A study on thermal energy storage using open adsorption system (original) (raw)
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Experimental investigation of an adsorptive thermal energy storage
International Journal of Energy Research, 2007
A zeolite-water adsorption module, which has been originally constructed for an adsorption heat pump, has been experimentally investigated as an adsorptive thermal energy storage unit. The adsorber/desorber heat exchanger contains 13.2 kg of zeolite 13X and is connected to an evaporator/condenser heat exchanger via a butterfly valve. The flow rate of the heat transfer fluid in the adsorber/desorber unit has been changed between 0.5 and 2.0 l min À1 , the inlet temperature to the evaporator between 10 and 408C. It turned out that the higher the flow rate inside the adsorber/desorber unit the faster and more effective is the discharge of heat. However, at lower flow rates higher discharge temperatures are obtained. Storage capacities of 2.7 and 3.1 kWh have been measured at the evaporator inlet temperatures of 10 and 408C, respectively, corresponding to thermal energy storage densities of 80 and 92 kWh m À3 based on the volume of the adsorber unit. The measured maximum power density increases from 144 to 165 kWh m À3 as the flow rate in the adsorber increases from 0.5 to 2 l min À1. An internal insulation in form of a radiation shield around the adsorber heat exchanger is recommended to reduce the thermal losses of the adsorptive storage.
Fundamental study on solar powered adsorption cooling system
Journal of Chemical Engineering of Japan, 1984
Fundamental experiments on the solar-powered adsorption cooling system were carried out with small-scale apparatus simulating ideally a practical unit by employing a combination of silica-gel and water vapor as an example of the adsorbent-adsorbate combinations. A simple model which takes into account both adsorption properties and apparatus characteristics was proposed to interpret our experimental results quantitatively. Then the transitional behavior of heat and mass transfer in continuous adsorption-regeneration experiments was successfully interpreted by the model. The model proposed here is not a complete one and is to be considered as a first-step model for estimating operation with practical equipment. Also, the contribution of the level of regeneration temperature of adsorbents to the cooling performance was quantitatively clarified on the basis of the adsorption equilibrium relation, which is considered useful in choosing a favorable combination of adsorbent and adsorbate for the system.
Experimental study of an adsorption heat storage systems for building applications
Renewable Bioresources, 2016
In this paper, an Adsorption Heat Storage System (AdHS-R134a)/heating system utilising Vermiculite and Calcium Chloride composite adsorbent material was experimentally investigated. The main aim of the experimental investigations is to carry out preliminary tests on a small scale Adsorption Heat Storage Systems (AdHS-R134a) using a heat pump circuit as the regeneration heat source. The test rig was constructed using Vertical Glass Pipes with a heat pump circuit using a mini compressor for transporting the refrigeration gas as a heat source for desorption cycle. The system also incorporates condenser coils, evaporator coils, and an expansion valve. The integration with a heat pump circuit is to analyse the performance of an AdHS-R134a using off-peak power in desorption/charging cycle or utilising renewable energy sources to minimise conventional energy generated from fossil fuels. Firstly, desorption phase occurs during night hours, when cheap off-peak electricity is available under the 'Economy 7' tariff that is more suitable for households with night storage heaters or if we use lots of electricity at night. Secondly, in the heat pumping phase/adsorption loop which will occur during the day. The useful heat of adsorption in the adsorbent pipe could be used for underfloor heating (35°C-40°C), or for domestic hot water production (55°C-60°C) during the day. The maximum temperature lift observed from the adsorption process is 68.67°C (inside adsorption pipe) with the corresponding COP of 0.55-1.39.
A review on adsorption cooling systems with silica gel and carbon as adsorbents
Renewable and Sustainable Energy Reviews, 2015
This study presents adsorption cooling systems with silica gel and activated carbon as adsorbents. Adsorption cooling systems powered by low grade heat sources are presented here. Moreover, the previous experimental and numerical models are discussed. The study revealed that the performances of silica gel and activated carbon based adsorption cooling systems are still low and hence these systems are in the stage of demonstration and prototyping. It was concluded that there is still an opportunity for adopting more modern solar energy collecting and transferring technologies, and more advanced design optimization and simulation models. However, heat recovery, mass recovery, multi-bed and multi-stage technologies are promising technologies in improving the COP and SCP of these systems.
Experimental chiller with silica gel: Adsorption kinetics analysis and performance evaluation
Energy Conversion and Management, 2017
Adsorption technology is a promising, low carbon intensity option for air conditioning and refrigeration. Adsorption kinetics is a key performance factor for such systems. This paper presents an adsorption kinetics and performance assessment of an experimental adsorption chiller with silica gel and water as working pair. The adsorbent bed heat exchanger is equipped with silica gel in loose grains fitted between finned tubes. Pressure, temperature and adsorbate flow measurements along the thermodynamic cycle are performed for two different options of adsorbent particle fraction sizes to compare the resulting dynamics and performance. COP is 0.53 and SCP is 68 WÁkg À1 for 2.0 mm dia. silica gel and a 80/30/15°C triplet. COP is 4 % worse when 0.26 mm silica gel is used, due to the lower porosity and lower thermal conductivity presented by the crushed adsorbent. A mass diffusion algorithm is considered in the numerical model. Good agreement between experimental and calculated data has been reached. The maximum temperature level needed for desorption in the 70-80°C range is compatible with the use of water heated by flat-type solar collectors, and low-grade waste heat from industrial processes.
Adsorption Heat Storage: State-of-the-Art and Future Perspectives
Nanomaterials (Basel, Switzerland), 2018
Thermal energy storage (TES) is a key technology to enhance the efficiency of energy systems as well as to increase the share of renewable energies. In this context, the present paper reports a literature review of the recent advancement in the field of adsorption TES systems. After an initial introduction concerning different heat storage technologies, the working principle of the adsorption TES is explained and compared to other technologies. Subsequently, promising features and critical issues at a material, component and system level are deeply analyzed and the ongoing activities to make this technology ready for marketing are introduced.
2016
The performance of two adsorbent bed silica gel-water adsorption chiller and the influences of its adsorbent bed dimensions, the velocity of heat exchange fluid and the adsorbent particle diameter on the transient distributions of the solid phase temperature, adsorbate concentration and the pressure are numerically examined in this study. A transient two-dimensional local thermal non-equilibrium model that takes into account both internal and external mass transfer resistances is developed to simulate the adsorption chiller considered herein. The internal and external mass transfers are predicted by the linear driving force (LDF) model and Darcy’s equation, respectively. It is found that an increase in the adsorbent particle diameter results in the decrease in both the coefficient of performance (COP) and specific cooling power (SCP) of the adsorption chiller. On the other hand, the system performance is nearly independent from the variation of velocity of heat exchange fluid. An in...
Experimental Analysis of a Solar Adsorption System Refrigeration Cycle with Silica-Gel/Water Pair
HAL (Le Centre pour la Communication Scientifique Directe), 2021
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Performance Evaluation of Silica gel /water Adsorption Cooling Unit
ERJ. Engineering Research Journal
In the present work, an experimental study of adsorption refrigeration unit with modified adsorption bed is obtained. Silica gel and water are used as a working pair in the adsorption refrigeration unit. Hot air is used for Silica gel regeneration. The effect of evaporator pressure, evaporator inlet water temperature, initial Silica gel temperature, and hot air regeneration temperature and mass flow rate on the unit coefficient of performance is studied. It has been found that increase of hot air regeneration temperature and inlet evaporator temperature increases the unit refrigeration capacity and coefficient of performance. On the other hand, a decrease of Silica gel temperature and evaporator pressure increases the unit refrigeration capacity and coefficient of performance. The results confirm that this kind of adsorption chiller is an effective refrigerating machine, it can be used for air conditioning or producing chilling water since it make a reduction in the chilling water temperature more than 10ºC in 3 minutes. In addition the present unit with its novel adsorber gives higher coefficient of performance than that was obtained from the similar previous models
DEVELOPMENT OF A SOLAR POWERED ADSORPTION CHILLER
Heat driven cooling technologies like vapour absorption and adsorption systems are environmentally friendly. Use of thermal compression in these systems saves precious and fast-depleting fossil fuel resources. Solar energy and low-grade waste heat can be effectively used in running these cooling systems. The present work focuses on the development of a solar-powered vapour adsorption based cooling system, which have the potential to be a carbon-free alternative to vapour compression cooling cycles, especially for meeting domestic and office space requirements. Poor heat and mass transfer properties of the adsorbents lead to bigger sizes and more cost. Use of thin beds along with integrally finned tubes has been adopted in this work to augment the heat transfer through the bed. A temperature distribution profile of the silica gel bed has been developed through finite difference method, to have an in-depth study of the heat transfer process during desorption. A test unit of adsorption chiller has been developed for round the year parametric study with a heat pipe based evacuated tube solar water heater installed on the roof.