven by solar energy are proposed. [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]

Since the energy and environment issues, adsorption refrigeration technology has raised the great attention and interest by worldwide researchers and scholars, because it can efficiently use low-grade heat and its refrigerants are natural. Among the numerous working pairs of adsorption refrigeration, silica gel-water is most suitable for massive applications in solar and waste heat field, as its developed technology and low driving temperature. In this paper, application analysis of adsorption refrigeration system for solar and data center waste heat utilization and economic evaluation, based on investment of main components, operation cost and payback period, is done. For the study of solar cooling application, a validated mathematical model of silica gel-water adsorption chiller is used. For very low temperature waste heat (up to 60 °C) recovery of data center, feasibility of silica gel-water adsorption chiller has been analyzed by previous experimental study. Through the investigation, payback period of solar cooling application using adsorption chiller is too long to get any economic benefit, based on the real weather conditions of Shanghai. Data center waste heat recovery by adsorption chiller has very short payback period and this application has greater economic potential and brighter prospect in the future than solar cooling application. [ABSTRACT FROM AUTHOR]