Solar Adsorption Refrigeration System Research Articles

Experimental and theoretical analysis of the solar adsorption refrigeration system under south Iraq climate condition

This study investigates the performance of a solar adsorption refrigeration system utilizing activated carbon and methanol as the adsorbent/adsorbate combination in the context of the climate conditions in southern Iraq. The primary aim is to develop an efficient and environmentally friendly refrigeration technology that can operate off-grid, particularly in regions with limited access to electricity. Through a combination of experimental trials and theoretical analysis, the research explores the impact of factors such as solar radiation intensity, collector design, and operational parameters on system efficiency. The findings reveal that the tubular form of the collector/adsorber enhances system performance by simplifying maintenance and reducing the risk of leaks. Additionally, the study demonstrates the system's capability to cool water significantly, showcasing its potential for practical applications. The key contribution of this research lies in its innovative approach to solar refrigeration technology, offering a sustainable solution for cooling needs in challenging environments. The solar-driven refrigerator achieves a COP of 0.38 (ambient 30 °C) using 5.5 kg of carbon and 0.24 kg of methanol. Collector efficiency reaches 43 % under peak sun (847 W/m2), with a theoretical maximum of 51 % (1000 W/m2). The refrigerator cools 1 L of water from 30 °C to −0.6 °C, demonstrating its potential for sustainable refrigeration and reduced reliance on fossil fuels. These findings contribute to advancing solar-driven refrigeration and reducing reliance on fossil fuels. To counteract climate change, this work lays out a practical road towards sustainable refrigeration.

Solar adsorption refrigeration system: Comparison between equilibrium, universal and transient model

Three models of different level of complexity are detailed in order to predict the cold production of a solar cooling device. The transient model consists on a heat and mass transfer model of the absorber, coupled with a solar collector model which conceives the ambient temperature as variable along the day and comprehends the evolution of the solar radiation throughout the day according the locations of the prototype to be analyzed in addition to the ideal models of the condenser and evaporator. The Equilibrium and Universal Model are both lumped models in which the spacial distributions of the variables and the heat and mass transfer resistance in the system are disregarded. The advantages and disadvantages of each model are discussed.The results of the models are compared with experimental data obtained from four methanol/activated-carbon adsorption refrigerator prototypes. The cold generated is underestimated 12%–20% by the transient model, while it is overestimated 22%–46% by the equilibrium model and 53%–66% by the universal model. Even when the transient model allows some improvements, is a useful tool to analyze the impact that different variables of a solar adsorption refrigeration system have in the generation of cold. The simpler models can be used for preliminary design and feasibility studies of solar adsorption refrigeration devices (SARS) whose results can be extrapolated on the premise of its overestimation of cold generation approximately given by this work.

Performance Assessment of Silica Gel-Water Solar Adsorption Refrigeration System in Egypt

Performance Assessment of Silica Gel-Water Solar Adsorption Refrigeration System in Egypt

Dynamic variation of bed parameters and time optimisation of solar adsorption refrigeration system based on CFD simulation

One major reason for the limited application of adsorption refrigeration systems is their lower refrigeration efficiency and performance compared to other alternatives. Additionally, there is limited research focused on optimizing the system performance over time. This paper presents a numerically validated thermodynamic model to analyse the effect of adsorption time on the performance efficiency enhancement of a solar adsorption refrigeration system. The adsorption rate model proposed by Sokoda and Suzuki has been used to evaluate the adsorption and desorption characteristics of water vapor on silica gel and the solar collector system has been fitted to a heat flow density equation based on measured concentrated solar heating. The water vapor adsorption capacity on silica gel as a function of temperature and pressure in the adsorption bed has been numerically evaluated during the four stages of the cooling cycle, namely adsorption, preheating, desorption, and cooling. The coefficient of performance and specific cooling power have been utilized as the major performance indicators, in the context of the influence of adsorption time on the refrigeration performance of the system. The simulation results revealed that, although increasing the adsorption time increased the system's cooling capacity, it also prolonged the cycle time and adversely affected the dynamics of preheating and desorption processes (due to increased solar input). As a result of the numerical simulation, an optimum value of adsorption time has been predicted to be 71 min corresponding to a coefficient of performance equal to 0.476 and a specific cooling power equal to 28.6 W/kg.

Heat storage in solar adsorption refrigeration systems: A case study for indigenous fruits preservation

The present study deals with heat storage in a solar-powered refrigeration system designed for indigenous products preservation in a cold room with a positive temperature. One of the key goals of this study is to show the importance of heat storage and the choice of the suitable coupling, position, and technology of thermal heat storage in these systems to ensure energy management and system operation flexibility. A new system configuration design where the direct connection between the solar collectors and the adsorption chiller used in the directly driven chiller without any heat storage module and in the classic storing system is suppressed and a new special regulation system is added to manage the temperature of the supplied water to the adsorption chiller. Under the same solar collectors' area, the new configuration design performs well than the existing configurations and offers more flexibility and stability to the system. It was found that, the heat storage, performed by a Hot Water Tank (HWT), enhances the system's cooling production time duration as well as offers stability and reduces the highly fluctuant hot water temperature in solar adsorption chillers. It's shown that the choice of the adsorption chiller cycle time duration is of great importance as well as the HWT volume on the system's performance. The study shows also that the system achieves better performances when considering a stratified HWT instead of a fully mixed HWT. Using a total solar collectors' area of 84.53 m2, a hot water tank of 3 m3, and a cycle time of 1200 s, a solar fraction of 86% is obtained when the proposed configuration is connected to the stratified heat storage technology however 80% is reached when the system is equipped with the mixed hot water tank.

Transient simulation and design parameters optimization of a cold store utilizes solar assisted adsorption refrigeration system

Storing of products at their recommended storage temperature plays a vital role in products cost estimation especially in hot and humid climate. In this paper, a simulation of a solar assisted adsorption refrigeration system utilized in cold stores applications is carried out for hot-humid and hot-dry climatic conditions. Then an optimization based on the system design parameters have been performed to get the optimal system performance and maximum solar fraction. Finally, the optimized system performance characteristics have been evaluated monthly at different product storage temperatures for different climatic conditions. Reported results revealed that, an optimum solar collector area of 40 m2, storage tank volume of 1.5 m3 and collector flow rate 1000 kg/h are required to achieve an annual solar fraction of 0.79. Based on the annual system performance, SF and COP increase as cold store temperature increase for both climatic conditions. In fact, hot-dry climate has higher SF and COP at 13 °C than hot-humid by 6% and 11%, respectively. Furthermore, the economic assessment of the proposed system showed that the minimum LCOC of 0.203 USD/kWh is found at hot-dry climate at cold store temperature of 18 °C while the highest LCOC of 0.485 USD/kWh occurred at hot-humid environment at 13 °C.

Parametric study of reflectivity transmittance of materials for potential solar adsorption refrigeration system

Abstract One of the most promising alternative energy sources has been recognized as solar energy. Solar energy may be utilized for electricity, solar thermal and power generation directly or indirectly. Sun adsorbing refrigeration systems require adsorbing qualities, which can be produced by concentrated solar energy collectors. Previous research has found that the collector components’ reflectivity transmittance is one of the characteristics that have a substantial impact on the performance of a solar adsorption refrigeration system. For the first time, the solar insolation of Reflectech mirror, a new solar concentration material was compared parametrically with three popular solar concentration materials (metallic film, aluminium film and polymer film) that have been used for solar adsorption application. The optimized simulation results revealed that employing Reflectech film in the design of the solar adsorption refrigerating system has the ability to reflect the maximum solar insolation of 144.5 W/m2 in comparison with metallic film with 119.75 W/m2, aluminium film with 100 W/m2 and polymer film with 68.67 W/m2. Thereby, implying that the Reflectech film has the potential of producing the highest system coefficient of performance than the other materials is under research for all periods under study.

Experimental studies on solar assisted activated carbon based adsorption refrigeration system

The refrigeration and air conditioning has become an integral part of today’s life in both domestic and industrial sector and is continuously growing beyond one’s imagination resulted in the price rise of fossil fuels and negative environmental impact due to the existing cooling technologies which works mainly on vapour compression principles using traditional refrigerants. This results in the emission of harmful gases which in turn causes global warming and ozone layer depletion. This has made to find the refrigeration system which is reliable, pollution free, environmental friendly and economical. In this context heat operated systems such as adsorption refrigerators run by low heat source temperatures from solar or waste heat energy are gaining significant importance for cold production. The cooling systems run by vapour adsorption principles are favourable in terms of eco-friendliness and reliability but the coefficient of performance (COP) that can be achieved is low and hence are not able to compete with the vapour compression systems which is due to the lack of technological development. Hence the research activities are still ongoing in this area to solve the environmental, technical and economic issues. The literature indicates that the adsorption refrigeration system’s performance depends upon the working pair used such as silica gel-water, activated carbon-ammonia, zeolite-water etc. and driving temperature. It is also observed that in India, research related to adsorption refrigeration is rare. Hence in the present work using activated carbon and methanol as the working pair, experimental studies are carried out on a solar assisted double bed adsorption refrigeration system to evaluate the performance under different working conditions. Results show that the lowest cool down temperature noticed in the evaporator under no load condition is 2 °C for the operated cycle time and the values of COP obtained were in the range of 0.1–0.3 for different operating parameters studied. The adsorption system is viable to produce cold even with low temperature source of heat.

TRNSYS 16: A veritable solar modelling and programming simulation tool used in the design of a continuous solar powered adsorption refrigeration system

Project feasibility gave rise to the need for simulation. Simulation of a project leads to reduction in production cost, which ensures the success of the proposed project. Also, it provides initial design data for the experimental project. Thus, the design analysis and variables used for project simulation must be designed properly, revised, tested, and re-tested to guarantee how accurate the experimental design is. Hence, solar adsorption refrigeration system was designed, simulated and constructed using zeolite 4A/13X blend and water. The models were simulated using TRNSYS 16.0 simulation tool. From the result, it was observed that the collector area increases with increase in the system COP from month to month. The highest system COP of 1.53 was obtained in the month of April while the least was 0.4 for July due to frequent rainfall. Also, a much high COP was obtained for dry season while lower COP was gotten for harmattan season. Key words: TRNSYS, adsorption refrigeration, solar cooling, solar adsorption, adsorbent, solar concentrating collectors.

Potential applications of solar refrigeration systems for permafrost cooling in embankment engineering

This paper presents the results of an evaluation of two solar-assisted refrigeration systems in protecting permafrost foundations in railway and roadway engineering. A technical comparison was conducted between two types of traditional permafrost cooling measures and refrigeration systems: vapor compression and heat-driven adsorption. The investigated refrigeration systems have better real-time performance and effectiveness than traditional passive heat regulation measures. Moreover, the permafrost regions in China have good potential for solar energy, addressing the issue of decentralized power supply for refrigeration. Two special permafrost cooling systems were designed, manufactured, and tested; the solar photovoltaic vapor compression refrigeration system (SPV-VCRS) and the solar photothermal adsorption refrigeration system (SPT-ARS). The SPV-VCRS prototype exhibits greater potential for permafrost protection, with a consecutive average temperature of −23.55 °C and a coefficient of performance (COP) of 0.41 in the warm season. The SPT-ARS prototype is characterized by an intermittent refrigeration temperature of −1.83 °C and a significantly lower COP of 0.054 per day. Based on the results, suggestions have been given for the selection of solar refrigeration systems for application in the protection of the permafrost under embankments.

Modeling and Simulation Study of a Solar Adsorption Refrigeration System to Highlight Its Performance under the Desert Climate Conditions

Modeling and Simulation Study of a Solar Adsorption Refrigeration System to Highlight Its Performance under the Desert Climate Conditions

Thermodynamic analysis and performance evaluation of activated carbon-ethanol two-bed solar adsorption cooling system

• Thermodynamic analysis of a two bed solar adsorption refrigeration system is presented. • Activated carbon-ethanol is the best adsorbent-adsorbate pair for the continuous operating adsorption cooling cycle. • The maximum C O P S Y of the system is 0.68 for the desorption temperature of 95 °C. • Dependency of performance parameters with desorption temperature is studied. • Isothermal adsorption is thermodynamically efficient as compared to isobaric adsorption. In this study, a thermodynamic model for analysing the performance of a two-bed solar adsorption cooling system (SAC) has been presented. It projects isothermal adsorption instead of isobaric to reduce the heat of adsorption and hence improve the performance of SAC system. An adsorption chiller of 500 W capacity operating at an evaporator temperature of 5 °C and a condenser temperature of 45 °C is selected for the present research. The proposed adsorption chiller uses activated carbon/ethanol as the working pair. The refrigeration cycle operates between an evaporator pressure of 2.01 kPa and a condenser pressure of 23.1 kPa. The input heat distribution in the bed component, followed by, assessing the effect of maximum desorption temperature on the performance of the system is also carried out. The maximum coefficient of performance of 0.68 is observed for a desorption temperature of 95 °C.The thermal performance of the system is also studied for adsorbate fraction, adsorbent bed pressure and effect of desorption temperature on various parameters. It has been found that the isothermal adsorption process increases the thermal performance of the SAC and it is estimated that coefficient of performance of the system with isothermal adsorption is 13.23% times more when compared with conventional isobaric adsorption. The study aims at providing a formidable solution to the low performance of adsorption cooling systems.

Numerical investigation of the solar activated carbon/methanol adsorption refrigeration system in Tehran’s climate

Solar adsorption refrigeration systems are used to extract heat using solar radiation based on the adsorption phenomena. In these systems, the temperature of the solar collector plays an important role in the efficiency of a system. In this study, two different models, including the lumped and the distributed ones, are investigated to predict the temperature distribution in a specific solar collector. The operating conditions are the same for both cases. Moreover, for the solar radiation as one of the boundary conditions, the data for Tehran solar irradiation is used. The results of the temperature analysis show that the distributed model predicts a less maximum collector temperature than the lumped model which clearly results in a lower system performance. In addition, it can be concluded that because of using steel as a main material for the collector and its high thermal capacitance, it takes almost 3 days for the system to reach the periodic operating conditions.

Recent progress and outlook of solar adsorption refrigeration systems

Solar adsorption refrigeration systems are indispensable in the areas of cooling such as air conditioning, ice making, food preservation, medicine and vaccine storage etc in remote areas. It is cheaper than other devices and lack in noise and corrosion. It is completely an eco-friendly system which could be driven by low grade waste heat. Consumption of electricity is very less in this system as compared to other fields due to the elimination of compression process in adsorption refrigeration. Most of the adsorption system delivers a COP between 0.1 and 0.2 and exceptions are also there. Because of the technical, economic and environmental problems, researches are going on in these areas. Nowadays it is incorporated with vapour compression system to make hybrid system in order to achieve a greater COP and efficiency. This paper presents the basic and advanced aspects of adsorption refrigeration cycle and its hybrid arrangements with pre-existing system. This paper described the different types of conventional and novel adsorbent – adsorbate working pairs and provides detailed review about the past and present state of art research in this field.

Pemanfaatan Energi Surya untuk Sistem Refrigerasi Berbasis Siklus Adsorpsi

Application of solar adsorption refrigeration systems has developed significantly since 1980’s. Although it has some advantages like noiseless, non-corrosive and environment friendly operation (because solar energy is one of green and renewable energy), but until now the application still cannot compete with the traditional vapor compression refrigeration systems. Fortunately, due to the increasing of awareness about ozone depletion and global warming, green technology including solar adsorption refrigeration systems still becomes priority research is developed by some country. Recent research in application of solar adsorption refrigeration systems not only focus in how to increase the coefficient of performance (COP) like the use of various collectors or working pairs but also how to implement the systems so that suitable with the location that it will be applied. Nowadays, application of solar adsorption refrigeration systems mostly varies into 3 categories: ice maker, cool chamber and humanitarian aid. And the application’s usage usually implement in remote area that far from grid electricity.

Impact of three different enhancing mass transfer operating characteristics on a solar adsorption refrigeration system with compound parabolic concentrator

An adsorption refrigeration system using a compound parabolic concentrator adsorber and an enhanced mass transfer method can improve the system performance. However, different operating modes and different methods of mass transfer enhancement within the system affect the performance heavily. The work compares system performances with four operating modes: three different enhanced mass transfer modes and the natural mass transfer mode. Comparative experiments are conducted under an indoor solar simulator scenario. The different performance parameters were compared, and the results showed that the system performance in all the enhanced mass transfer modes, i.e., mode 1 (one pump with one condenser), mode 2 (one pump with two condensers) and mode 3 (two pumps with two condensers), was higher than that of natural mass transfer mode (no pump with one condenser). The quantity of desorbed refrigerant increased by at least 11.8%, 19.0% and 17.1%, and the coefficient of performance increased by at least 10.0%, 18.4% and 15.8% or enhanced mass transfer modes 1, 2 and 3, respectively, compared with those of the natural mass transfer mode. The results also showed that mode 2 yielded the optimal performance, with the lowest system pressure and highest refrigerant desorption among the three enhanced mass transfer modes.

Experimental study of a solar adsorption refrigeration system integrated with a compound parabolic concentrator based on an enhanced mass transfer cycle in Kunming, China

A new solar adsorption refrigeration system integrated with a compound parabolic concentrator (CPC) adsorber was proposed. Comparative experiments were conducted to investigate the system behaviour with the enhanced and natural mass transfer cycle under different weather conditions in Kunming, China. The parameter λ (the refrigerant utilization ratio) was defined to describe and compare the effective utilization ratio of the refrigerant in a refrigeration cycle for some different adsorption refrigeration system with a different quantity of the adsorbent and refrigerant. The results show that the system performance level with the enhanced mass transfer cycle is always higher than the system performance level with the natural mass transfer cycle under different weather conditions. On sunny day with a clear sky, the volume of the desorbed refrigerant and the COPsolar with the enhanced mass transfer cycle were increased by 39.2% and 39.0%, respectively, compared with the natural mass transfer cycle. The refrigerant utilization ratio in the CPC adsorption refrigeration system could be improved by 32.5% and 51.2% for the natural and enhanced mass transfer cycle compared with the non-CPC adsorption refrigeration system, respectively. While on sunny day with a partly cloudy sky, the volume of the desorbed refrigerants and the COPsolar with the enhanced mass transfer cycle were improved by 51.7% and 52.8%, respectively, compared with the natural mass transfer cycle. And the refrigerant utilization ratio in the CPC adsorption refrigeration system improved by 33.5% and 61.2%, respectively, for the natural and enhanced mass transfer cycle compared with the non-CPC adsorption refrigeration system.

Examination of heat transfer performance of a nonimaging hybrid compound parabolic collector in low latitude and cloudy region

AbstractThis work investigates the characteristics of nonimaging hybrid compound parabolic collector (HCPC) for enhancement of heat transfer to the reactor of solar adsorption refrigeration system (SARS) in low latitude and cloudy region. A HCPC is simulated and developed to heat cylindrical reactor of SARS. The HCPC is used to heat the reactor with solar energy during high insolation while auxiliary heating system is used during low insolation. Simulation results show that the reactor adsorbent (activated carbon) is heated to average temperatures between 70 and 85°C when the solar radiance is between 350 and 450 W/m2. However, the experimental results are observed to be slightly deviated from the simulated results due to environmental factors, such as wind speed, cloud, and dust, which cannot be correctly predicted. It is inferred that HCPC is effective in heating SARS cylindrical reactor to start adsorption refrigeration process in low latitude and cloudy region.

Heat transfer performance investigation on a finned tube adsorbent bed with a compound parabolic concentrator (CPC) for solar adsorption refrigeration

In this work, activated carbon-methanol was used as the working pair in a solar adsorption refrigeration system (SAR). The thermal conductivity of the activated carbon was very poor, resulting in performance delays of the system. To improve the performance of the heat transfer for the adsorbent bed, a new adsorbent bed with finned tubes was designed and studied using commercial computational fluid dynamics (CFD) software. Two-dimensional (2D) numerical models of two kinds of adsorbent tubes (finned and smooth tubes) were constructed and simulated. The two different 2D numerical models had similar cell numbers and the same boundaries and initial conditions. An experiment for a grid verification model of the designed finned tube was conducted, and the model of the finned tube was validated via comparison between the numerical and experimental results. In addition, the heat performances of the newly designed finned tube and the smooth tube were compared in this paper. The temperature gradients of the activated carbon in the smooth and finned tubes were approximately 28.1 °C and 4 °C during isosteric heating, respectively. The conclusions are that the fins had a large effect on the thermal performance of SAR, and the possibility that the methanol was adsorbed again by the activated carbon of the lower temperature part in the finned tubes during isobaric heating was decreased greatly. Moreover, the radial heat loss of the finned tube wall was also less than the smooth tube, which may be an important factor for improving the performance of the system effectively.

Analysis of Adsorption Time for Solar Adsorption Refrigeration System

Analysis of Adsorption Time for Solar Adsorption Refrigeration System